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diff --git a/.gitattributes b/.gitattributes new file mode 100644 index 0000000..6833f05 --- /dev/null +++ b/.gitattributes @@ -0,0 +1,3 @@ +* text=auto +*.txt text +*.md text diff --git a/33429-8.txt b/33429-8.txt new file mode 100644 index 0000000..20f3efb --- /dev/null +++ b/33429-8.txt @@ -0,0 +1,12372 @@ +Project Gutenberg's The Philosophy of the Weather, by Thomas Belden Butler + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: The Philosophy of the Weather + And a Guide to Its Changes + +Author: Thomas Belden Butler + +Release Date: August 14, 2010 [EBook #33429] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK THE PHILOSOPHY OF THE WEATHER *** + + + + +Produced by Robin Monks and the Online Distributed +Proofreading Team at http://www.pgdp.net (This book was +produced from scanned images of public domain material +from the Google Print project and from The Internet Archive: +American Libraries.) + + + + + + + + + + THE PHILOSOPHY OF THE WEATHER. + AND A GUIDE TO ITS CHANGES. + + + BY T. B. BUTLER. + + + NEW YORK: + D. APPLETON & COMPANY, + NOS. 346 & 348 BROADWAY. + 1856. + + + + + Entered according to Act of Congress, in the year 1856, by + T. B. BUTLER, + In the Clerks Office of the District Court of the District of + Connecticut. + + + ELECTROTYPED BY + THOMAS B. SMITH, + 82 & 84 Beekman Street. + + + PRINTED BY + J. F. TROW, + 379 Broadway. + + + + +INTRODUCTION. + + +The atmospheric conditions and phenomena which constitute "The Weather" +are of surpassing interest. Now, we rejoice in the genial air and warm +rains of spring, which clothe the earth with verdure; in the alternating +heat and showers of summer, which insure the bountiful harvest; in the +milder, ripening sunshine of autumn; or the mantle of snow and the +invigorating air of a moderate winter's-day. Now, again, we suffer from +drenching rains and, devastating floods, or excessive and debilitating +heat and parching drought, or sudden and unseasonable frost, or extreme +cold. And now, death and destruction come upon us or our property, at any +season, in the gale, the hurricane, or the tornado; or a succession of +sudden or peculiar changes blight our expected crops, and plant in our +systems the seeds of epidemic disease and death. These, and other normal +conditions, and varied changes, and violent extremes, potent for good or +evil, are continually alternating above and around us. They affect our +health and personal comfort, and, through those with whom we are +connected, our social and domestic enjoyments. They influence our business +prosperity directly, or indirectly, through our near or remote dependence +upon others. They limit our pleasures and amusements--they control the +realities of to-day, and the anticipations of to-morrow. None can +prudently disregard them; few can withhold from them a constant attention. +Scientific men, and others, devote to them daily hours of careful +observation and registration. Devout Christians regard them as the +special agencies of an over-ruling Providence. The prudent, fear their +sudden, or silent and mysterious changes; the timid, their awful +manifestations of power; and they are, to each and all of us, ever present +objects of unfailing interest. + +This _interest_ finds constant expression in our intercourse with each +other. A recent English writer has said: "The germ of meteorology is, as +it were, innate in the mind of every Englishman--the weather is his first +thought after every salutation." In the qualified sense in which this was +probably intended, it is, doubtless, equally true of us. Indeed, it is +often not only a "first thought" _after_ a salutation, but a part of the +salutation itself--an offspring of the same friendly feeling, or a part of +the same habit, which dictates the salutation--an expression of sympathy +in a subject of common and absorbing interest--a sorrowing or rejoicing +with those who sorrow or rejoice in the frowns and smiles of an +ever-changing, ever-influential atmosphere. + +If consistent with our purpose, it would be exceedingly interesting to +trace the varied forms of expression in use among different classes and +callings, and see how indicative they are of character and employment. + +The sailor deals mainly with the winds of the hour, and to him all the +other phases of the weather are comparatively indifferent. He speaks of +airs, and breezes, and squalls, and gales, and hurricanes; or of such +appearances of the sky as prognosticate them. The citizens, whose lives +are a succession of _days_, deal in such adjectives as characterize the +weather of _the day_, according to their class, or temperament, or +business; and it is pleasant, or fine, or _very_ pleasant or fine; +beautiful, delightful, splendid, or glorious; or unpleasant, rainy, +stormy, dismal, dreadful or horrible. The farmer deals with the weather +of considerable periods; with forward or backward _seasons_, with "cold +snaps" or "hot spells," and "wet spells" or "dry spells." And there are +many intermediate varieties. The acute observer will find much in them to +instruct and amuse him, and will probably be surprised to find how much +they have to do with his "first impressions" of others. + +But I have a more important object in view. I propose to deal with "The +PHILOSOPHY _of the Weather_"--to examine the nature and operation of the +arrangements from which the phenomena result; to strip the subject, if +possible, of some of the complication and mystery in which traditionary +axioms and false theories continue to envelop it; to endeavor to grasp +_its principles_, and unfold them in a plain, concise, and systematic +manner, to the comprehension of "_the many_," who are equal partners with +the scientific in its practical, if not in its philosophic interest; and +to deduce a few general rules by which its changes may be understood, and, +ultimately, to a considerable extent, foreseen. + +This is not an easy, perhaps not a prudent undertaking. Nor is my position +exactly that of a volunteer. A few words seem necessary, therefore, by way +of apology and explanation. + +In the fall of 1853, in the evening of a fair autumnal day, I started for +Hartford, in the express train. Just above Meriden, an acquaintance +sitting beside me, who had been felicitating himself on the prospect of +fine weather for a journey to the north, called my attention to several +small patches of scud--clouds he called them--to the eastward of us, +between us and the full clear moon, which seemed to be enlarging and +traveling south--and asked what they meant. + +"Ah!" said I, "they are scud, forming over the central and northern +portions of Connecticut, induced and attracted by the influence of a +storm which is passing from the westward to the eastward, over the +northern parts of New England, and are traveling toward it in a southerly +surface wind, which we have run into. They seem to go south, because we +are running north faster than they. You see them at the eastward because +they are forming successively as the storm and its influence passes in +that direction, and are most readily seen in the range of the moon; but +when we reach Hartford you will see them in every direction, more numerous +and dense, running north to underlie that storm." + +I had seen such appearances too many times to be deceived. It was so. When +we arrived at Hartford they were visible in all directions, running to the +northward at the rate of twenty-five miles an hour. In the space of forty +minutes we had passed from a clear, calm atmosphere (and which still +remained so), into a cloudy, damp air, and brisk wind blowing in the same +direction we were traveling, and toward a heavy storm. My friend passed +on, and met the southern edge of the rain at Deerfield, and had a most +unpleasant journey during the forenoon of the next day. Taking the cars +soon afterwards, in the afternoon, for the south, I found him on his +return. + +"Shall I have fair weather now till I get home?" said he. + +"There are no indications of a storm here, or at present," I replied, "but +we may observe them elsewhere, and at nightfall." + +He kept a sharp look-out, and, as we neared New Haven, discovered faint +lines of cirrus cloud low down in the west, extending in parallel bars, +contracting into threads, up from the western horizon, in an E. N. E. +direction toward the zenith. + +"Now, what is that?" said he. + +"The eastern outlying edge of a N. E. storm, approaching from the W. S. W. +It is now raining from 150 to 200 miles to the westward of the eastern +extremity of those bars of cirrus-condensation; perhaps more, perhaps +less; and under those bars of condensation the wind is attracted, and is +blowing from the N. E. toward the body of the storm, and where the +condensation is sufficiently dense to drop rain. That dense portion will +reach here, and it will rain from twelve to fifteen hours hence. As we +pass along the shore, and run under that out-lying advance +cirrus-condensation, we shall see that the vessels in the Sound have the +wind from the N. E., freshening, but we shall continue to have this light +and scarcely-perceptible air from the northward for a time--_the N. E. +wind always setting in toward an approaching storm, out on the Sound, much +sooner than upon the land_." + +As we approached the storm, and the storm us, the evidence of denser +condensation at the west, and of wind from the east, blowing toward it, +became more apparent. The fore and aft vessels were running "up Sound" +with "sheet out and boom off," before a fresh N. E. breeze, and my friend +was astonished. + +"I must understand this," said he; "how is it?" + +"All very simple. The page of nature spread out above us is intelligible +to him who will attentively study it. The laws which produce the +impressions and changes upon that page, are few and comprehensible. +Although there is great variety, even upon the limited portion which is +bounded by our horizon, there is also substantial uniformity; and, +although the changes are always extensive, often covering an area of one +thousand miles or more, and our vision can not extend in any direction +more than from thirty to fifty, yet those changes are always, to a +considerable extent, intelligible, and may often be foreseen." + +"Has meteorology made such progress?" + +"By no means. It has, indeed, been raised to the dignity of a science, and +professorships endowed for its advancement. Some books have been written, +and many theories broached in relation to it; and innumerable observations +of the states of the barometer and thermometer, of the clouds, and the +quantity of fallen rain, and the direction and force of the wind--made and +recorded simultaneously in different countries--have been published and +compared; and a great many important facts established, and tables of +'_means_' constructed, and just inferences drawn, yet the _few and simple +arrangements_ upon which all the phenomena depend, and _their philosophy_, +have not yet been clearly elicited or understood." + +"Have not the 'American Association for the Advancement of Science' +arrived at some definite and sound conclusion upon the subject?" + +"No; it has been with them, for many years, an interesting subject for +papers and debate. Some very valuable articles, upon particular topics, or +branches of the subject, have been read and published. But the +_Cyclonologists_, as they term themselves, and who seem to think the great +question is, '_Are storms whirlwinds?_' appear with new editions and +phases of their favorite views as regularly as the annual meeting recurs; +and, though they have not convinced, they seem to have silenced their +opponents. The only conclusion, however, judging from their debates, to +which the Association appear to have come with any considerable unanimity, +is, that they are yet without sufficient _authentic observations_ and +well-established facts, to authorize the adoption of the Huttonian, +Daltonian, Gyratory, or Aspiratory, or any of the other numerous theories +which abound. And they are right. The subject is mystified by these +theories and speculations of the study, founded on barometrical and +thermometrical records, and the direction and force of the surface winds. + +"The qualities of heat were among the earlier discoveries of science, and +all the phenomena of the weather were forthwith attributed to its +influence. Hastily-formed and erroneous views of its power, and the manner +of its action in particular localities, and under particular +circumstances, have retained the credence accorded to them when first +announced, although subsequent discoveries have shown their fallacy; some +new theory of _modification_ having been invented to reconcile the +discrepancies as soon as they appeared. Perhaps it is not too much to say +(however it may seem to one not thoroughly acquainted with the subject, +who does not know that the _primary_ and secondary modifying hypotheses +found in Kämtz, may be counted by hundreds) that there is not remaining in +any other science, and possibly in all others, an equal amount of false +and absurd theory, and of forced and unnatural grouping of admitted facts +to sustain it, as in meteorology as at present taught and received. +Astronomy, as a science, is almost perfected--the nature, and size, and +orbits, of the distant worlds around us are known--while constant changes +and alternating atmospheric conditions, which all occur _within less than +six miles of us_, affecting all our important interests, and obvious to +our senses, although much talked off, and made the objects of many +theories, are but little understood." + +"How, then, did you acquire the information you seem to possess?" + +"By studying '_the countenance of the sky_,' for in no other way has such +information ever been, or can it ever be, acquired. By a long-continued, +daily, and sometimes hourly observation of the clouds and currents of the +atmosphere, in connection with such reports of the then state of the +weather elsewhere, as have fallen under my notice, and the effect of its +changes upon the animal creation--for very much can be learned from them. +Yonder flock of black ducks that sit on that inshore rock, above the +tide--the wildest and most suspicious of all their tribe--although the +air is calm about them, know well that a storm is at hand. They probably +both see and feel it. As twilight approaches they will fly away inland, +forty or fifty miles perhaps, and settle among the lilies or grass which +surround some fresh-water pond, certain of remaining while the storm +lasts, and for one day at least, out of danger, and undisturbed. Many a +time, in my boyhood, have I heard, in the stillness of evening, the +whistling of their wings, as they swept up the Connecticut valley, to +seek, on the borders of the coves, and in the creeks of the meadows, a +concealed and safe feeding-place during a coming storm. And many a time in +the autumn, after they had all passed down for the season, when the +indications of an approaching storm were clearly visible at nightfall, +have I waited for them to return, on the eastern margin of a bend in the +cove, on the eastern side of a creek, to shoot them, though invisible, by +shooting across the head of the wake, which they made upon the water in +alighting, and from which the few remaining rays of twilight that came +from the western sky were reflected. + +"But I am far from being singular in this. That page is more extensively +read than is generally supposed. Many plain, unassuming men--farmers, +shipmasters, and others within the circle of my acquaintance--know more, +practically, of the weather than the most learned closet-theorist, or the +most indefatigable recorder of its changes. Every one, by studying the +page of nature above him, as he would the page of any other science, and +testing, by observation, the numerous theories invented to account for the +varied phenomena, may learn much, very much, that will be useful and +interesting to him, and which he can never learn from books, or +instruments, or theories alone." + +"Well," said my friend, "I am too far advanced in life, as are many +others, to commence such observations, and you must publish." + +I demurred, and he insisted. + +"It is difficult to spare the time; and I can not neglect my profession," +I urged. + +"Where there is a will there is a way," he replied. + +"It is difficult to make one's self understood without many +illustrations." + +"Very well, they are easily obtained." + +"But they cost money, and it is said 'science will not pay its way' like +fiction and humbug." + +"That," said he, "is a libel--such science will. Every one is interested +in the weather--all talk about it--and thousands would carefully observe +it, if they could be correctly guided in their observations." + +"I may get into unpleasant controversy." + +"Suppose you do; you can yield your position if wrong, and maintain it if +right, and _magna est veritas_." + +"But I may be mistaken in some of the views to which it will be necessary +to advert, if I attempt to systematize the subject." + +"Be it so--your mistakes may lead others to the discovery of the truth. +Besides, the weather is _common property_, and every one has a right to +theorize about it, or to talk about it, as they please--even to call a +stormy day a pleasant one, or make any other mistaken remark concerning +it; and every other person is entitled to a like latitude of reply. And +further," said he, with some emphasis, "no important observation, in +relation to a subject of such interest, should be lost; and, if you have +observed one new fact, or drawn one new and just inference from those +which have been observed by others; and especially if, from observation +and reading, you can deduce from the phenomena an intelligible, +_observable, general system_, it is not only your right, but duty, to make +it known. Such a knowledge of the true system is greatly desired by every +considerate man." + +To my friend's last argument I was compelled to yield. I could make no +reply consistent with the great principles of fraternity, which I shall +ever recognize. The promise was given. My friend went on his way, and I +went to the daguerreotypist to procure a copy of the then appearance of +the sky, as the first step toward its fulfillment. The fulfillment of that +promise, reader, you will find in the following work. It was commenced as +an article for a magazine, but it has grown on my hands to a volume. +Justice could not well be done to the subject in less space. It has been +written during occasional and distant intervals of relaxation from +professional avocations, or during convalescence from sickness, and it is, +for these reasons, somewhat imperfect in style and arrangement. But I have +no time to rewrite. There is much in it which will be old to those who +read journals of science, but new to those who do not. There is more which +will be new to all classes of readers, and may, perhaps, be deemed +heretical and revolutionary by conservative meteorologists; yet I feel +assured that the work is a step in the right direction--that it contains a +substantially accurate exposition of the Philosophy of the Weather, and +valuable suggestions for the practical observer. + +I have inserted my name in the title-page, contrary to my original +intention, and at the suggestion of others; for I have no scientific +reputation which will aid the publisher to sell a copy. Nor do I desire to +acquire such reputation. It can never form any part of my "capital in +life." Nor has it influenced me at all in preparing the work. I have aimed +to fulfill a promise, too hastily given, perhaps--to put on record the +observations I have made, and the inferences I have drawn from those of +others--to induce and assist further observations, and, if possible, of a +_general_ and _connected character_--and to impress those who may read +what I have written with the belief, that _they will derive a degree of +pleasure from a daily familiarity with, and intelligent understanding of, +the "countenance of the sky," not exceeded by that which any other science +can afford them_. + +I have examined, with entire freedom and fearlessness (but I trust in a +manner which will not be deemed censurable or in bad taste) the theories +and supposed erroneous views of others, for, in my judgment, the +advancement of the science requires it. Says Sir George Harvey, in his +able article on Meteorology, written for the Encyclopædia Metropolitana: + + "It is humiliating to those who have been most occupied in + cultivating the science of meteorology, to see an agriculturist or a + waterman, who has neither instruments nor theory, foretell the future + changes of the weather many days before they happen, with a precision + which the philosopher, aided by all the resources of science, would + be unable to attain." + +The admissions contained in this paragraph, in relation to the comparative +uselessness of instruments and theories, and the value of practical +observation, are both in a good measure true. And the time has come, or +should speedily come, when "_pride of opinion_," and "_esprit du corps_," +among theorists and philosophers, should neither be indulged in, nor +respected; and when their theories should be freely discussed, and rigidly +tested by the observations of practical men. Such measure, therefore, as I +have meted, I invite in return. Let whatever I have advanced, that is new, +or adopted that is old, be _as_ rigidly tested, and _as_ freely discussed. +Let the errors, if there be any--and doubtless there are--be detected and +exposed. Let the TRUTH be sought by all; and meteorology, as a PRACTICAL +SCIENCE, advance to that full measure of perfection and usefulness, of +which it is unquestionably susceptible. + + + + +TABLE OF CONTENTS. + + + PAGE + + CHAPTER I. + + Heat and moisture are indispensable to the fertillity of the + earth--Arrangements exist for their diffusion and distribution, + and all the phenomena of the weather result from their + operation--Heat furnished or produced mainly by the direct + action of the sun's rays--Manner in which it is diffused over + the earth--Other causes operate besides the sun's rays--The + earth intensely heated in its interior--Heat derived from the + great Oceanic currents, and the aerial currents which flow + from the tropics to the poles, and from magnetism and + electricity--Water distributed by an atmospheric machinery as + extensive as the globe--Evidences of this--Its distribution over + the continents of North America--Explanation of it--Source from + whence our supply of water is derived, and from which our rivers + return 1 + + + CHAPTER II. + + Our rivers return in the form of clouds, and in storms and + showers--Definition and character of storms--Differences in + the character of the clouds which constitute them--Nomenclature + of Howard--Its imperfections--New order of description--Low + fog--High fog--Storm fog--Storm scud--N. W. scud--Cumulus-- + Stratus--Cirrus--Compounds of the two latter--recapitulation in + tabular form 24 + + + CHAPTER III. + + Our rivers do not return from the North Atlantic--All storms and + showers move from the westward to the eastward--Seeming clouds + seen moving from the eastward to the westward are scud--They are + incidents of the storm, and not a necessary part of it--The + storm clouds are above them, moving to the eastward--Occasions + when this may be seen--Admitted facts prove it--Investigations + prove it--May be known from analogy--From the fact that there is + an aerial current pursuing the same course in which the storms + originate--Character of this current--Its influence upon our + country--Importance of a knowledge of its origin, cause, and the + reciprocal action between it and the earth--To this end necessary + to go down "to the chambers of the South" 43 + + + CHAPTER IV. + + The trade wind region--Its extent and arrangements--Its belt of + daily rains and movable character--The trade winds--The extra + tropical belt of rains--Connection between them and their annual + movements--The counter-trades--Their origin and situation--One + of them constitutes our aerial current--It originates in the + South Atlantic as a surface-trade--Anomalies of the trade wind + region--Dry seasons--Humboldt's description of them--Exist where + the surface trades are situated--The rainless countries-- + Concentrated counter-trade--Monsoons--Received theory in relation + to them a fallacy--Cause of the great central phenomena-- + Calorific theory a fallacy--Land not hotter under the belt of + rains, nor sea materially so--Theory should be abandoned 52 + + + CHAPTER V. + + The agent, magnetism--Its character and currents--Oxygen + magnetic--Precipitation at the belt of rains occasioned by + depolarization--Storms originate in this central belt, and move + toward the poles 82 + + + CHAPTER VI. + + Course and functions of the counter-trade--Ours come from the + South Atlantic--Reason why it can not come from the Pacific-- + Mistake of Mr. Redfield and Lieutenant Maury in regard to it-- + All our storms originate in it--Proofs of this--State of the + weather, whether hot or cold affected by it--Proofs of this--All + our surface winds are incidents of it, and due to its conditions + and attractions--Proofs of this--Character of the different + winds--Anomalies of Mr. Blodgett accounted for--Received theory + in regard to sea and land breezes a mistaken one--Proofs of + this--Peculiar character of the N. W. wind--Identity with the + winter Mexican northers--Character of the West India hurricanes-- + Of the thunder-gust--Of the tornado--Sundry particulars in + relation to the latter--Due to currents of electricity-- + Proportions of winds in different localities--Examination of the + work of Professor Coffin upon that subject--Examination of + Lieutenant Maury's theory of the monsoons 92 + + + CHAPTER VII. + + Height of the counter-trade in different latitudes--Cause of the + Calms of Cancer--Influence of mountains upon the counter-trade-- + Reports of Herndon and Gibbon--Focus of precipitation in the + extra-tropical belt north of its southern line--Evidences of + this--The elevation of the counter-trade above the earth varies + in the same latitude with the variations in the phenomena of the + weather--Temperature of the counter-trade--Rain dust, its origin + and indications--Volcanic ashes--How far they indicate its course + of progression--Question whether there is an eastern progression + of the body of the atmosphere above the machinery of distribution 179 + + + CHAPTER VIII. + + Important to understand the precise character of the reciprocal + action between the earth and the counter-trade--Connection + between the width and movements of the belt of inter-tropical + rains and the volume of the trades--Its peculiarities over + Africa, the Atlantic, and South America--The magnetic equator-- + Character of the storms which originate in the inter-tropical + belt indicate local magnetic action--Supposed influence of + volcanic action--Gulf Stream changes its position--This the + result of magnetic action--Alternating contrasts of heat and + cold, and rain and drought--Dr. Webster's history of the + weather--Spots upon the sun--Their character and influence--Cold + or warm periods during the same decade, and during different + decades--Connection between the spots and magnetic disturbances + and variations--Influence of the moon upon the weather--No + decisive inference to be drawn from these facts, and a more + critical examination necessary 204 + + + CHAPTER IX. + + Examination of existing theories--Calorific theory the prevailing + one--Lateral overflow of Professor Dove--Absurdity of his views + in relation to them--His theory of hurricanes--Its absurdity--A + new theory by Mr. Dobson--Three theories advanced by + meteorologists of this country--Professor Espy's theory--Mr. + Bassnett's theory--Mr. Redfield's theory--Extended examination of + the latter--His theory in relation to the fall of the barometer + contradictory in its character--Philosophy of the barometric + change--No aid to be derived from these theories 232 + + + CHAPTER X. + + Further inquiry in relation to the reciprocal action between the + earth and the counter-trade--Terrestrial magnetism, and what we + know of it--Its elements, and their variations--Their connection + with the variations of atmospheric condition--Magnetism acts + through its connection with electricity--Character of the latter + and its variations--Their connection with atmospheric conditions-- + Electricity as well as magnetism in excess over this country-- + Effects of it upon our climate--Closer consideration of the + atmospheric phenomena--Their diurnal changes and connections + compared with those of magnetism and electricity--Grouping of all + the diurnal variations--Particular and separate examination of + them--Classification of storms--Examination in detail of the + several classes and the primary influence of the earth or + counter-trade in relation to each 285 + + + CHAPTER XI. + + Prognostics 340 + + + + +THE PHILOSOPHY OF THE WEATHER. + + + + +CHAPTER I. + + +Heat and moisture are indispensable to the fertility of the earth. Without +suitable arrangements for their diffusion and distribution, and within the +limits of certain minima and maxima, it would not have been habitable, or +the design of its Creator perfected. These arrangements therefore exist, +and "while the earth remaineth seed time and harvest shall not cease." Few +and simple in their character, though necessarily somewhat complicated and +irregular in their operation, the ultimate result is always attained. A +beautiful system of compensations supplies the losses of every apparent +irregularity in one section or crop, by the abundance of others. + +From the operation of these few, simple, connected, and intelligible +arrangements for the diffusion of heat and the distribution of moisture +over the earth, result all the phenomena which constitute the weather; and +by studying them, and their operation, we may acquire an accurate +knowledge of its "_Philosophy_." + +The necessary heat is furnished, or produced, mainly by the direct action +of the sun's rays; and the most obvious feature in the arrangements for +its diffusion is that by which the sun is made to shine successively and +alternately upon different portions of the earth. Nothing animate or +organic could endure his burning rays, if they shone continuously or +vertically upon one point, or could exist without their occasional +presence. Hence the provision for a diurnal rotation, to prevent the +exposure of any portion of the globe to the action of those rays for +twenty-four consecutive hours, except for a limited period, and at a +considerable angle, in the polar regions. But the earth is spheroidal, and +a diurnal revolution would still leave that portion which lies under the +equator too much, and the other too little, exposed to the action of the +sun. This is obviated by an annual revolution of the earth around the sun, +and an obliquity of its axis, by reason of which the northern and southern +portions are alternately and, as far as the tropics vertically, exposed to +the sun; and it is made to travel (so to speak) from tropic to tropic, +producing summer and winter, and other important phenomena. + +This obliquity and consequent change of exposure are in degree precisely +what the wants of the earth would seem to require. If it was greater, the +sun would travel further north and south, but the alternate winters would +be longer and more severe. If it was less, the end would not be as +perfectly attained. + +The direct action of the sun's rays upon the earth, particularly those +portions which lie north and south of the tropics, is not the only source +from which the supply of heat is derived. Although there is a general +increase of heat in spring and summer when the sun travels north, and of +cold when he travels south in winter, yet there are frequent +irregularities attending both. Very sudden and great changes occur in each +of them. Frost sometimes, cool weather often, occurs in midsummer, and +considerable heat and tornadoes in midwinter. And ordinarily the maxima +and minima of each month and, indeed, of each week are widely apart. Even +in the polar regions, in midwinter, _where the sun does not shine at all_, +the same moderating changes with which we are conversant occur in degree. +An extract or two from the register found in Dr. Kane's narrative of the +"Grinnell Expedition" will illustrate this. + + JANUARY 1851, (LATITUDE ABOUT 74°, LONGITUDE ABOUT 70°). + + Date. Wind. Force. Ther. Bar. Sky and Weather. + + Jan. 3 calm -26.1 29.62 blue sky, m. + " 4 W. gent breeze -21.3 29.53 blue sky, + detached clouds, m. + " 5 W. by N. gent breeze -3.9 29.59 blue sky, m., + clouded over. + " 6 W. by S. light breeze -0.8 29.67 clouded over, m., + snow. + " 7 W. gent breeze -14.4 29.96 blue sky, detached + clouds, m. + " 8 W.S.W. light air -21.2 30.14 blue sky, m. + " 29 W.N.W. light air -18.9 30.19 blue sky. + " 30 NW. by W. light air -13.5 30.17 clouded over, m. + " 31 NW. by W. gent breeze -4.4 29.35 clouded over, snow. + Feb. 1 W. light breeze -11.7 29.27 cloudy, blue sky, m. + " 2 W. light air -25.1 29.62 blue sky, detached + clouds, m. + +These extracts are instructive. It will be seen that on the 3d of +January, when the sun had been absent some weeks, it was calm, the +thermometer stood at 26° below zero (the - or minus mark before the +figures indicates that), and the barometer at 29.62, with blue sky, +somewhat misty or hazy--(the letter "m." standing for misty or hazy)--a +state of the air which existed most of the time when it did not snow or +rain, and therefore is of no importance in this connection. The next day +the thermometer began to rise, and the barometer to fall. On the 5th it +clouded over, and the thermometer rose rapidly, and on the 6th it had +risen more than 25°, and snow fell. On the 7th it cleared off, the +thermometer fell rapidly, and the barometer rose. On the 8th the +thermometer had fallen to 21° below zero, and the barometer had risen to +30.14. Another instance, in all respects similar, occurred the latter part +of the month. We shall see hereafter that these changes are precisely like +those which occur with us, and every where. That, as in the polar regions, +and whether the sun be present or absent, or obscured by clouds, and by +night as well as by day, the changes from warm to cold and from cold to +warm are sudden and great, and that the latter are connected with the fall +of rain and snow--that every where in winter it _moderates to storm_. + +Many other instructive instances, especially in relation to the great +difference in the seasons in our own country, and upon the same parallels +elsewhere, might be cited if it were necessary. But they will more +appropriately appear in the sequel. + + +[Illustration: Fig. 1. + +In the above cut the isothermal lines are Centigrade. The zero of the +Centigrade thermometer is the freezing point of water, or 32° of +Fahrenheit. The boiling point of water is 100° Centigrade, or 212° +Fahrenheit. A degree of Centigrade is equal to one degree and four-fifths, +Fahrenheit. The 0° line of the cut, therefore, is 32° of Fahrenheit--the +line of 5° above is 41° Fahrenheit--the line of 5° below is 23° +Fahrenheit, and so on. The reader, who is not familiar with the difference +in the scale of the thermometer, is desired to remember this; for we shall +make occasional extracts in which the temperature is given in the +Centigrade scale.] + + + +The cause of those irregularities, especially in the same seasons of +different years, and when very great, is often sought and supposed to be +found in the presence or absence of spots on the sun, ice floes and bergs +in the Atlantic, etc., etc. But neither the spots, nor ice, nor other +local causes produce them. The cause will be found in the character of the +arrangements we are considering, and the irregular action of the power +which controls them. + +Nor is the temperature of the northern hemisphere, north of the tropics, +equal in the same latitudes. Very great diversities exist in the "annual +mean" as well as the "mean" of the different seasons. Accurate +observations at many points have enabled men of science to demonstrate +this by drawing isothermal lines (_i. e._, lines of equal average annual +heat) from point to point around the earth, which show at a glance these +differences. The annexed cut is a polar projection of the isothermal lines +of the northern hemisphere, as far down as the tropic, copied from +Kaemtz's Meteorology. The dotted lines show the parallels of latitude, the +dark lines the isothermal lines, or lines of equal annual average +temperature. The reader is desired to observe how rarely they correspond +with the parallels of latitude, and how they fall below in a few +instances, and in others with great uniformity rise almost to the pole. + +Take, for example, the isothermal line of 0 or zero--that is, the line +where the mean or _average_ height of the thermometer _for the year_ is at +zero. At Behring's Straits this line is a little below the Arctic circle, +or the parallel of 66.30 north latitude. Passing east over North America, +it descends into Canada, almost to Lake Superior, and to about the 50th +parallel: that is to say, it is on an average during the year as cold on +our continent at the 50th parallel as it is near Behring's Straits at the +65th parallel. Passing east, the line of zero rises again over the +Atlantic Ocean until, in the meridian of Spitzbergen, it reaches, within +the Arctic circle, up almost to the 75th parallel. So, too, the isothermal +of 5° below zero, which is below the 60th parallel in Siberia, rises in +the North Sea, above Behring's Straits, to the parallel of 75°, descending +on the continent in North America to the 55th parallel, and rising again +almost to the pole at Spitzbergen, to descend again in Siberia, while the +isothermals of 10° and 15° below zero, which in North America are but just +above the latitude of 60° and 75° respectively, ascend abruptly +_surrounding the magnetic pole_, and _falling short of the geographical +one_. Let this projection of the lines of equal temperature, and +particularly the situation of the magnetic poles, be studied well, for we +shall recur to it hereafter in illustration of many important portions of +our subject. + +It is apparent from these facts, and were it necessary might be rendered +still more so by referring to others, that other causes operate in the +distribution of heat over the earth besides the direct action of the sun's +rays upon it. Doubtless very considerable allowance is to be made for the +difference of seasons, and difference during the same season upon the +land and upon the ocean; in mountainous countries and level ones. But +making every allowance for them, the fact that other causes have a +_controlling_ influence in producing the deviations still remains most +obvious. Neither the difference of temperature between the land and the +ocean, or land surfaces of unequal elevations, will account for the +elevation of the isothermal lines on different portions of the ocean, or +their extension around the magnetic poles. + +Returning to a consideration of the arrangements for the diffusion of +heat, we observe: First, that the earth itself is intensely heated in its +interior. This is inferred, and justly, from the fact that the thermometer +is found to rise about one degree for every fifty-five feet of +descent--whether in boring artesian wells, exploring caves, or sinking +shafts in mines. It is demonstrated, also, by the existence of hot springs +and the action of volcanoes. Heat is supposed to be conducted from the +center toward the surface every where, but with difficulty and slowly. It +is also supposed to be conducted from the tropical regions toward the +poles. Such is the opinion of Humboldt. (Cosmos, vol. i. p. 167.) + +Probably it reaches the surface and exerts an influence, also, upon the +weather through the ocean, and by heating it in its greatest depths. +Little attention has been paid, so far as I am informed, to the question +how far the ocean is thus heated in _tropical latitudes_. Doubtless a +portion of the warmth of the ocean there is derived from that source, and +it has its influence in changing the temperature of the deep-seated cold +polar currents of, the great oceans. Perhaps it may yet be found that the +icebergs are detached by it in the polar seas--the observations of Dr. +Kane point to such a result. (Grinnell Expedition, p. 113, and also chap. +48.) + +Little need be said of the inconsiderable quantities of heat supposed to +be derived by radiation from the stars, the planets, and from space. If +any such are derived they are too inconsiderable to be of importance in +this inquiry. + +Heat is also carried, and in quantities which exert very considerable +influence upon the weather, from the tropics to the poles by the great +oceanic currents which flow unceasingly from one to the other. + +The most important of these with which we are acquainted is the Gulf +Stream of the Atlantic. Gathering in the South Atlantic, and passing north +through the Caribbean Sea and the Gulf of Mexico, it issues out through +the Bahama Channel, and flows north along the eastern coast of the United +States, but some distance from it, to Newfoundland, and from thence +continuing to the north-east and spreading out over the surface of the +ocean--a portion of it mingling with the waters of the North Atlantic in +passing--it flows up on the western coast of Europe, around the Faroe +Islands, and Spitzbergen, to the polar sea; passing around Greenland, and +perhaps through its Fiords, it descends again through the sounds and +channels of the Arctic regions into Baffin's Bay, and through Davis's +Straits, burdened with the icebergs and floes of the polar waters, to +return again to the South Atlantic. For reasons which will appear in the +sequel, it has comparatively little influence upon the weather of the +United States. Western Europe, however, Greenland, the islands which lie +in its course, and the polar seas, are most materially influenced. +Although not the only cause, it has very much to do with the remarkable +elevation of the isothermal lines over the Northern Atlantic, and upon +Western Europe, as seen upon the map. + +A like oceanic current exists in the Pacific Ocean, the influence of which +may also be traced upon the map by the elevation of the isothermal lines +at the northern extremity of that ocean, and upon the north-west coast of +North America. A vast amount of heat is transported from the tropical to +the temperate and frozen regions of the earth by these great oceanic +currents. + +Another supply is derived from aerial currents which flow from the tropics +toward the poles. These currents exist every where over the entire surface +of the earth, but in more concentrated volumes along the great "lines of +no variation," and greater magnetic intensity, on the western side of the +great oceans, over the eastern portions of the two continents of North +America and Asia. Not, as meteorological writers suppose, in the upper +portions of the atmosphere, having risen in the trade-wind region and run +off at the top toward the poles by force of gravity, but near, and +sometimes in contact with the earth. The influence of these aerial +currents upon the temperature of the atmosphere, and in producing the +phenomena we are to consider, is exceedingly important. We shall have +occasion to examine them with great care and minuteness under another +head, for upon them, more than any other portion of the arrangements, +depend not only the diffusion of heat, but also the distribution of +moisture. + +Still another supply of heat, during the sudden changes, at least, is +produced by the action of terrestrial magnetism and electricity. Very +great progress has been made within a short period, in the investigation +of the nature of these agents. The identity, or at least intimate +association or connection of heat, light, electricity, and magnetism, +always suspected, has been in various ways, and by a variety of +experiments demonstrated. The influence of magnetism if distinct from +gravitation, is second only to that; and its agency in producing the +phenomena we are considering is primary and controlling. We will only, in +this connection, ask the reader to note the situation of the north +magnetic poles (for there are two of them); the manner in which the +isothermal lines _surround_ them; the fact that they are _poles of cold_, +_i. e._, that it is colder there than even to the north of them. We shall +recur to this part of the subject again. + +Such, briefly considered, are the principal arrangements by which heat is +diffused over the earth. + +Equally marked by infinite wisdom, and equally interesting and important, +are the arrangements by which moisture is distributed. Doubtless the +general belief is that this is a simple process; that water evaporates +and rises till it meets a colder stratum of atmosphere, and then condenses +and falls again; or that, according to the Huttonian theory, currents of +air of different temperatures mingle and equalize their heat, and the +aggregate mass when equalized in temperature is cooler, and therefore is +unable to hold as much moisture in solution as the most heated portion +had, and the excess falls in rain. But the process is by no means so +simple, nor is heat the sole or most powerful agent concerned in it. +Currents of air do not mingle, but stratify. Evaporation from the surface +of any given portion of the earth outside of the tropics does not alone +supply that portion with rain. _Vast and wonderful, coextensive with the +globe itself, and perfectly connected, is the machinery by which that +supply is furnished even to the most inconsiderable portion of its +surface._ + +Take your map of North America and note, in this respect, its +peculiarities. It extends from the Isthmus of Darien to the Arctic +regions, and from the 65th to the 160th meridian of west longitude from +Greenwich, and has upon its surface a type of every climate in the world. +For the purpose of simplifying and illustrating the matter in hand, let us +divide it into five sections. Let the first section embrace Central +America and Southern Mexico, south of 28°; the second, Northern Mexico and +Southern New Mexico, California, etc., between the parallels of 28° and +32°; the third, Northern California, Utah, Southern Oregon, and Western +New Mexico, north of the parallel of 32°; the fourth, the entire +continent north of 42°; and the fifth, the eastern United States, east of +the meridian of 100°. These divisions are not intended to be entirely +accurate in their separation, but substantially so for the purpose of +illustrating the differences which exist in each. + +The accompanying diagram shows approximately, by dotted lines, the +divisions. + + +[Illustration: Fig. 2.] + + +Now let us see in what a diverse manner, and to what a different extent, +they are severally supplied with moisture. + +Central America and Southern Mexico lie within the tropics--their rains +are tropical rains. The season is divided into wet and dry, as are the +seasons of all tropical countries which are not rainless. During the rainy +season it rains a portion of nearly every day, and during the dry season +the sky is clear, the air is pure, and rain seldom falls. + +All around the earth within the tropics, over the land and over the sea, +there is a belt of almost daily rains, varying in width, north and south, +in different sections, but averaging about five hundred miles. This belt +of daily rains is formed at and by the meeting of N. E. and S. E. trades, +and travels north and south with them, as they do with the sun, +_encircling the globe_. By this narrow belt a portion of the earth's +surface, an average of some 35° of latitude, is supplied with moisture. +Wherever it is situated at any given period, the tropical rainy season +exists; and when it is absent in its northern or southern transit, the dry +season prevails. Southern Mexico is within the range of this moving belt, +and in its course to the northward with the sun, in our summer from May to +October, it arrives over, and covers that country with a rainy season. +When the sun returns to the south, taking with it the trades and this belt +of tropical rains, that portion of Mexico is without rain, and dry, and so +continues until the rainy belt returns in the following year. While the +belt is over Southern Mexico it is nearly all _precipitation_, and there +is little _evaporation_; while that belt is _absent_ it is all +_evaporation_, with little or no _rain_. Surely this is not consistent +with the prevailing belief of simple evaporation, ascent to a colder +stratum, commingling, and condensation, and rain. Southern Mexico at least +is not supplied by mere evaporation from its surface, and must therefore +form an exception to that belief, and to the Huttonian theory. + +But we shall recur again to the peculiarity of distribution within the +tropics. + +Turn now for a brief space to Northern Mexico, Southern New Mexico, and +Southern California. In Northern Mexico, Southern New Mexico, Utah, and +California, between the parallels of 28° and 32°, and particularly west of +the mountain ranges, we find an almost rainless region, sterile and +worthless, resembling that which is found upon nearly the same parallels +of north latitude in Northern Africa, Egypt, Arabia, Beloochistan, +Afghanistan, and North-western India; and in corresponding latitudes south +of the Equator, in Peru, a portion of Southern Africa, and the northern +and middle portions of New Holland. Why Northern Mexico and the other +countries named are thus sterile and comparatively rainless, we shall see +hereafter, when we examine critically the machinery of distribution as it +operates within the tropics. It is the fact that it is thus sterile and +rainless to which we desire to call attention in this place. + +Mr. Bartlett thus describes it: + + "On leaving the head waters of the Concho, nature assumes a new + aspect. Here shrubs and trees disappear, except the thorny chaparral + of the deserts; the water-courses all cease, nor does any stream + intervene until the Rio Grande is reached, three hundred and fifty + miles distant, except the muddy Pecos, which, rising in the Rocky + Mountains, near Santa Fé, crosses the great desert plain west of the + Llano Estacado, or Staked Plain. + + "From the Rio Grande to the waters of the Pacific, pursuing a + westerly course along the 32d parallel, near El Paso Del Norte, there + is no stream of a higher grade than a small creek. I know of none but + the San Pedro and the Santa Cruz--the latter but a rivulet, losing + itself in the sands near the Gila--the other but a diminutive stream, + scarcely reaching that river. At the head-waters of the Concho, + therefore, begins that great desert region, which, with no + interruption save a limited valley or bottom-land along the Rio + Grande, and lesser ones near the small courses mentioned, extends + over a district embracing sixteen degrees of longitude, or about a + thousand miles, and is wholly unfit for agriculture. It is a + desolate, barren waste, which can never be rendered useful for man or + beast, save for a public highway."--_Bartlett's Personal Narrative_, + vol. i. p. 138. + +Turning now to Central and Upper California, and Utah, and Southern +Oregon, we find still another peculiarity. Like Southern Mexico, they have +a rainy and dry season, but at a different period, and for a different +reason. The dry season of California, etc., is the summer of the northern +hemisphere, and her rainy season the winter. _California_ is, therefore, +_dry_ when Southern _Mexico_ is _wet_, and _vice versâ_. The belt of rains +which supplies California with moisture during her rainy seasons is the +belt of _extra-tropical_ rains, which extends from the northern limit of +the north-east trades to the poles, encircling the earth. The southern +edge of this extra-tropical belt is _carried up_ on the western coast of +America, and in that portion of the continent in _summer_, when the sun +and trades, and the inter-tropical rainy belt travel to the north, and +uncover California, etc., leaving them without rain for a period of about +six months. + + +[Illustration: Fig. 3. IN SUMMER.] + + +As the sun, with the trades, travels south, the southern edge of the belt +of extra-tropical rain follows, and covers California, etc., again +extending gradually from the north to the south, and thus their wet +season returns. The annexed diagrams by the shading will show the +situation of the rainy belts which cover Mexico, Utah, New Mexico, and +California in summer and winter, and that the belts of rains are entirely +distinct and different in character. + + +[Illustration: Fig. 4. IN WINTER.] + + +Here again in this section of the continent, as in Mexico, evaporation is +going on for six months of the year, and were it not for the return of the +belt of rains from the north, in the fall, would go on for the entire year +without precipitation; and for the other six months precipitation is +vastly in excess. Nor can this be reconciled with, or explained by, the +Huttonian or any other received theory of rain. Here again it is obvious +that evaporation alone, however great or long continued, will not furnish +the evaporating section with rain. + +The northern portion of the continent lies beneath the zone of +extra-tropical rains, and north of the northern limit of the N. E. +trades--is never uncovered from it, and has no distinct rainy or dry +season, although more rain falls at certain periods, and in certain +localities, than at others. The climate of that part of Oregon which lies +upon the Pacific, and the character of its rains, resemble those of +North-western Europe, and will be further explained hereafter. + +Coming to the portion of the continent which we occupy, the 5th section, +we find it different still--a most favored region. Portions of it--Eastern +Texas, for instance--are upon the same parallels of latitude as the +rainless regions of Northern Mexico, etc. Eastern Texas, however, is not +rainless. Other portions are upon the same parallels as California, etc., +yet have no distinct rainy and dry season. We repeat, this section is a +most favored region--without a parallel upon any portion of the earth's +surface, except, in degree, in China and some other portions of Eastern +Asia. + +It is not only without a distinct rainy and dry season, but it is watered +by an average, annually, of more than forty inches of rain, while Europe, +although bounded on three sides by seas and oceans, and apparently much +more favorably situated, receives annually an average of only about +twenty-five--if we except Norway, and one or two other places, where the +fall is excessive. The distribution of this supply of moisture over the +United States is, in other respects, wonderful. Iowa, in the interior of +the continent, far away from the great oceans, on the east or west, or the +Gulf of Mexico on the south, receives fifty inches; some ten or fifteen +inches more than fall upon the slope east of the Alleghanies, and +contiguous to the great Atlantic (from which all our storms are, +erroneously, supposed to be derived), and the average over the entire +great interior valley is about forty-five inches, falling at all seasons +of the year. + +Observe, then, by way of recapitulation: Southern Mexico has a rainy +season furnished by the belt of _inter_-tropical rains, which _travels up +over it from the south_ in summer. California has a rainy season, which is +furnished by the _extra_-tropical belt of rains, which travels _down from +the north_, and covers it in winter. Northern Mexico and the adjoining +regions west of the 100th meridian are between the limits of the two, and +neither travels far enough to reach them, except for brief and uncertain +periods; they are comparatively rainless; while the eastern portion of +the continent, _in all latitudes_, unlike the others, is without a +distinctly marked dry season, or a rainless region, and with the exception +of occasional droughts, is abundantly supplied with rain at all seasons of +the year. + +And now, what is the explanation of all this? What produces the +extra-tropical belt of regular rains surrounding the earth, north of the +parallel of 30° north, in some places, and 35° in others, extending to the +pole, with its southern edge traveling up ten or more degrees in summer, +leaving large portions of the earth subject to a dry season; and back +again in the winter to give them a rainy one? What produces the narrow +belt of inter-tropical rains, encircling the earth; traveling up and down +every year over an average of 35° of latitude, supplying every portion of +it alternately with rain? And what connects the two together over the +eastern portion of North America, so as to leave no distinctly marked wet +and dry season, and no rainless and sterile portion there? Are all these +the result of simple evaporation, ascent to a colder region, condensation, +and descent again? Demonstrably not. Of the forty inches which fall +annually upon the middle and eastern portions of the United States, an +average probably of one-half or twenty inches, runs off by the rivers to +the ocean, or is carried away eastward by the westerly and north-westerly +evaporating winds. The same is true, in degree, of the rain which falls +upon the other portions. Evaporation, therefore, could not keep up the +supply. From whence, then, does it come? this twenty inches, thus lost by +the rivers and winds, and with such wonderful regularity every year. + +"All the rivers run into the sea, yet the sea is not full. _Note the place +whence the rivers come, hither they return again._" + +But how is it that they thus return with such wonderful regularity, in a +narrow traveling belt of daily rains within the tropics, and a movable +belt of irregular rains without the tropics, extending to the poles, +leaving a space on each side of the equator encircling the earth in like +manner (except at two points, _viz._, Eastern Asia and Eastern North +America), from which they do not go, and to which they do not return, and +which is almost entirely unfurnished with rain? And all this without any +relation, whatever, to the contiguity of the oceans? Obviously this is not +the work of mere evaporation, or of the accidental or irregular +commingling of winds with different dew points, or quantities of moisture +in solution, or accidental, irregular changes of barometric pressure. _It +is one vast, wonderful, connected, and regular system--co-extensive with +the globe--necessary to the return of moisture from the oceans upon the +most inconsiderable portion of it, and to the condensation of the local +moisture of evaporation; and by it the waters are returned from the oceans +as regularly and bountifully upon the far interior of the great continents +in the same latitudes, as upon the "isles which rest in their bosoms."_ + + + + +CHAPTER II. + + +Before proceeding to an examination of this connected atmospheric +machinery, and an investigation of the particular ocean from which our +rivers return, it may be well to look at the form in which they appear to +return, that we may have a clear understanding of terms. + +They seem to return in the form of clouds, and in storms and showers, +although, in truth, they return in regular, uniform, ordinarily invisible +currents, and the storms and showers are but condensations in, and +discharges from portions of those currents, aided by the local moisture of +evaporation. + +The term _storms_, seems to be used by European meteorologists to denote +what we term thunder showers or gusts, and tornados; while what we call +storms are denominated by them regular rains. As the terms are extensively +in use in this country, we must adhere to the meaning attached to them +_here_ rather than _there_. + +Storms with us, then, are regular rains of from six to forty-eight or more +hours' continuance: generally without lightning, or thunder, or gusts, and +usually with wind of more or less force, from some easterly point. They +are called north-east storms, or south-east storms, according to the +point from which the surface winds blow. Practically we shall find that +this distinction is of some importance, for the north-east storms are the +longest, lasting generally twenty-four hours, or more, while the +south-east ones seldom, if ever, continue as long. + +These storms extend over a considerable surface, rarely less than one +hundred miles in one direction or another, and sometimes fifteen hundred, +or more. Distinct showers cover but a small surface, sometimes not more +than forty to one hundred rods, as in the tornado, and rarely more than +ten miles. Belts of showers, each new one forming a little more to the +south, often, in summer, pass across the country, following each other in +succession; and these belts may be of considerable width, say thirty to +one hundred and fifty miles. + +The clouds which constitute the storms and showers differ in appearance +and character, as well in the active as in the forming state. Clouds are +of distinct characters, alike, substantially, every where under like +circumstances; and a distinct nomenclature has been applied to them by Dr. +Howard, of London. He notes three kinds of primary clouds: _viz._, cirrus, +stratus, and cumulus; and inasmuch as the boundary line between them is +not very distinct, certain compounds of the three, _viz._: cirro-stratus, +cirro-cumulus, and cumulo-stratus. This nomenclature is every where +received, and portions of it are of great practical importance. + +The three principal descriptions of cloud, _viz._: the cirrus, the +stratus, and the cumulus, we have very much as they have in Europe, and +doubtless as they exist every where outside of the tropics. The nimbus, +another cloud described by him, is not distinct from the cumulus or +stratus. An isolated, limited thunder-shower in a clear sky, presents the +appearance of a nimbus, as shown in the cuts, but the basis of it is a +cumulus, and it differs from an ordinary fair-weather cumulus merely in +the dark and fringe-like appearance of the rain as it is falling from its +lower surface, and sometimes in the existence of a stratus above and in +connection with it. A similar form is often assumed by the peculiar clouds +of the N. W. winds in March or November, when they assume the form of +_squalls_, and drop flurries of snow. The nimbus, therefore, is not a +distinct cloud, but an appearance which the cumulus, stratus, or +cirro-stratus has in a stormy or showery state, and does not deserve a +distinct name. It is but a cumulus, or a stratus, or cirro-stratus +dissolving in snow or rain. It is important that this term should be +abandoned. It tends to confuse and prevent a clear understanding of the +difference in the character of the clouds, and in relation to which +precision is both difficult and desirable. + +The figures on pages 27 and 29, show the different kinds of clouds as +designated by Howard. They are copied from the engravings in the sixth +edition of Maury's "Sailing Directions." + + +[Illustration: Fig. 5.] + +[Illustration: Fig. 6.] + + + Figure 5. + The cirrus is indicated by 1 bird. + The cirro-cumulus by 2 " + The cirro-stratus by 3 " + The cumulo-stratus by 4 " + + Figure 6. + The cirrus by 1 " + The cumulus by 3 " + The stratus by 2 " + The nimbus by 4 " + +How far these representations correspond with the actual appearance of the +different compound forms in England, I can not say. But although they +convey a _general_ idea, _they are not sufficiently accurate for practical +illustration or observation here_. Indeed Howard himself has omitted from +his last edition his plate of the clouds, assigning as a reason, "that the +real student will acquire his knowledge in a more solid manner by the +observation of nature, without the aid of drawings, and that the _more +superficial are liable to be led into error by them_." The collection of +forms in the cuts _does not contain some very important ones_, and +contains some which are not distinct forms; but they may aid us somewhat +in this inquiry, and, therefore, I have copied them. It is well, also, for +the reader to have the generally received description before him. + +But for the purpose of _practical_ illustration hereafter, and greater +precision, I shall follow a somewhat different order in describing them, +and introduce two forms of _scud_ quite as important, practically, as any +other. + +First, then, commencing at the earth, we have what may be properly termed +_fog_, or low fog. This forms, in still clear weather, in the valleys, and +over the surface of the rivers and other bodies of water, during the +night, and most frequently the latter part of it, and is at its acmé at +sunrise, or soon after, limiting vision horizontally and perpendicularly, +and dissolving away during the forenoon. It is rarely more than from two +to four hundred feet in height at its upper surface, and often much less, +and is composed of vesicular condensed vapor, sometimes sufficiently dense +to fall in mist, and is doubtless in composition substantially what the +clouds are in the other strata of the atmosphere, as observed by us, or +passed through by aeronauts. I have never seen it carried up to any +considerable height into the other strata by any of the supposed ascending +currents, to form permanent clouds, and shall have occasion to allude to +the fact in another connection. It disappears usually before mid-day, and +has, when thus formed, no connection with any clouds which furnish rain. + +To this Dr. Howard originally gave the name of stratus, and so it is +represented upon the cut; but the latter term may be with greater +propriety applied to the smooth uniform cloud in the superior strata from +which the rain or snow is known to fall, and I shall retain and so apply +it. + +The next in order, ascending, is high fog. This is usually from one to +two thousand feet in height at its lower surface. It forms, like low fog, +during the night and in still weather; and is rarely, if ever, connected +with clouds which furnish rain. It breaks away and disappears between ten +and twelve in the forenoon, usually passing off to the eastward. This fog +is most commonly seen in summer and autumn, particularly the latter, and +unless distinguished from cloud will deceive the weather-watcher. It is +readily distinguishable. Although often very dense, obscuring the light of +the sun as perfectly as the clouds of a north-east storm, it differs from +them. It forms in still clear weather, is present only in the morning, is +perfectly uniform, and, before its dissolution commences, without breaks, +or light and shade, or apparent motion, and unaccompanied by scud or +surface wind. The storm clouds are never entirely uniform, or without +spots of light and shade, by which their nature can be discerned, and +rarely, when as dense as high fog, without scud running under them and +surface winds. + +There is another fog still, connected with rain storms, but it does not +often precede them; occurring at all seasons, but most commonly in +connection with the warm S. E. thaws and rains of winter and spring; and +which usually comes on _after_ the rain has commenced and continued for +awhile, and the easterly wind has abated; occupying probably the entire +space from the earth to the inferior surface of the rain clouds or +stratus. Practically this does not require any further notice. It is an +_incident_ of the storm. When formed it remains while the storm clouds +remain, and passes off with them. It is sometimes exceedingly dense in +February and March, when it accompanies a thaw, and if there is a +considerable depth of snow, it has the credit of aiding essentially in its +dissolution. + +Mingled with the smoke of London, it produced there the memorable _dark +day_ of the 24th of February, 1832, and at various other times has +produced others of like character. (See Howard's Climate of London, vol. +iii. pp. 36, 207, 303.) These fogs have been so dense there that every +kind of locomotion was dangerous, even _with lanterns, at mid-day_. + +The next in order, ascending, are the storm scud, which float in the +north-east or easterly, south-east or southerly wind, before and during +storms. + +These, as the reader will hereafter see, are, _practically_, very +important forms of cloud condensation--although they have found no place +in any practical or scientific description given of the clouds, and are +not upon the cuts. They are patches of foggy seeming clouds of all sizes, +more or less connected together by thin portions of similar condensation, +often passing to the westward, south-westward, north-westward, or +northward with great rapidity. Their average height is about half a mile, +but they often run much lower. They are usually of an "ashy gray" color. +The annexed cut shows one phase of them, from among many taken by +daguerreotype. The arrows pointing to the west show the scud distinguished +from the smooth partially formed stratus above. This view was taken a few +hours prior to the setting in of a heavy S. E. rain storm. It is a +northerly view. + + +[Illustration: Fig. 7.] + + +At about the same height, but in a _different state of the atmosphere_, +float the peculiar fair-weather clouds of the N. W. wind. They usually +form in a clear sky, and pass with considerable rapidity to the S. E. +Sometimes they are quite large, approaching the cumulus in form, and +white, with dark under surfaces, and at others, in the month of November +particularly, are entirely dark, and assume the character of squalls and +drop flurries of snow; and then resemble the nimbus of Howard. They assume +at different times and in different seasons, different shapes like those +of the scud, the cumulus, or the stratus. + + +[Illustration: Fig. 8.] + + +They form and float in the peculiar N. W. current which is usually a +fair-weather wind, and are never connected with storms. In mild weather +they are usually white, and in cold weather sometimes very black, and at +all times differ _in color_ from the ashy gray scud of the storm. This +variety is not represented upon the general cuts. The annexed diagram +shows one phase of them, but they are readily observable at all seasons of +the year, when the N. W. wind is prevailing; differing in appearance +according to the season. Let these, as well as the storm scud, be +carefully observed and studied by the reader, and let no opportunity to +familiarize himself with their appearance be lost. A brief glance at +each recurrence of easterly or north-westerly wind will suffice. + + +[Illustration: SUMMER CUMULI.] + + +The _cumuli_ appear in isolated clouds of every size, or in vast clouds +composed of aggregated masses, as the peculiar cloud of the thunder +shower. They form as low down as the scud or fair-weather cloud of the N. +W. wind, which, for convenience, I will call N. W. _scud_; and often in +violent showers, and particularly in hail storms, extend up as far as the +density of the atmosphere will permit them to form. Professor Espy thinks +he has measured their tops at an altitude of ten miles. Others have +estimated their height, when most largely developed, at twelve miles; but +it is very doubtful whether the atmosphere can contain the moisture +necessary to form so dense a cloud at that elevation. It is their immense +height, however, whether it be six, or eight, or ten miles, together with +the sudden and violent electric action, condensing suddenly all the +moisture contained in the atmosphere within the space occupied by the +cloud, which produces such sudden and heavy falls of rain or hail. As the +rain drops or hail, when formed at such an elevation, in falling through +the partially condensed vapor of the cloud must necessarily enlarge by +accretion from the particles with which they come in contact, and probably +also by attraction, their size when they reach the earth, though +frequently very considerable, is not a matter of astonishment. The cumulus +is represented in the general plate with sufficient accuracy to show its +peculiar character. + +In summer, when the air is calm, the weather warm, and no storm is +approaching, there is always, in the day time, a tendency to the formation +of cumuli. This tendency exhibits itself about ten o'clock in the +forenoon, and they gradually form and enlarge until about two in the +afternoon; and after that, if they do not continue to enlarge and form +showers, they melt away and disappear before nightfall. Sometimes in July +and August the atmosphere will be studded with them at mid-day, floating +about three-quarters of a mile from the earth (in a level country), gently +and slowly away to the eastward. At times it may seem as if they must +coalesce and form showers, yet they frequently do not, but gradually melt +away, as before stated. + +The cumulus is the principal cloud of the tropics, and is not often seen +with us except in summer, or when our weather is tropical in character. + +The engraving on the preceding page, shows a phase of these fair-weather +summer cumuli. + +The last in order occupying (with their compounds) the higher portions of +the atmosphere, are the cirrus and stratus. The cirrus is often the +skeleton of the other, and precedes it in formation. + +These are the proper clouds of the storm, in our sense of the term. While, +however, the cirrus remains a cirrus, it furnishes no rain. When it +extends and expands, and its threads widen and coalesce into cirro-stratus +and stratus, or it induces a layer of stratus below it, the rain forms. + +The following is Dr. Howard's description of cirrus: "Parallel, flexuous +or diverging fibers, extensible by increase in any or in all directions. +Clouds in this modification appear to have the least density, the greatest +elevation, and the greatest variety of extent and direction. They are the +earliest appearance after serene weather. They are first indicated by a +few threads penciled, as it were, on the sky. These increase in length, +and new ones are in the mean time added to them. Often the first-formed +threads serve as stems to support numerous branches, which in their turn, +give rise to others." + +The illustrations in the general cut are imperfect, and do not represent +the delicate fibers of the cloud, for it is a difficult cloud to +daguerreotype or engrave, but the representation is sufficiently accurate +to give the reader a general idea of the different varieties, and enable +him to discover them readily by observation. They are the most elevated +forms, always of a light color, and often illuminated about sunset by the +rays of the sun shining upon their inferior surface; the sun, however, +often illuminates, in like manner, the dense forms of cirro-stratus, and +the latter, from their greater density, are susceptible of a brighter and +more vivid illumination. + +The stratus is a smooth, uniform cloud--the true rain cloud of the storm; +often forming without much cirrus above, or connected with it. It may be +seen in its partially formed state in the bank in the west, at nightfall, +or in the circle around the moon in the night. When it becomes +sufficiently condensed, rain always falls from it, but in moderation. If +there be large masses of scud running beneath it for its drops to fall +through (especially as is sometimes the case, in two or more currents), +the rain may be very heavy. But more of this hereafter. + + +[Illustration: Fig. 10.] + + +The annexed cut shows the forming stratus, light and thin, passing to the +east, as indicated by the short arrows just before a storm, while the scud +beneath is running to the west. + +It was copied from a daguerreotype view, facing northwardly. + +Intermediate between the fibrous, tufted, cirrus, and the smooth uniform +stratus, there is a variety of forms partaking more or less of the +character of one or the other, and termed _cirro-stratus_. No single +correct representation of cirro-stratus as a distinct cloud, can be +given--but several varieties will be hereafter alluded to, under the head +of prognostics. Several modifications are represented with tolerable +accuracy upon the cuts. + +The cirro-cumulus is a collection in patches of very small distinct heaps +of white clouds; they are called fleecy clouds, from their resemblance to +a collection of fleeces of wool, and are imperfectly represented on the +general cut. They do not appear often, and are usually _fair-weather +clouds_. + +This form has none of the characteristics of the cumulus, and does not +appear in the same stratum. It was probably called cumulus because its +small masses are distinct, as are those of the ordinary cumulus. It occurs +in the same stratum as cirro-stratus, and properly belongs to that +modification. I retain the name inasmuch as the cloud is of some practical +importance. + +The cumulo-stratus is seldom seen in our climate, as it is represented in +the cut. Stratus condensation _above_, and in connection with cumulus +condensation, is not uncommon, but that precise form is rare. + +This, too, is practically of no consequence, and I shall take no further +notice of it. + +Recapitulating, I give (in a tabular form) the three principal strata and +their modifications, located with sufficient accuracy for illustration. +The clouds which are found in an upper or lower portion of a stratum are +so represented by the location of their names; those which appear at all +heights in the stratum, with the names across. The elevation is the +average one--although there is no limit to the cirrus above, except the +absence of sufficient moisture. It was seen by Guy Lussac, and has been by +other aeronauts, at an elevation of five miles, or more, when too delicate +to be visible below. + + +------------------------------------------------+ + | | 3 miles. + |Cirrus. | + | Cirro-cumulus. | + | Cirro-stratus. | + | | + Primary | { Cumulus extending up | + stratum. | { in violent showers. | + | | + | | + |Stratus. | + |------------------------------------------------| + | | 1-1/2 miles. + Scud & |N. W. scud. { Cumulus Storm scud. | + cumulus |Fair-weather { ordinarily and | + stratum. | { its base always. | + | | + |------------------------------------------------| + | | 1/2 mile. + Fog |High fog. Storm fog. | + stratum. | | + | Low fog at the surface of the earth. | + | | + +------------------------------------------------+ + +With the assistance of this table of elevations, and a careful +observation, the reader can soon become familiar with the forms of clouds +and their relative situations. + + + + +CHAPTER III. + + +Having thus taken a brief view of the different clouds, let us return to +the inquiry, from what ocean, and by what machinery, _our_ "rivers +return." + +Not wholly or mainly from the North Atlantic, although it lies adjacent to +us, and they often _seem_ to do so; for, first, all storms, showers, and +clouds, which furnish, _independently_, any appreciable quantity of rain +to the United States, and even adjacent to the Atlantic, or indeed to the +Atlantic itself, come from a westerly point, and pass to the eastward. +_This is a general, uniform, and invariable law, although there is in +different places, and in the same place at different times, some variation +in their direction; ranging in storms from W. by S. to S. S. W., and in +showers between S. W. and N. W., to the opposite easterly points of the +compass; the most general direction, east of the Alleghanies, being from +W. S. W. to E. N. E._ + +But do we not see, you inquire--at least those of us who live east of the +Alleghanies--that when it rains, the wind is from the eastward; and that +the _clouds_ follow the wind from the east to the west? You do indeed, +generally, in all considerable storms, observe that the wind blows from +some easterly point, and that _seeming_ clouds are blown by it to the +westward; but what you see, and call clouds, are not the clouds which +furnish the rain. Far above the seeming clouds you notice, directly over +your head when it rains or snows, are the rain or snow clouds, dense and +dark, passing to the eastward, how strong soever the wind may blow from +the quarter to which they tend, or any other quarter, between you and +them. What you see below them are _scud_. So the sailors call them, and so +I have termed them. It is a "dictionary name," and a good one, expressive +of a distinction between them and _clouds_. They are thin, and the sun +shines through them, although with some difficulty, when the rain clouds +above are absent or broken. _This east wind and the scud are not the +storm, or essential parts of it._ Storms occasionally exist, particularly +in April, without either. They are but _incidents_, _useful_, but not +_necessary incidents_, as all surface winds are. + +If you could see a section of the storm, you would see the rain cloud +above, moving to the east, and the scud beneath running to the west, as +indicated by the arrows in the cut on page 40. Opportunities frequently +occur when these appearances may be seen. Storms are sometimes very long, +a thousand miles, perhaps, from W. S. W. to E. N. E., and not more than +one to three hundred miles wide from S. E. to N. W., and their sides, +particularly the northern ones, regular, and without extensive partial +condensation. Then the storm cloud above, moving to the eastward, and the +scud running under to the westward, may be seen as in the cut. + +So they may be seen before, at the commencement, and at the conclusion of +easterly storms, in a majority of cases, and the reader is desired to +notice them particularly as opportunities occur. + +The term _running_, too, is a very expressive one, used by sailors as +applicable to _scud_. For while the forming or formed storm clouds may be +moving moderately along, at the rate of twelve to fifteen or twenty miles +an hour, from about W. S. W. to E. N. E., the scud may be running under +them in a different direction--opposite, or diagonal, or both--at the rate +of twenty, fifty, sixty, and, in hurricanes, even ninety miles an hour. +You have doubtless seen these scud running from N. E. to S. W., and +without dropping any moisture, a day or sometimes two days, before the +storm coming from the S. W. reached the place where you were; and then, +sometimes the storm cloud slipped by to the southward, and the expected +storm at that point proved "a dry northeaster." Sometimes the +condensation, although sufficiently dense to influence and attract the +surface atmosphere, and create an easterly wind and scud, does not become +sufficiently dense to drop rain, and then, too, we have a dry northeaster, +which may melt away or increase to a storm after it has passed over us. _I +have never seen, except, perhaps, in a single instance, one of these +masses of scud, however dense, which had not a rain (stratus) cloud above +it, drop moisture enough to make the eaves run._ So you see it may be +true, and if you will examine carefully, you may satisfy yourself that it +is true, that the storms all move from a westerly point to the eastward, +notwithstanding the wind under them is blowing, and the scud under them +are running to the westward. + +There are many other methods by which the reader may determine this matter +himself. He may catch an opportunity for a view, when there is a break in +the stratus cloud above, and the sun or moon, no longer obscured by the +_storm cloud_, shines through the scud beneath. Then he may see they are +moving in different directions. _The upper cloud, if there be any of it +left, always to the eastward._ + +Again, we may see the storm approach from the westward, as it often does, +before the wind commences to blow, and the scud to run from the eastward; +particularly snow storms in winter, and the gentle showers and storms of +spring. + +Again, thunder storms, we know, come from the westward, and apparently +against an east wind. It is sometimes said they approach from the east, +but it is a mistake. During thirty years attentive observation in +different localities, I have never seen an instance. They sometimes _form_ +over us, or just east of us, or one may form at the east and another at +the west, and as they _spread out in forming_, one may seem to be coming +from the east, or there may be an easterly current, with dense flocculent +scud at the under surface of the shower cloud running westward, but they +finally pass off to the eastward, and never to the westward. It is +possible that a _patch of scud_ may become sufficiently _dense_ and +_electrified_ to make a _shower_, but I have never observed one. Such an +_apparent_ instance may be found recorded in "Sillman's Journal," vol. +xxxix. page 57. I have seen the scud assume a distinct cumulus form, but +never to become sufficiently dense to make a thunder shower. + +Thunder and lightning sometimes attend portions of regular storms in +spring and autumn, but the thunder is always heard first in the west, and +last in the east. + +Again, there are admitted facts with which you are conversant, which prove +this proposition. When it has been raining all day, and just at night the +storm has nearly all passed over to the eastward, and the sun shines under +the western edge of it, and "_sets clear_," as it is termed--you say that +"_it will be clear the next day_." Why? Because the storm will not pass to +the westward, covering the sun and continuing, how strong soever the wind +may be from the east; and because it is passing, and will continue to pass +off to the eastward, leaving the sky clear. _The easterly wind will stop +as soon as the storm clouds have passed, and it will fall calm, or the +wind will "come out" from the westward._ + +So, too, when the clouds are dark in the west in the morning, and the sun +rises clear, but "_goes into a cloud_," as it is expressed, you say that +it will rain. And if the clouds are dense this generally proves true; +because there is a storm or shower approaching from the west, and passing +over to the east, the western edge of whose advance condensation has met +the sun in his coming, and obscured him from your vision. + +When, too, it has been storming, and lights up in the N. W. you say it +will clear off; the N. W. wind will blow all the clouds away. It is, +indeed, generally true that when it so lights up it is about to clear off; +although it sometimes shuts down again, in consequence of the approach of +another storm from the westward, following closely behind the one which is +passing off. It is a great mistake, however, to suppose the N. W. wind +blows away the clouds. Watch the smooth stratus rain cloud at its lower +edge, where the clear sky is seen, and you will see that it is moving on +steadily to the N. E., in obedience to the laws of its current, and will +do so, even when its retreating edge has passed up to the zenith, and down +to the S. E. + +The storm uncovers us from the N. W. by the contraction of its width, _or_ +because it has a _southern lateral extension_ and _dissolution_, and not +by being blown away by the N. W. wind; although that wind, by its peculiar +fair-weather clouds, may be, perhaps, observed beneath, ready to follow +its retreating edge. + +Again, when it has been clear all day, and the sun sets in a bank of +cloud, you say--"_it will rain to-morrow, the sun did not set clear_," and +unless that bank is a thunder cloud, merely, which will pass over or by +you, with or without rain, before morning, it is generally true that it +will. The bank will prove the eastern edge of an approaching storm. + +From these generally admitted and understood facts, you may know that +storms pass from the west to the east. + +This proposition is also proved by all the investigations of storms, which +have taken place since the settlement of this country. Storms of great +severity attract particular attention, and are said to "back up" against +the wind, because they are observed to commence storming first at the +westward, although the wind is from the eastward. Doubtless you recollect +many such instances recorded in the newspapers. No season occurs without +such notices. + +Many storms have been investigated by Mr. Redfield, for the purpose of +sustaining his theory. Many others by Professor Espy, to sustain his. One +by Professor Loomis, with great research and ability--and some by others, +accounts of all which have been published; and every one yet investigated, +north of the parallel of 30°, has been shown to pass from a westerly to an +easterly point. + +So, too, we may know it from analogy. The laws of nature are uniform. +There is a great end to be accomplished, _viz._: the distribution of forty +inches of water, at regular intervals, over a large extent of country. The +rivers are to return, and the clouds are to drop fatness, and seed time +and harvest are not to cease. It is to be done and is done, by means of +storms and showers, and pursuant to general laws, as immutable as the +result. Most of these storms and showers, it has been found, and may be +observed, move from the westward to the eastward. Then we may know, from +analogy, that they do so in obedience to a general, uniform law; and so I +might say with confidence, if our inquiry stopped here, it will ever be +found by those who may hereafter examine them. + +But, 2d. There is a current in the atmosphere, all over the continent +north of the N. E. trades, but in great volume over the United States, +east of the meridian of 105° W. from Greenwich--varying in different +seasons, and upon different parallels, and flowing near the earth, when no +surface wind interposes between them. In the vicinity of New York, the +usual course of this current is from about W. S. W. to E. N. E. In the +western and south-western portion of the United States, it is, doubtless, +more southerly--varying somewhat according to the season--and in other +sections varies in obedience to the general law of its origin, and +progress. + +I have observed its course in many places, between the parallels of 38° +and 44° N. _This current comes from the South Atlantic Ocean._ It is our +portion of the aerial current, which flows every where from the tropics +toward the poles, to which I have already alluded in connection with the +distribution of heat. _It brings to us the twenty inches of rain which we +lose by the rivers, and by the westerly winds, which carry off a portion +of the local moisture of evaporation, and its action precipitates the +remaining portion of that moisture. It spreads out over the face of our +country, with considerable, but not entire uniformity. All our great +storms originate in it, and all our showers originate in or are induced +and controlled by it._ + +_From the varied action, inherent or induced, of this current, most of our +meteorological phenomena, whether of wet or dry, or cold or warm weather, +result_; and a thorough knowledge of its origin, cause, and the reciprocal +action between it and the earth, is essential to a knowledge of the +"_Philosophy of the Weather_." + +Let us then go down to the "chambers of the south," to the inter-tropical +regions, of which we have said something in connection with a notice of +Southern Mexico, and see where, and how this great aerial current +originates. + + + + +CHAPTER IV. + + +Between the parallels of 35° north latitude, and 35° south +latitude--changing its location within this limit at different seasons of +the year--encircling the earth, and covering about one-half of its +area--we find the trade-wind region. In this region are the simple and +uniform arrangements, which extend every where, and produce all the +atmospheric phenomena. In the center of it we find that movable belt of +continual or daily rains, and comparative calms, particularly _near its +center_, about four hundred and fifty miles in width upon the Atlantic, +and over Africa, and the eastern portions of the Pacific, and something +more over South America and the West Indies, the western portion of the +Pacific and the Indian Ocean, to which we have already alluded. This belt +of rains and calms follows the trades and sun, in their transit north and +south, from one tropic to the other--its width and extension depending +upon the volume of trade-winds existing on the sides of it. Its southern +edge, when the sun is at the southern solstice, extends to 7° south in the +Atlantic, to 10° south in the Indian Ocean, and still further, probably, +over South America: on this point I do not pretend to be accurate, for +accuracy is not essential. When the sun is at the northern solstice the +southern edge is carried up as far as 12° north, over the Atlantic, and +still further over the northern portions of South America, the West +Indies, and Mexico. It travels, therefore, from south to north, over from +twenty to forty degrees of latitude. The presence of this belt of rains +over any given portion of the inter-tropics, gives that portion its rainy +season, and its absence, as it moves to the north, or the south, gives the +portion from which it has moved, its dry season. It passes in its transit +twice each year over some portions of the country, Bogota, for instance, +and two corresponding rainy and dry seasons result. Its presence, and +character, and movements, are as fixed and regular, over from twenty-five +to forty degrees of the earth's surface, _and all around it_, as the +presence and movements of the sun over the same area. + +At the northern edge of this movable belt of rain, and extending in some +places, particularly in the Pacific Ocean, north about 20°, or about one +thousand four hundred miles, and in other places a less distance, the N. +E. trade winds prevail, blowing toward and into it from N. N. E., N. E., +and E. N. E., averaging about N. E. At the south line of this belt of +rains, extending south from twenty-five to thirty degrees, or from sixteen +hundred to two thousand miles, the S. E. trades blow toward and into it, +from the S. E., S. S. E., or E. S. E., averaging about S. E. Of course the +northern limit of the N. E. trades travels north and south with the belt +of rain, toward which it blows; and so the southern limit of the S. E. +trades travel in like manner with the rainy belt, or rather, to speak with +entire accuracy, the belt of rain moves with the trades, and the trades +follow the verticality of the sun. The following diagrams exhibit +approximately, and with sufficient accuracy for illustration, the +situations of the rainy belt and the trades, when at their northern and +southern limit, as well as the manner in which it must give certain +localities two rainy seasons each year, in its transit north and south. + +At the northern and southern limits of the trade-winds, and extending from +them to the poles, are found the variable winds and irregular +extra-tropical rains, all over the earth, which are shown by the shading +on the maps. This line of extra-tropical rains descends to the south, +following the retreating trades as they descend in our winter, and recedes +north before the trades when they return in spring and summer, so that at +the outer limit of the trades respectively, toward the poles, the line of +extra-tropical rains will be found, receding or following that limit, as +the trades pass up and down with the sun. From the north pole to the +northern limit of the N. E. trade-winds, wherever found, whether at 38° +north latitude, as in some places in summer when the sun is at the tropic +of Cancer; or whether at 20° to 30° north latitude, as in our winter, when +the sun is at the tropic of Capricorn; the extra-tropical rains prevail. A +state of things precisely similar exists between the south pole and the +southern limit of the S. E. trades. Between this northern limit of the +N. E. trades and the northern line of the inter-tropical belt of +rains, wherever situated (with two exceptions, to which we have alluded +and shall allude again), there is, for the time being, a dry season; and a +like dry season between the southern line of the belt of rains and the +southern limit of the S. E. trades. We have, therefore, extending around +the earth, a belt of daily tropical rains, near the center,--two belts of +drought which are mainly trade-wind surfaces, one on each side of the +central rainy belt,--extending to the outward limits of the trades and the +line of extra-tropical rains; and these rainy and dry belts, moving up and +down after the sun, a distance of from twenty to forty degrees of +latitude, each year. + + +[Illustration: Fig. 10. IN SUMMER.] + +[Illustration: Fig. 11. IN WINTER.] + + +Such are the _main_ phenomena, _at the surface_, in the trade-wind region. +Ascending a step higher in the atmosphere, we find, above the +surface-trades, a counter-trade, running, not in the opposite direction, +but at right angles, or nearly so. The counter-trade which issues from the +northern side of the rainy belt, running to the N. W. or W. N. W., and the +counter trade which issues from the southern side, running to the S. W. or +W. S. W., varying, as the trades do in direction in different localities. +These counter-trades are continuations of the surface trades, which, +ascending in their course, have threaded their way through the opposite +trade in the rainy belt, and are continuing on at the same angle, and in +the same direction at which they blew upon the surface, and in obedience +to the same law. This is apparent from several considerations. + +1st. They issue at the same angle, and over the top of the surface trades. +In the West Indies and elsewhere, this has been ascertained and proved by +the course of the storms, and the rotation of their surface winds, and +observation. + +2d. We can not suppose the N. E. trade to be reflected, and turn back over +itself at a right angle. That would be impossible, even if there were a +wall of solid material there for it to blow against. Air is a peculiar +fluid, and it stratifies with astonishing ease. He who supposes that a +current of air put in motion can be turned aside by another current, or by +the atmosphere at rest, or can be made to mingle, is mistaken. It will +stratify, and force itself onward through the adjacent and opposing +atmosphere, and in a right line. I have observed some remarkable instances +of this character. + +3d. The cause which operates to produce the surface trades, still operates +upon the current to carry it over into the other hemisphere; a +counter-trade, as we shall see. It is impossible, therefore, to believe +that the surface-trades as they arrive at the belt of rains and calms, +turn at a right angle, or at any angle, and return: and impossible to +doubt that they pass through each other in this belt, and out at the +opposite side, as upper currents, at the same angle at which they entered. +Of course the N. E. trade of the Atlantic becomes the N. E. counter-trade +of South America, carrying their storms in a S. W. direction, and the S. +E. trade of the Atlantic the S. E. counter-trade of the West Indies, +carrying all their storms in a N. W. direction; and what is true of them +is true of the trade winds _every where, all over the globe, over the land +and over the sea_. + +Doubtless here some one will say, our upper current is a S. W. current. +True, the S. E. trade which enters the belt of rains, and issues out on +the north, a S. E. upper current or counter-trade, keeps that course until +it arrives at the northern limit of the surface trade, when, in _obedience +to another law_, which we shall notice, it gradually _decends near the +surface, curves to the eastward_, and becomes _the S. W. current which +passes over us_. And so we have the S. E. trade-wind of the South +Atlantic, with its moisture, warmth, electricity, and polarity, over, and +perhaps sometimes around us, dropping the electric rain which makes glad +our fields; giving us, when not prevented by other conditions, the balmy +air of spring, the Indian summer of autumn, and the mild mitigating +changes of winter; and thus, _our rivers, which run into the sea, return +to us again_. + +But let us go back to the trade-wind region--the region of regularity and +uniformity--and examine somewhat more attentively its features, that we +may more fully understand the character of this counter-trade. + +Here are 60° at least of the 180° of the earth's surface, and at its +largest diameter, covered in the course of the year, and of their travels, +by the trade-winds at the surface, the counter-trades above, and the belt +of rains and comparative calms, formed by the action of the opposite +trades, as they thread their way through each other, to assume the +relation of counter-trades. Truly the magnitude, simplicity, and +regularity of this machinery are most wonderful. + +There are, however, some _apparent_ anomalies which deserve attention. +Here are most distinctly marked the _rainy_ and _dry seasons_, existing +side by side. Here are the _rainless portions_ of the earth, already but +briefly alluded to; here the _monsoons_, and another peculiarity, _viz._: +the _gathering of the counter-trades_ upon the western sides of the two +great oceans, into two _aerial currents of greater volume_, _analogous_ +somewhat to the two _gulf streams_ of those oceans. Let us examine these +anomalies. + +The rainy and dry seasons depend, as we have seen, upon the transit north +and south of the rainy belt, or belt of comparative calms. Wherever this +belt may happen on any given day to be situated, each side of it the +trades prevail, it is dry, the earth is parched, and vegetation withers. +These changes are graphically described by Humboldt in his "Views of +Nature," as they occur on the northern portions of South America, as +follows: "When, beneath the vertical rays of the bright and cloudless sun +of the tropics, the parched sward crumbles into dust, then the indurated +soil cracks and bursts, as if rent asunder by some mighty earthquake. The +hot and dusty earth forms a cloudy vail, which shrouds the heavens from +view, and increases the stifling oppression of the atmosphere; while the +east wind (_i. e._ trade-wind), when it blows over the long heated soil, +instead of cooling, adds to the burning glow. + +"Gradually, too, the pools of water, which had been protected from +evaporation by the now seared foliage of the fan-palm, disappear. As in +the icy north animals become torpid from cold, so here the crocodile and +the boa-constrictor lie wrapped in unbroken sleep, deeply buried in the +dried soil. Every where the drought announces death, yet every where the +thirsty wanderer is deluded by the phantom of a moving, undulating, watery +surface, created by the deceptive play of the reflected rays of light (the +mirage). A narrow stratum separates the ground from the distant +palm-trees, which seem to hover aloft, owing to the contact of currents of +air having different degrees of heat, and therefore of density. Shrouded +in dark clouds of dust, and tortured by hunger and burning thirst, oxen +and horses scour the plain, the one belowing dismally, the other with +outstretched necks snuffing the wind, in the endeavor to detect, by the +moisture in the air, the vicinity of some pool of water not yet wholly +evaporated. + +"Even if the burning heat of day be succeeded by the cool freshness of the +night, here always of equal length, the wearied ox and horse enjoy no +repose. Huge bats now attack the animals during sleep, and vampyre-like +suck their blood; or, fastening on their backs, raise festering wounds, in +which mosquitos, hippobosces, and a host of other stinging insects, burrow +and nestle. Such is the miserable existence of these poor animals, when +the heat of the sun has absorbed the waters from the surface of the +earth. + +"When, after a long drought, the genial season of rain arrives, the scene +suddenly changes. The deep azure of the hitherto cloudless sky assumes a +lighter hue. Scarcely can the dark space in the constellation of the +Southern Cross be distinguished at night. The mild phosphorescence of the +Magellanic clouds fades away. Even the vertical stars of the +constellations Aquila and Ophiuchus, shine with a flickering and less +planetary light. Like some distant mountain, a single cloud is seen rising +perpendicularly on the southern horizon. Misty vapors collect and +gradually overspread the heavens, while distant thunder proclaims the +approach of the vivifying rain. Scarcely is the surface of the earth +moistened, before the teeming steppe becomes covered with Killingiæ, with +the many-panicled Paspalum, and a variety of grasses. Excited by the power +of light, the herbaceous Mimosa unfolds its dormant, drooping leaves, +hailing, as it were, the rising sun in chorus with the matin song of the +birds, and the opening flowers of aquatics. Horses and oxen, buoyant with +life and enjoyment, roam over and crop the plains. The luxuriant grass +hides the beautiful and spotted jaguar, who, lurking in safe concealment, +and carefully measuring the extent of the leap, darts, like the Asiatic +tiger, with a cat-like bound on his passing prey." + +Such is Humboldt's description of the dry season on the Orinoco, and the +return of the belt of rains from the south. + +Again, within this trade-wind region are the _rainless countries_. These +are portions of the earth which the equatorial rainy belt does not ascend +far enough north in summer to cover, nor does the southern edge of the +extra-tropical regular rains descend, in winter, far enough south to cover +them, and where, of course, rain seldom, if ever, falls. Such are the +central parts of the Desert of Sahara, Egypt, Arabia, portions of +Affghanistan, Beloochistan, and the western parts of Hindoostan, to the +north of the inter-tropical belt, and a similar state of things exists +south of the equator in parts of South America, Africa, and New Holland, +although upon a comparatively small surface. + +Again, another anomaly is the gathering of the trade winds into greater +volumes, on the westerly side of the great oceans, and the consequent +carrying of the equatorial rainy belt up to the region of extra-tropical +rains, on the eastern side of the great continents of Asia and North +America, and the peculiar liability of these aerial gulfs to hurricanes +and typhoons. Such an aerial gulf gathers over the Caribbean Sea, and the +West Indies. Passing across the Gulf of Mexico, it enters over Texas, and +Louisiana, and the other southern states; its western edge passing north +in autumn and winter, on the eastern side of the highlands of Western +Texas, New Mexico, and the Great Desert; curving, as all counter-trades +do, to the eastward as soon as it passes the limit of the N. E. trades, +and spreading out over our favored country, leaving the evidence of its +pathway in the greater quantities of rain, which fall annually upon its +surface. This gathering deprives a portion of the Atlantic, north of the +tropics, of its share of the counter trade, and there, as every where, +where the volume of counter-trade is small, storms and gales are +infrequent, and of less force, and comparative calms prevail. That portion +of the Atlantic has long been known as "the horse latitudes," a name given +to it by our Yankee sailors, because, there, in former times, the +old-fashioned, low-decked, flat-bottomed, horse-carrying craft of New +England, bound for the West Indies, often floundered about in the calms +and baffling winds, until their animals perished for want of water, and +were thrown overboard. Lieutenant Maury, in his most praiseworthy and +exceedingly useful investigation of "The Winds and Currents of the Ocean," +has defined the situation of these calms and baffling winds at different +seasons--for they move up and down, of course, with the motion of the +whole machinery--and enabled navigators to avoid them, by running _east_ +before they attempt to make _southing_; and very materially shortened the +voyages to the equator. + +A like gathering, in volume, of the S. E. trade, on the western side of +the Pacific, enters over Asia, and covers China and Malaysia, extending, +in its western course, nearly as far as the western edge of Hindoostan. In +this concentrated volume of counter-trade, and owing to its concentrated +action, form and float the typhoons of the China Sea, and of the Bay of +Bengal; and to this anomalous aerial gulf stream, the S. E. portions of +Asia, from the western desert of Hindoostan, to the eastern portion of +China, north of the rainy belt, owe their great supply of moisture and +fertility, and their peculiar climate. The western line of this volume of +counter-trade is marked by the eastern portion of the rainless region of +Beloochistan, and the north-western deserts of India, as the western edge +of our concentrated volume of counter-trade, is marked by the arid plains +of northern Mexico, western Texas, and New Mexico. On the south of the +equatorial rainy belt, there is no corresponding aerial gulf of equal +volume, as there is no corresponding gulf stream of equal magnitude. On +the western side of the Indian Ocean we find a gathering of the N. E. +trades from the Bay of Bengal and the Indian Ocean, in which form and +travel the hurricanes which prevail--traveling to the southward and +westward--about the Isle of France or Mauritius; and the lagullus oceanic +current, which runs down to the S. W. toward the Cape of Good Hope. But +the extension of South America to the eastward, under, or just south of +the N. E. trades, does not permit the formation of such a concentrated +volume on the western side of the Atlantic, nor is the strength or +regularity of the N. E. trades, on that ocean, equal to those of the S. E. + +Nor is the magnetic intensity on the eastern and middle portions of the +Pacific, sufficient to produce such a concentration, in large volume, +there. The trades over that ocean, therefore, curve without concentration, +except a partial one, over the western groups of Polynesia, which the +Asiatic line of magnetic intensity approaches and where hurricanes are +sometimes found, until we arrive near the eastern line of magnetic +intensity, on the eastern side of Asia. We shall, hereafter, have occasion +to follow the anomalous concentrated volumes of the S. E. counter-trade, +of the northern tropic, on the western side of the great oceans, in +explanation of some of the phenomena which we find north of the trade-wind +region. Suffice it here to add, that if it were not for the concentration +of these counter-trades, on the western side of the great oceans, the +rainless region between the parallels of 20° and 30° would encircle the +earth; and China and the Eastern United States would have a distinctly +marked rainy and dry season, as have California, the Barbary States, +Syria, Persia, and other countries which lie north of the rainless region, +within the summer range of the N. E. trades, but also within the winter +descending range of the belt of extra-tropical rains. + +Another anomaly which we find in the trade-wind region, is the monsoon. +There are several of them, but they are found, in the greatest strength +and regularity, in the Indian Ocean. Another, defined by the +investigations of Maury, is found on the west coast of Africa, extending +out over the Atlantic. Another prevails on the western coast of South and +Central America. The etesian winds of the Mediterranean are but the N. E. +trades, whose northern limit is carried up in summer, by the transit of +the connected machinery, to the north, over that sea. The N. E. and S. E. +monsoons, so called, of the Indian Ocean, are but the regular trades, +blowing when the belt of rains is absent, as they do all over the globe. +The N. W. monsoon, south of the equator, in the vicinity of New Holland; +the S. W. monsoon which blows from the Arabian Sea, in upon Hindoostan; +the S. W. monsoon of the Atlantic, south of the Cape De Verde Islands; and +the variable west monsoon winds of the west coast of Southern and Central +America, and Southern Mexico (known under several different names, but +chiefly by that of Tapayaguas), are all that deserve attention as such. + +At first sight they appear to be anomalies, but the facts declare their +character with perfect certainty. First, they are not continuous, like the +trades, but _prevailing_ winds, and are _storm winds_; _they always blow +toward a region_, _or portion of the ocean_, _covered at the time by +clouds and falling weather_. + +Second, they do not blow upon, or toward, heated surfaces of land or +water--_i. e._, toward the dry and parched surfaces, where the dry season +prevails, or from adjoining cold waters on to warm surfaces, but toward +the land or water _situated under the rainy belt_. They are therefore +incident storm winds, (as our easterly winds are incident storm winds) of +the rain clouds of the tropics. They blow in upon the land, under the belt +of rains, while that belt with its daily cloud, and inducing electric +action, is over it, and follow that belt in its transit north and south. +They blow from the warm south polar current of the Atlantic, which flows +N. W. from the coast of Africa, toward the inshore north polar current, +which is there flowing south, but under the belt of rains. In the Indian +Ocean they blow from the center of that ocean, and the Arabian Sea, toward +the belt which hangs over Hindoostan, from the S. W.; and when the rainy +belt travels south they still blow toward, and under it, from the Indian +Ocean, but of course from the N. W. The heated character of the waters of +the Indian Ocean and Arabian Sea, which receive no polar currents, but +heated waters from the Persian Gulf, and from rivers which flow into the +Bay of Bengal over the heated plains of a tropical country, explain this. +So, too, the monsoon of the Atlantic Ocean, does not blow north of the +Cape De Verde Islands,--where the heated surface of Sahara, burning with +the rays of a vertical sun, has a temperature sometimes ranging from one +hundred and forty to one hundred and sixty degrees--but remains under the +rainy belt, drawn from the heated waters which flow up from the South +Atlantic, and travels north as the rainy belt travels north in summer, and +south to the Gulf of Guinea, as that travels south in winter. The same is +true of the Pacific monsoon, the Tapayaguas, the least marked of all, +which blows in during the rainy season upon the west coast of Southern +Mexico, and of Southern and Central America. They are all incident rain or +storm winds, blowing in upon the land, or on to a colder surface of +different polarity, _during the rainy season_; and if it were possible to +catch one of our north-easters, in its passage over our country to the +eastward, and anchor it to the Alleghanies, "paying out" so to have it +reach in part over the Atlantic, and keep it there in operation six +months, we should have a continual easterly wind under it; a _monsoon_ +more strongly marked than the monsoons of the Indian, or Atlantic Oceans. +_The received theory in relation to them is a fallacy._ + +Recapitulating, then, all the phenomena, we have,--_Surface-trades_, +blowing toward the center, passing through each other, and continuing on +as upper or counter-trades; a _belt of rains_, with calms near the center, +formed by the trades where they meet and pass through each other, which +travels with them north and south following the sun; _two belts of +drought_, following the belt of rains and the trades, and followed by the +_extra_-tropical line of rains, as it travels with the trades and the +rainy belt, leaving a part of the earth which the equatorial rainy belt +does not travel far enough north, nor the extra-tropical line of rains far +enough south to cover, and which is consequently a _rainless region_; _the +monsoons_, which are but incidents of the rainy belt, and the _gathered +volumes_ of counter-trade, on the west of the two great oceans, which +usurp the place of the N. E. trades, carrying the rainy belt up to the +region of extra-tropical rain, and preventing the rainless region from +encircling the earth. + +Upon _what cause_ do these great central phenomena, so vast, so regular, +so wonderful, depend? What is the _motive power_ of this connected +atmospheric machinery, whose action and influence extend over the entire +globe? + +"_Heat, heat_," say the text books, the Professors, the votaries of +meteorology. "All these phenomena are owing to the heat of the sun. It +heats the ocean and the earth--the air is thereby heated and rises, the +cold air rushes in from below, then the ascended current rolls off each +way at the top toward the pole, acquiring a westerly motion from the +rotation of the earth, slipping away from under it, and a different, +_viz._: an easterly motion, after reaching the latitude of 30°, from the +_same rotation_; and all the winds and disturbances of the atmosphere are +produced in the same way. They are produced by the action of heated +surfaces upon the adjacent atmosphere." + +This is the great theory of meteorologists, by which they attempt to +account for the various atmospherical disturbances, of both tropical and +extra-tropical regions. + +The whole theory is a fallacy--it will not stand the test of a careful +examination. The bases of the theory, which are assumed to be facts, are +not so. The agent has not the power claimed for it. A heated surface, +alone, never caused any considerable ascending current, or if it did, +never produced a mile of wind. I repeat it, the theory and all incidental +ones--the thousand explanatory and modifying theories, and +hypotheses--_the whole system_--is without foundation in fact, and will +not bear a critical examination. + +Let us see if this language is stronger than the facts will warrant. + +The theory assumes that both the land and water, under this central belt, +where the air is supposed to be rising are _materially hotter_ than the +land and ocean are on _either side of it_. Now, how much hotter are the +air and the land under the belt of rains and calms, upon Hindoostan, or +Africa, or South America, where the former is supposed to be acquiring +heat and expansion so rapidly, and to be ascending, than under, and in the +dry belts on either side? None; it is cooler by the thermometer--_much +cooler_. + +The central belt of rains in midsummer over Africa, extends up as far as +17° north latitude, and perhaps further. North of this line over the whole +surface of the desert, the Barbary States, a part of the Mediterranean, +and some portion of Italy, the dry season extends, and from the entire +surface the N. E. trade blow into the central belt.[1] Over the desert +they all pass. Now this desert is a sea of sand, under a vertical sun, +intensely heated, blistering the skin with which it comes in contact, and +often acquiring a temperature of 150° to 160° of Fahrenheit. Under the +central belt of rains neither the earth nor air exceed the temperature of +84°. And yet the hot air of the desert does not ascend, but blows into +this cooler central belt; and when it is felt as it blows off the western +coast by the mariner, or even in Guinea, when the belt of rains has gone +south in winter, as it often is as the _harmattan_, it is suffocating and +intolerable. There, then, not only is it untrue, that the land and the air +over it under the rainy belt are hotter, but it is true that intensely +heated air blows horizontally from the Desert of Sahara. Nay, as it will +appear in the sequel, this hottest of all surfaces not only can not have a +vortex, but it can not induce a monsoon, and scarcely a sea breeze. The +same is true in a great degree of the surface, and the air over it, on +either side of the supposed vortex of the rainy belt upon South America. +See the description of Humboldt, already given, where the thermometer +stood as high as 115° of Fahrenheit in the shade, while the N. E. winds, +the regular trades, were blowing over the land. And it is equally true of +Arabia, and indeed of every portion of the earth. There is not a spot upon +the globe where the land and the air are cooler _by the side_ of the +central belt of rains, than _under it_. _And the opposite is true every +where upon the land._ + +How much hotter is the ocean and air under this supposed vortex? But +little hotter than they are on the side where the sun is not vertical, +_and none on the other_. Let us be a little more particular. The +temperature of the Atlantic under the belt of rains in our winter, and on +the south of the belt at the latitude of 3° south, and down to 9° or more +south, is 82°. The air may range a degree, or possibly two, higher than +the water at either point. On the north this difference is from nothing at +the meeting of the trades and belt of rains, to about 4° at their northern +limit. This is too _trifling_ to be worth one moment's consideration. It +is less, far less than the difference between the water and air of the +Gulf Stream which runs along our coast, and the adjoining waters and air +over them. While on the south side of the belt of rains the _difference is +actually against the theory_--and the same state of things is reversed in +summer, when the sun is vertical at the north. + +From the log of an intelligent shipmaster, found in the wind and current +charts of Lieutenant Maury, I abridge the following, which will illustrate +this. Captain Young in February, found the N. E. trades at about 17° north +latitude, with the water at 75° and air at 76°, trade-wind N. E. + + At 12° 16' the water was 75° the air 76° wind N. E. + Feb. 22d. 9° 49' " 76-1/2° " 77° " N. E. + " 23d. 7° 13' " 78° " 78° " N. E. + " 24th. no obs. " 79-1/2° " 79° " N. E., + E. S. E. rain. + " 25th. 3° 10' " 81° " 83° " E. S. E. rain. + " 26th. no obs. " 82° " 82° " S. E. to + E. S. E. hazy, + rain & sqs. + " 27th. 2° 24' " 82° " 82° " calm, + with rain. + " 28th. no obs. " 82° " 82° " calm rain. + March 1st. 0° 29' " 82° " 82° " E. S. E. + sqs. rain. + " 2d. 1° 27' S. L. " 82° " 82° " S. E. sqs. + rain. + " 3d. 2° 44' " 82° " 83° " S. E. & + S. S. E. + weather + settled. + " 4th. 4° 17' " 82° " 83° " S. S. E. & + S. E. fair + weather. + " 5th. 6° 08' " 82° " 84° " S. E. fair + wthr. + " 6th. 8° 08' " 82° " 84° " S. E. & + E. S. E. fair + weather. + +Here the air was seven degrees colder at the extreme limit of the N. E. +trades than in the _center_ of the belt of rains, as it is, usually, in +mid-winter, but not in summer. On the other hand, _after he left the +region of calms and rains_, where the water and air stood with almost +entire uniformity at 82°, on the 3d of March, and for three days +thereafter, during which he was in the S. E. trades with fair weather, +the water was the same as under the supposed vortex, _viz._, 82°, _and the +air rose to 83° and 84°_! _This is demonstration._ + +I also take from a letter of Lieutenant Walsh to Lieutenant Maury, +relative to the cruise of the "Taney" the following, showing the warmth of +the Gulf Stream compared with the adjacent ocean. + + "We first crossed the Gulf Stream on the 31st of October; we struck + it in latitude 37° 22', longitude 71° 26' as indicated by the + temperature of the water, which was as follows: + + 8 A.M. water at surface 66° + 9 " " " 73° + 10 " " " 76° + 11 " " " 77° + + 77° was the highest temperature found in crossing at this time. + + Re-crossing it in May, in latitude 35° 30', longitude 72° 35', he + found the water as follows: + + 8 A.M. water at surface 71° 8' + 9 " " " 73° + 10 " " " 75° 5' + 11 " " " 78° 5' + 12 M. " " 78° 5' + + 79° being the highest temperature found." + +The average difference between the temperature of the water of the Gulf +Stream and the adjoining ocean, at the line of division, is about ten +degrees, increasing to more than twenty on approaching the coast, and +within one hundred miles--a far greater difference than is ever found on +the winter side of the inter-tropical rainy belt. + +It is not only not so, then, that the surface of the ocean is materially +warmer under the belt of rains than the adjoining surface under the +trades, especially on the summer side, but if it were so, the trades would +not be created thereby, any more than upon the Gulf Stream. And the +opposite is true of the land where the line of calms, and rains, and +drought meet, all around the globe. The fact assumed is therefore untrue. +The hottest surfaces, even at the rainless portion, where there is no +vortex, no storm, and no wind but the continual uniform N. E. horizontal +trade-wind, _never_ created, by reason of the heat alone, a mile of wind, +a storm or shower. + +But, again, the belt of calms, where the air is supposed to rise and +create a suction which draws the trades on either side a distance of from +one thousand to two thousand miles, an average of three thousand miles in +all, at least, is not itself, on an average, over five hundred miles in +breadth from north to south. What a wonder of meteorology is here! + +With a breadth of five hundred miles, the rising of the atmosphere is +supposed to be so rapid and of such immense volume that it draws the +surface atmosphere, one thousand to fifteen hundred miles on one side and +two thousand on the other, with a uniform steady velocity of twenty miles +per hour. Is this vast suction found by the unlucky mariner who may be +drawn within the vortex? _Not at all._ He finds no rapid suction there, +but _horizontal currents_, not steady, indeed, like the trades, and +sometimes calms _at the center_, but still the _currents are there_, and, +_except near the center, there as squalls, showers, and baffling winds +and as monsoons_. + +Again, is there at the mouth of this vortex, or as you approach it, an +increased rapidity in the trade corresponding to the magnitude of its +influence? Does the trade become a hurricane as it approaches the spot +where it is to supply the place of that which has suddenly "expanded by +heat, and been forced to rise, boil over, and run off at the top in turn?" +Not at all. It blows gently, even up to the very line of the rainy belt, +and becomes squally and baffling, falls gradually calm near the center, or +changes to a monsoon. + +But, again, the belt of rains is so far from being a belt of calms +strictly, that its monsoons in the Indian, Atlantic, and Pacific Oceans, +at times, extend hundreds of miles out over the ocean. That of the +Atlantic, triangular, with its base resting on Africa, according to +Lieutenant Maury, extends sometimes almost to the coast of South America, +a distance of one thousand miles, and thus under the supposed ascending +vortex. Where is the great uprising suction during the prevalence of this +extensive surface horizontal monsoon beneath it? Manifestly it does not +exist. Nay, that monsoon is blowing from the warm current which sets up +from the Cape of Good Hope toward the Caribbean Sea, and over the cold +north polar current, which runs down between the continent and the Cape de +Verdes. Equally untrue is the presumption that the air rises over heated +portions of the earth elsewhere, and by reason of such heating. +_Perpendicular currents of the atmosphere are rarely seen, never +extensive, or attaining any considerable altitude._ I have watched for +them thirty years. I have seen currents of air ascend, with their moisture +condensing as they ascended, and unite with the under surface of a highly +electrified cloud--the advance condensation of a thunder shower--but that +cloud was moving horizontally at a distance of from one to two thousand +feet above the surface of the earth, and did not rise. I have seen patches +of scud rising from the surface during the intervals of a showery and +highly electrified storm, toward, and uniting with, the clouds above, when +very low, as I have seen them approach and unite horizontally; and +doubtless there is a tendency upwards of the wind, created and attracted +by the summer shower, as may be seen in the ascending dust before the +rain, but I have never been able to detect an ascending current, except as +induced and attracted by a cloud above moving horizontally, in the hottest +day or dryest time. None of the clouds of our climate, even when the earth +is heated and parched by a two months' unbroken drought, can be detected +rising above the strata in which they form. I have watched the cumuli at +such periods when they filled the air, and can assert that they never +rise. The atmosphere moves, invariably, in horizontal strata, and the +whole theory of ascending currents is fallacious. + +But let us look still further at the tropical currents. The true harmattan +of north-western Africa (for the term is sometimes misapplied), hot and +blistering, generated upon the sand of the desert--why does it blow from +Sahara horizontally, on or over cooler surfaces, following the belt of +rains as a N. E. trade? Why does it not ascend? The sirocco of north +Sahara, the kamsin or chamsin of eastern Sahara, and the simoon of Arabia, +which blow hot and suffocating from those deserts--why do they blow _from_ +heated surfaces and _horizontally over_ cooler ones? Why do they not +ascend? Arabia is surrounded on three sides by seas and gulfs, from which +evaporation is rapid. Her interior deserts are extensive and intensely +hot--why are they rainless? Why do they not have a _vortex_, a _monsoon_, +or even a _shower_? Because there is no such law or action as this theory +supposes. Those winds blow horizontally in obedience to other laws, and +under the control of other and more powerful agents. But further still, +what heating and ascending process is it that makes the variable winds +north of the tropics? that brings in the warm air and fog of the Gulf +Stream upon our _snow-clad coast_, in mid-winter, to increase the January +thaw? Nay, what heating process is it that disturbs the calms of the polar +regions with fresh breezes and gales, sometimes of the force of 6, when +the _sun does not shine_, the thermometer is from 20° to 40° below zero, +the _earth and sea one frozen surface_, and the hardy explorer dressed in +furs, barely lives in his cabin covered by an embankment of snow, and +heated by a stove? + +Gentlemen, meteorologists, it will not do. The theory is unsound; the +assumed facts do not exist. The whole universe has not an agent, organic +or inorganic, which can play such absurd and inconsistent pranks in the +face of its Creator, as your various and complicated theories assign to +caloric. + +Away with the theory and all its incidental and complicated and mystified +hypotheses, they rest like a pall upon the science;--away with the whole +system, and let us seek some agent whose _power_ and _adaptation_ +correspond with the _extent_, and _simplicity_, and _magnificence_ of the +phenomena, and, in some degree, with the _power_ and _wisdom of their +Author_. + + + + +CHAPTER V. + + +One, and the principal end attained by the power of the agent, is the +gathering of a volume of atmosphere from, or near, the _surface_ of the +land and sea, so as to ensure its possession of all the moisture of +evaporation which rises from the locality, and the highest degree of +temperature, and from a space ranging from one to two thousand miles in +width, in one hemisphere, and to carry it over into the other. Not over +the top, or upon the top, of the whole mass of atmosphere situated in the +opposite hemisphere--_out of reach of all influences from the earth_--but +through it, and curving gradually down near to, and within influential +distance of the surface of the earth, soon after it passes the outward +limit of its fellow trade; and to continue the current onward, leaving +portions of it and its heat and moisture on the way, but taking a +considerable volume up and around the magnetic poles--it being impossible +for the entire volume to be thus carried around the poles in consequence +of the diminished circumference of the earth. To this end it is obvious it +must possess _polarity_. + +Another end to be attained is to combine the moisture of evaporation with +the air, so that the cold atmosphere through which, or the earth over +which it passes, may not be _continually condensing its moisture_, and +thereby _enveloping the earth in a perpetual mist_; but so that it may +part with it at _intervals_, making _cloudy_ and _clear days_; and part +with it in _portions_, so that a _regular_ and _necessary supply_ may be +furnished to the _entire hemisphere_, even up to the geographical poles. +Is there such an agent? There is, precisely and perfectly adapted to the +ends to be attained, ever there and ever active, and that agent is +_magnetism_. + + +[Illustration: Fig. 12.] + + +The earth is a magnet. It has its magnetic poles, and they are distinct +from its geographical ones; and there are two in each hemisphere. They are +situated from 17° to 19° distant from the geographical poles; and ours is +not far from longitude 97° W. from Greenwich, and 71° north latitude. +Navigators have gone north and north-west of it, and found its situation +by the declination of the needle. From these poles, lines of magnetic +intensity extend to the opposite and corresponding pole of the other +hemisphere, and upon or near those lines the needle points north without +variation; and toward these lines of no variation the needle every where, +on either side declines. The foregoing diagram shows the situation of our +magnetic pole and line of no variation, the dip of the needle by the +arrows, and the magnetic equator. + +Recent discoveries have shown that the magnetic force is exerted in lines +and currents; that such currents, as physical lines of force, surround +magnets, and currents of electricity. Doubtless such lines of force exist +around the earth and the magnetic poles. There are also _longitudinal_ +lines of force existing and active, between the poles, and extending from +one side of the center to the other, occupying nearly one third of the +magnet. If you take a large needle thoroughly magnetized, place it upon +paper and drop filings of iron upon it, they will become arranged about it +in circular and perpendicular, and also in _longitudinal lines_, +conforming to the currents. + + +[Illustration: Fig. 13.] + + +This experiment is illustrated in all our books on natural philosophy. + +The foregoing diagram, copied from Olmstead's Philosophy, does not show as +accurately as Faraday's projection of the lines upon a globe-magnet the +comparative distance from the poles of the needle, at which the +longitudinal currents commence and terminate, and _where the filings will +not adhere_ to any considerable extent. The lines shown upon the needle +should bear the same proportion to its length as the trade-winds bear to +that of the earth, measured from pole to pole, and if the needle had a +globular form they would so appear. + +These lines are made by currents arising from one side of the magnetic +equator, and passing over to the other. Doubtless, just such currents +rise, and pass over upon the earth. + +Magnetic and electric currents carry the air with them. This is well +settled by experiment. _Oxygen_, too, is _magnetic_, and capable both of +receiving and retaining polarity and of combining with, or attracting and +retaining vapor, and of course the moisture of evaporation. Here then we +have a power existing, capable of producing the result--precisely, and +with evident wisdom adapted to its production--ever present and active; +and no other known agent can. + +Is it not then the agent? + +Let us look a little further. This result is affected by the action of the +sun: the trades with the central belts of rains travel north and south +after it; so does the sun affect the magnetic currents every where, even +the magnetic needle is daily affected by its action, as it increases the +intensity of the terrestrial magnetic currents, and hence its well +established diurnal oscillations. + +Again, along the eastern lines of the continents which skirt the great +oceans on the west, run the northerly and southerly lines of no variation, +and of greatest magnetic intensity. Here are the trade currents gathered +into a volume, which curve and carry unusual fertility to South-eastern +Asia, and North America, and in those great aerial gulf streams we find +the _intense_ electric action which produces the typhoons of the former, +and the hurricanes of the latter. It may still be said that these +conditions and phenomena of the trade-wind region, are not produced by +magnetism or magneto-electricity, _but the objector can point to no other +adequate power_. That it must be heat, electricity, or magnetism, must be +admitted. There is no other power known. Heat demonstrably can not produce +them. Magnetism or electricity therefore must, and they are doubtless +states or phases of the same power, producing in their different states or +phases the different results. And even heat--atmospheric temperature, is +often, if not always the result of their action. In the present state of +science, it is enough for me that the _magnetic longitudinal currents are +there_; that they are _lines of force_ and _adequate_; that _oxygen is +magnetic_, and therefore the atmosphere must be affected by them--that so +far as we can reason from analogy, they ought to produce the effect upon +the atmosphere which we find produced, and until further light is thrown +upon the subject I shall presume that they do. Every step we take +hereafter in this investigation will confirm the presumption. + +There is one peculiarity to be more particularly noticed before we leave +the trade-wind region, and we are now prepared to notice it. + +The belt of rains, formed by the currents of the two trades, threading +their way through each other--how are they produced? Why should the place +where the currents thus pass through each other be a place of almost daily +precipitation? There is, in fact, no ascension, except that which the +currents have in their line of ascent to attain the elevation which the +magnetic law of the current requires. + +The trades have passed over an evaporating surface and are charged with +moisture. This moisture they hold in magneto-electric combination. +_Evaporation_ does not depend upon _temperature_. Ice and snow evaporate +at all temperatures (Howard, vol. 1, p. 86). So the cold N. W. wind, full +of positive electricity, will lap up, as it were, the pools from the +earth, with astonishing quickness; and when this electricity is deranging +the action of the machinery and material of the manufacturer, he allays it +by a supply of moisture, with which the electricity can combine. Nor does +the air lose its moisture when below the freezing point. In all parts of +the atmosphere, as at the surface of the earth in winter, moisture is held +in large quantities in the coldest and severest weather; and it is not +till it moderates, and a perceptible _electric_ change takes place, that +it is precipitated as rain or snow. Doubtless there is an exposure of +considerable surfaces, of opposite currents, charged with opposite +polarity, and a constant depolarization where their surfaces meet. May +there not be a consequent dissolution of the electro-magnetic combination +between the air and moisture, or the excitation of that electric action +which attends or produces like rains every where? and hence the constant +precipitation. This is rendered probable, by the fact that precipitation, +at the meeting of the trades, takes place in level countries in the +day-time, between 10 A. M. and sunset, in showers, with thunder and +lightning, as with us in summer, although among the mountains the rain +sometimes falls in the night also. The precipitation in the heat of the +day is obviously induced by the action of the sun, although it is by no +means certain that the friction of the opposing surfaces does not assist +in the operation. + +I am well aware that the lines of magnetic force curve upward and carry +the trades with them, and that, therefore, precipitation by condensation +from the mere cold of the upper stratum of the atmosphere is possible. +But, there are three reasons why I do not believe such to be the fact. + +1st. Precipitation takes place in the day time mainly, and in sudden, +isolated, heavy showers and not in steady continuous rain. Nor is there +condensation or continual mist at other hours of the day. + +2d. They occur at a time of day when the sun is affecting the magnetic +currents most powerfully, _viz._, between ten o'clock A. M. and sunset, +and mainly at the time of greatest heat. + +3d. The counter-trades _do not precipitate_ after they leave the rainy +belt, although at a great elevation, until they reach the outward limits +of the trades; and they _do precipitate again_, although they gradually +descend _nearer the earth_, as soon as they become subject to the action +of the currents of an opposite magnetism. Their precipitation is partial +too, even then, and they carry a portion of their moisture through an +atmosphere of the coldest temperature up to the geographical poles. + +A similar result attends the action of the sun in the extra-tropical +regions. Cumuli commence forming in the counter-trade, or at the line +between that and the surface current, at the same time of day that the +diurnal motion of the magnetic needle commences, or the rain clouds form +in the tropics; they continue to enlarge here as there, till about the +same hour of the day that the _needle_ obtains its maximum diurnal +variations; and when the influence of the sun upon the needle ceases, and +it returns to its original status, the cumuli disappear. Hail storms too, +it is said, always, or generally occur in the day time. + +In like manner the sea-breezes and other fair-weather surface winds, rise +in the forenoon with the influence of the sun upon the magnetic currents +and the needle, and die away at nightfall when the influence ceases. + +There are other electro-magnetic, or to speak more correctly, +magneto-electric, effects of the sun's action equally illustrative, which +tend to show that the precipitation at the passing of the trades, is the +result of their action upon each other, aided by the sun, to which we +shall allude when we come to speak of the causes and character of the +surface winds of the extra-tropical regions. + +As, however, this takes place only, or mainly, where the threading +surfaces meet, it is but partial, and the body of the respective polarized +currents pursue their way unaffected, toward the opposite magnetic +pole--and there for the present we leave them. + +Storms sometimes originate in these currents, when concentrated, as in the +West Indies, the China Sea, the Bay of Bengal, and Indian Ocean, while +passing through the rainy belt, and move with the current to the +north-west if issuing on the north side of it, and to the south-west if +issuing on the south side of it, until they respectively get beyond the +extreme limits of the trades, and then they curve to the eastward, +imbedded in and following their current. The peculiar extension of the +land to the east on the northern portions of South America, prevents the +gathering of an aerial gulf similar to the one which we have described to +the north-west, entering upon our division of the continent over the Gulf +of Mexico. It is otherwise in the Indian Ocean, and there the storms are +found issuing from the rainy belt on the southern side, sweeping over the +Mauritius and other islands of that ocean, and _often simultaneously_ with +storms issuing on the north over the Bay of Bengal. Colonel Reid mentions +instances and gives a diagram.[2] + +These storms in milder forms issue from the rain belt at other points, and +may issue any where, but will always be found most extensive and most +violent, that is to say, as hurricanes and typhoons, in the concentrated +volumes of counter-trade on the western side of the great oceans, within a +few hundred miles of the lines of magnetic intensity and no variation, and +when they form in the rainy belt they are highly electric. Most +frequently, however, as we shall see, they form in these currents after +they have issued from the rainy belt, and after they have passed the +extreme limits of the trades and become subject to the circular and +perpendicular magnetic currents which exist north and south of the +longitudinal ones, and which when seen upon the magnetic needle, attract +the filings and cause them to adhere--although but slight attraction or +adhesion takes place where the longitudinal currents exist. + +Such, then, are the atmospheric arrangements and phenomena of the +trade-wind region, and the cause that produces them; such is the character +and cause of the enlarged volume of counter-trade, which spreads out and +blows over our country as permanently as the S. E. trades blow on the +South Atlantic and South America, returning to us the rivers which had run +from us to the sea. + + + + +CHAPTER VI. + + +Coming back now, to a consideration of the course and functions of the +counter-trade after it leaves the northern limit of the surface-trades, we +find it curves to the eastward and gradually assumes about an E. N. E. +course, and becomes a W. S. W. current where it crosses the line of no +variation, and continues on until it passes off over the Atlantic; and +this course and curve is analogous to what may be found true of the +counter-trades every where. It is best illustrated by the course of all +the storms (in the American sense of the word, as distinguished from +thunder showers and other brief rains), which have been traced north or +south of the limits of the trades. It was found by Mr. Redfield in most of +the storms investigated by him, which originated within, or north of the +tropics. + +Doubtless it was the actual course of the others, and that the +investigation was imperfect. All the great autumnal, winter, or spring +storms which have traversed the whole or any considerable portion of the +territory of the United States, east of New Mexico, which have been +investigated by Professors Espy, Loomis, Redfield, or others, have been +found to follow this course. A storm which passed over Madeira, appears +from the investigations of Colonel Reid to have followed the same law of +curvature. + +And so, doubtless, did another which he has described as passing over the +Levant. The storms which supply the winter rains of California and Utah, +reach them by this law of curvature and progress, after the northern +limits of the trades have descended to the south with the sun, so that the +counter-trades of the Pacific may descend to the surface and curve in upon +them. But the absence of a concentration of the counter-trade, and its +deficient action because of its passage over mountain ranges, and their +location so near the northern limit of the trades that their storms can +not expand and become extensive, as well as their weaker magnetic +intensity, prevent their storms from becoming violent, and their supply of +rain is not large and much of it falls in showers. The same is true of the +Barbary States, of Syria, and Persia, and of Southern Europe; and indeed +of all the countries of the globe which lie between the winter and summer +extreme limits of the surface-trades, and without the limits of the two +concentrated counter-trades. Enough appears in the writings of the +meteorologists of Europe to show, that their long continued rains, which +are analogous to our storms and are _preceded by the formation of the true +cirrus of the counter-trade_, follow the same great law of curvature and +progress; although the presence of the Gulf Stream with its mass of south +polar waters on the western side of the British Islands, Denmark, and +Norway supplies them with showers, and fogs, and cumuli from the west and +north-west, and makes the mean of the surface winds of their storms +somewhat variant from ours. A like law reversed prevails in the southern +hemisphere. The storms of New Holland and the Indian Ocean, south of the +limits of the trade, curve to the eastward and travel about south-east, +their _south-west_ being a _clearing off wind_ as our _north-west_ is, and +_precisely similar in all its other characteristics_, where the relation +of magnetic intensity is the same. + +The storms of the Pacific on the S. W. coast of South America, in like +manner travel to the S. E., flooding the western slopes of the mountain +ranges with rain, and aggravated by the intensity of the magnetic currents +at the extremity of the continent in a high latitude, meet the mariner in +the face as he emerges from under the lee of the land and attempts to pass +the Horn. It will ultimately be shown that the precipitation which takes +place, as the storms and counter-trades pass north and east in the +northern hemisphere and south and east in the southern hemisphere, is +owing less to cold than increased magnetic intensity. And all this is the +result of one great uniform law, existing every where, varying in its +phenomena only in consequence of the difference in volume, and +magneto-electric intensity of the portions of the counter-trade, as of the +surface-trade at different places, and the different magnetic intensity of +the local perpendicular and circular currents of the earth over which they +pass, at different periods and at different points. + +Mr. Redfield and Lieutenant Maury have assumed that our S. W. current +comes from the Pacific Ocean. Aside from the adverse evidence which the +investigations of the former in relation to the course of the West Indian +storms, and their curving over the continent, furnish to the contrary, and +that which has herein before been stated in relation to the law of +curvature, it is obvious they are mistaken, for another and conclusive +reason. + +In order to reach us from the Pacific in a direction from S. W. to N. E., +it must pass the table lands and mountain ranges of Mexico and New Mexico, +and it would supply them bountifully, even if it did not thereby leave us +comparatively rainless and sterile. Every where currents passing from the +ocean _over mountain ranges_ part with a large share of their moisture. +Thus the counter-trade which curves over the Andes and over Peru, is +deprived of its moisture and leaves the western coast rainless. So in +degree of the counter-trade which curves over the Himalaya and Kuenlon +Mountains, and from there passes over the Desert of Cobi, to the north and +east--it is deprived by those elevated ranges of its moisture. So the +mountains on the south-western coast of South America are drenched with +rain, while Patagonia, which lies on the east of them is comparatively +dry. And so of every other country similarly situated. + +Now the mountain ranges and table lands of Mexico are not thus supplied +with moisture. For the space of four months in Southern and less in +Northern Mexico, and in summer, and while the belt of the tropics is +extended up over them, they have rain and in daily showers which _travel +up from the south_, indicating the course of the counter-trade. (See +Bartlett's Personal Narrative, vol. ii. p. 286.) At other seasons, and +while we are bountifully supplied, they are dry. In short, there are no +two portions of the earth that differ more widely in regard to their +supply of moisture, and all their climatic characteristics and relations. +It is therefore, according to all analogy, impossible that our +counter-trade should come from the South Pacific across the continent and +below 35°, and in this also those gentlemen are mistaken. + +Messrs. Espy and Redfield recognizing the existence of "a prevailing" S. +W. current, but considering the surface-winds beneath it as the principal +actors in producing the atmospherical conditions and changes, have +attributed no office to that current, except that of giving direction and +progression to our storms. This is their great mistake. It plays no such +unimportant part in the philosophy of the weather, as we have already +incidentally seen, and will proceed still further to consider. + +_All our storms originate in it._ This we may know from analogy. + +_Where there is no counter-trade, outside of the equatorial belt of rains, +and within influential distance of the earth, there are neither storms nor +rain._ So, when, as we have seen, the concentration of the volume of +northern counter-trade in the West Indies, gathered by the hauling of the +S. E. trades more from the east, as they approach the central belt, +diminishing the volume of the counter-trade over the North Atlantic, the +calms and drought of the horse-latitudes are found. And when the +counter-trade is small in volume and weak in intensity, by reason of the +fact that the surface-trades from the opposite hemisphere which constitute +it, formed upon land where evaporation was small, as upon Southern Africa +and New Holland, or formed where the magnetic intensity was weak, or +passed over mountain ranges in their course, the annual supply of rain, +the ranges of the barometer, and the alternations of atmospheres +conditions are remarkably less. + +We have already seen where the rainless portions of the earth are, and why +they are so; because those lying north of the northern limit of the +equatorial rainy belt were yet too far south to be covered by the line of +extra-tropical rains; or in other words, too far south to be uncovered by +the surface N. E. trades and the longitudinal magnetic currents, and to be +covered by the counter-trades in contact, or nearly so with the earth, and +influenced by the perpendicular north polar magnetic currents. Thus we +have seen that the rains of Southern Mexico were summer rains, due to the +northern extension of the equatorial rainy belt; those of California were +winter rains, due to the southern extension of the extra-tropical rains +following the N. E. surface trades. We have also briefly alluded to the +fact that either side of the equatorial rainy belt, evaporation is going +on for months under a vertical sun, without precipitation--unless it be +from an occasional brief storm of great intensity which originates in that +belt at the line of it, and passing on in the counter-trade, reverses, for +the time being, by its concentrated and powerful action, like a magnetic +body introduced into the field of another magnet, the surface-trades. Mere +evaporation then, does not produce the storm, or shower, or rain, where +most active in the dry torrid zone. It may be said that those dry portions +are, for the time being (as the rainless portions of the earth are +continually), within the operation of the surface-trades, and that +therefore the evaporated moisture is carried away by them toward the +equatorial rainy belt. Precisely so; but why carried away? Why should it +not condense, occasionally, at least, and drop the rain as it passes +along, if a great supply of moisture from excessive evaporation could +furnish rain. Perhaps it may still be said it is going from a cold to a +warm section. This is not true, as we have shown. + +But, it may be said that the rainless regions at any rate receive no +moisture, and therefore can not supply any by evaporation. This would not +meet the case, as it would still be true that when the rainy belt has left +a given spot, the dry weather sets in with excessive evaporation, and the +north-east trades in summer, blowing from the countries lying north of the +rainless regions, and which have been supplied during the interval by the +extra-tropical rains, and are loaded with evaporation, are passing over +the rainless regions on their way to enter the central belt. So blow the +N. E. trades from the Mediterranean, and the Barbary States _over the +Desert of Sahara_ and into the rainy belt south of it; but drop no +moisture on their way, because exposed to no magnetic currents of an +opposite polarity. + +But it is not true that all the rainless regions are without evaporation. +Egypt is an exception. The annual freshets of the Nile saturate its +central valley, and vast reservoirs of water are saved from it and let out +over its surface, and it all evaporates, but produces no rain. And so are +large quantities turned aside and scattered over the bottom lands of +Northern Mexico, and other countries, during the dry season, and their +evaporation furnishes no rain. Hygrometers and dew points are of no +consequence there--nor are they of any, on either side of the rainy belt, +where six perpendicular feet of moisture is evaporated in six months. + +Again we have alluded to a strip of coast on the Pacific west of the +mountain ranges of South America, lying partly in Peru, partly in Bolivia, +and partly in Northern Chili, which, although long and narrow, washed by +the broad Pacific Ocean, is without rain. South America has no other +_wholly_ rainless region, so far as is known. A part of this region would +lie between the equatorial belt of rain, and the southern extra-tropical +one, and never be covered by either; but the volume of N. E. trades from +the Atlantic, although from the make of the land not concentrated to so +great an extent as the volume of S. E. trade on the north, and therefore +not so liable to hurricanes and other violent storms, is yet sufficiently +so to carry the southern line of the equinoctial rainy belt down in winter +to the summer line of extra-tropical rains, and give a supply of rain to +all the continent--leaving no strictly rainless region south of the +equatorial rainy belt and east of the Andes. Those mountains, however, +present a barrier to its south-western progress which it doubtless passes +to some extent, but deprived of its moisture, and unable to supply the +rainless coast region of Peru, Bolivia, and Northern Chili. There is, +therefore, a portion of this rainless line of coast which is within the +region of extra-tropical rains, over which a portion of the N. E. trades +of the Atlantic, as a counter-trade, should or do, curve, and where there +should therefore be extra-tropical rains. It is washed by the Pacific, an +evaporating surface, and westerly and south-west breezes are drawn in from +that ocean over it. Why then is it rainless? The only reason which can be +assigned why rain does not fall there is that the high mountain ranges of +the Andes intercept and perhaps in part divert the counter-trade, and +deprive that portion of it which passes them, of its moisture, by that +reciprocal action of opposite polarities which takes place whenever and +wherever the trade approaches so near the earth; and it curves over the +narrow line of coast with the feeble condensation, and imperfect forms, +and varied coloring which mark so peculiarly the rainless clouds of that +region. (See Stewart's Journal of a Voyage to the Sandwich Islands, page +72.) + +Again, it is estimated, and on reliable data, that twelve perpendicular +feet of water are annually evaporated from the surface of the Red Sea, +between Nubia on one side, and Arabia on the other; yet they are both +rainless countries, except so far as the inter-tropical belt of rains +extends up on to a small portion of them. The moisture of evaporation, +floated up from a surface covered by the surface-trade is invariably so +combined as to remain uncondensed till it has passed south into the +equatorial rainy belt, and over to the opposite hemisphere, and been +exposed to the currents of an opposite magnetism. + +Again, the N. E. trades extended up in summer over the Mediterranean Sea, +an evaporating surface, blow over the Barbary States in June and July, but +furnish no rain. And so of the S. E. or N. E. trades which blow over +Brazil and other countries in the absence north or south of the tropical +belt of rains. + +It is obvious from these facts--and more like them might be cited--that +mere evaporation, however copious or long continued, does not make the +storm or shower in the locality where it takes place, and _without the +existence and influential agency_ of a counter-trade; and that _reciprocal +action_, whatever it may be, that takes place _between it and the earth_. + +Again, our own experience is conclusive of this. We have no surface-trade +north of 30°, and yet a long drought and great evaporation may follow a +wet spring. Belts of droughts and frequent rains occur every year in +different portions of the country side by side, and _the dividing line +follows the course of the counter-trade_, and is sometimes distinctly +marked for weeks. When a change occurs in the counter-trade, whether from +causes existing there or the influence of terrestrial magnetism (in +relation to which we shall inquire hereafter), showers form or storms come +on: until it does they will not. Efforts at condensation will occasionally +appear, but they will be feeble and ineffectual, and occasion a repetition +of the axiom that "all signs fail in a drought." And we may know it from +direct observation. + +The first indications of a storm, and of most if not all showers, are +observable in the counter-trade. These indications, so far as they are +visible, are of course to be looked for in the west; although the +direction and character of the surface-winds are often indicative of these +changes when not visible at the west as we shall see. + +The indications are those of condensation, and vary very much in different +seasons of the year. It is not my purpose in this place to examine them +particularly. They will be alluded to hereafter under the head of +prognostics. Suffice it now to say, then, that whether it be the long +threads or lines of cirrus which occur in the trade in the winter after a +period of severe cold, following the interposition of a large volume of N. +W. cold air and the elevation of the counter-trade; or the forms of cirrus +which occur at other times and other seasons; or whether it be the +ordinary bank at night-fall, or the evening condensation which makes the +"circle" around the moon, or the morning cirro-stratus haze which +gradually thickens, passes over and obscures the sun, all which may be +followed by the easterly scud and winds: they are alike condensation in +the trade, the advance or forming condensation of a storm or showers. + +The state of the weather, whether hot or cold, is extensively affected by +this trade current. As we have already suggested, the mere presence of the +sun in its summer solstice, or its absence in winter, is not an adequate +cause of all the sudden and various changes to which we are subject. The +state of the counter-trade, which is always over, or _within influential +distance of us_, and sometimes probably in contact with us--the nature of +the surface-winds which it is at any given time creating and attracting +around us, and the electric condition of the surface-atmosphere _induced_ +by it, or by the immediate action of the earth's magnetism, produce those +sudden changes which mark our climate. When no intervening surface-winds +elevate it above us, and there is no storm or other condensation within +influential distance, it induces the gentle balmy S. W. wind of +spring--the cooling S. W. wind of summer--the peculiar Indian summer air +of autumn, or the comparatively moderate, although cold, open weather of +winter. If there be a partial tendency to condensation in it, the cumuli +form under the magnetic influence excited by the sunbeams from ten to +three o'clock in the day, and float gently away to the eastward, +disappearing before night-fall. If the disposition to condensation is +stronger, whether inherent or induced by an increased local activity of +terrestrial magnetism, these cumuli will increase toward night-fall, or +earlier, and terminate me showers; and if it is in a highly electrical +state, the still oppressive sultriness which precedes the tornado, and +that devastating scourge may appear. If this disposition to condensation +becomes extensive, cirri form and run into cirro-stratus, or they extend, +coalesce, and form stratus; the surface-wind will be attracted under them, +the thermometer fall in summer or rise in winter, and a storm begin. +Intense action and sudden cold may exist in and under this counter-trade +over the southern portion of the country, while all is calm, warm, and +balmy at the north. Heavy snow storms sometimes pass at the south when +there are none at the north, and a corresponding state of the weather +follows. If a large body of snow fall at the north, the winter is cold, +regular, and "old fashioned;" if little snow falls at the north and more +at the south, the winter at the north is open and broken. I have known the +ice make several inches thick at Baltimore and Washington, when none could +be obtained for the ice-houses on the Connecticut shore of Long Island +Sound. In short, although heat and cold are mainly dependent upon the +altitude of the sun, aided by the other arrangements we have alluded to, +yet the counter-trade, and the reciprocal action which takes place between +it and the earth, are most powerful agents, mitigating the rigors of +winter, bringing about the changes from cold to warm weather which the +sun is too far south to produce. And on the other hand, by this reciprocal +action, producing the electrical phenomena, the gusts, the tornadoes, the +hail storms, and the cool seasons of summer, and the period of intense +cold in winter. + +_All our surface-winds, except the light, peculiar W. S. W. wind which is +felt where the counter-trade is in contact with the earth, and which is a +part of it, and perhaps the genuine N. W. wind which is very peculiar, are +incidents of the trade, and are due to its conditions and attractions._ We +have already said this was true of the easterly wind and scud of a +storm--it is alike true of all. The storm winds east of the Alleghanies +are usually, though not always, from the eastward. They are sometimes from +the southward, as they doubtless are still more frequently in the interior +of the continent. + +There is occasionally a southerly afternoon wind, followed by short rains +in spring and fall, or a succession of showers in summer, which is rather +a precedent wind than a storm wind; blowing toward and under an advance +portion of the storm at the north, and hauling to the eastward when the +rain sets in, or to the westward when the showers reach us. + +When there are no storms, or showers, or inducing electric action in the +counter-trade, within influential distance to disturb the surface +atmosphere, it is calm. If a storm approaches, or forms within inducing +distance, the surface atmosphere is _affected_ and _attracted toward the +storm_, from one or more points, and "blows," as we say, toward and under +it. It commences blowing first nearest the storm, and extends as the +storm travels, or becomes more intense and extends its inducing influence. +I have repeatedly noticed this in traveling on steamboats and railroads +running _toward_ or _from_, and in several instances _through_ a storm, +and telegraphic notices and other investigations prove it. The point from +which the surface atmosphere is attracted and blows, depends very much +upon the position of the storm in relation to bodies of water and the +point of observation, and its shape; and the force with which it may blow +will depend much upon its intensity. + +Let us take an instance or two by way of illustration of all these points; +and as I have given instances of summer in the introduction, we will take +those of winter. It is January of an "old fashioned winter;" the snow is +about three feet deep in Canada, about one foot in Southern New York, and +a few inches in Philadelphia, and so extends west to the Alleghanies at +least. For several days the sky has been clear, the thermometer rising in +the day-time, in the vicinity of New York to about 25° Fahrenheit, falling +at night to about 6°, with light airs from the N. W. during the middle and +latter part of the day; the counter-trade and the barometer both running +high; cold but pleasant, steady, winter weather. There is a warm +south-east rain and thaw coming, as one or more such almost invariably +occur in January. How coming? The sun is far south, and shines aslant, but +through a pure and windless atmosphere; he has tried for several days to +melt the snow from the roof; a few icicles are pendant from the eaves; +but the body of the snow is still there. How can a thaw come? not from the +sun, surely. No, indeed, not from the action of the sun directly, upon our +country, nor from the Atlantic or the Gulf Stream which is off our coast. +But a portion of the current of counter-trade is coming, heated by his +rays and the warm water in the South Atlantic, in an intense +magneto-electric state, capable of inducing an electro-thermal change in +the surface atmosphere which it approaches, and of being reciprocally +acted upon by the north polar terrestrial magnetism. It is now over +Northern Texas and Western Louisiana, it will be here day after tomorrow. +The day passes as the day previous had passed; the sleigh-bells jingle +merrily in the evening; the moon shines clear all night; the storm is +coming steadily on, but its influence has not reached us, and the morning +and midday are like those which preceded it. As nightfall approaches, +however, the thermometer does not fall as rapidly as on the day previous; +the sun shines dimly and through lines of whitish cirrus cloud extending +from the horizon at the west, appearing darker as the sun descends and +shines more _horizontally_ through them--perhaps mainly in the N. W.--and +which extend up and over toward the E. N. E. The air next the earth begins +to feel raw; it is changing, not from warm to cold, but _electrically_ +from positive to negative; and dampening, from a tendency to condensation +by induction, as we shall see--the same condensation which in warm +weather may be seen on flagging stones, and walls, and vessels containing +cold water. The advance cirrus condensation of the storm is over us and +affecting us; the earth too is affecting the adjacent atmosphere by action +extended from beneath the storm. Still there is no wind, although sounds +seem to be heard a little more distinctly from the east, and so ends the +day. Evening comes, and the moon wades in a smooth bank of cirro-stratus +haze, with a very large circle around her; the cirrus bands of haze have +coalesced and formed a thin stratus. The storm is coming steadily on, its +condensation is seen to be thicker as it approaches, it is now raining +from one hundred to one hundred and fifty miles to the west, but we do not +know it. + +That it is about to storm all believe, for all are conscious of a change. +The candle if extinguished will not relight as readily, if at all, on +being blown; there is a crackling almost too faint for snow in the fire; +the sun did not set clear; the old rheumatic joints complain, and the +venerable corns ache. + +Morning comes, and the storm is on. The wind is blowing from the S. E., +the scud are running rapidly from the same quarter to the N. W., the +thermometer continues rising, and it rains. The storm has reached us and +the thaw has commenced. Gradually, as the densest portion of the storm +cloud reaches us, it darkens; the scud are nearer the earth, and run with +more rapidity; the rain falls more heavily and continuously, and by the +middle of the day a thick fog has enveloped the earth; the wind is dying +away, and the trade itself, with its southern tendency to fog, has settled +near us; the barometer has fallen, the thermometer is up to fifty degrees, +the water is running down the hills, the snow is saturated with water and +is disappearing under the influence of the fog, the rain, and the warm +air. Evening comes; the south-east wind and the rain have ceased; the rain +clouds have passed off to the eastward; the fog has followed on and +disappeared; there is a light trade air from the S. W.; the moon shines +out, and a few patches of stratus, broken up into fragments and melting +away, are following on in the trade: the storm is past. + +Hark! to the tones of Boreas as he bursts forth from the N. W., and +rushing, whistling, howling, dashes on between the trade and the earth, +following the storm. Now the barometer rises rapidly, the thermometer +falls, and in an incredibly short time all is congealed, and cold and +wintery as before. The cold N. W. wind has again interposed between the +trade and the earth; the trade is elevated a mile or more above it and is +entirely free from its influence and from condensation; the deep blue of a +sky "as pure as the spirit that made it" is over us, and steady winter +reigns again. + +It is obvious that there was nothing in the action of the sun upon our +snow-clad country, to induce the thaw or the storm. It began, continued, +approached, and passed off to the N. E. in the counter-trade. The S. E. +wind which existed every where within its influence: in the interior +States, Missouri, Illinois, Indiana, Ohio, Michigan, and in Canada, as +well as upon the Atlantic coast, commencing in the former earlier than +upon the last, was the result of its induction and attraction. Of the N. +W. wind that followed we shall speak hereafter. If any one doubts whether +this be a true sketch let him examine the investigation of a storm +published by Professor Loomis, or observe for himself hereafter. If, +however, the storm of Professor Loomis is referred to, it should be +remembered that his notes show the occurrence of a slight distinct snow +storm at the N. W. stations one day in advance of the principal storm. The +latter appears first as rain at Fort Towson, on the nineteenth, moving +north and curving to the east--its center passing near St. Louis, and +south of Quebec, and the whole storm enlarging as it advanced. + +Take another instance. Since the thaw it has not been quite as cold as +before; but the rain-soaked snow is hard and solid, the ground, where the +snow was blown or worn off, icy and slippery--the thermometer falls during +the night to about 12°, and rises to about 30°; the sun makes no +impression upon the snow; the firmament is of the deepest blue, the +borealis at night vivid. "O, for a storm of some kind, to mitigate the +still severe cold;" for the thaw has made us more sensitive, and storm +winds do blow warm in their season. But patience, it will come. Another +day, or two, perhaps, pass: the sun rises as usual, the thermometer has +the same range still. "Long cold snap," we exclaim; "how long will it +last?" + +A change is coming, but this time it will snow. About an hour or two after +sunrise the cirrus threads are discoverable again in the west, but now +they are most numerous in the S. W. As the day passes on they thicken and +advance toward the E. N. E., the sun begins to be obscured, the +thermometer rises, and it slowly "_moderates_." There is a snow storm +approaching from the S. W. + +But the thermometer rises slowly; it must get up to 26° or 28° before it +can snow much. I have known in one instance, at Norwalk, a considerable +fall of snow, although much mingled with hail, when the thermometer stood +at 13° above zero, and one, a moderate fall, some two inches, with it at +24°, but these were exceptions. The snow range of the thermometer on the +parallel of 41° north latitude, and south of it, is from 26° to 30° above +0°; when colder or warmer it may snow to whiten the ground, or perhaps +barely cover it, but usually rains or hails. We have seen that in the +polar regions, according to Dr. Kane, it is about zero, but the rise of +the thermometer there, previous to the snow, was about the same as here, +_i. e._, from 15° to 25°. This fact is instructive. Since the foregoing +was written, and on the 7th of February, 1855, a snow-storm of +considerable length set in, with the thermometer at 5°, and continued more +than twenty-four hours, the thermometer gradually rising. The snow was +very fine, like that described by Arctic voyagers as falling in extreme +cold weather. + +As the dense and darker portions of the storm approach, and although the +sun is obscured, and the ground frozen, it continues to moderate, and at +evening, when the thermometer is up to 28°, and the dense portion of the +storm has reached us, gently and in calmness the snow begins to fall. +Perhaps a light air following the storm, or the presence of the trade near +the earth, at first inclines the snow-flakes to the eastward. This is +frequently so at the commencement of snow storms. Ere long, however, the +wind rises from the N. E., and the snow is driven against the windows, +rounded and hardened by the attrition of its flakes upon each other, in +their descent through the eddying and opposite currents. The next day we +rise to witness a heavy fall of snow, perhaps, and a continued driving N. +E. storm, in full blast; the snow whirling and settling in drifts under +the lee of every fence or building. + +Can it be, you ask, that this driving wind is but an _incident_ of the +storm? the result of _attraction_, while the storm clouds are sailing +quietly and undisturbed on in the counter-trade above, directly over the +gale which is blowing below? It is even so. Nor has it "backed up," as it +is termed by those who have ascertained that it has commenced snowing +first, and cleared off first, at a point west of them. You saw, or might +have seen, the cirro-stratus cloud passing to the E. N. E. in the +afternoon, and until the snow-flakes filled the air, and the clouds became +invisible. You may still see that the wind will die away before the storm +breaks, and "come out" gently from the S. W., unless it should back into +the northward and westward, and in either event you may see the last of +the storm clouds, as you did see, or might have seen the first of them, +pass to the eastward. Toward night the wind dies away, and the storm +passes off abruptly, or the sky becomes clear in the N. W. Now you may see +the smooth stratus storm cloud, continuous, or breaking up into fragments +and passing off to the east, even at the edge which borders the clear sky +in the west or north-west, to be followed that evening or the next day, by +the north-west wind and its peculiar fair-weather scud. + +I have given these as instances illustrating the manner in which rain and +snow storms originate the surface easterly winds in winter. + +But it must not be supposed that they commence with precisely the same +appearances in every case in winter; much less in summer. There is very +great diversity in this respect, in different seasons, and in different +storms during the same season. A great many different and accurate +descriptions might be given, if time and space would permit, which all +would recognize as truthful. Very frequently in summer, and sometimes in +winter, the wind will set in from the eastward, and blow fresh toward a +storm, before the condensation in the trade, which forms the eastern and +approaching edge of the storm, has assumed the form of a distinct cloud. +Not unfrequently, when it is calm next the surface, a narrow stratum of +easterly wind, a half a mile or a mile above the earth, may be seen with a +continuous fog, condensing, but not in considerable patches like the +usual scud, running with great rapidity toward the storm. Such a stream of +fog blew with great rapidity for thirty-six hours toward the storm which +inundated Virginia and Pennsylvania, in 1852, and carried away the Potomac +bridge at Washington. Such a stream of fog was visible the evening before +the great flood of 1854, which inundated Connecticut, and curried away so +many railroad and other bridges. I have also seen such a stream of fog +running at about the same height, when it was calm at the surface, from +the S. W. toward a violent storm which formed over central New +England--and from the north toward a heavy storm passing south of us. Such +strata form, as far as I have been able to discover, the _middle current_ +of storms which are accompanied with very heavy falls of rain. These +double currents are much more common than is supposed. East of the +Alleghanies, short and heavy rain storms, which commence north-east, +hauling to the south and lighting up about mid-day _after a very rainy +forenoon_, frequently have a S. E. or S. S. E. middle current of this +character, which involves the whole surface atmosphere when the storm has +nearly passed, and the N. E. wind dies away, and the wind seems to haul to +the S. S. E. and S.; so that it is rather the prevalence of a _different_ +and _coexisting current_, than a hauling of the _same wind_, which marks +the period of lighting up in the south. + +Sometimes the easterly wind will set in and blow a day or two before the +border of the storm reaches us. Sometimes the storm is passing, or will +pass, in its lateral southern extension, south of us, and the +condensation in the trade extends over us sufficiently dense to induce an +easterly current beneath it, but not dense enough to drop rain, and then +we have a dry north-easter. I can not, within the limits I have +prescribed, allude to all the peculiarities attending the induction and +attraction of an easterly wind, by the storm in the counter-trade. They +are readily noticeable by the attentive and discriminating observer, and +their existence and cause is all with which I have to do at present. + +Winds from the north, or any point from N. N. E. to N. N. W., are +comparatively infrequent in the United States, east of the +Alleghanies--though it is otherwise in the vicinity of the great lakes. + +Sometimes the wind "backs," as sailors term it, during a N. E. storm, from +the N. E. through the N. N. E., N., and N. N. W. to N. W. When this takes +place, it is toward the close of the storm. Occasionally, though very +rarely, it continues to storm after the wind has passed the point of N. N. +E., and until it gets N. W. I have known a few instances in the course of +thirty years, and but a few. They are exceptions--rare exceptions. When +the wind thus backs from the N. E. to the N. W. through the N., you may be +very certain that the body of the storm, or at least the point of greatest +intensity and greatest attraction, is at the time passing to the southward +of you. This is most commonly the course of the wind when the storm +extends far south and lasts several days, and does not extend north far, +or if so, with much intensity, beyond the point of observation. The +change of the wind is explained by the situation of the focus of intensity +and attraction, to the south of the observer, and its passage by on that +side. + +Probably in locations further north and (as I think I have observed) south +of the lakes, it may be more frequent than upon the parallel of 44° east +of the Alleghanies (which is as far north as I have observed), inasmuch as +the further north the locality, the more likely storms and other +disturbances in the counter-trade will be to pass to the southward of it. + +Between the N. E. and S. E. the wind may blow from any point, before and +during storms, and in a clear day in the morning, as a light variable +breeze, or, after mid-day, toward approaching showers. I have known it +blow all day during a storm from due east; to change back and forth +between south-east and north-east, and to blow for hours from any +intermediate point--as different portions of the storm were of different +intensity, and exerted a more or less powerful inducing influence; and +doubtless this often takes place at sea. It depends upon the situation of +the focus of attraction of the storm, its shape relative to the particular +locality, and with reference to the atmosphere east of it, and peculiar +local magnetic action; or, as is sometimes the case in low latitudes, is +owing to the fact that the storm is made up of many imperfectly connected +showers, which have different force, and induce changeable and baffling +winds. + +The inducing and attracting influence of the approaching storm is exerted +sooner, and with most force, upon the surface atmosphere, over bodies of +water like the ocean and the lakes. Thus, the wind will set from the +eastward toward an approaching storm out upon Long Island Sound, for hours +before it is felt upon either shore; and when all is calm in the evening +on land, and often before the moon forms a halo or circle in the milky +condensation of the approaching storm, or any sign of condensation is +visible, the breaking of the waves upon the shores may be heard. Doubtless +this may be observed on the shores of the Atlantic at other points. + +This power of attracting the surface atmosphere from bodies of water like +the ocean and the great lakes, will account for two apparent anomalies, +mentioned by Mr. Blodget in a valuable and instructive article read to the +Scientific Convention, in 1853, regarding the annual fall of rain over the +United States. + +First--the influence of mountains in extracting the water from the +atmospheric currents which pass over them, is well known and readily +explainable. Mr. Blodget, however, found that the source of our rains, +whatever it might be, when it reached the Alleghanies, was so far +exhausted of its moisture that those mountains extracted less from it than +fell to the westward, by some five to ten inches annually; and that the +fall of rain upon them was less than upon the Atlantic slope eastward of +them, to the ocean. This does not accord with observation elsewhere, but +is easily explained. As the storm approaches the ocean, it attracts in +under it the surface atmosphere of the ocean, loaded with vapor, +condensing in the form of fog and scud, as it becomes subject to the +increasing influence of the storm. Although the scud and fog would not of +itself make rain, it aids materially in increasing the quantity of that +which falls through it. The drops, by attraction and contact, enlarge +themselves as they pass through, in the same manner as a drop of water +will do in running down a pane of glass which is covered with moisture. +The small drop which starts from the upper portion of a fifteen-inch pane, +will sometimes more than double its size before it reaches the bottom. _It +is by this power of attracting the surface atmosphere, which contains the +moisture of evaporation, under it, and inducing condensation in it, that +the moisture of evaporation which rarely rises very far in the atmosphere +is made to fall again during storms and showers._ This attraction of a +moist atmosphere from the ocean accounts for the excess of rain on the +east of the Alleghanies, compared with its fall upon them. So the great +valley of the Mississippi is comparatively level, and less of its water +runs off than of that which falls upon the Alleghanies. There is, +therefore, more moisture of evaporation in the atmosphere of the former to +be thus precipitated and add to the annual supply of rain upon that +valley, and it exceeds that which falls upon the Alleghanies. Those +mountains, too, are elevated but about 1,500 feet above the table-lands at +their base, and exert little influence on the counter-trade. If they, were +6,000 or 8,000 feet high, a different state of things would exist. + +Second--Mr. Blodget found the quantity of rain which fell in Iowa, and to +the south and west of the lake region, to be greater than fell over the +lake region itself. This is doubtless in part owing to the same cause. The +counter-trade, in a stormy state, attracts the surface atmosphere from the +lake region, with its evaporated moisture, before it arrives over it, and +therefore more rain falls S. W. of the lake region than upon it. This +power of attracting the surface wind of the ocean in under it, produces +the heavy gales which affect our coast, and which are rarely felt west of +the Alleghanies to any considerable degree; and a storm coming from the W. +S. W., extending a thousand miles or more from S. S. E. to N. N. W., may +have the wind set in violently at S. E. on the _southern coast first_, and +at later periods, successively, at points further north, and thus induce +the belief that the storm traveled from south to north. + +Mr. Redfield finding that some of the gales which he investigated, +particularly that of September 3d, 1821, did not extend far inland, and +commenced at later periods regularly, at more northern points, concluded +that the gale traveled along the line of the coast to the northward. In +this, and in relation to the storm of 1821 (and perhaps some others), he +has been deceived. My recollections of that storm are accurate and +distinct. But I shall recur to this again when I come to speak of his +theory. + +Toward storms, or belts of showers which would be storms if it were not +summer and the tropical tendency to showers active in the trade, which +pass mainly to the north of us, or commence north and pass over us, +condensing south while progressing east, the wind may commence blowing +before the body of the storm reaches us, from any point between south by +west and south east, particularly in the summer season and in the +afternoon. When the rain in a storm of this character sets in, in the +night, it will sometimes haul into the S. E., if the focus of attraction +be situated north of us, and so remain until just before the storm is to +break. + +There are, however, a class of southerly summer winds which deserve more +particular notice. For two or three months in the year--say from the +middle of June to the 20th of August--storms on the eastern part of the +continent, except in wet seasons, are rare, and most of our rain is +derived from showers. During these periods belts of drought are frequent, +sometimes in one locality, and sometimes in another, extending with +considerable regularity from W. S. W. to E. N. E. in the course of the +counter-trade, while rain falls in frequent and almost daily showers to +the northward or southward of them. If the daily rains are at the north, +over the belt of drought, S. S. W. and S. W. by S. winds blow, sometimes +with cumuli or scud, during the middle of the day and afternoon, to +underlie the showery counter-trade on the north of the line of drought. +Thus, sometimes nearly every day for several days, the evaporated moisture +of the dry belt will be carried over to increase the store of those who +have a sufficient supply without. During the latter part of the afternoon +the clouds in the west may look very much like a gathering shower, but the +attractions of the counter-trade fifty or one or two hundred miles to the +north, will absorb them all, and at nightfall the wind will haul to the S. +W. on a line with the counter-trade, and die away. + +If there be a drought on any given line of latitude, and frequent showers +or heavy rains at the south of it, although there may not be a like +surface-wind, with cumuli and fog, blowing from the north toward it, yet a +general, gentle set of the atmosphere, from the N. N. W., or N. W., or +other northerly point, toward the belt of rains, some distance above the +earth, will often be observable, with a barometer continually depressed, +and perhaps a cool atmosphere. + +During set fair weather, when the attracting belt of rains is far north, +on the north shore of Long Island Sound, the wind, like a sea breeze, will +set in gently from about S. S. E. or S. by E. in the forenoon, blowing a +gentle breeze through the day, and hauling to W. S. W. on a line with the +trade at nightfall, and dying away. During a drought I have known this to +happen for seventeen successive days. It is obvious to an attentive +observer that this is the result of the influence of the sun in exciting +the magnetic influence of the earth, and producing a state of the trade +not unlike that which induces the formation of cumuli, and which attracts +the surface atmosphere from the Sound in over the land: for the _tendency +to cumulus condensation precedes the breeze_, and the breeze is often +wanting in the hottest days where no such tendency to the formation of +cumuli exists. The same is true of sea breezes elsewhere. They do not blow +in upon some of the hottest surfaces. Where they do exist, they do not +always blow, but are wanting during the hottest days; and careful +observers have identified their appearance with the formation of cumuli, +or other condensation, upon the hills inland. They are not, therefore, the +result of ascending currents of heated air. + +The received theory regarding sea and land breezes is a mistaken one in +another respect. There is no such thing as a land wind corresponding in +force to, and the opposite of, the sea breeze--occasioned by the +comparative warmth of the ocean. These breezes blow mainly within the +trade-wind region. Of course they are either beneath the belt of rains or +the adjoining trades. They are said to be, and doubtless are, most active +and strongly marked on lines of coast, particularly the Malabar coast, and +where the trade-winds are drawing usually from them. In the day-time, when +the action of the sun increases the action of the magnetic currents upon +the land, or there are _elevations inland_ which approach the +counter-trade, and especially if it is elevated near the coast, as the +Malabar coast is by the Ghauts, the attraction of this atmosphere over it +_reverses the trade_, or inclines it in upon the land, and it blows in +obliquely or perpendicularly, according to the relative trending of the +coast and the direction of the surface-trade. Thus, where islands are +situated within the range of the trades, the latter will be _reversed_ +during the day on the _leeward_ side, but continue to blow as land winds +during the night. So they are sometimes deflected in upon the land on the +sides, during the day, and in like manner return to their course in the +night. So, too, the north-east trades of Northern Africa, are occasionally +(though feebly where the coast is flat) deflected during the day-time, and +blow in as N. W. winds. Upon the southern coast of Africa the S. E. trade +is deflected, and blows in as a S. W. wind. Upon the south-western coast +of North America, the N. E. trades are deflected in like manner, and so +are the S. E. trades upon the western coast of South America. Where the +coast mountain ranges are very elevated, as upon the western coast of the +American continent, this attracting influence and consequent deflection +extends to a considerable distance seaward, and hence the westerly winds +of California, etc. It must be understood that we are now speaking of the +winds which blow within the range and during the existence of the +trade-winds or the presence of the dry belt--for the trades are not always +perceptible on the land. Captain Fitzroy thus describes the sea breezes of +the western coast of Peru, at 23° south latitude. "The tops of the hills +on the coast of Peru are frequently covered with heavy clouds. The +prevailing winds are from S. S. E. to S. W., seldom stronger than a fresh +breeze, and often very slight. _Sometimes during the summer, for three or +four successive days, there is not a breath of wind, the sky is +beautifully clear, with a nearly vertical sun._ On the days that a sea +breeze sets in, it generally commences about ten in the morning, then +light and variable, but gradually increasing till one or two in the +afternoon. From that time a steady breeze prevails till near sunset, when +it begins to die away, and soon after the sun is down there is a calm. +About eight or nine in the evening _light winds_ come off the land, and +continue till sun-rise, when it again becomes calm until the sea breeze +sets in as before." + +To illustrate this further, I take the following letter from Professor +Espy's Philosophy of Storms: + + CLINTON HOTEL, N. Y., Dec. 20, 1839. + + TO PROFESSOR ESPY, + + DEAR SIR,--Understanding you are desirous of collecting curious + meteorological facts, I take the liberty of communicating to you what + I saw in the month of December, 1815, at the Island of Owhyhee. I lay + at that island in the Cavrico Bay,[3] in which Captain Cook was + killed, three weeks, and every day during that time, very soon after + the sea breeze set in, say about nine o'clock, a cloud began to form + round the lofty conical mountain in that island, in the form of a + ring, as the wooden horizon surrounds the terrestrial artificial + globe, and it soon began to rain in torrents, and continued through + the day. In the evening the sea breeze died away and the rain ceased, + and the cloud soon disappeared, and it remained entirely clear till + after the sea breeze set in next morning. The land breeze prevailed + during the night, and was so cool as to render fires pleasant to the + natives, which I observed they constantly kindled in the evening. I + was particularly struck with the phenomena of the cloud surrounding + the mountain, when none was ever seen in any other part of the sky, + and none then till after the sea breeze set in, in the morning, which + it did with wonderful regularity. The mountain stood in bold relief, + and its top could always be seen from where the ship lay, above the + cloud, even when it was the densest and blackest, with the lightning + flashing and the thunder rolling, as it did every day. I passed up + through the cloud once, and I know, therefore, how violently it + rains, especially at the lower side of the cloud. This rain never + extends beyond the base of the mountain;[4] and all round the horizon + there is eternally a cloudless sky. The dews, however, are very + heavy, and there seems to be no suffering for want of rain. That this + state of things continues all the year, I have no doubt, from what an + American, by name Sears, who had spent four years there, told me; he + had seen no change in regard to the rain. + + CALEB WILLIAMS. + + Providence, R. I. + +Similar citations might be made to show that the sea breeze is induced by +the same cause which forms the clouds over the land--that it is frequently +wanting for three or four days under a vertical sun, and that the land +breeze blows gently and not with corresponding force where there is no +surface trade, or where it is deflected, not reversed. + +A succession of showers passing across the country to the north, within +one hundred to one hundred and fifty miles, almost always produces a +southerly wind to the southward of them. There is more that is peculiar +about these belts of showers. Although they consist of large +highly-electrified cumuli, there is a strong tendency to cirro-stratus +condensation in the lower part of the trade over them; and it is that +condensation rather than the cumuli, which attracts the surface atmosphere +from the south. They would be storms, if the atmosphere had not a +summer-tropical tendency to showers. There is, too, a tendency in these +belts to extend to the south, and it is generally, as far as I have +observed, the extension southerly of those belts, by the formation of new +showers which terminate the "hot spells" or "heated terms" of mid-summer. +The very oppressive and fatal one of the summer of 1853, was, in +character, a type of all--although exceeding them in severity. The first +three or four days were calm, hot, and smoky--an appearance which attends +all similar periods more or less, refracting the red ray of the light, and +giving the sun a peculiar dry-weather, red appearance. (This smoky haze is +usually atmospheric, and occasionally seen even in March, although not +unfrequently fires in the woods fill the air with actual smoke, and very +much increase it, and when this is so, the odor of the smoke is often +perceptible.) Then we began to have a fresh south-west by south breeze in +the day-time, hauling to the south-west, and dying away at nightfall. The +next day, the tendency to condensation and consequent belt of showers +having extended further south and approached nearer to us, the S. S. W. +wind blew _fresher_ toward it, and _did not die away at nightfall_. During +the evening the reflection of the lightning playing upon the tops of the +thunder clouds, just visible at the north (heat-lightning, it is termed, +because supposed to be unaccompanied by thunder, but in reality lightning +reflected from clouds at too great a distance for the thunder to be +heard), and the continuance of the southerly wind after nightfall, gave +sure evidence of the coming showers the next day, and an end of the +excessive heat for that time. So ended both of those long-to-be-remembered +"heated terms" of 1853. + +The same is probably true of the interior of the country every where. +Lieutenant Maury, in the course of his investigations, and in order to +ascertain the direction of the winds in the Mississippi valley during +rain, addressed a number of gentlemen, and received their replies, which +are published with his wind and current charts. Several answered, among +other things, that, "whenever the lightning appears to linger at the north +at eventide, rain almost invariably follows speedily; not so in the +south." Thus it frequently is with us. If, during a hot, dry time, of a +few days continuance, the lightning so lingers in the evening, and the +wind continues to blow _fresh_ from the southward _after nightfall_, +showers will generally follow within forty-eight hours, most commonly the +next day, and a cool N. N. W. or N. W. wind with a favorable change ensue. +Such, at least, has been the result of my observation for many years. + +Indeed this seems to be the general law in summer in the Mississippi +valley, where the easterly winds are not so common as with us. To +illustrate this further, I copy from a recent work by T. Bassnett, +entitled the "Mechanical Theory of Storms," two short extracts, showing +the manner in which belts of showers extend southerly, while progressing +north-eastwardly, at Ottawa. The first occurred in August, 1853; the last, +December, 1852. The first was a belt of showers; the latter would have +been in August, but the lateness of the season changed its character +somewhat, though not entirely, to a more regular rain, especially toward +the close. + + "AUGUST 6th.--Very fine and clear all day: wind from S. W.; a light + breeze; 8 P.M. frequent flashes of lightning in the northern sky; 10 + P.M., a _low bank of dense clouds in north_, fringed with cirri, + visible during the flash of the lightning; 12 P.M., same continues. + + "7th.--very fine and clear morning; wind S. W. moderate; noon, clouds + accumulating in the northern half of the sky; _wind fresher_, _S. + W._; 3 P.M., a clap of thunder over head, and black cumuli in west, + north, and east; 4 P.M., much thunder and scattered showers; six + miles west rained very heavily; 6 P.M., the heavy clouds passing over + to the south; 10 P.M., clear again in north. + + "8th.--Clear all day; wind the same (S. W.); a hazy bank visible all + along on _southern horizon_. + + "DECEMBER 21st, 1852.--Wind N. E., fine weather. + + "22d.--Thick, hazy morning, wind east, much lighter in S. E. than in + N. W.; 8 A.M., a clear arch in S. E. getting more to south; noon, + _very black in W. N. W._; above, a broken layer of cirro-cumulus, the + sun visible sometimes through the waves; wind around to S. E., and + fresher; getting thicker all day; 10 P.M., _wind south, strong_; + thunder, lightning, and heavy rain all night, with strong squalls + from south. + + "23d.--Wind S. W., moderate, drizzly day; 10 P.M., wind west, and + getting clearer." + +It is obvious that the showers at the north passed east on the evening of +the 6th of August; that new showers, taking the same course, originated in +the north, but more southerly next day, with S. W. wind, and that they +passed east, and others formed successively further south, which passed +over the place of observation late in the afternoon, and that others +formed south and passed east during the night and next day, visible in a +bank on the southern horizon. + +Later or earlier in the spring and autumn, these brisk afternoon +southerly winds continuing after nightfall, indicate moderate rains from a +rainy belt extending in a similar manner, without the cumuli and thunder +which attend those of mid-summer. I shall recur to this class of showers +and storms when we come to their classification. + +Light surface winds from south-west to west are not often storm-winds, and +are usually those which the trade near the earth draws after it. Sometimes +the trade seems to draw the surface wind from the S. W. and W. S. W. with +considerable rapidity, and some scud a little distance above the earth. +When this is so, it will be found that a storm has passed to the north of +us, or a belt of rains is passing north, which may or may not have +sufficient southern extension to reach us. When there have been heavy +storms at the south in the spring, especially if of snow, the S. W. wind +which the trade draws after it, and which comes from the snowy or chilled +surface, is exceedingly "raw"--that is, damp and chilly, although not +thermometrically very cold. Probably every one has noticed these "_raw_" +S. W. winds of spring. + +Usually, when storms and showers, which have not a southern lateral +extension, pass off, the trade is very near the earth, and a light S. W. +wind or calm follows for a longer or shorter period. Not unfrequently, +however, our N. E. storms terminate with a S. W. wind, shifting suddenly, +perhaps, just at the close of the storm, during what is sometimes called a +"clearing-off-shower," or, more frequently, dying gradually away as a N. +E. wind, and coming out gently from the S. W., following the retreating +cloud of the storm. In such cases it is said to "clear off warm." + +With us the wind rarely blows from the west, except while slowly hauling +from some southerly point to the N. W. It is probably otherwise east of +the lakes and in some other localities to the north-west. + +Occasionally, and most frequently in March, a W. to W. N. W. wind follows +storms, and blows with considerable severity, with large irregular, +squally masses of scud, and sometimes a gale. Such was the character of +the dry gale which crossed the country, particularly Northern New York, in +March, 1854, doing great damage. These westerly winds are always +accompanied by a continued depression of the barometer, and peculiar, +foggy, scuddy, condensation, and should be distinguished with care from +the regular and peculiar N. W. wind, as they may be, by the continued +depression of the barometer, and the character of the scud. They are +doubtless magnetic storms. + +The remaining surface wind, the N. W., the genuine Boreas of our climate, +the invariable fair-weather wind, is one of great interest. It is unique +and peculiar. It is not the left-hand wind of a rotary gale, and has no +immediate connection with the storm. I have known it blow moderately, +fifteen successive days in winter; rising about ten A.M., and dying away +at nightfall. Occasionally, but very rarely indeed, a light wind exists +from the N. W. during a storm, owing probably to a focus of intensity in +relation to some surface the storm covers, like the focus which exhibits +itself as a clearing-off shower near the close of a storm; but the real +fair-weather Boreas is a different affair altogether. Let us observe with +care its peculiarities; they are instructive. + +1st. It rarely blows with any considerable force beneath the trade while +there are storm clouds, or any considerable condensation in it. It does +not interfere with that reciprocal action which takes place between the +trade and the earth, during approaching or existing storms. I have +frequently seen it with its peculiar scud clouds in the N. W., waiting for +the storm condensation of the trade to pass by, that full of positive +electricity it might commence its sports; rushing and eddying along the +surface, licking up the warm, south polar, electric rain, which stood in +pools upon the ground, or rose in steamy vapor from the surface, and with +its cool breath dry up the muddy roads as no degree of heat can dry them. + +The annexed figure (14) shows the appearance of the northern edge of a +stratus storm cloud, passing off E. N. E. at the close of the storm, which +was "_clearing off from the north-west_." It is from a daguerreotype view, +looking W. N. W., taken at eight o'clock in the morning, in the fall of +the year. Near the horizon maybe seen the N. W. scud, forming in the N. W. +wind, which is about to follow the retreating edge of the storm cloud. + +Figure 15 is from a daguerreotype view, taken at eleven o'clock the same +day, when the storm cloud had passed off and its edge remained visible +only south of the zenith, and the north-east scud had risen up and covered +the northern half of the sky, and the wind was blowing a gale from that +quarter. + + +[Illustration: Fig. 14.] + + +Another view was taken about two P.M. of the same day, when the scud had a +very dark, gloomy appearance--as _dark_ and _gloomy_ as those of a Mexican +norther--too dark to represent by a cut. + +Not unfrequently in a moist summer season, after a day of showers or rain, +which have had an extending formation or lateral extension from north to +south, it will commence blowing in the morning, and encourage the +hay-maker with the hope of fine weather. But often before noon, the milky +stratus condensation above with cumuli below, will appear in the trade; +the N. W. wind die away and variable airs from the east or south appear, +to be followed toward night by an enlargement of the cumuli and showers. +It rarely, if ever, blows fresh till the storm condensation of the trade +has passed; or continues to blow after that condensation reappears. When +it commences blowing after a storm, and the northern edge of the storm is +not over us, we may frequently see the latter low down in the S. E. +passing eastward. + + +[Illustration: Fig. 15. NORTH VIEW.] + + +2d. Its scud are peculiar. Every one, probably, has noticed them. They are +distinct, more or less disconnected, irregular, with every form between +those of the easterly scud, cumulus, and stratus, according to the season. +If large, with _dark under surfaces_; forming _rapidly_ and as _rapidly +dissolving_; rarely dropping any rain, sometimes dropping a flurry of +snow, in November or March, oftener than at any other period; sailing away +to the S. E., and casting a traveling shadow as they pass on over the +surface of the earth. Their electricity, particularly when white, is +probably always positive, as that of all whitish clouds is supposed to be. + +3d. _It is emphatically a surface wind._ The incident storm winds, the N. +E. and S. E., frequently _commence blowing_ under the storm, toward its +point of greatest intensity, _up near the line of cirro-stratus +condensation_, evidenced by the running scud; or blow there with most +rapidity, and so continue for hours before the whole surface atmosphere +from thence to the earth becomes involved in the movement; and sometimes +without being felt below at all. Not so with the N. W. wind; it _begins at +the surface_ and blows there with more rapidity than above; it seems to be +attracted by the earth; it interposes between the earth and the trade, +wedging the trade up and occupying its place. It blows under at all +seasons of the year, but most readily and strongly from a surface of snow +whose electricity is always positive. Hence it blows most strongly and +_continuously_ when snow has fallen at the north, and prevails during +winter very much in proportion to the extent and continuance of the +covering of snow which invests the earth in that direction. It follows +after storms, and particularly warm rains, during the autumn, winter, and +spring months, which have a lateral southern extension. Whether it is +increased by the snow from the surface from which it blows, or is caused +by the same magnetic action which causes the great fall of snow, is a +question we shall consider hereafter. + +4th. It does not connect or mingle with the trade current in any way, or +change or divert the course of that current; but interposes between it and +the earth, elevating the trade in proportion to its own volume, above the +influences of the earth (when the trade becomes free from condensation, +and singularly, clear); and raising _proportionately_ the barometer. An +experienced observer can frequently estimate, with considerable accuracy, +the rise of the barometer, by measuring with his eye, (when the clouds +will enable him to do so,) the depth of this interposed N. W. current. The +barometer rarely rises after a storm, for twenty-four or forty-eight hours +if the wind continues at any point from S. W. to W. N. W., but always +rapidly as soon as the genuine N. W. current with any considerable depth +interposes and elevates the trade. + +It will be obvious to every one, I think, certainly, if they will +hereafter study the subject and observe for themselves, that the N. W. +wind does not blow away the storm; and that it follows after it, blowing +over the surface which is uncovered by the storm; rarely, if ever, with +any force when the body of the storm passed south of us; and that it is a +purely surface wind, seemingly attracted by the peculiar magneto-electric +state in which the surface of the earth is left, compared with a snow-clad +surface to the north, by a recent storm, or that peculiar state of the +trade which is left by the action of the storm. It seems to follow that +magnetic wave which, passing from north to south, acts in its course upon +the counter-trade, producing the storm, or belt of showers, and giving +them their southern lateral extension, and will well repay future +telegraphic investigation. Its electricity is intensely positive--that of +the earth by the action of the storm as intensely negative. + +5th. This N. W. wind occurs in all parts of the northern hemisphere, so +far as we have data to determine, and its corresponding wind from the S. +W. occurs in the southern hemisphere. It is identical with a class of the +northers of the Gulf of Mexico, as a brief analysis of the character of +the latter will show. + +1st. The fall and winter _norther_ is a dry wind without rain or falling +weather--so is our N. W. wind. + +2d. It is preceded by a falling barometer; S. E. scud and rain at the +point where it blows, or to the eastward of it. So is ours when it blows a +gale in the fall and spring months, which bear the nearest resemblance in +climatic character to the periods when the northers blow. With this +distinction, however, that our precedent rains either pass over us or to +the southward, the direction of storms being E. N. E.; their precedent +storms passing over or to the eastward of them as they move more to the +northward. + +3d. It is often preceded by a copious dew; so is ours--such dews often +following light fall rains in our climate, and preceding N. W. wind. + +4th. The most peculiar characteristic, however, is that the barometer +rises rapidly and invariably while the norther prevails, and very much in +proportion to its violence. The same is true of our genuine N. W. wind, +and is not true _of any other wind_ on this continent which I have +observed or read of. + +5th. While they are thus alike in these respects, they are unlike in no +respect. + +Mr. Redfield has traced them in _supposed_ connection with storms which +continue from that vicinity across the United States to the E. N. E., and +endeavored to connect them with those storms, as the left-hand winds of a +rotary gale. Obviously, I think, they are identical with our N. W. winds +which also _follow_, indeed, but _are distinct from the storms_. + +There are a class of northers in the Gulf of Mexico--the "Nortes del Muero +Colorado"--sometimes occurring in the summer months, beginning at N. E., +veering about and settling at N. N. W., and as they decline hauling round +by the west to the southward. These winds correspond precisely with the +hurricane winds of the West Indies, and are doubtless the incident winds +of a storm traveling thence to the N. N. W. precisely as our N. E. or E. +N. E gales are incident storm winds to the N. E. storms of our latitude. + +In this connection we will look at the peculiarities of a West India +hurricane. + +"It is not a little remarkable," says Mr. Espy, speaking of the storms and +hurricanes of the West Indies, "that all these storms, and _all others +which have been traced to the West Indies_, traveled N. W. almost at right +angles to the direction of the trade-wind in those latitudes, but very +nearly, if not exactly, in the direction of an upper current of the air +known to exist there toward the N. W." Substantially the same facts have +been repeated by Mr. Redfield, and demonstrated by his able +investigations, both there and in the Eastern Pacific, and are confirmed +by the observations of Edwards, Lawson, and others, while residents there. +It is a matter of surprise that gentlemen like Messrs. Redfield and Espy, +who have certainly displayed great ability in the investigations of +meteorological phenomena, should fail to recognize a more intimate +relation between this upper current and the storms they were +investigating, and to detect the general laws which govern both. The +storms and hurricanes of the West Indies are comparatively of small +diameter, and have little advance condensation. When they pass on to the +south-western portion of North America and curve to the N. E., as they +frequently do, they enlarge in front and at the sides, and their advance +condensation, which is not dense enough to drop rain, extends in some +cases from one to three hundred miles; and the storm itself, by the time +it reaches the Alleghanies, may extend one thousand to fifteen hundred +miles, and perhaps in certain magnetic states of the surface, and +occasionally, may cover the entire portion of the continent, from north to +south. Such, probably, was very nearly the extension of the storm +investigated by Professor Loomis. In the West Indies, however, at the +commencement, they vary from twenty to one hundred miles, or possibly +more, in width. + +First, they are preceded by a hot, sultry and oppressive atmosphere--_as +are electric storms every where_--a peculiar electric state of the earth +and adjacent air. + +Second, the black clouds and lightning which indicate the approaching +hurricane are seen to the S., S. E., and E. S. E., according to the season +of the year, as we see them at the westward. During the rainy season, and +when the storm, as is usual at that period, is small, and the S. E. trade +blows more eastwardly, the wind at the Windward Islands, possibly, may set +in at the north, and back round by the east as it progresses. So Colonel +Reid thinks it sometimes does, at Barbadoes. But when the belt of rains is +south, and the hurricane comes from the south-east, and is larger and more +violent in its action, and the north-east winds prevail, the first effect +is an increase of these trades. Soon, however, the wind hauls to the north +and north-west, in opposition to its course, bearing the same relation to +it that our east and north-east winds bear to storms in the United States; +and the wind hauls around during the passage of the storm to the west, +south-west, and south-east, and at the latter point it clears off. Mr. +Edwards in his History of Jamaica says--and as a resident, his authority +should be decisive as to this Island--"_that all hurricanes begin from the +north_, veer back to the W. N. W., W., and S. S. W., and when they get +around to the S. E. the foul weather breaks up." Doubtless the same is +true of the class of northers of which we are speaking on the Gulf of +Mexico. _But with this class the barometer does not rise during the gale, +and in proportion to its length and violence._ With the other class of N. +W. winds--the northers of winter--it does. + +The following description of two winter northers, copied from Colonel +Reid's valuable work, will illustrate what has been said. _Precisely such +changes from S. E. rains to N. W. winds, with blue sky and detached dark +clouds--fair-weather N. W. scud--occur every autumn in October and +November_, and the falling of the thermometer and rising of the barometer, +after rain, and a change of the wind, are perfectly characteristic. + + ------------------------------------------------------------------------ + 1843. | Wind. |Force.|Weather.| Bar.|Ther.| + ------------------------------------------------------------------------ + Jan. 30.| | | | | | + A.M. 4. |S. S. W. | 2 |b. c. |29.90| 77 |Off Tampico. + Noon. |South. | 5 |b. c. r.|29.86| 76 | {Lat. 23° 41' N., + P.M. 8. |South. | 6 |b. c. r.|29.84| 76 | {Long. 94° 50' W. + Jan. 31.| | | | | | + A.M. 4. |S. Easterly.| 3 |b. c. |29.90| 74 | {Between 6 and 10 + | | | | | | {A.M., wind was + | | | | | | {variable. + Noon. |N. by W. | 9 |c. q. w.|29.96| 76 |Norther commenced at + | | | | | | 10 A. M. + P.M. 8. |N. N. W. | 9 |c. |30.09| 73 |Lat. 22° 36' N., + | | | | | | Long. 95° 48' W. + Feb. 1. | | | | | | + A.M. 4. |N. N. W. | 7 |c. g. |30.29| 63 |Lat. 22° 9' N., + | | | | | | Long. 94° 50' W. + Noon. |Westerly. | 6 |c. |30.30| 67 | + P.M. 8. |Calm. | 0 |c. |30.26| 67 | + ------------------------------------------------------------------------ + Feb. 14.| | | | | | + A.M. 4. |S. E. | 3 |b. c. r.|29.66| 73 |At Sacraficios. + Noon. |S. W. | 4 |b. c. |29.62| |Norther comc'd at 5.30 + | | | | | | P.M. + P.M. 8. |N. W. by N. | 10 |c. q. u.|29.72| 65 | + Feb. 15.| | | | | | + A.M. 4. |N. W. by N. | 10 |c. q. u.|30.10| 61 | {Gale moderated and + | | | | | | {again freshened + | | | | | | {about 8 A.M. + Noon. |N. W. by N. | 10 |c. g. q.|30.19| 61 | + P.M. 8. |N. W. | 4 |c. g. |30.20| 65 | + Feb. 16.| | | | | | + A.M. 4. |N. W. | 3 |q. |30.18| 62 | + P.M. 8. | N. N. W. | 2 | c. g. |30.21| 66 | + ------------------------------------------------------------------------ + + b. indicates blue sky--c. detached clouds--r. rain--v. visibility of + objects--q. squalls--w. wet dew--u. ugly threatening appearance--g. + gloomy weather. + +The exact counterpart of the first norther may be observed with us every +fall. On the 30th January, with a rising thermometer and falling +barometer, there was rain at midday. The night following was moist--the +next day, about ten A.M., the wind came out N. W., with squalls and gloomy +weather, a falling thermometer, and rising barometer. + +The norther of Feb. 14th differed from the other only in regard to the +time of the day when it commenced; the order of events was the same. The +rain fell in the night--it cleared off early in the day, and the norther +followed in the afternoon. This also is frequently the case with us, as +every one may observe. + +This brief notice of the surface winds of our climate would be incomplete +without a description of those of the thunder-gust and tornado. + +The former is exceedingly simple. The showers, which are accompanied with +much wind, form suddenly in hot weather, and have a considerable advance +condensation (frequently with obvious lateral internal action), extending +eastwardly from the line of smooth cloud from which the rain is falling, +or rather where the falling rain obscures the inequalities of the cloud. +_The gust is never felt until the advancing condensation has passed over +us_, when it takes the place of the gentle easterly breeze which +previously set toward the shower. _The gust ceases as soon as the cloud +has passed._ It is obviously the result of the inducing and attracting +influence of the cloud upon the atmosphere near the surface of the earth +as it passes over it. Let the reader watch attentively this advance +condensation, from its eastern edge to the line of smooth cloud and +falling rain, and he will understand at a glance this internal action of +gust-clouds. The whole phenomena are simple and intelligible. A cloud +approaching from a westerly point, dark and irregular from its eastern +edge to the line of falling rain, where it appears smooth and of a light +color; wind from the east blowing gently toward it, till the condensation +is over us; then the gust following the cloud; then the rain, and in a few +minutes the cloud, and wind, and rain have passed on to the east, and +"sunshine" returns. + +The tornado, as it is termed when it occurs upon land, "spout," if on the +water, is sometimes of a different character, and as it undoubtedly had +great influence in inducing the gyrating theory of Mr. Redfield, and the +aspiratory theory of Mr. Espy, and has been cited by both in support of +their respective theories, it deserves a more particular notice. There are +several marked peculiarities attending it which determine its character. + +1st. It occurs during a _peculiarly sultry and electric_ state of the +trade and surface atmosphere, and at a time when thunder showers are +prevailing in and around the locality, and at every period of the year +when such a state of the atmosphere exists. One recently occurred in +Brandon, Ohio, in midwinter. + +2d. There is always a cloud above, but very near the earth, between which +and the earth the tornado forms and rages. It is usually described as a +black cloud, ranging about 1000 feet or less above the earth, often with +a whitish shaped cone projecting from it, and forming a connection with +the earth; at intervals rising and breaking the connection, and again +descending and renewing it with devastating energy. Its width at the +surface varies from forty to one hundred and eighty rods--the most usual +width being from sixty to ninety rods. Sometimes when still wider, they +have more the character of thunder-gusts, and are brightly luminous. + +3d. Two motions are usually visible, one ascending one near the earth and +in the middle, and a gyratory one around the other. The latter is rarely +felt, or its effects observed, near the earth. Occasionally, and at +intervals, objects are thrown obliquely backward by it. + +4th. It is composed, at the surface of the earth, of _two lateral +currents_, a northerly and southerly one, varying in direction, but +normally at right angles in most cases, although not always, with its +course of progression, extending from the extreme limits of its track to +the axis; which currents are most distinctly defined toward the center, +and upward. These currents prostrate trees, or elevate and remove every +thing in their way which is detached and movable. There does not seem to +be any current in advance of these lateral ones tending toward the +tornado, save in rare and excepted cases, and then owing to the make of +the ground or the irregular action of the currents; nor any following, +except that made by the curving of the lateral currents toward the center +of the spout as it moves on, and perhaps a tendency of the air to follow +and supply the place of that which has been carried upward and forward, +like that of water following the stern of a vessel. The south current is +always the strongest, and often a little in advance of the other, and +covers the greatest area. The proportion of the two currents to each other +is much the same that the S. E. trades bear to the N. E. This excess in +volume and strength of the southerly current will explain the +irregularities in most cases, and the fact that objects are so often +_taken up and carried from the south to the north side_, and so rarely +from the north and carried south of the axis. These irregularities are +such as attend all violent forces, and something can be found which will +favor almost any theory; but the two lateral currents appear always to be +the principal actors, except, perhaps, when it widens out and assumes more +the character of a straightforward gust. See a collection by Professor +Loomis, American Journal of Science, vol. xliii. p. 278. + +The following diagram is a section of the New Haven tornado, from +Professor Olmstead's map accompanying his article in the "American Journal +of Science and Art," vol. 37. p. 340. + +The manner in which the main currents flow is shown by their early and +unresisted effect in a cornfield, as represented by the dotted lines. The +direction in which the fragments of buildings were carried by the greater +power of the southerly currents is shown also. And so is this irregular +action, where a part of the southerly current broke through the northerly +one, and prostrated two or three trees backward on the north side of the +axis. + + +[Illustration: Fig. 16.] + + +5th. This cloud, and its spout, move generally with the course of the +counter-trade in the locality--_i. e._, from some point between S. W. and +W., to the eastward, but occasionally a little south of east, deflected by +the magnetic wave beneath the belt of showers. + +6th. Several exceedingly instructive particulars have been observed and +recorded. + +_a_. _No wind is felt outside of the track_, as those assert who have +stood very near it, and its effects show. + +_b_. The track is often as distinctly marked, where it passed through a +wood, as if the grubbers had been there with their axes to open a path for +a rail-road. The branches of the trees, projecting within its limits, are +found twisted and broken off, or stripped of their leaves, while not a +leaf is disturbed at the distance of a foot or two on the opposite side of +the tree, and outside of the track. + +_c_. As the spout passes over water, the latter seems to _boil up_ and +_rise to meet it_, and _flow up_ its trunk in a _continued stream_. + +_d_. As it passes over the land, and over buildings, fences, and other +movable things, they appear to _shoot up_, instantaneously, as it were, +into the air, and into fragments. If buildings are not destroyed or +removed, the doors may be burst open _on the leeward side_, and gable ends +_snatched out_, and roofs taken off on the _same side_, while that portion +of the building which is to the windward remains unaffected. + +_e_. Articles of clothing, and other light articles, have been carried out +of buildings through open doors, or chimneys, or holes made in the roofs, +and to a great distance, without _any opening_ being made for the air to +_blow_ in. + +_f_. If there be a discharge of electricity up the spout from the earth, +like that of lightning, the intense action ceases for a time or entirely. + +_g_. Vegetation in the track is often scorched and killed, and so of the +leaves on one side of a tree, which is within the track, while those on +the other side, and without the track remain unaffected. (Espy's +Philosophy of Storms, 359, cited from Peltier.) + +_h_. The active agent whatever it is, has been known to _seize hold of a +chain attached to a plow_ and _draw the plow about, turning the stiff sod +for a considerable distance_. (See Loomis on the tornado at Stow, Ohio, +American Journal of Science, vol. xxxiii. p. 368.) + +_i_. In passing over ponds, the spout has taken up all the water and fish, +and scattered them in every direction, and to a great distance. + +_j_. The barometer falls very little during the passage of the spout. (See +the Natchez hurricane of 1827, Espy page 337.) Not more than it +_frequently_ does during gentle showers. + +_k_. Persons have been taken up, carried some distance, and if not +projected against some object in the way, or some object against them, +have usually been _set down gently and uninjured_. + +_l_. Buildings which stood upon posts, with a free passage for the air +under them, although in the path of the tornado, escaped undisturbed. +(Olmstead's account of the New Haven tornado, American Journal of Science, +vol. xxxvii. p 340.) + +_m_. A chisel taken from a chest of tools, and stuck fast in the wall of +the house. (Ibid.) + +_n_. Fowls have had all their feathers stripped from them in an instant +and run about naked but uninjured.[5] + +_o_. Articles of furniture, etc., have been found torn in pieces by +antagonistic forces. + +_p_. Frames taken from looking-glasses without breaking the glass. Nails +drawn from the roofs of houses without disturbing the tiles. + +_q_. Hinges taken from doors--_mud taken from the bed of a stream_ (the +water being first removed), and let down on a house covering it +completely--a farmer taken up from his wagon and carried thirty rods, his +horses carried an equal distance in another direction, _the harness +stripped from them_, and the wagon carried off also, _one wheel not found +at all_. (American Journal of Science, vol. xxxvii. p. 93.) + +Pieces of timber, boards, and clapboard, driven into the side of a hill, +_as no force of powder could drive them, etc., etc._ + +Now to my mind, these circumstances indicate clearly, that it is not wind, +_i. e._, mere currents of air, which produces the effect, but that a +_continuous current_ or _stream of electricity_ from the earth to the +cloud exists, and carries with it from near the earth, such articles as +are movable: That this stream collects from the _northerly_ and +_southerly_ side upon the _magnetic meridian_, in _two currents_ with +_polarity_, which meet in their passage up at the center; curving toward +the center in the posterior part as the spout moves on, when acting in a +normal manner, and making the "_law of curvature_" observed: That no +conceivable movement of the air alone in such limited spaces could produce +such effects; or if so, that no agent but electricity could so move the +air: That the air in a building could not shoot the roof upward, and into +fragments; much less could the air in a cellar by any conceivable force, +be made to elevate _or shoot up_ the entire house, and its inmates, and +contents--effects so totally unlike what takes place in gales, +hurricanes, and typhoons: That elastic free air never did nor could take +hold of the plow chain, and plow up the ground; or scorch and kill the +vegetation; or twist the _limbs_ from one side of a tree, while the most +delicate leaves on the other, and within two or three feet, remained +unaffected and undisturbed; or pick the chickens: That even if the +expansion of the air could produce these effects--if a sudden vacuum were +produced--_nothing but currents of electricity could produce the sudden +vacuum_, by removing the air above. + +It is well settled that atmospheric electricity can and does flow in +currents with light, by experiments in relation to the brush discharge, +etc. That it may do so without light or disruptive discharge, and in a +stream, or as it is termed, by convection, with the force and effect seen +in the tornado, is perfectly consistent with what we know of it--and it +is, I think clearly evinced that such is the character of the phenomena, +by the fact that a sudden powerful _disruptive_ discharge, _with light, up +the spout_, produces an instantaneous partial or total suspension of its +action; to be renewed as the cloud passes over _another_ and more highly +charged _portion_ of the _earth's surface_. Peltier gives instances where +the spout has been entirely and instantaneously destroyed by such a sudden +and powerful discharge of electricity; marking the spot where it was so +destroyed by a large hole in the earth, from which the discharge issued. +And in fact these tornados are often steadily luminous, and so much so, +when they occur in the night, as to enable persons to read without +difficulty. + +The lateral inward and upward currents, are accompanied, after they meet +and unite, or seem to unite, by gyratory or circular ones. How are they +produced? This question can only be answered by analogy. No permanent +impressions are left by the circular currents, except to a limited extent, +and in occasional instances; and observation of them has been, and must +necessarily be limited and uncertain. I have witnessed one or two on a +moderate scale; but owing to the suddenness of their passage, and the +confusion of the objects taken up, it was difficult to determine what the +circular currents were. When the southerly current is much the strongest, +it appears sometimes to cross the axis, and curve round the northerly one. +Perhaps this may be all the curving that really takes place, except at the +posterior part of the axis, for evidence of a curving on the south of the +axis is rarely, if ever seen. + +Assuming, however, that the main currents unite and form one from the +earth to the cloud, _induced_ circular currents would be in perfect +keeping with the known laws of electricity. Such currents, and with +magnetic properties, are always induced by powerful currents of voltaic +electricity passing through wires. And doubtless _in all cases_ powerful +currents of electricity _induce attendant circular currents_. This may +account for the external gyration of the spout. + +Or it may be that the two lateral currents of air which attend the +currents of electricity, do not unite; having opposite polarity, but pass +by and around each other, in connection with the circular magnetic +currents. Future observation and perhaps experimental research will +determine this. But it may not be accomplished by the present generation; +for the belief that tornados are mere whirlwinds, produced by the action +of the sun in heating the land, is adhered to, notwithstanding they cross +the intense magnetic area of Ohio in mid-winter, and seems to be +ineradicable. + +The proportions of different winds vary in different localities. For the +benefit of those who are curious, I copy a table from an able compilation +by Professor Coffin, published by the Smithsonian Institute, showing the +proportion of the winds at New Haven (the station nearest to me). It will +be noticed that during the year the N. W. winds blow the greatest number +of days; the S. W. next; the N. E. and S. E. less than either, and about +equal. It may be observed that the two latter bear about the same +proportion to the whole, that our number of cloudy and stormy days, +averaging about ninety, bear to the whole number of days in the year. + + +------------------------------------------------+ + |Course.| 1804. | 1811. | 1812. | 1813. | Total. | + |------------------------------------------------| + | N. | 143 | 105 | 90 | 111 | 449 | + | N. E. | 99 | 207 | 138 | 138 | 582 | + | E. | 33 | 18 | 22 | 23 | 96 | + | S. E. | 131 | 108 | 135 | 110 | 484 | + | S. | 58 | 69 | 113 | 80 | 320 | + | S. W. | 224 | 255 | 153 | 261 | 893 | + | W. | 81 | 69 | 102 | 57 | 309 | + | N. W. | 329 | 264 | 345 | 315 | 1253 | + +------------------------------------------------+ + +This work of Mr. Coffin has been brought to my notice since the foregoing +pages were written. The facts embodied in it will be found to comport with +what I have observed and stated. In relation to the proportionate number +of days in the year during which the wind blows from the different points +of the compass at the several stations it is very full and able. + +But it has cardinal defects. It does not show the _main currents_ of the +atmosphere. It treats the surface-winds, which are incidental, as +principals. The direction of the main currents is indeed shown frequently +by the mean course of the surface winds, but not uniformly or +intelligibly. Nor does it distinguish between the fair weather and storm +winds; nor always between the trade winds during their northern transit, +and the variable winds north of the trade-wind region. Hence, the +deductions derived from it disclose no general system, and sustain no +theory, although many very important facts appear. Some of these, +Professor Coffin found it difficult to reconcile with received theories, +or satisfactorily explain. For instance, he found the prevailing winds of +the United States, in Louisiana and Texas, S. and S. E.; in western +Arkansas, and Missouri, southerly, and in Iowa and Wisconsin, S. W., +forming a curve, and evidently connected together. + +Thus, alluding to the winds west of the Mississippi, and between the +parallels of 36° and 60°, he says: + + "On the American continent, west of the Mississippi, there appears to + be more diversity in the mean direction of the wind, yet here it is + westerly at sixteen stations out of twenty, from which observations + have been obtained. The most peculiar feature in this region, is the + _line_ of southerly winds on the western borders of Arkansas and + Missouri. It seems to form a connecting link between the winds of + this zone and the south-easterly ones that we find south of it; and, + in some degree, to favor an idea that has been advanced, that there + is a vast eddy, extending from the western shore of the Gulf of + Mexico, to the eastern shore of the Atlantic; that the easterly + trade-winds of the Atlantic Ocean, when they strike the American + continent, veer northwardly, and then N. E., and thus recross the + Atlantic, and follow down the coast of Portugal and Africa, till they + complete the circuit." + +This mean prevalence of the curving winds indicates the course of the +western portion of the concentrated counter-trade, of which we have so +fully spoken, and to which that portion owes its rains and fertility. +Doubtless the curve would have been traced somewhat further west, if +observations had been obtained from more westerly stations. + +The idea of an eddy, to which Professor Coffin alludes, is of course +unsound; that of a counter-trade, most fully confirmed; the curve +corresponding with that of the regular rains and fertility as they are +known to exist. + +Professor Coffin is a believer in the generally-received theory of +rarefaction, as the cause of all winds. His work is published by the +Smithsonian Institution, and the theory is, so far forth, nationalized. +But he found it very difficult to reconcile all the facts he obtained, +with the theory, and, possessing a truth-loving mind, he frankly admits +it. Alluding to the prevalence of N. E. winds off the coast of Africa in +the summer months, as shown by certain numbered wind-roses, he says: + + "Nos. 81, 83, 86, and 91, have caused me much perplexity. The arrows + for the warmer months evidently indicate a point of rarefaction + situated to the _south_ or _south-west_, and yet all the observations + from which they were computed were taken within a few hundred miles + of the African coast and desert of Sahara; a region, the annual range + of whose temperature must be exceedingly great. The only way in which + I can account for a fact so astonishing, is, by supposing the + deflecting forces at these numbers to be secondary to the influence + which we see so strongly marked in Nos. 88, 89, and 90. Let us, then, + first devote our attention to these." + +(We have not space for the map of Professor Coffin, nor is it necessary to +insert it. The numbers 81, 83, 86, and 91, refer to respective portions of +the Atlantic, west of Africa, North of the Cape de Verdes, of 5° of +latitude each, where the N. E. trades are drawing off from the coast. The +Nos. 88, 89, and 90 refer to like portions _below_ the Cape de Verde, +where the S. W. monsoons are found under the rainy belt; and the +explanation of the distinguished author is an attempt to account for the +blowing of the trades _from_ Sahara, by supposing them connected with the +monsoons further south, which seem to blow toward it.) + + "The intense heat of the Great Desert rarefies the air exceedingly + from June to October, inclusive, and hence the arrows of unparalleled + length (Plate XII.)," (showing the monsoon winds below the Cape de + Verdes,) "pointing toward it during those months, the longest being + longer than that which represents the most uniform of the + trade-winds, in the ratio of 104 to 89. The influence of this + rarefaction is sufficient to curve the powerful current of the + trade-winds in the manner exhibited on Plate VII. Nos. 89 and 90, and + to produce the not less remarkable change in No. 88, holding the + current back and retarding it, so that its progressive motion in the + _three_ months of July, August, and September united, hardly exceeds + that during any _one_ of the colder months of the year. But while + this is so, the trades on the western side of the Atlantic are + pursuing nearly their regular track, being but slightly affected by + these influences. As a consequence, the latter must leave, as it + were, a partial vacuum behind them, which is filled by air flowing in + from the north-east and south-east. This will account for the seeming + anomaly of having a somewhat strong deflecting force directed toward + mid-ocean, in the hottest part of the year, as in the numbers above + referred to. _And yet it may be very naturally asked, Why does not + the air from these parts supply the Great Desert directly, instead of + taking a circuitous route to supply the region that supplies it? A + question which, I confess, it seems difficult to answer._" + +(The italicization in the foregoing extract is mine). + +Here the worthy professor finds a fact inconsistent with the theory of +rarefaction--viz.: that the winds blow off shore, and toward mid-ocean, +opposite Sahara, and he is "perplexed and astonished." The theory, +however, must be maintained, and one of those modifying hypotheses which +have made meteorology such a complicated piece of patch-work, must be +invented; some "deflecting forces" found. There is the Great Desert, +bordering upon the ocean, north of the Cape de Verde Islands, for a +distance of six hundred miles, widening as it extends inland, whose +temperature, as he says, "_must be exceedingly great_;" and doubtless is +so, and yet the air, instead of blowing in upon it in a hurricane, is +actually drawing off from it, and blowing towards the S. W., where the +water and air do not rise above 84°. Well may he be "perplexed and +astonished." + +Turning south, however, to the distance of five hundred miles or more, he +finds the S. W. monsoon winds, which in those months blow under the belt +of rains, toward the land, in the direction of, but at a great distance +from, Sahara. It is an easy matter to suppose that they reach the Great +Desert and supply its vortex of rarefaction, inasmuch as they blow in a +direction toward it, and distance is no impediment to supposition. + +Then it is necessary to _suppose_ that the S. E. and N. E. trades, at the +south-west, draw so strongly to the westward as to create a partial vacuum +to the S. W. of Sahara, which is filled by the winds which draw off shore, +and then we have the supply brought from the distance of five hundred +miles or more, by an ascending vortex, which creates a vacuum, and the air +near the vortex taken away in _another_ direction by a _partial_ vacuum; +and so an ascending _vortex_, which creates a vacuum is supplied from a +distance, and a _partial vacuum_ at a distance is supplied by the air near +the perfect vacuum. Such an idea of a supply by a circuitous route, and +secondary influence, is not very philosophical, to say the least, and +Professor Coffin feels it; and to the question, Why is it so? which, he +says, may very naturally be asked, he confesses there is no answer. And +there would be none, even if his suppositions were based upon facts. But +other questions might be asked equally difficult to be answered, viz.: + +1st. Is there any rarefaction which can draw the trades to the west, and +in that particular locality, in opposition to the supposed vortex of +Sahara, by creating a _partial vacuum_? + +2d. Are they in fact so drawn? + +3d. Do the S. W. winds, south of the Cape de Verdes, and _under the rainy +belt_, which in the summer months extend up to these islands, _reach the +desert at all_? + +These are pertinent questions, _and every one of them must be answered in +the negative_. The hypothesis is without foundation, and Professor's +Coffin's perplexity and astonishment must remain, until he abandons the +theory of rarefaction entirely. The winds which so perplex him are nothing +but the regular N. E. trades, made to originate on the coast and continent +of Africa, in summer, by the northern transit of the whole machinery. They +not only draw off from the desert coast, but they _blow over the desert +itself_ on to the ocean, and into the rainy belt upon the land, as we have +already seen, and the supposed vortex of rarefaction does not exist. + +That the monsoons do not reach the desert is demonstrated by the tables of +Professor Coffin, and to set it at rest we will make the necessary +extracts. Commencing with the region from the equator to 5° N., and from +10° to 55° W. longitude, we have the observed winds in proportion, as +follows, for July and August--the south-east trades prevailing, inasmuch +as the belt of rains is at this season situated further north. + +LATITUDE 0° TO 5°, LONGITUDE FROM GREENWICH 10° TO 55°. + + +-------------------------------------------------------+ + | Course. | July. | August. | Course. | July. | August. | + |-------------------------------------------------------| + | North. | 0 | 0 | S. S. W.| 54 | 111 | + | N. N. E.| 8 | 2 | S. W. | 1 | 29 | + | N. E. | 6 | 2 | W. S. W.| 6 | 19 | + | E. N. E.| 27 | 16 | West. | 2 | 9 | + | East. | 31 | 20 | W. N. W.| 1 | 6 | + | E. S. E.| 120 | 96 | N. W. | 1 | 0 | + | S. E. | 216 | 276 | N. N. W.| 0 | 2 | + | S. S. E.| 218 | 443 | Calm. | 8 | 4 | + | South. | 69 | 279 |---------------------------| + | | | | Total | 768 | 1,314 | + +-------------------------------------------------------+ + +Here, it is evident that the S. E. trades are the prevailing winds, but +their course is variable. + +Ascending to the region between 5° and 10° north latitude, and 10° to 55° +west longitude, the northern part of which at this season is covered by +the rainy belt; we find the monsoon, the S., S. S. W., and S. W. winds, +the prevailing ones in August, although the winds are variable, as usual +under the rainy belt. + + +-------------------------------------------------------+ + | Course. | July. | August. | Course. | July. | August. | + |-------------------------------------------------------| + | North. | 19 | 6 | S. S. W.| 188 | 368 | + | N. N. E.| 26 | 11 | S. W. | 63 | 94 | + | N. E. | 104 | 32 | W. S. W.| 73 | 93 | + | E. N. E.| 30 | 16 | West. | 33 | 48 | + | East. | 45 | 29 | W. N. W.| 30 | 18 | + | E. S. E.| 36 | 40 | N. W. | 21 | 9 | + | S. E. | 93 | 53 | N. N. W.| 17 | 13 | + | S. S. E.| 225 | 307 | Calm. | 109 | 74 | + | South. | 239 | 514 |---------|-------|---------| + | | | | Total | 1,351 | 1,725 | + +-------------------------------------------------------+ + +Ascending to the region of 10° to 15° north latitude, and 15° to 45° west +longitude, we find the winds exceedingly variable, and the monsoons +diminished remarkably. If Professor Coffin's theory was correct, they +should increase as they approach the desert; but they in fact, diminish, +and the N. E. trades are found at the north portion. + + +-------------------------------------------------------+ + | Course. | July. | August. | Course. | July. | August. | + |-------------------------------------------------------| + | North. | 17 | 55 | S. S. W.| 30 | 71 | + | N. N. E.| 64 | 74 | S. W. | 33 | 63 | + | N. E. | 155 | 149 | W. S. W.| 19 | 43 | + | E. N. E.| 91 | 71 | West. | 12 | 25 | + | East. | 83 | 60 | W. N. W.| 17 | 21 | + | E. S. E.| 25 | 26 | N. W. | 13 | 24 | + | S. E. | 17 | 26 | N. N. W.| 24 | 56 | + | S. S. E.| 13 | 33 | Calm. | 62 | 78 | + | South. | 9 | 44 |---------|-------|---------| + | | | | Total | 684 | 919 | + +-------------------------------------------------------+ + +Ascending to the region between 15° and 20° north latitude, and 15° to 45° +west longitude, we get north of the belt of rains _and lose the monsoons +entirely although still below the desert_; and find the regular N. E. +trades, with less variable winds than are found in almost any other part +of the ocean. + + +-------------------------------------------------------+ + | Course. | July. | August. | Course. | July. | August. | + |-------------------------------------------------------| + | North. | 39 | 20 | S. S. W.| 0 | 5 | + | N. N. E.| 210 | 185 | S. W. | 0 | 5 | + | N. E. | 112 | 87 | W. S. W.| 8 | 3 | + | E. N. E.| 114 | 104 | West. | 0 | 1 | + | East. | 20 | 36 | W. N. W.| 0 | 4 | + | E. S. E.| 21 | 17 | N. W. | 3 | 4 | + | S. E. | 0 | 2 | N. N. W.| 3 | 31 | + | S. S. E.| 2 | 11 | Calm | 20 | 8 | + | South. | 5 | 1 |---------|-------|---------| + | | | | Total, | 557 | 526 | + +-------------------------------------------------------+ + +Ascending still further to the region between 20° and 25° north latitude, +and 15° and 45° west longitude, which borders, in part, on the S. W. +corner of the desert, and we have not, during the month of August, a +single wind between S. S. E. and W. N. W., which blows in upon the land; +and _only twelve instances out of three hundred and ninety-four in this +hottest month in the year, and on the southern portion of the desert, when +the wind blows on shore from any quarter_. This is demonstration. The +monsoon winds are confined to the rainy belt; they do not reach the +desert, nor does the desert attract the winds from the ocean, or +reverse, hold back, or disturb the trades. + + +-------------------------------------------------------+ + | Course. | July. | August. | Course. | July. | August. | + |-------------------------------------------------------| + | North. | 25 | 20 | S. S. W.| 3 | 0 | + | N. N. E.| 210 | 153 | S. W. | 2 | 0 | + | N. E. | 129 | 77 | W. S. W.| 13 | 0 | + | E. N. E.| 110 | 86 | West. | 0 | 0 | + | East. | 8 | 20 | W. N. W.| 0 | 3 | + | E. S. E.| 4 | 11 | N. W. | 2 | 1 | + | S. E. | 0 | 3 | N. N. W.| 5 | 8 | + | S. S. E.| 1 | 7 | Calm. | 2 | 5 | + | South. | 1 | 0 |---------|-------|---------| + | | | | Total, | 515 | 394 | + +-------------------------------------------------------+ + +Ascending once more, to the region between the degrees of 25 and 30, north +latitude, and 15 and 45, west longitude, we find it bounded east entirely +on the center of the desert. Now here, certainly, there must be evidence +of the truth of the rarefaction theory, if any where on the face of the +earth. Yet here, in July and August, we find the trades as regular as any +where, and not more variable winds than are found in the trades toward +their northern limits every where, and in August, only forty out of four +hundred and twenty-nine winds, blowing directly or indirectly on shore. + + +-------------------------------------------------------+ + | Course. | July. | August. | Course. | July. | August. | + |-------------------------------------------------------| + | North. | 32 | 19 | S. S. W.| 9 | 6 | + | N. N. E.| 155 | 125 | S. W. | 3 | 9 | + | N. E. | 144 | 35 | W. S. W.| 13 | 14 | + | E. N. E.| 140 | 89 | West. | 12 | 3 | + | East. | 48 | 57 | W. N. W.| 7 | 7 | + | E. S. E.| 31 | 23 | N. W. | 11 | 1 | + | S. E. | 8 | 7 | N. N. W.| 36 | 6 | + | S. S. E.| 8 | 12 | Calm. | 18 | 12 | + | South. | 5 | 4 |---------|-------|---------| + | | | | Total, | 680 | 429 | + +-------------------------------------------------------+ + +It would seem to be impossible for any man to believe in the theory of +rarefaction, after an examination of these tables. + +Professor Coffin discovers other anomalies, for which he finds it +difficult to account. Among these are the northerly tendency, in the +afternoon, of the winds in Ohio, south of Lake Erie; the winds of +south-western Asia, which, he says, "Are so irregular as to defy all +attempts to reduce them to system;" particularizing the N. W. at +Jerusalem, the westerly at Bagdad, the N. E. at Constantinople, the +northerly at Trebizond, etc., etc. Jerusalem has the Mediterranean at the +N. W., Bagdad has it at the west, Constantinople has the Black Sea at the +N. E., Trebizond N. N. W. and N. E., and the counter-trade, as it passes +over them, draws its storm-surface wind or sea-breeze, from the quarter +where evaporation is greatest, and the atmosphere is most susceptible of +electrical inductive influence. Precisely as it draws from the ocean and +the eastward, east of the Alleghanies, from the lake region, west of the +lakes, and from the northward, south of the lakes, and from the westward, +east of them. + +This law of attraction will explain, too, the mean prevalence of easterly +winds north of the parallel of 60°, at the stations named in his work. +Great Bear Lake, Great Slave Lake, and Fort Enterprise, lie east of the +Rocky Mountain range which interposes between them and the Pacific, and +have Hudson's Bay and other large bodies of water on the east and north. +Hence, easterly winds prevail at these places. At Norway House, on +Nelson's River, near the north end of Lake Winnipeg, a large body of +water, which stretches off to the south, we find the south wind the +prevalent one, especially in December, when the northern and north-eastern +waters are frozen up, and the N. E. largely present at all seasons of the +year. + +At New Hernhut, in winter, when Davis' Straits are covered with floes, the +prevailing wind is east, drawn from the warm, open sea east of Greenland, +where the Gulf Stream is evaporating. But in June and July, when +evaporation is going on over Davis' Straits and Baffin's Bay, the +prevailing winds are west and south, and the east winds fall off. + +Other stations are equally instructive, but I must forbear. + +In relation, however, to the easterly zone of wind, of which Professor +Coffin speaks, it should be added that the counter-trade, south of the +magnetic pole, in high latitudes, pursues an easterly course, is near the +earth, and attracts an opposite wind as it does on the east and north of +the pole, in localities where the surface atmosphere is not peculiarly +susceptible to its influence, and, therefore, the _winds are mainly +opposite to its course_. Thus, at Melville Island, they are almost all +westerly and north-westerly, for there the remnant of the counter-trade is +passing west around the magnetic pole. These westerly and north-westerly +winds are very light, and like the gentle easterly breeze which sets +toward the cumulus clouds and summer showers. + +Since most of this work was written, I have procured, and read with great +pleasure, Lieutenant Maury's "Geography of the Sea." It is a work of +great interest, and should be in the hands of every one. The extent of +ground covered, however, made it necessary for Lieutenant Maury to +introduce much matter not derived from his own investigations. In doing +this, he has taken received opinions, and has thereby introduced much +heresy. The view he adopts in relation to the monsoons, although the +popular one with philosophers, is of that character. He says (page 222): + + "Monsoons are, for the most part, formed of trade-winds. When a + trade-wind is turned back, or diverted, by over-heated districts, + from its regular course at stated seasons of the year, it is regarded + as a monsoon. Thus, the African monsoons of the Atlantic, the + monsoons of the Gulf of Mexico, and the Central American monsoons of + the Pacific, are, for the most part, formed of the north-east + trade-winds, which are turned back to restore the equilibrium which + the over-heated plains of Africa, Utah, Texas, and New Mexico have + disturbed. When the monsoons prevail for five months at a time--for + it takes about a month for them to change and become settled--then + both they and the trade-winds, of which they are formed, are called + monsoons." + +Again (§ 476-7): + + "The agents which produce monsoons reside on the land. These winds + are caused by the rarefaction of the air over large districts of + country situated on the polar edge, or near the polar edge, of the + trade-winds. Thus, the monsoons of the Indian Ocean are caused by the + intense heat which the rays of a cloudless sun produce, during the + summer time, upon the Desert of Cobi and the burning plains of + Central Asia. When the sun is north of the equator, the force of his + rays, beating down upon these wide and thirsty plains, is such as to + cause the vast superincumbent body of air to expand and ascend. There + is, consequently, a rush of air, especially from toward the equator, + to restore the equilibrium; and, in this case, the force which tends + to draw the north-east trade-winds back becomes greater than the + force which is acting to propel them forward. Consequently, they obey + the stronger power, turn back, and become the famous south-west + monsoons of the Indian Ocean, which blow from May to September + inclusive. + + "Of course, the vast plains of Asia are not brought up to monsoon + heat _per saltum_, or in a day. They require time both to be heated + up to this point and to be cooled down again. Hence, there is a + conflict for a few weeks about the change of the monsoon, when + neither the trade wind nor the monsoon force has fairly lost or + gained the ascendency. This debatable period amounts to about a month + at each change. So that the monsoons of the Indian Ocean prevail + really for about five months each way, viz.: from May to September, + from the south-west, in obedience to the influence of the over-heated + plains, and from November to March inclusive from the north-east, in + obedience to the trade-wind force." + +What the "trade-wind force" is, Lieutenant Maury tells us in another +paragraph, viz.: "Calorific action of the sun and diurnal rotation of the +earth"--the received calorific theory. I have already shown, I think, +conclusively, that there is no expansion and ascent in the supposed region +of calms, which induces, or can induce, the trades; and that, in point of +fact, the air on the land is cooler under the belt of rains. But as +Lieutenant Maury, whose reputation is national, adopts the theory, I shall +be pardoned for copying the following table, showing the difference of +temperature at two cities of India, before, after, and while the belt of +inter-tropical rains is over them. It will be seen that the temperature is +actually less when the belt is there, viz., in July and August, than in +April and May. _This should be conclusive upon that point._ + + +----------------------------------------------------+ + | | Anjarakandy. | Calcutta. | + | Months. |--------------------|-------------------| + | | Rain. | Temp. | Rain. | Temp. | + |-----------|----------|---------|---------|---------| + | | M. M. | | M. M.| | + | January, | 2,26 | 26°,5 | 0,0 | 18°,4 | + | February, | 2,26 | 27°,7 | 67,68 | 21°,5 | + | March, | 6,77 | 28°,4 | 24,82 | 25°,6 | + | April, | 29,33 | 29°,8 | 130,84 | 28°,5 | + | May, | 175,96 | 28°,6 | 16,24 | 29°,7 | + | June, | 794,05 | 26°,6 | 575,24 | 29°,3 | + | July, | 807,59 | 25°,8 | 338,38 | 28,°1 | + | August, | 572,98 | 26°,0 | 311,31 | 28°,3 | + | September,| 311,31 | 26°,4 | 254,91 | 28°,0 | + | October, | 157,91 | 26°,8 | 42,86 | 27°,2 | + | November, | 65,42 | 26°,9 | 20,30 | 23°,0 | + | December, | 29,33 | 26°,5 | 0,0 | 19°,2 | + |-----------|----------|---------|---------|---------| + | Year, | 2955,14 | 27°,2 | 1928,74 | 26°,4 | + +----------------------------------------------------+ + +Anjarakandy is on the Malabar coast, between 12° and 13° north latitude. +Calcutta in an angle of the Bay of Bengal, at 22° 30' north latitude. The +former is in and near the focus of the monsoons, and has a temperature in +July (when 18 inches of rain fall), about as low as in December. + +In the foregoing table from Kaemptz, the rain is in millimetres, about +twenty-five of which make an inch, and the temperature is centigrade, +which may be raised to Fahrenheit by adding four fifths of the quantity +and also 32°--thus, if the height of the centigrade thermometer be 25°, +add to this four fifths of 25°, which is 20°, and also 32°, the result is +77°. Twenty-five centigrade is therefore equal to seventy-seven +Fahrenheit. + +Lieutenant Maury is not, and should not be a theorist. He occupies the +position, in some sort, of a national _investigator_, and, of course, of +national _instructor_. Opinions which emanate from him, or which are +endorsed by him, should be accurate. Sooner or later that which he has +adopted in relation to the monsoons, and some others, must be abandoned. +In addition to what has already been said, I wish to call his, and the +reader's attention, to several other facts and considerations in relation +to the monsoons, and particularly those of India. + +1st. The deserts of Cobi and Bucharia, which constitute the "burning +plains" of _Central_ Asia, north-east of the Indian Ocean, lie between 38° +and 45° of north latitude, and under the zone of extra-tropical rains. +They are not wholly rainless. They partake of that saline character which +affects so much of Asia and the western part of this continent. South of +them, running nearly east and west, are the lofty ranges of the Himmalaya +and Kuenlun Mountains, and the table lands of Thibet. To their saline +character, in part, but mainly to the interposition of these mountain +ranges, depriving the counter-trade of moisture, they owe their +comparative sterility. _If bountifully supplied with rains, this salt +would doubtless ere this have been washed to the ocean, as it has been +from other countries, once as salt as they._ But they have some rain, and +more or less vegetation, and are not intensely hot. They lie too far +north, and are too elevated. Their temperature is not materially different +from that of the western, and comparatively desert portions of our own +country, and they are utterly incapable of creating a monsoon at the +Indian Ocean, and especially from the long line of Malabar coast, where +the south-west monsoons are found in most strength. The sterile portions +of Utah, New Mexico, and Texas are alike incapable of such effect upon the +atmosphere of Central America and Mexico. These monsoons commence in May, +and prevail until October, and the temperature of the air where they blow +ranges with considerable regularity between 76° at night, and 84° at +mid-day, on the Malabar coast, and a trifle lower in Central America. + + At Fort Fillmore, El Paso, New Mexico, in latitude 32°03, the mean + temperature for + + May is 68° + June " 78°, 5' + July " 80°, 1' + August " 83°, 8' + September " 77°, 9' + ------- + And for the whole period, 77°, 1' + + At Santa Fé, New Mexico, the mean for + May is 66°, 9' + June " 72°, 5' + July " 75°, 3' + August " 72°, 9' + September " 62°, 3' + ------- + And for the whole period, 69°, 3' + + Mean of the two united, 73°, 2' + +The mean of Western Texas is about 2° higher than at Fort Fillmore, and of +Utah not materially different; and the mean of _Central_ Asia between 38° +and 45° does not materially vary from them. + +Now, it is perfectly evident that during May and September the temperature +of Central Asia is far below that of the Indian Ocean and India, and never +materially exceeds it. Central Asia is hot, "burning," if you please, +compared with more elevated, fertile, or better watered territory _in the +same latitude_, and so it has been characterized; but not so, compared +with the Indian Ocean, or India, where the sun is vertical. During the +greater part of the time, therefore, that the monsoons are in full blast, +Utah, Texas, and New Mexico, and Cobi, and the burning plains of Asia, are +from 5° to 10° colder than the temperature of the place where the monsoons +are blowing. Would not such a fact be perfectly conclusive in any other +science except theory-swathed meteorology? + +2d. The theory assumes that the heated air has an ascensive force, which +causes it to rise and create a vacuum, and this vacuum, by its suction, +draws in the adjoining air, which immediately ascends. The adjoining air, +drawn away from its locality, leaves a vacuum, and that is filled by +another rush from the S. W., and so on, till the Indian Ocean is reached, +and the monsoons are accounted for. + +Now, look at the difficulties: + +The highest temperature that can be assumed for the air over Cobi, at any +time, without disregarding facts and analogy, is 100°. What is the +ascensive power of an area of atmosphere of 100°? For this we have no +problem or formula, although problems and formulas abound in the science. +Professor Espy relied on heated air only to give the storm a _start_. His +main reliance was on the latent heat supposed to be given out during +condensation, for his ascensive storm power. But over these "burning +plains" there is, according to the theory, no storm or cloud, or +condensation on which that supposed reliance for expansion can be placed. +What, then, is the ascension force of air at 100°? _We ought to know, for +we sometimes have it as high, or within two or three degrees as high, in +all the eastern and middle States._ + +The monsoons blow at from twenty to twenty-five miles an hour, and +sometimes more. Is that the ascensive force of air at 100°? At 25 miles an +hour it would be 2,200 feet; at 20 miles, 1,760 feet; and at 10 miles, 880 +feet per minute. + +Does any man believe that either current exists? Why, then, do we not have +our hats taken off, or light objects carried up, or have a monsoon, or, at +least, have the clouds running up, when we have such elevated +temperatures. _Nothing of the kind occurs with us._ Our hottest days are +comparatively still days; and I have seen the cumulus sailing gently to +the east, horizontally, when the air was at 98°. Why should we be exempt? +Is not our air the same and our heat the same? + +Again, suppose we grant that the ascensive force is equal to 20 or even 10 +miles an hour, will not the adjoining air hold back somewhat to avoid +leaving behind an entire vacuum? or, will it all voluntarily rush in, and +leave a new complete vacuum? and, if so, why the preference of vacuums by +the air, and _when, where, and why_, should the _successive vacuums stop_? +Nay, would not gravity fill the second vacuum from _above_, rather than +from the south-west side? and will not the air incline to rush in, to some +or all these successive vacuums, from some other side than south-west? or, +have these deserts the power of selecting the quarter from which their +vacuum shall be filled, and of delegating it to succeeding vacuums? Would +it not incline to rush in from the east and west where there are no +elevations, rather than from the S. W. and over the Kuenlun Mountains, the +intervening ridges and valleys of Thibet, the lofty Himmalayas, the extent +of India, and the Ghaut Mountains, from three to four thousand feet high, +on its eastern coast? Would it not, at least, _leak in a little_, and +lessen the force with which the vacuums would draw from the far-off Indian +Ocean, so that the monsoon could not blow with equal force? or, if Cobi +and its fellow deserts _must_ and _can_ draw from an _ocean_, why not from +the head of the Arabian Sea, or Bay of Bengal, or the China Sea, which are +nearer, or from the Japan Sea, which is still nearer, or the Yellow Sea, +which is close by? Why draw only from under the central belt of rains? +Nay, what shall be done with Professor Dove? In a recent article, +republished in the American Journal of Science and Art, for January, 1855, +he says: "A greatly diminished atmospheric pressure taking place in summer +over the _whole continent_ of Asia must produce an influx from all +surrounding parts; and thus we have west winds in Europe, north winds in +the Icy Sea, east winds on the east coast of Asia, and south winds in +India. _The monsoon itself becomes, as we see, in this point of view, only +a secondary phenomena._" This looks very like _antagonism_. Who shall we +believe? + +Again, suppose you get one atmosphere from the whole area, raised up by +the supposed ascensive force, and at the rate of twenty-five, twenty, or +even ten miles an hour, and a new volume drawn in from the south-west, +and _over the mountains_: will it not take a _little time_ for _that_ to +_heat up_? Does it heat so fast as to _keep up the ascensive force_ +without intermission, at twenty-five, or twenty, or ten miles the hour? +What says Mr. Ericsson to this? Can he not arrange with a moderate lens, +to move his engine with the rays of the summer sun? Nay, Lieutenant Maury +says they can not heat up "_per saltum_, or in a day." But according to a +reasonable calculation, they must heat up the air from 80°, or less, to +100°, at the rate of 2,000 feet per minute. Heating 2,000 feet in depth, +in the proportion of 20° per minute, night and day, for five months, is +"_per saltum_" in a minute, and 1,440 "_saltums_" per day! + +And further still, the Indian Ocean, from which the monsoons are drawn to +Cobi and Central Asia to the N. E., is during those months covered by the +belt of calms and rains, as heretofore stated; and the S. E. trades +blowing into it are attributed to the suction created by the ascent of +heated air _there_. So, then, the monsoons are blowing away from under the +rainy belt, from 500 to 1000 miles, to Cobi and the burning plains of +Asia, while the ascensive force of that belt is such as to draw the S. E. +trades toward the very spot, a distance of 1,200 or 1,500 miles, at 20 +miles an hour! What must the ascensive force over Cobi, etc., be, if, as a +"stronger power," it can overcome an ascensive force over the Indian Ocean +sufficient to draw the S. E. trades 1,500 miles, at 20 miles an hour; and, +in addition to the force necessary to resist this central suction, not +only stop or hold back the N. E. trade, but reverse it and draw it back, +at 20 miles an hour, as a monsoon? Must it not be, at least, double that +of the belt of calms, or the "great region of expansion," as Professor +Dove calls it? + +Now, I am irresistibly tempted to ask whether a meteorological theory can +be too absurd for credence, and whether it would not be as well to endow +the deserts with ribs and lungs, and a proboscis long enough to reach the +Indian Ocean, and the necessary power of inspiration and expiration? Such +a theory would avoid all difficulties, conflict with no more analogies, +and, in my judgment, be as much entitled to credit as the one to which +meteorologists adhere. + +3d. North of the Malabar coast, in the north-west of India, lies an +extensive desert. West of that is Beloochistan, with its rainless deserts. +Further west are the rainless deserts of Arabia, and these three, +including the Persian deserts further north, cover _as much surface_ as +the deserts of Cobi and Bucharia--have the sun vertical in part, and +nearly so over the entire surface--_are more intensely hot_, and lie +within _one third of the distance_ which intervenes between that desert +and the Indian Ocean off the Malabar coast, with _an open sea and_ no +_mountains between_. Now, look at it. The north-west desert of India, and +the rainless deserts of Beloochistan and Arabia _reverse no trade_ and +_have no monsoon_, although the Arabian Sea heads right up among them. +They do not attract one from the Indian Ocean off the Malabar coast, +although not more than one third of the distance off, and without such +mountains and table lands intervening as separate that coast from Cobi. It +is said by Lieutenant Maury that the monsoons, "_obey the stronger +force_." But which is the stronger force? Cobi, not _wholly_ rainless, +lying north of 35°, under the zone of extra-tropical rains, with India and +the Ghauts, the Himmalaya Mountains, the table lands of Thibet, and the +Kuenlun Mountains between? or the deserts of India, Beloochistan, and +Arabia, _wholly rainless_, and _intensely hot, near by_, and in _open +view_. There can be but one answer to this question. Nothing in the way of +desert barrenness, or elevated temperature, unless it be those of Sahara, +can exceed the deserts about the head of the Arabian Sea and Persian Gulf. +Certainly those of Cobi can not compare with them; yet the trades blow +steadily over them, although more northerly there, as every where, near +their northern limits, especially on land. Says Hopkins, in his +atmospheric changes: + + "If any one part of the broad expanse of the continent of Asia could + be heated so as to draw air from the Arabian Sea and the Indian Ocean + during the summer, it would be that part which lies between + Hindoostan and the Lake of Aral, including the region between the + Valley of the Oxus and Persia, and the land of this part, unlike + Hindoostan, is not screened from the sun by thick vapors. But what + says Burnes respecting the winds of this part? Why, that about the + latter end of June, though the thermometer was at 103° in the day, + 'In this country a steady wind generally blows from the north.' And + on the 23d of August, after having passed the Oxus--'The heat of the + sand rose to 150°, and that of the atmosphere exceeded 100°, but the + wind blew steadily, nor do I believe that it would be possible to + traverse this tract in summer if it ceased to blow. The steady manner + in which it comes from one direction is remarkable in this inland + country.' Again--'The air itself was not disturbed but by the usual + north wind that blows steadily in this desert.' And he has many other + similar passages." + +Here there is a vast tract of country south of 35° which has a temperature +often of 103°, and does not reverse the trade and create a monsoon. How +utterly unphilosophical, then, to attribute the monsoons to Cobi because +they "obey the stronger force!" or to attribute them to it at all. + +4th. The monsoons can not be _traced from_ the Malabar coast _to Cobi_. +They do not exist on the south-west of Cobi and near it, where they should +in greatest force, and there is no connection, in fact, shown between +them. They do not often extend more than twenty-five miles inland, or to +the east of the Ghauts. There are no corresponding intervening monsoons +crossing India to the mountains--none over the mountains and table +lands--none under the northern lee of the mountains--nor, in short, on the +whole track, nor any S. W. winds except such as naturally belong to the +action of the curving counter-trade. + +Finally, the investigations of Commodore Wilkes on Mauna Loa, a mountain +upon Hawaii, more than 13,000 feet high, and the observations of Professor +Wise and other aeronauts are sufficient to put this whole matter of heated +lands and ascent of the atmosphere as the cause of winds, at rest. +Commodore Wilkes was encamped for about _twenty days_ on Pendulum Peak, in +December and January 1840. Although not up to the elevation of the +counter-trade in that latitude, he was above the local clouds which form +over the island during the day, where the sea breezes blow in with as +great strength as any where. Indeed, he was on the top of the "lofty +conical mountain" to which Caleb Williams alludes in the letter to +Professor Espy I have quoted, and above the spot where Professor Espy +assumed that the clouds were rising with such force as to induce the +strong sea breezes of that island. During this time there were two +snow-storms on Mauna Loa, and they had the wind from the S. W. during the +storm, as might be expected, looking at the situation of the mountain on +the western side of the island. These storms moved to the N. W., and were +observed at the other islands in that direction as rain. + +The local clouds lay over the island every day, as they do over active +volcanic islands which are very elevated, although it was the dry season. +_Nothing like an ascent of the clouds or of the currents of air from the +ocean was observed._ On the contrary, the clouds formed before the sea +breezes set in, and the latter blew from the different sides of the island +in under the clouds, and outward again, probably on the opposite side. The +whole interior of the island is elevated, and its temperature low; and +_there was no elevation of temperature on the high portions of the island +over which the clouds formed, and toward which the winds blew, which could +create an upward current_. + + "During our stay on the summit, we took much pleasure and interest in + watching the various movements of the clouds; this day in particular, + they attracted our attention; the whole island beneath us was + covered with a dense white mass, in the center of which was the cloud + of the volcano rising like an immense dome. All was motionless until + the hour arrived when the sea-breeze set in from the different sides + of the island; a motion was then seen in the clouds, at the opposite + extremities, both of which seemed apparently moving toward the same + center, in undulations, until they became quite compact, and so + contracted in space as to enable us to see a well defined horizon; at + the same time there was a wind from the mountain, at right angles, + that was affecting the mass, and drawing it asunder in the opposite + direction. The play of these masses was at times in circular orbits, + as they became influenced alternately by the different forces, until + the whole was passing to and from the center in every direction, + assuming every variety of form, shape and motion. + + "On other days clouds would approach us from the S. W. when we had a + strong N. E. trade-wind blowing, coming up with cumulus front, + reaching the height of about eight thousand feet, spreading + horizontally, and then dissipating. At times they would be seen lying + over the island in large horizontal sheets as white as the purest + snow, with a sky above of the deepest azure blue that fancy can + depict. I saw nothing in it approaching to blackness at any time." + (Exploring Expedition, vol iv. p. 155). + +Here, in the last paragraph, we have the whole truth disclosed. The N. E. +trade was blowing on Mauna Loa, 13,000 feet above the sea, and the +sea-breeze blew in on the _leeward side_, its moisture condensing over the +volcanic island, but without rising _up the mountain_, or _through the +surface-trade_, or _above 8,000 feet_. + +So, too, the celebrated aeronaut, Mr. Wise, in the course of more than a +hundred ascensions, some during high wind, and others during rain storms, +never met with an ascending current, except in a single instance, in the +body of a hail-cloud, and then there were descending currents also, the +usual intestine motion of hail-cloud with its opposite polarities. + +I copy a description of his passage through the clouds of a rain-storm, +and his floating a long period above them; and there was no ascending +current which disturbed their horizontal repose or progression. The double +layer is not uncommon--condensation taking place at the connection of the +upper and lower portions of the trades, with the surrounding atmosphere; +or in the trade, and by _induction in the surface atmosphere_ at the same +time. Such instances are frequently visible, and if his ascensions had +been undertaken at other times in stormy weather he would have seen more +of them. + + "Before I passed the limits of the borough, a parachute, containing + an animal, was dropped, which descended fast and steady, and, just as + it reached the earth, my ærial ship entered a dense black body of + clouds. Ten minutes were consumed in penetrating this dismal ocean of + rainy vapor, occasionally meeting with great chasms, ravines, and + defiles, of different shades of light and darkness. When I emerged + from this ocean of clouds, a new and wonderfully magnificent scene + greeted my eyes. A faint sunshine shed its warmth and luster over the + surface of this vast cloud sea. The balloon rose more rapidly after + it got above it. Viewing it from an elevation above the surface, I + discovered it to present the same shape of the earth beneath, + developing mountains and valleys, corresponding to those on the + earth's surface. The profile of the cloud-surface was more depressed + than that on the earth, and, in the distance of the cloud-valley a + magnificent sight presented itself. Pyramids and castles, rocks and + reefs, icebergs and ships, towers and domes--every thing belonging to + the grand and magnificent could be seen in this distant harbor; the + half-obscured sun shedding his mellow light upon it, gave it a rich + and dazzling luster. They were really "castles in the air," formed of + the clouds. Casting my eyes upward, I was astonished in beholding + another cloud-stratum, far above the lower one; it was what is + commonly termed a "mackerel sky," the sun faintly shining through it. + The balloon seemed to be stationary; the clouds above and below + appeared to be quiescent; the air castles, in the distance, stood to + their places; silence reigned supreme; it was solemnly sublime. + Solitary and alone in a mansion of the skies, my very soul swelled + with emotion; I had no companion to pour out my feelings to. Great + God, what a scene of grandeur! Such were my thoughts; a reverence for + the works of nature, an admiration indescribable. The solemn + grandeur--the very stillness that surrounded me--seemed to make a + sound of praise. + + "This was a scene such that I never beheld one before or after + exactly like it. Two perfect layers of clouds, one not a mile above + the earth; the other, about a mile higher; and, between the two, a + clear atmosphere, in the midst of which the balloon stood quietly in + space. It was, indeed, a strange sight--a meteorological fact, which + we cannot possibly see or make ourselves acquainted with, without + soaring above the surface of the earth." (History and Practice of + Aeronautics, p. 209). + +This is graphic. Perhaps in relation to the conformity of the upper +surface of the inferior layer of clouds, to the irregularities of the +earth's surface, he was misled during the enthusiasm of the moment. He is +certainly mistaken as to the possibility of observing these double layers +from the earth; I have seen them in hundreds of instances. But in relation +to the _quiescence_ of the clouds for an hour, and _the entire absence of +ascending currents_, he could not be mistaken. + +And now, in the absence of all direct proof to sustain the hypothesis, +that the heating of the land produces ascending currents, and thereby the +winds, and especially the monsoons, and in view of all the adverse +evidence, I put it to Lieutenant Maury, and every sincere searcher after +meteorological truth, whether the theory should not be abandoned. + + + + +CHAPTER VII. + + +The counter-trade of the northern hemisphere ranges at different heights +in different latitudes, in the same latitude at different seasons, and +also upon different days of the same season; and, like the line of +perpetual snow, has its greatest elevation in the tropics, descending +gradually to the surface of the ocean at the poles. At the northern limit +of the N. E. trades, it does not, ordinarily, approach the earth +sufficiently near for decided reciprocal action. Hence, at that point, +storms do not often originate; the winds are lighter and more variable, +and calms are more frequent than at any point, except at the meeting and +elevation of the trades, or in the polar regions. Doubtless this state of +things is increased by the feebler action of north polar magnetism, and +the irregular action of the longitudinal magnetic currents, evinced by the +irregular, and often, feeble action of the trades, near their extreme +limits. They are not unfrequently wholly wanting, near the northern limit, +for several days in succession, and calms and baffling winds are found in +their place--another effect of the irregular action of terrestrial +magnetism, consequent upon the ever-changing transit of central activity +from south to north, and from north to south. Upon the islands, however, +and continents, which have elevated mountain peaks and ridges, especially +if of volcanic origin and activity, which approach more nearly the path of +the counter-trade, a different state of things exists. There, showers and +gusts are frequent. Thus, upon the Sandwich Island, Kauai, the most +northern one, which is within the region of the N. E. trade during ten +months of the year, and upon its volcanic peaks and elevated table-lands, +and north-easterly from them, over the district of Waioli, rain falls in +abundance during the year, while the coastlines upon other portions of the +island can not be cultivated without irrigation. (See Wilkes' Exploring +Expedition, vol. iv. pp. 61 and 71; and American Journal of Science and +Art, for May, 1847). + +A like state of things, in degree, may be found upon the Canaries, and the +more elevated of the West India Islands. The Cape de Verdes are an +exception, and the Christian world are quite often called upon for +contributions of provisions, to save the inhabitants of these islands from +starvation. They lie at the northern limit of the equatorial belt, and for +a period of two months only (July and August), are supplied with rain. If, +from any cause, the belt does not move as far north as usual during any +season, unbroken drought and famine are sure to overtake them. The islands +contain some elevated peaks, and are of volcanic origin, but not of +present volcanic activity, and the counter-trades as they issue from the +equatorial belt at their highest elevation, are too far above them for +reciprocal, influential action. If the islands could be placed 10° further +north, we should hear no more of drought or famine from them, and their +quantity of rain and fertility would be not only more permanent, but much +increased. Superadded to this, is the fact, that at that point the belt of +rains precipitates feebly because the S. E. trade originates upon the +southern part of the continent of Africa, and the N. E. mainly, upon the +desert and the Barbary States--and both are sparingly supplied with +moisture. + +The same state of things is strikingly obvious upon continents wherever +the mountains are sufficiently elevated, even within the trade-wind +region. Thus, in South America, the Andean ranges are of great elevation, +and spurs and table-lands extend from them a considerable distance to the +eastward. There, the S. E. and N. E. trades of the Atlantic meet in very +considerable volumes, and not only is the equatorial belt much wider than +upon the Atlantic and Pacific, but the counter-trades are met upon the +elevated peaks and mountain-ranges, and showers and storms on their +eastern slopes and summits are frequent during the dry season--down even +to the extra-tropical belt. I have already said that it was probable that +the great elevation of the Andes diverted and turned south a portion of +the N. E. counter-trade which would otherwise pass over the western coast +of Peru. + +The report of Lieutenant Herndon, which has come to my notice since that +was written, states facts which strongly corroborate that opinion. It +seems that the trades and counter-trades actually _bank up_, in their +passage to the westward, against those mountains, and the true elevation +of their eastern slopes can not be barometrically ascertained. (See report +of the Exploration of the Amazon, p. 261). Lieutenant Herndon says: + + "I was surprised to find the temperature of boiling water at Egas to + be but 208° 2', the same within 2' of a degree that it was at a point + one day's journey below Tingo Maria, which village is several hundred + miles above the last rapids of the Huallaga river; at Santa Cruz, two + days above the mouth of the Huallaga, it was 211° 2'; at Nauta, three + hundred and five miles below this, it was 211° 3'; at Pebas, one + hundred and seventy miles below Nauta, 211° 1'. I was so much + surprised at these results that I had put the apparatus away, + thinking that its indications were valueless; but I was still more + surprised, upon making the experiment at Egas, to find that the + temperature of the boiling water had fallen 3° below what it was at + Santa Cruz, thus giving to Egas an altitude of fifteen hundred feet + above that village, which is situated more than a thousand miles up + stream of it. I continued my observations from Egas downward, and + found a regular increase in the temperature of the boiling water + until our arrival at Pará, where it was 211° 5'. + + "From an after-investigation, I am led to believe that the cause of + this phenomenon arises from the fact that the trade-winds are dammed + up by the Andes, and that the atmosphere in those parts is, from this + cause, compressed, and, consequently, heavier than it is further from + the mountains, though over a less elevated portion of the earth. The + discovery of this fact has led me to place little reliance in the + indications of the barometer for elevation, at the eastern foot of + the Andes. It is reasonable, however, to suppose that this cause + would no longer operate at Egas, nearly one thousand miles below the + mouth of the Huallaga." + +The report of Lieutenant Gibbon, is also exceedingly instructive. +Separating from Lieutenant Herndon at Tarma, upon the Andes, he pursued a +southern course, along the eastern slopes of the chain from 11° 30' +south, almost to 18° south, at Ohuro, making a journey of about 7° 30' of +latitude. + +A considerable portion of this journey was over eastern and less elevated +portions of the Andes; but little below, however, the line of perpetual +snow. Here, during the dry season, he met with frequent showers and fogs +from the eastward, but left them as he descended into the plains upon the +table-land. There he found the dry season more distinctly marked; but +occasional irregularities were found upon the table-lands, as every where +upon corresponding elevations. The S. E. trades, however, were there +obvious, during the dry season, notwithstanding the irregularities. The +rainy season, from December to May, he spent at Cochabamba, and at its +close he traveled north down the Madeira and its tributaries, to the +Amazon. Although scarcely consistent with my prescribed limits, I can not +forbear making a few extracts. Thus, when on the mountains, east of +Huanvelica, in the N. E. counter-trade, he says: + + "Our course is to the eastward. The snow-capped mountains are in + sight to the west. Temperature of a spring 48°; air 44°. Lightning + flashes all around us; as the wind whirls from _north-east_ to + south-west, rain and snow-flakes become hail, half the size of peas. + Thunder roars and echoes through the mountains; the mules hang their + heads, and travel slowly; the thinly-clad aboriginal walks shivering + as he drives the train ahead; the dark cumulus cloud seems to wrap + itself around us." + +Again, at the Bombam Post-house, in the focus of change from cirrus to +cumulus, and stratus, and storm: + + "The winds are very gentle, and curl the cirrus or hairy clouds in + most graceful shapes about the hoary-headed Andes, in rich and + delicate clusters; when the peak is concealed, all but the blue tinge + below the snow, we see a natural bridal vail. An _easterly wind_ + lifts and turns them to dark, cumulus clouds, settled on the frosty + crown, like an old man's winter cap; the physiognomical expression is + that of anger. The change is accompanied by thunder, and seems to + command all around to clothe themselves for storms. The cold rain + comes down in _fine drops_ upon us; the day grows darker, and the + _clouds press close upon the earth_." + +During an excursion east of Cuzco-- + + "Turning from the river, we ascend a steep ridge of mountains--the + eastern range at last. A heavy mist _wafts upward as the winds drive + it against the side of the Andes_, so that our view is shortened to a + few hundred yards. We hope the curtain will rise that we may view the + productions of the tropical valley below; but the mist thickens, and + the day gets dark with heavy, heaped-up black clouds; a rain-storm + follows. The grasses are thrifty, and the top of the ridge covered + with a thick sod. By barometer, we stand eleven thousand one hundred + feet above the level of the sea." + +In May following, having spent the rainy season in Cochabamba, he travels +north-- + + "Our route from Tarma to Oruro was south. We traveled ahead of the + sun. In December, when we arrived in Cochabamba, the sun had just + passed us. As soon as he did so, the rains descended heavily on this + side of the ridge; it was impossible to proceed. The roads were + flooded, the ravines impassable, and the arrieros put off their + journey until the dry season had commenced. After the sun passed the + zenith of Cochabamba, and had fairly moved the rain belt after him + toward the north, then we came out from under shelter, and are now + walking behind the rain belt in dry weather, while the inhabitants + are actively employed in tending their crops." + +So on the north of the equatorial belt, along the whole line of the Andes, +up to the northern boundary of the desert valley of the Gila, rain falls +on the high mountain-ranges, owing to the contiguity of the counter-trade +and the diversion of showers to the north, along their eastern sides. + +During the survey of the boundary line between Mexico and California, +etc., by the commission under Mr. Bartlett, it became necessary to find +some spot where water and grass were abundant, for the head quarters of +the commission. This was found, and _could only be found_, upon the +Mimbres Mountains, at an old abandoned Spanish copper mine, 7,000 or 8,000 +feet above the level of the sea, surrounded with peaks of still greater +height. These elevated ranges were within influential distance of the +counter-trade, and here snow fell in the winter, from the extra-tropical +belt, and rain, in showers, in summer, at the period of the most northerly +extension of the tropical belt; when fifteen miles off, in the valley, it +was unbroken drought. Mr. Bartlett thus describes it in his Personal +Narrative: + + "We reached this district on the 2d of May. Vegetation was then + forward, though there had been no rain. But it must be remembered + that during the winter there is snow, and hence a good deal of + moisture in the earth when the spring opens. The months of May and + June were moderately warm. On the third of July the first rain fell. + It then came in torrents, accompanied by hail, and lasted three or + four hours. Many of our adobe houses were deluged with water, and the + mountain-sides exhibited cataracts in every direction. The Arroyo, + which passes through the village, and which furnishes barely water + enough for our party and the animals, became so much swollen as to + render it difficult to cross; and, by the time it had received the + numerous mountain torrents, which fall into it within a mile from our + camp, it became impassable for wagons, or even mules. The dry gullies + became rapid streams, five or six feet deep, and sometimes fifty feet + or more across. On this day, a party, in coming to the copper mines, + from the plain below, _where there had been no rain_, found + themselves suddenly in a region overflowing with water, so that + their progress was arrested, and they were obliged to wait until the + flood had subsided. After this we had occasional showers, during the + months of July and August." + +The location of this mountain station is near the thirty-third degree of +north latitude, while the northern limit of the equatorial belt, nowhere, +except upon the mountain ranges and table-lands of Mexico, extends above +25°. + +There, for the reason we have been considering, it does extend further +north during July and August, in occasional showers, and in the vicinity +of Mount Picacho, Mr. Bartlett met one of its mountain thunder-storms on +the 13th of July, on his return south through Mexico, in latitude 32°, in +the following year. (Personal Narrative, vol. ii. p. 285). These showers +originated in strata of counter-trade, which had followed up along the +eastern side of the mountains and not from strata which had crossed them +and curved to the eastward, as is shown by the course of progression of +the showers. + +Let us look, in this connection, at a fact or two of great interest, +though not directly connected with the point in hand. The southern limit +of the extra-tropical belt in winter, on the Pacific coast of North +America, is in the vicinity of San Diego, at about 32°. In summer, that +limit is carried up above Astoria, which is in latitude 46° 11'--about +14°--yet New Mexico receives little if any rain in winter in the vicinity +of Albuquerque, but does receive a limited supply of about seven inches in +summer and autumn, five and a half inches of which falls in June, July, +and August. Albuquerque is in latitude 35° 13', below the southern summer +limit of the extra-tropical belt, and north of the northern limit of the +equatorial belt. This anomaly is explained by the extension west over +northern New Mexico, of the extreme western edge of our concentrated +counter-trade, by reason of its issuing further west from the equatorial +belt in its northern extension in the summer months. This western edge, in +curving to the east, north-east of New Mexico, covers the north-western +States, Iowa, Minnesota, Wisconsin, etc., and furnishes them that great +excess of summer precipitation which is a peculiarity of their climate; +and its absence further east in winter, and the very great elevation of +the Rocky Mountains and other ranges over which their ordinary +counter-trade of that season curves, account for the absence of much +precipitation and snow there, or over the valley of the Rio Grande in New +Mexico, in winter. + +We may now see, too, why the western coast and the Pacific region of the +continent, below 45°, are so deficient in moisture. The S. E. trades, +which arise from the western portion of the south Atlantic and the +continent of South America, which, if it were not for the Andes chain, in +their natural course, after passing the equatorial belt, would continue on +to the north-west until they passed the limits of the N. E. trades, and +curve in upon the western portion of our continent below 45°, and supply +it bountifully with rain, are, in part, perhaps, diverted along the +eastern side of those mountains to swell the volume of our counter-trade, +and in part pass them, almost exhausted of their supply of moisture by +their contiguous reciprocal action. Hence, too, the deficiency of +precipitation at the base of the Andes, on the western side, and the +peculiar and irregular character of the winds under the western lee of the +Andean range. Baffling airs and bands of calms prevail on this portion of +the Pacific, except where the mountains fall off, and then there is a +westerly or south-westerly monsoon under the equatorial belt. Says +Lieutenant Maury in his Charts, sixth edition, p. 731: + + "The passage, under canvass, from Panama to California, as at present + made, is the most tedious, uncertain, and vexatious that is known to + navigators. + + "My investigations have been carried far enough to show that at + certain seasons of the year a vessel bound from Panama to California, + must cross at least three, at some seasons four, such meetings of + winds or bands of calms, before she can enter the region of the N. E. + trades. Hence the tedious passage." + +Such will ever be the state of things on this continent and upon the +eastern Pacific, so long as the S. E. counter-trades are compelled to pass +over the mountain chain of South and Central America. + +Again, if we examine carefully the belt or zone of extra-tropical rains, +we shall find that the focus of greatest precipitation is considerably +north of its southern limit, and that, other things being equal, this +focus travels north in summer, and gives to higher latitudes their needed +summer rains. This is very apparent upon the north-western portion of our +continent, as the following table will show: + + +----------------------------------------------------------- + | | Lat. |Jan.|Feb.|Mar.|Apr.|May.|June.| + | |-------|----|----|----|----|----|-----| + |San Diego, Cal. |32° 41'| 0.3| 1.7| 1.1| 0.9| 0.5| 0.0 | + |San Francisco. |37° 48'| 1.7| 0.5| 4.4| 2.1| 0.4| 0.0 | + |Cant., Far W., Cal.|39° 02'| 3.3| 0.6| 6.4| 2.2| 0.9| 0.0 | + |Astoria, Oregon. |46° 11'|27.0|10.9| 6.1| 4.4| 5.9| 2.6 | + |Puget's S'd, Ore. |47° 07'|11.8| 3.9| 4.7| 4.1| 0.8| 0.6 | + |Sitka, Russ. Am. |57° 3'| 2.5| 9.6| 3.5| 3.3| 1.9| 5.9 | + +----------------------------------------------------------- + + ---------------------------------------+ + |July.|Aug.|Sept.|Oct.| Nov.|Dec.|Year.| + |-----|----|-----|----|-----|----|-----| + | 0.0 | 0.2| 0.0 | 0.1| 1.5 | 3.4| 9.6| + | 0.0 | 0.0| 0.4 | 0.6| 3.0 | 5.5| 18.8| + | 0.0 | 0.0| 0.3 | 0.1| 3.5 | 4.6| 21.9| + | 0.0 | 2.3| 1.9 | 6.7|13.2 | 6.2| 87.2| + | 0.5 | 1.3| 1.6 | 3.6| 5.9 | 6.1| 44.8| + | 3.7 |10.1|14.8 |12.7| 7.4 | 4.2| 79.5| + ---------------------------------------+ + + The figures are for inches and tenths of an inch of rain. + +Thus, it will be seen that in January, when the southern line is at San +Diego, at the south line of California, the focus of precipitation is over +Oregon; and that in August and September when the southern line is carried +up and over Oregon, the focus has traveled north to Sitka, and that it is +always at least 10° north of the southern line of the belt upon that +coast. The increased quantities of rain which fall at the focus of +precipitation there, from Oregon up, are doubtless much enhanced by the +equatorial oceanic current which flows over opposite that part of the +continent. A like effect, precisely, is produced in Europe. The quantity +of rain which falls at Bergen, in Norway, being 87-61/100 inches per year, +more than three times the average for that continent. + +The difference shown in the foregoing table, between Astoria and Puget's +Sound, is owing to the fact that the latter lies in the interior and +within the coast range of mountains, while Astoria is situated at the +mouth of the Columbia River, with an open view of the ocean. + +A like comparative increase of precipitation in northern latitudes, in +summer, is found every where varying according to the local influences +which operate in the particular case. Thus, + + ------------------------------------------------------------------------ + There falls in |Winter.|Spring.|Summer.|Aut'mn.| Year. + ---------------------------------|-------|-------|-------|-------|------ + Burlington, Vt., lat. 44° 20' | 5.7 | 7.3 | 11.4 | 9.8 | 33.9 + Albany, N. Y., lat. 42° 39' | 8.3 | 9.8 | 12.3 | 10.3 | 40.7 + Minnesota, Iowa, lat. 41° 28' | 7.3 | 12.3 | 17.4 | 11.7 | 48.8 + St. Peters'g, Russ., lat. 59° 56'| 3.89 | 3.20 | 5.70 | 4.71 | 17.51 + Pekin, China, lat. 40° | .54 | 3.35 | 18.80 | 2.29 | 25.68 + ------------------------------------------------------------------------ + +Pekin lies in the northern part of China, and would have a much larger +fall of rain from a concentrated counter-trade, but for the numerous +mountain-ranges which intersect its path in winter, but over which it +passes at a greater elevation during the summer--a peculiarity from which +the eastern section of this country is most remarkably and happily free. + +Thus, it is obvious that the focus of precipitation in the zone of extra +tropical rains, is some 8° to 12° north of its southern line, and travels +with the whole machinery in its annual transit north and south. + +It is a question of some difficulty, perhaps, whether this focus is +increased by the increase of magnetic action at this point, for both the +line of descent of the counter-trade, and the focus of magnetic action, +are carried up in a like manner, and for a like cause, and, in all +probability, both concur in the result. + +There is exceeding wisdom in this provision for the gradual subsidence of +the counter-trade, and gradual increase of magnetic intensity, and +consequent gradual precipitation. On the European continent, and over +western Asia, there are 50° of latitude to be supplied with moisture by +this polar belt of rains. If the focus of precipitation was at its +southern border, the counter-trade would be deprived of its moisture at +that point, and little would reach the more northern portions of the globe +which are to be supplied by it. But the movement of the whole machinery +carries up the southern line from the south boundaries of the Barbary +States on to the Mediterranean and portions of southern Europe, and the +focus of precipitation and of near approach of the counter-trade to the +earth, being situated far north of the southern line, is carried up +correspondingly, while the combination of the moisture with the atmosphere +by south polar magnetism and electricity, and the gradual descent of the +counter-trade, enable it to resist, to some extent, the influence of north +polar magnetism and cold, and thus retain portions of its moisture for +distribution in the polar regions. + +_The elevation of the counter-trade above the earth varies in the same +latitude with the variations in the phenomena of the weather._ An +attentive observation of the clouds of our climate will soon satisfy any +one of this, after he has become familiar with them, so as to distinguish +with certainty the clouds of the trade. Its range, in this country, is +from 3,000 feet, or less, to 12,000 feet above the earth, and its depth +with us probably, from 6,000 to 8,000 feet. Gay-Lussac, in his scientific +experimental balloon ascension, the first of _that character_ ever made, +except an imperfect one just previous, by himself and Biot, found it at +about 12,000 feet over Paris, and about 4,000 feet in depth. It is +detected by the thermometer when much elevated. + +The atmosphere grows cool as it is ascended on mountains, or by balloons. +The rate of cooling is ordinarily about 1° of Fahrenheit for every 300 +feet. If it were not for the equatorial current, this progressive decrease +of temperature would doubtless be perfectly uniform. Of Gay-Lussac's +ascension, on this point it was said: + + "At forty minutes after 9 o'clock, on the morning of the 15th + September, 1804, the scientific voyager ascended, as before, from the + garden of the repository of models. The barometer then stood at 30.66 + English inches, the thermometer at 82° Fahrenheit, and the hygrometer + at 57-1/2°. The sky was unclouded, but misty. + + "During the whole of this gradual ascent, he noticed, at short + intervals, the state of the barometer, the thermometer, and the + hygrometer. Of these observations, amounting in all to twenty-one, he + has given a tabular view. We regret, however, that he has neglected + to mark the times at which they were made, since the results appear + to have been very materially modified by the progress of the day. It + would likewise have been desirable to have compared them with a + register, noted every half hour, at the Observatory. From the surface + of the earth to the height of 12,125 feet, the temperature of the + atmosphere decreased regularly, from 82° to 47° 3' by Fahrenheit's + scale; _but afterward it increased again, and reached to 53° 6' at + the altitude of 14,000 feet_; evidently owing to the influence of the + warm currents of air which, as the day advanced, rose continually + from the heated ground. From that point the temperature diminished, + with only slight deviations from a perfect regularity. At the height + of 18,636 feet the thermometer subsided to 32° 9', on the verge of + congelation; but it sunk to 14° 9' at the enormous altitude of 22,912 + feet above Paris, or 23,040 feet above the level of the sea, the + utmost limit of the balloon's ascent." + +The high range of the barometer indicated a very considerable elevation +of the trade at the time Gay-Lussac made his ascension. I am not aware +that it has since been found at so great an elevation, in so high a +latitude, though it is undoubtedly elevated by the interposition of a +large volume of N. W. air, upon some occasions, to nearly the same +altitude with us. + +In the extract in relation to the ascension of Gay-Lussac, we have another +of the thousand hastily-adopted and absurd hypotheses connected with the +caloric theory. It is obviously and utterly _impossible_ that in addition +to the ordinary accumulation of heat at the surface of the earth "_as the +day advanced_"--that is, _during the forenoon_, warm currents should +ascend, unobserved by Gay-Lussac during an ascent of 12,000 feet--not +_affecting in the least_ so large an intervening body of the atmosphere or +his thermometer, and in such immense volumes as to increase the warmth of +a stratum of 4,000 feet in depth, an average of 3° of Fahrenheit, and to +the extent of 6° at the center. + +Very few balloon ascensions have been made with a view to scientific and +accurate observation. But other aeronauts have met the counter-trade at +different altitudes, and in both clear and stormy weather. + +Recently, in 1852, four ascensions were made in England, under the +direction of the Kew Observatory Committee, of the British Association. I +copy from the August number of the "London, Edinburg, and Dublin +Magazine," for 1853, the following condensed amount of the result: + + "The ascents took place on August 17th, August 26th, October 21st, + and November 10th, 1852, from the Vauxhall Gardens, with Mr. C. + Green's large balloon. + + "The principal results of the observations may be briefly stated as + follows: + + "Each of the four series of observations shows that the progress of + the temperature is not regular at all heights, but that at a certain + height (_varying on different days_) the regular diminution becomes + arrested, and for the space of about 2,000 feet the temperature + remains constant, or even increases by a small amount. It afterward + resumes its downward course, continuing, for the most part, to + diminish regularly throughout the remainder of the height observed. + There is thus, in the curves representing the progression of + temperature with height, an appearance of _dislocation_, always in + the same direction, but varying in amount from 7° to 12°. + + "In the first two series, viz.: August 17th and 26th, this peculiar + interruption of the progress of temperature is strikingly coincident + with a _large_ and _rapid fall_ in the temperature of the + _dew-point_. The same is exhibited in a less marked manner on + November 10th. On October 21st a dense cloud existed at a height of + about 3,000 feet; the temperature decreased uniformly from the earth + up to the _lower_ surface of the cloud. When a slight rise commenced, + the rise continuing through the cloud, and to about 600 feet above + its upper surface, when the regular descending progression was + resumed. At a short distance above the cloud, the dew-point fell + considerably, but the rate of diminution of temperature does not + appear to have been affected in this instance in the same manner as + in the other series; the phenomenon so strikingly shown in the other + three cases being perhaps modified by the existence of moisture in a + _condensed_ or vesicular form. + + "It would appear, on the whole, that about the principal plane of + condensation heat is developed in the atmosphere, which has the + effect of raising the temperature of the higher air above what it + would have been had the rate of decrease continued uniformly from the + earth upward." + +These gentlemen do not adopt the absurd explanation of the French +philosophers; they account for the phenomenon by supposing heat to be +_developed_ at that particular part of the atmosphere; but they are +equally wide of the mark. They found the excess of heat there to the +extent of 7° to 12°, and on days when there was no condensation, or other +assignable cause for its _development_. + +The temperature of the counter-trade partakes, doubtless, of the +temperature of the adjoining strata at its upper and lower portion, and +has never been found much, if any, higher than 60° at the center. Nor +could it be expected. The trade, in its upward curving course, within the +tropics, attains a considerable altitude where the atmosphere is +comparatively cold, and necessarily loses a portion of its heat there, and +during its northern flow. Probably its central summer range, in the +latitude of Paris, is not far from 55°, and with us 60°. + +The contrast between the trade and the surrounding atmosphere, in winter, +is much more striking, and this has been observed particularly upon the +Brocken of the Alps, and in the polar regions. + +"In all seasons the temperature is higher on the Brocken, on a serene, +than on a cloudy day, and, in the month of January, _the serene days were +warmer than at Berlin_." (Kämtz's Meteorology, by Walker, p. 217.--Note.) + +As the portion of the counter-trade, which does not become depolarized--in +diminished volume--progresses toward the polar regions, it settles nearer +the earth, and within the Arctic circle is found but little way above it. +Thus, in December, 1821, Parry, at Winter Island, in latitude 66° 11', +flew a kite, with a thermometer attached, to the height of 379 feet, and +found that the temperature, instead of falling 1-1/4°, the usual ratio of +decrease, rose 3/4 of a degree. + +The same thing was observed at Spitzbergen, in latitude 77° 30' north, and +at Bosekop, latitude 69° 58', by a scientific commission, and by means of +kites, confined balloons, and the ascent of elevations. + + "In winter the temperature goes on increasing with the height, up to + a certain limit, which is variable, according to the different + atmospheric circumstances, the influence of which is not yet very + exactly known. The hour of the day appears to be indifferent, since + there exists no thermometric diurnal variation in the strata of the + surface. The mean of thirty-six experiments, made with kites, or with + captive balloons, at Bosekop, latitude 69° 58' north, has given a + mean rate of increase of 1° 6' for the first hundred meters.[6] + Beyond this limit, and even beyond the first 60 or 80 meters, the + temperature again becomes decreasing, at first very slowly, but + afterward the decrease is accelerated. The observations that have + been made on the flanks, or on the summits, of mountains, during the + same expeditions, entirely confirm these results. The cooling + influence of a soil, that radiates its own heat for several weeks, + without receiving any thing on the part of the sun, in compensation + of its losses, the influence of _counter-currents from above_, coming + from the west and the south-west, with a high temperature, account + for this anomaly, which, in winter, represents the normal state of + the most northern parts of the European continent." (Walker's Kämtz, + p. 515.--Note.) + +Mr. Walker is the only author, so far as I know, who has suspected the +true cause of the phenomenon, viz.: "currents from above coming from the +west and south-west, with a high temperature;" but the caloric theory +"sticks like a burr," and he adheres also to the idea that a snow-clad +surface, in the absence of the sun, can aid, by radiation, in warming the +atmosphere for a distance of several hundred yards above it, increasing +the warmth as the distance from the earth increases! + +This contrast between the counter-trade and the adjacent atmosphere, in +winter, in latitudes as low as that of the Brocken, is probably heightened +by the increased warmth of the former, at that season. The S. E. trades +then form under a vertical sun, and the difference of temperature can not +be less than from 6° to 8°. Not unfrequently in winter and spring the rain +will fall with a temperature of 50° to 55°, when the atmosphere near the +earth is 10° or 20° or more, below those points; and it is frozen to every +object upon which it falls. The trade stratum, from which it descends, is +not warmed by "radiation" or by ascending currents from a snow-clad +surface, and during a cloudy day; nor by a "development of heat" at that +particular altitude, but it has brought its heat from the South Atlantic, +and imparts it to the rain which forms within it. There is every reason to +believe that the counter-trade flows north in a regular descending plane, +not materially differing from that of the line of perpetual snow. The +descent of the latter is well ascertained to be from about 16,000 feet at +the equator, to _the surface_ at the poles. The plane of the counter-trade +is probably much the same, varying over different localities, from the +varied action between it and the earth which we are considering; and +probably both correspond with the increase of magnetic intensity. + +Lieutenant Maury, in an able and original article upon the circulation of +the atmosphere, conceives the bands of comparative calms at the northern +limits of the trades, which he appropriately terms the "_Calms of +Cancer_," to be nodes in the circulation of the atmosphere, and that the +upper or counter-trade here decends and becomes a surface wind from the S. +W., as the N. E. trade is a surface wind; and that an upper current from +the poles approaches and descends at the same node, to make the N. E. +trade. But it is evident he adopted that conclusion too hastily, as he +obviously did the conclusion that the calms of the horse latitudes were a +type of all. We have seen that the latter are increased by a diversion of +the counter-trade, and that they are avoided by making easting. So it may +be observed that our upper current is a S. W. current, and no northerly +upper current is visible, or exists over the country, however it may be in +western Europe and the North Pacific, on the west of the magnetic poles, +where cold, dry northerly and north-easterly winds are found. The origin +and progress of storms withal demonstrates that no such node can exist. + +Two points have been made in relation to the course of the counter-trade +in the tropics, and are relied upon to show its progress there to the N. +E., which deserve consideration. + +In the first place, it is well known that "rain dust" falls in +considerable quantities on the western coast of Africa, particularly about +the Cape de Verde Islands, and also upon the Mediterranean and +south-western Europe, where it is termed "sirocco dust." + + "This dust," says Lieutenant Maury, "when subjected to microscopic + examination, is found to consist of infusoria and organisms, whose + _habitat_ (place of abode) is not Africa, but South America, and in + the S. E. trade-wind region of South America. Professor Ehrenberg has + examined specimens of sea dust, from the Cape de Verdes and the + regions thereabout, from Malta, Genoa, Lyons, and the Tyrol, and he + has found such a similarity among them as would not have been more + striking had these specimens been all taken from the same pile. + + "South American forms he recognizes in all of them; indeed, they are + the prevailing form in every specimen he has examined. + + "It may, I think, be now regarded as an established fact, that there + is a perpetual upper current of air from South America to north + Africa, and that the volume of air in these upper currents, which + flows to the northward, is nearly equal to the volume which flows to + the southward with the N. E. trade-winds, there can be no doubt," + etc. + +Now, it is doubtless true that this dust is transported in a +counter-trade, and that such dust is found in South America, and is taken +up there by sand-spouts, like those of the ocean in form and action. Both +Humboldt and Gibbon have graphically described them. Yet I do not think +the point well taken. South-eastward of the Cape de Verdes, where the +surface-trades--which, becoming counter-trades, pass over these islands, +and, recurving, pass over the Mediterranean and south-western +Europe--should originate, there is a vast extent of unexplored continent +in the same latitude as the portion of South America where the dust is +found; and the same dry seasons, and the same spouts, in all probability, +exist in both. Until it be shown that such forms have no "_habitat_" in +central and southern and unexplored Africa, upon the same latitudes as in +South America, it may fairly be presumed that the dust is taken up there. +Indeed, the _curve_ upon which this dust is found to fall, in the greatest +quantities, is very remarkable, and corresponds remarkably with the _law +of curvature_ of the counter-trade we have considered, and with the +progress of a storm upon that coast, and over the Mediterranean, +investigated by Colonel Reid. (See Reid, on Storms and Variable Winds, p. +276.) This _curve clearly indicates the origin of the dust in South +Africa_. + +The second point is, that ashes from the volcanos of Mexico and Central +America have fallen to the north-east of the place where they were +ejected. Mr. Redfield has grouped these instances of volcanic eruption +usually cited, and I copy from him: + + "We learn from Humboldt, that in the great eruption of Jorullo, a + volcano of southern Mexico, which is 2,100 feet above the sea, in + latitude 18° 45', longitude 161° 30', the roofs of the houses in + Queretaro, more than 150 miles north, 37° east from the volcano, were + covered with the volcanic dust. In January, 1845, an eruption took + place in the volcano of Cosiguina, on the Pacific coast of Central + America, in latitude 13° north, and having an elevation of 3,800 + feet, the ashes from which fell on the island of Jamaica, distant 730 + miles north, 60° east from the volcano. The elevated currents by + which volcanic ashes are thus transported are seldom or never of a + transient or fortuitous character; and these results, therefore, + afford us one of the best indications of their general course. Thus, + the progress of the higher portion of the trade-wind was marked by + the eruption of Tuxtla, latitude 18° 30', longitude 95°, which + covered the houses in Vera Cruz with ashes, at the distance of 80 + miles north, 55° west, and also at Peroté, 160 miles north, 60° west. + The ashes from the volcano, at St. Vincent, which fell at Barbadoes, + and east of that island, in 1812, mark the course of a current from + the westward, which appears there at times, in the region of clouds, + and may, perhaps, be connected with the permanent winds on the + Pacific coast of Mexico." + +As to one of the instances cited in the foregoing paragraph, that of +Tuxtla, it may be laid out of the case--the direction conforming +substantially to the assumed course of the counter-trade at that point. +St. Vincent lies W. N. W., or nearly so, of Barbadoes, and a N. W. or +westerly surface-wind, prior to, and during storms, is common in the West +Indies as the N. E. is here--both alike, blowing in opposition to the +progressive course of the storm. There is nothing strange or peculiar, +therefore, respecting that instance, or the existence of variable and +especially S. W. currents, between the trades, with occasional partial +condensation. + +The falling of the ashes from Cosiguina, upon Jamaica, has long and often +been cited, as proof that in the West Indies the prevailing upper currents +run from the S. W. But it has been ascertained that, _during the same +eruption, ashes fell 700 miles to the westward, on the deck of the +Conway_, a vessel then upon the Pacific Ocean. That case, therefore, does +not prove the absence of the S. E. counter-trade at the time, but only the +presence of another, and a different current above or below it--and it may +have been either, and transient. + +So of the Jorullo instance. Investigation would probably have shown that +ashes fell to the N. W., and that they were carried N. E. by a transient +S. W. wind produced by the existence of a storm to the eastward, or one of +those states of partial condensation of the counter-trade which often +produce currents at greater distances without a storm. Not one of these +cases disproves the existence of a S. E. counter-trade, and the invariable +N. W. progression of the storms of those latitudes demonstrates it. + +Occasional anomalous currents, depending upon storm action at considerable +distance, are found in our atmosphere, and doubtless are there also. Thus, +although the N. W. wind is almost invariably a surface wind, I have, in a +few instances, seen a N. W. set at a considerable elevation, converging +toward a peculiarly stormy state of atmosphere far south of us, about the +period of the spring equinox. And so in one or two instances I think I +have seen light cirro-stratus clouds _above_ the counter-trade, when it +ran very low, setting from the N. E., although the usual and almost +invariable location of the N. E. wind is below the counter-trade and the +stratus clouds of the storm. Aeronauts, too, have found these secondary +currents beneath a serene and cloudless sky. Indeed, the S. E. +counter-trade doubtless often induces a thin secondary current of S. W. +wind between itself and the surface-trade, in the same manner that similar +currents are induced with us, and every where. + +A question arises here of considerable interest, which, I confess, I can +not answer to my own satisfaction. It is, whether there be, or not, _an +eastern progression of the body of the atmosphere above the machinery of +distribution_. I have thought there was, and that in set fair weather I +had seen a peculiar kind of cirro-cumulus cloud, in patches, the small +cumuli very distinct and rounded, moving due east, which indicated such a +current. But I am not satisfied, from my own observation, that it is so, +nor is it easy to determine the question. The moisture of evaporation +rarely, if ever, ascends to any considerable elevation, and the upper +strata must be very dry. Hence, condensation, if it takes place, is thin, +and perhaps often undiscernable. Investigations upon mountains prove +little, for the winds of the inferior strata rush up their sides and over +them. It is an open question, and future observation may solve it. The +prevailing opinion seems to be that there is. If the theory of Oersted, in +relation to the circular currents of a magnet, be true, there should be +such a progression produced by opposite secondary currents, unless, +indeed, it be also true that those currents are inoperative at so great a +distance, or their influence barely suffices to retain the attenuated +atmosphere in its place. Perhaps the investigations of Ampère conflict +with it. But it is worth while, I think, for philosophers to inquire +whether the transverse position of the needle upon the wire is not the +effect of the central _longitudinal_ currents, conforming to the circular +currents of the wire, and whether it is not owing to the production of the +same currents in a globe by the circular currents of Ampère, that the +globe is magnetized, and the needles made to dip. + + + + +CHAPTER VIII. + + +It is exceedingly desirable, in a practical point of view, to understand +the precise character of the reciprocal action which takes place between +the earth and the counter-trade, and produces the varied phenomena which +mark our climate. We have seen that the same laws, other things being +equal, operate every where, and that analogies may be sought in the +character of those phenomena elsewhere, under the same, or different, +modifying circumstances. Looking, therefore, at the magneto-electric +movable machinery as a whole, and its influence upon the atmospheric +circulation and conditions, we find many facts which point to a primary +action in the counter-trade, and others that point as significantly to a +primary local-inducing-action in the earth. Let us briefly review those to +which we have alluded, and advert to some others, and see what solution of +the question they will justify: + +The belt of inter-tropical rains appears to be, in width, and amount of +precipitation, and annual travel north and south, proportionate to the +volume of trades which blow into it, the quantity of moisture they +contain, and the elevation of the surface over which they meet. + +South America is the most thoroughly-watered country within the tropics, +except, perhaps, portions of Hindoostan, Burmah, Siam, etc., on +south-eastern Asia. The contrast between both, and Africa, as far as +explored, and as shown by its rivers, is most obvious. The Amazon, alone, +delivers more water to the ocean than all the rivers of Africa. + +Of the width of the belt of rains over Africa, in the interior, we know +little. Its northern extension is less, by from 7° to 10°, than the same +belt over South America, the West Indies, and Mexico. Probably its +southern is also. Upon South America, the southern edge is carried down to +Cochabamba, in latitude 18°, and probably to 25°, to the northern edge of +the coast-desert of Peru, while it is rarely, if ever, found over the +Atlantic below 7°, a difference of 12° to 20°. Over South America, too, +the quantity of water which falls is also vastly in excess of that which +falls upon the Atlantic. The main cause of these differences is obvious. +The N. E. counter-trades which blow over Africa, originate on a surface +which is rainless, as eastern Sahara, Egypt, Arabia, etc., or subject to a +dry season by the northern ascent of the southern line of the +extra-tropical belt, as the Barbary States, Syria, Persia, etc., and their +supply of moisture is necessarily scanty. On the south, the S. E. trades +originate, in part, upon the eastern portion of southern Africa, and, in +part, upon the Indian Ocean, and from the latter source, and a portion of +the Mediterranean, doubtless most of the water which falls upon Central +Africa, is derived. + +The N. E. and S. E. trades which blow into the inter-tropical belt upon +the eastern portion of the Atlantic, originate upon similar surfaces, and +with like effect. Thus, the S. E. trades, in summer, are from the Southern +portion of Africa, and the N. E., in part, from the Mediterranean; and, in +winter, the N. E. from the deserts, Senegambia, Nigritia, etc., and the S. +E., owing to the narrowing of the African continent, mainly from the South +Atlantic and Indian Oceans. Going west, the belt widens, and its range +increases until the Andes are reached; but under their lee, on the western +side, a totally different state of things is found, and the belt of the +coast becomes broken and irregular, as we have seen in the citation from +Maury. + +The width, extension, and excessive precipitation of the belt, over South +America, follow the same law. The South Atlantic widens out by the +trending of the coast to the S. W., and furnishes a large area for the +unobstructed formation and evaporative action of the S. E. trades. So the +trending of the coast to the N. W., from 5° south to the northward, opens +a large area for a like formation and action of the N. E. trades. No +correspondingly favorable circumstances exist any where, except, perhaps, +around Hindoostan, and there the fall of rain is very excessive in some +places, as on the Kassaya hills, to the extent of 400 inches per annum. In +addition to this, the magnetic line of no variation, and of greater +intensity, which runs from our magnetic pole, obliquely, S. S. E., to its +opposite and corresponding pole in the southern hemisphere, enters the +Atlantic on the coast of North Carolina, and traverses it, and the eastern +portion of South America, through the whole trade-wind region. The +table-lands, and slopes, and high mountain peaks, meet the trades +successively, as they go west, and the latter wrench from them, to an +unusual extent, their moisture; depressing the line of perpetual snow, by +an increase of quantity on the eastern sides, several thousand feet, as it +is for a like cause depressed on the southern side of the Himmalayas. On +the eastern slopes and tops of the Andes, as we have seen, and owing to +their elevation, falls the moisture which, according to the working of the +machinery, and the law of curvature, should bless the coast line of Peru +and northern Chili, the eastern Pacific, northern Mexico, California, +Utah, and New Mexico; and, while the Andes stand, the curse of comparative +aridity must rest upon them all. + +Southern Chili, and western Patagonia are supplied by the N. E. trades, +which originate in the West Indies, the Gulf of Mexico, and the Caribbean +Sea, and the Pacific, off Central America, in the neighborhood of the Bay +of Panama. But there, again, the same effect of elevation is seen. The +mountain slopes of southern Chili and Patagonia are abundantly supplied, +and their mountain ranges are drenched with rain, while eastern Patagonia +and southern Buenos Ayres, under their lee, are comparatively dry. So the +S. E. trades, which originate off the western coast of South America, +curve in upon, and aided by the oceanic currents, supply, abundantly, the +N. W. coast of this continent, north of California; and there, too, the +coast, and its elevated ranges, receive, as we have seen, a very large +proportionate supply of their moisture. Substantially, the same state of +things, as far as circumstances permit, is reproduced upon Malaysia, +Hindoostan, etc., and the interposition of arid New Holland upon the +evaporating trade-surface may be distinctly traced upon south-western +Asia. Deserts abound there; the Caspian Sea receives the drainage of a +very large surface, without an outlet; their southern line of +extra-tropical rains is carried up very far in summer, and their dry +season is intensely hot. (See an article in the American Journal of +Science, for July, 1846, by Azariah Smith.) + +Another fact in this connection is worthy of a moment's consideration. The +magnetic equator, as sought by the dipping needle, is not coincident with +the geographical one. Humboldt found it, on the Andes, at 7° 1' south, and +it has been found still lower in the Atlantic. Over Africa it rises above +the geographical equator, and descends again on the Indian Ocean. About +midway the Pacific, it becomes coincident with the equator of the earth +again. (See diagram, on page 83.) Perhaps it is not known, with certainty, +why this is so. The south pole may be situated nearer the geographical +pole than the north one--but this is not believed to be so, nor could it +make the difference. The greatest southern depression of the magnetic +equator is found where the lines of greatest intensity, and of no +variation, are found; and at the more intense of these lines exists the +greatest depression. From this, I think, it may be inferred that the +needle is affected by the greater magnetic intensity of the northern +hemisphere, to which it may yet appear the obliquity of the earth's axis +is owing. However this may be, or whatever the cause, no marked effect is +produced upon the trades. The S. E. trades, by reason of the greater +extent of ocean-surface on which they originate, are every where the most +extensive, regular, and forcible. The south polar waters, from which they +rise, are every where trenching upon, and overriding, the north polar +ones; and thus, by a most beneficent provision, the greater portion of the +habitable surface is placed in the northern hemisphere, and the principal +portion of the southern is left open to an extensive, active evaporative +action, which supplies the northern habitable surface with a large excess +of the needed moisture. + +The condensation, and consequent precipitation, which takes place at the +passing of the trades, as we have already said, over the ocean and +lowlands, takes place mainly in the day-time. Upon the table-lands and +mountain-ranges, it often continues during the evening and night. The +morning, and early part of the day, however, in tropical countries, are +generally fair at all elevations. + +Storms also originate in the equatorial belt, and issuing forth in great +volume and with great intensity of action, find their way up even within +the Arctic circle. Those which pass over this continent, or the northern +Atlantic, generally originate in the West Indies, some of them over the +Caribbean Sea, some over the islands, and some over the open ocean to the +east of them; and, nearly all the most violent, during the months of +August, September, and October. It would seem most probable that the +primary action in such cases was in the trades themselves, but it is by no +means certain that such is the case. This is the class of storms of which +Mr. Redfield has industriously investigated some twenty or more; Mr. Espy +some, and Lieutenant Porter two. Their course, when very violent, is often +more directly north than that of storms, however violent, which originate +north of the calms of Cancer, owing, perhaps, to their greater +paramagnetic character. This course I have myself observed, in several +instances, about the period of the autumnal equinox--never, however, more +southerly than from S. W. to N. E., on the parallel of 41°, except in +three, and, perhaps, four, instances, when it has been S. W. by S. to N. +E. by N. I know of no class of storms in relation to which the evidence of +primary action in the counter-trade is stronger than in those of the class +which originate on the ocean east of the Windward Islands. But it is not +satisfactory as to them. Doubtless the conflict of polarities between the +passing trades is sufficient to produce the showers and rains which are +ordinarily found over the ocean and lowlands, in the equatorial belt; but +it is doubtful whether it is sufficient to produce such extensive, +long-continued, and violent action, as that which characterizes the +hurricane autumnal gales. + +They occur, too, at the time when the whole machinery of distribution has +reversed its course, and is rapidly pursuing its journey south. It is a +period of great magnetic disturbance, over both land and sea; of more +active gales and local-increased precipitation. At the Magnetic +Observatory of Toronto, Canada West, these disturbances are carefully and +systematically observed, and their maxima, or periods of greatest +disturbance occur in April and September. (See Silliman's Journal, new +series, vol. xvii. p. 145.) + +The tendency to volcanic action is not as great at the autumnal, as at the +vernal equinox, for the reason that most of the volcanic action of the +western hemisphere develops itself now upon South rather than North +America. But both exist, and are active, and what are improperly termed +equinoctial storms, and gales, and rains, are proverbial during, or just +subsequent to, both periods with us--as they are when the same change, +called the breaking up of the monsoons, takes place in the line of +magnetic intensity, over southern and eastern Asia. A volume might be +filled with extracts, showing, at least, most remarkable coincidences +between violent volcanic action and great atmospheric disturbance. Perhaps +the increased fall of rain at and after the equinoxes, in the northern +hemisphere, and in certain localities subject to volcanic activity, is as +strikingly illustrated by the register, kept by Mr. Johnson, on the +volcanic Island of Kauai, one of the Hawaiian group, already alluded to, +as in any other case, although it is by no means a singular one. The +greatest fall of rain, in any month except April and October, was eight +inches. In April, the fall was fourteen inches, in October, eighteen +inches. Neither the equatorial, nor extra-tropical belt, were over the +island during those months; but they were the N. E. trades, and the result +was owing solely to the interposition of high volcanic mountains, _in a +state of disturbance_, into, or near, the strata of the counter-trade. Mr. +Dobson, in stating a theory to which we shall hereafter advert, advances +the following proposition: + +"7. _Cyclones (hurricanes) begin in the immediate neighborhood of active +volcanoes._ The Mauritius cyclones begin near Java; the West Indian, near +the volcanic series of the Caribbean Islands; those of the Bay of Bengal, +near the volcanic islands on its eastern shores; the typhoons of the China +Sea, near the Philippine Islands, etc." + +The peculiar stormy state of the atmosphere, over the Gulf Stream, to +which I have alluded, certainly affords no evidence of primary atmospheric +action. It is a body of south polar water, pursuing its way under the +guidance of magnetism--maintaining its polarity--arched somewhat like the +roof of a house, by the outward pressure of a cold north polar current +which it has met to the east of the Banks of Newfoundland, and forced to +take an in-shore course to the southward, and the bodies of water which +the rivers discharge, and a conflict with the north polar surface-winds +which sweep over it, and fogs, and thunder, and rain, are a matter of +course. Dr. Kane met a portion of this singular current in Baffin's Bay, +north of 75°, which had preserved its characteristics and a considerable +proportionate excess of heat, although it probably had been around +Greenland, or found its way to the west, toward the magnetic pole, through +some of its northern fiords or straits. (Grinnel Expedition, p. 120.) + +The investigations of Lieutenant Maury show, that when the Gulf Stream +turns to the eastward, crossing the lines of declination at right angles, +as the counter-trades also seem to do in the same latitude, it is _carried +up, in summer, several degrees to the north_, and descends again in +winter--thus demonstrating its connection with the shifting magnetic +machinery which controls alike the ocean, the atmosphere, and the +temperature of the earth.[7] + +There are other irregularities which deserve to be noticed, in this +connection, although the analogical evidence they afford is far from being +decisive. + +I have already said that it was within my own observation, that +alternating lines of heat and cold, as well as rain and drought, existed +frequently, without regard to latitude, following, to some extent, the +course of the counter-trade. Such lines have been observed by others. + +Thus, Mr. Espy, after describing a snow-storm, which was followed by a +very cold N. W. wind, of several days' continuance, says: + + "This cold air covered the whole country, from Michigan to the + eastern coast of the United States, till the beginning of the great + storm of the 26th January; and, what is worthy of particular notice + is, that _the temperature began to increase first in the north and + north-west_. On the morning of the 25th, in the north-western parts + of Pennsylvania, and northern parts of New York, the _thermometer_ + had already _risen in some places 30°_, and, in others, _above 40°_. + While in the S. E. corner of Pennsylvania, and in the S. E. corner of + New York it had not _begun to rise_. The _wind_ also began to change + from the _north-west_ to _south_ and _south-east_, _first_ in the + north-west parts of Pennsylvania and New York, some time before it + commenced in the south-east of those States; and, during the whole of + the 25th, the thermometer, in the north of New York, continued to + rise, though the wind was blowing from the southward, where the + thermometer was many degrees lower." + +Thus, too, Mr. Redfield (American Journal of Science, November, 1846, p. +329): + + "On the contrary, in times of the greatest depression of the + thermometer, in numerous instances, the cold period has been found to + have first taken effect in, or near, the tropical latitudes, and the + Gulf of Mexico, and has thence been propagated toward the eastern + portions of the United States, in a manner corresponding to the + observed progression of storms." + +This was because the cold N. W. wind which _followed_ storms began to +follow them as the storms curved and passed to the N. E. + +They occur in Europe also. Says Kämtz: + + "Such contrasts are not uncommon in Europe, and, in this respect, the + Alps form a remarkable limit; for they separate the climates of the + north of Europe from the Mediterranean climates, where the + distribution of rain is not the same as in the center of Europe. + Hence the differences between the climates of the north and south of + France. _If the winter is mild in the north_, the newspapers are + filled with the lamentations of the _Italians_ and _Provençals_ at + the _severity of the cold_." + +These facts seem to indicate a primary action in the counter-trade. +Probably in connection with one class of storms they do, and with another +do not. I shall endeavor to show the distinction when I come to the +classification of storms. + +The difference of seasons in this country, and over the entire northern +hemisphere, is often very great. In a remarkable work of a remarkable +man--"A Brief History of Epidemic and Pestilential Diseases," by Noah +Webster, published in 1799, 2 vols.--a history of the weather for about +two centuries--1600 to 1799 inclusive, is given generally, and then in a +tabular form. Those who think that every considerable extreme which occurs +exceeds any thing before known, will do well to consult that work. +Droughts are described, where "there was not a drop of rain for three or +four months, and cattle were fed upon the leaves of the trees." Winters, +so intensely cold that the thermometer fell to 20° below zero, at +Brandywine; or so mild that there was little frost, and people upon +Connecticut River plowed their fields, and the _peach trees blossomed in +Pennsylvania in February_. These extremes generally existed in Europe and +America at the same time, but occasionally they were opposite and +alternate. Says Mr. Webster, in summing up the facts (vol. ii. p. 12): "It +is to be observed that in some cases a severe winter extends to both +hemispheres, sometimes to one only, and in a few cases to a part of a +hemisphere only. Thus in 1607-8, 1683-4, 1762-3, 1766-7, 1779-80, 1783-4, +the severity extended to both hemispheres. In 1640-41, 1739-40, and in +other instances, the severe winter in Europe preceded, by one year, a +similar winter in America. In a few instances, severe frost takes place in +one hemisphere during a series of mild winters in the others; but this is +less common. In general, the severity happens in both hemispheres at once, +or in two winters, in immediate succession; and, as far as this evidence +has yet appeared, this severity is closely attendant on volcanic +discharges, with very few exceptions." + +It will be seen that Dr. Webster (LL.D. and not M.D., and therefore the +remarkable character of the work) attributes great influence to +earthquakes and volcanic action. Probably he is correct in this. The +present active volcanic action of the western hemisphere is nearly all +within the trade-wind region, from Mexico to Peru inclusive. The West +India islands are of volcanic origin, and the influence of volcanic action +is not confined to a concussion of the earth, or the eruption of mud and +lava. Its connection with magnetic action, and disturbance, is +unquestionable. But whether they operate to increase or diminish the +trades, and the extent to which they induce violent electric action and +storms within and without the tropics, is a question which further +observation must determine. The ripples of the ocean, compared by +Lieutenant Banvard to that of a "boiling cauldron, or such as is formed by +water being forced from under the gate of a mill-pond," are met with in +the vicinity of volcanic islands, where hurricanes and water-spouts +originate, and have been observed to precede storms, and be connected with +a falling barometer. But whether they are volcanic or magneto-electric, +it is difficult to determine. Dr. Webster remarks, as the result of +observation, during the 17th century, that earthquakes had a N. W. and S. +E. progression in the United States, and especially in New England. In a +recent article, Professor Dana has examined, with great ability, the +general and remarkable trending of coast lines, groups of islands, and +ranges of mountains, from N. E. to S. W. and from N. W. to S. E. (American +Journal of Science, May, 1847.) + +The line of magnetic intensity, which connects our magnetic pole with its +opposite, is now upon this continent nearly a N. W. and S. E. line, and +the pole is fast traveling to the west. It may, and probably will yet, be +established, that there is an intimate connection between the cause of +volcanic action within the earth, to which the upheaval of the N. W. and +S. E., and N. E. and S. W. ranges were due, and of magnetic action +without, and between both, and the cause of _the S. E. extension_ of our +summer storms and belts of showers and barometric _waves_, and the +_peculiar N. W. wind_. Our limits do not permit us to pursue the subject. + +Much influence upon the weather has been attributed to the spots upon the +sun. These spots are supposed to be breaks or openings in the luminous +atmosphere or photosphere of the sun, through which its dark nucleus body +is seen. Counselor Schwabe, of Dessau, has made them his study since 1826, +and has arrived at some singular results. They seem to be numerous--in +groups--and to appear periodically with minima and maxima of ten years. +As the result of his observations, from 1826 to 1850, he gives us the +following table and remarks: + + +-----------------------------------------------+ + | Year. | Groups. | Days showing | Days of | + | | | no spots. | Observation. | + |-------|---------|--------------|--------------| + | 1826 | 118 | 22 | 277 | + | 1827 | 161 | 2 | 273 | + | 1828 | 225 | 0 | 282 | + | 1829 | 199 | 0 | 244 | + | 1830 | 190 | 1 | 217 | + | 1831 | 149 | 3 | 239 | + | 1832 | 84 | 49 | 270 | + | 1833 | 33 | 139 | 267 | + | 1834 | 51 | 120 | 273 | + | 1835 | 173 | 18 | 244 | + | 1836 | 272 | 0 | 200 | + | 1837 | 333 | 0 | 168 | + | 1838 | 282 | 0 | 202 | + | 1839 | 162 | 0 | 205 | + | 1840 | 152 | 3 | 263 | + | 1841 | 102 | 15 | 283 | + | 1842 | 68 | 64 | 307 | + | 1843 | 34 | 149 | 312 | + | 1844 | 52 | 111 | 321 | + | 1845 | 114 | 29 | 332 | + | 1846 | 157 | 1 | 314 | + | 1847 | 257 | 0 | 276 | + | 1848 | 330 | 0 | 278 | + | 1849 | 238 | 0 | 285 | + | 1850 | 186 | 2 | 308 | + +-----------------------------------------------+ + + "I observed large spots, visible to the naked eye, in almost all the + years not characterized by the minimum; the largest appeared in 1828, + 1829, 1831, 1836, 1837, 1838, 1839, 1847, 1848. I regard all spots, + whose diameter exceeds 50", as large, and it is only when of such a + size that they begin to be visible to even the keenest unaided sight. + + "The spots are, undoubtedly, closely connected with the formation of + faculæ, for I have often observed faculæ, or narben, formed at the + same points from whence the spots had disappeared, while new solar + spots were also developed within the faculæ. Every spot is surrounded + by a more or less bright, luminous cloud. I do not think that the + spots exert any influence on the annual temperature. I register the + height of the barometer and thermometer three times in the course of + each day, but the annual mean numbers deduced from their observations + have not hitherto indicated any appreciable connection between the + temperature and the number of the spots. Nor, indeed, would any + importance be due to the apparent indication of such a connection in + individual cases, unless the results were found to correspond with + others derived from many different parts of the earth. If the solar + spots exert any slight influence on our atmosphere, my tables would, + perhaps, rather tend to show that the years which exhibit _a larger + number of spots_ had a _smaller number of fine days_ than those + exhibiting few spots." + +These observations _seem_ to show that the spots exert no influence upon +the weather, and to be satisfactory. But, perhaps, they are not entirely +so. No effect would, of course, be expected from day to day, and perhaps +the annual mean may not be seriously disturbed, and yet the spots may +seriously affect the seasons. Popular tradition has fixed upon certain +periods, of 10, 20, and 40 years, for the return of winters of unusual +severity; and the tables of Mr. Webster, and other facts, show that it is +not wholly without foundation. If we, and those we have cited, are not +mistaken in most of the views expressed, the natural effect of a partial +interception or failure of the sun's rays, by or from the existence of the +spots, would be to decrease the exciting power of the solar rays upon +terrestrial magnetism, and, as a consequence, the volume of the trades and +their amount of moisture. This would increase the _mean_ heat of the +summer in the temperate zone--for the _less_ the volume of trade, the less +precipitation and variable wind, and succeeding polar waves of cooler air, +and the greater mean heat. On the other hand, the same cause, and the +feebler heating power of the sun's rays, would make the winters more +severe, both from an absence of a portion of heat, derived directly from +the sun's rays, and a less mitigating influence, from the action of the +trade, by reason of its decreased volume. So, too, the absence of spots, +and a more powerful influence from the solar rays, may gradually carry +the machinery further north in summer, and further south in winter, and +thus make the _seasons extreme_ without seriously disturbing the mean of +the year. And both these may occur in a more marked degree over our +intense magnetic area than in Europe. I am satisfied that they do so +occur. That the partial failure of the sun's rays limits the transit of +the machinery, and the volume of the trades during the latter half of the +decade, and extends the transit and increases the volume during the first +half, producing an occasional severe summer drought and severe winter, in +the warmest portion of the decade. And that the variations correspond with +the difference in the character and number of the spots in different +decades, and hence the longer and shorter periods. + +Turning to the tables of Dr. Webster, we find that a general tendency to +extreme seasons does seem to exist from the 6th to the 10th year of every +decade, and especially of every alternate decade. The periods of 1707-8, +1728, 1737 and 1739, 1749-50, 1758-9, 1779-80, 1798-9, are those in which +the tendency was seen most decided. These tables are very general. The +thermometer was not perfected till about 1700, and did not get into +general use before 1750. There were very few meteorological registers +kept, or accessible to Dr. Webster. Hence he was obliged to resort to such +other sources of information as were open to him, and such statements as +he found are not always entirely reliable. The oldest inhabitant is apt to +express himself very strongly respecting present extremes, and fail +somewhat in his recollection of those which have past. Still his tables +afford general and obvious evidence of the regularity of those periodic +conditions. + + +---------------------------------------------------------+ + |A. D.| Summer. | Winter. | + |-----|-------------------------|-------------------------| + | 1701| hot and dry | .... | + | 1702| hot and dry | .... | + | 1703| .... | .... | + | 1704| dry Europe | .... | + | 1705| .... | .... | + | 1706| hot, dry Europe | .... | + | 1707| very hot | .... | + | 1708| .... | very severe | + | 1709| .... | .... | + | 1710| .... | .... | + | 1711| .... | cold Europe | + | 1712| wet England | .... | + | 1713| wet England | mild | + | 1714| dry and hot | .... | + | 1715| dry | .... | + | 1716| very dry | severe | + | 1717| .... | severe | + | 1718| hot and wet | .... | + | 1719| .... | cold America | + | 1720| dry Europe | .... | + | 1721| .... | .... | + | 1722| cold, wet | .... | + | 1723| .... | cold | + | 1724| wet England | .... | + | 1725| wet England | .... | + | 1726| .... | .... | + | 1727| dry, hot Amer. | .... | + | 1728| hot Amer. | severe Europe | + | 1729| .... | .... | + | 1730| .... | very cold Eng. | + | 1731| .... | .... | + | 1732| .... | severe Amer. | + | 1733| dry Eng. | .... | + | 1734| .... | .... | + | 1735| wet | .... | + | 1736| wet | .... | + | 1737| .... | very severe Am. | + | 1738| .... | .... | + | 1739| wet England | very severe Eng. | + | 1740| .... | very severe Am. | + | 1741| .... | .... | + | 1742| .... | severe Syria | + | 1743| hot | .... | + | 1744| .... | .... | + | 1745| .... | .... | + | 1746| .... | .... | + | 1747| hot and dry | severe | + | 1748| dry | .... | + | 1749| very dry | .... | + | 1750| very hot | very severe | + | 1751| wet England | severe Amer. | + | 1752| very hot Amer. | .... | + | 1753| .... | severe | + | 1754| .... | mild Amer. | + | 1755| .... | severe Europe | + | 1756| .... | severe Syria | + | 1757| .... | .... | + | 1758| hot | .... | + | 1759| .... | severe | + | 1760| .... | .... | + | 1761| very dry Amer. | .... | + | 1762| very dry Amer. | severe | + | 1763| .... | .... | + | 1764| hot Europe | .... | + | 1765| hot Europe | severe Europe | + | 1766| hot and dry Eur. | very severe | + | 1767| .... | cold | + | 1768| hot | .... | + | 1769| hot | .... | + | 1770| wet England | .... | + | 1771| wet Am. & Eng. | cold Europe | + | 1772| hot America | Am., great snow | + | 1773| .... | .... | + | 1774| .... | severe Europe | + | 1775| .... | .... | + | 1776| hot | severe Europe | + | 1777| .... | .... | + | 1778| hot | mild | + | 1779| hot Eng. | very severe | + | 1780| .... | .... | + | 1781| .... | .... | + | 1782| dry Amer. | .... | + | 1783| hot | very severe | + | 1784| hot | .... | + | 1785| dry Europe | cold | + | 1786| cool | cold | + | 1787| cool | .... | + | 1788| rainy Amer. | cold | + | 1789| cool spring, hot summer | severe Eur., mild Amer. | + | 1790| .... | .... | + | 1791| very hot Am. | cold | + | 1792| .... | .... | + | 1793| hot, dry Am. | mild Amer. | + | 1794| .... | severe Europe | + | 1795| Amer., hot, rainy | .... | + | 1796| Autumn very Dry Am. | cold Amer. | + | 1797| cool Am. | severe Amer. | + | 1798| very hot } | { long & severe | + | 1799| very dry Am. } | { Amer. & Eur. | + +---------------------------------------------------------+ + +Still more definite evidence is found in the meteorological tables of Dr. +Holyoke and Dr. Hildreth, and an account, by Dr. Hildreth, of the seasons +when the Ohio River was closed or obstructed by ice, found in Silliman's +Journal, new series, vol. xiii. p. 238. + +Thus, we have, from the tables of Dr. Holyoke, the following annual means, +from 1786 to 1825, inclusive. I have arranged them in periods of five +years. It will be seen that there are three peculiarities observable. +First, a marked difference between the first and second periods of the +decade, corresponding, generally, with the presence or absence of the +spots. Second, a difference in the mean of the decades which may well be +supposed to correspond with the difference in the number or size of the +spots since a like difference is observable in number and size, and the +time when they reached their maxima and minima, in the table of Schwabe. +And, third, there are occasional single cold years during the warm period, +and these correspond with what the tables of Dr. Webster show for both the +sixteenth and seventeenth centuries. In relation to this, it should be +remembered that volcanic action is a frequent and powerful disturber of +the regular action of terrestrial magnetism, and that the extremes, for +that reason, are frequently meridional or local and alternating; and to +that cause very great extremes, and marked exceptions, may be due, +notwithstanding the spots upon the sun may exert an influence in producing +hot summers and cold winters toward the close of each decade. Thus, to +select an instance to illustrate this and explain an anomaly: The coldest +season during the whole period, embraced in the following tables, is that +of 1812. This occurs during the decrease of spots, and the warm half of +the decade. Turning to the table of volcanic action, and of earthquakes, +found in the Report of the British Association for 1854, we find that year +was remarkable for earthquakes in the United States and South America. In +December, 1811, earthquakes commenced in the valley of the Mississippi, +Ohio, and Arkansas, felt also at places in Tennessee, Kentucky, Missouri, +Indiana, Virginia, North and South Carolina, Georgia, and Florida, though +not so severely east of the Alleghanies, _which continued until 1813_. +About the same time they commenced in Caraccas, and, in March, 1812, +became severe over the greater portion of the northern section of South +America, and in the Atlantic. No such general and continued succession of +earthquakes occurred during the other periods embraced in the tables, and +the mean of the following five years was very low, embracing the memorable +cold summer of 1816. + + +---------------------------------------------------------------+ + | Cold Period. | Warm Period. | Cold Period. | Warm Period. | + |---------------|---------------|---------------|---------------| + |1786 48°.53 |1791 48°.963|1796 48°.678|1801 50°.432| + |1787 47°.88 |1792 48°.44 |1797 48°.135|1802 50°.794| + |1788 47°.676|1793 50°.96 |1798 49°.471|1803 50°.24 | + |1789 47°.68 |1794 50°.768|1799 48°.291|1804 48°.328| + |1790 46°.53 |1795 50°.173|1800 49°.989|1805 50°.792| + |---------------|---------------|---------------|---------------| + |Mean of | | | | + |period 47°.659|Mean 49°.901|Mean 48°.910|Mean 50°.117| + |---------------|---------------|---------------|---------------| + |---------------|---------------|---------------|---------------| + |1806 47°.982|1811 50°.76 |1816 47°.113|1821 48°.15 | + |1807 48°.132|1812 45°.28 |1817 46°.277|1822 49°.81 | + |1808 49°.485|1813 47°.702|1818 48°.009|1823 47°.58 | + |1809 47°.92 |1814 48°.279|1819 50°.75 |1824 49°.25 | + |1810 49°.001|1815 47°.607|1820 48°.70 |1825 50°.99 | + |---------------|---------------|---------------|---------------| + |Mean 48°.505|Mean 47°.925|Mean 48°.169|Mean 49°.15 | + +---------------------------------------------------------------+ + +The tables of Dr. Hildreth, from 1826 to 1854, inclusive, furnish, +generally, evidence of a like character. There are, however, an anomaly or +two which will be observed. From 1826 to 1830, the mean is high during +the period when spots were at a maximum. But that maximum embraced a much +less number of spots than the two succeeding ones. A contrast appears in +the tables of Dr. Hildreth, during the early period, for Dr. Holyoke's +register, for 1827, puts it _below the mean_, but Dr. Hildreth's one of +the _highest of the half century_. In 1835 commenced a period when the +spots were much more numerous, and from 1835 to 1838, inclusive, the +seasons were correspondingly below the mean. From that period to 1844 a +gradual and slightly irregular rise took place, excepting the year 1843, +when another cold year intervened. The table of earthquakes, published by +the British Association, closes with 1842, and I have not access to any +others. The occurrence of such cold years, in the warm period, at +intervals during the two centuries previous, and in 1812, and onward, and +evidently owing to increased volcanic action beneath the western portion +of the northern hemisphere, justifies the belief that the low temperature +of 1843 was owing to the same cause. The following are the means from the +tables of Dr. Hildreth: + + +----------------------------------------------------------------+ + |1826 54°.00|1831 50°.87|1836 50°.03|1841 52°.18|1846 53°.64| + |1827 54°.92|1832 52°.42|1837 51°.57|1842 52°.83|1847 52°.00| + |1828 55°.22|1833 54°.56|1838 50°.62|1843 50°.77|1848 52°.50| + |1829 52°.38|1834 52°.40|1839 52°.54|1844 53°.25|1849 52°.09| + |1830 54°.93|1835 50°.65|1840 52°.35|1845 52°.73|1850 51°.48| + |------------|------------|------------|------------|------------| + |Mean 54°.29|Mean 52°.18|Mean 51°.52|Mean 52°.35|Mean 52°.32| + +----------------------------------------------------------------+ + +The observations of Dr. Holyoke were made at Salem, Massachusetts; those +of Dr. Hildreth at Marietta, Ohio. + +The following, in relation to the freezing of the Ohio River, is evidence +of a different kind, but shows the same general correspondence, and +particularly _the mildness of the winters when there were few spots_, and +their severity from 1836 to 1838, inclusive, when the spots were most +numerous: + + 1829.--River open all winter--some floating ice. + 1830.--River closed 27th January. + 1831.--Floating ice--closed 23d January--opened 20th February. + 1832.--Closed in December, which was a very cold month--opened January + 8, and remained open all winter. + 1833.--Open all winter. + 1834.--Open all winter. + 1835.--Closed January 6--opened the last of the month--cold. + 1836.--Closed 28th January--opened 25th February. + 1837.--Closed from 8th December to 8th February. Cold year. + 1838.--Closed from 13th January to 13th March. Cold year. + 1839.--Closed from 6th December to 13th January. + 1840.--Closed 29th December--opened 15th January. + 1841.--Closed 3d January--opened 8th do. + 1842.--Open all winter. + 1843.--Closed 28th November--opened 5th December--open all the rest of + the winter. + 1844.--Open all winter. + 1845.--Open all winter. + 1846.--Closed 5th December--opened again a few days--closed again on the + 26th. It is not stated how long it remained closed. + 1847.--Open all winter. + 1848.--Much floating ice, but not closed--heavy rains and floods. + 1849.--Floating ice in January, but not closed. + 1850.--Floating ice, but not closed. + 1851.--Open all winter--a little ice. + + (December in the above table, means December previous). + +This is more reliable as to the winter season than the tables of annual +means--although the evidence they afford, making due allowance for the +exceptions, is very striking. + +I shall return to this part of the subject again. + +But there is other evidence of the influence of these spots. Their +connection with the irregular magnetic disturbance of the earth has been +distinctly traced. Colonel Sabine, President of the British Association, +in his opening address, September, 1852, after reviewing the recent +discoveries in magnetism, says:-- + + "It is not a little remarkable that this periodical magnetic + variation is found to be identical in period, and in epochs of maxima + and minima, with the periodical variation in the frequency and + magnitude of the _solar spots_, which M. Schwabe has established by + twenty-six years of unremitting labor. From a cosmical connection of + this nature, supposing it to be finally established, it would follow + that the decennial period, which we measure by our magnetic + instrument, is, in fact, a solar period, manifested to us, also, by + the alternately increasing and decreasing frequency and magnitude of + observations on the surface of the solar disc. May we not have in + these phenomena the indication of a cycle, or period of _secular + change in the magnetism of the sun_, affecting visibly his gaseous + atmosphere or photosphere, and sensibly modifying the magnetic + influence which he exercises on the surface of our earth?"--American + Journal of Science, new series, vol. xiv. p. 438. + +I think it may fairly be inferred, that although these spots do not +occasion the "cold spells" and "hot spells," and other transient +peculiarities, they do materially affect the _mean_ temperature of the +year, and exert an obvious influence when at their maxima; and there is a +tendency to an increase of the heat and dryness of summer, and the +severity of winter, at the periods named, in our excessive climate, and a +well-established connection between the spots and magnetic disturbances +and variations. + +Popular opinion has ever attributed to the moon a controlling effect upon +the changes of the weather. If it be dry, a storm is expected _when the +moon changes_; or if it be wet, dry weather. Such popular opinions are +usually entitled to respect, and founded in truth. But every attempt to +verify _this opinion_, by careful observation and registration, has +failed. Weather-tables and lunar phases, compared for nearly one hundred +years, show four hundred and ninety-one new or full moons attended by a +change of the weather, and five hundred and nine without. The celebrated +Olbers, after _fifty years of careful observation_ and comparison, decided +against it. So did the more celebrated Arago, at a more recent +date--summing up the result of his observations by saying--"Whatever the +progress of the sciences, never will observers, who are trustworthy and +careful of their reputation, venture to foretell the state of the +weather." Still, the moon may influence the weather, though she may not +effect changes at her syzygies or quadratures, and this subject should not +be too summarily dismissed. That the moon can not effect changes at the +periods named seems philosophically obvious. She changes, for the _whole +earth_, within the period of twenty-four hours; yet, how varied the state +of things on different portions of its surface. The equatorial belts of +trades, and drought, and rains, cover from fifty to sixty degrees of its +surface, and know nothing of lunar disturbance. The extra-tropical belt of +rains and variable weather moves up in its season, uncovering 10°, or +more, of latitude, and admitting the trades and a six months' drought over +it, as in California, regardless of the moon. Under the zone of +extra-tropical rains, even upon the eastern part of the continent of North +America, "dry spells" and "wet spells" exist side by side; the focus of +precipitation is now in one parallel, and now in another--_storms_ exist +_here_ and _fair weather there_, on the same continent at the same time; +and as the moon's rays in her northing pass round the northern hemisphere +during the twenty-four hours, they, doubtless, pass from ten to thirty or +more storms, of all characters and intensities, moving in opposition to +her orbit--and as many larger intervening areas of fair weather, not one +of which are indebted to her for their existence, or "take thought of her +coming." + +The storm, which originates in the tropics, pursues its curving way now N. +W., then N. E., and again north, to the Arctic circle, and, perhaps, +around the magnetic pole, over gulf, and continent, and ocean, _occupying +one third the time of a lunation, and two changes, perhaps, in its +progress_, without any perceptible or conceivable influence from her. Yet +every inhabitant of mother-earth, influenced by _coincidences remembered_, +and uninfluenced by _exceptions forgotten_, looks up within his limited +horizon, and devoutly expects from the agency of some phase of the moon, a +change for the special benefit of his _dot_ upon the earth's surface. Upon +how many of these countless dots is the moon at a particular phase, or +relative distance from the sun, to change fair weather to foul, or foul to +fair? Upon none. The storms keep on their way;--the wet spells, and the +dry spells, the cold and the hot spells alternate in their time, and +though the moon turns toward them in passing, her dark face, her half +face, or her full orb (the gifts of the sun, which confer no power), they +do not heed her. They are originated, and are continued, by a more potent +agent. They are the work of an atmospheric mechanism, as _ceaseless_ in +its operation as _time_, as _regular_ as the _seasons_, _as extensive as +the globe_. + +Indeed, it seems as if it was expressly designed by the Creator that the +moon should not interfere materially with this atmospheric machinery. She +is the nearest orb; her influence would be controlling and continuous; +would follow her monthly path from south to north, and with changes too +violent, and intervals too long; and would interfere with the regular +fundamental operation in the trade-wind region, where she is _vertical_. +Aside from the attraction of gravitation, therefore, she seems to have +been so created as to be incapable of exerting any influence. She is +without an atmosphere; the rays which she reflects are polarized, and +without chemical or magnetic power; and, if it be true that Melloni has +recently detected heat in them, by the use of a lens three feet in +diameter, which could not previously be effected, its quantity is +exceedingly small, and incapable of influence. Doubtless, the attraction +of her mass is felt upon the earth, as the tides attest; and upon the +atmosphere as well as the ocean. But the atmosphere is comparatively +_attenuated_, and exceedingly so at its upper surface. Her attraction, +therefore, although felt, is not influential. She seemed, to Dr. Howard, +to produce in her northing and southing, a lateral tide which the +barometer disclosed, but owing to the attenuated character of the +atmosphere, neither the sun nor moon create an easterly and westerly tide, +that is observable, except with the most delicate instruments. Sabine is +believed to have detected such a tide by the barometer, at St. Helena, of +one four thousandth of an inch. But even this _infinitesimal influence_ +may prove an error upon further investigation. There is a diurnal +variation of the barometer, but it is not the result of her attraction, +for it is not later each day as are the tides, exists in the deepest mines +as well as upon the surface, and is demonstrably connected with the +_group_ of _diurnal_ changes produced by the action of the sun-light and +heat upon the earth's magnetism. + +Can the lateral tide, if there be one, affect the weather? for in the +present state of science it seems entirely certain that the moon can exert +an influence in no other way. + +If the received idea of many, perhaps most, meteorologists, on which all +wheel barometers are constructed, that a _high barometer_ necessarily +produces _fair weather_, and a _low one foul_, were true, she certainly +might do so. But that idea can not be sustained, and there is no known +certain influence exerted by the moon upon the weather, in relation to +which we have any reliable practical data. + +Humboldt appears to have adopted the impression of Sir W. Herschell, that +the moon aids in the dispersion of the clouds. (Cosmos, vol. iv. p. 502.) +But the tendency to such dispersion is always rapid during the latter part +of the day and evening, when there is no storm approaching, and the full +moon renders their dissolution visible, and attracts attention to them. +The Greenwich observations, also, carefully examined by Professor Loomis, +fail to confirm the impression of Herschell and Humboldt, and those +eminent philosophers are doubtless in this mistaken. + +From this general and somewhat desultory view of the general facts, which +bear analogically upon the question, no decisive inference can be drawn in +relation to the seat of the primary influence which produces the +atmospheric changes. The preponderance is in favor of the magnetic, or +magneto-electric, action of the earth. We must come back to our own +country and grapple with the question at home. + + + + +CHAPTER IX. + + +Before proceeding to do this, however, it may be well to look at some +theories which have been advanced, and to a greater or less extent +adopted, and at their bearing upon the question. + +The calorific theory is at present the prevailing one in Europe and in +this country. Meteorologists there and here refer all atmospheric +conditions and phenomena to the influence of heat. The principal +applications of that theory have been considered. But within the last few +years the elasticity and tension of the aqueous vapor of the atmosphere +have received much attention, as exerting an auxiliary or modifying +influence. Professor Dove, of Berlin, who ranks perhaps as the most +distinguished meteorologist of that continent, attributes barometric +variations to _lateral overflows_, and, in the upper regions, resulting +from the elevation of the atmosphere by expansion; and in this view +meteorologists of Europe seem generally to acquiesce. In an article sent +to Colonel Sabine, and recently republished in the American Journal of +Science, January, 1855, in thus attempting to account for the annual +variation of barometric pressure, which occurs in Europe and Asia, and, +indeed, over the entire hemisphere. He says: + + "From the combined action or the variations of aqueous vapor, and of + the dry air, we derive immediately the periodical variations of the + whole atmospheric pressure. As the dry air and the aqueous vapor + mixed with it, press in common on the barometer, so that the up-borne + column of mercury consists of two parts, one borne by the dry air, + the other by the aqueous vapor, we may well understand that as with + increasing temperature the air expands, and by reason of its + augmented volume rises higher, and _its upper portion overflows + laterally_," etc. + +And in another place he says: + + "From the magnitude of the variations in the northern hemisphere, and + the extent of the region over which it prevails, we must infer that + _at the time of diminished pressure a lateral overflow probably takes + place_," etc. + +Doubtless, the mean pressure of the atmosphere, in summer, in the northern +hemisphere, is less than in winter, in some localities, and greater in +others, and it differs in different countries of equal temperature. And +this is all very intelligible. The mean of the pressure for the month is +made up by _averaging_ all the _elevations_ and _depressions_. During a +month, showing a very low mean, the barometer may, at times, attain its +_highest altitude_, if the depressions below the mean are great or more +frequent. The barometer is depressed during storms, and ranges high during +_set fair_ weather. Ordinarily, therefore, the more stormy the season the +more diminished the mean pressure; and it is a mistake to look to an +overflow to account for the fact. The changes in the location of the +atmospheric machinery, and consequent change in the amount and severity of +falling weather, and the periodic frequency and character of storms, and +consequent _periodic_ depressions and elevations of the barometer, +explain the annual mean variations, as they do the other phenomena. But it +is perfectly consistent with the calorific theory to attempt to account +for these differences by another of those ever-necessary modifications, +viz.: the different tension and elasticity of aqueous vapor in different +countries of equal temperature; and then to _suppose_ an expansion of the +whole body of the atmosphere and a lateral overflow from the place where +the air is expanded, on to some other, where it is not; and thus _suppose_ +all necessary currents in the upper regions, setting hither and yon, by +the force of gravity alone. And apparently he who is best at supposition +becomes the most distinguished meteorologist. Perhaps I have already said +all that I ought to be pardoned for saying, in relation to the utter +absurdity of attributing all meteorological phenomena to the agency of +heat; but when I find such views as those which that article contains, +emanating from so distinguished a man, sanctioned by the President of the +British Association, and copied into the leading journal of science in +this country, I can not forbear a further and a somewhat critical +examination of them. There is more error of supposition and less truth in +it, than in any other article regarding the science, of equal length, +which has fallen under my notice. + +What is the height of this expansion? The moisture of evaporation ascends, +ordinarily, but a few thousand feet. The atmosphere grows regularly +cooler, from the earth to the trade, and _the increased warmth that is +felt at the surface extends but little way_. Currents of warm air do not +ascend. The strata maintain, substantially, their relative positions; and +this is a most beneficent provision. In northern latitudes of the +temperate zone, all the warmth derived from a few hours' sunshine is +needed at the surface; and, deplorable, indeed, would be our condition, if +the atmosphere, as fast as warmed by the rays of the sun, were to hasten +up, and the frigid strata descend in its place. The earth would not be +habitable. All the warm air on its surface would be rising as soon as it +became warmed, and the cold air above be descending, and enveloping us +with the chilling strata which are ever floating within two or three miles +above us. No. Infinite wisdom has ordered it otherwise. The laws of +magnetism and of static-electric induction and attraction keep the strata +in their places, and preserve to us the warmth which the solar rays afford +or produce. The inhabitant of the valley, in a high northern latitude, in +summer, can plant, and sow, and reap, at the base of the mountain whose +summit penetrates the stratum of continual congelation, and up its sides, +almost to the line of perpetual snow; and, as he looks upon the fruits of +his labor, and up to the snow-clad peak that towers above him, can thank +his Maker for placing a warm equatorial current, a perpetual barrier, +between the fertility and warmth which surround him, and the cold +destructive strata above; and thank Him for not creating such a state of +things, as certain meteorologists insist we shall believe He has created. +Again, where are the _upper regions_, from which the lateral overflow +takes place? The atmosphere is differently estimated, at from thirty to +forty-five miles, or more, in height. Whatever its height may be, it is +exceedingly attenuated in its "upper regions." + +Gay-Lussac marked the barometer at 12-95/100 inches at the height of +23,040 feet. Two thirds of the atmospheric density, then, is within five +miles of the earth. Air, too, is _compressible_. Allowing for the latter +and the attenuation, how many miles in vertical depth, of its "_upper +regions_," must move from one portion to another, to depress the barometer +two inches--its range sometimes in twenty-four hours--or even half an +inch? Let the computation be made, and see how startling the proposition, +how utterly impossible that the theory can be true. + +The distinguished Professor, in the paper referred to, introduces his +theory of the formation of hurricanes, and we quote-- + + "If we suppose the upper portions of the air ascending over Asia and + Africa to flow off laterally, and if this takes place suddenly, it + will check the course of the upper or counter-current above the + trade-wind, and force it to break into the lower current. + + "An east wind coming into a S. W. current must necessarily occasion a + rotatory movement, turning in the opposite direction to the hands of + a watch. A rotatory storm, moving from S. E. to N. W., in the lower + current or trade, would, in this view, be the result of the encounter + of two masses of air, impelled toward each other at many places in + succession, the further cause of the rotation (originating primarily + in this manner) being that described by me in detail in a memoir 'On + the Law of Storms,' translated in the 'Scientific Memoirs,' vol. iii. + art. 7. Thus, it happens that the West India hurricanes, and the + Chinese typhoons occur near the lateral confines on either side of + the great region of atmospheric expansion, the typhoons being + probably occasioned by the direct pressure of the air from the region + of the trade-winds over the Pacific, into the more expanded air of + the monsoon region, and being distinct from the storms appropriately + called by the Portuguese 'temporales,' which accompany the out-burst + of the monsoon when the direction of the wind is reversed." + +The analogy between this, and a theory of Mr. Redfield's, will be noticed +further on. But I remark, in passing, that there is not a fact or +inference in this paragraph which will bear examination. + +1. There is no such regular S. W. wind over the surface trade, as he +supposes. Doubtless, there are, occasionally, secondary S. W. currents +between the counter-trade and the surface one, with partial condensation, +for much of both becomes depolarized by their reciprocal action and +precipitation, and these induced S. W. currents are sometimes so strong as +to usurp the place of the surface-trade, and become very violent in the +latter part of hurricanes; but such is not the usual course of the upper +currents of the West Indies, as the progress of storms there, and +observation, prove. + +2. There can not be any _periods_ of extensive and _sudden_ expansion over +Africa. If there is any place on the earth which has a more uniformly +progressive temperature, either way, and is more free from _sudden_ +extremes, or which is more arid and destitute of aqueous vapor, and sudden +aqueous expansions, than another, it is Africa. No such occasional sudden +expansions are there possible. + +3. Winds do not, and can not, "_encounter_." They stratify upon each +other. They are produced by the action of opposite electricity, and are +_connected together_ in their origin and action. The atmosphere is never +free from the regular and irregular currents, however invisible for the +want of condensation. Aeronauts find them in the most serene days. They +exist without encounter or tendency to rotation, every where, and at all +times; even over the head of the distinguished Professor, whether he +sleeps or is awake. We can all see them when there is condensation, and it +is rarely the case that there is not some degree of it in some of them. + +4. That "Great region of expansion" is a chimera. It does not exist. It is +a region of _lower temperature_, and of _condensation_, instead of +_expansion_ of _aqueous vapor_. The trade does not rise in it, or the S. +W. wind overflow from it. See the table cited page 165. + +5. The hurricanes do not originate _in the surface trades_, as he +supposes. They originate in the belt of rains, the supposed "region of +expansion," and issue out of it; or in the counter-trade, where volcanic +elevations rise far into or above the surface trade. + +6. This hypothesis can not be sustained upon his own principles. The +distance between Africa and the West India Islands, where most of the +hurricanes originate, is from 2,500 to 3,000 miles. These gales are small +when they commence, not ordinarily over one or two hundred miles in +diameter, and often less. There are trades all the way over from Africa, +and S. W. winds also, if they exist, as he supposes, in the West Indies. +How can it happen that this lateral overflow should pass _without effect_, +over 2,500 miles of S. W. wind and trade, and concentrating the overflow +of a continent over one small and chosen spot of the West Indies, _pitch +down_ there, and there only, and crowd the S. W. wind into the trade +below? This is too much for sensible men to believe. + +What does Professor Dove mean by the term _impulsion_, as applied to the +winds? How are they _impelled_? It is the fundamental idea of his +calorific theory, that they are _drawn_ by the _suction_ caused by a +_vacuum_, and the vacuum created by expansion and overflow above, in +obedience to the law of gravity; that the S. E. trade is drawn to the +great region of expansion, and the S. W. runs from it as an overflow. But +if the S. W. is driven down into the plane and place of the +surface-trades, how does it continue to be impelled, and why is it not +then subject to the suction of the vacuum which draws the trade? Does that +vacuum _select its air_, and so attract the trade, in preference to the +depressed portion of the S. W. current, that the former runs around the +latter to get to the vacuum, and the latter around the former to get away +from it? And does the trade, when it has got around the S. W. current, +instead of going to the vacuum, continue to gyrate, and the S. W. current, +instead of pursuing its regular course, gyrate also about the trade, and +both move off together, regardless of the vacuum of the great region of +expansion, in a new direction to the N. W., in an independent, +self-sustaining, cyclonic movement, increasing in power and extent, +involving extended and increasing condensation, producing the most violent +electrical phenomena, and thus continuing up, even to the Arctic circle? +Yes, says Professor Dove. No, say all fact, all analogy, and his own +principles. + +7. His theory relative to the typhoons is unintelligible. If they +originate near the lateral confines of the great region of atmospheric +expansion, they originate in the region of the trade-winds, for the two +are identical. How the direct pressure of the air from the trade-wind over +the Pacific, in the more expanded air of the monsoon region, can occasion +a typhoon upon any principles, passes my comprehension. If, as Lieutenant +Maury supposes, the monsoons are reversed trades, then the trade-wind and +monsoon region are identical. If the monsoons are found in the belt of +rains, then, the trades, upon Professor Dove's principles, pass into the +monsoon region by attraction or suction, without pressure. Either way the +theory is undeserving of consideration. + +A new theory has recently been started by Mr. Thomas Dobson, and, although +it is (like all other efforts to get the _upper strata down_ to produce +condensation, or those below _up_, that they may be condensed), without +foundation, his collection of facts is brief and interesting. I copy his +article from the London, Edinburgh, and Dublin Phil. Mag., for December, +1853. It adds to the collection of facts in relation to the connection +between volcanic action and storms for the seventeenth century, made by +Dr. Webster: + + The following appear to be the main facts which are available as a + basis for a theory which shall comprehend all the meteors in + question: + + 1st. The eruption of a submarine volcano has produced water-spouts. + + "During these bursts the most vivid flashes of lightning continually + issued from the densest part of the volcano, and the volumes of smoke + rolled off in large masses of fleecy clouds, gradually expanding + themselves before the wind in a direction nearly horizontal, and + drawing up _a quantity of water-spouts_."--(Captain Tilland's + description of the upheaval of Sabrina Island in June, 1811, Phil. + Trans.) + + With this significant fact may be compared the following analogous + ones: + + "In the Aleutian Archipelago a new island was formed in 1795. It was + first observed _after a storm_, at a point in the sea from which a + column of smoke had been seen to rise."--(Lyell, Principles of + Geology.) + + "Among the Aleutian Islands a new volcanic island appeared in the + midst of _a storm_, attended with flames and smoke. After the sea was + calm, a boat was sent from Unalaska with twenty Russian hunters, who + landed on this island on June 1st, 1814."--(Journal of Science, vol. + vii.) + + "On July 24th, 1848, a submarine eruption broke out between the + mainland of Orkney and the island of Strousa. Amid thunder and + lightning, a very dense jet black cloud was seen to rise from the + sea, at a distance of five or six miles, which _traveled toward the + north-east_. On passing over Strousa, the wind from a slight air + became _a hurricane_, and a thick, well-defined belt of large + hailstones was left on the island. The barometer fell two + inches."--(Transactions Royal Society, Edinburg, vol. ix.) + + 2d. Hurricanes, whirlwinds, and hailstones accompany the paroxysms of + volcanos. + + "1730. A great volcanic eruption at Lancerote Island, and _a storm_, + which was equally new and terrifying to the inhabitants, as they had + never known one in the country before."--(Lyell, Principles of + Geology, vol. ii.) + + "1754. In the Philippine Islands a terrible volcanic eruption + destroyed the town of Taal and several villages. Darkness, + hurricanes, thunder, lightning, and earthquakes, alternated in + frightful succession."--(Edinburgh Philosophical Journal.) + + "In 1805, 1811, 1813, and 1830, during eruptions of Etna, caravans in + the deserts of Africa perished by violent whirlwinds. In 1807, while + Vesuvius was in eruption, a whirlwind destroyed a caravan."--(Rev. W. + B. Clarke in Tasw. Journal.) + + "1815, Java. A tremendous eruption of Tombow Mountain. Between nine + and ten P.M., ashes began to fall, and soon after _a violent + whirlwind_ took up into the air the largest trees, men, horses, + cattle, etc."--(Raffles' History of Java.) + + "1817, Dec. Vesuvius in eruption. In the evening _a hail storm_, + accompanied with red sand."--(Journal of Science, vol. v.) + + "1820, Banda. A frightful volcanic eruption, and in the evening an + earthquake and a violent hurricane."--(Annales de Chimie.) + + "1822, Oct. Eruption of Vesuvius. Toward its close the volcanic + thunder-storm produced an exceedingly violent and abundant fall of + rain."--(Humboldt, Aspects of Nature.) + + "1843, Jan. Etna in eruption. Violent hurricanes at Genoa, in the Bay + of Biscay, and in Great Britain. + + "1843, Feb. Destructive earthquakes in the West Indies, a volcanic + eruption at Guadaloupe, followed by hurricanes in the Atlantic." + + "1846, June 26. Volcano of White Island, New Zealand, in eruption. + Heavy squalls of wind and hail; it blew as hard as in a + typhoon."--(Commodore Hayes, R.N., in Naut. Mag., 1847.) + + "1847, March 20. Volcanic eruption and earthquake in Java; and on the + 21st of March, and 3d of April, violent hurricanes."--(Java Courant.) + + "1851, Aug. 5. A frightful eruption of the long dormant volcano of + the Pelée Mountain, Martinique. Aug. 17. Hurricane at St. Thomas, + etc.; earthquake at Jamaica, etc. + + "1852, April 14. Earthquake at Hawaii, and on the 15th a great + volcanic eruption. On the 18th _a gale of unusual violence_ lasted + thirty-six hours, and did great damage."--(The Polynesian, April 22, + 1852.) + + 3d. In volcanic regions, earthquakes and hurricanes often occur + almost simultaneously, but in no certain order, and without any + volcanic eruption being observed. + + In 1712, 1722, 1815, and 1851, earthquakes and hurricanes occurred + together at Jamaica; in 1762 at Carthagena; in 1780 at Barbadoes; in + 1811 at Charleston; in 1847 at Tobago; in 1837 and 1848 at Antigua; + in 1819, an awful storm at Montreal, rain of a dark inky color, and a + slight earthquake. People conjectured that a volcano had broken out. + In 1766 the great Martinique hurricane, a _waterspout_ burst on Mount + Pelée and overwhelmed the place. Same night, an earthquake. + + 1843, Oct. 30. Manilla.--Twenty four hours' rain and two heavy + earthquakes. 10 P.M., a severe hurricane. + + "1852, Sept. 16. Manilla--An earthquake destroyed a great part of the + city; many vessels wrecked by a great hurricane in the adjacent seas, + between the 18th and 26th of September."--(Singapore Times.) + + "1731, Oct. Calcutta.--Furious hurricane and violent earthquake; + 300,000 lives lost." + + "1618, May 26. Bombay.--Hurricane and earthquakes; 2,000 lives + lost."--(Madras Lit. Tran., 1837.) + + "1800. Ongole, India, and in 1815, at Ceylon, a hurricane and + earthquake shocks."--(Piddington.) + + "1348. Cyprus.--An earthquake and a frightful hurricane."--(Hecker.) + + "1819. Bagdad.--An earthquake and _a storm_--an event quite + unprecedented. + + "1820, Dec. Zante.--Great earthquake and hurricane, with + manifestations of a submarine eruption."--(Edinburg Phil. Journal.) + + "1831, Dec. Navigator's Islands.--Hurricane and + earthquakes."--(Williams' Missionary Enterprise.) + + "1848, Oct., Nov. New Zealand.--Succession of earthquake shocks, and + several tempests. + + "1836, Oct. At Valparaiso, a destructive tempest and severe + earthquakes."--(Nautical Magazine, 1848.) + + When an earthquake of excessive intensity occurs, as at Lisbon, in + 1755, the volcanic craters, which act as the safety-valves of the + regions in which they are placed, are supposed to be sealed up; and + it is a remarkable and highly-suggestive fact, that _no hurricane + follows such an earthquake_. The number of instances of the + concurrence of ordinary earthquakes and hurricanes might easily be + increased, but the preceding suffice to show the _generality_ of + their coincidence, both as _to time_ and place. + + 4th. The breaking of water-spouts on mountains sometimes accompanies + hurricanes. + + In 1766, during the great Martinique hurricane, before cited. + + "1826, Nov. At Teneriffe, enormous and most destructive water-spouts + fell on the culminating tops of the mountains, and a furious cyclone + raged around the island. The same occurred in 1812 and in + 1837."--(Espy and Grey's Western Australia.) + + "1829. Moray.--Floods and earthquakes, preceded by water-spouts and a + tremendous storm."--(Sir T. D. Lander.) + + "1826, June. Hurricanes, accompanied by water-spouts and fall of + avalanches, in the White Mountains."--(Silliman's American Journal, + vol. xv.) + + 5th. The fall of an avalanche sometimes produces a hurricane. + + "1819, Dec. A part (360,000,000 cubic feet) of the glacier fell from + the Weisshorn (9,000 feet). At the instant, when the snow and ice + struck the inferior mass of the glacier, the pastor of the village of + Randa, the sacristan, and some other persons, _observed a light_. A + frightful hurricane immediately succeeded."--(Edinburg Philosophical + Journal, 1820.) + + 6th. Water-spouts occur frequently near active volcanos. + + This is well known with regard to the West Indies and the + Mediterranean. The following notices refer to the Malay Archipelago + and the Sandwich Islands: + + "Water-spouts are often seen in the seas and straits adjacent to + Singapore. In Oct., 1841, I saw _six_ in action, attached to one + cloud. In August, 1838, one passed over the harbor and town of + Singapore, dismasting one ship, sinking another, and carrying off the + corner of the roof of a house, in its passage landward."--(Journal of + Indian Archipelago.) + + "1809. An immense water-spout broke over the harbor of Honolulu. A + few years before, one broke on the north side of the island (Oahu), + washed away a number of houses, and drowned several + inhabitants."--(Jarves' History of Sandwich Islands.) + + 7th. Cyclones begin in the immediate neighborhood of active volcanos. + + The Mauritius cyclones begin near Java; the West Indian, near the + volcanic series of the Caribbean Islands; those of the Bay of Bengal, + near the volcanic islands, on its eastern shores; the typhoons of the + China Sea, near the Philippine Islands, etc. + + 8th. Within the tropics, cyclones move toward the west; and, in + middle latitudes, cyclones and water-spouts move toward the N. E., in + the northern hemisphere, and toward the S. E. in the southern + hemisphere. + + 9th. In the northern hemisphere, cyclones rotate in a horizontal + plane, in the order N. W., S. E.; and in the southern hemisphere, in + the order N. E., S. W. + + By applying the principles of electro-dynamics to the electricity of + the atmosphere, I shall endeavor to connect and explain the preceding + well-defined facts. The continuous observations of Quetelet, on the + electricity of the atmosphere, from 1844 to 1849 (Literary Journal, + February, 1850), show that it is always positive, and increases as + the temperature diminishes. It therefore increases rapidly with the + height above the earth's surface. We may, consequently, regard the + upper and colder regions of the atmosphere as an immense reservoir of + electric fluid enveloping the earth, which is insulated by the + intermediate spherical shell formed by the lower and denser + atmosphere. Now, whenever a vertical column of this atmosphere is + suddenly displaced, the surrounding aqueous vapor will be immediately + condensed and aggregated, and the cold rarefied air and moisture will + form a vertical conductor for the descent of the electrical fluid. + This descent will take place down a spiral, gyrating in the order N. + W., S. E., in the northern hemisphere, since the electric current is + under the same influence as that of the south pole of a magnet; and + in the order N. E., S. W., in the southern hemisphere. The air + exterior to the conducting cylinder will partake of the violent + revolving motion, and a tornado or cyclone will be produced. + +Upon the foregoing facts I shall comment in another place. + +Three theories have been advanced by meteorologists of this country, two +of which profess to explain all the phenomena of the weather. Professor +Espy attributed the production of storms and rain to an ascending column +of air, rarefied by heat, and the rarefaction increased by the latent heat +of vapor given out during condensation, and an inward tendency of the air, +from all directions, toward the ascending vortex, constituting the +prevailing winds. Thus, Professor Espy conceived, and to some extent +proved, that the wind blew inward, from all sides, toward the center of a +storm, either as a circle, or having a long central line, and he conceived +that it ascended in the middle, and spread out above; and that clouds, +rain, hail, and snow, were formed by condensation consequent upon the +expansion and cooling of the atmosphere, as it attained an increased +elevation. + +_This ascent_ was not, in fact, _proved_ by Professor Espy, _has not been +found by others_, and _is not discoverable, according to my observations_. +The theory was ingenious, founded on the theory of Dalton, that the vapor +was maintained in the atmosphere by reason of a large quantity of latent +heat, which was given out when condensation took place. This theory is +also unsound. No such elevation of temperature is found in clouds or fogs +when they form near the earth, however dense. Thus the two principal +elements of Professor Espy's theory are found to be untrue, and the theory +untenable. But it was sustained with great ability and research, and the +distinguished theorist deserves much for the discovery and record of +important facts in relation to the weather. Aside from its theoretical +views, his book contains a great mass of valuable information, and will +well repay the cost of purchase and perusal. + +Another theory, by Mr. Bassnett, is of recent date, founded on the +influence of the moon, and the supposed creation of vortices in the ether +above, whose influence extends to the earth, producing storms and other +phenomena. No one can peruse his book without conceding to him great +ability and scientific attainment; and if his theory was true, the periods +of fair and foul weather could be calculated with great mathematical +certainty. But it contains inherent and insuperable objections. I will +only add that all herein before contained is in direct opposition to it. + +Mr. W. C. Redfield, of New York, as early as 1831, first advanced in this +country the theory of gyration in storms, and investigated their lines of +progress on our coast and continent. His theory is limited in its +character, and does not profess, except indirectly, to explain all, or +indeed any, of the other phenomena of the weather. As far as it goes, +however, it is generally received in this country and Europe, and has +been adopted by Reed, Piddington, and others, who have written on the law +of storms. The position of Mr. Redfield is honorable to himself and his +country. Science and navigation are much indebted to him for his industry +in the collection of facts. Nevertheless, his theory is not in accordance +with my observation, and I deem it unsound. Although expressed disbelief +of the theory has been characterized as an "attack" upon its author, I +propose, with that _respect_ which is due to him, but with that _freedom_ +and _independence_ which a search for _truth_ warrants, to examine it with +some particularity. It is a part of the subject, and I can not avoid it. + +When the theory was first announced, I adopted it as probably true; and +being then engaged in a different profession, which took me much into the +open air by night and day, I watched with renewed care the clouds and +currents for evidence to confirm it. I discovered none; on the contrary, I +found much, very much, absolutely and utterly inconsistent with its truth. +The substance only of these observations will be adduced. + +Mr. Redfield admits that the progression of our storms in the vicinity of +New York, is from some point between S. S. W. and W. S. W., to some point +between N. N. E. and E. N. E. According to my observation, except perhaps +in occasional autumnal gales, they are not often, if ever, from S. of S. +W., and the great majority of them, including, I believe, all N. E. +storms, are between S. W. and W. S. W. Now, the card of Mr. Redfield, +moving over any place from any point between S. W. and W. S. W., calls for +a S. E. wind at its axis, an E. wind at its north front, and a S. wind at +its south front, and does not call _for a N. E. wind on its front at all, +except at the north extreme_, where it could _not continue for any +considerable period_. + + +[Illustration: Fig. 17.] + + +In relation to this, I observe, 1st. _About one-half of our N. E. storms, +including some of the most severe ones, not only set in N. E., but +continue in that quarter without veering at all, during the entire period +that the storm cloud is over us_; usually for twenty-four hours; not +unfrequently for forty-eight hours, sometimes for seventy-two or more +hours. This every one can observe for himself, and it can not, of course, +be reconciled with his theory. + +2d. N. E. storms, whether they set in from that quarter in the +commencement, or veer to it afterward, when they do "change" round, more +frequently veer by the S. to the S. W. in clearing off, than back through +the N. into the N. W. The former, in accordance with his theory, they can +not do, as the reader can see by passing the left side of the card over +his place of residence on the map from S. W. to N. E. + +3d. N. E. storms often pass off without hauling by S. or backing by N., +and with or without a clearing off shower, the _wind shifting and coming +out suddenly at S. W._ This they could not do in accordance with his +theory, as slipping the card will show. + +4th. From June to February it is _exceedingly uncommon_ for a N. E. storm +to back into the N. W. They do so more frequently from February to May, +especially about the time of the vernal equinox and after; and then, +because the focus of precipitation and storm intensity of the extra +tropical zone of rains is S. of 42° east of the Alleghanies. His theory +requires them to back by N. into N. W. _in all cases, when they set in N. +E._ + +5th. When they do back from the N. E. into the N. W., it rarely indeed +continues to storm after the wind leaves the point of N. E. by N., and +generally, if it does continue stormy, _the wind is light_, and not a +gale, how violent soever the gale from the eastward may have been. +Usually, by the time the wind gets N. W., it has cleared off. This, Mr. +Redfield, as we shall see, evades by embracing the N. W. fair wind as a +part of the same gale. According to my observation, therefore, a _very +large proportion_ of the _N. E. storms_, and they are a majority of the +most violent ones of our climate east of the Alleghanies, do not +_commence, continue_, or _veer_ in accordance with his theory, but the +_reverse_; and so long as this is so, I can not receive his theory as +true. + +6th. S. E. storms do not always, or indeed often, conform to the +requirements of his card. When they set in violently at S. E., and +continue so for hours without veering, the axis of the storm should be +over us, and the wind should change _suddenly_ to N. W. This did not occur +in the storm of Sept. 3, 1821, nor does it often, if ever, occur in the +summer or early gales of the autumnal months. In the later storms of +autumn, and as often in those which are very gentle as any, and in the +winter months when S. E. gales are rare, it does sometimes so change after +the storm cloud has passed. But in the winter months, as in the storm +investigated by Professor Loomis, the storms are frequently long from S. +E. to N. W., and the S. E. wind blows nearly in coincidence with its long +axis, for a thousand or fifteen hundred miles, till the barometric minimum +is passed, and the inducing and attracting force of this part of the storm +cloud is spent, and then the N. W. wind follows; sometimes blowing in +under the storm cloud, turning the rain to snow; but oftener following the +storm within a few hours, or the next day. The storm of Professor Loomis, +when over Texas, was not probably more than four or five hundred miles in +length. As it curved more, and passed north and east, it extended +laterally, its center traveling with most rapidity, and when it reached +the eastern coast was about fifteen hundred miles long, and not more than +six hundred broad. Along the eastern part of that storm, except when by +its more rapid progress the front projected much further eastward over New +England than its previously existing line, the S. E. winds blew. When it +bulged out, so to speak, by reason of the increased progress of the +center, the wind veered to the N. E. The center of the storm passed near +St. Louis and south of Quebec, as the _fall of rain_, the _bulging_ of the +_rapidly-moving center_, and the _line of subsequent cold_, attest. It is +utterly impossible for any unbiased mind to look at the description of +that storm, and attribute to it a rotary character. With all the data +before him, Mr. Redfield himself has not attempted it directly.[8] + +The September storm of 1821 was more violent in character than any which +have since occurred. My recollection of it is as distinct as if it +occurred yesterday. Peculiar circumstances, not important in this +connection, fixed my attention upon the weather during that day and night. +There were cirro-stratus clouds passing all day, from about S. W. to N. +E., thickening toward night with fresh S. S. W. wind and flocculent scud, +such as I have since seen at the setting-in of S. E. autumnal gales. In +the evening the wind (in the immediate neighborhood of Hartford, Ct.), +veered to S. E., the cloud floated low, it became very dark, and the wind +blew a most violent gale. The trees were falling about the house where I +then resided, the windows were burst in, and I was up and observant. When +the cloud passed off to the east, it was suddenly light, and almost calm. +The western edge of the storm cloud was as perpendicular as a steep +mountain side, and was enormously elevated, and very black. I have +sometimes seen the western side of a summer thunder cloud, which had drawn +a violent gust along beneath it, as elevated and perpendicular, but never +a storm cloud. No cloud of that _depth_, or _intensity_ as exhibited by +its peculiar blackness, ever floated or will float so near the earth, +without inducing a devastating current beneath. After it had passed the +ridges east of the Connecticut valley, its top could be seen for a long +and unusual period over the elevated ranges. + +Now that storm was but an _intense portion_ of an extensive stratus-rain +cloud. Such portions frequently exist, and Mr. Redfield admits the fact. +Another like portion, in the same storm, passed over Norfolk, Virginia, +and the adjacent section, where the wind was N. E., and veered round by N. +W. to S. W. Baltimore, and some vessels at sea, were between the two +intense portions of the storm, and were not affected by either. Its +northern limit was bounded by a line, drawn from some point not far north +of Trenton, New Jersey, north-eastward, and north of Worcester, +Massachusetts. I was about forty miles south of its northern limit, and +north of its center. During that day, and the next, there was wind from +S. W. to S. E., inclusive, including the gale, and _from no other +quarter_. It did not at any time veer to the W. or N. W. After the passage +of the storm-cloud, the wind was very light. When this intense portion of +the storm passed over the valley of the Connecticut, its longest axis was +from S. S. E. to N. N. W., and the _wind was S. E. the whole length of +it_. In its passage from the longitude of Trenton to Boston, there was N. +W. wind at one point, and but one, and that was in the iron region, at the +N. W. corner of Connecticut, at the northern limit of the intense cloud, +and owing, doubtless, to some local cause. The direction of the wind in +that storm was in accordance with what is generally true of our storms. +The wind on the front of the storm depends upon its shape. If the storm is +long in proportion to its width (and no other _violent_ autumnal or winter +storm has been investigated, to my knowledge), the wind blows axially, or +obliquely, on its front. Thus, if long from S. E. to N. W., the wind on +its front will blow from the S. E. So, if the storm is long from S. W. to +N. E., and has a south-eastern lateral extension, with an easterly +progression, the wind will blow axially in the center, and obliquely at +the edges. Instances might be multiplied, but I refer to one of recent +date and striking character. All of us remember the drought of 1854. It +ended in drenching rain on the 9th of September. This rain fell from a +belt, half showery and half stormy in character, which had a S. E. lateral +extension. + +The evening of the previous day there was some lightning visible at the +north, and the usual S. S. W. afternoon wind _continued fresh after +nightfall_. The next day we had a brisk wind from the same quarter, and, +after noon, the clouds appeared to pile up in the far north, seeming very +elevated. They continued to do so, extending southerly during the +afternoon, _with a high wind from S. S. W._, the cumulus clouds moving E. +N. E. At 5 P.M., gentlemen who left New York at 3 P.M., reported that a +dispatch had been received from Albany, dated 1 P.M., stating that it was +raining very heavily there. About 7 P.M., the belt reached us, and it +rained heavily from that time till morning. Not far from 8 P.M., and +during the heaviest rain, the wind shifted from the S. S. W. to N. E., and +blew fresh and cold from that quarter during the night, and till the belt +had passed south, and then from N. E. by N., cool, with heavy scud, during +the forenoon, veering gradually to the N. N. E., and dying away. After the +rain ceased, the northern edge of the belt was distinctly visible in the +S. and S. E., its stratus-cloud moving E. N. E., and its scud to the +westward. + +The front of that storm did not pass over us. It was long and narrow. The +wind blew somewhat obliquely inward, along its southern border, to the +eastward, and, in like manner, to the westward, on its northern border, +but from the N. E. axially along its central portions. + +In the last instance, the wind changed from S. W. to N. E. This, too, is +impossible, according to Mr. Redfield's theory. Similar instances, in +summer, and early autumn, are not uncommon. But I shall recur to this in +connection with the different _classes_ of storms. + +Again, the manner in which these S. E. winds co-exist with the N. E., and +become the prevailing wind, toward the close of the storm, is instructive, +and inconsistent with the theory of Mr. Redfield. In the West Indies, the +first effect of the storm is to increase the N. E. trade; the wind then +becomes baffling, but settles in the N. W. or N. N. W., _in direct +opposition to the admitted progress of the storm_. At this point, or at S. +W., it blows with most force. Sometimes it veers gradually, and sometimes +falls calm, and comes out from the S. W., blowing violently. It ends by +veering to the S. E., following gently the course of the storm. Thus, Mr. +Edwards, in the third volume of his History of Jamaica, as herein before +cited, "_all hurricanes begin from the north, veer back to W. N. W., W., +and S. S. W., and when they get round to S. E. the foul weather breaks +up_." + +A short, sudden gale, resembling those of our summer thunder-showers, is +sometimes met with from the S. E.; but the violent hurricanes of any +considerable continuance are, in almost every case, as just stated. + +Now, there is, in our latitudes, an obvious law on the subject, and it is +this:--If the storm is not disproportionately long, northerly and +southerly, there is a general tendency to induce and attract a surface +current, in opposition to the course of the storm on its front, and +especially its north front. At the same time, there is a tendency to +induce a lateral current on its side, particularly the southerly side, and +sometimes its south front: that the latter current is, in the first part +of the storm, above the former; in the middle and latter part, it becomes +the prevailing current at the surface, and the wind changes accordingly, +with or without a calm--that this lateral change sometimes takes place on +either side, but usually occurs on the side where the water is warmest, or +there is, for other and local reasons, a _greater susceptibility in the +atmosphere to inductive and attractive influence_. Thus, our N. E. storms +very frequently have a southerly current also, drawn from the ocean, south +of us, which forms the middle current, and, in the middle and latter part +of it, becomes the prevailing one. _I have seen more than a hundred such +instances, clearly and distinctly marked._ Since I have been writing this +chapter, January 29th, 1855, such an instance has occurred. On Sunday, the +28th, the cirro-stratus were all day passing from the S. W. to N. E., and +gradually thickening with light air from the E. N. E., in the afternoon. +During the evening the wind set in _violently_ from the N. E., with a +deluging rain. During the night, and after a brief calm, it changed +suddenly to the southward, and blew in like manner. This morning the storm +was gone, and with it, six inches of hard, frozen icy snow; the trade was +clear, with the exception of here and there a broken, melting piece of +stratus, but scud were still running from the southward, and the wind has +been from the south, veering to S. W., all day, with sunshine. As I have +before remarked, this middle current is always present, in this locality, +in stratus storms, when there is a heavy fall of rain or snow, although, +when the latter happens, the middle current is sometimes from the +northward; if it be from the southward, it turns the snow first into very +large flakes, and then to rain in our part of the storm. + +Doubtless, the same thing occurs every where. In the West Indies, and +especially over the Leeward Islands, the middle current is most commonly +from the stream of warm water which runs off to the westward into the +Caribbean Sea; as the S. W. moonsoon is from the same current below the +Cape de Verdes. The S. W. winds, which come from those south polar waters, +in the West Indies, appear to be the most violent. But it may be on either +or both sides. + +The hurricane cloud of the West Indies moves confessedly N. W. in most +instances, and undoubtedly it does in all. There is an immutable law that +requires it. The seeming exceptions are not such; they are but instances +imperfectly investigated. Now, a circular storm moving N. W. can set in N. +W. only on the left front, and _can not change to S. W. on that side of +the axis_. Nor can the wind blow at the axis from N. W. at all. It should +be N. E. in first half, and S. W. in last half. Strange as it may seem, +the axis of a West India hurricane in conformity with Mr. Redfield's +theory, and a N. W. progression, has never been found, with perhaps a +single exception, in any one of which I have seen a description. On the +west coast of Europe, the gale is commonly from the Atlantic, either +following under the storm from the S. W., or blowing in diagonally from +the W. or N. W.; the N. E. wind of western Europe being a cold, dry wind, +which there is reason to believe has been around the Siberian pole and is +returning, as the cold northerly winds of the North Pacific have around +the North American magnetic pole. "If the N. E. winds always prevailed," +says Kämtz, speaking of Berlin, "even at a considerable height it would +never rain." This was based on an observation of showers, and not fully +reliable. But the dry and cool character of the N. E. wind of western +Europe is unquestionable. The S. E. wind is also a storm wind, but owing +to the character of the surface from which it is attracted, it is not as +violent as the westerly winds are. + +Such, too, is the general course and character of the side wind in the +southern hemisphere. There gales are less frequent, the magnetic intensity +is less, the counter-trades are less; it is not in "the order of +Providence" that as much rain shall fall there. Nevertheless, gales occur, +although rarely, if ever, with equal violence. About New Holland, where +storms are pursuing a S. E. course, they have the wind N. E., +corresponding to our S. E., veering from thence, _by the north_, to the +westward, clearing off from S. W., with a rising barometer, as ours do +from N. W. + +In the Bay of Bengal, the Indian Ocean, and the Arabian Sea, there is more +irregularity. + +But the law of progress and lateral winds can be distinctly traced as +_present_ and prevailing, notwithstanding the irregularities. Our limits +do not permit an analysis. In the celebrated case of the Charles Heddle, +there was much evidence to show that she was driven across the front of +the storm by one lateral wind, and back by another. (Diagram of Colonel +Reid, p. 206.) + +The waters of the Indian Ocean are hot and confined. Storms there are +often composed of detached masses, move slower--sometimes not more than +three or four miles an hour--and they curve over the ocean, where it is +hotter than in any similar latitude. Yet, notwithstanding all +peculiarities and irregularities, the law we have been considering is +probably the _prevailing_ law there. + +No man knows better the existence of these different currents than Mr. +Redfield. Doubtless it has escaped his attention that the upper of two, +after the passage of a considerable proportion of the storm, becomes the +lower, and causes a seeming change of the same wind. + +In a series of elaborate articles, substantially reviewing the whole +subject, published in the American Journal of Science, for 1846, he says: + + "In nearly all great storms which are accompanied with rain, there + appear two distinct classes of clouds, one of which, comprising the + storm scuds in the active portion of the gale, has already been + noticed. Above this is an extended stratum of stratus cloud, which is + found moving with the general or local current of the lower + atmosphere which overlies the storm. It covers not only the area of + rain, but often extends greatly beyond this limit, over a part of the + dry portion of the storm, partly in a broken or detached state. This + stratus cloud is often concealed from view by the nimbus, and scud + clouds in the rainy portion of the storm, but by careful + observations, may be sufficiently noticed to determine the general + uniformity of its specific course, and, approximately, its general + elevation. + + "The more usual course of this extended cloud stratum, in the United + States, is from some point in the horizon between S. S. W. and W. S. + W. Its course and velocity do not appear influenced in any + perceptible degree by the activity or direction of the storm-wind + which prevails beneath it. On the posterior or dry side of the gale, + it often disappears before the arrival of the newly condensed cumuli + and cumulo-stratus which not unfrequently float in the colder winds, + on this side of the gale." + + "The general height of the great stratus cloud which covers a storm, + in those parts of the United States which are near the Atlantic, can + not differ greatly from one mile; and perhaps is oftener below than + above this elevation. This estimate, which is founded on much + observation and comparison, appears to comprise, at the least, the + limit or thickness of the proper storm-wind, which constitutes the + revolving gale. + + "It is not supposed, however, that this disk-like stratum of + revolving wind is of equal height or thickness throughout its extent, + nor that it always reaches near to the main canopy of stratus cloud. + It is probably higher in the more central portions of the gale than + near its borders, in the low latitudes, than in the higher, and may + thin out entirely at the extremes, except in those directions where + it coincides with an ordinary current. Moreover, in large portions of + its area, there may be, and often is, more than one storm-wind + overlying another, and severally pertaining to contiguous storms. In + the present case, we see, from the observations of Professor Snell + and Mr. Herrick, at Amherst, Massachusetts, and at Hamden, Maine (115 + and 135 b.), that the true storm wind, at those places, was + super-imposed on another wind; and various facts and observations may + be adduced to show that brisk winds, of great horizontal extent, are + often limited, vertically to a very thin sheet or stratum." + +Much of the foregoing is graphically described, and unquestionably true. +But it may well be asked how he, or others, distinguish which of two or +more currents (for there are frequently three, and sometimes four +visible), are the true currents of the storm, and which interlopers from +another storm? Is the true one always the upper one, and why? If the +upper one, why is the interloper at the surface noted and quoted to prove +what a storm is? How does he know what proportions of the winds he has +recorded to show the revolving motion of gales, were the true storm winds +of the particular storm? or, that every one of them was not an interloping +wind on which the true storm wind was superimposed? + +These inquiries are pertinent, for obviously, unless some rule for +distinguishing between the currents is given, and there be evidence of +direct observation to show that the surface wind, whose direction is +noted, is the true wind of the storm, and that the _latter_ is not +_superimposed_, no reliance can be placed upon logs, or newspaper +accounts, or registers. There is another element besides direction, viz.: +superimposition, a determination of which _is_ essential to _truth_. It +will be difficult for Mr. Redfield to say that a determination of that +element has been made, with certainty, in a single storm he has +investigated; and in relation to the convergence of storms, and blending, +and superimposition of their winds, I think he is mistaken. + +Mr. Redfield is right in saying (American Journal of Science, vol. ii., +new series, p. 321) that "too much reliance may be placed upon mere +observations of the surface winds in meteorological inquiries," and yet +_they_ only have thus far been regarded, and he has proved gyration in no +other way. I have frequently, with a vane in sight, asked intelligent men +how the wind was, and been amused and instructed by their inability to +state it correctly. Mr. Redfield, in his inquiries, often found two +reports of the weather at the _same time_, from the _same place_, +materially different; and I have known, from my own observation, +newspapers and meteorological registers to be several points out of the +way; and this, because the vanes are influenced by local elevations, and +change several points, and very often; because few know the exact points +of the compass in their own localities, and because entire accuracy has +not been deemed essential. For these reasons, newspaper and telegraphic +reports are not always reliable; and therefore, and because, also, +storm-winds are easterly and fair winds westerly, and the former veer from +east around to west, on one or both sides in many cases, there are few +storms which can not be represented as whirlwinds, by a proper _selection_ +of _reports_, a corresponding _location_ of the _center_, and an +_extension_ of the lines of supposed gyration, so as to include the +_preceding_ winds, the actual winds of the storm, and the _lateral_, and +_succeeding_ fair weather ones. + +But, again, Mr. Redfield is right in saying there is, in such cases, "an +extended stratum of stratus cloud," and it is always present. But why does +he say this _covers the storm_? Is it distinct from it, and if so, what is +it doing there? What power placed it there, and for what purpose? Has this +extended stratum of cloud, which forms the canopy of a vast chamber--five +hundred to one thousand miles in diameter, and less than two miles in +vertical depth, while the earth forms the floor--any agency in producing +the whirl that is supposed to be going on within it, and if so, what? Has +the earth any agency, and if so, what? If neither the ceiling nor floor of +the chamber have any agency in producing it, what does? Are we to consider +the _storm-scud_ as possessing the power, and as waltzing around the +aerial chamber, carrying the air with them in a hurricane-dance of +devastation? _What, in short, is the power, and how is it exerted?_ + +To these questions, Mr. Redfield's essays furnish no comprehensive answer. +There is an intimation that the cause of storms will be, at some future +day, developed. One attempt, and but one, has thus far been made, and that +I quote entire: + + "We have seen that the two Cuba storms, as well as the Mexican + northers, have appeared to come from the contiguous border of the + Pacific Ocean. + + "Now, are there any peculiarities in the winds and aerial currents of + those regions, which may serve to induce or support a leftwise + rotation in extensive portions of the lower atmosphere, while moving + on, or near the earth's surface? I apprehend there are such + peculiarities, which have an extensive, constant, and powerful + influence. First, we find on the eastern portion of the Pacific, from + upper California to near the Bay of Panama, an almost constant + prevalence of north-westerly winds at the earth's surface. Next, we + have an equally constant wind from the southern and south-western + quarter, which, having swept the western coast of South America, + _extends across the equator to the vicinity of Panama_, thus meeting, + and commonly over-sliding the above-mentioned westerly winds, and + tending to a deflection or rotation of the same, from right to left. + As this influence may thus become extended to the Caribbean or + Honduras Sea, we have, next, the upper or S. E. trade of this sea, + which is here frequently a surface-wind, and must tend to aid and + quicken the gyrative movement, ascribed to the two previous winds; + and lastly we have the N. E. or lower trade, from the tropic, which, + coinciding with the northern front of the gyration, serves still + further to promote the revolving movement which may thus result from + the partial coalescence of these great winds of Central America, and + the contiguous seas. + + "Thus, while a great storm is, in part, on the Pacific Ocean, its N. + E. wind may be felt in great force on that side of the continent, + through the great gorges or depressions near the bays of Papagayo or + Tehuantepec, as noticed by Humboldt, Captain Basil Hall, and others, + the elevations which there separate the two seas being but + inconsiderable; and, when the gyration is once perfected, the whole + mass will gradually assume the movement of the predominant current, + which is generally the higher one, and will move off with it, + integrally, as we see in the cases of the vortices, which are + successively found in particular portions of a stream, where subject + to disturbing influences." + +The analogy between this and the theory of Professor Dove, cited above, +and prior, in point of time, is obvious. They are substantially alike in +principle, with different locations. They differ also in this, Professor +Dove appears to think something more than over-sliding necessary, and +assigns the duty of crowding the upper current down in to the lower, to +make an _encounter_, to a lateral overflow from Africa. Mr. Redfield seems +to think there may be a tendency to deflection when they "over-slide" each +other. They are both closet hypotheses, the poetry of meteorology, with +something more than poetical license as to facts. + +In the first place, _no such concurring winds exist in the same locality +at the same time_. When the inter-tropical belt of rains is over Central +America and Southern Mexico, a S. W. monsoon blows in under it, but it +usurps the place of all other surface winds; and, when the belt is absent, +that portion of the eastern Pacific is most remarkably calm, or is covered +by the N. E. trades. Secondly, the _trade-winds every where pursue their +appointed course without "tendency to deflection" by the meeting, or +"over-sliding," or "breaking in," or "encounter,"_ of other winds. The +great laws of circulation do not admit of any such _confusion_. And, +lastly, _no storm ever came over the eastern United States from that +quarter_. The unchangeable laws of atmospheric circulation forbid it. +Recent observations also have shown that the storms on the west coast of +Central America, and the eastern Pacific, pursue a N. W. course, precisely +as in the West Indies, and every where over the surface-trades of the +northern hemisphere. Indeed _Mr. Redfield himself has recently +investigated several of them, and admits their course to be +north-westerly_. (See American Journal of Science, new series, vol. xviii. +p. 181.) + +But, suppose the co-existence of the winds and the course of the storms +admitted as claimed, let us seek for clearer views. What do these +gentlemen mean? Do they intend to have us believe the air has inherent +moving power, and that the "tendency" of which they speak is an attribute +of the winds, and that when they thus meet, and "come into each other," +"encounter," or "over-slide," and become acquainted, they wheel into a +waltz, and move off northward, "integrally," with unceasing circular +movement, even until they arrive at the Arctic circle? Or is it a mere +mechanical effect of meeting, "coming into each other," or "over-sliding?" +If the latter, why a tendency to rotation from right to left? The +trade-winds, at least, are _continuous, unbroken sheets_, and not +disconnected portions which meet and blow past each other, and there is no +warrant for placing them _side and side_, and attributing to them any +such mechanical effect, and as little respecting the other winds. Outside +of the fanciful hypothesis, there are no facts to show such a tendency one +way rather than the other; and, in accordance with the known facts +regarding stratification of the currents of air, no such "tendency" can +exist. + +But what _power_ impels the winds, which thus meet at these points? If +they be impelled, is it consistent with the action of this power that the +_winds_ it has _created_ and _controls_, should thus assume an _opposite +"tendency,"_ and whirl away to the north-eastward, regardless of the power +that originated and controls them? What must this "_tendency_" be, which +thus _occasionally_ not only diverts the winds from the _usually regular +course_ given them by their originating power, but increases their action, +from gentle, ordinary winds, to hurricanes? Nay, which gives them a new, +resistless gyratory and electric energy, increasing as the new, +independent, supposed cyclonic organization moves off, "_integrally_," +away from "the home of its many fathers," on a devastating journey towards +the north pole? + +And, further, if all this were true as to the West Indies and Central +America, what is to be said of the billions of other storms, originating +on a thousand other portions of the earth's surface, and how are they to +be accounted for, inasmuch as such other "meetings," "coming into each +other," and "over-sliding," and "tendency to deflection," is not assumed +to exist? + +These questions cannot be satisfactorily answered. The distinguished +theorists are mistaken. The stratus-cloud does not over-lie or cover the +storm. IT IS THE STORM. The winds beneath, whether surface or +superimposed, are but its incidents, due to its static induction and +attraction. Their _direction_ depends on the shape of the storm cloud, and +its course of progression, and the susceptibility of the surface +atmosphere in this direction or that, to its inductive and attractive +influence. Their _force_ to its depth, its contiguity to the earth, and +the intensity of its action; and the scud, are but patches of +condensation, occasioned by the same inductive action which affects and +attracts the surface current in which they form. + +Another objection to Mr. Redfield's theory of gyration is based upon the +fact that in order to constitute his _storm_, to get the _gyration_, he +has to include, at least, an equal amount, generally a great deal more, of +_fair weather_. The N. W. wind, the "posterior, or dry side of the gale," +as he calls it (in the foregoing extract), is a _fair weather wind_. It is +_necessary_, however, to complete the supposed _circle_, and it is +_pressed into the service_. The practical answer given to the question, +"_what are storms?_" is, they are cyclones, part storm, so called, and +_part fair weather_; that is, the stratus-cloud, the scud, the easterly +wind, and rain or snow of day before yesterday, were the _wet side_, or +front part of the storm, and the sunshine, clear sky, and N. W. wind of +yesterday, to-day, and, perhaps, to-morrow, are the posterior or dry side. +When a storm clears off from the N. W. it is not _over_, it is, perhaps, +_just begun_; and, inasmuch as it storms again, very soon after the wind +changes back from the N. W. to the southward, in winter, our weather then +is pretty much all _storms_. + +The statement of this claim seems so absurd that it may appear like +injustice to make it. But gyration can not be made out without it, and it +is evident in the extract quoted above; in the claim that the winter +northers of the Mexican Gulf are parts of passing storms; and clearly and +unequivocally advanced as a distinct proposition, as follows: + +"1. The body of the gale usually comprises an area of rain or foul +weather, together with another, and, perhaps equal, or greater, area of +fair or bright weather." (Am. Jour. of Science, vol. xlii. p. 114.) + +Now, in the first place, we must distinguish between a storm and fair +weather, before we can tell what the former is, and it is difficult to +assent to a theory which explains what a S. E. storm of _twelve hours'_ +continuance is, by including _two or three days of succeeding N. W. fair +weather wind_, as a part of it. There is no proportionate relation as to +_time_, nor any relation as to _qualities_, or the attending conditions of +the atmosphere, nor any conceivable _connection_, except the hypothetical +one of _gyration_, between the two winds. + +And, in the second place, it is true, and Mr. Redfield is well aware of +the fact, that winds often blow for many days from the N. E., S. W., or N. +W., without any preceding or succeeding winds to which they have any +discoverable relation. If, therefore, truth would justify Mr. Redfield in +including the fair weather wind, a difficulty would remain which his +theory does not cover or explain. + +No American, except Mr. Redfield, has been able to discover satisfactory +evidence of the gyration of storms, by actual careful observation, or a +careful unbiased collation of the observation of others. Professor Coffin +is reported to have read to the Scientific Association, at their Buffalo +meeting, a paper, confirmatory, in part, but I have not been able to see +it. The tracks of tornados have been searched as with candles. When they +have been narrow, from forty to eighty rods, their action has been +substantially similar, and, although, as we have herein before stated, +some irregularities have been found which were consistent with +gyration--for irregularities attend the violent action of all forces, and +particularly the motion of electricity through the atmosphere, as every +one who has seen the zig-zag course of a flash of lightning knows--yet the +evidence of two lateral inward currents, or lines of force, has +predominated over all others. In all cases, where the path is narrow, +those lateral currents are the actors; they constitute the tornado; their +_irregularities_ of action produce the exceptions; but the exceptions are +neither numerous nor uniform, and do not prove either the theory of Mr. +Espy or that of Mr. Redfield. The action is not that of moving air, +merely, but of a power exceeding in force that of powder, which nothing +but electricity or magnetism can exert. As the path widens, the wind +becomes more like the straight-line gust which follows beneath the +ordinary severe thunder-showers. His theory finds no substantial +confirmation or support in the path of the tornado. + +Several storms were investigated by Professor Espy, some of them the same +which Mr. Redfield had attempted to show were of a rotary character; one +or two by the Franklin Institute of Philadelphia; one by Professor Loomis, +already alluded to; and recently, two by Lieutenant Porter, from logs +returned to the National Observatory. None of these investigations confirm +the theory of Mr. Redfield. Indeed, Mr. Redfield himself has found it +necessary to resort to suppositions of _modifying causes_ to explain the +evident inconsistencies. It is assumed that the axis, or center, +oscillates, and describes a series of circles; and thus, one class of +difficulties is avoided. Again, it is assumed that simultaneous storms +converge and blend upon the same field, and another class of difficulties +are surmounted. And, again, inasmuch as it is notorious that violent gales +are rarely if ever felt with equal violence around the area of a circle, +but from one or two points only, it is assumed, that the storm winds +ascend, superimpose, and descend again, when they return to the place of +their first violent action, etc. The _simple truth_ requires no such +resort to _modifying hypothesis_. + +Still, another objection is, that the changes in the barometer, which +occur before, during, and after storms, do not sustain the claims of Mr. +Redfield or the requirements of his theory. + +The barometer sometimes rises before storms. It generally commences +falling about the time, or soon after the storm sets in, continues to fall +during its progress, and rises again, sooner or later, afterward. This is +the general rule. + +On this subject Mr. Redfield's claim is this: + + "EFFECT OF THE GALE'S ROTATION ON THE BAROMETER.--The extraordinary + fall of the mercury in the barometer, which takes place in gales or + tempests, has attracted attention since the earliest use of this + instrument by meteorologists. But I am not aware that the principal + cause of this depression had ever been pointed out, previously to my + first publication in this journal, in April, 1831, when I took the + occasion to notice this result as being obviously due to the + _centrifugal force_ of the revolving motion found in the body of the + storm. + + "Since that period, inquiries have been continued by meteorologists + in regard to the periodical and other fluctuations of the barometer, + and the relations of these fluctuations to temperature and aqueous + vapor. But these incidental causes of variation, in the atmospheric + pressure, prove to be of minor influence, and we are left to the + sufficient and only satisfactory solution of this marked phenomenon + which is found in the centrifugal force of rotation." + +The average pressure of the atmosphere, at the surface of the ocean, or in +the interior of the country, allowing for elevation, is about equal to the +weight of a column of quicksilver, thirty inches in height; hence the +barometer is said to stand at about thirty inches at the level of the sea. + +This is sufficiently accurate for the northern hemisphere, north of the N. +E. trades; but the average is somewhat lower in the trades and in the +southern hemisphere. Thus, the average of sixteen months, during which the +Grinnell expedition was absent, was 30.08/100. + +From a large number of logs examined by Lieutenant Maury, the mean +elevation in the N. E. trades of the Atlantic was 29.97/100; the S. E. +trades of the Atlantic, 29.93/100; off Cape Horn, 29.23/100; S. E. trades +of the Pacific, 30.05/100; N. E. trades of the Pacific, 29.96/100. The +height of the barometer off Cape Horn is not a fair index of the general +elevation of the southern hemisphere, inasmuch as it stands lower there +than at the coast of Patagonia and Chili, or at most, if not all, other +stations in that hemisphere. + +As the barometer is constantly oscillating up and down (irrespective of +its diurnal oscillation), it has no known fair weather standard. The point +of 30 inches is taken only as it is a mean. I have known it to commence +storming when the barometer was at 30.70, and not to fall before it +cleared off, below 30.30. And I have known it to be below 30 for several +days consecutively, with fair weather. In our climate there is no reliable +fair weather standard for the barometer. It falls below 30 without +storming; it rises far above, and storms without falling below. No +reliance can be placed upon its elevation, except by comparison; but of +that hereafter. + +The general rule, nevertheless, is, that it falls more or less during +storms, whatever its height, and rises sooner or later, more or less, +after they clear off. + +The difference between its highest and lowest points is called its range. +The greatest range observed, and recorded, is about 3 inches--from about +28 to 31--but this range is rare. The range, in the trade-wind region, is +comparatively small; in this country it is greater than in Europe; and, +generally, the range will be found greatest where the volume of +counter-trade, and magnetic intensity, and the corresponding amount of +precipitation, and extremes of heat and cold are greatest. One of the +greatest ranges during one storm, or two successive portions of a storm, +in this country, which I have seen recorded, occurred at Boston, in +February, 1842. It was as follows--counting the hours as 24, and from +midnight: + + Feb. 15..10h..30.36. + " 16..13h..28.47 fall of 1.89 in 27 hours. + " 17..19h..30.39 rise of 1.92 in 30 hours. + " 18.. 2h..30.39 stationary 5 hours. + " 19.. 2h..29.46 fall of 0.93 in 24 hours. + " 20.. 2h..30.43 rise of 0.97 in 24 hours. + Amount of oscillation, 5.71 in 4 days, 11 hours. + +These ranges were owing to the alternation of S. E. storms, and N. W. +winds. + +Taking the first range as a basis, and allowing the height of the +atmosphere to be 1,100 feet for the first inch, we have nearly 2,000 feet +displaced during one day, if we look for the displacement near the earth, +or some 30 or 35 miles, if we soar aloft in the upper regions to look for +the _lateral overflow_ of Professor Dove, and about the same quantity +restored the next. This brings us to the inquiry, how was it done? It is +perfectly idle to talk about _difference_ of _temperature_ or _tension_ of +_vapor_, the _ascent_ of warm air, or _descent_ of cold in a case like +this; or to say that they were occasioned by a lateral overflow of some +thirty miles of its upper portion, first this way and then that, in such a +brief space of time. The change is equal to nearly 1/15 of the weight of +the whole atmosphere, and the cause, whatever it was, existed within two +or three miles of the earth. Mr. Redfield's explanation I give in his own +words, at length: + + "One of the most important deductions which may be drawn from the + facts and explications which are now submitted, is an explanation of + the causes which produce the fall of the barometer on the approach of + a storm. This effect we ascribe to the centrifugal tendency or action + which pertains to all revolving or rotary movements, and which must + operate with great energy and effect upon so extensive a mass of + atmosphere as that which constitutes a storm. Let a cylindrical + vessel, of any considerable magnitude, be partially filled with + water, and let the rotative motion be communicated to the fluid, by + passing a rod repeatedly through its mass, in a circular course. In + conducting this experiment, we shall find that the surface of the + fluid immediately becomes depressed by the centrifugal action, except + on its exterior portions, where, owing merely to the resistance which + is opposed by the sides of the vessel, it will rise above its natural + level, the fluid exhibiting the character of a miniature vortex or + whirlpool. Let this experiment be carefully repeated, by passing the + propelling rod around the exterior of the fluid mass, in continued + contact with the sides of the vessel, thus producing the whole + rotative impulse, by an external force, analagous to that which we + suppose to influence the gyration of storms and hurricanes, and we + shall still find a corresponding result, beautifully modified, + however, by the quiescent properties of the fluid; for, instead of + the deep and rapid vortex before exhibited, we shall have a concave + depression of the surface, of great regularity: and, by the aid of a + few suspended particles, may discover the increased degree of + rotation, which becomes gradually imparted to the more central + portions of the revolving fluid. The last-mentioned result obviates + the objection, which, at the first view, might, perhaps, be + considered as opposed to our main conclusion, grounded on the + supposed equability of rotation, in both the interior and exterior + portions of the revolving body, like that which pertains to a wheel, + or other solid. It is most obvious, however, that all fluid masses + are, in their gyrations, subject to a different law, as is + exemplified in the foregoing experiment; and this difference, or + departure from the law of solids, is doubtless greater in aëriform + fluids than in those of a denser character. + + "The whole experiment serves to demonstrate that such an active + gyration as we have ascribed to storms, and have proved, as we deem, + to appertain to some, at least, of the more violent class; must + necessarily expand and spread out, _by its centrifugal action, the + stratum of atmosphere subject to its influence, and which must, + consequently, become flattened or depressed by this lateral movement, + particularly toward the vortex or center of the storm_; lessening + thereby the weight of the incumbent fluid, and producing a consequent + fall of the mercury in the barometrical tube. This effect must + increase, till the gravity of the circumjacent atmosphere, superadded + to that of the storm itself, shall, by its counteracting effect, have + produced an equilibrium in the two forces. Should there be no + overlaying current in the higher regions, moving in a direction + different from that which contains the storm, the rotative effect + may, perhaps, be extended into the region of perpetual congelation, + till the medium becomes too rare to receive its influence. But + whatever may be the limit of this gyration, its effect must be to + _depress_ the _cold stratum_ of the upper atmosphere, particularly + toward the more central portions of the storm; and, by thus bringing + it in contact with the humid stratum of the surface, to produce a + permanent and continuous stratum of clouds, together with a copious + supply of rain, or a deposition of congelated vapor, according to the + state of the temperature prevailing in the lower region." + +The italics in the foregoing extract are mine; and, in relation to it, I +observe: + +1st. There is no cylindrical vessel around storms, and _air will not thus +resist air_. Confessedly, such resistance is necessary. Let any one watch +his cigar smoke, and see how readily it moves on, with little momentum. +Let any one try the experiment of creating a whirl in the _open air_, or +in a room, or box of paper, or other material, which can be suddenly +removed, with air colored by smoke. I am exceedingly mistaken if he does +not find the presence of a "cylindrical vessel," absolutely essential to +prevent the instantaneous tangential escape of the air. + +2d. Turn back to page 3 and look at the fall of the barometer in the polar +regions (recorded in the extract from Dr. Kane), with _scarcely any +wind_, and _as little variation_ in its _direction_, and see how utterly +Mr. Redfield's theory fails to account for the phenomena. + +3d. If I understand Mr. Redfield correctly, he has abandoned the claim as +originally made, that the wind moves in circles, expanding, and _spreading +out_ by a "_lateral movement_," and now asserts that it blows spirally +inward, and elevates the air in the center. I quote: + + "VORTICAL INCLINATION OF THE STORM WIND.--By this is meant some + degree of involution from a true circular course. In the New England + storm above referred to, this convergence of the surface-winds + appeared equal to an average of about 6° from a circle. In the + present case, such indication seems more or less apparent in the + arrows on the storm figures of the several charts, where the + concentrical circle afford us means for a just comparison of the + general course of wind which is approximately shown by the several + observations. + + "Perhaps we may estimate the average of the vorticose convergence, as + observed in the entire storm for three successive days, at from 5° to + 10°--out of the 90° which would be requisite for a congeries of + _centripetal_ or center-blowing winds. This rough estimate of the + degree of involution is founded only on a bird's-eye view of the + plotted observations. But, however estimated, this involution seems + to afford a measure of the air and vapor which finds its way to a + _higher elevation_ by means of the vortical movement in the body of + the storm." + +If the elevation of the air at the borders of the storm, and depression in +the middle, resulted from the outward tendency and "lateral movement" of +the revolving air, and from the _centrifugal force_, as in the experiment +with the water in a cylindrical vessel, as stated in the first paragraph +quoted, an _involution_ of from 5° to 10° from the action of a +_centripetal force_, must carry the air _inward_, and the _barometer +should stand highest in the middle of the storm_. The change is fatal to +his theory. The two are diametrically opposite in character and effect. In +one, the superior strata would be brought down in the center by the +_lateral pressure outward_; in the other, they would be elevated by the +_involution_, which "affords a measure of the air and vapor which finds +its way to a higher elevation," etc. It is perfectly obvious Mr. Redfield +has refuted his own hypothesis. + +In doing this, he is met by the other difficulty alluded to, which he does +not attempt to explain. This gathering of the air inward, spirally, by a +centripetal force, if it took place, not only would not depress, but _must +elevate the barometer in the center, above that of the adjoining +atmosphere_. + +When he first attributed the depression of the barometer to a lateral +movement and centrifugal force, he supposed the superior strata descended +into the depression, and their frigidity occasioned the condensation, and +cloud, and rain. How he now proposes to account for the formation of cloud +and rain during storms, while the warm air of the inferior stratum finds +its way to a higher elevation in the center of the storm, he does not +inform us, and we must wait his time. + + "I have," he says, "long held the proper inquiry to be, _what are + storms_? and not, _how are storms produced_? as has been well + expressed by another. It is only when the former of these inquiries + has been solved that we can enter advantageously upon the latter." + +The former does not seem to be yet solved, or the solution of the latter +commenced. Mr. Redfield tells us (page 259, and onward), that there is an +extended stratum of stratus-cloud, which overlies the storm, and that it +does not differ greatly from one mile in height. We are not told how the +air, which finds its way to a higher elevation during several days +continuance of such a storm, _gets through the stratum_. If he is right it +_must_ do so, and it would not answer to _suppose_ a very small opening or +gentle current through it, to carry off all the air which works inward in +a hurricane, during several days continuance. But he does not seem to +recognize either the necessity or existence of any _vent_ at all; nor is +there any; and this fact is open to the observation of every school-boy in +the country; and it is equally open to his observation that _when and +where the barometer is most depressed, the stratus storm-cloud is nearest +the earth_. Colonel Reid has much to say about the "_storm's eye_," or +"treacherous center" of a storm. A careful analysis of the instances where +the "storm's eye" is noticed will show that the term is applied, in the +northern hemisphere, to that lighting up in the W. or N. W., which is the +commencement of the clearing-off process, and attended with a shift of +wind to the fair-weather quarter: _i. e._, to W. or N. W. Just such an +"eye" as is seen when the last of the storm cloud has passed so far to the +east as to admit the rays of the sun under the western or north-western +edge of it. The same kind of "storm's eye" is described in the southern +hemisphere, except that the wind shifts to S. W. instead of N. W., that +being the clearing-off wind there. No instance of a "_storm's eye_" in +the center of the extended stratum of stratus-cloud, which overlies the +storm, can be found recorded, to my knowledge; and it is obvious that +Colonel Reid adopts the view of Mr. Redfield, that the westerly and N. W. +_fair weather_ winds are a part of the storm. So long as these gentlemen +hold to that opinion they will never solve the question, "_what are +storms?_" or reach the other, "_how are storms produced?_" + +Notwithstanding, Mr. Redfield asserts, or adopts the assertion, that the +inquiry should be, "What are storms?" not "How are storms produced?" that +inquiry should be a _rational_ one, and should not violate all analogy, or +call for an explanation which science can not _rationally_ furnish. Mr. +Redfield does not seem to have formed any just conception of the +_immeasurable power_ of a hurricane, _five hundred miles in diameter_; or +of the nature of that _rod_ which the _Almighty must insert in it, to +whirl it with such violent and long-continued force_; nor any just +conception of the tendency of the whirling mass, in the absence of his +"cylindrical vessel," to fly off, tangentially, into the surrounding air; +or of the nature or power of the centripetal force necessary to hold the +gyratory mass in its current, and gather it in involute spirals toward a +center. Nor has any other man who has witnessed, or read of +mountain-tossed waves; of the largest ships blown down and engulfed; of +towns submerged, and vessels carried far inland, and left in cultivated +fields, by the subsidence of the sea; of sturdy forests and strongly-built +edifices prostrated; or listened to the howling of the tempest, and felt +his own house rock beneath him, been able to conceive of any known form of +calorific or mechanical, or other power, acting from a comparatively small +center, which could hold such an immense irresistable mass of whirling air +in a circle, and _gather it_ in toward the center in gradually contracting +spirals. I confess that, to my mind, it seems little less than a mockery +of our intelligence for Mr. Redfield, or Professor Dove, or any other man, +how distinguished soever he may be, to tell us that all this is the result +of a "tendency to left-wise rotation" of ordinary winds, "coming into each +other," or "over-sliding," or "meeting," or "encountering," on this +"front," or that, down in Central America, or in the West Indies, or the +monsoon region; or to talk of "lateral overflows" from mere gravity; of +the ascent of warm air, or the descent of cold strata; of the _resistance +of adjacent passive air_, or other mere _atmospheric resistances_ in +connection with such _awful manifestations of power_. Their explanations +of these phenomena are not rational, nor can they be believed by any +rational man, who will bestow upon them half an hour of _comprehensive, +unbiased reflection_. + +Waiving many minor points of great force, for this notice of Mr. +Redfield's theory is already too much extended for my limits, I am +constrained to take issue with him on the fact, and to assert, +unhesitatingly, that in a _majority of instances no such barometric curve +exists_. + +Doubtless the depression beneath the storm is found, and exterior lateral +elevations may also be had by _extending the line into the usual fair +weather elevation on each side_, as Mr. Redfield is obliged to do, to get +his supposed circle of winds at all. Doubtless, too, the seamen sailing +out of a storm, on either _side_, and approaching fair weather, will have +a rising barometer. But from _front to rear, on the line of progression_, +in tropical storms, the curve does not exist on shore, in this latitude, +oftener than in two, or possibly three, cases in ten; and then only upon a +single state of facts--that is, when there is an interposition of N. W. +wind; and this, at some seasons, rarely occurs. An elevation usually +occurs before the storm, on its front, if it present an extensive easterly +front, as one of these classes does, and a _depression is left_ after it +has passed off, unless a considerable body of N. W. wind interposes, as +heretofore stated. But when there is not such interposition of N. W. wind +(for W., W. N. W., or even N. W. by W. will not suffice), there is not an +immediate rise of the barometer corresponding in rapidity and extent with +the fall, and frequently none during the first twenty-four hours of +bright, fair weather. Let the reader, if he has access to a barometer, +note this fact, for it is obvious and conclusive. + +Finally, there are other atmospheric conditions to which the barometric +changes are obviously due: + +1st. The counter-trade is of a different _volume_, at different times, +over the same locality, and hence a difference in the normal elevations of +the barometer. + +2d. It is at a different _elevation_, at different times, over the same +locality. It was so found by the investigations of the Kew Observatory +Committee referred to; has been so found by other aeronauts, and may +readily be seen by a careful, practiced observer. + +It is highest, with a high barometer, in serene weather, when a storm is +not at hand; and can sometimes be plainly seen to ascend when a +considerable volume of N. W. wind is blowing in beneath, and elevating, +simultaneously, the trade and the barometer. + +Opportunities occur every year, when the northern edge of the dissolving +stratus-cloud is attenuated, and the storm is clearing off in the N. W., +with wind from that quarter, and a rising barometer, when its gradual +elevation may be observed to correspond with the _volume_ of that wind. + +3d. During storms, with a low barometer, the _trade_ and the _clouds run +low_. This, too, is clearly observable, especially when the stratus-cloud +passes off abruptly, very soon after the rain ceases. In such cases the +barometer will remain depressed for a considerable time, unless another +storm supervenes speedily, or the wind sets in from the N. W. + +4th. The _trade, in a stormy state, moves faster_ than when in a normal +condition. This is observable during the partial breaks which frequently +occur in storms, and at other times. It is also inferable from the more +rapid progress of the more intense center, and other intense portions of +storms, and the consequent greater depression of the barometer, under such +centers or intense portions. (See the storm of Professor Loomis.) It is +obvious, also, from the greater rapidity of progress attending the more +intense and violent storms which all investigations discloses. + +These simple facts explain all the phenomena: + +1st. The trade stratum is a continuous unbroken sheet, and its descent +must displace a portion of the surface atmosphere. A portion of it is +impelled forward, aiding in the precedent elevation of the barometer, and +a portion is attracted backward, into the space from which a like portion +had been previously attracted by the passing storm cloud, forming the +easterly wind. + +2d. The increased progress of the stormy portion of the counter-trade +occasions an accumulation in front of the storm, and an elevation of the +barometer, and tends also to increase the _depression_ under the spot from +which it moves. The latter is, to some extent, counteracted by the thin +sheets of surface wind which are drawn in under the stratus from the +sides. That which is drawn from the front in successive portions, fills +the space from which like portions had been drawn to the westward, and +left behind in a passive state by the passing storm. Thus, the surface +atmosphere of New England may pass under the entire width of a storm, as a +gale; moving now in puffs with great violence, as it passes beneath +irregular and intense portions of the cloud, and now moderately; and be +left, in a passive state, in Kentucky, occupying the space from which the +atmosphere had been previously drawn by the same storm, _in like manner_, +on to northern Texas. + +3d. The nearer the stratus-cloud to the earth, the greater the +displacement of surface atmosphere, the lower the barometer, and, +ordinarily, the more violent the wind. First, because the same intensity, +which, by attraction, brings the trade near the earth, acts with greater +force upon the surface atmosphere; and, secondly, the storm winds, which +are often most rapid beneath the clouds and above the earth, are likely to +be felt with more violence at its surface, where the stratus cloud runs +low, especially at sea. + +I desire to commend all these facts, in relation to the theory of Mr. +Redfield, to the careful attention and observation of those who, although +believers in the theory, are not wedded to it; and who have a sincere +desire to understand the phenomena which are continually, and thus far, +_mysteriously_, occurring within two or three miles of us, while our +knowledge of the distant worlds around us--the science of astronomy--seems +almost perfect. + +I will return to a further and a careful consideration of the nature of +the reciprocal action between the earth and the counter-trade, and the +facts bearing upon the question, in another chapter. It is obvious that +received theories can not aid us materially in the inquiry. + + + + +CHAPTER X. + + +We are yet ignorant of the true nature of magnetism. We trace its lines, +as in the diagrams, upon and around the magnet; but we can only do this +with soft iron, or other substance, in which magnetic action may be +induced. We know that these lines are currents, or lines of force, for +that force produces sensible effects, and we measure it by the movements +of the needle. We know that these lines may be _deflected_ by other +magnetic bodies, and concentrated upon them. We know that the earth, and +the smallest magnets, exhibit properties in common. The poles of the +magnet are some distance from its extreme ends--so are those of the earth. +The intensity increases, from the center, or near it, to the poles of the +magnet, as shown by its attraction; and the same increase of magnetic +intensity, from the magnetic equator to the magnetic poles, or near them, +is traced upon the earth. + +We know that there are two lines, or rather _areas_, of greater intensity +upon the globe. One extending from the American magnetic pole, +south-eastwardly, to a corresponding pole in the southern hemisphere; and +another, the Asiatic, extending from the Siberian pole to a corresponding +southern one, in like manner. We know that, from those lines or areas, +the intensity, east and west, on the same parallel of latitude, decreases +each way, to about midway between them. Thus, calling the intensity where +Humboldt found the magnetic equator over South America, in 7° 1' south +latitude, 1, or unity--the least intensity known is, .706, found at the +magnetic equator, over the South Atlantic, and at its most southern +depression; and it increases to 1.4 in the West Indies, and to 2.0099 upon +one or more points of the North American continent, south of the magnetic +pole, and about the meridian of 92°. That it is 1.805, at Warren, Ohio, in +latitude 41° 16', and longitude 72° 57', and decreases to 1.774 at New +Haven, Connecticut, in latitude 41° 18'. That it is but 1.348 at Paris, +nearly one third less than on the same latitude in some portions of this +continent. That the line of equal intensity, or "_iso-dynamic_" line, of +1-8/10, is a closed curve of an oval shape, extending somewhat below 40°, +in the longitude of Cincinnati, and reaches off nearly to Bhering's +Straits, on the west; rising in a similar manner, though not so abruptly, +on the east; including the great northern lakes and a considerable part of +Hudson's Bay. While the iso-dynamic lines of 1-85/100, and 1-875/1000, are +smaller ovals, included within the former. Such, at least, is the present +belief from such investigations as have been made. (See an article by +Professor Loomis, American Journal of Science, new series, vol. iv. p. +192.) + +Our subject demands a still closer examination of the elements of +magnetism and its associated electricities, and their influence upon +climate and the atmosphere with a view to the solution of the questions in +hand, and we will pursue the inquiry in the present chapter. + +Waiving, for the present, any further notice of the fact that the +counter-trades are concentrated over, and contiguous to, this area of +intensity, for the purpose of examining the magnetic phenomena +independently, and intending to return to a consideration of their +connection with it, we observe:--That it is now well settled that the +iso-geothermal lines, or lines of equal terrestrial heat, are coincident, +or nearly so, with the lines of equal magnetic intensity. The points where +the magnetic intensity is at a minimum, on the magnetic meridian, are the +warmest points of that meridian, and those where it is most intense, the +coldest. + +The magnetic elements of a place may be computed from its thermal ones. +The laws producing or governing the distribution of one, have an intimate +physical relation with those producing or governing the other. Professor +Norton ably sums up a discussion of the subject (in the American Journal +of Science for September, 1847), omitting the theoretic propositions, as +follows: + + "1. All the magnetic elements of any place on the earth may be + deduced from the thermal elements of the same; and all the great + features of the distribution of the earth's magnetism may be + theoretically derived from certain prominent features in the + distribution of its heat. + + "2. Of the magnetic elements, the horizontal intensity is nearly + proportional to the mean temperature, as measured by Fahrenheit's + thermometer; the vertical intensity is nearly proportional to the + difference between the mean temperatures, at two points situated at + equal distances north and south of the place, in a direction + perpendicular to the iso-geothermal line; and, in general, the + direction of the needle is nearly at right angles to the + iso-geothermal line, while the precise course of the inflected line + to which it is perpendicular may be deduced from Brewster's formula + for the temperature, by differentiating and putting the differential + equal to zero. + + "3. As a consequence, the laws of the terrestrial distribution of the + physical principles of magnetism and heat must be the same, or nearly + the same; and these principles themselves must have, toward one + another, the most intimate physical relations." + +The magnetic elements, of which Professor Norton speaks, are the +declination, dip, and horizontal and vertical forces or intensities. + +I have said, that toward the areas of greatest magnetic intensity, the +needle every where declines. So as intensity increases, from the magnetic +equator toward the poles, the needle, when so suspended as to permit of +the motion, _dips_, inclines downward, and the dip is greatest, on the +same parallel, where intensity is greatest. To my mind, the magnetic +elements are very intelligible. They are all attributable to attraction, +and attraction is greatest where intensity is greatest. There is nothing +in the earth or atmosphere to make the needle point northerly rather than +in any other direction, except magnetic intensity. Thus, the greater +intensity of magnetism near the northern and southern points of the globe, +attracts the corresponding ends of the needle in those directions. And, as +magnetism increases in quantity or intensity, and the poles are +approached, the attraction increases, and the needle dips more and more, +till the focus of intensity and attraction is reached, and then it becomes +perpendicular. So magnetism is unequally diffused, meridionally, in or +over the earth, and there are two equidistant areas where its quantity or +intensity is greatest. These exert a lateral attraction upon the needle; +it yields to this attraction, and hence its declination. If it is carried +on to one area of intensity, and to the center of it, it will point to the +northern focus of intensity or magnetic pole; and, if carried a trifle +further west, it will yield to an eastern attraction, and point directly +north. If carried still further west, its declination _east_ will +increase. Thus its normal direction is to the pole, on the central focus +of intensity, and when it points directly north it is west of the central +line of intensity. And thus, it seems to me, all the magnetic elements may +be resolved into the one element of attraction by excess of intensity or +activity. + +This impression is strengthened by the fact that the needle moves to the +east in the morning, when the solar rays increase magnetic activity in +that direction, and west again, as their influence increases there. + +Now, these elements--the declination and horizontal and vertical +forces--all these periodical, regular, and irregular variations of +magnetic activity, are intimately connected with the variations of +atmospheric condition: + +First, They show an increase of activity during certain hours of the day, +corresponding to, and obviously connected with, the diurnal atmospheric +changes. + +Second, They show an increase of activity during the northern transit of +the atmospheric machinery--an _annual_ variation. + +Third, They show an increase in that activity during the latter portion of +each decennial period, conforming to the occurrence of solar spots. + +And, fourth, _Irregular variations_ of activity, corresponding with the +_irregular changes_ of atmospheric condition. + +We will examine these results, and in doing so, take those of the element +of declination--one answering for all. + +The magnetic needle moves to the west in summer, from about 8 A.M. till +about 2 P.M., and the extent of its progress, during that period, +constitutes the magnitude of its daily variation. It is found that this +variation differs in different months, and that it is normally greatest in +the summer months, and least in the winter, in the ratio of about two to +one. It is further found, that in different years the maximum activity +occurs in different months, and that the years differ also, and there is a +distinctly marked decennial period, corresponding most remarkably with the +decennial maxima of recurring solar spots, as observed by Schwabe. Dr. +Lamont, of Munich, gives us the following table of magnitude of +declination there, for the ten years preceding 1851, which clearly +exhibits this fact, and also the greater intensity during the northern +transit of the atmospheric machinery. He says: + + "The magnitude of the variations of declination have a period of ten + years. For five years there is a uniform increase, and during the + following five years a uniform decrease in the variations. With us + the magnetic declination is a minimum at about eight o'clock in the + morning, and is greatest at two o'clock in the afternoon. Subtracting + the declination at eight o'clock from that at two o'clock, we obtain + _the magnitude of the diurnal motion_. From the hourly observations, + conducted in this observatory since the month of August, 1840, we + ascertain the following to be the magnitude of the diurnal motion for + each month separately." + + +-------------------------------------------------------------------+ + | | Jan. | Feb. | March.| April.| May. | June. | July. | Aug. | + +-------------------------------------------------------------------| + | 1841 | 3.72 | 5.13 | 8.43 | 11.49 | 11.47 | 11.49 | 10.07 | 9.86| + | 1842 | 3.65 | 4.74 | 8.34 | 10.33 | 9.31 | 9.78 | 8.38 | 9.03| + | 1843 | 3.82 | 4.08 | 6.87 | 9.71 | 9.24 | 10.14 | 9.57 | 10.08| + | 1844 | 2.81 | 3.43 | 6.95 | 9.53 | 8.42 | 8.88 | 8.38 | 9.28| + | 1845 | 2.20 | 4.69 | 8.26 | 11.93 | 10.88 | 10.73 | 9.44 | 10.42| + | 1846 | 3.30 | 6.94 | 9.53 | 12.27 | 12.58 | 11.21 | 11.37 | 11.49| + | 1847 | 3.30 | 6.35 | 9.85 | 12.43 | 11.81 | 11.76 | 10.94 | 12.87| + | 1848 | 6.52 | 9.01 | 11.96 | 14.56 | 14.22 | 13.80 | 14.67 | 15.40| + | 1849 | 7.27 | 8.42 | 14.08 | 16.86 | 13.67 | 13.86 | 12.57 | 11.54| + | 1850 | 5.98 | 8.84 | 12.15 | 14.32 | 14.05 | 13.39 | 12.53 | 12.68| + +-------------------------------------------------------------------+ + +----------------------------------------------------+ + | Sept. | Oct. | Nov. | Dec. | Autmn | Spring| Year.| + | | | | |& Wint.| & Sum.| | + |----------------------------------------------------| + | 8.78 | 6.82 | 3.71 | 2.89 | 5.12 | 10.53 | 7.82| + | 7.72 | 7.05 | 3.86 | 2.81 | 5.07 | 9.09 | 7.03| + | 8.81 | 6.82 | 3.82 | 2.79 | 4.70 | 9.59 | 7.15| + | 8.23 | 6.54 | 3.94 | 2.98 | 4.44 | 8.79 | 6.61| + | 8.82 | 7.34 | 4.49 | 8.34 | 5.89 | 10.87 | 8.13| + | 10.39 | 7.82 | 5.66 | 3.22 | 6.08 | 11.25 | 8.81| + | 12.06 | 11.53 | 7.06 | 4.70 | 7.63 | 11.98 | 9.55| + | 14.00 | 10.30 | 5.78 | 3.53 | 7.85 | 14.44 | 11.05| + | 10.79 | 9.12 | 5.41 | 4.09 | 8.06 | 13.21 | 10.64| + | 12.64 | 9.04 | 6.20 | 3.45 | 7.61 | 13.27 | 10.44| + +----------------------------------------------------+ + +The Philadelphia and Toronto observations disclose the same state of +facts. + +Dr. Lamont, also, in his article, gives us the following table of the +magnitude of the variations derived from observations at Gottingen: + + +--------------------+ + | Year.|Mean of Year.| + |--------------------| + | 1835 | 9.57 | + | 1836 | 12.34 | + | 1837 | 12.27 | + | 1838 | 12.79 | + | 1839 | 11.03 | + | 1840 | 9.91 | + | 1841 | 8.70 | + +--------------------+ + +A comparison of these tables, and particularly the latter, with Schwabe's +table of spots, is interesting. There is obviously a greater mean +variation when the spots are most numerous. Comparing the two with the +tables of Hildreth, in relation to the temperature, from 1830 to 1840, +there is, to say the least, a most remarkable coincidence. And there are +others equally remarkable. + +There are also irregularities of action disclosed by all, in different +months of the different years, and of the same year, which are obviously +connected with the difference of the seasons; and there are constantly +occurring irregularities and disturbances which correspond with the, as +constantly occurring, irregular atmospheric phenomena. A wide field is +here opened for investigation and research. I have not time or opportunity +to pursue it. Enough appears, so far as I have examined, to confirm the +belief that magnetism is actively concerned in the production of the +varied changes, as well as the normal conditions of the weather. + +In what manner does it act? An answer to this requires an extension of the +inquiry. The lines of magnetic force are every instant passing upward from +the earth, _around_ and _through_ us. Their connection with heat is +unquestionable. They are intimately associated, also, with another equally +obvious and intensely active agent--electricity. We speak of this as an +independent, imponderable, elementary body, but how little we yet know of +it. It is every where, in every thing, easily excited into action, and +then traceable to a certain, but limited extent. It is set in motion, and +becomes obvious to us, by the chemical action of the acids and metals of +a galvanic apparatus. We separate it from the atmosphere by friction and +excitation, upon non-conductors, as in the electric machine; by the +cleavage of crystals and other exciting operations. We obtain it from +magnets, by the magneto-electric machine, and from the lines of magnetic +force which are ever passing into the atmosphere from the earth, by +intersecting them with a movable iron wire, properly insulated. _From the +current of magnetism which has passed through us from the earth, +electricity may thus be separated and collected over our heads._ We set it +in motion, and obtain it _by heating_ different metals in connection, or +the same metal unequally; and from certain animals--like the torpedo and +the gymnotus--whose organization is such as to enable them to evolve it. +In all these cases, and they constitute an epitome of the principal +methods by which we obtain it in a distinct form, it is made to flow in +currents. When thus obtained, and imprisoned in non-conductors, it may be +discharged, and with somewhat different effect, as it is discharged in a +mass, disruptively, as it is called, as from the clouds in lightning, or +permitted to flow convectively, in currents, along the wires of a galvanic +apparatus, or in heated air, as from the earth to a cloud in the tornado. + +It is, moreover, capable of division into positive and negative, and when +concentrated or disturbed in one body, it tends to create a similar +disturbance or division in a contiguous mass. To this action of +electricity, the term static induction is applied. Thus, a positively +electrified body _induces_ a division of the electricity in a contiguous +body, if both are insulated or surrounded by a non-conducting medium; the +negative electricity of the contiguous body being attracted by, and +tending to pass to, the positive of the adjoining body, and the positive +being repelled to the opposite side. That, in its turn, if sufficiently +powerful, tends to disturb the electricity of its neighbor, and attract +away its negative electricity; or, if the body which contains it is free +to move, to attract that. Thus, by the conflicting action of a positive +atmosphere, and a negative earth, and perhaps counter-trade, influenced by +magnetism and the solar rays, the currents and winds of the atmosphere are +produced, the atmosphere moving with exceeding ease and rapidity. +Electricity, excited into currents, or obtained and discharged in either +of the methods enumerated, is identical in character, and produces certain +well-known effects: + +1st. Physiological.--Shocking and convulsing the animal system; producing +a peculiar sensation on the tongue, and a flash before the eyes, and in +sufficient quantity destroying life. + +2d. Magnetic.--_Deflecting the needle_, and, by a suitable arrangement of +wire into helices, _conferring magnetic power_, or constituting magnets. + +3d. Luminous.--Producing light--by a spark, as it does in natural +phenomena--by the glow, the brush discharge, the ball of flame, the flash, +or the chain of lightning, and probably the aurora. + +4th. Evolving heat.--Melting metallic substances by concentration, with a +great intensity of heat--as the wire of the galvanic apparatus, and as is +sometimes seen in the effects of lightning in fusing metals on persons +stricken; and setting combustibles on fire. + +5th. Attraction and repulsion.--Attraction, when the currents flow +parallel with each other, or are of opposite natures, and repelling when +of like character. + +6th. Induction.--Inducing attendant circular or other secondary currents, +such as may be seen in the atmosphere during its most violent displays of +active energy. + +7th. Capable of being dissipated by heated air, or carried off by +moisture, although isolated by dry air, of ordinary temperature, which is +a bad conductor. + +Now, although magnetism can not be collected, imprisoned, or discharged, +like electricity, or collected at all, but by its adherence to some +substance capable of magnetization, it is obvious there is an intimate +association, at least, between it and electricity. _They are never found +alone._ All _electricity_ will _magnetize_. All _magnetism_ will evolve +electricity. All _currents_ of _electricity_ have _encircling currents_ of +_magnetism_, and all deflect the magnetic needle. All magnetic currents +give out to intersecting wires, _currents of electricity_, and all magnets +_induce_ them. + +Electricity, therefore, whether identical in substance with magnetism, but +differing in form, or whether merely associated with it, as is variously +believed, should be present with magnetism in greater quantity or +intensity where magnetism is most intense, and active, and whenever +present, should be active and influential. And so we find, from +observation, the fact to be. No inconsiderable effort has been made by the +advocates of the caloric and mechanical theories, to ignore the agency of +electricity and of magnetism, in the production of the varied +meteorological phenomena. But it will not do. The phenomena, grouped and +analyzed, disclose a potential-controlling, magneto-electric agency, and +meteorology will advance rapidly to perfection, as a simple, intelligible, +and practical science, _as soon as that agency is admitted_. + +Electricity is always perceptibly present in storms and showers within the +tropics. Most of the rain, from the tropical belt, falls from "thunder +showers." So hurricanes and typhoons, and all tropical storms, are +confessedly, and in proportion to their intensity, "_highly electric_." +This excess of quantity or activity of electricity, exists in connection +with the movable atmospheric machinery. When it moves up north in summer, +and arrives at its highest point of northern transit, _storms_ are very +_uncommon_, and the tropical forms of cloud and showers, with thunder and +lightning, prevail. This is most obvious, if not most influential, where +the magnetic intensity is greatest. Violent showers, and gusts, and +tornadoes, are more frequent in this country than in Europe; and over the +area of greatest intensity, as in Ohio, than at a distance on the extreme +eastern or western coast. And the same is true over the intense magnetic +area of Asia. + +Electricity, too, like magnetism, has its diurnal, and doubtless its +annual and decennial variations, and also its irregular ones, and they are +most obviously and intimately connected. Magnetism and electricity +together, constitute the aurora. Its culmination is in the magnetic +meridian--it affects the telegraph wires--is connected with the irregular +disturbances which affect the magnetic needle, and does not exist in the +limits of the trades, although occasionally seen from thence, when it +passes south, and near them. + +The aurora sometimes extends south in waves, as do the magneto-electric, +atmospheric, periodical changes of cold and heat, and storm, and sunshine. +_The aurora is connected with the formation of cloud_, and with a smoky +atmosphere, similar to that with which we are familiar in summer and +autumn. Thus Humboldt (Cosmos, vol. i. pp. 191, 192). + +"This connection of the polar light with the most delicate cirrus clouds, +deserves special attention, because it shows that the electro-magnetic +evolution of light is a part of a meteorological process. Terrestrial +magnetism here manifests its influence on the atmosphere, and on the +condensation of aqueous vapor. The fleecy clouds seen in Iceland, by +Thienemann, and which he considered to be the northern light, have been +seen in recent times by Franklin and Richardson, near the American north +pole, and by Admiral Wrangel on the Siberian coast of the Polar Sea. All +remarked 'that the aurora flashed forth in the most vivid beams when +masses of cirrus-strata were hovering in the upper regions of the air, and +when these were so thin that their presence could only be recognized by +the formation of a halo round the moon.' These clouds sometimes range +themselves, even by day, in a similar manner to the beams of the aurora, +and then disturb the course of the magnetic needle in the same manner as +the latter. On the morning after every distinct nocturnal aurora, the same +superimposed strata of clouds have still been observed that had previously +been luminous. The apparently converging polar zones (streaks of clouds in +the direction of the magnetic meridian), which constantly occupied my +attention during my journeys on the elevated plateaux of Mexico, and in +northern Asia, belong, probably, to the same group of diurnal phenomena." + +Mr. William Stevenson gives us (in the London, Edinburgh, and Dublin +Philosophical Magazine for July, 1853) an interesting article on the +connection between aurora and clouds. His observations on this most +important branch of the subject trace a connection between the aurora and +the formation of cloud, and open up, as he says, "a most interesting field +for observation which promises to lead to very important results." Such +observations point with great significance, to the primary influence of +the magneto-electricity of the earth. + +To the difference in the magnetic intensity of the eastern portion of this +continent, compared with Europe and our western coast, very much of the +difference of climate, so far as temperature is involved, may be +attributed. We have seen in what manner the iso-thermal lines surround +these areas of intensity. So the most excessive climate--that is, the +climate where the greatest extremes alternate, other things being equal, +is upon or near the line or area of greatest magnetic intensity. I say +other things being equal, because large bodies of water modify climates by +equalizing the seasons--making the summers cooler and the winters warmer +than the mean of the parallel. + +Thus, our great interior lakes modify the climate in relation to +temperature in their vicinity. Their summers are cooler and their winters +warmer; but westward of them the same line of equal summer temperature, or +iso-thermal line, rises with considerable abruptness, and the winter, or +iso-cheimal line of equal temperature, falls in a similar manner. Thus, +the range of the thermometer, from the highest elevation to the lowest +depression, for the year, is very great, while in the tropics the range is +comparatively small. From observations made at the military posts of the +United States, Dr. Forrey deduced summer and winter lines of equal +temperature, starting from the vicinity of Boston and running west, which +showed most remarkably the rise of the summer lines as intensity +increased, and the fall of the winter lines in like manner. + +The influence of the lakes was also most obvious. The elevation of the +earth increases, going west, to about 700 feet at the surface of the +lakes, and to nearly 4,000 feet at the eastern base of the Rocky +Mountains; and, although temperature does not decrease to as great a +degree when the elevation above the level of the sea is _gradual_, yet +some allowance should doubtless be made for that elevation on this line. +When that allowance is made, the ascent of the summer line, to the north, +over the area of greatest intensity, is strikingly apparent. + +Dr. Forrey also instituted a comparison between Fort Snelling, where the +climate is as excessive, and the range of the thermometer as great, as in +any portion of the continent in the same latitude, with Key West, and I +copy his diagram. It is very instructive, showing the gradual mean rise of +the temperature, from January to December, inclusive, while the cross +lines show the _extremes of each month_. + +Perhaps the most interesting part of it, is the illustration of the +monthly extremes, and the contrast between them, in the excessive climate +of Fort Snelling, and the tropical one of Key West. Each is a type of the +climate in which it is situated. The annual range and monthly extremes are +small in tropical countries, and large in extra-tropical ones. The extreme +range, or greatest elevation of heat, contrary to what is generally +supposed, is greater at Fort Snelling than at Key West. But the climate of +the latter is modified by the adjoining ocean. + +I copy, also, a table (p. 304), showing the range of the thermometer for +the year, and the maxima and minima, during each month, at several other +places in this country, and at London and Rome, for the purpose of showing +the extent of the ranges compared with those places; and also, that these +great changes in each month occur very uniformly all over the country, +and may always be expected, and with considerable regularity. They are +incident to our climate. I wish I could engrave the foregoing diagram, and +the following table, upon the mind of every man, woman, and child in the +country; and under it, in ever-visible letters, these words of precaution: +CONFORM TO THE PECULIARITIES OF YOUR CLIMATE, AND CLOTHE YOURSELVES, AT +ALL TIMES, IN ACCORDANCE WITH THE ALTERNATIONS OF THE WEATHER. If heeded, +they would save thousands, every year, from premature death. + + +[Illustration: Fig. 18.] + + +The effect of this difference of magnetic intensity upon the climate of +Europe is marked. There, the excessive summer heat, which our greater +magnetic intensity and larger volume of counter trade give us, is unknown. +Hence, while we can grow Indian corn (which requires the excessive summer +heat) over all the Eastern States, up to 45°, and in some localities east +of the lakes to 47° 30', and to 50° west of them, to the base of the Rocky +Mountains, and notwithstanding the increase of elevation, they can not +grow it except over a limited area, and with limited success. Nor can +they, or the inhabitants of any other country except China, grow +profitably the kind of cotton which is so successfully grown in the +Southern States of the Union. Nor can China do so to a considerable +extent, because of the mountainous character of the surface. To a level +and remarkably watered country, greater magnetic and electric intensity, +and a greater volume of counter-trade, we are, and ever shall remain, +indebted, for an almost exclusive monopoly in the growth of two of the +most important staple productions of the earth. On the other hand, +although the same magnetic intensity, and its winter excess of positive +electricity and cold, make our winters extreme, there are but few of the +productions of temperate latitudes which we can not grow successfully, and +they are comparatively unimportant. + + A Fort Vancouver, Oregon Territory + B Fort Brady, outlet of Lake Sup. + C Hancock Barracks, Houlton, Me. + D Fort Armstrong, Rock Island, Ill. + E West Point, New York + F Washington, D. C. + G Jefferson Barracks, near St. Louis + H Fort King, interior of East Florid. + I Environs of London + K Rome, Italy + + A B C D E F H I J K + + Lat. 45° 46° 46° 41° 41° 38° 38° 29° 51° 41° + 37' 39' 10' 28' 22' 53' 28' 12' 31' 54' + Annual + Range. 78 110 118 106 91 84 89 78 67 62 + + Jan. Min. 17 -21 -24 -10 -1 14 10 33 16 29 + Max. 58 40 41 48 53 57 60 83 49 58 + Feb. Min. 32 -22 -11 -6 2 16 11 43 19 33 + Max. 55 44 42 56 56 62 70 84 54 60 + Mar. Min. 32 -7 -1 13 16 28 31 39 24 37 + Max. 60 51 54 70 72 70 76 87 60 65 + Apr. Min. 32 18 24 33 40 36 38 54 26 44 + Max. 70 62 74 78 62 73 83 93 69 74 + May. Min. 32 32 81 44 47 50 45 64 33 52 + Max. 75 79 83 84 72 85 88 97 78 80 + June. Min. 45 41 38 57 57 59 59 73 39 60 + Max. 95 86 90 89 79 92 95 105 80 88 + July. Min. 40 39 45 62 64 64 50 73 41 64 + Max. 95 84 90 95 86 94 96 102 83 91 + Aug. Min. 44 49 46 60 62 63 66 72 42 62 + Max. 95 84 85 91 87 93 96 104 79 91 + Sept. Min. 43 40 33 51 56 51 51 70 34 55 + Max. 88 75 78 87 83 88 88 99 75 85 + Oct. Min. 50 27 24 82 42 33 38 41 30 46 + Max. 66 70 72 73 69 77 80 91 68 77 + Nov. Min. 32 15 4 26 36 28 27 30 22 39 + Max. 58 58 60 64 63 66 69 82 56 67 + Dec. Min. 32 -7 -4 15 20 17 14 36 20 31 + Max. 55 42 53 62 56 61 64 79 53 60 + +This excess of magnetic intensity and electricity not only gives a +peculiar character to our vegetation, but also to our race, our animals, +and every thing. He who supposes that the restless activity and energy of +the people of the United States is the result of habit, or education, or +any fortuitous circumstances alone, is mistaken. Let him watch the +contrast in his own feelings during those occasional languid, damp, and +sultry, although not thermometrically, hot days--which so much resemble +the summer weather of England--with those days of bright, bracing, N. W. +and S. W. air, so much more frequent here, and he will appreciate the +difference. That term "bracing," so much in use, will express the effect +of this peculiar weather. It "girds up the loins," both of body and mind. +Men and animals can work with more ease, even in our peculiar extremes of +heat, than they can in England, and fatten with less. + +A similar difference in degree is found between our climate and that of +the Pacific portion of our country. Something is due to the difference in +the volume and moisture of the counter-trades, and something to the +contiguity of the Pacific Ocean; but to the difference in +magneto-electric intensity, the contrast is mainly due. Corn and cotton +will be grown, to some extent, in the valleys west of the meridian of +105°, but never as successfully as east of it. + +The aurora is periodical, like all the other atmospheric phenomena, but +its periodicity is not accurately ascertained. It is believed to have +occurred much oftener during the second quarter of this century, than +during the first. It is known, however, to occur most frequently in the +spring and fall; and during those periods when the active and rapid +transit of the atmospheric machinery produces the greatest degree of +magnetic disturbance. This identifies it with terrestrial magnetism. +Dalton gives us the following table of observations, arranged according to +the months when they were seen. + + Jan. Feb. Mar. Apr. May. June. July. Aug. Sept. Oct. Nov. Dec. + + (1) 18 18 26 32 21 5 2 21 23 36 38 9 + (2) 21 18 23 13 3 2 1 3 35 22 22 21 + (3) 21 27 22 12 1 5 7 9 34 50 26 15 + (4) 5 6 4 8 10 7 6 14 14 17 5 6 + +(1) contains those observed by him at Kendall; (2) are taken from another +list; (3) is MARIAN'S list of those observed before 1732; and (4), those +seen in the State of New York in 1828 and 1830. + +Mr. Stevenson's table of those observed by him at Dunse, from 1838 to +1847, inclusive, is as follows: + + Jan. Feb. Mar. Apr. May. June. July. Aug. Sept. Oct. Nov. Dec. + 32 20 18 18 3 0 2 14 43 34 30 23 + +Observations in this country correspond substantially with the foregoing. +They are, however, seen here in the summer months more frequently than in +Europe. See an article by Mr. Herrick (American Journal of Science, vol. +33. p. 297). In this, also, they conform to our greater magnetic intensity +and more excessive climate. + +The auroras appear to follow the polar belts of condensation and +precipitation. Dalton considers them indications of fair weather. They are +often most brilliant just after a storm has passed, but their continuance +is no indication that another will not follow within the usual period. + +The condensation with which the aurora is connected, is not, in my +judgment, often in the counter-trade, or below it, but above, where feeble +condensation has been seen by aeronauts when invisible at the surface of +the earth. Neither the height of this condensation, not that of the +aurora, have been satisfactorily ascertained. The aurora of April 7th, +1847, was a favorable one for observation. It was carefully and +attentively watched by Professor Olmsted, Mr. Herrick, Dr. Ellsworth, and +others, and they are intelligent and skillful observers.[9] But the nature +of the aurora forbids reliance on parallax, or measurements founded on the +time when, any portion of the bow or arch rises in range of a particular +star. The bow or arch moves southwardly, but the same rays or currents do +not. The wave of magnetic _activity_ moves south, and each successive +current, as it is reached by the _impulse_, becomes luminous. Hence the +observers, when distant, do not see, at the same time, or at different +times, the same rays. The phenomenon is unquestionably magneto-electric. +Electricity becomes luminous in a vacuum, and De la Rive, by combining the +electric currents with those of magnetism, produced all the peculiarities +of the aurora. The magnetic currents, passing from the earth, have +associated electric ones in connection, and these, in the upper attenuated +atmosphere, become luminous. Whether, as De La Rive supposes, by combining +with the positive electricity existing there, or because the associated +electric currents are _then_ in excess, not being intercepted by +atmospheric vapor and returned to the earth in rain, we can not know, nor +is it very important we should. + +Having thus taken a general view of the nature of magnetism and its +associated electricities, and their connection with the general and +obvious peculiarities of climate, let us approach more nearly the varied +atmospheric phenomena, resulting from variations of pressure, temperature, +condensation, and wind, and give them a closer consideration. They all +have regularity and periodicity--they all occur in degree, and in +connection with magnetism and electricity, during the twenty-four hours of +every serene and normal summer's day. Grouped together, in comparison with +the changes in the activity and force of the magnetic elements, their +connection is clearly discernible. + +The day may be said, with truth, to commence, in some portion of the +summer, at 4 A.M. The atmospheric does at all seasons. At that hour the +barometer is at its morning minimum. It has, as we have said, a +perceptible diurnal variation of two maxima and two minima. Its periods of +depression are at 4 A.M., and 4 P.M., and of elevation at 10 A.M., and 10 +P.M. The difference between the elevation and depression is considerable +within the tropics, where Humboldt tells us the hour of the day can be +known by the height of the barometer, and it decreases toward the poles. +At 4 A.M. it is then at one of its minima, and rises till 10 o'clock. + +At, or about the same period, and sometimes when the barometer is falling, +and previous thereto, there is a tendency to fog in localities subject to +that condensation. This tendency is sometimes observed at the other +barometric minimum, late in the afternoon or early in the evening, but +less frequently. The tendency to fog condensation is greatest in this +country about the morning minimum. It seems to be owing to the influence +of the earth; it is confined to the surface atmosphere, and is apparently +produced by the inductive agency of the negative electricity of the earth. +It disappears, whether it be high or low fog, about the time when the +barometer attains its morning maximum, or about 10 A.M. + +At about that period, when there has been fog, or earlier, when there has +not, and sometimes as early as 8 A.M., there is a tendency to trade +condensation--cirrus in mid-winter, and a cumulus in mid-summer, and, +during the intermediate time, a tendency to cirro-stratus, partaking more +or less of the character of one or the other, according to the season. + +Temperature, in summer, commences its diurnal elevation about 4 A.M., +also, and rises till about 2 P.M. From that time it falls with very little +variation till 4 o'clock the next morning. It has but one maximum and one +minimum in the twenty-four hours. + +As the morning barometric maximum approaches, and the heat increases the +magnetic activity, condensation in the trade appears, or induced +condensation in the upper portion of the surface atmosphere, that portion +near the earth is affected and attracted--and the "wind rises," according +to the locality, the season, and the activity of the condensation. The +tendency to blow increases with the tendency to trade and cumulus +condensation, and continues till toward night, when it gradually dies +away, unless there be a storm approaching. As the heat increases, and +stimulates magnetism into activity, the magnetic needle commences moving +to the west, its regular diurnal variation, and continues to do so until +about 2 P.M., when it commences returning to the east, and so continues to +return until 10 P.M., when it moves west again until 2 A.M., and from +thence to the east, till 8 A.M. + +Similar variations also take place in the horizontal force, as evinced by +the action of the magnetometer needle, and in the vertical force, as shown +by the oscillations. So that it is evident that there are two maxima, and +two minima of magnetic activity every day, shown by all the methods by +which we measure magnetic action and force--more than double at the acme +of northern summer transit over that of winter, and proceeding _pari +passu_, with the other daily phenomena--evincing the same irregular action +which the other phenomena evince. Still another phenomenon, which has a +daily change, is electric tension, or the increase or decrease in the +tension of the positive or true atmospheric electricity. + + +[Illustration: Fig. 19.] + + +The following table shows the mean two hourly tensions for three years, at +Kew, viz.: + + Hours 12 P.M. 2 A.M. 4 A.M. 6 A.M. 8 A.M. 10 A.M. + Number of observations 655 784 804 566 1,047 1,013 + Tension 22.6 20.1 20.5 34.2 68.2 88.1 + + Hours 12 A.M. 2 P.M. 4 P.M. 6 P.M. 8 P.M. 10 P.M. + Number of observations 848 858 878 874 878 1,007 + Tension 75.4 71.5 69.1 84.8 102.4 104 + +From this it will be seen that the tension of electricity is at a minimum +at 4 A.M., also, that it rises till 10, falls till 4 P.M., but not as +rapidly, rises till 10, falls again till 4 A.M., or the close of the +meteorological day--having two maxima and minima, as have most of the +phenomena thus far considered. + +In order to see what the connections between these ever-present, daily +phenomena are, and their connection with other phenomena, and that we may +understand their normal conditions, I will trace them approximately in a +diagram (figure 17.) + +The foregoing diagram of the daily phenomena of a summer's day, when no +disturbing causes are in operation, no storm existing within influential +distance, and no unusual intensity or irregular action of any of the +forces present, affords a basis for considering the various phenomena of +the weather in all its changes and conditions. + +It is obvious that the other phenomena do not all depend upon temperature +merely, if indeed any of them do. + +Temperature has but one maximum and minimum, and that is exceedingly +regular, and does not correspond with any other. + +The barometer has two; electric tension, two; magnetic activity, two; +condensation, two--one the formation of cloud, and the other the formation +of fog and dew; wind, one--resembling temperature in that respect, but +embracing a much less period. + +Fog forms at one barometric minimum, and cloud at another. + +Fog forms at one period of the magnetic variation, cloud at another. + +The formation of cloud corresponds with the greatest intensity of magnetic +action, and its associate electricities. But the oscillations of the +barometer do not correspond with either. And thus, then, we connect them: + + CAUSE. | EFFECT. | EFFECT. + | | + Increase of magnetic|Decrease of pressure. |Increase of primary + or magneto-electric | |condensation. + activity, as shown |Of positive electric | + by declination and |tension. |Of wind. + increase of | | + horizontal and |Of surface condensation,|Of electrical disturbance + vertical force. |_i. e._, fog and dew. |and phenomena in the + | |trade and its vicinity. + +This connection is equally obvious if the order is reversed--thus; + + CAUSE. | EFFECT. | EFFECT. + | | + Decrease of magnetic|Increase of pressure. |Disappearance of primary + or magneto-electric | |condensation. + activity. |Of tension of | + |atmospheric electricity.|Of wind, and + | | + |Of surface condensation,|Of electric disturbance + |_i. e._, fog and dew. |in the trade and its + | |vicinity. + +If we examine still more particularly the different phenomena, we shall +find the same relative action of the forces carried into all the +atmospheric conditions, however violent. + +1. The barometer falls when horizontal magnetic force, and a tendency to +cloud and wind, increase; and rises when they decrease. This corresponds +with the character of the irregular barometric oscillation. Barometric +depressions accompany clouds and winds, and are in proportion to them, and +are all greatest where magnetic force is greatest. The barometer also +rises as the magnetic energy decreases. Do the magnetic currents, passing +upward with increased force, lift, elevate the atmosphere? How, then, are +we to explain the increased range of the oscillations, as the center of +atmospheric machinery is reached, where magnetism has least intensity, and +the perpendicular currents are less, and attraction is less? Attraction is +greatest where intensity is greatest, and there the barometer stands +highest, and the diurnal range is least. Is it then the attraction of +magnetism which produces the barometric oscillations? If so, how then can +we explain the diurnal fall while magnetism is most active? + +Perhaps we have not yet arrived at such a knowledge of the nature of +magnetism as is necessary to a correct answer of those questions. Faraday +has taught us that the lines of magnetic force are close curves, passing +into the atmosphere, and over to the opposite hemisphere, and returning +through the earth, out on the opposite side in like manner, and back +again, passing twice through the earth and twice through the atmosphere. +All we know of this is what the iron filings indicate, and we do not know +how much reliance to place upon the indications they give. But if Faraday +is right, the sun will, twice each day, intersect and stimulate into +increased activity the same closed magnetic curve--once when it is coming +out of the earth, during our day, when its influence will be the most +active, and once when it is returning on the opposite side of the earth; +and a second, but feebler magnetic and electric maximum, may be occasioned +by its action on the opposite and returning closed curve of the same +current. However this may be, it is exceedingly difficult to conceive, of +any adequate influence exerted by the tension of vapor. + +So the mid-day barometric minimum may be caused by the attraction of the +earth, in a state of increased magnetic activity and intensity, upon the +counter-trade, and its consequent approach or settling toward the earth. +Observation, as I have already said, pointedly indicates such a state of +things. So the increased magnetic activity, with or by its associate +electricity, acts upon the electricity of the counter-trade, condensation +takes place, the electricity is disturbed in the surface-atmosphere, by +induction, and its tension is changed. Opposite electrical conditions are +induced in the surface strata, and attraction takes place. The air moves +easily, and thus the attractions originate the winds. Secondary currents +are induced, as in all other cases of electric activity, and winds, in +_different strata_ and directions, occur, with or without cumulus, or scud +condensation, according to their activity, and the proportion of moisture +of evaporation they may contain. + +I am well aware that the various received theories of meteorology +attribute condensation to the action of cold, mingling of colder strata, +etc. But I think that view will have to be abandoned. + +It assumes that moisture is evaporated and held in the atmosphere by +latent heat, which is given out during condensation, and actually warms +the surrounding atmosphere. Thus, the Kew Committee undertook to explain +the development of greater heat, at the elevation where they, in fact, +found the counter-trade. But how unphilosophical to suppose a portion of +the air or vapor contained in it, can give out to another adjoining +portion _more heat than is necessary to produce an equilibrium_. This can, +indeed, be done by experiment--_but the experiment is made with currents +of electricity_. How unphilosophical, too, to talk of latent heat in +connection with evaporation, _at the lowest temperature known_. +Meteorologists must revise their opinions on the subject of condensation. +This latent heat has never been actually met with; on the contrary, the +most sudden and complete condensations of the vapor of the atmosphere are +attended by as sudden and extraordinary productions of cold, and +consequent hail, and the connection between condensation and electricity +is shown by too many facts to permit the old theory to stand. + +_Fog never forms with the thermometer below 32°._ It is mainly a _summer +condensation_, especially high fog. It has been attributed to the cooling +effect of an atmosphere colder than the earth, but it often occurs when +the earth is the coldest, and when the vapor, as it rises, is colder than +the air, and could not give out heat to a warmer medium. (See American +Journal of Science, vol. xliv. p. 40.) Again, it is not mere condensation, +but a formation of globules or vesicles, hollow, and the air expanded in +them, by means of which they float like a soap bubble which contains the +warm air of the breath. Is not every vesicle a model shower, positively +electrified on the outside, negatively in the center, or the reverse, +according to the strata, with the air expanded in the middle by the excess +of heat which negative electricity detains? Look at them, as they attach +themselves to the slender nap of the cloth you wear, when passing through +them, and see how many of them it would require to form a large drop of +rain. The clouds are of a similar vesicular character, and rain does not +fall till the vesicles unite to form drops. Sudden and extreme cold is +indeed produced in the hail-storm, when, above, below, and around it, the +temperature is unaffected. Testu, Wise, and other aeronauts, have so found +it, and the hail tells us it is so. But it is idle to say it results from +radiation. All the phenomena of the sudden, violent hail-storms are +electric in an extraordinary degree. The electricity is disturbed and +separated--the associated heat continues with the negative, and leaves the +positive portion of the cloud, and a corresponding reduction of +temperature results. So Masson found in his eudiometrical analytical +experiments the _negative_ wire would heat to fusion, while the positive +was cold. (See London, Edinburgh, and Dublin Journal of Science for +December, 1853.) This disturbed electricity is diffused over the vesicles. +Listen to the thousand _crackling_ sounds which initiate the clap of +thunder, and may be heard when the lightning strikes near you; produced by +the gathering of the lightning from as many points of the cloud where it +was diffused, to unite in one current and produce the "clap" or +"peal"--and to the "pouring" of the rain, which follows the union of the +vesicles, after the excess of repelling electricity is discharged. + +No _change_ of temperature is observed when fogs form, except the ordinary +change between night and day; and it seems perfectly obvious, in looking +at all the phenomena, that fogs form at a temperature of 70° or 75°, in +consequence of the electric influence of the earth upon the adjoining +surface-atmosphere; and, when formed, they withstand the most intense +action of a summer sun, till the time of day arrives for the barometric +and electric tension to fall, condensation to take place in the +counter-trade above, and wind to be induced. Who that has noticed the +almost blistering force of the solar rays, as they break through a section +of high fog, about 10 A.M., can forget them. + +Fogs form near the earth, during the night, when the atmosphere above is +loaded with moisture many degrees colder, and yet remains free from +condensation. On the other hand, during the heat of the day, and of the +hottest days, the heavy rains condense above--nay, they frequently fall at +a temperature of 75° to 80°, in the tropics, and of 50° to 55° in +mid-winter here. + +Thus far, an adherence to the opinion that condensation was simply a +cooling process; the driving out of its latent heat, not merely to another +body to make an equilibrium, but "_getting rid of it_" by positive active +radiation, or in some other way, so as to cool off and condense, has +involved the formation and classification of clouds in obscurity. Hopkins +(Atmospheric Changes, p. 331) laments this, but fettered by a false and +imperfect theory, in relation to the tension of vapor, he falls into a +similar error. + +Now, there are, as we have seen, peculiar, distinctly-marked varieties of +cloud, connected with peculiar and distinctly-marked conditions of the +atmosphere, _irrespective of temperature_. None of the theories advanced, +account, or profess to account for the differences in either. No +modification of the calorific theory will account for them. They differ in +shape, in color, in tendency to precipitation, in line of progress, and in +electrical character. The explanation of this is found in the fact, that +they form in distinct and different strata, partake of the positive +electric character of the one, or the negative of the other; or are +secondary, induced by the action of a primary condensation in a different +stratum. There is not any mingling of the different strata, as has been +supposed; and many other facts than those to which we have alluded, show +that the formation of cloud is a magneto-electric process. + +The observations of Reid show that every violent shower cloud has the +electricities disturbed, and portions of it are positive, and others +negative. Howard gives us the following _résumé_ of Reid's observations: + + "From an attentive examination of Reid's observations I have been + able to deduce the following general results: + + "1. _The positive electricity, common to fair weather, often yields + to a negative state before rain._ + + "2. _In general, the rain that first falls, after a depression of the + barometer, is_ NEGATIVE. + + "3. _Above forty cases of rain, in one hundred, give negative_ + electricity; although the state of the atmosphere is positive, before + and afterward. + + "4. _Positive rain, in a positive atmosphere, occurs more rarely_: + perhaps fifteen times in one hundred. + + "5. _Snow and hail, unmixed with rain, are positive, almost without + exception._ + + "6. _Nearly forty cases of rain, in one hundred, affected the + apparatus with both kinds_ of electricity; sometimes with an + interval, in which no rain fell; and so, that a positive shower was + succeeded by a negative; and, _vice versâ_; at others, the two kinds + alternately took place during the same shower; and, it should seem, + _with a space of non-electric rain between them_." + +Howard attributes, with great apparent probability, the successive +differences in the electrical character of the rain, to the passage of +different portions of the cloud, having different polarity, over the place +of observation. So _positive hail_, and _negative rain_ fall in _parallel +bands_ from the same cloud. Many such instances are on record. It should +be remembered that he is describing the phenomena in the showery climate +of England. + +But the most decisive, perhaps, as well as practically important evidence +of the influence of magnetism, or magneto-electricity, in meteorological +phenomena, is derived from the action of storms. My observation has been +limited, for my life has been, and must be, a practical one. But, subject +to future, and I hope speedy corroboration, or correction, by extensive +systematic observation, I think I may venture to divide all storms into +four kinds: + +1. Those which come to us from the tropics, and constitute the class +investigated by Mr. Redfield. That these are of a magneto-electric +character is evident. They originate near the line of magnetic intensity, +over, or in the vicinity of, the volcanic islands of the tropics; are +largely accompanied by electrical phenomena; extend laterally as they +progress north; induce and create a change of temperature in advance of +them, and do not abate until they pass off over the Atlantic to the E. or +N. E., and perhaps not until they reach the Arctic circle. Their extensive +and continued action is not owing to any mere _mechanical agency_ of the +adjoining passive air, or other supposed currents, originated, no man can +tell how, but they concentrate upon themselves the local magnetic currents +as they pass over and intersect them, and, by their inductive action upon +the surface-atmosphere, in different directions, attract it under them, +and within their more active influence. Here the action of the magnetic +currents is probably the primary cause, but the power of the storm to +concentrate upon itself the new magnetic currents which it intersects as +it enters each new, successive field, enables them to maintain and extend +their action. + +The following diagram illustrates the course and gradual enlargement of a +mid-autumn tropical storm, which induces a S. E. wind in front, and +occasions a thaw. + + +[Illustration: Fig. 20.] + + +2. Another class originate at the N. W., and extend gradually south +easterly on the magnetic meridian. These are most frequent in summer, +forming belts of showers, but occur, I believe, at all seasons of the +year. They seem to be produced by magnetic waves passing south, and are +followed in autumn and winter, and sometimes in summer, by the peculiar N. +W. wind and scud, and a term of cooler weather. + +Thus, it is believed that many, perhaps all of the alternating terms of +heat and cold, are dependent on magnetic waves passing over the country in +a similar manner, with a greater or less belt of condensation between +them, and depending on peculiar magnetic action traveling in the same +way. The S. E. extension of showers and storms, and the cooler changes of +temperature which immediately follow them; with light N. W. wind in +mid-summer, and with it fresher at earlier and later periods, in the form +of northers blowing violently, according to the season, are intimately +connected, and indicate such waves. The indication is strengthened also by +the frequent progress of auroras in like manner, occurring usually after +the belt of condensation has passed, and frequently following it. The +clouds and currents of the atmosphere, so far as I have been able to +discover, show no permanent current from the pole to the atmospheric +equator, compensating for the counter-trade; and that compensation is +furnished by the periodical but frequent atmospheric waves, connected with +the periodical changes of storm, and cloud, and sunshine, which gradually +extend from north to south, in or near the magnetic meridian. Perhaps such +compensating currents are found west of the magnetic poles, as we have +suggested, and make the N. E. and northerly dry winds of Western Europe +and the Pacific; but, in the present state of our knowledge, it is +impossible to say that they are. If it be so, the compensation they +furnish must be small; for the volume of counter-trade which is not +depolarized before it reaches the Arctic circle, and which passes round +the magnetic pole, must be very small. A majority of our periodical +changes, during the northern transit, and I believe at all seasons, are of +this character; and, I have reason to believe, from observation, in one +or two cases, that where belts of rains and showers begin, over _any +locality_ in the United States, they may assume this character. I have +been in Saratoga when an easterly storm commenced _south of that place_; +the condensation and mackerel sky being visible at the south, and no cloud +formation or rain occurring there at the time, and have traced it +afterward as a belt which had a lateral extension south-eastward. Leaving +that place immediately after a belt had passed south, I have overtaken it +by railroad, and run into it again before arriving at New York; and +witnessed its subsequent extension south-eastwardly, out over the +Atlantic. I have witnessed the approach of such a belt in the spring, at +Sandusky, upon Lake Erie, and its passage over to the S. E., followed by +the N. W. wind, as Mr. Bassnett describes them at Ottawa, and run under +the attenuated edge of the same belt, on the same day, on the way to +Pittsburg, leaving the N. W. wind behind, but finding it present again +with clear sky on the following morning. I have seen hundreds of them +approach from the north, and pass to S. E., out over the Atlantic; +followed by the N. W. wind in spring and autumn. This class of storms pass +off toward, and doubtless over the track, of our European steamers and +packets. I know this, for I witness it nearly every month in the year. It +is not a matter of speculation, but of actual, long-continued observation. +Probably, as one approaches the Gulf Stream, and when over it, its induced +winds may be more violent. It is time our navigators understood this; and +that all the gales of the North Atlantic, certainly, are not rotary; and +do not approach from the S. W. in the same manner as the class +investigated by Mr. Redfield do. Where a fresh southerly or south-westerly +wind is followed by any considerable cirro-stratus or stratus-condensation, +it is usually of this character. + +The following diagram exhibits the peculiarities of this class of storms. +It is intended to represent the same storm or belt of showers, on _two +successive_ days, and, of course, its usual rate of southerly extension: + + +[Illustration: Fig. 21.] + + +This class of storms, or belts of showers, present the following +succession of phenomena in summer: + +1. Still warm weather, one or more days. + +2. Fresh southerly wind, one or more days; if more than one, dying away at +the S. W., at night-fall, but continuing into the evening of the day +before the belt of condensation arrives. + +3. Belt of condensation, with or without rain or showers, with the +easterly wind blowing axially, if the condensation is heavy and the belt +wide; westerly if the condensation is feeble or the belt narrow--the +clouds moving about E. N. E. + +4. Cooler air, light N. W. in summer, heavy N. W. in autumn, winter, and +spring. + +And, the next period-- + +5. Still warm weather or light airs. + +6. Southerly wind, fresh. + +7. Belt of condensation. + +8. Cool northerly wind. + +And so on, successively, unless broken in upon by some other class. + +Sometimes these periods are exceedingly regular, at other times the other +classes prevail. I have much reason to believe that this is the _normal, +periodic_ provision for condensation of our portion of the northern +hemisphere, and probably of every other where rain falls regularly in the +summer season, and that the other classes are exceptions, as the +hurricanes are exceptions to the normal condition of the weather every +where. Perhaps in some seasons, during the northern transit, the +exceptions may equal the rule, but I do not now remember such a season. In +other years nearly all the storms are of this character. Thus, Dr. +Hildreth (in Silliman's Journal for 1827), speaking of the year 1826, in a +note to his register of that year, says: "There have been, this year, an +unusual number of winds from N. or N. W. Nearly every rain the past summer +has been followed with winds from the northward, when, in many previous +summers, the wind continued to the southward after rain." The immediate +occurrence of northerly wind after the passage of the belt of +condensation, is a peculiar feature of this class of storms. + +As this also will be new, and is of great practical interest, I shall be +pardoned for referring to other evidence. Bermuda is in latitude 32° +north. In the summer season they are within the range of the Calms of +Cancer, as Lieutenant Maury terms them, and not subject to storms. From +November to May, inclusive, they have successions of revolving wind. +Colonel Reid gave them much attention, and studied them barometrically: +that is, he studied the changes of the wind during the successive periodic +depressions. He found them revolving like ours, and hence inferred the +truth of the gyratory theory in relation to all winds. But it is perfectly +evident the same polar belts which pass over us reach them during the +southern transit. The precedent southerly wind, the _central +condensation_, the appearance of lightning, and the rotation of the wind +by both the east and west, but most frequently by west, are the same. In +his chapter on observations at the Bermudas, he gives us many examples. +Probably the existence of the Gulf Stream to the west and north has a +modifying influence upon them, and their action becomes less intense in +that latitude, but they are very similar. I copy a record of the weather, +for a month, which may be found on pages 252, 253, and 254, and a portion +of his remarks: + + "The month of December, 1839, presents a continual succession of + revolving winds passing over the Bermudas, with scarcely an + irregularity, as regards the fall and rise of the barometer + accompanying the veering of the wind. One, however, occurred on the + 10th and 11th. The S. W. wind abated, and changed to W. N. W., with + the barometer still falling. But in the column of remarks it is noted + that there was lightning seen in the N. and N. W., from 7 P.M., + during the night. This irregularity may, therefore, have been + occasioned by a gale passing over the banks of Newfoundland, + influencing the direction of the wind at Bermuda. + +"REVOLVING WINDS. + + +-----------------------------------------------------------------+ + | Date. | Hour. |Direction of| Wind's | Weather. | Bar.|Ther.| + | | | Wind. | Force. | | | | + |--------|---------|------------|--------|-----------|------|-----| + | 1839. | | | | | | | + |Nov. 30 |Midnight.| S. S. E. | 1 |b. c. | 30·06| 65 | + |Dec. 1 | Noon. | S. S. W. | 3 |b. c. | 30·07| 71 | + | 2 | " | S. W. | 5 |g. m. q. | 29·86| 70 | + | 3 | " | S. S. W. | 3 |g. c. | 29·76| " | + | 4 | " | S. W. | 6 |g. m. r. | 29·62| 68 | + | 5 | " | W. N. W. | 5 |p. q. | 29·56| " | + | 6 | " | N. W. | 6 |p. q. |*29·55| " | + | 7 | " | N. N. W. | 5 |b. c. | 29·78| 70 | + | " |Midnight.| N. N. W. | 3 |b. c. | 29·89| 68 | + | 8 | Noon. | W. N. W. | 2 |b. c. | 29·82| 71 | + | 9 | " | S. S. W. | 5 |p. q. | 29·84| 70 | + | 10 | " | S. W. | 2 |b. c. | 29·96| " | + | 11 | " | W. N. W. | 6 |b. c. m. |*29·88| 68 | + | 12 | " | S. S. W. | " |b. v. | 29·99| 69 | + | 13 | " | N. N. by W.| " |b. v. | 30·01| 66 | + | 14 | " | N. N. W. | 5 |b. c. v. | 30·06| 64 | + | " |Midnight.| N. W. | 2 |b. c. p. | 30·05| 63 | + | 15 | Noon. | S. W. by S.| 6 |g. m. r. | 29·72| 65 | + | " | P.M. 2 | S. S. W. | 7 |m. q. r. | 29·92| 64 | + | " | " 4 | S. S. W. | " |g. m. q. r.| 29·55| " | + | " | " 6 | W. S. W. | " |q. w. |*29·53| " | + | " | " 8 | N. W. | 6 |b. c. q. | 29·54| " | + | " | " 10 | N. N. W. | " |b. c. | 29·55| " | + | 16 | Noon. | N. W. | 7 |b. c. m. | 29·53| 62 | + | 17 | " | N. W. by N.| " |p. q. | 29·67| 60 | + | 18 | " | N. W. | 6 |c. q. | 29·86| " | + | 19 | " | N. W. by N.| 7 |m. q. r. |*29·73| 59 | + | 20 | " | N. N. W. | " |p. q. c. | 29·89| 58 | + | 21 | " | N. W. by N.| 6 |c. q. | 29·96| 56 | + | " |Midnight.| S. W. | 1 |b. c. | 29·95| 55 | + | 22 | Dawn. | ---- | 0 | | | | + | " | Noon. | S. S. W. | 5 |g. m. | 29·83| 56 | + | " | P.M. 4 | S. | 7 |g. m. | 29·79| " | + | " | " 6 | S. S. E. | " |g. m. r. | 29·61| " | + | " | " 8 | S. S. E. | " |w. r. | 29·52| " | + | " | " 10 | S. E. | " |m. w. r. | 29·48| " | + | 23 | Noon. | S. W. | 6 |b. c. m. |*29·44| 57 | + | 24 | " | W. N. W. | " |b. m. | 29·71| 59 | + | 25 | " | W. N. W. | 5 |b. c. | 29·88| 56 | + | 26 | " | N. | 3 |c. | 30·09| 62 | + | 27 | " | S. E. | 5 |c. q. r. | 30·07| 61 | + | 28 | " | S. W. | 6 |c. q. | 29·88| 66 | + | " |Midnight.| S. S. W. | " |b. c. | 29·76| 65 | + | 29 | Noon. | S. W. | 7 |c. b. |*29·48| 64 | + | 30 | " | W. N. W. | 6 |b. c. q. | 29·83| 55 | + | 31 | " | N. W. | 5 |b. c. | 30·12| 58 | + +-----------------------------------------------------------------+ + + "_Remark printed in the Register._ + + "The changes of the wind during the December gales have been nearly + the same in all: _i. e._, commencing with a southerly wind at first, + the wind has veered by the west, toward the north-west, sometimes + ending as far round as N. N. W." + +These extracts show the passage of several successive belts, each with the +phenomena in regular order. + +The first commences with blue sky and detached clouds, barometer up, +thermometer down to 65°, and nearly calm, on the 30th of November. + +Dec. 1 (at noon). Wind freshens from S. S. W.; thermometer rises; +barometer still up. + +Dec. 2. Barometer has fallen; thermometer up; wind increasing from S. W., +with gloomy, squally appearance. + +Dec. 3. Wind S. S. W.; barometer slowly falling; thermometer slightly. + +Dec. 4. Wind fresh; S. W.; condensation and rain has reached them, and it +carries barometer and thermometer down. + +Dec. 5. Wind shifting by the west, and squally. + +Dec. 6. Winds gets N. W.; blows fresh; barometer at its minimum, probably +at the time of the change of wind, although the register does not show the +precise time. + +Dec. 7. Wind N. N. W.; blue sky and detached clouds (N. W. scud), cleared +off; barometer elevated by the N. W. wind, from 29.55 to 29.78. Midnight: +blue sky; detached clouds (N. W. scud probably); barometer up to 29.89; +thermometer fallen, from the cooler character of the northerly wind. + +Dec. 8. Wind having lulled as a northerly wind has got round to S. W. +again; thermometer up; barometer falling, and another belt approaching, +and so on. + +The first and last part of December show each two regular occurrences of +substantially the same phenomena. The middle is somewhat more irregular. + +There were five distinctly-marked periods, and one squally, long-continued +period, with a slight tendency to condensation, and a slight fall of +barometer and rain on the 19th (N. W. squall probably), but not sufficient +to reverse the wind to the south. In Colonel Reid's opinion there were +five revolving gales which passed over Bermuda during the month. In my +opinion, there were five perfect polar waves of condensation, and one +imperfect one, with as many successive southerly winds preceding the +condensation, with or without rain in the center, followed by as many cold +N. W. or N. N. W. winds, with squalls, in the rear, about five days apart. +(See the * in the barometric column.) + +_We are at issue._ Let the question be determined by _actual observation_, +and not by _speculation_. It is of fundamental and exceeding importance to +the science. + +Now, let us take a month in summer, from the observations of Mr. Bassnett, +at Ottawa. Here the climate differs somewhat from that east of the +Alleghanies; the magnetic intensity is greater, and the action more +violent and irregular. That part of the country, it should be remembered, +has a greater fall of rain in summer, for reasons we have stated, and +those periodic revolutions are more frequent. + + "A brief abstract from a journal of the weather for one sidereal + period of the moon, in 1853. + + "_June_ 21st. Fine clear morning (S. fresh): noon very warm 88°; 4 + P.M., plumous _cirri in south_; ends clear. + + "22d. Hazy morning (S. very fresh) arch of cirrus in west; 2 P.M., + black in W. N. W.; 3 P.M., overcast and rainy; 4 P.M., a heavy gust + from south; 4.30 P.M., blowing furiously (S. by W.); 5 P.M., + tremendous squall, uprooting trees and scattering chimneys; 6 P.M., + more moderate (W.). + + "23d. Clearing up (N. W.); 8 A.M., quite clear; 11 A.M., bands of + mottled cirri pointing N. E. and S. W., ends cold (W. N. W.); the + cirri seem to rotate from left to right, or with the sun. + + "24th. Fine clear, cool day, begins and ends (N. W.). + + "25th. Clear morning (N. W. light); 2 P.M. (E.), calm; tufts of + tangled cirri in north, intermixed with radiating streaks, all + passing eastward; ends clear. + + "26th. Hazy morning (S. E.), cloudy; noon, a heavy, windy-looking + bank in north (S. fresh), with dense cirrus fringe above, on its + upper edge; clear in S. + + "27th. Clear, warm (W.); bank in north; noon bank covered all the + northern sky, and fresh breeze; 10 P.M., a few flashes to the + northward. + + "28th. Uniform dense cirro-stratus (S. fresh); noon showers all + round; 2 P.M., a heavy squall of wind, with thunder and rain (S. W. + to N. W.); 8 P.M., a line of heavy cumuli in south; 8.30 P.M., a very + bright and high cumulus in S. W., protruding through a layer of dark + stratus; 8.50 P.M., the cloud bearing E. by S., with three rays of + electric light. + + "29th. A stationary stratus over all (S. W. light); clear at night, + but distant lightning in S. + + "30th. Stratus clouds (N. E. almost calm); 8 A.M., raining gently; 3 + P.M., stratus passing off to S.; 8 P.M., clear, pleasant. + + "_July_ 1st. Fine and clear; 8 A.M., cirrus in sheets, curls, wisps, + and gauzy wreaths, with patches beneath of darker shade, all nearly + motionless; close and warm (N. E.); a long, low bank of haze in S., + with one large cumulus in S. W., but very distant. + + "2d. At 5 A.M., overcast generally, with hazy clouds and fog of + prismatic shades, chiefly greenish-yellow; 7 A.M. (S. S. E. + freshening), thick in W.; 8 A.M. (S. fresh), much cirrus, thick and + gloomy; 9 A.M., a clap of thunder, and clouds hurrying to N.; a + reddish haze all around; at noon the margin of a line of + yellowish-red cumuli just visible above a gloomy-looking bank of haze + in N. N. W. (S. very fresh); warm, 86°; more cumuli in N. W.; the + whole line of cumuli N. are separated from the clouds south by a + clearer space. These clouds are borne rapidly past the zenith, but + never get into the clear space--they seem to melt or to be turned off + N. E. The cumuli in N. and N. W., slowly spreading E. and S.; 3 P.M., + the bank hidden by small cumuli; 4 P.M., very thick in north, + magnificent cumuli visible sometimes through the breaks, and beyond + them a dark, watery back-ground (S. strong); 4.30 P.M., wind round to + N. W. in a severe squall; 5 P.M., heavy rain, with thunder, etc.--all + this time there is a bright sky in the south visible through the rain + 15° high; 7 P.M., clearing (S. W. mod.). + + "3d. Very fine and clear (N. W.); noon, a line of large cumuli in N., + and dark lines of stratus below, the cumuli moving eastward; 6 P.M., + their altitude 2° 40'. Velocity, 1° per minute; 9 P.M., much + lightning in the bank north. + + "4th. 6 A.M., a line of small cumulo-stratus, extending east and + west, with a clear horizon north and south 10° high. This band seems + to have been thrown off by the central yesterday, as it moves slowly + south, preserving its parallelism, although the clouds composing it + move eastward. Fine and cool all day (N. W. mod.)--lightning in N. + + "5th. Cloudy (N. almost calm), thick in E., clear in W.; same all + day. + + "6th. Fine and clear (E. light); small cumuli at noon; clear night. + + "7th. Warm (S. E. light); cirrus bank N. W.; noon (S.) thickening in + N.; 6 P.M., hazy but fine; 8 P.M., lightning in N.; 10 P.M., the + lightning shows a heavy line of cumuli along the northern horizon; + calm and very dark, and incessant lightning in N. + + "8th. Last night after midnight commencing raining, slowly and + steadily, but leaving a line of lighter sky south; much lightning all + night, but little thunder. + + "8th. 6 A.M., very low scud (500 feet high) driving south, still calm + below (N. light); 10 A.M., clearing a little; a bank north, with + cirrus spreading south; same all day; 9 P.M., wind freshening (N. + stormy); heavy cumuli visible in S.; 10.30 P.M., quite clear, but a + dense watery haze obscuring the stars; 12 P.M., again overcast; much + lightning in S. and N. W. + + "9th. Last night (2 A.M. of 9th) squall from N. W. very black; 4 + A.M., still raining and blowing hard, the sky a perfect blaze, but + very few flashes reach the ground; 7 A.M., raining hard; 8 A.M. (N. + W. strong); a constant roll of thunder; noon (N. E.); 2 P.M. (N.); 4 + P.M., clearing; 8 P.M., a line of heavy cumuli in S., but clear in N. + W., N., and N. E. + + "10th. 3 A.M., Overcast, and much lightning in south (N. mod.); 7 + A.M., clear except in south; 6 P.M. (E.); 10 P.M., lightning south; + 11 P.M., auroral rays long, but faint, converging to a point between + Epsilon Virginis and Denebola, in west; low down in west, thick with + haze; on the north the rays converged to a point still lower; + lightning still visible in south. This is an aurora in the west. + + "11th. Fine, clear morning (N. E.); same all day; no lightning + visible to-night, but a bank of clouds low down in south, 2° high, + and streaks of dark stratus below the upper margin. + + "12th. Fine and clear (N. E.); noon, a well-defined arch in S. W., + rising slowly; the bank yellowish, with prismatic shades of + greenish-yellow on its borders. This is the O. A. At 6 P.M., the bank + spreading to the northward. At 9 P.M., thick bank of haze in north, + with bright auroral margin; one heavy pyramid of light passed through + Cassiopeia, traveling _westward_ 1-1/2° per minute. This moves to the + other side of the pole, but not more inclined toward it than is due + to prospective, if the shaft is very long; 11.10 P.M., saw a mass of + light more diffuse due east, reaching to _Markab_, then on the prime + vertical. It appears evident this is seen in profile, as it inclines + downward at an angle of 10° or 12° from the perpendicular. It does + not seem very distant. 12 P.M., the aurora still bright, but the + brightest part is now west of the pole, before it was east. + + "13th. 6 A.M., clear, east and north; bank of cirrus in N. W., _i. + e._, from N. N. E. to W. by S.; irregular branches of cirrus clouds, + reaching almost to south-eastern horizon; wind changed (S. E. fresh); + 8 A.M., the sky a perfect picture; heavy regular shafts of dense + cirrus radiating all around, and diverging from a thick nucleus in + north-west, the spaces between being of clear, blue sky. The shafts + are rotating from north to south, the nucleus advancing eastward. + + "At noon (same day), getting thicker (S. E. very fresh); 6 P.M., moon + on meridian, a prismatic gloom in south, and very thick stratus of + all shades; 9 P.M., very gloomy; wind stronger (S. E.); 10 P.M., very + black in south, and overcast generally. + + "14th. Last night, above 12 P.M., commenced raining; 3 A.M., rained + steadily; 7 A.M., same weather; 8.20 A.M., a line of low storm-cloud, + or scud, showing very sharp and white on the dark back-ground all + along the southern sky. This line continues until noon, about 10° at + the highest, showing the northern boundary of the storm to the + southward; 8 P.M., same bank visible, although in rapid motion + eastward; same time clear overhead, with cirrus fringe pointing north + from the bank; much lightning in south (W. fresh); so ends. + + "15th. Last night a black squall from N. W. passed south without + rain; at 3 A.M., clear above but, very black in south (calm below all + the time); 9 A.M., the bank in south again throwing off rays of cirri + in a well-defined arch, whose vortex is south; these pass east, but + continue to form and preserve their linear direction to the north; no + lightning in south to-night. + + "16th. Clear all day, without a stain, and calm. + + "17th. Fine and clear (N. E. light); 6 P.M., calm. + + "18th. Fair and cloudy (N. E. light); 6 P.M., calm. + + "19th. Fine and clear (N. fresh); I. V. visible in S. W. + + "20th. 8 A.M., bank in N. W., with beautiful cirrus radiations; 10 + A.M., getting thick, with dense plates of cream-colored cirrus + visible through the breaks; gloomy looking all day (N. E. light)." + +The letters in a parenthesis signify the direction of the wind. + +During this month there were three distinctly marked periods of belts of +showers, preceded by "fresh" or "strong" south wind, and followed by the +N. W. There was a period when a belt of less intense stratus, without much +wind, occurred (28th, 29th, and 30th of June). This was followed by a +distinct belt of showers and _fresh_ S. wind, on the 2d of July, and by +the N. W. wind and clear weather, on the 3d. + +During the rest of July it was more irregular, with the exception of the +7th, 8th, and 9th, when another belt and revolution occurred. + +Now, these periods, when distinctly marked, exhibit the same succession of +phenomena--viz., elevation of temperature, fresh southerly wind, belt of +condensation, cumulus or stratus with cirrus running east, but extending +south, followed by N. W. wind, and clear, cold air. Can any one believe +they were successive rotary gales? + +I wish, in this connection, to make a suggestion to Lieutenant Maury and +others. The descriptions of M. Bassnett, although not perfect, are very +intelligible. He describes things as they were, and as they should be +described. He distinguishes the clouds, and the scud, and other +appearances. + +But Colonel Reid's descriptions are unmeaning and unintelligible. G. +M.--Gloomy, misty! Gloomy from what? fog, or stratus, or a stratum of +scud, or what? We can not know. Again, C. The table tells us this stands +for detached clouds. But of what kind? Cumulus, broken stratus, patches of +cirro-cumulus or cirro-stratus, or scud? All these, and indeed every kind +of cloud or fog formation, except low fog, may exist in detached portions. + +These abbreviations will not answer; they do not describe the weather. The +clouds must be studied and described. There is no difficulty in doing it. +Sailors will learn them very soon after their teachers have; and those who +teach them should see to it that the logs contain terms of description +which convey the meaning which may, and ought to be, conveyed. The use of +these indefinite terms can not be continued without culpability. + +Again, the observations of seamen off our coast are in accordance with the +progress of this class of storms on land, and prove that they continue S. +E. over the Atlantic, abating in action as they approach the tropics. +There is abundant evidence of this in the work of Colonel Reid, and the +charts of Lieutenant Maury, but I can not devote further space to them. + +The third class form in the counter-trade, over some portion of the +country, from excessive volume or action of the counter-trade, or local +magnetic activity, without coming from the tropics or being connected with +a regular polar wave of magnetic disturbance. + +The following diagram exhibits their form, progress, and accompanying +induced winds. + + +[Illustration: Fig. 22.] + + +The gentle rains of spring, particularly April, and the moderate and +frequent snow-storms of winter, are often of this character; and so are +the heavy rains, which commence at the morning barometric minimum, rain +heavily through the forenoon, and light up near mid-day in the south, +followed by gentle, warm, S. W. winds. This class are more frequent in +some years than others--probably the early years of the decade, while +polar storms are, during the later ones. It is this class which have +_violent_ easterly winds _in front_, and on the _south side_, with two or +more currents, and which Mr. Redfield has also supposed to be cyclones. + +The fourth class are isolated showers, occurring over particular +localities, or belts of drought and showers alternating; sometimes a +general disposition to cloudy and showery weather for a longer or shorter +interval over the whole country; at others, limited to particular +localities in the course of the trade. Such a period occurred during the +wheat harvest of 1855. This class I attribute to a general increased +magnetic action, but it may be induced by an increased volume, or greater +south polar magnetic intensity of the counter-trade, exciting and +concentrating the regular currents of the field, and increasing their +activity and energy. These also often work off south gradually, and are +followed by a cold N. W. air for a day or two; showing a tendency, in the +excited magnetism, to pass as a wave toward the tropics. + +The following diagram will give some idea of this class: + + +[Illustration: Fig. 23.] + + +There are sometimes very obvious local tendencies to precipitation over +portions adjoining an area affected with drought, as there are other +magnetic irregularities over particular areas. + +All these classes of storms are variant in intensity. Sometimes the +general or local cloud-formation is weak, and does not produce +precipitation at all; so of that which extends southerly. Probably the +tropical storm are always sufficiently dense and active to precipitate. +Their action is often violent over particular localities, and hence the +more frequent occurrence of the tornado over the more intense area of +Ohio, and other portions of the west. All violent local storms are +doubtless owing to local magneto-electric activity. + + + + +CHAPTER XI. + + +The reader who has attentively perused and considered the facts stated, +and the principles deduced, in the preceding pages, and is ready to make a +practical application of them by careful observation, will have little +difficulty in understanding the varied atmospheric conditions; and will +soon be able to form a correct judgment of the immediate future of the +weather, so far as his limited horizon will permit. + +But there are other facts and considerations, not specifically alluded to, +which will materially aid him in his observations; and there is a degree +of philosophical truth in the proverbs and signs, which ancient popular +observation accumulated, and poetry and tradition have preserved, that +meteorologists have been slow to discover or admit, but which will be +obvious upon examination, and commend them to his attention. + +The classical reader is doubtless familiar with that part of the first +Georgic of Virgil, which contains a description of the signs indicative of +atmospheric changes. Much of it is beautifully poetic, and, if read in the +light of a correct philosophy, is equally truthful. + +I copy from a creditable translation, found in the first volume of +Howard's "Climate of London": + + "All that the genial year successive brings, + Showers, and the reign of heat, and freezing gales, + Appointed signs foreshow; the Sire of all + Decreed what signs the southern blast should bring, + Decreed the omens of the varying moon: + That hinds, observant of the approaching storm, + Might tend their herds more near the sheltering stall." + + + PROGNOSTICS.--_1st. Of Wind._ + + "When storms are brooding--in the leeward gulf + Dash the swell'd waves; the mighty mountains pour + A harsh, dull murmur; far along the beach + Rolls the deep rushing roar; the whispering grove + Betrays the gathering elemental strife. + Scarce will the billows spare the curved keel; + For swift from open sea the cormorants sweep, + With clamorous croak; the ocean-dwelling coot + Sports on the sand; the hern her marshy haunts + Deserting, soars the lofty clouds above; + And oft, when gales impend, the gliding star + Nightly descends athwart the spangled gloom, + And leaves its fire-wake glowing white behind. + Light chaff and leaflets flitting fill the air, + And sportive feathers circle on the lake." + + + _2d. Of Rain._ + + "But when grim Boreas thunders; when the East + And black-winged West, roll out the sonorous peal, + The teeming dikes o'erflow the wide champaign, + And seamen furl their dripping sails. The shower, + Forsooth, ne'er took the traveler unawares! + The soaring cranes descried it in the vale, + And shunn'd its coming; heifers gazed aloft, + With nostrils wide, drinking the fragrant gale; + Skimm'd the sagacious swallow round the lake, + And croaking frogs renew'd their old complaint. + Oft, too, the ant, from secret chambers, bears + Her eggs--a cherished treasure--o'er the sand, + Along the narrow track her steps have worn. + High vaults the thirsty bow; in wide array + The clamorous rooks from every pasture rise + With serried wings. The varied sea-fowl tribes, + And those that in Cäyster's meadows seek, + Amid the marshy pools, their skulking prey, + Fling the cool plenteous shower upon their wings, + Crouch to the coming wave, sail on its crest, + And idly wash their purity of plume. + The audacious crow, with loud voice, hails the rain + A lonesome wanderer on the thirsty sand. + Maidens that nightly toil the tangled fleece, + Divine the coming tempest; in the lamp + Crackles the oil; the gathering wick grows dim." + + + _3d. Of Fair Weather._ + + "Nor less, by sure prognostics, mayest thou learn + (When rain prevails), in prospect to behold + Warm suns, and cloudless heavens, around thee smile. + Brightly the stars shine forth; Cynthia no more + Glimmers obnoxious to her brother's rays; + Nor fleecy clouds float lightly through the sky. + The chosen birds of Thetis, halcyons, now + Spread not their pinions on the sun-bright shore; + Nor swine the bands unloose, and toss the straw. + The clouds, descending, settle on the plain; + While owls forget to chant their evening song, + But watch the sunset from the topmost ridge. + The merlin swims the liquid sky, sublime, + While for the purple lock the lark atones: + Where she, with light wing, cleaves the yielding air, + Her shrieking fell pursuer follows fierce-- + The dreaded merlin; where the merlin soars, + _Her_ fugitive swift pinion cleaves the air. + And now, from throat compressed, the rook emits, + Treble or fourfold, his clear, piercing cry; + While oft amid their high and leafy roosts, + Bursts the responsive note from all the clan, + Thrill'd with unwonted rapture--oh! 'tis sweet, + When bright'ning hours allow, to seek again + Their tiny offspring, and their dulcet homes. + Yet deem I not, that heaven on them bestows + Foresight, or mind above their lowly fate; + But rather when the changeful climate veers, + Obsequious to the humor of the sky; + When the damp South condenses what was rare, + The dense relaxing--or the stringent North + Rolls back the genial showers, and rules in turn, + The varying impulse fluctuates in their breast: + Hence the full concert in the sprightly mead-- + The bounding flock--the rook's exulting cry." + + + _4th. The Moon's Aspects, etc._ + + "Mark with attentive eye, the rapid sun-- + The varying moon that rolls its monthly round; + So shalt thou count, not vainly, on the morn; + So the bland aspect of the tranquil night + Will ne'er beguile thee with insidious calm. + When Luna first her scatter'd fires recalls, + If with blunt horns she holds the dusky air, + Seamen and swains predict th' abundant shower. + If rosy blushes tinge her maiden cheek, + Wind will arise: the golden Phoebe still + Glows with the wind. If (mark the ominous hour!) + The clear fourth night her lucid disk define, + That day, and all that thence successive spring, + E'en to the finished month, are calm and dry; + And grateful mariners redeem their vows + To Glaucus, Inöus, or the Nereid nymph." + + + _5th. The Sun's Aspects, etc._ + + "The sun, too, rising, and at that still hour, + When sinks his tranquil beauty in the main, + Will give thee tokens; certain tokens all, + Both those that morning brings, and balmy eve. + When cloudy storms deform the rising orb, + Or streaks of vapor in the midst bisect, + Beware of showers, for then the blasting South + (Foe to the groves, to harvests, and the flock), + Urges, with turbid pressure, from above. + But when, beneath the dawn, red-fingered rays + Through the dense band of clouds diverging, break, + When springs Aurora, pale, from saffron couch, + Ill does the leaf defend the mellowing grape; + Leaps on the noisy roof the plenteous hail, + Fearfully crackling. Nor forget to note, + When Sol departs, his mighty day-task done, + How varied hues oft wander on his brow; + Azure betokens rain: the fiery tint + Is Eurus's herald; if the ruddy blaze + Be dimm'd with spots, then all will wildly rage + With squalls and driving showers: on that fell night, + None shall persuade me on the deep to urge + My perilous course, or quit the sheltering pier. + But if, when day returns, or when retires, + Bright is the orb, then fear no coming rain: + Clear northern airs will fan the quiv'ring grove. + Lastly, the sun will teach th' observant eye + What vesper's hour shall bring; what clearing wind + Shall waft the clouds slow floating--what the South + Broods in his humid breast. Who dare belie + The constant sun?" + +I copy also the following from Howard: + + "Dr. Jenner's signs of rain--an excuse for not accepting the + invitation of a friend to make a _country_ excursion. + + "The hollow winds begin to blow, + The clouds look black, the glass is low, + The soot falls down, the spaniels sleep, + And spiders from their cobwebs creep. + Last night the sun went pale to bed, + The moon in halos hid her head, + The boding shepherd heaves a sigh, + For see! a rainbow spans the sky. + The walls are damp, the ditches smell; + Closed is the pink-eyed pimpernel. + Hark! how the chairs and tables crack; + Old Betty's joints are on the rack. + Loud quack the ducks, the peacocks cry; + The distant hills are looking nigh. + How restless are the snorting swine!-- + The busy flies disturb the kine. + Low o'er the grass the swallow wings; + The cricket, too, how loud it sings! + Puss, on the hearth, with velvet paws, + Sits smoothing o'er her whisker'd jaws. + Through the clear stream the fishes rise + And nimbly catch the incautious flies; + The sheep were seen, at early light, + Cropping the meads with eager bite. + Though _June_, the air is cold and chill; + The mellow blackbird's voice is still; + The glow-worms, numerous and bright, + Illumed the dewy dell last night; + At dusk the squalid toad was seen, + Hopping, crawling, o'er the green. + The frog has lost his yellow vest, + And in a dingy suit is dress'd. + The leech, disturbed, is newly risen + Quite to the summit of his prison. + The whirling wind the dust obey + And in the rapid eddy plays. + My dog, so altered in his taste, + Quits mutton-bones, on grass to feast; + And see yon rooks, how odd their flight! + They imitate the gliding kite: + Or seem precipitate to fall, + As if they felt the piercing ball. + 'Twill surely rain; I see, with sorrow, + Our jaunt must be put off to-morrow." + +Howard attributes the foregoing to Jenner; but Hone, in his "Every-Day +Book," attributes it to Darwin, and gives it, with several couplets, not +found in that attributed to Jenner. These I add from Hone, as follows: + + "Her corns with shooting pains torment her-- + And to her bed untimely send her." + +That couplet is included by Hone with what is said of Aunt Betty. + + "The smoke from chimneys right ascends, + Then spreading back to earth it bends. + The wind unsteady veers around; + Or, settling in the south is found." + +Those are as philosophically accurate and valuable as any. + + "The tender colts on back do lie; + Nor heed the traveler passing by. + In fiery red the sun doth rise, + Then wades through clouds to mount the skies." + +The first of those couplets is untrue. It is doubtless alluded to as one +of the acts of the animal creation, indicating sleepiness and inaction, +which precede storms; but colts do not lie on the back. The other couplet +is both true and important. This collection entire, whether written by +Darwin or Jenner, contains most of the signs which have been preserved, +and which are of much practical importance in our climate. + +It is unquestionably true that "appointed signs foreshow the weather," to +a great extent, every where, but with more certainty in the climate in +which Virgil wrote than in our variable and excessive one. "Showers" and +"freezing gales" we can, perhaps, as well understand; but the "_reign of +heat_," by which he probably meant the dry period, when the southern edge +of the extra-tropical belt of rains is carried up to the north of them, we +do not experience. Something like it we did indeed have, during the +excessive northern transit, in the summer of 1854; but it was an +exception, not the rule. + +Some of the most important of those signs from Virgil and Jenner I propose +to allude to in detail; but it is necessary to look; in the first place, +to the character of the season and the month. + +We have seen that the years differ during different periods of the same +decade. That they incline to be hot and irregular during the early part of +it, and cool, regular, and productive during the latter portion--subject, +however, to occasional exceptions. The latter half of the third decade of +this century (1826 to 1830, inclusive) was comparatively warm; and, in the +latitude of 41°, was very unhealthy, and so continued during the early +part of the next, over the hemisphere, embracing the _cholera seasons_. +The spots upon the sun were much less numerous than usual, during the +latter half of the third decade. Thus the spots from + + 1826 to 1830, inclusive, were 873 + 1836 to 1840 " " 1201 + 1846 to 1850 " " 1168 + + and the size of those from 1836 to 1840 exceeded those of the other + years. + +The attentive observer will very soon be satisfied that the seasons have a +character; and those of every year differ in a greater or less degree from +those of other years in the same decade, and those of one decade not +unfrequently from those of some other. _Periodicity_ is stamped upon all +of them, and upon all resulting consequences. Like seasons come round, +and, like productiveness or unproductiveness, healthy or epidemic +diatheses, attend them. We have seen that, in relation to mean +temperature, there are such periodical diversities, but they are more +strongly marked in the character of storms, and other successions of +phenomena. "_All signs fail in a drouth_," for then all attempts at +condensation are partial, imperfect, and ineffectual. "_It rains very +easy_," it is said, at other times, and so it seems to do, and with +comparatively little condensation. In the one case, no great reliance can +be placed upon indications which are entirely reliable in the other. So +"_all our storms clear off cold_," or, "_all our storms clear off warm_," +are equally common expressions--as the _prevailing classes_ of storms give +a _character_ to the _seasons_. It "_rains every Sunday now_," is +sometimes said, and is often peculiarly true--the storm waves having just +then a weekly or semi-weekly period, and one falls upon Sunday for several +successive weeks; and when it is so, _that_ coincidence is sure to be +noticed and commented upon, and the other perhaps disregarded. + +If the seasons depended upon the northward and southward journey of the +sun alone, entire regularity might be expected--for we have no reason to +believe that magnetism and electricity contain, within themselves, +inherently, any tendency to irregularity, or periodicity; and, the sun +being constant in his _periods_, would be constant in his _influence_. But +he is inconstant and variable in his influence, and it is apparently +traceable to the existence of spots; but I am not quite sure that it is +occasioned by the _observable_ spots alone. Grant that the intensity and +power of his rays differ on the same day, in different years, and that +difference may be attributable in part to causes which our telescopes can +not discover. + +But the differences in the seasons do not depend on the variability of the +sun's influence alone. This appears from the frequent meridional and +latitudinal diversities and contrasts, to which allusion has been made. +The sun can not be supposed to exert a _less_ influence on a middle, than +a more northern latitude; nor on one series of meridians, than another. +There must, therefore, be another local and powerful disturbing cause, +varying the magnetic and electric activity and influence upon the trades, +as well in their incipiency as in their circuits, and thus controlling the +atmospheric conditions locally and in _the opposite hemispheres_. That +other disturbing cause is _volcanic action_. We can conceive of none +other, and we can detect and trace the influence of that to a considerable +extent. Unfortunately we know, and can practically know, comparatively +little of it. It has been busy with the earth since the creation, and will +continue to be so till, possibly, by a collision, it shall burst into +asteroids--its molten interior flowing out in seeming combustion--each +fragment retaining its magnetic polarities entire, and continuing on in an +independent orbit in the heavens, an asteroid, or meteorite. + +While, therefore, the agency of magnetism in itself may be regular, and +the transit of the sun is regular, and "seed-time and harvest shall not +cease," yet the sun is not regular in his influence, and the magnetic +agency is disturbed by another and irregular power. And, although we can +trace the influence of both upon the seasons, we can not measure that +influence, and from it reliably foretell the weather. The discoveries of +Swabe, and future ones, relative to solar irregularities, will assist us, +but, till we understand better, and to some extent anticipate, the +changes of volcanic action, we shall not be able to understand or foresee +all the differences in the seasons. That time may come; for progress is +yet to be read in the front of meteorology, and simultaneous practical +observations made and interchanged at every important point on the globe. +Nevertheless, the seasons have a character--often a regular one--one class +of storms prevailing over all others--one series of phenomena occurring to +the exclusion of others--and we must regard it if we would arrive at +intelligent estimates of their future condition. + +The most difficult part to understand are the meridional contrasts. Last +year we had one of the worst drouths which has occurred since the +settlement of the country. But while all the eastern portion of the United +States was dry, New Mexico was unusually wet; and the North-western +States, on the same curving line of the counter-trade, were not affected +by the drouth. + +Extract from a letter written by Governor Merriweather, to Mr. Bennett, in +answer to a circular, published in the "New York Herald," and dated + + "SANTA FE, NEW MEXICO, Oct. 25th, 1854. + + "More rain has fallen during the last six months, within this + territory, than ever was known to have fallen in the same length of + time, in this usually dry climate. Generally, little or no crops have + been produced without irrigation; but this season some good crops + have been produced without any artificial watering." + +We have seen that there was an apparent connection between the remarkable +volcanic action, exerted beneath the western continents during the second +decade of this century, and the remarkable coldness of that decade. And +it is easy to see that the comparative absence of volcanic action from +immediately beneath the Old World, and its presence in great excess +beneath the New, may disturb the regular action of terrestrial magnetism +above it in the earth's-crust here, and affect seasons, diatheses, and +health unfavorably; while from its absence they may be favorably affected +there. I have some general views in relation to this, but they are +necessarily speculative, for the data are few, and I reserve them. + +I am, however, induced to believe that the transit of the atmospheric +machinery is greater over some portions of the northern hemisphere, in +some seasons, than others. The most natural explanation of the unusual +contrast between the drouth of the Eastern States, and the wet of the +Territories, during the last summer, is, that the concentrated +counter-trade was carried west, by some irregular magnetic action in the +South Atlantic or West Indies. But there was much evidence that the +northern extension of the atmospheric machinery was greater than usual. +The transit began _early_--it was evidently _rapid_; the rains of May fell +in April, and the spring was wet; _summer set in earlier_--all the +appearances then were unusually tropical--the polar belts of condensation +descended upon us, but they were feeble, as they doubtless become, when +they reach the tropics, and did not precipitate; the summer continued full +twenty days later--no rain falling till about the 10th of September. The +season throughout was excessive, but otherwise regular. Spring came +earlier; summer commenced earlier and continued longer; autumn held off +later, and cold weather, when it came, was uniform and severe. This season +the transit has seemed to be less than for several years.[10] The spring +was backward; the summer cool, but exceedingly regular; the autumn thus +far without extremes, and the whole year healthy and productive. It is the +normal period of the decade, between the irregular heat of the first part, +and the irregular cold of the last; and it has been normal in character, +and conformed beautifully to its location. If the transit of 1854 was +further north than the mean, as it seemed to be over this country, that of +itself would convey the showers which follow up in the western portion of +the concentrated trade, on the east of the mountains of Mexico, and cause +them to precipitate further north, over New Mexico, and thus, rather than +from a diverted trade, they may have derived their unusual supply of +moisture during the summer of 1854. On this subject I can but conjecture, +and leave to future observation a discovery of the truth. + +Enough appears, however, to show the importance of taking the location of +the year in the decade, and even the character of the decade itself, into +the account. + +But whatever the remote cause of the difference in the seasons, the +character of the seasons is directly influenced by the character of +storms, or periodic changes. Sometimes the tropical storms are most +numerous; at others the polar waves; and at others the irregular local +storms, or general tendency to showers. The seasons when the polar waves +are most prevalent, are the most regular, healthy, and productive. Those +where the tropical tendency is greatest, are irregular; and so are those +where the other classes predominate. These differences in the character of +the storms, are but the varying forms in which magnetic action develops +itself. I have said that there was a decided tendency to cirrus without +cumulus, in mid-winter, and cumulus without cirro-stratus or stratus, in +midsummer, and during the intermediate time an intermediate tendency. But +there is a difference between spring and autumn. Dry westerly (not N. W.) +gales prevail in March, and N. E. storms in April and May, but violent S. +E. gales are not as common. On the other hand, the dry westerly gales of +March are comparatively unknown in autumn, and the violent, tropical, +south-easters are then common. + +Snow-storms occur during the northern transit, not unfrequently in April +and May; but they do not occur so near the acme of the northern transit on +its return; nor until it approaches very near its southern limit. The +quiet, warm, and genial air of April, is reproduced in the Indian summer +of autumn, but they present widely different appearances. Those, and many +other peculiarities of the seasons, deserve the attentive consideration of +every one who would become familiar with the weather and its prognostics. + +These irregularities in the character of the seasons have doubtless always +existed, and always been the objects of popular observation. There are +some very old proverbs which show this. I copy a few of the many, which +may be found in Foster's collection. Mr. Graham Hutchison does not seem to +think any of those ancient proverbs worthy of notice. But he misjudges. +They are the result of popular observation, and many of them accord with +the true philosophy of the weather. + +_Irregular_ seasons are unhealthy, and unreliable for productiveness. When +the southern transit was late, or limited, and the autumn ran into winter, +our ancestors feared the consequences in both particulars, and expressed +their fears, and hopes also, in proverbs. Thus, + + "A green winter + Makes a fat churchyard." + +There is very great truth in this proverb. Again, + + "If the grass grows green in Janiveer, + It will grow the worse for it all the year." + +This is emphatically true, for the season which commences irregularly will +be likely to continue to be irregular in other respects. + +Another of the same tenor: + + "If Janiveer Calends be summerly gay, + It will be winterly weather till Calends of May." + +Janiveer is an alteration of the French name for January, and the proverb +is very old. + +So March should be normally dry and windy. + +This, too, they understood, and hence the strong proverb: + + "A bushel of March _dust_ + Is worth a king's ransom." + +And another: + + "March hack ham, + Come in like a lion, go out like a lamb." + +So April and May should be cool and moist. It is their normal condition in +regular, healthy, and productive seasons. The grass and grain require such +conditions; and the spring rains are needed to supply the excessive summer +evaporation. This, too, they well understood. And hence the proverbs: + + "A cold April the barn will fill." + + "A cool May, and a windy, + Makes a full barn and a findy." + +And-- + + "April and May are the keys of the year." + +This was not very favorable, to be sure, for corn; but their consolation +was found, as we find it, in the truth of another proverb: + + "Look at your corn in May, and you'll come sorrowing away; + Look again in June, and you'll come singing in another tune." + +This difference in the character of the seasons occasioned the adoption of +a great variety of "Almanac days;" and they are still very much regarded. +Candlemas-day (2d of February) was one of them. + +Says Hone, in his "Every-Day Book": + + "Bishop Hall, in a sermon, on Candlemas-day, remarks, that 'it has + been (I say not how true) an old note, that hath been wont to be set + on this day, that if it be clear and sunshiny, it portends hard + weather to come; if cloudy and lowering, a mild and gentle season + ensuing.'" + +To the same effect is one of Ray's proverbs: + + "The hind had as lief see + His wife on her bier, + As that Candlemas-day + Should be pleasant and clear." + +St. Paul's day, or the 25th of January, was another great "Almanac day," +and so the verse: + + "If Saint Paul's day be fair and clear, + It does betide a happy year; + But if it chance to snow or rain, + Then will be dear all kinds of grain. + If clouds or mists do dark the sky, + Great store of birds and beasts shall die; + And if the winds do fly aloft, + Then war shall vex the kingdom oft." + +St. Swithin's day was another of these "Almanac days." Gay said truly, + + "Let no such vulgar tales debase thy mind; + Nor Paul, nor Swithin, rule the clouds or wind." + +Yet "_Almanac days_" are still in vogue to a considerable extent--such as +the _three first days_ of the year, old style--the first three of the +season--the last of the season--different days of the month--of the +lunation, etc., etc. And some still look to the breastbone of a goose, in +the fall, to judge, by its whiteness, whether there is to be much snow +during the Winter, etc. + +These _Almanac days should all be abandoned_; they have no foundation in +philosophy or truth. There is one proverb, however, in relation to +Candlemas-day, which the "oldest inhabitant" will remember, and which it +may be well to retain. It has a practical application for the farmer, and +in relation to the length of the winter: + + "Just half of your wood and half of your hay + Should be remaining on Candlemas-day." + +The months, too, have a character which must be remembered and regarded. + +_January_ is the coldest month of the year, in most localities. The +atmospheric machinery reaches its extreme southern transit, for the +season, during the month--usually about the middle. It remains stationary +a while--usually till after the 10th of February. One or more thaws, +resulting from tropical storms, occur during the month, in normal winters, +but they are of brief duration. Boreas follows close upon the retreating +storm with his icy breath. There is a remarkable uniformity in the +progress of the depression of temperature, to the extreme attained in this +month, over the entire hemisphere. It differs in degree according to +latitude and magnetic intensity; but it progresses to that degree, +whatever it may be, with as great uniformity in a southern as northern +latitude. The table, copied from Dr. Forrey, discloses the fact, and so +does the following one, taken from Mr. Blodget's valuable paper, published +in the Patent Office Report for 1853: + + +TABLE SHOWING THE MEAN TEMPERATURE FOR EACH MONTH AT SEVERAL PLACES, VIZ.: + + +---------------------------------------------------------------------+ + | | Lat. | Jan. | Feb. |March.|April.| May. |June. | + |-------------------|-------|------|------|------|------|------|------| + |Quebec, Canada E. |46° 49'| 9.9 | 12.8 | 24.4 | 38.7 | 52.9 | 63.7 | + |New York, N. Y. |40° 42'| 30.2 | 30.8 | 38.5 | 49.1 | 59.6 | 69.1 | + |Albany, N. Y. |42° 39'| 24.5 | 24.3 | 34.8 | 47.7 | 59.8 | 68.0 | + |Rochester, N. Y. |42° 45'| 26.1 | 25.8 | 33.0 | 45.8 | 56.2 | 64.5 | + |Baltimore, Md. |39° 17'| 33.1 | 34.3 | 42.4 | 53.0 | 63.2 | 71.6 | + |Savannah, Ga. |32° 05'| 52.6 | 54.7 | 60.0 | 68.4 | 74.8 | 79.4 | + |Key West, Fla. |24° 33'| 70.0 | 70.7 | 73.8 | 76.3 | 80.2 | 82.1 | + |Mobile, Ala. |30° 40'| 51.3 | 53.7 | 59.4 | 67.1 | 74.1 | 77.8 | + |New Orleans, La. |30° 00'| 54.8 | 54.5 | 61.5 | 67.6 | 74.0 | 78.6 | + |Marietta, Ohio |39° 25'| 32.2 | 34.1 | 42.6 | 53.0 | 61.8 | 69.2 | + |San Antonio, Tex. |29° 25'| 52.7 | 57.9 | 65.5 | 69.7 | 76.4 | 80.5 | + |San Francisco, Cal.|37° 48'| 50.1 | 51.0 | 53.8 | 57.7 | 55.9 | 58.8 | + +---------------------------------------------------------------------+ + + +-----------------------------------------+ + |July. | Aug. | Sept.| Oct. | Nov. | Dec. | + |------|------|------|------|------|------| + | 66.8 | 65.5 | 56.2 | 44.1 | 31.5 | 17.3 | + | 74.9 | 73.3 | 65.9 | 54.3 | 43.5 | 33.9 | + | 72.2 | 70.3 | 61.4 | 49.2 | 39.4 | 28.3 | + | 69.7 | 67.8 | 60.1 | 47.7 | 38.2 | 28.8 | + | 76.6 | 74.5 | 67.7 | 55.8 | 45.0 | 37.8 | + | 81.3 | 80.6 | 76.9 | 67.2 | 58.3 | 52.2 | + | 83.3 | 83.5 | 82.5 | 79.1 | 75.6 | 72.8 | + | 79.8 | 79.4 | 76.1 | 65.7 | 57.0 | 52.8 | + | 80.4 | 79.6 | 77.1 | 69.1 | 57.5 | 56.2 | + | 72.7 | 70.9 | 63.5 | 51.8 | 42.6 | 34.7 | + | 82.3 | 83.3 | 79.9 | 72.2 | 62.2 | 52.1 | + | 57.9 | 62.2 | 61.6 | 61.9 | 56.2 | 50.0 | + +-----------------------------------------+ + +Snows during this month are much heavier, and more frequent, in some +localities than others. The reasons why this is so have been stated. The +mountainous portions of the country receive the heaviest falls. They +affect condensation somewhat, and according to their elevation. They +intercept the flakes before they melt, and retain them longer without +change. The thaws, or tropical storms, also sometimes have a current of +cold air, with snow setting under them on their northern and north-western +border. Such was the case with that investigated by Professor Loomis. +January is without other marked peculiarities. It shows, of course, those +extremes of temperature found, to a greater or less degree, in all the +months, and differs, as the others differ, in different seasons. Normally, +in temperate latitudes, it is a healthy month. The digestive organs have +recovered from that tendency to bilious diseases which characterizes the +summer extreme northern transit, and the tendency to diseases of the +respiratory organs, which characterizes the southern extreme and the +commencement of its return, is not often developed till February. +February, in its normal condition until after the 10th, and about the +middle, is much like January. Often the first ten days of February are the +coldest of the season. The average of the month is a trifle higher, in +most localities, as the tables show. This results from the increasing +warmth of the latter part of the month. There are localities, however, +where the entire month is as cold as January. Such (as will appear from +Blodget's table) are Albany and Rochester, in the State of New York, and +New Orleans, in Louisiana. At most places the difference is slight, either +way. South of the latitude of 40° heavy snows are more likely to occur in +the last half of January and first half of February than earlier. About +the middle of the month we may expect thaws of more permanence in normal +seasons. They are followed, as in January, by N. W. wind and cold weather, +but it is not usually as severe. Many years since, an observing old man +said to me, "_Winter's back breaks about the middle of February_." And I +have observed that there is usually a yielding of the extreme weather +about that period. Here, again, it is interesting and instructive to look +at the tables, and see how regularly and uniformly the temperature rises +in all latitudes, at the same time; as early and as rapidly at Quebec as +at New Orleans or San Antonio; and subsequently rises with greatest +rapidity where the descent was greatest. The elevation of temperature does +not progress northwardly, a wave of heat accompanying the sun, but is a +magneto-electric change, commencing about the same time over the whole +country, and indeed over the hemisphere. + +March is a peculiar month--the month of what is termed, and aptly termed, +"unsettled weather." It, may "come in like a lion," or be variable at the +outset. The northern transit is fairly started, and is progressing +rapidly, and there is great magnetic irritability. A reference to the +table of Dr. Lamont will show that the declination has increased with +great rapidity. Normally, the early part is like the latter part of +February, and the latter part approaches the milder but still changeable +weather of April. Its distinguishing feature is violent westerly wind. Not +the regular N. W. only--although that is prevalent--but a peculiar +westerly wind, ranging from W. by N. to N. W. by W., often blowing with +hurricane violence. This wind was alluded to on page 130. With the change +and active transit to the north, in February and in March, comes the +tendency to diseases of the respiratory organs--pneumonias and lung +fevers--and this is the most dangerous period of the year for aged people. + +April is a milder and more agreeable month. During some period of it, in +normal seasons, and at other times in March, there is a warm, quiet, +genial, "lamb-"like _spell_, exceedingly favorable for oat seeding. When +it comes, advantage should be taken of it, for long heavy N. E. storms are +liable to occur, and frequently with snow. On the latitude of 41° heavy +snow-storms are not uncommon in April. Within the last fifteen years two +such have occurred after the 10th of the month. April, as we have seen, +should be cool and moist. If dry, the early crops are endangered by a +spring drouth; if very wet, there is danger of an extreme northern +transit, and an early summer drouth. It is emphatically true that + + "April and May are the keys of the year." + +Its distinguishing peculiar feature is the gentle, _warm_, _trade_ +rains--"_April showers_"--which, in the absence of great magnetic +irritability, that current drops upon us. There is great _mean_ magnetic +activity, but it is not so _irregularly excessive_ as in March. + +May, in our climate, should be, and normally is, a wet month, and a cool +one, considering the altitude of the sun. The atmospheric machinery which +the sun moves is, however, ordinarily about six weeks behind it--the +latter reaching the tropic the 20th of June, and the former its farthest +northern extension about six weeks later. Hence it is not a cause for +alarm if May be wet and cool. The great staples, wheat, grass, and oats, +are benefited; and corn, according to the proverb, will not be seriously +retarded. The movable belt of excessive magneto-electric action, with its +tropical electric rains, so exciting to vegetation, and its periods or +terms of excessive heat, is on its way north, and sure to arrive in +season, and remain long enough to mature the corn. There have been but two +seasons in this century when corn did not mature in the latitude of 41°. +One during the cold decade, and the cold part of it, between 1815 and +1820; and the other, during the cold half of the fourth decade, between +1835 and 1840. + +The distinguishing feature, if there be one, of May, is its long, and, for +the season, cool storms. These have, in different localities, different +names. In pastoral sections we hear of the "_sheep storms_"--those which +effect the sheep severely when newly shorn--killing them or reducing them +in flesh by their coldness and severity. + +In relation to this too early shearing, there is an old English proverb, +in "Forster's Collection," viz.: + + "Shear your sheep in May, + And you will shear them all away." + +So there are others called "_Quaker storms_," which occur about the time +when that estimable sect hold their yearly meeting. And there are other +names given in different localities to these long spring storms. But they +are all _mere coincidences_--equinoctial and all. + +Notwithstanding the storms, however, the temperature rises at a mean. The +declination is often as great as in mid-summer. The earth is growing +warmer by the increase of magneto-electric action, whatever the state of +the atmosphere. The yellow, sickly blade of corn is extending its roots +and preparing to "_jump_" when the atmosphere becomes hot, as it is sure +to do, when the machinery attains a sufficient altitude, how backward +soever it may seem to be. The farmer need not mourn over its backwardness, +unless the season is a very extraordinary one, like those of 1816 and +1836. The storms ensure his hay, wheat, and oat crops; the warming earth +is at work with the roots of his corn, and is filling with water, and +preparing for the hot and rapidly-evaporating suns of mid-summer. The +earth would grow warmer if every day was cloudy. + +By the middle of June the atmospheric machinery approaches its northern +acme, the summer sets in, and not unfrequently, as extremely hot days +occur during the latter part of the month, as at any period of the +summer. But the heat is not so continuous, or great, at a mean. + +From the middle of June to the latter part of August is summer in our +climate, and during that period from one to three or four terms of extreme +heat occur, continuing from one to five or six days, and possibly more, +terminating finally in a belt of showers overlaid with more or less +cirro-stratus condensation in the trade, and controlled by the S. E. polar +wave of magnetism, and followed by a cool but gentle northerly wind. +During these "heated terms," a general showery disposition sometimes, +though rarely, appears, with isolated showers, which bring no mitigation +of the heat. Not until a southern extension of them appears, followed by a +N. W. air, does the term change, so far as I have observed. + +By the 20th of August, in the latitude of 42°, an evident change of +transit is observable, by one who watches closely, although the range of +the thermometer in the day-time may not disclose it. A greater tendency to +cirrus-formation is visible. The nights grow cooler in proportion to the +days. The swallows are departing, or have departed; the blackbirds, too, +and the boblinks, with their winter jackets on, _their plumage all changed +to the same colors_, are flocking for the same purpose, and hurrying away. +The pigeons begin to appear in flocks from the north, and the first of the +blue-winged teal and black duck are seen straggling down the rivers. At +this season, and nearly coincident with the change, the peculiar annual +catarrhs return. These are colds (so called) which at some period of the +person's life were taken about or soon after the period of change, and +have returned every year, at, or near the same period. They soon become +_habitual_, and no care or precaution will prevent them. I know one +gentleman who has had this annual cold in August for twenty-seven years, +with entire regularity; and another who has had it nineteen years; and +many others for shorter periods. I never knew one which had recurred for +two or three years that could be afterward prevented, or broken up. _Very +instructive are these annual catarrhs_ to those who think health worth +preserving, and in relation to the change of transit. + +_The change is felt over the entire hemisphere._ Between the 20th of +August and the 10th of September hurricanes originate in the tropics and +pursue their curving and recurving way up over us; or long "north-easters" +commence in the interior and pass off to E. N. E. on to the Atlantic, +followed now in a more marked degree by the peculiar N. W. wind, so common +over the entire Continent in autumn and winter. + +By the 10th of September the pigeons may be seen in flocks in the morning, +and just prior to the setting in of a brisk N. W. wind, hurrying away +southward with a sagacity that we scarcely appreciate, to avoid the +anticipated rigors of winter, and to be followed soon by all the migratory +feathered tribes that remain. + +The nights grow cooler, although the sun shines hot in the day-time, and +woe to the person, unless with an iron constitution, who disregards the +change, and exposes himself or herself without additional protection, to +its influence. Nature has taken care of those who depend upon her, or upon +instinct, for protection. The feathers of birds and water-fowl are full; +the hair and the fur are grown. Beasts and birds have been preparing for +the change, and are ready when it begins. They know that the earth is +changing. The shifting machinery is fast carrying south that excess of +negative electricity which has so much to do with giving it its summer +heat. They feel its absence, even during the day, and the contrast between +that and the positively electrified northern atmosphere, which now follows +every retreating wave of condensation. + +The musk-rat builds, of long grass and weeds, his floating nest in the +pond, that he may have a place to retire to, when the rain fills it up and +drives him from his burrow in its banks. + +But man, with all his intellect, is too heedless of the change. Additional +clothing is now as necessary to him as to animals, but it is burdensome to +him in the day time, and therefore he will not wear it, how much soever it +would add to his comfort and safety during the night. He stands with his +thin summer soles upon the changed ground, or sits in a current, or in the +night air, less protected than the animals, and dysentery or fever sends +him to his long home. He has _intelligence_, but he lacks _instinct_. He +has time for the changes of dress which fashion may require, but none for +those which atmospherical changes demand. _Fashion_ has attention in +_advance_; _death_ none till _at the door_. + +Now the southern line of the extra-tropical belt of rains descends upon +those who, living between the areas of magnetic intensity, have a dry +season; and the focus of precipitation in that belt descends every where. +"_Winter no come till swamps full_," the Indians told our fathers, and +there is truth in the remark; although like other general truths +respecting the weather, it is not always so in our climate. Rains fall +during the autumnal months, as during the spring months, and while the +transit of the machinery is active and the evaporation is less. And the +magnetic comparative rest, and the seed time and equable "spell" of April +is reproduced in the Indian summer of autumn. + +The machinery gradually and irresistibly descends, and with an excess of +polar positive electricity, comes snow; Boreas controls, and winter sets +in, reaching its maximum of cold in January again. + +Remembering, then, the differences in the normal conditions of the seasons +and months, and the different characters that the winds, and storms, and +clouds, and other phenomena bear in them respectively, let us now look at +the signs of foul or fair weather not herein before fully stated, upon +which practical reliance may be placed. + +In the first place, we must look to the forming condensation. There are +many days when the atmosphere is without visible clouds, but few when it +is entirely without condensation. Such days are seen during the dry season +in the trade-wind region; and with us, in mid-summer drouths, which +partake of this tropical character; and when, at any season, but +particularly in winter, the N. W. wind in large volume has elevated the +trade very high. Condensation is not necessarily in form of visible cloud. +It may be of that smoky character which sometimes attends mid-summer +drouths, giving the sun a blood-red appearance; or it may be like that +change from deep azure to a "lighter hue," obscuring the vision, which +Humboldt describes as preceding the arrival of the inter-tropical belt of +rains. Gay-Lussac, and other aeronauts, have seen a thin cloud stratum at +the height of 20,000 to 30,000 feet, not visible at the earth, although +some degree of mistiness and obscurity were observed. At that elevation +the clouds are thin, and always white and positive. Some degree of +turbidness is frequent; it may occur, as we have stated, with N. W. wind, +but, if it does, the wind soon changes round to the southward. + +This turbidness or mistiness, where it exists, and indicates rain, does +not disappear toward night, as it should do if but the daily cloudiness +which results from ordinary diurnal magnetic activity, but becomes more +obvious at nightfall; and, when hardly visible at mid-day, or during the +afternoon, may then be observed, obscuring in a degree, the sun's rays; +and, later in the evening, forming a circle round the moon. Thus Jenner-- + + "Last night the sun went _pale to_ bed, + The moon in _halos_ hid her head." + +And so, too, Virgil-- + + "The sun, too, rising, and at that still hour, + When sinks his tranquil beauty in the main, + Will give thee tokens; certain tokens all, + Both those that morning brings, and balmy eve. + + * * * * * + + When Sol departs, his mighty day-task done, + How varied hues oft wander on his brow. + + * * * * * + + If the ruddy blaze + Be _dimm'd_ with _spots_, then all will wildly rage + With squalls and driving showers: on that fell night + None shall persuade me on the deep to urge + My perilous course, or quit the sheltering pier. + But if, when day returns, or when retires, + _Bright_ is the orb, then fear no coming rain: + Clear northern airs will fan the quiv'ring grove. + Lastly, the sun will teach th' observant eye + What vesper's hour shall bring; what clearing wind + Shall waft the clouds slow floating--what the South + Broods in his humid breast. Who dare belie + The constant sun?" + +More frequently this kind of condensation is sufficiently dense at +night-fall to take shape, and show a bank when the sun shines horizontally +through a mass of it. I am now speaking of _storm_ condensation, or that +which indicates the approach of a storm. Thunder clouds at nightfall, +dark, dense, and isolated, are, of course, to be distinguished. Those, +every one understands to indicate a shower, and immediate succeeding fair +weather. + +The halos do not, in cases of incipient storm condensation, always appear. +The moon may not be present: though, in her absence, I have seen them in +the light of the primary planets; or she may be in the eastern portion of +the heavens. When this is so, and the condensation forms slowly, there may +be less appearance of it, after the sun disappears, than before, although +a storm is approaching, and sure to be on by the middle of next day, and +perhaps with great violence. When the failure of the light no longer +reveals the denser condensation in the west, the stars may shine, as did +the sun, dimly but visibly, through the partial and invisible +condensation; and one who did not notice the bank in the west, at +nightfall and before dark, may be deceived by the seeming clearness of the +evening. Thus Virgil-- + + "Mark, with attentive eye, the rapid sun-- + The varying moon that rolls its monthly round; + So shalt thou count, not vainly, on the morn; + _So the bland aspect of the tranquil night + Will ne'er beguile thee with insidious calm_." + +All early condensation and indications derived from it, must be looked for +in the west. From that quarter all storms come. These indications at +nightfall are of a varied character. They may consist of primary +condensation in the trade, or of secondary condensation, scud running +north toward a storm, the condensation of which has not yet visibly +reached us, but which will extend south and pass over us. It may be a +heavy bank, or consist of narrow cirrus bands. Cirro-stratus cloud banks, +in the S. W., in the fall and winter, of a foggy and uniform character, +are indicative of snow. The body of the storm will pass south of us, and a +portion over us, the wind be north of east, and the snow will not be +likely to turn to rain before it reaches the earth, by reason of a +southern middle current. + +Banks in the N. W. indicate rain at all seasons. The storm is north of us, +working southerly, and such storms rain on the southern border--in winter +even--because they have the wind on that border from south of east. It +may, indeed, snow, but if so, probably in large flakes, soon turning to +rain. There are other appearances at nightfall which deserve +consideration. A red sun, with smoky air, is indicative of continued dry +weather, a frequent appearance in dry terms, lasting three or four days, +at least, from the commencement. So is a red appearance of the sky, when +there are no clouds, indicative of a fair day following. On this subject +we have an allusion to the weather, by our Saviour while on earth, which, +like all such allusions found in the Bible, is of remarkable philosophical +accuracy. It is found in Matthew, chapter xvi., verses 2 and 3: "He +answered and said unto them, When it is evening ye say, It will be fair +weather, for the sky is red. And in the morning, It will be foul weather +to-day, for the sky is red and lowering. O, ye hypocrites, ye _can +discern_ the face of the sky," etc. + +Another allusion to the weather, though not applicable to this point, I +will refer to in passing. It is found in Luke, chapter xii., verses 54 and +55: "And he said also to the people, When ye see a cloud rise out of the +west straightway ye say, There cometh a shower; and so it is. And when ye +see the south wind blow, ye say, There will be heat; and it cometh to +pass." + +This is all very true, and might have been cited to show the universality +of the phenomena. But to return. + +We have an old English proverb alluding to the same phenomena, of great +value and truth, viz.: + + "An evening red and a morning gray + Are sure signs of a fair day; + Be the evening gray and the morning red, + Put on your hat or you'll wet your head." + +The sky is red if there be no condensation at the west to obscure the rays +of the sun; if there be, it is gray, or there is a bank or cloud, and it +is obscured. So if there be no condensation over, or to the east of us, in +the morning, to reflect the rays of the sun, the sky is gray; if there be +such condensation, the sun is reflected from it, and the sky is red. Such +morning condensation is indicative of foul weather. It is, as we have +said, the eastern edge of an approaching storm, on, or under which, the +sun shines and illumines it. Thus, at night, it shines through a portion +at the west, which is situate between the sun and us, making the sky gray: +but shines on, or under, a portion in the morning, east of us, but not far +enough east to obscure the horizon, and the rays of the rising sun are +reflected from it. In either case the red or gray appearance results from +the relative situation of the sun and the eastern edge of an approaching +storm. + +The following couplet of Darwin is an apt description of the morning +appearance: + + "In fiery red the sun doth rise, + Then wades through clouds to mount the skies." + +The sun is often reflected in vivid colors, from the under surface of +clouds, at sunset. This is an indication of fair weather. It is evident +the sun shines through a _clear atmosphere beyond the cloud_, or his rays +would not reach and illume the lower surface of the cirro-stratus with +such distinctness. He "_sets clear_," as is said; the clouds are passing +off, and there are none beyond. It is this appearance, in different forms, +when there happen to be patches of broken, melting cirro-stratus above the +horizon, which makes the beautiful sunsets that attract attention. So the +sun is reflected, in beautiful colors sometimes, from the cumulus clouds +which have passed over to the east. The most beautiful and variegated I +have ever seen, were reflected from that imperfect cumulus condensation +which takes place occasionally during long drouths--doubtless resembling +that which is seen over Peru, hereinbefore alluded to, as described by +Stewart. + +It is not, then, the presence of cloud condensation at the west, at +nightfall, which alone indicates foul weather; but such condensation, +whatever its form, as evinces that it is not the _dissolving_ cloud of the +day, but the eastern, approaching portion of a _still denser portion +beyond, through, or under which, the sun can not shine clearly, but which +wholly or partially obscures it_. _Remembering this philosophy of the +matter_, the observer will soon be able to detect the various forms of +condensation which originate or exhibit themselves at nightfall, and +whether they indicate an approaching storm or not, without a more explicit +specification of them. It is an important hour for observation; "Let not +the sun go down" without attention. + +When the condensation is obvious, but thin, at nightfall, it may not, as I +have said, be discernible in the evening. But there are methods by which +the incipient storm condensation may be detected. The number of the stars +visible, and the _distinctness_ with which they may be seen, indicate the +absence or presence of condensation and its density. Virgil, alluding to +the indications of fair weather, says: + + "_Brightly_ the stars shine forth; Cynthia no more + _Glimmers_ obnoxious to her brother's rays; + Nor fleecy clouds float lightly through the sky." + +The brightness of the stars and the clear appearance of the moon show the +absence of condensation and the _dissolution_ of the fleecy clouds at the +close of the day is, as we have seen, always a fair-weather indication. + +There is much true philosophy in the allusions of Virgil to the moon. +Thus-- + + "When Luna first her scatter'd fires recalls, + If with _blunt horns_ she holds the _dusky_ air, + Seamen and swains predict th' abundant shower." + +The horns, or angles of the moon will, of course, appear distinct and +sharp or indistinct and blunt, in proportion to the amount of +condensation in the atmosphere which impedes the passage of the light. For +the same reason, when the moon is new, her entire disk is visible when the +atmosphere is very clear, by reason, as is supposed, of light reflected +from the earth to the moon and back to us. This double reflection can only +take place when the atmosphere is very clear. Hence, Virgil alludes to it, +and correctly, as an indication of continued fair weather: + + "If (mark the ominous hour!) + The clear fourth night her lucid disk define, + That day, and all that thence successive spring, + E'en to the finished month, are calm and dry." + +Probably Virgil alluded to a month of the summer trade-wind drouth which +reaches up on Southern Italy. But that appearance of the moon is +occasionally seen here, and the indication is, in degree, philosophically +true. + +It is somewhat more difficult to determine what will be the result of the +condensation seen at the west in the morning, and which is not so far +east, or of such a character, as to reflect the rays of the sun; for, +although always suspicious, it is sometimes of a foggy character, and +disappears between eight and nine o'clock. If it increases in density +after ten o'clock, or is of a dense cirro-stratus character, rain may +generally be expected. If of a decided _cirro-cumulus_ character, it is +certain to disappear. Cirro-cumulus is seen in small patches, with small, +distinct, and rounded masses, in summer, in the morning, and sometime, +during the day, after high fog has disappeared, and at other times, and is +always, when of that _distinct_ character, a fair weather indication. I +have seen it thus when the wind was blowing from the N. E., and the scud +running toward a storm passing near, but to the south of us, when those +who relied upon the existence of the wind and scud as evidences that we +were to have the desired rain, were deceived. Thus, the couplet from an +old almanac: + + "If _woolly fleeces_ strew the heavenly way, + Be sure no rain disturb the summer day." + +When this morning condensation is not high fog, and is dense and passing +east with a wavy appearance, it is very certain to rain. Jenner says: + + "The boding shepherd heaves a sigh, + _For see, a rainbow spans the sky_." + +An old almanac had the following verse: + + "A rainbow in the morning + Is the shepherd's warning; + A rainbow at night + Is the shepherd's delight." + +So the proverb was originally made; but as our ancestors were not +shepherds, and had a horror of ocean storms, it was commonly quoted, in +this country, in the following form: + + "A rainbow in the morning, + The sailors take warning," etc. + +Rainbows are not reflected from _clouds_, but falling rain, and a morning +rainbow at the west is, of course, evidence that it is _actually raining +there_, and will, in all probability, pass over us. "Thunder in the +morning, rain before night," is a common saying, and a true one. There is +a belt of showers, or showery period approaching, of unusual +intensity--for thunder showers in the morning are rare. The afternoon is +their most common period, and they are very apt to appear then, when the +morning is showery. + +Of the different forms of cirrus and cirro-stratus, which appear during +the day, and indicate approaching storms, or of cumulus indicative of +showers, it is difficult to give an intelligible description without very +many illustrations. I have many daguerreotype views, taken at different +seasons of the year, and at a time when different forms of cirrus and +cirro-stratus condensation, indicative of storms, exhibited themselves. +They differ, as I have said, and it must be remembered, very much at +_different seasons_ of the year, and in _different years_, and their +delicate shades are taken with difficulty by the artist, and reproduced +with difficulty, and only at considerable expense, by the engraver; and I +have omitted them. The time will come when a knowledge of their language +will be sought for and read--when the "countenance of the sky" will be an +object of intelligent interest to all whose business may be affected by +the weather, or who love to learn of nature. But it is not yet. This is +the age of theory and speculation. The time of actual, practical, +connected observation and prognostication, which may justify expensive +illustration, is yet to arrive. + +The reader will find in the general plates representations of several +kinds of cirri. They are delicate, always white, more or less fibrous, and +form in the upper part of the trade or the adjoining atmosphere above it. +Their character and elevation should be studied, and the observer should +be careful to distinguish which is the most elevated. Not unfrequently it +may seem, to a hasty observer, that the cirrus is below the cirro-stratus +or forming stratus. But the genuine cirrus never is. It forms near, and +above, the point of congelation, and is often composed of crystals of ice +or snow. If they fall, they melt and evaporate, when there is no storm, +before reaching the earth. Aeronauts have met with them and their crystals +when there was no fall of moisture at the surface of the earth; and the +angles of reflection exhibited by halos and other optical phenomena which +form in them, enable us to detect their crystallization and the form of +it. + +They are produced by electric changes which condense the vapor, and the +coldness of the air at that elevation freezes it at the _instant of its +condensation_. + +Congelation is crystallization, and all crystallization is electric, or +magneto-electric. The snow-flakes differ in form and size according to the +suddenness of the condensation, the amount of moisture condensed, the +polarity of the strata through which they pass, and their consequent +attraction and adhesion to each other. + +The connection of electricity with these formations of cirri has +frequently been admitted, and it is perfectly obvious that the long +fibrous bands, shooting from horizon to horizon, could not be formed by +commingling of currents any more than the perfectly isolated, distinct, +enlarging-outward cumulus hail-storm, could be so formed. Cirri form at +the line of meeting, between the trade and the upper atmosphere, and in +one or the other, or both, very much according to the season, and the +suddenness with which storms are produced. These often _induce_ a layer of +cirro-stratus or stratus at the lower line of the counter-trade, and in +the surface-atmosphere, which precipitates; and this operation is clearly +discernible, and very frequently, before gentle rains. Condensation in the +whole body of the trade is usually in the form of turbidness or mistiness, +a bank or incipient stratus, without cirri. + +It seems matter of astonishment that water should float so far condensed, +in strata where the air is so much lighter, without being precipitated. +But electric attraction and repulsion between the different strata and the +vesicles, explain it. + +In mid-winter, the cirrus forms are prevalent and most distinct. After +severe cold weather, when a storm approaches, the cirri form in long, +narrow threads, parallel to each other, extending from about W. S. W. to +E. N. E., gradually thickening and forming, or inducing, cirro-stratus and +stratus, and dropping snow. This form is called the _linear_-cirrus. The +tufted, and other fibrous forms, are seen in patches also, in great +distinctness, during these mid-winter days, when the wind gets around to +the southward, and the weather is pleasant. Such days are called +"_weather-breeders_," and their _offspring_ the patches of cirrus, which +are to extend and compose, or induce the storm, and indeed are an advance +part of it, are then never absent. A clear, moderate day, in a normal +winter, with wind from any southern point, however light, between the 1st +of January and the middle of February, without these patches of cirrus, is +very uncommon. Watch and see whether they tend to cirro-stratus, or +whether the wind gets around to the N. W. at nightfall, and they +disappear. If the former, a storm may be expected; if the latter, fair +weather. + +Thus there are three peculiarities attending the forming cirrus of +mid-winter (1st of January to 10th of February): long, fibrous, parallel +bands in the morning (linear cirrus), gradually coalescing as the day +advances, after severe cold; the comoid, curled, or tufted cirrus, in +curling bunches, called "_mares'-tails_," and the _transverse_, when the +fibers are in bands or threads, which are not parallel, but cross each +other at angles, more or less acute. The two former varieties are +represented on Figure 5, page 26, indicated by one bird, but the last form +is a very prevalent one in our atmosphere. + +Various names have been given to different forms of _cirro-stratus_. Those +represented in Figure 5, page 26, are the "_cymoid_" on the right, the +"_mottled_" on the left, below the cirro-cumulus; and the "_linear_" +below that. The form known as the "_mackerel sky_" is not represented +there. It consists of regular forms, resembling the _waves_ on the surface +of the water when the wind blows a gentle breeze. But the _wavy_ form, and +of all sizes, is very frequently assumed by cirro-stratus, which is +rapidly condensing, and turning to stratus. In the "mackerel sky," +strictly so called, the waves are small, parallel, nearly distinct and +equi-distant, and resembling the appearance of a school of mackerel, +swimming in the same direction, one above another. All _wavy_ forms of +cirro-stratus indicate a disposition to increased condensation and rain. +When the waves are very large and dense, and cross obliquely, or unite at +one end, rain is very certain to fall soon, if the line of progress of the +condensation is over the observer, and the clouds are seen in the western +or N. W. quarter of the sky. + +But there are few forms which are not occasionally seen when no rain or +snow falls. The intensity of the electric action which produces them may +not be sufficient to effect precipitation, or they may be the attendant, +attenuated _lateral_ condensation, which frequently "thins out" a +considerable distance from the dense, precipitating portions of the storm. + +If that denser portion is north of us, the probabilities of rain are +greater, for there is always a probability that the storm may be of the +character which is extended south, by a polar wave. The observer must +watch the formation of cirri, and the different forms of cirro-stratus and +stratus, and become familiar with their appearance. It is not a difficult +task. With the aid of a few general directions he will soon be familiar +with them: + +1. Get a correct idea of the different characters of the primary clouds. +The true fibrous _cirrus_--the different forms of _cirro-stratus_--the +smooth, uniform _stratus_--the _cirro-cumulus_, which is nothing but a +cirro-stratus, separated into _distinct masses_ by the repulsion of static +electricity--and the _cumulus_, too distinct ever to be mistaken. There is +no difficulty, except with the varied forms of cirro-stratus. It is +useless to attempt to give, or the observer to rely on, names for these +numerous forms, without as numerous illustrations. Those in use are rarely +applied correctly. I have never met with ten persons who applied even the +term "mackerel sky" to the same precise form of cirro-stratus. In relation +to all of them it is to be observed that polar belts of condensation, and +local appearances of considerable extent, are often too feeble in action +to precipitate, even when the mackerel form is present; and all may be the +lateral attendants of passing storms. Therefore, + +2. Satisfy yourself whether the cirrus or cirro-stratus increases in +density and tends to the formation, or induction, of stratus; and whether +it is isolated, or an extension of the condensation of a storm, and if the +latter, _where that storm is_. The time will come when an intelligent use +of the telegraph will do this for you. + +3. Look also to the character of the wind, if there be any. On this +subject I have perhaps said all that is necessary in the preceding pages. +Next to condensation, the direction and character of the wind is the most +valuable prognostic. Indeed it often tells us that a storm is approaching, +and the quarter from which it will come, and its character, before the +condensation is visible. + +4. See if there is any _secondary_ condensation or scud. These are +sometimes seen running toward a storm, when there are not distinct clouds +visible in the western horizon, at nightfall, or in the evening, as in the +instance stated in the introduction, and sometimes from the north-east, as +in cases heretofore so often stated. But the easterly scud do not often +form in winter, until after the cirrus has passed into the form of +cirro-stratus, or has induced the latter forms in the inferior portion of +the trade, or the surface atmosphere. + +The inductive effect of the primary condensation, therefore, is not +always, and especially in winter, sufficient to create the easterly +current and scud, and it is often the case that the easterly wind is not +felt, or the scud seen, in snow-storms, until the snow has begun to fall, +and the first snow will fall with a S. W. air, as I have heretofore +stated. But when the condensation has so far advanced toward stratus that +the easterly wind and scud are obvious, there is little or no doubt that +rain or snow will fall speedily. The occasional occurrence of easterly +wind and scud, without rain, however--dry north-easters, as I have termed +them--in connection with storms passing south of us, or condensation too +feeble to precipitate, should be remembered. The long, dry, +north-easterly winds of spring have been attributed to the icebergs, but +they are overlaid by feeble stratus or cirro-stratus condensation, or are +the result of attraction, by a more southern precipitation. The observer +must be careful to distinguish between the various forms of N. W. scud and +cirro-stratus, which they sometimes resemble. This he may do _from the +direction in which they move_. Cirro-stratus always moves from some point +between S. S. W. and W. S. W. to some point between N. N. E. and E. N. E. +The various forms of N. W. scud move to the S. E. The March, foggy scud, +from between W. and N. W., rarely have any cirro-stratus above them, but +rather a peculiar turbid condensation. + +The character of the primary condensation, the direction and force of the +wind, and the direction of the secondary condensation or scud, must be the +main reliance of the observer. But I must reiterate that they all differ +in different kinds of storms, in different seasons of the same year, and +the same seasons of different years; and the observer must be careful to +make due allowance for those differences. + +There are, however, divers other secondary signs, which, although not +alone to be relied upon, will aid the observer, if carefully studied, when +the character of the clouds, and the pressure of easterly or southerly +wind and scud, are not decisive. Of these, a large class are electrical. + +The smoke descends the adjoining chimney-flues, or outside of the chimney, +toward the ground. + +Thus, Darwin, as quoted by Hone: + + "The smoke from chimneys right ascends, + Then, _spreading_, back to earth it bends." + +Smoke is electrified _positively_, by the act of combustion; the earth and +the adjacent atmosphere, when storms are gathering or approaching, is +_negative_. Hence the smoke spreads, and is attracted downward by an +opposite electricity. On the other hand, it is interesting to see, at +other times, and when the difference in temperature is not material, but +the whole atmosphere is positive, with what rapidity and compactness the +smoke will ascend in a _straight and elevated column_ from the chimney, +repelled by a similar electricity. I am aware it is generally supposed the +smoke descends because the _air is lighter_. But it is a mistake. I have +seen it descend when the barometer was at 30°.60, or .60 above the mean. + +There is, too, a draught downward in chimneys, in such cases when there is +no smoke or fire in any of its flues. Thus Jenner says: "The soot falls +down;" whether he meant by this that there was an actual fall of soot +other than what is occasioned by the rain falling in through the chimney +top, and disturbing the soot, as sometimes happens, I do not know. It +occurs rarely, and is of very little practical importance. But every +housewife knows that chimneys, which have been used in winter, and are +full of soot, _smell_ before storms. The odor results from a downward +draught and the dampness of the air. So the smoke from one flue will +descend another, into some unused room, on such occasions. Another class +of these electrical signs are felt by those who are suffering from chronic +diseases, which have affected the nerves and made them sensitive. Thus +Jenner: + + "Old Betty's joints are on the rack." + +And Hone adds: + + "Her corns with shooting pains torment her, + And to her bed untimely send her." + +But Old Betty's rheumatism or corns are not alone in this. Those whose +bones have been broken feel it. All invalids feel it. And, indeed, all +observing healthy persons may, and do, although all are not distinctly +conscious of it. It is common for such to say, I feel sleepy, or I feel +dull, or, It _feels_ like snow, or _feels_ like rain, and thus from their +own feelings to be able to predict, not only falling weather, but its +_character_, whether snow or rain, at a time when either may occur +consistently with appearances. + +This change is a change from the positive electricity which is so +congenial to the active--"bracing" is the usual term--to negative and +damp--for this change is accompanied by condensation, as I believe all +changes from positive to negative are. Certain it is, if the atmosphere is +highly charged with negative electricity, condensation takes place; if +with positive, evaporation. Perhaps it is a change of the associated +electricity which accompanies magnetism, and not of the free atmospheric +electricity alone. Hence another phenomenon alluded to by Jenner: + + "The walls are damp, the ditches smell." + +There are localities where this dampness is very obvious. The celebrated +William Cobbett, many years since, when a farmer on Long Island, observed +and published the fact that the stones grew damp before a storm. I know of +flagging stones that usually grow damp two or three hours before rain, +especially in spring and fall, and every step taken upon them is made +visible by a corresponding increase of condensation. + +The reverse of this takes place just before the close of storms. Flagging +stones, and walls under cover, will frequently become dry before the rain +ceases. The negative electricity becomes less as the positive prevails, +although the clouds above are still dropping rain. + +In the comparatively moist, showery climate of England, these changes from +positive to negative alternate rapidly between successive showers; but +observations of electric phenomena, or of clouds, in that climate, are +not, without qualification, safe guides for us. + +So "the ditches smell," particularly in the evening before a rain, when +the immediate surface-atmosphere is charged with negative electricity, and +the _condensing moisture_ prevents the diffusion of the odors. For the +same reason the candle will not relight, and there is crackling in the +ashes or lamp. Thus, again, Virgil: + + "Maidens that nightly toil the tangled fleece + Divine the coming tempest; in the lamp + _Crackles_ the oil, the gathering wick grows dim." + +Virgil did not live in our cold climate, and knew nothing of the crackling +in the fire, or in the ashes or coals which remain after the wood is +consumed. The lamp exhibits it on a smaller scale, and perhaps he had +noticed it when in company with the maidens. But it is sometimes +noticeable even in the lamp or candle with us. A small particle of +moisture will produce it, in a marked degree, at any time. + +In winter, when the air is highly positive and cold, the candle can be +blown out, and by another puff of the breath relighted, with ease. But +when the electricity before a storm becomes negative, and partial +condensation takes place, this can not be done. This partial condensation +before storms and showers shows itself upon vessels containing cold-water, +in summer. It seems to be the received opinion, that the condensation is +evidence of a greater _quantity_ of moisture in the atmosphere. But this, +too, is a mistake, and hence the little reliance to be placed on +hygrometers. + +This partial condensation is sometimes visible. When the sun shines +clearly, at the east or west, through a _small opening_ in the clouds, the +condensing vapor is shown by the streaks of sunlight, just as the fine +particles of dust are seen in a dark room, when a few rays of sunlight are +admitted through a small aperture. This phenomenon is often observed, and +it is said of it--"It's a going to rain; _the sun is drawing water_." + +Virgil alludes to this as seen in the east in the morning, thus: + + "But when beneath the dawn _red-fingered rays_ + Through the dense band of clouds _diverging_ break, + + * * * * * + + Ill does the leaf defend the mellowing grape; + Leaps on the noisy roof the plenteous hail, + Fearfully crackling." + +It is well ascertained that storm-clouds of great intensity have polarity +in the different portions, and that in the less intense magneto-electrical +climate of England isolated showers are often of this character--the +polarity existing in rings. Showers are doubtless thus found with us. Mr. +Wise got into one of them; see his description (Theory and Practice of +Aeronautics page 240). + +I have, in another place, alluded to the upward attraction of the dust +beneath the advance condensation of a shower. Jenner alludes to it in the +following lines: + + "The whirling winds the _dust_ obeys, + And in the rapid eddy plays." + +So Virgil: + + "Light chaff and leaflets, _flitting, fill the air_, + And sportive feathers circle on the lake." + +All these are electrical. + +In England, where the action of such isolated clouds is less intense, the +different electricities in different portions of the cloud, whose opposite +and changing action produce all the phenomena, the condensation, the cold +and congelation, the currents, etc., have been accurately ascertained. We +can not get into the situation occupied by Mr. Wise. But every man may +observe these _intestine motions_ occasionally, in the advance +condensation of an isolated thunder-shower, in front of, but near the +smooth line of falling rain. They are more lateral than upward or +downward, and are often exceedingly rapid in movement. + +I have said that hail has often been found to fall from particular and +well-defined portions of a cloud, and rain from the other portions, the +hail being positive, and rain negative. An instance of very striking +character may be found in Espy's Philosophy of Storms (Introduction, page +xx.) Doubtless in all cases thunder-showers, which are isolated and +distinct, have opposite electricity in different portions, to whose active +agency all the phenomena are owing. And the return of electricity to the +earth in the rain explains the greater fertilizing effect of the latter +compared With all artificial watering. He was a true philosopher who +attempted to stimulate vegetation by electricity. + +Sounds may sometimes aid the observer in doubtful cases in foretelling the +weather. The roar of the surf, or breaking of the waves on the shore, when +great bodies of water are disturbed by a precedent storm-wind, often heard +before the wind is perceived on the land, I have already alluded to. And +thus Virgil: + + "When storms are brooding--in the _leeward gulf_ + Dash the swelled waves; the mighty mountains pour + A harsh, dull murmur; far along the beach + Rolls the deep rushing roar." + +The moaning or whistling of the wind all have noticed. It is not uncommon +to hear the expression, "The wind sounds like rain." Jenner says: + + "The _hollow_ winds begin to blow." + +And Virgil: + + "The _whispering_ grove + Betrays the gathering elemental strife." + +This whispering is the motion of the leaves; and they are often stirred by +a peculiar motion which is not that of wind. Sometimes every leaf upon a +tree may be seen _vibrating_ with an _upward and downward_ motion, when +there is not wind enough to stir a twig. This interesting phenomenon is +electrical. Trees, and all vegetables, confessedly discharge electricity, +and such discharges move the leaves, when very active. + +With us, sounds can be heard more distinctly from the east or south, +before storms, according to the character of the coming wind. Howard +mentions an instance when he heard carriages five miles off. Steamboat +paddles, rail-road cars, and other sounds, are often heard a great +distance. The distance at which the now common steam-whistle is heard, and +the direction, is not an unimportant auxiliary indication of the weather. +Howard attributes these peculiar phenomena to the "_sounding board_," made +by the _stratum of cloud_; but sounds may be heard from the north-west, +when there is no condensation, and the wind is from that quarter, and also +from the east when it is not cloudy; and in a level country the village +bells often tell the direction of the current of air just over our heads +when we do not feel it at the surface. The wind is undoubtedly moving in a +rapid, and perhaps invisible current, not far above us. If from the east +or south, it betokens rain; if from the western quarter, fair weather. + +The conduct of the different animals furnish a considerable portion of the +signs alluded to by Virgil and Jenner, and are never unimportant auxiliary +evidence of the approaching changes, whether from dry to wet, or wet to +dry. + +The observer will find, in the conduct of our birds and animals, +especially those which are not domestic, ample evidence of the truth of +the descriptions of Virgil. He denies the animals and birds foresight, but +he does not seem to have observed that the swallow leaves for the south as +soon as the _autumnal_ change begins to be felt, and in August; nor the +evident sagacity of other _migratory_ birds. They do not act from the +"_varying impulse_" produced by an actual state of things, but a knowledge +or apprehension of those which are to come. This is nothing more or less +than foresight. So foresight tends to prudence and skill, and they +exercise both, and with reference to the future. The goldfinch does not +build her nest in the hole of the tree, or in the crotch of the limb; but +_hangs it_ with _exquisite skill_ on the slender _waving, outward branch_, +where no animal, or larger bird, or any depredator, can be sustained. She +is not more timid than others; why does she invariably thus build? What +makes her "_impulses_" differ from those of other birds, and always in the +_same manner_? + +Jenner, too, has grouped, in admirably descriptive language, many of the +peculiarities exhibited by animals and birds before approaching storms, +some of which exhibit foresight, and others not. + +Perhaps the rooster, who keeps ceaseless watch over his harem, is the most +reliable weather-watcher we have. In my earlier days, when it was the +practice to keep valuable birds of the kind much longer than it now is, +and they had opportunity to become _experienced_, it was interesting to +observe how closely they watched the weather. I well remember a venerable +chanticleer, who, perched on the tree among his hens, would always +foretell the coming storm of the morrow, by sounding forth _in the +evening_, and _often_, his defiant note. Such note in the evening was +invariable evidence of foul weather. And during the night, their earlier +and more frequent crowing is often indicative of it. It is, however, in +the earlier part of the day, in doubtful cases, that no inconsiderable +reliance may be placed on their sagacity. Often, when a storm is gathering +in the forenoon, they will announce it by an almost incessant crowing. The +habits of an _experienced_, old-fashioned bird, of this kind, will well +repay attention; but I can not answer for the Shanghai and other _fancy +breeds_. + +Jenner says: + + "The leech disturbed, is newly risen + Quite to the summit of his prison." + +Few have had, or will have, opportunities to observe this, but it is +strikingly true. It is difficult to conceive how mere condensation, from +an increase of vapor in the atmosphere, should be foreseen by the leech in +his watery prison. It is obvious, I think, there is an electric change +which reaches him, as it does the whole animal creation, the once broken +bones, and the joints of Aunt Betty. Thus much of the philosophy of signs. + +_The barometer_ is a useful instrument, in connection with observations of +the other phenomena. It is especially useful to the sailor, as its +indications relative to the winds are much the most certain. But it is +not, _alone_, to be relied upon. This is well settled, although the +reasons for it have not been understood. Why it should rise sometimes +before storms, in opposition to the general rule--or fall at others +without rain--or rise occasionally during the heaviest gales, has been a +mystery, and impaired the confidence in its accuracy and usefulness even +of the class of philosophers of whom Sir George Harvey spoke, in the +sentence quoted in the introduction. But, as I have already intimated, it +is all very intelligible. + +I have said that the barometer has no fair weather standard--the mean of +30 inches at the level of the sea being an _average_ of the _fair weather_ +elevations and the _foul weather_ depressions. Its fair weather position, +it would seem, must be above the mean, therefore, and as much above as its +foul weather depressions are below. But this is not precisely true. Its +extreme fair weather range is 31 inches, and it rarely reaches that; while +its lowest storm range is down to 28, and is the most often reached of +the two. My barometer stands about 40 feet above ordinary high-water mark. +It is not a "wheel," but an open, "scale" barometer, and a perfectly good +one. Its most reliable fair weather standard is about 30-30/100 inches. It +is its _most common summer, set fair position_, but that position is often +at other and different elevations, at other periods of the year, during +fair weather. The reader must observe for his own locality, and satisfy +himself what the most common set fair position for the barometer is, at +the different periods of the year, where he resides. When he has +ascertained this, he may apply the following principles to illustrate its +exceptional action, and in judging of the future of the weather: + +1st. _As to its rise before storms._--Supposing it to have been +stationary, at or about a set fair position, _for the period_, and for one +or two or more days, a very _gradual_ and _moderate_ rise is an indication +of continued fair weather; and a _sudden_ and _considerable rise_ is +indicative of a storm. If the sudden and considerable rise occurs in the +latter part of spring, summer, or early autumn, it indicates a storm of +the _first_ or _third classes_ described in Chapter X., if in winter, a +storm of the _first class_ only. If the elevation is _very_ sudden and +considerable, the storm will probably be _severe_. The philosophy of this, +according to my present apprehension of it, is, that these storms present +an _extended easterly front_--_settle very near the earth_--and _have a +rapid progress_--thus accumulating the atmosphere somewhat, in advance of +them. + +2d. _As to its fall before storms without previous rise._--This is always +very regular before the second class of storms, or polar belts of showers +and storms. It is very fairly exemplified in the table from Reid, on page +329. The barometer, so far as I have opportunity to observe, does not rise +from a stationary position on the approach of this class of storms. At the +commencement of heated, summer, dry terms, my barometer has most +frequently ranged at about 30.30, and gradually, but slowly, fallen below +30 inches before the belt of showers arrived, and the term closed. The +fourth rule of Dalton (Meteorology, page 183) indicates a similar law in +England. It is as follows: + + "In summer, after a long continuance of fair weather, with the + barometer high, it generally falls gradually, and for one, two, or + more days, before there is much appearance of rain. If the fall be + sudden and great for the season, it will probably be followed by + thunder." + +3d. _It falls frequently and considerably without rain._--This is owing to +the fact that _all_ regular, periodic efforts at condensation do not +result in rain. The second, third, and fourth classes of storms described, +may not (as we have said) _be sufficiently active to precipitate_, +although the _series of phenomena_ (including the fall of the barometer) +may be, in other respects, perfect. Such an instance may be found in +Reid's table, on page 329, and on the 11th of the month. But the fall in +such cases is not as great, unless the wind be violent. + +4th. _It rises during considerable gales._--But these are of the kind so +often alluded to--viz., the N. W., in the northern hemisphere, and the S. +W., in the southern; and the _philosophy_ of it has been explained, and is +observable. + +With these explanations, the reader will be able to understand, and +practically apply, the barometric changes, in connection with the other +phenomena, in forming an opinion of the weather. + +_The thermometer_ is also an auxiliary. It _rises_, during the winter half +of the year, in the _advance portion of the storm_, and falls when it +passes off again; and the reverse is true, as we have seen, when its range +is very high in summer. It is, therefore, to some extent, a useful +auxiliary, although of minor importance. + +_The hygrometer_ is of less importance still. It is not in general use as +a practical guide to the changes of the weather, and does not deserve to +be. + +A question, which has been much mooted, deserves a passing notice in this +connection--viz., whether our climate has gradually become ameliorated and +milder on the eastern part of our continent, since its settlement. I have +not space left for its discussion. Humboldt (Aspects of Nature, page 103) +is of opinion that there has been no material change. He says: + + "The statements so frequently advanced, although unsupported by + measurements, that since the first European settlements in New + England, Pennsylvania, and Virginia, the destruction of many forests + on both sides of the Alleghanys, has rendered the climate more + equable--making the winters milder and the summers cooler--are now + generally discredited. No series of thermometric observations worthy + of confidence extend further back, in the United States, than + seventy-eight years. We find, from the Philadelphia observations, + that from 1771 to 1824, the mean annual heat has hardly risen 2°.7 + Fahrenheit--an increase that may fairly be ascribed to the extension + of the town, its greater population, and to the numerous + steam-engines. This annual increase of temperature may also be owing + to accident, for in the same period I find that there was an increase + of the mean winter temperature of 2° Fahrenheit; but, with this + exception, the seasons had all become somewhat warmer. Thirty-three + years' observation, at Salem, in Massachusetts, show scarcely any + difference, the mean of each one oscillating within 1° of Fahrenheit, + about the mean of the whole number; and the winters of Salem, instead + of having been rendered more mild, as conjectured, from the + eradication of the forests, have become colder, by 4° Fahrenheit, + during the last thirty-three years." + +The facts hereinbefore stated show that there is nothing like a _regular_ +amelioration; that the seasons differ during the same decade, and +different decades. The cold decade, from 1811 to 1820, has not been +reproduced. But it may be, and we know not how soon. Since that period +there has certainly been a change--for even the cold period from 1835 to +1840 did not equal that from 1815 to 1820, nor indeed those of 1775 to +1780 or 1795 to 1800. But as these variations, so far as we are enabled to +judge, depend upon the varying influence of the sun's rays, and of +volcanic action, it is impossible to say that equally cold periods will +not return, during the latter half of this century. + +If the influence of the sun was constant, and volcanic action regular, two +causes would tend to modify the seasons: + +1st. The exposure of the surface to a more effective action of the solar +rays, by a removal of the forests, and by drainage. That such action would +be more effective upon a surface thus uncovered and drained, can not be +doubted. + +2d. _The movement of the area of magnetic intensity, and the magnetic +pole, to the west._--There is such a movement, and its progress can be +measured by the increase of declination on the east of it, and its +decrease on the west. And the effect of it on climate is unquestionable. +In all probability it has had an influence upon ours; and a removal of +that area and pole still further west--60° or 80°--would change the +location of the concentrated trade, and the Gulf Stream, and restore to +Greenland the fertility she once had, and which the Faroe Islands now +enjoy. And, on the other hand, its removal as far east of its present +position would again depopulate Greenland, and render it again +inaccessible. But I can not pursue this subject. + +Finally, assistance may be derived from the occasional, although +imperfect, accounts of the state of the weather elsewhere, which the +newspapers afford. I have been much indebted to the Associated Press of +New York for intelligence contained in their telegraphic reports. +Occasionally they have been very full and instructive. + +On this point, however, there is less of reality in the present than of +hope in the future. The time must come when the collection and +dissemination of meteorological truth, will be deemed an object of +national importance, and national duty. Population is increasing, by +immigration and propagation, in a rapidly progressive ratio. There has +been great danger that it would outrun agricultural production. A short +crop this year would have been disastrous to our prosperity--and the +danger was imminent. Every description of business, and every financial +circle, felt that fever of anxiety it was so well calculated to induce. +The importance of extended agricultural production, and the dependence of +all classes upon its success, are now in a greater measure appreciated; +and none can fail to see the value of a correct understanding of the +weather to the agriculturist, how short-sighted soever they may be, in +relation to its direct influence upon their own prosperity and happiness. + +Our country is, physically, a most favored one. The facts disclosed or +alluded to in this volume show that it is without a parallel on the face +of the globe; and our facilities for meteorological observation, and the +ascertainment and practical application of meteorological truth, are +equally pre-eminent. The great extent and unbroken surface of the eastern +portion of the continent; its excessive supply of magnetism and +atmospheric currents, and the consequent marked character of the +phenomena; the existence and prospective increase of telegraph lines over +most of its surface; the homogeneous and energetic character of a +population united, upon so large a surface, under one government; the +freedom of that government from debt, and the excess of its revenue; the +possession of a National Observatory, with a competent philosopher at its +head; and a national institution, liberally endowed, and adapted to the +collection and diffusion of practical and scientific intelligence, give +us an opportunity and a capacity for connected observation and +investigation, and an ability to profit by it, that no other nation can +boast. + +We have, too, a just national pride. Our exploring ships have penetrated +and made discoveries in both hemispheres, and our travelers have visited +successfully every clime; and thus our national interests, and +obligations, and pride, demand an organization, practical and permanent, +in relation to this subject, and the time will come when we shall have it. + +When that time comes--when the present _limited horizon_ of each of us is +_practically extended over the entire country_--and when the actual state +of the weather over every part of it is known, at the same time, to the +inhabitants of every other, and every where _read in the light of a +correct philosophy_, prognostication will be comparatively simple and +certain; and A PROGRESS will have been made, productive of an amount of +pecuniary, intellectual, and social benefit to the people, which can not +be overestimated. May it come before the shadows of the night of death +have gathered around us, that we may have a more perfect view of that +atmospheric machinery which distinguishes our planet from others, and is, +with such infinite wisdom, adapted to make it a fit habitation for man! + + +THE END. + + + + +APPENDIX. + + +Since this work was completed I have received a very valuable publication, +entitled, the "Army Meteorological Register." It is a compilation of the +observations made by the officers of the medical department of the army, +at the military Posts of the United States, from 1843 to 1854 inclusive, +prepared under the supervision of the Surgeon-general, and published by +direction of the Secretary of War. To this, there is appended a report or +general review of the prominent features of American climatology, so far +as the basis afforded by the published observation of the army medical +Bureau would warrant positive deduction, by Mr. Lorin Blodget, a +distinguished meteorologist, accompanied by temperature and rain charts, +for each of the four seasons;--exhibiting the various local differences +and peculiarities relative to temperature and precipitation in each. + +These local differences and peculiarities and contrasts are deduced and +delineated by Mr. Blodget with much ability. He was fettered, however, by +the prevailing calorific theories, and the unfortunate practice of +grouping the phenomena into means for the seasons, Spring, Summer, Autumn, +and Winter, which grouping is arbitrary, and comparatively uninstructive. +Hence, he failed to discover what the tables and summaries most clearly +disclose--the principles and system unfolded in the foregoing work. + +But the summaries of this register contain observations made at posts in +Western and Southwestern Texas, in Kansas and Nebraska, and in New Mexico +and California, where there has been a dearth of such observations +hitherto, and enable me to demonstrate, more conclusively, and I think so +that none can fail to understand it, the truth of the philosophy I have +endeavored to exhibit. + +To do this, I will take a _year_,--divide it into two seasons, the periods +of northern and southern transit, the only natural and correct +division--and note the phenomena in each, as each progresses. + +And I will take the year 1854, because that is the last year for which the +record of observation is complete; because it had marked peculiarities +which are remembered; and because I have alluded to those peculiarities, +and those allusions should be confirmed or disproved by the record. Unless +I mistake exceedingly, the confirmation will be found signal and +convincing. + +I have assumed, pp. 187, 351, that the transits were greater in some +seasons than others; that the drought of 1854 was owing to an extreme +northern transit, or to an extension west of the concentrated +counter-trade, or both, leaving us less supplied with moisture than +usual. + +In point of fact, it appears from these observations that it resulted from +_both_ causes, operating _connectedly_; and the annals of Science rarely +furnish a more striking instance of analogical inference proved true by +subsequent investigation. + +Commencing then with the commencement of the northern transit about the +1st of February, we are enabled to trace the then location of our +concentrated trade, and its subsequent progress to the north till August, +and its influence upon temperature and precipitation. And we can also +trace the situation during the same period, of the intervening drought, +and the inter-tropical belt of rains, and the extension of the latter +north over Florida and the cotton-planting States. + +On the 1st of February, 1854, our counter-trade was somewhat more +concentrated on its extreme winter curve, over the Southern States, than +usual. Its line of excess reached up from Fort Brooke, on the peninsula of +Florida, to the northwest, a little east of Pensacola on the gulf, cutting +Mount Vernon Arsenal north of Pensacola, and extending thence +north-westwardly on to Eastern Louisiana, and curving thence and passing +N. E. or E. N. E., to the Atlantic, about the waters of the Chesapeake +Bay. It thinned out to the west over New Orleans and Baton Rouge, +supplying them moderately, but did not extend to the forts of Texas on the +west, nor the posts in the Indian Territory at the N. W. It was east of +Fort Towson, which is the south-eastern one. It did not reach St. Louis on +the north, nor extend north of the Ohio River, as will appear from the +tables hereinafter given. The following cut shows substantially its +situation on the 1st of February. + + +[Illustration] + + +Now, during the month of January, we find the following state of things. +_Under_ this concentrated trade, the temperature was above the mean, even +if Forts Monroe and McHenry on the Atlantic are included; but Mr. Blodget +discredits their returns, and some others which do not conform to general +results. On the west and north of its curving line, both precipitation and +temperature were below the mean. + +Under the counter trade, we have the following stations, with their actual +and mean temperature. I have inserted the temperature for several +subsequent months, to show a depression in April. + + +TABLE I. + + ------------------------------------------------------------------------- + | LAT. | LON. | JAN. | FEB. | MAR. | APRIL.| MAY. | + ------------------------------------------------------------------------| + Fort Moultrie | 32.45 | 79.51 | 50.83 | 53.09 | 62.72 | 62.76 | 73.35 | + Mean of 28 yrs.| | | 50.36 | 52.41 | 58.68 | 65.44 | 73.42 | + Fort Pierce | 27.30 | 80.20 | 67.91 | 67.33 | 73.01 | 71.10 | 78.41 | + Mean of 5 yrs. | | | 62.75 | 64.42 | 69.77 | 73.63 | 76.92 | + Fort Meade | 28.01 | 82.00 | 63.75 | 63.33 | 70.64 | 68.10 | 76.31 | + Mean of 3 yrs. | | | 58.40 | 63.23 | 69.02 | 69.89 | 76.69 | + Fort Brooke | 28.00 | 82.28 | 62.94 | 62.36 | 70.06 | 70.07 | 77.49 | + Mean of 25 yrs.| | | 61.53 | 63.54 | 67.72 | 71.82 | 76.64 | + Fort Myers | 26.38 | 82.00 | 67.56 | 67.39 | 73.74 | 71.07 | 79.13 | + Mean of 4 yrs. | | | 63.39 | 67.98 | 72.19 | 73.86 | 80.13 | + Key West | 24.32 | 81.48 | 71.75 | 71.95 | 76.56 | 73.89 | 80.84 | + Mean of 14 yrs.| | | 66.68 | 68.88 | 72.88 | 75.38 | 79.10 | + Fort Barrancas | 30.18 | 87.27 | 54.71 | 54.56 | 64.98 | 62.93 | 75.40 | + Mean of 17 yrs.| | | 53.61 | 55.58 | 61.80 | 68.51 | 75.45 | + Mt. Vernon Ars'l| 31.12 | 88.02 | 51.52 | 53.18 | 65.24 | 62.30 | 74.64 | + Mean of 14 yrs.| | | 50.44 | 53.69 | 60.26 | 66.87 | 73.92 | + Baton Rouge | 30.26 | 91.18 | 53.43 | 56.48 | 66.24 | 64.63 | 75.10 | + Mean of 24 yrs.| | | 53.47 | 55.02 | 61.93 | 69.30 | 75.60 | + ------------------------------------------------------------------------- + + ------------- + JUNE. | JULY. + ------------- + 78.55 | 82.06 + 79.01 | 81.72 + 82.09 | 84.16 + 79.02 | 82.50 + 79.10 | 80.17 + 78.24 | 79.76 + 80.51 | 81.08 + 79.46 | 80.72 + 82.35 | 81.91 + 81.25 | 82.87 + 83.34 | 83.30 + 81.63 | 83.00 + 81.00 | 84.55 + 80.80 | 82.26 + 79.17 | 78.90 + 78.03 | 78.62 + 80.61 | 80.09 + 80.56 | 81.81 + ------------- + +It will be seen that the temperature was above the mean in January at +every post except Baton Rouge, and there it was at the mean. We shall see +hereafter that Baton Rouge was near its western line. + +Under this trade during this month, and at the same posts, the fall of +rain was as follows, compared with the mean:-- + + +TABLE II. + + -------------------------------------------------------------- + | JANUARY. | FEBR'Y. | MARCH. | + -------------------------------------------------------------- + | 1854. | Mean.| 1854. | Mean.| 1854.| Mean.| + -------------------------------------------------------------- + Key West. | 1.77 | 2.86 | 2.55 | 1.38 | 0.51 | 4.21 | + Fort Myers. | 1.15 | 3.90 | 4.70 | 2.16 | 0.20 | 4.60 | + " Brooke. | 3.88 | 2.20 | 6.89 | 3.01 | 2.44 | 3.37 | + " Mead. | 1.30 | 1.07 | 2.21 | 1.01 | 1.85 | 1.64 | + " Pierce. | 3.55 | 4.45 | 3.40 | 2.72 | 1.05 | 3.01 | + " Barrancas. | 3.45 | 3.87 | 5.55 | 4.95 | 7.21 | 5.87 | + Mt. Vernon Ars'l | 11.01 | 6.80 | 12.83 | 6.04 | 6.22 | 4.59 | + Baton Rouge. | 2.85 | 5.26 | 5.50 | 4.91 | 6.15 | 4.68 | + Fort Moultrie. | 3.80 | 2.39 | 2.84 | 2.33 | 0.25 | 4.06 | + -------------------------------------------------------------- + + ------------------------------------------- + | APRIL. | MAY. | JUNE.| JULY. + | 1854.| Mean.| 1854. | Mean.| | + ------------------------------------------- + | 2.99 | 1.55 | 3.14 | 2.58 | 4.54 | 3.45 + | 2.75 | 3.14 | 5.65 | 3.33 | 6.75 | 9.70 + | 8.82 | 1.95 | 6.21 | 3.24 | 9.44 | 15.53 + | 3.19 | 1.78 | 10.51 | 5.34 | 7.24 | 8.55 + | 7.00 | 3.85 | 5.70 | 4.27 | 6.63 | 4.97 + | 0.50 | 2.94 | 3.47 | 4.05 | 3.39 | 5.43 + | 1.96 | 4.21 | 4.45 | 4.62 | 6.72 | 6.13 + | 3.58 | 5.22 | 8.05 | 5.18 | 4.00 | 6.55 + | 2.20 | 1.75 | 3.70 | 4.08 | 4.20 | 5.69 + ------------------------------------------- + +It will be observed that in February the counter-trade and extra-tropical +belt had moved up from Key West, and a drought, which sometimes intervenes +between the concentrated counter-trade and the inter-tropical belt, +appeared there in February and March. In April, the inter-tropical belt +appeared at that point, and went on increasing till September. As the +counter-trade commenced moving north in February, an increased +precipitation above the mean commenced at all the more southern stations +under the concentrated-trade--an earnest of that irregularity which +followed, and marked the season as the most excessive of the century. + +In March, the intervening drought appeared at the other posts on the +peninsula, and also at Fort Moultrie, followed _much more closely than +usual_, by the inter-tropical belt of rains. In April, the drought +appeared at Fort Barrancas and Mount Vernon Arsenal (the wave of +precipitation having moved to the west), and slightly in comparison at +Baton Rouge. + +If now we look at the condition of things, _west_ and _north_ of the +curving line of concentrated trade, from Fort Brown, at the mouth of the +Rio Grande, in South-western Texas, through that State, the Indian +Territory, Arkansas, Missouri, Kentucky, and Northern Pennsylvania, to the +Atlantic, we find the thermometer every where in January below the mean. +The following table will show this, and the precipitation for that month +and February:-- + + +TABLE III. + + ------------------------------------------------------------------------ + | JANUARY. | FEBRUARY. | MARCH. | + |-----------------------------------------------| + | 1854. | Mean. | 1854. | Mean. | 1854. | Mean. | + -----------------------------------------------------------------------| + _Western Texas._ | | | | | | | + Fort Brown | 59.34 | 60.41 | 62.45 | 63.63 | 71.87 | 68.95 | + " Ewell | 50.47 | 52.92 | 58.12 | 57.61 | 70.34 | 67.00 | + " Inge | 47.24 | 49.46 | 56.04 | 55.39 | 67.54 | 62.63 | + | | | | | | | + _Indian Territory._ | | | | | | | + Fort Towson. | 36.32 | 43.14 | 49.29 | 45.97 | 59.55 | 53.40 | + Forts Gibson, Washita, | | | | | | | + and Arbuckle, in much| | | | | | | + the same proportions.| | | | | | | + | | | | | | | + _Arkansas._ | | | | | | | + Fort Smith. | 33.92 | 40.18 | 47.01 | 43.89 | 57.01 | 51.58 | + | | | | | | | + _Missouri._ | | | | | | | + St. Louis Arsenal. | 25.47 | 31.44 | 36.66 | 33.43 | 46.10 | 42.30 | + | | | | | | | + _Kentucky._ | | | | | | | + Newport Barracks. | 31.75 | 34.04 | 39.60 | 36.94 | 46.74 | 45.46 | + | | | | | | | + _Pennsylvania._ | | | | | | | + Allegheny Arsenal. | 29.08 | 29.25 | 33.49 | 31.16 | 40.36 | 39.02 | + | | | | | | | + _Delaware._ | | | | | | | + Fort Delaware | 32.38 | 33.67 | 34.56 | 35.84 | 43.18 | 42.90 | + | | | | | | | + _New York Harbor._ | | | | | | | + Fort Columbus. | 28.71 | 30.18 | 28.17 | 30.44 | 36.17 | 38.28 | + ------------------------------------------------------------------------ + + -------------------------------------- + | Rain in January. | Rain in February. + -------------------------------------- + | 0.45 | 1.50 + | 0.22 | 2.86 + | 0.20 | 2.15 + | | + | 1.01 | 2.00 + | | + | 1.37 | 2.05 + | | + | 0.65 | 2.40 + | | + | 3.20 | 5.30 + | | + | 2.23 | 2.33 + | | + | 2.30 | 5.45 + | | + | 2.60 | 4.00 + -------------------------------------- + +We find, also, from this and table first, that every where, except at Fort +Brown, and upon the Atlantic coast, the temperature had risen above the +mean in February. + +The situation of the belt which supplied the western coast in winter, and +its excess of precipitation, are also represented upon the cut. The +intervening area was not without counter-trade and precipitation--the +latter, of course, greatest over the area of intensity--but they were +_comparatively_ less, as the tables will show. + +The following cut and table show the situation of the concentrated +counter-trade in March. + + +[Illustration] + + +TABLE IV. + + ------------------------------------------------------------------------ + | JAN.|FEBR.| MAR.| APR.| MAY.|JUNE.|JULY. + ------------------------------------------------------------------------ + Fort Barrancas, Pensacola Bay| 3.45| 5.55| 7.21| 0.50| 3.47| 3.39| 5.43 + Mean. | 3.87| 4.95| 5.87| 2.94| 4.05| 4.66| 6.80 + Baton Rouge, Louisiana | 2.85| 5.50| 6.15| 3.58| 8.05| 4.00| 6.55 + Mean. | 5.26| 4.91| 4.68| 5.22| 5.18| 5.52| 7.42 + Fort Towson, Indian Territory| 1.01| 2.00| 5.10| 2.22|Recr'd stops here. + Mean. | 3.13| 2.97| 4.38| 5.33| | | + Fort Gibson, Indian Territory| 0.30| 1.43| 7.83| 3.16| 7.67| 2.80| 0.21 + Mean. | 1.33| 2.26| 2.54| 4.19| 4.65| 4.30| 2.75 + Fort Smith, Arkansas | 1.37| 2.05| 7.05| 6.55| 6.25| 2.26| 1.02 + Mean. | 1.96| 2.17| 2.92| 5.10| 4.46| 4.74| 3.82 + St. Louis Arsenal | 0.65| 2.40| 7.10| 4.30| 4.65| 2.20| 1.70 + Mean. | 1.93| 3.37| 3.82| 4.16| 4.88| 6.94| 0.04 + Newport Barracks, Kentucky | 3.20| 5.30| 8.10| 2.10| | | + (No Mean given.) | | | | | | | + ------------------------------------------------------------------------ + +We see from this table that its focus had extended west in Florida over +Fort Barrancas, and over Baton Rouge in Louisiana; N. W. to Forts Towson +and Gibson in the Indian Territory, and Smith in Arkansas; north to St. +Louis Arsenal at St. Louis, and to Newport barracks in Kentucky; but it +was spread over a larger surface east of the mountains. Its greatest +progress for the month, was a west and north-west progress. + +In April, we find it had progressed rapidly west and north-west, and its +position is shown by the following cut and table. + + +[Illustration] + + +TABLE V. + + ------------------------------------------------------------------------ + | JAN.|FEBR.| MAR.| APR.| MAY.|JUNE.|JULY. + ------------------------------------------------------------------------ + Fort Riley, Kansas. | 0.00| 0.94| 1.86| 4.55| 4.35| 1.10| 0.00 + Fort Leavenworth, Kansas. | 0.04| 1.78| 1.33| 3.35| 5.55| 4.50| 0.18 + Mean | 0.72| 1.01| 1.61| 2.74| 3.62| 5.80| 3.15 + Alleghany Arsenal, Pittsburgh | 2.23| 2.33| 2.82| 4.21| 2.24| 2.06| 1.45 + Mean | 2.18| 2.17| 2.70| 3.10| 3.58| 3.56| 2.97 + Fort Columbus, New York Harbor| 2.60| 4.00| 0.70| 8.80| 7.70| 2.20| 1.90 + Mean | 2.78| 2.92| 3.44| 3.33| 4.78| 3.46| 3.17 + Fort Independence, Boston | 2.50| 3.36| 2.55| 5.40| 4.28| 2.00| + West Point. | 3.52| 5.04| 2.81|10.53| 2.00| 1.62| + Mean | 3.50| 3.44| 3.71| 4.55| 6.18| 4.79| + ---------------------------------------------------------------------- + +We see, too, that both east and west of the mountains, its focus of +precipitation was one month in advance of the mean. At all the stations +where the greatest fall was in March, it should have been in April, and +the fall at those points was greatly in excess of the usual quantity. And +the same was true of stations reached in April. The concentrated trade, +instead of spreading out, and precipitating over the whole south-eastern +portion of the continent (its normal condition), was gathered into a wave +of greater volume, resulting in greater precipitation, and was rapidly +hastening its curve to the west over Texas, and to the north-west over the +Indian Territory, and northward on its usual curve to the north and east +of them. + +The observations for April disclose another singular and instructive +condition. The temperature, that had every where been above the mean in +March, fell below it in April under the concentrated trade. And snow fell +on three days in some localities, and four in others. + +Along the Ohio River, it fell to the depth of 8 to 10 inches on the 17th, +and east of the mountains to a greater depth on the 18th, one day later. +It fell to the depth of 4 inches at Marietta on the 29th also. Dr. +Hilldreth, American Journal of Science for March, 1855, says:-- + +"It is a singular fact that the deepest snow, 8 inches, fell on the 17th +of April, and at the head waters about Pittsburg over a foot. Also, on the +29th of the month, at Marietta, 4 inches, a very rare occurrence." This +depression of the temperature was quite general, but the fall of snow was +local. The latter was north of a line drawn from Fort Laramie, at the base +of the Rocky Mountains, in an E. S. E. direction--north of Forts Kearney +and Leavenworth, and of St. Louis, but south of Newport barracks in +Kentucky, and from thence to the Atlantic. Snow fell at every station +north of this line, at no station south of it. The depression of +temperature, however, was experienced over the continent, east of the +Rocky Mountains, under, and south of, the belt of precipitation. Now what +occasioned this general depression of temperature, and local fall of snow? +It will not do to say, as perhaps some calorific theorist may be inclined +to say, because the concentrated trade had been carried up where it was +cold, a month too soon; or that the sun had heated the land in advance of +it, and drawn it up. + +For, 1st, it might be asked how, if it was warm enough to draw it up, +could it be cold enough to make it snow; or, 2d, how happened it to start, +when, as we have seen, it was warmer than the mean under it, and colder +than the mean to the north and west of it, when it commenced its journey? + +But again, it snowed at posts north of the line, while the thermometer +remained above the mean; and the thermometer fell below the mean down to +Fort Brown in south-western Texas, and at Key West in the southern part of +Florida; and what is more remarkable still, at Key West, Fort Barrancas, +and every other south-eastern station, except Forts Brooke and Moultrie, +it not only fell below the _mean_ of the month, but _below the actual +temperature of March_. (See Table I.) At Forts Brooke and Moultrie it did +not rise above that temperature. West of the Rocky Mountains the +depression was not felt; nor at stations north, or north-west of the belt +of precipitation. + +It is obvious, the calorific theory can furnish no rational explanation of +this matter; for the reason that, whatever the cause, it operated not +only under, but south, and far south of the belt of precipitation. It +could not have been spots upon the sun, or other general cause, for then +it would have operated in New Mexico and California, and at the +north-western stations. It operated most intensely in Florida and the +South-Eastern States, which approach most nearly the volcanic areas of +South America and the West Indies. I believe it to have been occasioned by +volcanic action affecting the local magnetism of our intense area; but it +is a most important development, and should be thoroughly investigated. We +may find in it the key to the mysterious, but unquestionable, influence of +volcanic upon magnetic action; and I hope the distinguished +surgeon-general will cause the records of that month to be published "in +extenso." + +In May and June, the trade became more concentrated, a perfectly developed +belt from the Rio Grande to the Lakes and British possessions, and +doubtless to the Atlantic, with every where a central focus of excessive +precipitation, gathering to itself in one vast wave the current that +should have been spread out over the whole country; and leaving every +where on its eastern and southern borders, down to the northern edge of +the inter-tropical belt of rains--(which extended up to lines drawn from +Baton Rouge to Charleston)--a _perfectly well developed_ and _defined +drought_. That drought will long be remembered. The following cuts show, +approximately, the location of the belt of precipitation and drought for +those months, and the table which follows will show their correctness. + +The tables also show that this wave was occasionally a double, or divided +one--evinced by an intervening _partial_ precipitation. Tables IV., V., +and VI., also show the commencement of the drought at the several +stations, as the wave moved to the west and north. + + +[Illustration: MAY.] + + +[Illustration] + + +TABLE VI. + + JAN. FEBR. MAR. APR. MAY. JUNE. JULY. AUG. SEPT. + Fort Brown 0.45 1.50 1.15 0.05 4.10 7.65 4.25 5.00 11.31 + Mean 1.61 2.25 1.20 0.56 2.21 4.55 1.95 2.76 6.73 + Ringgold Barracks 0.70 1.69 0.22 0.00 2.83 10.98 4.06 1.58 3.02 + Mean 1.24 1.18 0.72 1.08 2.09 3.47 3.18 1.50 3.22 + Fort Merrill 0.11 1.99 0.05 1.16 7.66 4.70 5.44 3.13 5.01 + Mean 0.23 2.09 0.09 1.62 3.43 4.10 6.13 3.40 4.60 + Fort Duncan 0.05 0.69 1.50 0.00 2.53 6.83 0.83 0.90 4.81 + Mean 0.26 1.27 1.34 0.71 1.50 5.63 3.35 0.93 3.28 + Fort Inge 0.20 2.15 3.00 0.75 3.88 2.09 0.97 1.67 4.80 + Mean 0.64 2.21 1.79 1.26 3.01 5.38 3.66 2.02 2.21 + Fort McKavet 0.01 0.77 2.10 0.28 3.72 0.15 2.91 0.04 3.86 + " Belknap 0.11 1.10 1.42 1.75 4.97 8.33 0.00 0.75 1.53 + " Massachusetts, + Northern New + Mexico 3.93 0.24 2.14 2.61 1.53 + Fort Kearney 0.23 1.33 1.87 2.56 4.15 5.40 3.51 1.18 4.60 + Mean 0.50 0.48 1.55 2.68 6.57 4.36 5.07 2.62 1.83 + Fort Laramie 0.18 0.40 0.80 3.98 4.46 3.67 3.26 1.27 1.60 + Mean 0.27 0.71 1.37 1.93 5.39 2.95 1.83 0.92 1.33 + Fort Ridgley 1.20 0.01 1.18 2.83 6.84 2.70 2.49 2.28 2.58 + " Snelling 0.72 0.03 1.03 2.51 4.30 3.31 3.92 1.75 6.55 + Mean 0.73 0.52 1.30 2.14 3.17 3.63 4.11 3.18 3.32 + Fort Ripley 0.67 0.03 0.79 0.97 4.34 3.68 0.62 1.69 4.40 + Mean 0.86 0.37 1.80 1.42 3.09 5.15 5.20 2.27 4.92 + Fort Mackinac 2.59 1.23 1.56 1.04 2.65 6.35 5.67 4.26 3.22 + Mean 1.25 0.82 1.14 1.21 2.32 2.81 3.20 2.87 2.97 + Fort Brady 2.49 1.18 1.34 2.14 3.61 1.23 3.21 3.86 3.18 + Mean 1.84 1.13 1.37 1.83 2.24 2.83 3.73 3.39 4.33 + Fort Niagara 1.63 2.52 1.87 2.25 3.90 1.71 4.08 1.52 2.61 + Mean 2.25 1.89 2.12 2.20 2.55 3.28 3.49 3.04 3.95 + +But the belt of trade continued its progress to the west and north, and +during the months of July and August the drought extended in both +directions, reaching, in August, from Mississippi, Alabama, Georgia, and +South Carolina, to the Lakes, and from the Rocky Mountains to the +Atlantic. Its position is shown by the following cut, and the position of +the belt of precipitation by the following table. + +[Illustration] + + TABLE VII. + + _Situation of the focus of Precipitation in July and August._ + + ----------------------------------------------------------- + | JUNE.| JULY.| AUG. | SEPT.| OCT. + ----------------------------------------------------------- + _New Mexico._ | | | | | + | | | | | + Fort Thorne | 0.08 | 2.23 | 6.01 | 3.50 | 0.00 + Albuquerque | 0.28 | 2.50 | 1.19 | 2.67 | 1.37 + Santa Fe | 0.32 | 4.11 | 3.86 | 4.06 | 2.50 + Fort Defiance | 1.24 | 3.94 | 5.24 | 3.47 | 0.62 + " Yuma | 0.00 | 0.01 | 2.37 | 0.17 | 0.30 + San Diego | 0.02 | 0.07 | 1.35 | 0.13 | 0.01 + Fort Snelling, Minnesota | 3.31 | 3.92 | 1.75 | 6.35 | 1.23 + " Brady | 1.23 | 3.21 | 3.86 | 3.18 | 3.40 + " Mackinac | 6.35 | 5.67 | 4.26 | 3.22 | 2.28 + ----------------------------------------------------------- + +I have not space for all the comment which this exposition is calculated +to induce. The reader will not only find in it an explanation of the +extraordinary character of the summer of 1854, but will see from the +_means_, that it was but an _excessive development_ of an ANNUAL +PHENOMENON,--THE PROGRESS OF A CONCENTRATED COUNTER-TRADE. + +It is not necessary to follow with particularity the return transit. It +required no great degree of sagacity to predict, at the time, that the +drought would continue in the vicinity of New York till about the 10th of +September. The return of the belt to that latitude, was not to be expected +before that time, and the drought continued, in fact, until the 9th of +September. + +Its return progress was slow, and it was every where behind time. The +autumn was warm, and so, indeed, were December and January, west of the +area of magnetic intensity, although upon, and east of it, there was a +depression in December. The retreating but lingering edge of +counter-trade, with its excess of snow for the season, caught the Iron +Horse, with its train and passengers, upon the prairies of the west, and +laid its embargoing hands upon them. Few, if any, can have forgotten the +thrilling accounts which reached us from that section, of the sufferings +endured by those who were thus embargoed for days and nights, far from the +comfortable habitations of their fellow men. + +But the return transit, though slow, was extreme, and February and March +were exceedingly cold for the season. The transit to the north, again, did +not commence as early as usual, and the spring was backward, and the +summer cool. Both were without irregularity, and the season was +productive. The following table exhibits the temperature on a line of +posts, running north and south at the west, during the winter months of +1855, and will illustrate what has been said. + +TABLE VIII. + + --------------------------------------------------- + 1855. |JANUARY |FEBRUARY.| MARCH.| APRIL. + --------------------------------------------------- + Key West | 67.18 | 65.94 | 70.28 | 75.09 + Mean | 66.58 | 68.88 | 72.88 | 75.38 + Fort Snelling | 17.09 | 12.62 | 25.30 | 49.86 + Mean | 13.76 | 17.57 | 31.41 | 46.34 + Fort Kearney | 23.55 | 25.69 | 32.86 | 54.39 + Mean | 21.14 | 26.11 | 34.50 | 47.13 + Fort Laramie | 35.85 | 29.01 | 36.41 | 52.94 + Mean | 31.03 | 32.60 | 36.81 | 47.60 + Fort Arbuckle | 41.94 | 39.86 | 49.09 | 67.43 + Mean | 39.10 | 43.69 | 53.22 | 61.85 + Fort Belknap | 45.92 | 44.49 | 53.09 | 70.00 + Mean | 42.80 | 47.47 | 56.90 | 65.79 + Fort Chadbourne | 48.89 | 45.87 | 56.68 | 68.51 + Mean | 44.29 | 46.75 | 58.01 | 65.52 + Fort McKavitt | 46.74 | 44.51 | 53.66 | 67.05 + Mean | 44.75 | 46.87 | 57.39 | 66.25 + Fort Merrill | 54.51 | 54.65 | 61.82 | 74.50 + Mean | 54.82 | 57.20 | 68.66 | 73.27 + Fort Brown | 60.23 | 61.60 | 66.24 | 74.98 + Mean | 60.41 | 63.63 | 68.95 | 75.05 + Fort Inge | 52.21 | 50.63 | 61.22 | 74.48 + Mean | 49.46 | 55.39 | 62.63 | 68.02 + --------------------------------------------------- + +The return transit to the south for this winter, 1855-6, has been an +extreme one. It is too early yet (Feb. 18th) to write its history, but the +extreme southern transit is as obvious as the unusual severity of the +cold. The rains which usually fall upon the Southern States are +precipitated further south upon the West Indies, and threaten a +deterioration of their sugar crop. The snow, and cold winds, and ice, of +the middle latitudes, are felt even in Florida. Our sheet of +counter-trade has been exceedingly thin, and the barometer has ranged, in +fair weather, much below the mean. Occasional, and for a part of the time, +_weekly_ periods of an increase of its volume, with a corresponding +elevation of the barometer, and a consequent moderation of the intense +cold, and a storm, have occurred. But those periods have been few and +brief. No regular thaw has yet occurred. From the 26th of December to this +date, at Norwalk, there have been but two periods when the wind has blown +from the south-west with sufficient force to stir the limbs of the trees. +There has been no wind from south of that point, or east of north-east; +and even our storm-winds, with one exception, have been north of +north-east--owing to the situation of the focus of precipitation far to +the south of us--and there is reason to fear that a cold summer like those +of 1816 and 1836 may follow. If this extreme transit is owing to defect in +the influence of the sun, from spots, or other causes, such will probably +be the result. If from volcanic action at the south, the influence of that +action may cease, and a rapid return transit, and an ordinary season, may +follow. Believing in the laws of periodicity in relation to the weather +and disease, I planted an early kind of corn (the Dutton), in 1836, and +had a crop when few around me succeeded. We must watch this return +transit, with hope, indeed, but not without fear, and be wise in time. + +There is a mass of other evidence in these summaries which shows the truth +of what I have written. There is not a deduction of Mr. Blodget which it +will not explain. The ascent of the summer lines of temperature to the +west is explained by the diminution of magnetic intensity. Their descent +in winter by the location and attractions of the concentrated trade. The +excess of precipitation in Alabama and Mississippi by the succession of +summer and winter belts. That of the interior of the Atlantic slope in +summer, by the showers which fall upon the elevations; and of the coast, +by the easterly storms and their attraction of the surface atmosphere of +the ocean, at other seasons. But I cannot further particularize. Even the +influence of the spots is clearly demonstrated by the observations at +_interior stations_, which were unaffected by contiguous oceans or +elevations. At Forts Washita, Gibson, Scott, Smith, and others, the years +1847 and 1848 were below the mean. All that evidence, and those +deductions, however, I must pass by for want of space, and take leave of +the subject. + + + + +Footnotes: + +[1] See the diagram for summer at page 55. + +[2] Law of Storms, p. 42. + +[3] Kearakakua Bay (called Cavrico above), is on the S. W. side of the +island, and the trade was reversed during the day by the cloud +condensation inland. + +[4] Lieutenant Wilkes spent twenty days upon the top of this or an +adjoining mountain, and his observations there will be alluded to in +another connection. + +[5] All attempts to produce this result by the sudden exhaustion of air +about the chickens in receivers, or shooting them from cannons, have +failed, and no patent for a chicken-picker has been applied for. + +[6] A meter is 1 yard, and .0936 of a yard. + +[7] See his map, accompanying the Geography of the Sea. + +[8] See Am. Jour. of Science, New Series, Vol. 18. p. 187. + +[9] Their estimate was 100 to 120 miles. + +[10] Since the text was in type, and, as might have been anticipated, we +have intelligence confirmatory of this, from the Cape De Verde Islands. +The inter-tropical belt of rains has not moved as far north as the +northern islands--they have had no rain--and the people are in a starving +condition. + + + + +Transcriber's Notes: + +Passages in italics are indicated by _italics_. + +Punctuation has been corrected without note. + +The following misprints have been corrected: + "appearnces" corrected to "appearances" (page 44) + "Faroday's" corrected to "Faraday's" (page 84) + "gentleman" corrected to "gentlemen" (page 96) + "two" corrected to "too" (page 105) + "surise" corrected to "sunrise" (page 111) + "acion" corrected to "action" (page 164) + "Stanta corrected to "Santa" (page 167) + "Augugst" corrected to "August" (page 167) + "baloon's" corrected to "balloon's" (page 192) + "mannner" corrected to "manner" (page 214) + "1198" corrected to "1798" (page 221) + "sevententh" corrected to "seventeenth" (page 240) + "maner" corrected to "manner" (page 254) + "particulary" corrected to "particularly" (page 256) + "are are" corrected to "are" (page 288) + "iso-theral" corrected to "iso-thermal" (page 299) + "the the" corrected to "the" (page 360) + "phenonema" corrected to "phenomena" (page 403) + "calorifice" corrected to "calorific" (page 409) + +Other than the corrections listed above, inconsistencies in spelling and +hyphenation have been retained from the original. + +Tables throughout this text version have been adjusted for readability. + + + + + + +End of the Project Gutenberg EBook of The Philosophy of the Weather, by +Thomas Belden Butler + +*** END OF THIS PROJECT GUTENBERG EBOOK THE PHILOSOPHY OF THE WEATHER *** + +***** This file should be named 33429-8.txt or 33429-8.zip ***** +This and all associated files of various formats will be found in: + http://www.gutenberg.org/3/3/4/2/33429/ + +Produced by Robin Monks and the Online Distributed +Proofreading Team at http://www.pgdp.net (This book was +produced from scanned images of public domain material +from the Google Print project and from The Internet Archive: +American Libraries.) + + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. 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You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: The Philosophy of the Weather + And a Guide to Its Changes + +Author: Thomas Belden Butler + +Release Date: August 14, 2010 [EBook #33429] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK THE PHILOSOPHY OF THE WEATHER *** + + + + +Produced by Robin Monks and the Online Distributed +Proofreading Team at http://www.pgdp.net (This book was +produced from scanned images of public domain material +from the Google Print project and from The Internet Archive: +American Libraries.) + + + + + + +</pre> + + + + +<h1>THE PHILOSOPHY</h1> +<h3>OF</h3> +<h1>THE WEATHER.</h1> +<h4>AND</h4> +<h2>A GUIDE TO ITS CHANGES.</h2> +<p> </p> +<h2>BY T. B. BUTLER.</h2> +<p> </p><p> </p> +<p class="center">NEW YORK:<br />D. APPLETON & COMPANY,<br />NOS. 346 & 348 BROADWAY.<br />1856.</p> +<p> </p><p> </p> +<p class="center">Entered according to Act of Congress, in the year 1856, by<br />T. B. BUTLER,<br /> +In the Clerks Office of the District Court of the District of Connecticut.</p> +<p> </p> +<p class="center">ELECTROTYPED BY<br />THOMAS B. SMITH,<br />82 & 84 Beekman Street.</p> +<p> </p> +<p class="center">PRINTED BY<br />J. F. TROW,<br />379 Broadway.</p> + + +<p> </p><p> </p> +<hr style="width: 50%;" /> +<p><span class="pagenum"><a name="Page_iii" id="Page_iii">[Pg iii]</a></span></p> +<h2>INTRODUCTION.</h2> + +<p>The atmospheric conditions and phenomena which constitute “The Weather” +are of surpassing interest. Now, we rejoice in the genial air and warm +rains of spring, which clothe the earth with verdure; in the alternating +heat and showers of summer, which insure the bountiful harvest; in the +milder, ripening sunshine of autumn; or the mantle of snow and the +invigorating air of a moderate winter’s-day. Now, again, we suffer from +drenching rains and, devastating floods, or excessive and debilitating +heat and parching drought, or sudden and unseasonable frost, or extreme +cold. And now, death and destruction come upon us or our property, at any +season, in the gale, the hurricane, or the tornado; or a succession of +sudden or peculiar changes blight our expected crops, and plant in our +systems the seeds of epidemic disease and death. These, and other normal +conditions, and varied changes, and violent extremes, potent for good or +evil, are continually alternating above and around us. They affect our +health and personal comfort, and, through those with whom we are +connected, our social and domestic enjoyments. They influence our business +prosperity directly, or indirectly, through our near or remote dependence +upon others. They limit our pleasures and amusements—they control the +realities of to-day, and the anticipations of to-morrow. None can +prudently disregard them; few can withhold from them a constant attention. +Scientific men, and others, devote to them daily hours of careful +observation<span class="pagenum"><a name="Page_iv" id="Page_iv">[Pg iv]</a></span> and registration. Devout Christians regard them as the +special agencies of an over-ruling Providence. The prudent, fear their +sudden, or silent and mysterious changes; the timid, their awful +manifestations of power; and they are, to each and all of us, ever present +objects of unfailing interest.</p> + +<p>This <i>interest</i> finds constant expression in our intercourse with each +other. A recent English writer has said: “The germ of meteorology is, as +it were, innate in the mind of every Englishman—the weather is his first +thought after every salutation.” In the qualified sense in which this was +probably intended, it is, doubtless, equally true of us. Indeed, it is +often not only a “first thought” <i>after</i> a salutation, but a part of the +salutation itself—an offspring of the same friendly feeling, or a part of +the same habit, which dictates the salutation—an expression of sympathy +in a subject of common and absorbing interest—a sorrowing or rejoicing +with those who sorrow or rejoice in the frowns and smiles of an +ever-changing, ever-influential atmosphere.</p> + +<p>If consistent with our purpose, it would be exceedingly interesting to +trace the varied forms of expression in use among different classes and +callings, and see how indicative they are of character and employment.</p> + +<p>The sailor deals mainly with the winds of the hour, and to him all the +other phases of the weather are comparatively indifferent. He speaks of +airs, and breezes, and squalls, and gales, and hurricanes; or of such +appearances of the sky as prognosticate them. The citizens, whose lives +are a succession of <i>days</i>, deal in such adjectives as characterize the +weather of <i>the day</i>, according to their class, or temperament, or +business; and it is pleasant, or fine, or <i>very</i> pleasant or fine; +beautiful, delightful, splendid, or glorious; or unpleasant, rainy, +stormy, dismal, dreadful or horrible. The farmer<span class="pagenum"><a name="Page_v" id="Page_v">[Pg v]</a></span> deals with the weather +of considerable periods; with forward or backward <i>seasons</i>, with “cold +snaps” or “hot spells,” and “wet spells” or “dry spells.” And there are +many intermediate varieties. The acute observer will find much in them to +instruct and amuse him, and will probably be surprised to find how much +they have to do with his “first impressions” of others.</p> + +<p>But I have a more important object in view. I propose to deal with “The +<span class="smcap">Philosophy</span> <i>of the Weather</i>”—to examine the nature and operation of the +arrangements from which the phenomena result; to strip the subject, if +possible, of some of the complication and mystery in which traditionary +axioms and false theories continue to envelop it; to endeavor to grasp +<i>its principles</i>, and unfold them in a plain, concise, and systematic +manner, to the comprehension of “<i>the many</i>,” who are equal partners with +the scientific in its practical, if not in its philosophic interest; and +to deduce a few general rules by which its changes may be understood, and, +ultimately, to a considerable extent, foreseen.</p> + +<p>This is not an easy, perhaps not a prudent undertaking. Nor is my position +exactly that of a volunteer. A few words seem necessary, therefore, by way +of apology and explanation.</p> + +<p>In the fall of 1853, in the evening of a fair autumnal day, I started for +Hartford, in the express train. Just above Meriden, an acquaintance +sitting beside me, who had been felicitating himself on the prospect of +fine weather for a journey to the north, called my attention to several +small patches of scud—clouds he called them—to the eastward of us, +between us and the full clear moon, which seemed to be enlarging and +traveling south—and asked what they meant.</p> + +<p>“Ah!” said I, “they are scud, forming over the central and northern +portions of Connecticut, induced and attracted by<span class="pagenum"><a name="Page_vi" id="Page_vi">[Pg vi]</a></span> the influence of a +storm which is passing from the westward to the eastward, over the +northern parts of New England, and are traveling toward it in a southerly +surface wind, which we have run into. They seem to go south, because we +are running north faster than they. You see them at the eastward because +they are forming successively as the storm and its influence passes in +that direction, and are most readily seen in the range of the moon; but +when we reach Hartford you will see them in every direction, more numerous +and dense, running north to underlie that storm.”</p> + +<p>I had seen such appearances too many times to be deceived. It was so. When +we arrived at Hartford they were visible in all directions, running to the +northward at the rate of twenty-five miles an hour. In the space of forty +minutes we had passed from a clear, calm atmosphere (and which still +remained so), into a cloudy, damp air, and brisk wind blowing in the same +direction we were traveling, and toward a heavy storm. My friend passed +on, and met the southern edge of the rain at Deerfield, and had a most +unpleasant journey during the forenoon of the next day. Taking the cars +soon afterwards, in the afternoon, for the south, I found him on his +return.</p> + +<p>“Shall I have fair weather now till I get home?” said he.</p> + +<p>“There are no indications of a storm here, or at present,” I replied, “but +we may observe them elsewhere, and at nightfall.”</p> + +<p>He kept a sharp look-out, and, as we neared New Haven, discovered faint +lines of cirrus cloud low down in the west, extending in parallel bars, +contracting into threads, up from the western horizon, in an E. N. E. +direction toward the zenith.</p> + +<p>“Now, what is that?” said he.</p> + +<p>“The eastern outlying edge of a N. E. storm, approaching from the W. S. W. +It is now raining from 150 to 200 miles to the westward of the eastern +extremity of those bars<span class="pagenum"><a name="Page_vii" id="Page_vii">[Pg vii]</a></span> of cirrus-condensation; perhaps more, perhaps +less; and under those bars of condensation the wind is attracted, and is +blowing from the N. E. toward the body of the storm, and where the +condensation is sufficiently dense to drop rain. That dense portion will +reach here, and it will rain from twelve to fifteen hours hence. As we +pass along the shore, and run under that out-lying advance +cirrus-condensation, we shall see that the vessels in the Sound have the +wind from the N. E., freshening, but we shall continue to have this light +and scarcely-perceptible air from the northward for a time—<i>the N. E. +wind always setting in toward an approaching storm, out on the Sound, much +sooner than upon the land</i>.”</p> + +<p>As we approached the storm, and the storm us, the evidence of denser +condensation at the west, and of wind from the east, blowing toward it, +became more apparent. The fore and aft vessels were running “up Sound” +with “sheet out and boom off,” before a fresh N. E. breeze, and my friend +was astonished.</p> + +<p>“I must understand this,” said he; “how is it?”</p> + +<p>“All very simple. The page of nature spread out above us is intelligible +to him who will attentively study it. The laws which produce the +impressions and changes upon that page, are few and comprehensible. +Although there is great variety, even upon the limited portion which is +bounded by our horizon, there is also substantial uniformity; and, +although the changes are always extensive, often covering an area of one +thousand miles or more, and our vision can not extend in any direction +more than from thirty to fifty, yet those changes are always, to a +considerable extent, intelligible, and may often be foreseen.”</p> + +<p>“Has meteorology made such progress?”</p> + +<p>“By no means. It has, indeed, been raised to the dignity of a science, and +professorships endowed for its advancement.<span class="pagenum"><a name="Page_viii" id="Page_viii">[Pg viii]</a></span> Some books have been written, +and many theories broached in relation to it; and innumerable observations +of the states of the barometer and thermometer, of the clouds, and the +quantity of fallen rain, and the direction and force of the wind—made and +recorded simultaneously in different countries—have been published and +compared; and a great many important facts established, and tables of +‘<i>means</i>’ constructed, and just inferences drawn, yet the <i>few and simple +arrangements</i> upon which all the phenomena depend, and <i>their philosophy</i>, +have not yet been clearly elicited or understood.”</p> + +<p>“Have not the ‘American Association for the Advancement of Science’ +arrived at some definite and sound conclusion upon the subject?”</p> + +<p>“No; it has been with them, for many years, an interesting subject for +papers and debate. Some very valuable articles, upon particular topics, or +branches of the subject, have been read and published. But the +<i>Cyclonologists</i>, as they term themselves, and who seem to think the great +question is, ‘<i>Are storms whirlwinds?</i>’ appear with new editions and +phases of their favorite views as regularly as the annual meeting recurs; +and, though they have not convinced, they seem to have silenced their +opponents. The only conclusion, however, judging from their debates, to +which the Association appear to have come with any considerable unanimity, +is, that they are yet without sufficient <i>authentic observations</i> and +well-established facts, to authorize the adoption of the Huttonian, +Daltonian, Gyratory, or Aspiratory, or any of the other numerous theories +which abound. And they are right. The subject is mystified by these +theories and speculations of the study, founded on barometrical and +thermometrical records, and the direction and force of the surface winds.</p> + +<p>“The qualities of heat were among the earlier discoveries of science, and +all the phenomena of the weather were forthwith<span class="pagenum"><a name="Page_ix" id="Page_ix">[Pg ix]</a></span> attributed to its +influence. Hastily-formed and erroneous views of its power, and the manner +of its action in particular localities, and under particular +circumstances, have retained the credence accorded to them when first +announced, although subsequent discoveries have shown their fallacy; some +new theory of <i>modification</i> having been invented to reconcile the +discrepancies as soon as they appeared. Perhaps it is not too much to say +(however it may seem to one not thoroughly acquainted with the subject, +who does not know that the <i>primary</i> and secondary modifying hypotheses +found in Kämtz, may be counted by hundreds) that there is not remaining in +any other science, and possibly in all others, an equal amount of false +and absurd theory, and of forced and unnatural grouping of admitted facts +to sustain it, as in meteorology as at present taught and received. +Astronomy, as a science, is almost perfected—the nature, and size, and +orbits, of the distant worlds around us are known—while constant changes +and alternating atmospheric conditions, which all occur <i>within less than +six miles of us</i>, affecting all our important interests, and obvious to +our senses, although much talked off, and made the objects of many +theories, are but little understood.”</p> + +<p>“How, then, did you acquire the information you seem to possess?”</p> + +<p>“By studying ‘<i>the countenance of the sky</i>,’ for in no other way has such +information ever been, or can it ever be, acquired. By a long-continued, +daily, and sometimes hourly observation of the clouds and currents of the +atmosphere, in connection with such reports of the then state of the +weather elsewhere, as have fallen under my notice, and the effect of its +changes upon the animal creation—for very much can be learned from them. +Yonder flock of black ducks that sit on that inshore rock, above the +tide—the wildest and<span class="pagenum"><a name="Page_x" id="Page_x">[Pg x]</a></span> most suspicious of all their tribe—although the +air is calm about them, know well that a storm is at hand. They probably +both see and feel it. As twilight approaches they will fly away inland, +forty or fifty miles perhaps, and settle among the lilies or grass which +surround some fresh-water pond, certain of remaining while the storm +lasts, and for one day at least, out of danger, and undisturbed. Many a +time, in my boyhood, have I heard, in the stillness of evening, the +whistling of their wings, as they swept up the Connecticut valley, to +seek, on the borders of the coves, and in the creeks of the meadows, a +concealed and safe feeding-place during a coming storm. And many a time in +the autumn, after they had all passed down for the season, when the +indications of an approaching storm were clearly visible at nightfall, +have I waited for them to return, on the eastern margin of a bend in the +cove, on the eastern side of a creek, to shoot them, though invisible, by +shooting across the head of the wake, which they made upon the water in +alighting, and from which the few remaining rays of twilight that came +from the western sky were reflected.</p> + +<p>“But I am far from being singular in this. That page is more extensively +read than is generally supposed. Many plain, unassuming men—farmers, +shipmasters, and others within the circle of my acquaintance—know more, +practically, of the weather than the most learned closet-theorist, or the +most indefatigable recorder of its changes. Every one, by studying the +page of nature above him, as he would the page of any other science, and +testing, by observation, the numerous theories invented to account for the +varied phenomena, may learn much, very much, that will be useful and +interesting to him, and which he can never learn from books, or +instruments, or theories alone.”</p> + +<p>“Well,” said my friend, “I am too far advanced in life, as<span class="pagenum"><a name="Page_xi" id="Page_xi">[Pg xi]</a></span> are many +others, to commence such observations, and you must publish.”</p> + +<p>I demurred, and he insisted.</p> + +<p>“It is difficult to spare the time; and I can not neglect my profession,” I urged.</p> + +<p>“Where there is a will there is a way,” he replied.</p> + +<p>“It is difficult to make one’s self understood without many illustrations.”</p> + +<p>“Very well, they are easily obtained.”</p> + +<p>“But they cost money, and it is said ‘science will not pay its way’ like fiction and humbug.”</p> + +<p>“That,” said he, “is a libel—such science will. Every one is interested +in the weather—all talk about it—and thousands would carefully observe +it, if they could be correctly guided in their observations.”</p> + +<p>“I may get into unpleasant controversy.”</p> + +<p>“Suppose you do; you can yield your position if wrong, and maintain it if +right, and <i>magna est veritas</i>.”</p> + +<p>“But I may be mistaken in some of the views to which it will be necessary +to advert, if I attempt to systematize the subject.”</p> + +<p>“Be it so—your mistakes may lead others to the discovery of the truth. +Besides, the weather is <i>common property</i>, and every one has a right to +theorize about it, or to talk about it, as they please—even to call a +stormy day a pleasant one, or make any other mistaken remark concerning +it; and every other person is entitled to a like latitude of reply. And +further,” said he, with some emphasis, “no important observation, in +relation to a subject of such interest, should be lost; and, if you have +observed one new fact, or drawn one new and just inference from those +which have been observed by others; and especially if, from observation +and reading, you can deduce from the phenomena an intelligible,<span class="pagenum"><a name="Page_xii" id="Page_xii">[Pg xii]</a></span> +<i>observable, general system</i>, it is not only your right, but duty, to make +it known. Such a knowledge of the true system is greatly desired by every +considerate man.”</p> + +<p>To my friend’s last argument I was compelled to yield. I could make no +reply consistent with the great principles of fraternity, which I shall +ever recognize. The promise was given. My friend went on his way, and I +went to the daguerreotypist to procure a copy of the then appearance of +the sky, as the first step toward its fulfillment. The fulfillment of that +promise, reader, you will find in the following work. It was commenced as +an article for a magazine, but it has grown on my hands to a volume. +Justice could not well be done to the subject in less space. It has been +written during occasional and distant intervals of relaxation from +professional avocations, or during convalescence from sickness, and it is, +for these reasons, somewhat imperfect in style and arrangement. But I have +no time to rewrite. There is much in it which will be old to those who +read journals of science, but new to those who do not. There is more which +will be new to all classes of readers, and may, perhaps, be deemed +heretical and revolutionary by conservative meteorologists; yet I feel +assured that the work is a step in the right direction—that it contains a +substantially accurate exposition of the Philosophy of the Weather, and +valuable suggestions for the practical observer.</p> + +<p>I have inserted my name in the title-page, contrary to my original +intention, and at the suggestion of others; for I have no scientific +reputation which will aid the publisher to sell a copy. Nor do I desire to +acquire such reputation. It can never form any part of my “capital in +life.” Nor has it influenced me at all in preparing the work. I have aimed +to fulfill a promise, too hastily given, perhaps—to put on record the +observations I have made, and the inferences I have drawn from those of +others—to induce and assist further <span class="pagenum"><a name="Page_xiii" id="Page_xiii">[Pg xiii]</a></span>observations, and, if possible, of a +<i>general</i> and <i>connected character</i>—and to impress those who may read +what I have written with the belief, that <i>they will derive a degree of +pleasure from a daily familiarity with, and intelligent understanding of, +the “countenance of the sky,” not exceeded by that which any other science +can afford them</i>.</p> + +<p>I have examined, with entire freedom and fearlessness (but I trust in a +manner which will not be deemed censurable or in bad taste) the theories +and supposed erroneous views of others, for, in my judgment, the +advancement of the science requires it. Says Sir George Harvey, in his +able article on Meteorology, written for the Encyclopædia Metropolitana:</p> + +<div class="blockquot"><p>“It is humiliating to those who have been most occupied in +cultivating the science of meteorology, to see an agriculturist or a +waterman, who has neither instruments nor theory, foretell the future +changes of the weather many days before they happen, with a precision +which the philosopher, aided by all the resources of science, would +be unable to attain.”</p></div> + +<p>The admissions contained in this paragraph, in relation to the comparative +uselessness of instruments and theories, and the value of practical +observation, are both in a good measure true. And the time has come, or +should speedily come, when “<i>pride of opinion</i>,” and “<i>esprit du corps</i>,” +among theorists and philosophers, should neither be indulged in, nor +respected; and when their theories should be freely discussed, and rigidly +tested by the observations of practical men. Such measure, therefore, as I +have meted, I invite in return. Let whatever I have advanced, that is new, +or adopted that is old, be <i>as</i> rigidly tested, and <i>as</i> freely discussed. +Let the errors, if there be any—and doubtless there are—be detected and +exposed. Let the <span class="smcaplc">TRUTH</span> be sought by all; and meteorology, as a <span class="smcaplc">PRACTICAL +SCIENCE</span>, advance to that full measure of perfection and usefulness, of +which it is unquestionably susceptible.</p> + +<p><span class="pagenum"><a name="Page_xiv" id="Page_xiv">[Pg xiv]</a></span></p> + +<p> </p><p> </p> +<hr style="width: 50%;" /> +<p><span class="pagenum"><a name="Page_xv" id="Page_xv">[Pg xv]</a></span></p> +<h2>TABLE OF CONTENTS.</h2> + +<table width="80%" border="0" cellpadding="0" cellspacing="5" summary="contents"> +<tr><td> </td><td align="right"><small>PAGE</small></td></tr> +<tr><td align="center"><a href="#CHAPTER_I">CHAPTER I.</a></td></tr> +<tr><td>Heat and moisture are indispensable to the fertillity of the +earth—Arrangements exist for their diffusion and distribution, +and all the phenomena of the weather result from their +operation—Heat furnished or produced mainly by the direct +action of the sun’s rays—Manner in which it is diffused over +the earth—Other causes operate besides the sun’s rays—The +earth intensely heated in its interior—Heat derived from the +great Oceanic currents, and the aerial currents which flow +from the tropics to the poles, and from magnetism and electricity—Water +distributed by an atmospheric machinery as extensive +as the globe—Evidences of this—Its distribution over +the continents of North America—Explanation of it—Source +from whence our supply of water is derived, and from which our rivers return</td><td valign="bottom" align="right"><a href="#Page_1">1</a></td></tr> +<tr><td> </td></tr> +<tr><td align="center"><a href="#CHAPTER_II">CHAPTER II.</a></td></tr> +<tr><td>Our rivers return in the form of clouds, and in storms and +showers—Definition and character of storms—Differences in +the character of the clouds which constitute them—Nomenclature +of Howard—Its imperfections—New order of description—Low +fog—High fog—Storm fog—Storm scud—N. W. scud—Cumulus—Stratus—Cirrus—Compounds +of the two latter—recapitulation in tabular form</td><td valign="bottom" align="right"><a href="#Page_24">24</a></td></tr> +<tr><td> </td></tr> +<tr><td align="center"><a href="#CHAPTER_III">CHAPTER III.</a></td></tr> +<tr><td>Our rivers do not return from the North Atlantic—All storms +<span class="pagenum"><a name="Page_xvi" id="Page_xvi">[Pg xvi]</a></span>and showers +move from the westward to the eastward—Seeming clouds seen moving from the eastward to the westward +are scud—They are incidents of the storm, and not a necessary +part of it—The storm clouds are above them, moving to +the eastward—Occasions when this may be seen—Admitted +facts prove it—Investigations prove it—May be known from +analogy—From the fact that there is an aerial current pursuing +the same course in which the storms originate—Character of +this current—Its influence upon our country—Importance +of a knowledge of its origin, cause, and the reciprocal action +between it and the earth—To this end necessary to go down +“to the chambers of the South”</td><td valign="bottom" align="right"><a href="#Page_43">43</a></td></tr> +<tr><td> </td></tr> +<tr><td align="center"><a href="#CHAPTER_IV">CHAPTER IV.</a></td></tr> +<tr><td>The trade wind region—Its extent and arrangements—Its belt +of daily rains and movable character—The trade winds—The +extra tropical belt of rains—Connection between them +and their annual movements—The counter-trades—Their origin +and situation—One of them constitutes our aerial current—It +originates in the South Atlantic as a surface-trade—Anomalies +of the trade wind region—Dry seasons—Humboldt’s description +of them—Exist where the surface trades are situated—The +rainless countries—Concentrated counter-trade—Monsoons—Received +theory in relation to them a fallacy—Cause +of the great central phenomena—Calorific theory a fallacy—Land +not hotter under the belt of rains, nor sea materially +so—Theory should be abandoned</td><td valign="bottom" align="right"><a href="#Page_52">52</a></td></tr> +<tr><td> </td></tr> +<tr><td align="center"><a href="#CHAPTER_V">CHAPTER V.</a></td></tr> +<tr><td>The agent, magnetism—Its character and currents—Oxygen +magnetic—Precipitation at the belt of rains occasioned by depolarization—Storms +originate in this central belt, and move toward the poles</td><td valign="bottom" align="right"><a href="#Page_82">82</a></td></tr> +<tr><td> </td></tr> +<tr><td align="center"><a href="#CHAPTER_VI">CHAPTER VI.</a></td></tr> +<tr><td>Course and functions of the counter-trade—Ours come from the +South Atlantic—Reason why it can not come from the +<span class="pagenum"><a name="Page_xvii" id="Page_xvii">[Pg xvii]</a></span>Pacific—Mistake of Mr. Redfield and Lieutenant Maury in +regard to it—All our storms originate in it—Proofs of this—State +of the weather, whether hot or cold affected by it—Proofs +of this—All our surface winds are incidents of it, and +due to its conditions and attractions—Proofs of this—Character +of the different winds—Anomalies of Mr. Blodgett accounted +for—Received theory in regard to sea and land +breezes a mistaken one—Proofs of this—Peculiar character +of the N. W. wind—Identity with the winter Mexican northers—Character +of the West India hurricanes—Of the thunder-gust—Of +the tornado—Sundry particulars in relation to the +latter—Due to currents of electricity—Proportions of winds +in different localities—Examination of the work of Professor +Coffin upon that subject—Examination of Lieutenant Maury’s theory of the monsoons</td><td valign="bottom" align="right"><a href="#Page_92">92</a></td></tr> +<tr><td> </td></tr> +<tr><td align="center"><a href="#CHAPTER_VII">CHAPTER VII.</a></td></tr> +<tr><td>Height of the counter-trade in different latitudes—Cause of the +Calms of Cancer—Influence of mountains upon the counter-trade—Reports +of Herndon and Gibbon—Focus of precipitation +in the extra-tropical belt north of its southern line—Evidences +of this—The elevation of the counter-trade above the +earth varies in the same latitude with the variations in the phenomena +of the weather—Temperature of the counter-trade—Rain +dust, its origin and indications—Volcanic ashes—How +far they indicate its course of progression—Question whether +there is an eastern progression of the body of the atmosphere above the machinery of distribution</td><td valign="bottom" align="right"><a href="#Page_179">179</a></td></tr> +<tr><td> </td></tr> +<tr><td align="center"><a href="#CHAPTER_VIII">CHAPTER VIII.</a></td></tr> +<tr><td>Important to understand the precise character of the reciprocal +action between the earth and the counter-trade—Connection +between the width and movements of the belt of inter-tropical +rains and the volume of the trades—Its peculiarities +over Africa, the Atlantic, and South America—The magnetic +equator—Character of the storms which originate in the inter-tropical +belt indicate local magnetic action—Supposed influence +of volcanic action—Gulf Stream changes its position—This +the result of magnetic action—Alternating contrasts of +<span class="pagenum"><a name="Page_xviii" id="Page_xviii">[Pg xviii]</a></span>heat and cold, and rain and drought—Dr. Webster’s history of +the weather—Spots upon the sun—Their character and influence—Cold +or warm periods during the same decade, and +during different decades—Connection between the spots and +magnetic disturbances and variations—Influence of the moon +upon the weather—No decisive inference to be drawn from +these facts, and a more critical examination necessary</td><td valign="bottom" align="right"><a href="#Page_204">204</a></td></tr> +<tr><td> </td></tr> +<tr><td align="center"><a href="#CHAPTER_IX">CHAPTER IX.</a></td></tr> +<tr><td>Examination of existing theories—Calorific theory the prevailing +one—Lateral overflow of Professor Dove—Absurdity of his +views in relation to them—His theory of hurricanes—Its absurdity—A +new theory by Mr. Dobson—Three theories advanced +by meteorologists of this country—Professor Espy’s +theory—Mr. Bassnett’s theory—Mr. Redfield’s theory—Extended +examination of the latter—His theory in relation to +the fall of the barometer contradictory in its character—Philosophy +of the barometric change—No aid to be derived from these theories</td><td valign="bottom" align="right"><a href="#Page_232">232</a></td></tr> +<tr><td> </td></tr> +<tr><td align="center"><a href="#CHAPTER_X">CHAPTER X.</a></td></tr> +<tr><td>Further inquiry in relation to the reciprocal action between the +earth and the counter-trade—Terrestrial magnetism, and what +we know of it—Its elements, and their variations—Their connection +with the variations of atmospheric condition—Magnetism +acts through its connection with electricity—Character +of the latter and its variations—Their connection with atmospheric +conditions—Electricity as well as magnetism in excess +over this country—Effects of it upon our climate—Closer consideration +of the atmospheric phenomena—Their diurnal +changes and connections compared with those of magnetism +and electricity—Grouping of all the diurnal variations—Particular +and separate examination of them—Classification of +storms—Examination in detail of the several classes and the +primary influence of the earth or counter-trade in relation to each</td><td valign="bottom" align="right"><a href="#Page_285">285</a></td></tr> +<tr><td> </td></tr> +<tr><td align="center"><a href="#CHAPTER_XI">CHAPTER XI.</a></td></tr> +<tr><td>Prognostics</td><td align="right"><a href="#Page_340">340</a></td></tr></table> + + +<p> </p><p> </p> +<hr style="width: 50%;" /> +<p><span class="pagenum"><a name="Page_1" id="Page_1">[Pg 1]</a></span></p> +<h1>THE PHILOSOPHY OF THE WEATHER.</h1> +<p> </p> +<h2><a name="CHAPTER_I" id="CHAPTER_I"></a>CHAPTER I.</h2> + +<p>Heat and moisture are indispensable to the fertility of the earth. Without +suitable arrangements for their diffusion and distribution, and within the +limits of certain minima and maxima, it would not have been habitable, or +the design of its Creator perfected. These arrangements therefore exist, +and “while the earth remaineth seed time and harvest shall not cease.” Few +and simple in their character, though necessarily somewhat complicated and +irregular in their operation, the ultimate result is always attained. A +beautiful system of compensations supplies the losses of every apparent +irregularity in one section or crop, by the abundance of others.</p> + +<p>From the operation of these few, simple, connected, and intelligible +arrangements for the diffusion of heat and the distribution of moisture +over the earth, result all the phenomena which constitute the weather; and +by studying them, and their<span class="pagenum"><a name="Page_2" id="Page_2">[Pg 2]</a></span> operation, we may acquire an accurate +knowledge of its “<i>Philosophy</i>.”</p> + +<p>The necessary heat is furnished, or produced, mainly by the direct action +of the sun’s rays; and the most obvious feature in the arrangements for +its diffusion is that by which the sun is made to shine successively and +alternately upon different portions of the earth. Nothing animate or +organic could endure his burning rays, if they shone continuously or +vertically upon one point, or could exist without their occasional +presence. Hence the provision for a diurnal rotation, to prevent the +exposure of any portion of the globe to the action of those rays for +twenty-four consecutive hours, except for a limited period, and at a +considerable angle, in the polar regions. But the earth is spheroidal, and +a diurnal revolution would still leave that portion which lies under the +equator too much, and the other too little, exposed to the action of the +sun. This is obviated by an annual revolution of the earth around the sun, +and an obliquity of its axis, by reason of which the northern and southern +portions are alternately and, as far as the tropics vertically, exposed to +the sun; and it is made to travel (so to speak) from tropic to tropic, +producing summer and winter, and other important phenomena.</p> + +<p>This obliquity and consequent change of exposure are in degree precisely +what the wants of the earth would seem to require. If it was greater, the +sun would travel further north and south, but the alternate winters would +be longer and more severe. If<span class="pagenum"><a name="Page_3" id="Page_3">[Pg 3]</a></span> it was less, the end would not be as +perfectly attained.</p> + +<p>The direct action of the sun’s rays upon the earth, particularly those +portions which lie north and south of the tropics, is not the only source +from which the supply of heat is derived. Although there is a general +increase of heat in spring and summer when the sun travels north, and of +cold when he travels south in winter, yet there are frequent +irregularities attending both. Very sudden and great changes occur in each +of them. Frost sometimes, cool weather often, occurs in midsummer, and +considerable heat and tornadoes in midwinter. And ordinarily the maxima +and minima of each month and, indeed, of each week are widely apart. Even +in the polar regions, in midwinter, <i>where the sun does not shine at all</i>, +the same moderating changes with which we are conversant occur in degree. +An extract or two from the register found in Dr. Kane’s narrative of the +“Grinnell Expedition” will illustrate this.</p> + +<p class="center"><span class="smcap">January 1851, (Latitude about 74°, Longitude about 70°).</span></p> + +<table border="0" cellpadding="0" cellspacing="0" summary="January"> +<tr><td class="btl" align="center">Date.</td> + <td class="btl" align="center">Wind.</td> + <td class="btl" align="center">Force.</td> + <td class="btl" align="center">Ther.</td> + <td class="btl" align="center">Bar.</td> + <td class="btrl" align="center">Sky and Weather.</td></tr> +<tr><td class="btl">Jan. 3</td> + <td class="btl">......</td> + <td class="btl">calm</td> + <td class="btl">-26.1</td> + <td class="btl">29.62</td> + <td class="btrl">blue sky, m.</td></tr> +<tr><td class="bl"><span style="margin-left: .5em;">"</span><span style="margin-left: 1em;">4</span></td> + <td class="bl">W.</td> + <td class="bl">gent breeze</td> + <td class="bl">-21.3</td> + <td class="bl">29.53</td> + <td class="blr">blue sky, detached clouds, m.</td></tr> +<tr><td class="bl"><span style="margin-left: .5em;">"</span><span style="margin-left: 1em;">5</span></td> + <td class="bl">W. by N.</td> + <td class="bl">gent breeze</td> + <td class="bl">-3.9</td> + <td class="bl">29.59</td> + <td class="blr">blue sky, m., clouded over.</td></tr> +<tr><td class="bl"><span style="margin-left: .5em;">"</span><span style="margin-left: 1em;">6</span></td> + <td class="bl">W. by S.</td> + <td class="bl">light breeze</td> + <td class="bl">-0.8</td> + <td class="bl">29.67</td> + <td class="blr">clouded over, m., snow.</td></tr> +<tr><td class="bl"><span style="margin-left: .5em;">"</span><span style="margin-left: 1em;">7</span></td> + <td class="bl">W.</td> + <td class="bl">gent breeze</td> + <td class="bl">-14.4</td> + <td class="bl">29.96</td> + <td class="blr">blue sky, detached clouds, m.</td></tr> +<tr><td class="bl"><span style="margin-left: .5em;">"</span><span style="margin-left: 1em;">8</span></td> + <td class="bl">W.S.W.</td> + <td class="bl">light air</td> + <td class="bl">-21.2</td> + <td class="bl">30.14</td> + <td class="blr">blue sky, m.</td></tr> +<tr><td class="bl"><span style="margin-left: .5em;">"</span><span style="margin-left: .5em;">29</span></td> + <td class="bl">W.N.W.</td> + <td class="bl">light air</td> + <td class="bl">-18.9</td> + <td class="bl">30.19</td> + <td class="blr">blue sky.</td></tr> +<tr><td class="bl"><span style="margin-left: .5em;">"</span><span style="margin-left: .5em;">30</span></td> + <td class="bl">NW. by W.</td> + <td class="bl">light air</td> + <td class="bl">-13.5</td> + <td class="bl">30.17</td> + <td class="blr">clouded over, m.</td></tr> +<tr><td class="bl"><span style="margin-left: .5em;">"</span><span style="margin-left: .5em;">31</span></td> + <td class="bl">NW. by W.</td> + <td class="bl">gent breeze</td> + <td class="bl">-4.4</td> + <td class="bl">29.35</td> + <td class="blr">clouded over, snow.</td></tr> +<tr><td class="bl">Feb. 1</td> + <td class="bl">W.</td> + <td class="bl">light breeze</td> + <td class="bl">-11.7</td> + <td class="bl">29.27</td> + <td class="blr">cloudy, blue sky, m.</td></tr> +<tr><td class="bbl"><span style="margin-left: .5em;">"</span><span style="margin-left: 1.25em;">2</span></td> + <td class="bbl">W.</td> + <td class="bbl">light air</td> + <td class="bbl">-25.1</td> + <td class="bbl">29.62</td> + <td class="bblr">blue sky, detached clouds, m.</td></tr></table> + + +<p>These extracts are instructive. It will be seen<span class="pagenum"><a name="Page_4" id="Page_4">[Pg 4]</a></span> that on the 3d of +January, when the sun had been absent some weeks, it was calm, the +thermometer stood at 26° below zero (the - or minus mark before the +figures indicates that), and the barometer at 29.62, with blue sky, +somewhat misty or hazy—(the letter “m.” standing for misty or hazy)—a +state of the air which existed most of the time when it did not snow or +rain, and therefore is of no importance in this connection. The next day +the thermometer began to rise, and the barometer to fall. On the 5th it +clouded over, and the thermometer rose rapidly, and on the 6th it had +risen more than 25°, and snow fell. On the 7th it cleared off, the +thermometer fell rapidly, and the barometer rose. On the 8th the +thermometer had fallen to 21° below zero, and the barometer had risen to +30.14. Another instance, in all respects similar, occurred the latter part +of the month. We shall see hereafter that these changes are precisely like +those which occur with us, and every where. That, as in the polar regions, +and whether the sun be present or absent, or obscured by clouds, and by +night as well as by day, the changes from warm to cold and from cold to +warm are sudden and great, and that the latter are connected with the fall +of rain and snow—that every where in winter it <i>moderates to storm</i>.</p> + +<p>Many other instructive instances, especially in relation to the great +difference in the seasons in our own country, and upon the same parallels +elsewhere, might be cited if it were necessary. But they will more +appropriately appear in the sequel.</p> + +<p><span class="pagenum"><a name="Page_5" id="Page_5">[Pg 5]</a></span></p> +<p> </p> +<p><span class="pagenum"><a name="Page_6" id="Page_6">[Pg 6]</a></span></p> + +<p class="center"><strong>Fig. 1.</strong></p> +<div class="figcenter"><img src="images/i0027.jpg" alt="" /></div> +<p class="note">In the above cut the isothermal lines are Centigrade. The zero of the +Centigrade thermometer is the freezing point of water, or 32° of +Fahrenheit. The boiling point of water is 100° Centigrade, or 212° +Fahrenheit. A degree of Centigrade is equal to one degree and four-fifths, +Fahrenheit. The 0° line of the cut, therefore, is 32° of Fahrenheit—the +line of 5° above is 41° Fahrenheit—the line of 5° below is 23° +Fahrenheit, and so on. The reader, who is not familiar with the difference +in the scale of the thermometer, is desired to remember this; for we shall +make occasional extracts in which the temperature is given in the Centigrade scale.</p> +<p> </p> + +<p><span class="pagenum"><a name="Page_7" id="Page_7">[Pg 7]</a></span>The cause of those irregularities, especially in the same seasons of +different years, and when very great, is often sought and supposed to be +found in the presence or absence of spots on the sun, ice floes and bergs +in the Atlantic, etc., etc. But neither the spots, nor ice, nor other +local causes produce them. The cause will be found in the character of the +arrangements we are considering, and the irregular action of the power +which controls them.</p> + +<p>Nor is the temperature of the northern hemisphere, north of the tropics, +equal in the same latitudes. Very great diversities exist in the “annual +mean” as well as the “mean” of the different seasons. Accurate +observations at many points have enabled men of science to demonstrate +this by drawing isothermal lines (<i>i. e.</i>, lines of equal average annual +heat) from point to point around the earth, which show at a glance these +differences. The annexed cut is a polar projection of the isothermal lines +of the northern hemisphere, as far down as the tropic, copied from +Kaemtz’s Meteorology. The dotted lines show the parallels of latitude, the +dark lines the isothermal lines, or lines of equal annual average +temperature. The reader is desired to observe how rarely they correspond +with the parallels of latitude, and how they fall below in a few +instances, and in others with great uniformity rise almost to the pole.</p> + +<p>Take, for example, the isothermal line of 0 or zero—that is, the line +where the mean or <i>average</i> height of the thermometer <i>for the year</i> is at +zero. At Behring’s Straits this line is a little below the<span class="pagenum"><a name="Page_8" id="Page_8">[Pg 8]</a></span> Arctic circle, +or the parallel of 66.30 north latitude. Passing east over North America, +it descends into Canada, almost to Lake Superior, and to about the 50th +parallel: that is to say, it is on an average during the year as cold on +our continent at the 50th parallel as it is near Behring’s Straits at the +65th parallel. Passing east, the line of zero rises again over the +Atlantic Ocean until, in the meridian of Spitzbergen, it reaches, within +the Arctic circle, up almost to the 75th parallel. So, too, the isothermal +of 5° below zero, which is below the 60th parallel in Siberia, rises in +the North Sea, above Behring’s Straits, to the parallel of 75°, descending +on the continent in North America to the 55th parallel, and rising again +almost to the pole at Spitzbergen, to descend again in Siberia, while the +isothermals of 10° and 15° below zero, which in North America are but just +above the latitude of 60° and 75° respectively, ascend abruptly +<i>surrounding the magnetic pole</i>, and <i>falling short of the geographical +one</i>. Let this projection of the lines of equal temperature, and +particularly the situation of the magnetic poles, be studied well, for we +shall recur to it hereafter in illustration of many important portions of +our subject.</p> + +<p>It is apparent from these facts, and were it necessary might be rendered +still more so by referring to others, that other causes operate in the +distribution of heat over the earth besides the direct action of the sun’s +rays upon it. Doubtless very considerable allowance is to be made for the +difference of seasons, and difference during the same season upon the +land<span class="pagenum"><a name="Page_9" id="Page_9">[Pg 9]</a></span> and upon the ocean; in mountainous countries and level ones. But +making every allowance for them, the fact that other causes have a +<i>controlling</i> influence in producing the deviations still remains most +obvious. Neither the difference of temperature between the land and the +ocean, or land surfaces of unequal elevations, will account for the +elevation of the isothermal lines on different portions of the ocean, or +their extension around the magnetic poles.</p> + +<p>Returning to a consideration of the arrangements for the diffusion of +heat, we observe: First, that the earth itself is intensely heated in its +interior. This is inferred, and justly, from the fact that the thermometer +is found to rise about one degree for every fifty-five feet of +descent—whether in boring artesian wells, exploring caves, or sinking +shafts in mines. It is demonstrated, also, by the existence of hot springs +and the action of volcanoes. Heat is supposed to be conducted from the +center toward the surface every where, but with difficulty and slowly. It +is also supposed to be conducted from the tropical regions toward the +poles. Such is the opinion of Humboldt. (Cosmos, vol. i. p. 167.)</p> + +<p>Probably it reaches the surface and exerts an influence, also, upon the +weather through the ocean, and by heating it in its greatest depths. +Little attention has been paid, so far as I am informed, to the question +how far the ocean is thus heated in <i>tropical latitudes</i>. Doubtless a +portion of the warmth of the ocean there is derived from that source, and +it has its influence in changing the temperature of the <span class="pagenum"><a name="Page_10" id="Page_10">[Pg 10]</a></span>deep-seated cold +polar currents of, the great oceans. Perhaps it may yet be found that the +icebergs are detached by it in the polar seas—the observations of Dr. +Kane point to such a result. (Grinnell Expedition, p. 113, and also chap. +48.)</p> + +<p>Little need be said of the inconsiderable quantities of heat supposed to +be derived by radiation from the stars, the planets, and from space. If +any such are derived they are too inconsiderable to be of importance in +this inquiry.</p> + +<p>Heat is also carried, and in quantities which exert very considerable +influence upon the weather, from the tropics to the poles by the great +oceanic currents which flow unceasingly from one to the other.</p> + +<p>The most important of these with which we are acquainted is the Gulf +Stream of the Atlantic. Gathering in the South Atlantic, and passing north +through the Caribbean Sea and the Gulf of Mexico, it issues out through +the Bahama Channel, and flows north along the eastern coast of the United +States, but some distance from it, to Newfoundland, and from thence +continuing to the north-east and spreading out over the surface of the +ocean—a portion of it mingling with the waters of the North Atlantic in +passing—it flows up on the western coast of Europe, around the Faroe +Islands, and Spitzbergen, to the polar sea; passing around Greenland, and +perhaps through its Fiords, it descends again through the sounds and +channels of the Arctic regions into Baffin’s Bay, and through Davis’s +Straits, burdened with the icebergs and floes of the polar waters, to +return again<span class="pagenum"><a name="Page_11" id="Page_11">[Pg 11]</a></span> to the South Atlantic. For reasons which will appear in the +sequel, it has comparatively little influence upon the weather of the +United States. Western Europe, however, Greenland, the islands which lie +in its course, and the polar seas, are most materially influenced. +Although not the only cause, it has very much to do with the remarkable +elevation of the isothermal lines over the Northern Atlantic, and upon +Western Europe, as seen upon the map.</p> + +<p>A like oceanic current exists in the Pacific Ocean, the influence of which +may also be traced upon the map by the elevation of the isothermal lines +at the northern extremity of that ocean, and upon the north-west coast of +North America. A vast amount of heat is transported from the tropical to +the temperate and frozen regions of the earth by these great oceanic +currents.</p> + +<p>Another supply is derived from aerial currents which flow from the tropics +toward the poles. These currents exist every where over the entire surface +of the earth, but in more concentrated volumes along the great “lines of +no variation,” and greater magnetic intensity, on the western side of the +great oceans, over the eastern portions of the two continents of North +America and Asia. Not, as meteorological writers suppose, in the upper +portions of the atmosphere, having risen in the trade-wind region and run +off at the top toward the poles by force of gravity, but near, and +sometimes in contact with the earth. The influence of these aerial +currents upon the temperature of the atmosphere, and in producing<span class="pagenum"><a name="Page_12" id="Page_12">[Pg 12]</a></span> the +phenomena we are to consider, is exceedingly important. We shall have +occasion to examine them with great care and minuteness under another +head, for upon them, more than any other portion of the arrangements, +depend not only the diffusion of heat, but also the distribution of +moisture.</p> + +<p>Still another supply of heat, during the sudden changes, at least, is +produced by the action of terrestrial magnetism and electricity. Very +great progress has been made within a short period, in the investigation +of the nature of these agents. The identity, or at least intimate +association or connection of heat, light, electricity, and magnetism, +always suspected, has been in various ways, and by a variety of +experiments demonstrated. The influence of magnetism if distinct from +gravitation, is second only to that; and its agency in producing the +phenomena we are considering is primary and controlling. We will only, in +this connection, ask the reader to note the situation of the north +magnetic poles (for there are two of them); the manner in which the +isothermal lines <i>surround</i> them; the fact that they are <i>poles of cold</i>, +<i>i. e.</i>, that it is colder there than even to the north of them. We shall +recur to this part of the subject again.</p> + +<p>Such, briefly considered, are the principal arrangements by which heat is +diffused over the earth.</p> + +<p>Equally marked by infinite wisdom, and equally interesting and important, +are the arrangements by which moisture is distributed. Doubtless the +general belief is that this is a simple process; that water<span class="pagenum"><a name="Page_13" id="Page_13">[Pg 13]</a></span> evaporates +and rises till it meets a colder stratum of atmosphere, and then condenses +and falls again; or that, according to the Huttonian theory, currents of +air of different temperatures mingle and equalize their heat, and the +aggregate mass when equalized in temperature is cooler, and therefore is +unable to hold as much moisture in solution as the most heated portion +had, and the excess falls in rain. But the process is by no means so +simple, nor is heat the sole or most powerful agent concerned in it. +Currents of air do not mingle, but stratify. Evaporation from the surface +of any given portion of the earth outside of the tropics does not alone +supply that portion with rain. <i>Vast and wonderful, coextensive with the +globe itself, and perfectly connected, is the machinery by which that +supply is furnished even to the most inconsiderable portion of its +surface.</i></p> + +<p>Take your map of North America and note, in this respect, its +peculiarities. It extends from the Isthmus of Darien to the Arctic +regions, and from the 65th to the 160th meridian of west longitude from +Greenwich, and has upon its surface a type of every climate in the world. +For the purpose of simplifying and illustrating the matter in hand, let us +divide it into five sections. Let the first section embrace Central +America and Southern Mexico, south of 28°; the second, Northern Mexico and +Southern New Mexico, California, etc., between the parallels of 28° and +32°; the third, Northern California, Utah, Southern Oregon, and Western +New Mexico, north of the parallel of 32°; the fourth, the entire +continent north of 42°; and the fifth, the eastern United States, east of +the meridian of 100°. These divisions are not intended to be entirely +accurate in their separation, but substantially so for the purpose of +illustrating the differences which exist in each.</p> + +<p>The accompanying diagram shows approximately, by dotted lines, the +divisions.</p> + +<p> </p> +<p><span class="pagenum"><a name="Page_14" id="Page_14">[Pg 14]</a></span></p> +<p class="center"><strong>Fig. 2.</strong></p> +<div class="figcenter"><img src="images/i0035.jpg" alt="" /></div> +<p> </p> + +<p><span class="pagenum"><a name="Page_15" id="Page_15">[Pg 15]</a></span>Now let us see in what a diverse manner, and to what a different extent, +they are severally supplied with moisture.</p> + +<p>Central America and Southern Mexico lie within the tropics—their rains +are tropical rains. The season is divided into wet and dry, as are the +seasons of all tropical countries which are not rainless. During the rainy +season it rains a portion of nearly every day, and during the dry season +the sky is clear, the air is pure, and rain seldom falls.</p> + +<p>All around the earth within the tropics, over the land and over the sea, +there is a belt of almost daily rains, varying in width, north and south, +in different sections, but averaging about five hundred miles. This belt +of daily rains is formed at and by the meeting of N. E. and S. E. trades, +and travels north and south with them, as they do with the sun, +<i>encircling the globe</i>. By this narrow belt a portion of the earth’s +surface, an average of some 35° of latitude, is supplied with moisture. +Wherever it is situated at any given period, the tropical rainy season +exists; and when it is absent in its northern or southern transit, the dry +season prevails. Southern Mexico is within the range of this moving belt, +and in its course to the northward with the sun, in our summer from May to +October, it arrives over, and covers that country with a rainy season. +When the sun returns to the south, taking with it the trades and this belt +of tropical rains, that portion of Mexico is without rain, and dry, and so +continues until the rainy belt returns in the following year. While the<span class="pagenum"><a name="Page_16" id="Page_16">[Pg 16]</a></span> +belt is over Southern Mexico it is nearly all <i>precipitation</i>, and there +is little <i>evaporation</i>; while that belt is <i>absent</i> it is all +<i>evaporation</i>, with little or no <i>rain</i>. Surely this is not consistent +with the prevailing belief of simple evaporation, ascent to a colder +stratum, commingling, and condensation, and rain. Southern Mexico at least +is not supplied by mere evaporation from its surface, and must therefore +form an exception to that belief, and to the Huttonian theory.</p> + +<p>But we shall recur again to the peculiarity of distribution within the +tropics.</p> + +<p>Turn now for a brief space to Northern Mexico, Southern New Mexico, and +Southern California. In Northern Mexico, Southern New Mexico, Utah, and +California, between the parallels of 28° and 32°, and particularly west of +the mountain ranges, we find an almost rainless region, sterile and +worthless, resembling that which is found upon nearly the same parallels +of north latitude in Northern Africa, Egypt, Arabia, Beloochistan, +Afghanistan, and North-western India; and in corresponding latitudes south +of the Equator, in Peru, a portion of Southern Africa, and the northern +and middle portions of New Holland. Why Northern Mexico and the other +countries named are thus sterile and comparatively rainless, we shall see +hereafter, when we examine critically the machinery of distribution as it +operates within the tropics. It is the fact that it is thus sterile and +rainless to which we desire to call attention in this place.</p> + +<p><span class="pagenum"><a name="Page_17" id="Page_17">[Pg 17]</a></span>Mr. Bartlett thus describes it:</p> + +<div class="blockquot"><p>“On leaving the head waters of the Concho, nature assumes a new +aspect. Here shrubs and trees disappear, except the thorny chaparral +of the deserts; the water-courses all cease, nor does any stream +intervene until the Rio Grande is reached, three hundred and fifty +miles distant, except the muddy Pecos, which, rising in the Rocky +Mountains, near Santa Fé, crosses the great desert plain west of the +Llano Estacado, or Staked Plain.</p> + +<p>“From the Rio Grande to the waters of the Pacific, pursuing a +westerly course along the 32d parallel, near El Paso Del Norte, there +is no stream of a higher grade than a small creek. I know of none but +the San Pedro and the Santa Cruz—the latter but a rivulet, losing +itself in the sands near the Gila—the other but a diminutive stream, +scarcely reaching that river. At the head-waters of the Concho, +therefore, begins that great desert region, which, with no +interruption save a limited valley or bottom-land along the Rio +Grande, and lesser ones near the small courses mentioned, extends +over a district embracing sixteen degrees of longitude, or about a +thousand miles, and is wholly unfit for agriculture. It is a +desolate, barren waste, which can never be rendered useful for man or +beast, save for a public highway.”—<i>Bartlett’s Personal Narrative</i>, +vol. i. p. 138.</p></div> + +<p>Turning now to Central and Upper California, and Utah, and Southern +Oregon, we find still another peculiarity. Like Southern Mexico, they have +a rainy and dry season, but at a different period, and for a different +reason. The dry season of California, etc., is the summer of the northern +hemisphere, and her rainy season the winter. <i>California</i> is, therefore, +<i>dry</i> when Southern <i>Mexico</i> is <i>wet</i>, and <i>vice versâ</i>. The belt of rains +which supplies California with moisture during her rainy seasons is the +belt of <i>extra-tropical</i> rains, which extends from the northern limit of +the north-east trades to the poles, encircling the earth. The southern +edge of this extra-tropical belt is <i>carried up</i> on the western coast of +America, and in<span class="pagenum"><a name="Page_18" id="Page_18">[Pg 18]</a></span> that portion of the continent in <i>summer</i>, when the sun +and trades, and the inter-tropical rainy belt travel to the north, and +uncover California, etc., leaving them without rain for a period of about +six months.</p> + +<p> </p> +<p class="center"><strong>Fig. 3.</strong></p> +<div class="figcenter"><img src="images/i0039.jpg" alt="" /></div> +<p class="center"><strong>IN SUMMER.</strong></p> +<p> </p> + +<p>As the sun, with the trades, travels south, the southern edge of the belt +of extra-tropical rain follows, and covers California, etc., again +extending<span class="pagenum"><a name="Page_19" id="Page_19">[Pg 19]</a></span> gradually from the north to the south, and thus their wet +season returns. The annexed diagrams by the shading will show the +situation of the rainy belts which cover Mexico, Utah, New Mexico, and +California in summer and winter, and that the belts of rains are entirely +distinct and different in character.</p> + +<p> </p> +<p class="center"><strong>Fig. 4.</strong></p> +<div class="figcenter"><img src="images/i0040.jpg" alt="" /></div> +<p class="center"><strong>IN WINTER.</strong></p> +<p> </p> + +<p>Here again in this section of the continent, as in<span class="pagenum"><a name="Page_20" id="Page_20">[Pg 20]</a></span> Mexico, evaporation is +going on for six months of the year, and were it not for the return of the +belt of rains from the north, in the fall, would go on for the entire year +without precipitation; and for the other six months precipitation is +vastly in excess. Nor can this be reconciled with, or explained by, the +Huttonian or any other received theory of rain. Here again it is obvious +that evaporation alone, however great or long continued, will not furnish +the evaporating section with rain.</p> + +<p>The northern portion of the continent lies beneath the zone of +extra-tropical rains, and north of the northern limit of the N. E. +trades—is never uncovered from it, and has no distinct rainy or dry +season, although more rain falls at certain periods, and in certain +localities, than at others. The climate of that part of Oregon which lies +upon the Pacific, and the character of its rains, resemble those of +North-western Europe, and will be further explained hereafter.</p> + +<p>Coming to the portion of the continent which we occupy, the 5th section, +we find it different still—a most favored region. Portions of it—Eastern +Texas, for instance—are upon the same parallels of latitude as the +rainless regions of Northern Mexico, etc. Eastern Texas, however, is not +rainless. Other portions are upon the same parallels as California, etc., +yet have no distinct rainy and dry season. We repeat, this section is a +most favored region—without a parallel upon any portion of the earth’s +surface,<span class="pagenum"><a name="Page_21" id="Page_21">[Pg 21]</a></span> except, in degree, in China and some other portions of Eastern +Asia.</p> + +<p>It is not only without a distinct rainy and dry season, but it is watered +by an average, annually, of more than forty inches of rain, while Europe, +although bounded on three sides by seas and oceans, and apparently much +more favorably situated, receives annually an average of only about +twenty-five—if we except Norway, and one or two other places, where the +fall is excessive. The distribution of this supply of moisture over the +United States is, in other respects, wonderful. Iowa, in the interior of +the continent, far away from the great oceans, on the east or west, or the +Gulf of Mexico on the south, receives fifty inches; some ten or fifteen +inches more than fall upon the slope east of the Alleghanies, and +contiguous to the great Atlantic (from which all our storms are, +erroneously, supposed to be derived), and the average over the entire +great interior valley is about forty-five inches, falling at all seasons +of the year.</p> + +<p>Observe, then, by way of recapitulation: Southern Mexico has a rainy +season furnished by the belt of <i>inter</i>-tropical rains, which <i>travels up +over it from the south</i> in summer. California has a rainy season, which is +furnished by the <i>extra</i>-tropical belt of rains, which travels <i>down from +the north</i>, and covers it in winter. Northern Mexico and the adjoining +regions west of the 100th meridian are between the limits of the two, and +neither travels far enough to reach them, except for brief and uncertain +periods; they are<span class="pagenum"><a name="Page_22" id="Page_22">[Pg 22]</a></span> comparatively rainless; while the eastern portion of +the continent, <i>in all latitudes</i>, unlike the others, is without a +distinctly marked dry season, or a rainless region, and with the exception +of occasional droughts, is abundantly supplied with rain at all seasons of +the year.</p> + +<p>And now, what is the explanation of all this? What produces the +extra-tropical belt of regular rains surrounding the earth, north of the +parallel of 30° north, in some places, and 35° in others, extending to the +pole, with its southern edge traveling up ten or more degrees in summer, +leaving large portions of the earth subject to a dry season; and back +again in the winter to give them a rainy one? What produces the narrow +belt of inter-tropical rains, encircling the earth; traveling up and down +every year over an average of 35° of latitude, supplying every portion of +it alternately with rain? And what connects the two together over the +eastern portion of North America, so as to leave no distinctly marked wet +and dry season, and no rainless and sterile portion there? Are all these +the result of simple evaporation, ascent to a colder region, condensation, +and descent again? Demonstrably not. Of the forty inches which fall +annually upon the middle and eastern portions of the United States, an +average probably of one-half or twenty inches, runs off by the rivers to +the ocean, or is carried away eastward by the westerly and north-westerly +evaporating winds. The same is true, in degree, of the rain which falls +upon the other portions. Evaporation,<span class="pagenum"><a name="Page_23" id="Page_23">[Pg 23]</a></span> therefore, could not keep up the +supply. From whence, then, does it come? this twenty inches, thus lost by +the rivers and winds, and with such wonderful regularity every year.</p> + +<p>“All the rivers run into the sea, yet the sea is not full. <i>Note the place +whence the rivers come, hither they return again.</i>”</p> + +<p>But how is it that they thus return with such wonderful regularity, in a +narrow traveling belt of daily rains within the tropics, and a movable +belt of irregular rains without the tropics, extending to the poles, +leaving a space on each side of the equator encircling the earth in like +manner (except at two points, <i>viz.</i>, Eastern Asia and Eastern North +America), from which they do not go, and to which they do not return, and +which is almost entirely unfurnished with rain? And all this without any +relation, whatever, to the contiguity of the oceans? Obviously this is not +the work of mere evaporation, or of the accidental or irregular +commingling of winds with different dew points, or quantities of moisture +in solution, or accidental, irregular changes of barometric pressure. <i>It +is one vast, wonderful, connected, and regular system—co-extensive with +the globe—necessary to the return of moisture from the oceans upon the +most inconsiderable portion of it, and to the condensation of the local +moisture of evaporation; and by it the waters are returned from the oceans +as regularly and bountifully upon the far interior of the great continents +in the same latitudes, as upon the “isles which rest in their bosoms.”</i></p> + + +<p> </p><p> </p> +<hr style="width: 50%;" /> +<p><span class="pagenum"><a name="Page_24" id="Page_24">[Pg 24]</a></span></p> +<h2><a name="CHAPTER_II" id="CHAPTER_II"></a>CHAPTER II.</h2> + +<p>Before proceeding to an examination of this connected atmospheric +machinery, and an investigation of the particular ocean from which our +rivers return, it may be well to look at the form in which they appear to +return, that we may have a clear understanding of terms.</p> + +<p>They seem to return in the form of clouds, and in storms and showers, +although, in truth, they return in regular, uniform, ordinarily invisible +currents, and the storms and showers are but condensations in, and +discharges from portions of those currents, aided by the local moisture of +evaporation.</p> + +<p>The term <i>storms</i>, seems to be used by European meteorologists to denote +what we term thunder showers or gusts, and tornados; while what we call +storms are denominated by them regular rains. As the terms are extensively +in use in this country, we must adhere to the meaning attached to them +<i>here</i> rather than <i>there</i>.</p> + +<p>Storms with us, then, are regular rains of from six to forty-eight or more +hours’ continuance: generally without lightning, or thunder, or gusts, and +usually with wind of more or less force, from some easterly point. They +are called north-east storms,<span class="pagenum"><a name="Page_25" id="Page_25">[Pg 25]</a></span> or south-east storms, according to the +point from which the surface winds blow. Practically we shall find that +this distinction is of some importance, for the north-east storms are the +longest, lasting generally twenty-four hours, or more, while the +south-east ones seldom, if ever, continue as long.</p> + +<p>These storms extend over a considerable surface, rarely less than one +hundred miles in one direction or another, and sometimes fifteen hundred, +or more. Distinct showers cover but a small surface, sometimes not more +than forty to one hundred rods, as in the tornado, and rarely more than +ten miles. Belts of showers, each new one forming a little more to the +south, often, in summer, pass across the country, following each other in +succession; and these belts may be of considerable width, say thirty to +one hundred and fifty miles.</p> + +<p>The clouds which constitute the storms and showers differ in appearance +and character, as well in the active as in the forming state. Clouds are +of distinct characters, alike, substantially, every where under like +circumstances; and a distinct nomenclature has been applied to them by Dr. +Howard, of London. He notes three kinds of primary clouds: <i>viz.</i>, cirrus, +stratus, and cumulus; and inasmuch as the boundary line between them is +not very distinct, certain compounds of the three, <i>viz.</i>: cirro-stratus, +cirro-cumulus, and cumulo-stratus. This nomenclature is every where +received, and portions of it are of great practical importance.</p> + +<p>The three principal descriptions of cloud, <i>viz.</i>: the<span class="pagenum"><a name="Page_26" id="Page_26">[Pg 26]</a></span> cirrus, the +stratus, and the cumulus, we have very much as they have in Europe, and +doubtless as they exist every where outside of the tropics. The nimbus, +another cloud described by him, is not distinct from the cumulus or +stratus. An isolated, limited thunder-shower in a clear sky, presents the +appearance of a nimbus, as shown in the cuts, but the basis of it is a +cumulus, and it differs from an ordinary fair-weather cumulus merely in +the dark and fringe-like appearance of the rain as it is falling from its +lower surface, and sometimes in the existence of a stratus above and in +connection with it. A similar form is often assumed by the peculiar clouds +of the N. W. winds in March or November, when they assume the form of +<i>squalls</i>, and drop flurries of snow. The nimbus, therefore, is not a +distinct cloud, but an appearance which the cumulus, stratus, or +cirro-stratus has in a stormy or showery state, and does not deserve a +distinct name. It is but a cumulus, or a stratus, or cirro-stratus +dissolving in snow or rain. It is important that this term should be +abandoned. It tends to confuse and prevent a clear understanding of the +difference in the character of the clouds, and in relation to which +precision is both difficult and desirable.</p> + +<p>The figures on pages 27 and 29, show the different kinds of clouds as +designated by Howard. They are copied from the engravings in the sixth +edition of Maury’s “Sailing Directions.”</p> + +<p><span class="pagenum"><a name="Page_27" id="Page_27">[Pg 27]</a></span></p> +<p class="center"><strong>Fig. 5.</strong></p> +<div class="figcenter"><img src="images/i0048tmb.jpg" alt="" /><br /> +<a href="images/i0048.jpg"><small>Larger Image</small></a></div> +<p><span class="pagenum"><a name="Page_28" id="Page_28">[Pg 28]</a></span></p> +<p> </p> +<p><span class="pagenum"><a name="Page_29" id="Page_29">[Pg 29]</a></span></p> +<p class="center"><strong>Fig. 6.</strong></p> +<div class="figcenter"><img src="images/i0050tmb.jpg" alt="" /><br /> +<a href="images/i0050.jpg"><small>Larger Image</small></a></div> +<p><span class="pagenum"><a name="Page_30" id="Page_30">[Pg 30]</a></span></p> +<p> </p> +<p> <span class="pagenum"><a name="Page_31" id="Page_31">[Pg 31]</a></span></p> + +<table border="0" cellpadding="0" cellspacing="5" summary="figures"> +<tr><td>Figure 5.</td></tr> +<tr><td><span style="margin-left: 1em;">The cirrus is indicated by</span></td><td><span class="spacer"> </span></td><td>1 bird.</td></tr> +<tr><td><span style="margin-left: 1em;">The cirro-cumulus by</span></td><td> </td><td>2 <span style="margin-left: .75em;">"</span></td></tr> +<tr><td><span style="margin-left: 1em;">The cirro-stratus by</span></td><td> </td><td>3 <span style="margin-left: .75em;">"</span></td></tr> +<tr><td><span style="margin-left: 1em;">The cumulo-stratus by</span></td><td> </td><td>4 <span style="margin-left: .75em;">"</span></td></tr> +<tr><td> </td></tr> +<tr><td>Figure 6.</td></tr> +<tr><td><span style="margin-left: 1em;">The cirrus by</span></td><td> </td><td>1 <span style="margin-left: .75em;">"</span></td></tr> +<tr><td><span style="margin-left: 1em;">The cumulus by</span></td><td> </td><td>2 <span style="margin-left: .75em;">"</span></td></tr> +<tr><td><span style="margin-left: 1em;">The stratus by</span></td><td> </td><td>3 <span style="margin-left: .75em;">"</span></td></tr> +<tr><td><span style="margin-left: 1em;">The nimbus by</span></td><td> </td><td>4 <span style="margin-left: .75em;">"</span></td></tr></table> + + +<p>How far these representations correspond with the actual appearance of the +different compound forms in England, I can not say. But although they +convey a <i>general</i> idea, <i>they are not sufficiently accurate for practical +illustration or observation here</i>. Indeed Howard himself has omitted from +his last edition his plate of the clouds, assigning as a reason, “that the +real student will acquire his knowledge in a more solid manner by the +observation of nature, without the aid of drawings, and that the <i>more +superficial are liable to be led into error by them</i>.” The collection of +forms in the cuts <i>does not contain some very important ones</i>, and +contains some which are not distinct forms; but they may aid us somewhat +in this inquiry, and, therefore, I have copied them. It is well, also, for +the reader to have the generally received description before him.</p> + +<p>But for the purpose of <i>practical</i> illustration hereafter, and greater +precision, I shall follow a somewhat different<span class="pagenum"><a name="Page_32" id="Page_32">[Pg 32]</a></span> order in describing them, +and introduce two forms of <i>scud</i> quite as important, practically, as any +other.</p> + +<p>First, then, commencing at the earth, we have what may be properly termed +<i>fog</i>, or low fog. This forms, in still clear weather, in the valleys, and +over the surface of the rivers and other bodies of water, during the +night, and most frequently the latter part of it, and is at its acmé at +sunrise, or soon after, limiting vision horizontally and perpendicularly, +and dissolving away during the forenoon. It is rarely more than from two +to four hundred feet in height at its upper surface, and often much less, +and is composed of vesicular condensed vapor, sometimes sufficiently dense +to fall in mist, and is doubtless in composition substantially what the +clouds are in the other strata of the atmosphere, as observed by us, or +passed through by aeronauts. I have never seen it carried up to any +considerable height into the other strata by any of the supposed ascending +currents, to form permanent clouds, and shall have occasion to allude to +the fact in another connection. It disappears usually before mid-day, and +has, when thus formed, no connection with any clouds which furnish rain.</p> + +<p>To this Dr. Howard originally gave the name of stratus, and so it is +represented upon the cut; but the latter term may be with greater +propriety applied to the smooth uniform cloud in the superior strata from +which the rain or snow is known to fall, and I shall retain and so apply +it.</p> + +<p>The next in order, ascending, is high fog. This<span class="pagenum"><a name="Page_33" id="Page_33">[Pg 33]</a></span> is usually from one to +two thousand feet in height at its lower surface. It forms, like low fog, +during the night and in still weather; and is rarely, if ever, connected +with clouds which furnish rain. It breaks away and disappears between ten +and twelve in the forenoon, usually passing off to the eastward. This fog +is most commonly seen in summer and autumn, particularly the latter, and +unless distinguished from cloud will deceive the weather-watcher. It is +readily distinguishable. Although often very dense, obscuring the light of +the sun as perfectly as the clouds of a north-east storm, it differs from +them. It forms in still clear weather, is present only in the morning, is +perfectly uniform, and, before its dissolution commences, without breaks, +or light and shade, or apparent motion, and unaccompanied by scud or +surface wind. The storm clouds are never entirely uniform, or without +spots of light and shade, by which their nature can be discerned, and +rarely, when as dense as high fog, without scud running under them and +surface winds.</p> + +<p>There is another fog still, connected with rain storms, but it does not +often precede them; occurring at all seasons, but most commonly in +connection with the warm S. E. thaws and rains of winter and spring; and +which usually comes on <i>after</i> the rain has commenced and continued for +awhile, and the easterly wind has abated; occupying probably the entire +space from the earth to the inferior surface of the rain clouds or +stratus. Practically this does not require any further notice. It is an +<i>incident</i> of<span class="pagenum"><a name="Page_34" id="Page_34">[Pg 34]</a></span> the storm. When formed it remains while the storm clouds +remain, and passes off with them. It is sometimes exceedingly dense in +February and March, when it accompanies a thaw, and if there is a +considerable depth of snow, it has the credit of aiding essentially in its +dissolution.</p> + +<p>Mingled with the smoke of London, it produced there the memorable <i>dark +day</i> of the 24th of February, 1832, and at various other times has +produced others of like character. (See Howard’s Climate of London, vol. +iii. pp. 36, 207, 303.) These fogs have been so dense there that every +kind of locomotion was dangerous, even <i>with lanterns, at mid-day</i>.</p> + +<p>The next in order, ascending, are the storm scud, which float in the +north-east or easterly, south-east or southerly wind, before and during +storms.</p> + +<p>These, as the reader will hereafter see, are, <i>practically</i>, very +important forms of cloud condensation—although they have found no place +in any practical or scientific description given of the clouds, and are +not upon the cuts. They are patches of foggy seeming clouds of all sizes, +more or less connected together by thin portions of similar condensation, +often passing to the westward, south-westward, north-westward, or +northward with great rapidity. Their average height is about half a mile, +but they often run much lower. They are usually of an “ashy gray” color. +The annexed cut shows one phase of them, from among many taken by +daguerreotype. The arrows pointing to the west show the scud distinguished +from the smooth partially formed<span class="pagenum"><a name="Page_35" id="Page_35">[Pg 35]</a></span> stratus above. This view was taken a few +hours prior to the setting in of a heavy S. E. rain storm. It is a +northerly view.</p> + +<p> </p> +<p class="center"><strong>Fig. 7.</strong></p> +<div class="figcenter"><img src="images/i0056.jpg" alt="" /></div> +<p> </p> + +<p>At about the same height, but in a <i>different state of the atmosphere</i>, +float the peculiar fair-weather clouds of the N. W. wind. They usually +form in a clear sky, and pass with considerable rapidity to the S. E. +Sometimes they are quite large, approaching the cumulus in form, and +white, with dark under surfaces, and at others, in the month of November +particularly, are entirely dark, and assume the character of squalls and +drop flurries of snow; and then resemble the nimbus of Howard. They assume +at<span class="pagenum"><a name="Page_36" id="Page_36">[Pg 36]</a></span> different times and in different seasons, different shapes like those +of the scud, the cumulus, or the stratus.</p> + +<p> </p> +<p class="center"><strong>Fig. 8.</strong></p> +<div class="figcenter"><img src="images/i0057.jpg" alt="" /></div> +<p> </p> + +<p>They form and float in the peculiar N. W. current which is usually a +fair-weather wind, and are never connected with storms. In mild weather +they are usually white, and in cold weather sometimes very black, and at +all times differ <i>in color</i> from the ashy gray scud of the storm. This +variety is not represented upon the general cuts. The annexed diagram +shows one phase of them, but they are readily observable at all seasons of +the year, when the N. W. wind is prevailing; differing in appearance +according to the season. Let these, as well as the storm scud, be +carefully observed and studied by the reader, and let no opportunity to +familiarize himself with their appearance be lost. A brief glance at +each recurrence of easterly or north-westerly wind will suffice.</p> + +<p> </p> +<div class="figcenter"><img src="images/i0059.jpg" alt="" /></div> +<p class="center"><strong>SUMMER CUMULI.</strong></p> +<p> </p> + +<p><span class="pagenum"><a name="Page_37" id="Page_37">[Pg 37]</a></span>The <i>cumuli</i> appear in isolated clouds of every size, or in vast clouds +composed of aggregated masses, as the peculiar cloud of the thunder +shower. They form as low down as the scud or fair-weather cloud of the N. +W. wind, which, for convenience, I will call N. W. <i>scud</i>; and often in +violent showers, and particularly in hail storms, extend up as far as the +density of the atmosphere will permit them to form. Professor Espy thinks +he has measured their tops at an altitude of ten miles. Others have +estimated their height, when most largely developed, at twelve miles; but +it is very doubtful whether the atmosphere can contain the moisture +necessary to form so dense a cloud at that elevation. It is their immense +height, however, whether it be six, or eight, or ten miles, together with +the sudden and violent electric action, condensing suddenly all the +moisture contained in the atmosphere within the space occupied by the +cloud, which produces such sudden and heavy falls of rain or hail. As the +rain drops or hail, when formed at such an elevation, in falling through +the partially condensed vapor of the cloud must necessarily enlarge by +accretion from the particles with which they come in contact, and probably +also by attraction, their size when they reach the earth, though +frequently very considerable, is not a matter of astonishment. The cumulus +is represented in the general plate with sufficient accuracy to show its +peculiar character.</p> + +<p><span class="pagenum"><a name="Page_38" id="Page_38">[Pg 38]</a></span>In summer, when the air is calm, the weather warm, and no storm is +approaching, there is always, in the day time, a tendency to the formation +of cumuli. This tendency exhibits itself about ten o’clock in the +forenoon, and they gradually form and enlarge until about two in the +afternoon; and after that, if they do not continue to enlarge and form +showers, they melt away and disappear before nightfall. Sometimes in July +and August the atmosphere will be studded with them at mid-day, floating +about three-quarters of a mile from the earth (in a level country), gently +and slowly away to the eastward. At times it may seem as if they must +coalesce and form showers, yet they frequently do not, but gradually melt +away, as before stated.</p> + +<p>The cumulus is the principal cloud of the tropics, and is not often seen +with us except in summer, or when our weather is tropical in character.</p> + +<p>The engraving on the preceding page, shows a phase of these fair-weather +summer cumuli.</p> + +<p>The last in order occupying (with their compounds) the higher portions of +the atmosphere, are the cirrus and stratus. The cirrus is often the +skeleton of the other, and precedes it in formation.</p> + +<p>These are the proper clouds of the storm, in our sense of the term. While, +however, the cirrus remains a cirrus, it furnishes no rain. When it +extends and expands, and its threads widen and coalesce into cirro-stratus +and stratus, or it induces a layer of stratus below it, the rain forms.</p> + +<p>The following is Dr. Howard’s description of cirrus:<span class="pagenum"><a name="Page_39" id="Page_39">[Pg 39]</a></span> “Parallel, flexuous +or diverging fibers, extensible by increase in any or in all directions. +Clouds in this modification appear to have the least density, the greatest +elevation, and the greatest variety of extent and direction. They are the +earliest appearance after serene weather. They are first indicated by a +few threads penciled, as it were, on the sky. These increase in length, +and new ones are in the mean time added to them. Often the first-formed +threads serve as stems to support numerous branches, which in their turn, +give rise to others.”</p> + +<p>The illustrations in the general cut are imperfect, and do not represent +the delicate fibers of the cloud, for it is a difficult cloud to +daguerreotype or engrave, but the representation is sufficiently accurate +to give the reader a general idea of the different varieties, and enable +him to discover them readily by observation. They are the most elevated +forms, always of a light color, and often illuminated about sunset by the +rays of the sun shining upon their inferior surface; the sun, however, +often illuminates, in like manner, the dense forms of cirro-stratus, and +the latter, from their greater density, are susceptible of a brighter and +more vivid illumination.</p> + +<p>The stratus is a smooth, uniform cloud—the true rain cloud of the storm; +often forming without much cirrus above, or connected with it. It may be +seen in its partially formed state in the bank in the west, at nightfall, +or in the circle around the moon in the night. When it becomes +sufficiently condensed, rain always falls from it, but in moderation. If +there be<span class="pagenum"><a name="Page_40" id="Page_40">[Pg 40]</a></span> large masses of scud running beneath it for its drops to fall +through (especially as is sometimes the case, in two or more currents), +the rain may be very heavy. But more of this hereafter.</p> + +<p> </p> +<p class="center"><strong>Fig. 10.</strong></p> +<div class="figcenter"><img src="images/i0063.jpg" alt="" /></div> +<p> </p> + +<p>The annexed cut shows the forming stratus, light and thin, passing to the +east, as indicated by the short arrows just before a storm, while the scud +beneath is running to the west.</p> + +<p>It was copied from a daguerreotype view, facing northwardly.</p> + +<p>Intermediate between the fibrous, tufted, cirrus, and the smooth uniform +stratus, there is a variety of forms partaking more or less of the +character of one or the other, and termed <i>cirro-stratus</i>. No single +correct representation of cirro-stratus as a distinct<span class="pagenum"><a name="Page_41" id="Page_41">[Pg 41]</a></span> cloud, can be +given—but several varieties will be hereafter alluded to, under the head +of prognostics. Several modifications are represented with tolerable +accuracy upon the cuts.</p> + +<p>The cirro-cumulus is a collection in patches of very small distinct heaps +of white clouds; they are called fleecy clouds, from their resemblance to +a collection of fleeces of wool, and are imperfectly represented on the +general cut. They do not appear often, and are usually <i>fair-weather +clouds</i>.</p> + +<p>This form has none of the characteristics of the cumulus, and does not +appear in the same stratum. It was probably called cumulus because its +small masses are distinct, as are those of the ordinary cumulus. It occurs +in the same stratum as cirro-stratus, and properly belongs to that +modification. I retain the name inasmuch as the cloud is of some practical +importance.</p> + +<p>The cumulo-stratus is seldom seen in our climate, as it is represented in +the cut. Stratus condensation <i>above</i>, and in connection with cumulus +condensation, is not uncommon, but that precise form is rare.</p> + +<p>This, too, is practically of no consequence, and I shall take no further +notice of it.</p> + +<p>Recapitulating, I give (in a tabular form) the three principal strata and +their modifications, located with sufficient accuracy for illustration. +The clouds which are found in an upper or lower portion of a stratum are +so represented by the location of their names; those which appear at all +heights in the stratum, with the names across. The elevation is the +average <span class="pagenum"><a name="Page_42" id="Page_42">[Pg 42]</a></span>one—although there is no limit to the cirrus above, except the +absence of sufficient moisture. It was seen by Guy Lussac, and has been by +other aeronauts, at an elevation of five miles, or more, when too delicate +to be visible below.</p> + +<p> </p> +<div class="figcenter"><img src="images/chart42.png" alt="" /></div> +<p> </p> + + +<p>With the assistance of this table of elevations, and a careful +observation, the reader can soon become familiar with the forms of clouds +and their relative situations.</p> + + +<p> </p><p> </p> +<hr style="width: 50%;" /> +<p><span class="pagenum"><a name="Page_43" id="Page_43">[Pg 43]</a></span></p> +<h2><a name="CHAPTER_III" id="CHAPTER_III"></a>CHAPTER III.</h2> + +<p>Having thus taken a brief view of the different clouds, let us return to +the inquiry, from what ocean, and by what machinery, <i>our</i> “rivers +return.”</p> + +<p>Not wholly or mainly from the North Atlantic, although it lies adjacent to +us, and they often <i>seem</i> to do so; for, first, all storms, showers, and +clouds, which furnish, <i>independently</i>, any appreciable quantity of rain +to the United States, and even adjacent to the Atlantic, or indeed to the +Atlantic itself, come from a westerly point, and pass to the eastward. +<i>This is a general, uniform, and invariable law, although there is in +different places, and in the same place at different times, some variation +in their direction; ranging in storms from W. by S. to S. S. W., and in +showers between S. W. and N. W., to the opposite easterly points of the +compass; the most general direction, east of the Alleghanies, being from +W. S. W. to E. N. E.</i></p> + +<p>But do we not see, you inquire—at least those of us who live east of the +Alleghanies—that when it rains, the wind is from the eastward; and that +the <i>clouds</i> follow the wind from the east to the west? You do indeed, +generally, in all considerable storms, observe that the wind blows from +some easterly point, and that <i>seeming</i> clouds are blown by it to the +<span class="pagenum"><a name="Page_44" id="Page_44">[Pg 44]</a></span>westward; but what you see, and call clouds, are not the clouds which +furnish the rain. Far above the seeming clouds you notice, directly over +your head when it rains or snows, are the rain or snow clouds, dense and +dark, passing to the eastward, how strong soever the wind may blow from +the quarter to which they tend, or any other quarter, between you and +them. What you see below them are <i>scud</i>. So the sailors call them, and so +I have termed them. It is a “dictionary name,” and a good one, expressive +of a distinction between them and <i>clouds</i>. They are thin, and the sun +shines through them, although with some difficulty, when the rain clouds +above are absent or broken. <i>This east wind and the scud are not the +storm, or essential parts of it.</i> Storms occasionally exist, particularly +in April, without either. They are but <i>incidents</i>, <i>useful</i>, but not +<i>necessary incidents</i>, as all surface winds are.</p> + +<p>If you could see a section of the storm, you would see the rain cloud +above, moving to the east, and the scud beneath running to the west, as +indicated by the arrows in the cut on page <a href="#Page_40">40</a>. Opportunities frequently +occur when these <ins class="correction" title="original: appearnces">appearances</ins> may be seen. Storms are sometimes very long, +a thousand miles, perhaps, from W. S. W. to E. N. E., and not more than +one to three hundred miles wide from S. E. to N. W., and their sides, +particularly the northern ones, regular, and without extensive partial +condensation. Then the storm cloud above, moving to the eastward, and the +scud running under to the westward, may be seen as in the cut.</p> + +<p><span class="pagenum"><a name="Page_45" id="Page_45">[Pg 45]</a></span>So they may be seen before, at the commencement, and at the conclusion of +easterly storms, in a majority of cases, and the reader is desired to +notice them particularly as opportunities occur.</p> + +<p>The term <i>running</i>, too, is a very expressive one, used by sailors as +applicable to <i>scud</i>. For while the forming or formed storm clouds may be +moving moderately along, at the rate of twelve to fifteen or twenty miles +an hour, from about W. S. W. to E. N. E., the scud may be running under them +in a different direction—opposite, or diagonal, or both—at the rate of +twenty, fifty, sixty, and, in hurricanes, even ninety miles an hour. You +have doubtless seen these scud running from N. E. to S. W., and without +dropping any moisture, a day or sometimes two days, before the storm +coming from the S. W. reached the place where you were; and then, sometimes +the storm cloud slipped by to the southward, and the expected storm at +that point proved “a dry northeaster.” Sometimes the condensation, +although sufficiently dense to influence and attract the surface +atmosphere, and create an easterly wind and scud, does not become +sufficiently dense to drop rain, and then, too, we have a dry northeaster, +which may melt away or increase to a storm after it has passed over us. <i>I +have never seen, except, perhaps, in a single instance, one of these +masses of scud, however dense, which had not a rain (stratus) cloud above +it, drop moisture enough to make the eaves run.</i> So you see it may be +true, and if you will examine carefully, you may satisfy yourself that it +is true, that the storms all move from a<span class="pagenum"><a name="Page_46" id="Page_46">[Pg 46]</a></span> westerly point to the eastward, +notwithstanding the wind under them is blowing, and the scud under them +are running to the westward.</p> + +<p>There are many other methods by which the reader may determine this matter +himself. He may catch an opportunity for a view, when there is a break in +the stratus cloud above, and the sun or moon, no longer obscured by the +<i>storm cloud</i>, shines through the scud beneath. Then he may see they are +moving in different directions. <i>The upper cloud, if there be any of it +left, always to the eastward.</i></p> + +<p>Again, we may see the storm approach from the westward, as it often does, +before the wind commences to blow, and the scud to run from the eastward; +particularly snow storms in winter, and the gentle showers and storms of +spring.</p> + +<p>Again, thunder storms, we know, come from the westward, and apparently +against an east wind. It is sometimes said they approach from the east, +but it is a mistake. During thirty years attentive observation in +different localities, I have never seen an instance. They sometimes <i>form</i> +over us, or just east of us, or one may form at the east and another at +the west, and as they <i>spread out in forming</i>, one may seem to be coming +from the east, or there may be an easterly current, with dense flocculent +scud at the under surface of the shower cloud running westward, but they +finally pass off to the eastward, and never to the westward. It is +possible that a <i>patch of scud</i> may become sufficiently <i>dense</i> and +<i>electrified</i> to make a <i>shower</i>, but I have never observed one. Such an<span class="pagenum"><a name="Page_47" id="Page_47">[Pg 47]</a></span> +<i>apparent</i> instance may be found recorded in “Sillman’s Journal,” vol. +xxxix. page 57. I have seen the scud assume a distinct cumulus form, but +never to become sufficiently dense to make a thunder shower.</p> + +<p>Thunder and lightning sometimes attend portions of regular storms in +spring and autumn, but the thunder is always heard first in the west, and +last in the east.</p> + +<p>Again, there are admitted facts with which you are conversant, which prove +this proposition. When it has been raining all day, and just at night the +storm has nearly all passed over to the eastward, and the sun shines under +the western edge of it, and “<i>sets clear</i>,” as it is termed—you say that +“<i>it will be clear the next day</i>.” Why? Because the storm will not pass to +the westward, covering the sun and continuing, how strong soever the wind +may be from the east; and because it is passing, and will continue to pass +off to the eastward, leaving the sky clear. <i>The easterly wind will stop +as soon as the storm clouds have passed, and it will fall calm, or the +wind will “come out” from the westward.</i></p> + +<p>So, too, when the clouds are dark in the west in the morning, and the sun +rises clear, but “<i>goes into a cloud</i>,” as it is expressed, you say that +it will rain. And if the clouds are dense this generally proves true; +because there is a storm or shower approaching from the west, and passing +over to the east, the western edge of whose advance condensation has met +the sun in his coming, and obscured him from your vision.</p> + +<p>When, too, it has been storming, and lights up in<span class="pagenum"><a name="Page_48" id="Page_48">[Pg 48]</a></span> the N. W. you say it +will clear off; the N. W. wind will blow all the clouds away. It is, +indeed, generally true that when it so lights up it is about to clear off; +although it sometimes shuts down again, in consequence of the approach of +another storm from the westward, following closely behind the one which is +passing off. It is a great mistake, however, to suppose the N. W. wind +blows away the clouds. Watch the smooth stratus rain cloud at its lower +edge, where the clear sky is seen, and you will see that it is moving on +steadily to the N. E., in obedience to the laws of its current, and will +do so, even when its retreating edge has passed up to the zenith, and down +to the S. E.</p> + +<p>The storm uncovers us from the N. W. by the contraction of its width, <i>or</i> +because it has a <i>southern lateral extension</i> and <i>dissolution</i>, and not +by being blown away by the N. W. wind; although that wind, by its peculiar +fair-weather clouds, may be, perhaps, observed beneath, ready to follow +its retreating edge.</p> + +<p>Again, when it has been clear all day, and the sun sets in a bank of +cloud, you say—“<i>it will rain to-morrow, the sun did not set clear</i>,” and +unless that bank is a thunder cloud, merely, which will pass over or by +you, with or without rain, before morning, it is generally true that it +will. The bank will prove the eastern edge of an approaching storm.</p> + +<p>From these generally admitted and understood facts, you may know that +storms pass from the west to the east.</p> + +<p><span class="pagenum"><a name="Page_49" id="Page_49">[Pg 49]</a></span>This proposition is also proved by all the investigations of storms, which +have taken place since the settlement of this country. Storms of great +severity attract particular attention, and are said to “back up” against +the wind, because they are observed to commence storming first at the +westward, although the wind is from the eastward. Doubtless you recollect +many such instances recorded in the newspapers. No season occurs without +such notices.</p> + +<p>Many storms have been investigated by Mr. Redfield, for the purpose of +sustaining his theory. Many others by Professor Espy, to sustain his. One +by Professor Loomis, with great research and ability—and some by others, +accounts of all which have been published; and every one yet investigated, +north of the parallel of 30°, has been shown to pass from a westerly to an +easterly point.</p> + +<p>So, too, we may know it from analogy. The laws of nature are uniform. +There is a great end to be accomplished, <i>viz.</i>: the distribution of forty +inches of water, at regular intervals, over a large extent of country. The +rivers are to return, and the clouds are to drop fatness, and seed time +and harvest are not to cease. It is to be done and is done, by means of +storms and showers, and pursuant to general laws, as immutable as the +result. Most of these storms and showers, it has been found, and may be +observed, move from the westward to the eastward. Then we may know, from +analogy, that they do so in obedience to a general, uniform law; and so I +might say with confidence, if our inquiry stopped<span class="pagenum"><a name="Page_50" id="Page_50">[Pg 50]</a></span> here, it will ever be +found by those who may hereafter examine them.</p> + +<p>But, 2d. There is a current in the atmosphere, all over the continent +north of the N. E. trades, but in great volume over the United States, +east of the meridian of 105° W. from Greenwich—varying in different +seasons, and upon different parallels, and flowing near the earth, when no +surface wind interposes between them. In the vicinity of New York, the +usual course of this current is from about W. S. W. to E. N. E. In the +western and south-western portion of the United States, it is, doubtless, +more southerly—varying somewhat according to the season—and in other +sections varies in obedience to the general law of its origin, and +progress.</p> + +<p>I have observed its course in many places, between the parallels of 38° +and 44° N. <i>This current comes from the South Atlantic Ocean.</i> It is our +portion of the aerial current, which flows every where from the tropics +toward the poles, to which I have already alluded in connection with the +distribution of heat. <i>It brings to us the twenty inches of rain which we +lose by the rivers, and by the westerly winds, which carry off a portion +of the local moisture of evaporation, and its action precipitates the +remaining portion of that moisture. It spreads out over the face of our +country, with considerable, but not entire uniformity. All our great +storms originate in it, and all our showers originate in or are induced +and controlled by it.</i></p> + +<p><i>From the varied action, inherent or induced, of this current, most of our +meteorological phenomena, whether<span class="pagenum"><a name="Page_51" id="Page_51">[Pg 51]</a></span> of wet or dry, or cold or warm weather, +result</i>; and a thorough knowledge of its origin, cause, and the reciprocal +action between it and the earth, is essential to a knowledge of the +“<i>Philosophy of the Weather</i>.”</p> + +<p>Let us then go down to the “chambers of the south,” to the inter-tropical +regions, of which we have said something in connection with a notice of +Southern Mexico, and see where, and how this great aerial current +originates.</p> + + +<p> </p><p> </p> +<hr style="width: 50%;" /> +<p><span class="pagenum"><a name="Page_52" id="Page_52">[Pg 52]</a></span></p> +<h2><a name="CHAPTER_IV" id="CHAPTER_IV"></a>CHAPTER IV.</h2> + +<p>Between the parallels of 35° north latitude, and 35° south +latitude—changing its location within this limit at different seasons of +the year—encircling the earth, and covering about one-half of its +area—we find the trade-wind region. In this region are the simple and +uniform arrangements, which extend every where, and produce all the +atmospheric phenomena. In the center of it we find that movable belt of +continual or daily rains, and comparative calms, particularly <i>near its +center</i>, about four hundred and fifty miles in width upon the Atlantic, +and over Africa, and the eastern portions of the Pacific, and something +more over South America and the West Indies, the western portion of the +Pacific and the Indian Ocean, to which we have already alluded. This belt +of rains and calms follows the trades and sun, in their transit north and +south, from one tropic to the other—its width and extension depending +upon the volume of trade-winds existing on the sides of it. Its southern +edge, when the sun is at the southern solstice, extends to 7° south in the +Atlantic, to 10° south in the Indian Ocean, and still further, probably, +over South America: on this point I do not pretend to be accurate, for +accuracy is not essential. When<span class="pagenum"><a name="Page_53" id="Page_53">[Pg 53]</a></span> the sun is at the northern solstice the +southern edge is carried up as far as 12° north, over the Atlantic, and +still further over the northern portions of South America, the West +Indies, and Mexico. It travels, therefore, from south to north, over from +twenty to forty degrees of latitude. The presence of this belt of rains +over any given portion of the inter-tropics, gives that portion its rainy +season, and its absence, as it moves to the north, or the south, gives the +portion from which it has moved, its dry season. It passes in its transit +twice each year over some portions of the country, Bogota, for instance, +and two corresponding rainy and dry seasons result. Its presence, and +character, and movements, are as fixed and regular, over from twenty-five +to forty degrees of the earth’s surface, <i>and all around it</i>, as the +presence and movements of the sun over the same area.</p> + +<p>At the northern edge of this movable belt of rain, and extending in some +places, particularly in the Pacific Ocean, north about 20°, or about one +thousand four hundred miles, and in other places a less distance, the N. +E. trade winds prevail, blowing toward and into it from N. N. E., N. E., +and E. N. E., averaging about N. E. At the south line of this belt of +rains, extending south from twenty-five to thirty degrees, or from sixteen +hundred to two thousand miles, the S. E. trades blow toward and into it, +from the S. E., S. S. E., or E. S. E., averaging about S. E. Of course the +northern limit of the N. E. trades travels north and south with the belt +of rain, toward which it blows; and so the southern limit of the S. E.<span class="pagenum"><a name="Page_54" id="Page_54">[Pg 54]</a></span> +trades travel in like manner with the rainy belt, or rather, to speak with +entire accuracy, the belt of rain moves with the trades, and the trades +follow the verticality of the sun. The following diagrams exhibit +approximately, and with sufficient accuracy for illustration, the +situations of the rainy belt and the trades, when at their northern and +southern limit, as well as the manner in which it must give certain +localities two rainy seasons each year, in its transit north and south.</p> + +<p>At the northern and southern limits of the trade-winds, and extending from +them to the poles, are found the variable winds and irregular +extra-tropical rains, all over the earth, which are shown by the shading +on the maps. This line of extra-tropical rains descends to the south, +following the retreating trades as they descend in our winter, and recedes +north before the trades when they return in spring and summer, so that at +the outer limit of the trades respectively, toward the poles, the line of +extra-tropical rains will be found, receding or following that limit, as +the trades pass up and down with the sun. From the north pole to the +northern limit of the N. E. trade-winds, wherever found, whether at 38° +north latitude, as in some places in summer when the sun is at the tropic +of Cancer; or whether at 20° to 30° north latitude, as in our winter, when +the sun is at the tropic of Capricorn; the extra-tropical rains prevail. A +state of things precisely similar exists between the south pole and the +southern limit of the S. E. trades. Between this northern limit of the +<span class="pagenum"><a name="Page_55" id="Page_55">[Pg 55]</a></span>N. E. trades and the northern line of the inter-tropical belt of +rains, wherever situated (with two exceptions, to which we have alluded +and shall allude again), there is, for the time being, a dry season; and a +like dry season between the southern line of the belt of rains and the +southern limit of the S. E. trades. We have, therefore, extending around +the earth, a belt of daily tropical rains, near the center,—two belts of +drought which are mainly trade-wind surfaces, one on each side of the +central rainy belt,—extending to the outward limits of the trades and the +line of extra-tropical rains; and these rainy and dry belts, moving up and +down after the sun, a distance of from twenty to forty degrees of +latitude, each year.</p> + +<p> </p> +<p><span class="pagenum"><a name="Page_56" id="Page_56">[Pg 56]</a></span></p> +<p class="center"><strong>Fig. 10.</strong></p> +<div class="figcenter"><img src="images/i0078.jpg" alt="" /></div> +<p class="center"><strong>IN SUMMER.</strong></p> +<p><span class="pagenum"><a name="Page_57" id="Page_57">[Pg 57]</a></span> </p> +<p><span class="pagenum"><a name="Page_58" id="Page_58">[Pg 58]</a></span></p> +<p class="center"><strong>Fig. 11.</strong></p> +<div class="figcenter"><img src="images/i0080.jpg" alt="" /></div> +<p class="center"><strong>IN WINTER.</strong></p> +<p> </p> + +<p><span class="pagenum"><a name="Page_59" id="Page_59">[Pg 59]</a></span>Such are the <i>main</i> phenomena, <i>at the surface</i>, in the trade-wind region. +Ascending a step higher in the atmosphere, we find, above the +surface-trades, a counter-trade, running, not in the opposite direction, +but at right angles, or nearly so. The counter-trade which issues from the +northern side of the rainy belt, running to the N. W. or W. N. W., and the +counter trade which issues from the southern side, running to the S. W. or +W. S. W., varying, as the trades do in direction in different localities. +These counter-trades are continuations of the surface trades, which, +ascending in their course, have threaded their way through the opposite +trade in the rainy belt, and are continuing on at the same angle, and in +the same direction at which they blew upon the surface, and in obedience +to the same law. This is apparent from several considerations.</p> + +<p><span class="pagenum"><a name="Page_60" id="Page_60">[Pg 60]</a></span>1st. They issue at the same angle, and over the top of the surface trades. +In the West Indies and elsewhere, this has been ascertained and proved by +the course of the storms, and the rotation of their surface winds, and +observation.</p> + +<p>2d. We can not suppose the N. E. trade to be reflected, and turn back over +itself at a right angle. That would be impossible, even if there were a +wall of solid material there for it to blow against. Air is a peculiar +fluid, and it stratifies with astonishing ease. He who supposes that a +current of air put in motion can be turned aside by another current, or by +the atmosphere at rest, or can be made to mingle, is mistaken. It will +stratify, and force itself onward through the adjacent and opposing +atmosphere, and in a right line. I have observed some remarkable instances +of this character.</p> + +<p>3d. The cause which operates to produce the surface trades, still operates +upon the current to carry it over into the other hemisphere; a +counter-trade, as we shall see. It is impossible, therefore, to believe +that the surface-trades as they arrive at the belt of rains and calms, +turn at a right angle, or at any angle, and return: and impossible to +doubt that they pass through each other in this belt, and out at the +opposite side, as upper currents, at the same angle at which they entered. +Of course the N. E. trade of the Atlantic becomes the N. E. counter-trade +of South America, carrying their storms in a S. W. direction, and the S. +E. trade of the Atlantic the S. E. counter-trade of the West Indies, +carrying<span class="pagenum"><a name="Page_61" id="Page_61">[Pg 61]</a></span> all their storms in a N. W. direction; and what is true of them +is true of the trade winds <i>every where, all over the globe, over the land +and over the sea</i>.</p> + +<p>Doubtless here some one will say, our upper current is a S. W. current. +True, the S. E. trade which enters the belt of rains, and issues out on +the north, a S. E. upper current or counter-trade, keeps that course until +it arrives at the northern limit of the surface trade, when, in <i>obedience +to another law</i>, which we shall notice, it gradually <i>decends near the +surface, curves to the eastward</i>, and becomes <i>the S. W. current which +passes over us</i>. And so we have the S. E. trade-wind of the South +Atlantic, with its moisture, warmth, electricity, and polarity, over, and +perhaps sometimes around us, dropping the electric rain which makes glad +our fields; giving us, when not prevented by other conditions, the balmy +air of spring, the Indian summer of autumn, and the mild mitigating +changes of winter; and thus, <i>our rivers, which run into the sea, return +to us again</i>.</p> + +<p>But let us go back to the trade-wind region—the region of regularity and +uniformity—and examine somewhat more attentively its features, that we +may more fully understand the character of this counter-trade.</p> + +<p>Here are 60° at least of the 180° of the earth’s surface, and at its +largest diameter, covered in the course of the year, and of their travels, +by the trade-winds at the surface, the counter-trades above, and the belt +of rains and comparative calms, formed by the action of the opposite +trades, as they thread<span class="pagenum"><a name="Page_62" id="Page_62">[Pg 62]</a></span> their way through each other, to assume the +relation of counter-trades. Truly the magnitude, simplicity, and +regularity of this machinery are most wonderful.</p> + +<p>There are, however, some <i>apparent</i> anomalies which deserve attention. +Here are most distinctly marked the <i>rainy</i> and <i>dry seasons</i>, existing +side by side. Here are the <i>rainless portions</i> of the earth, already but +briefly alluded to; here the <i>monsoons</i>, and another peculiarity, <i>viz.</i>: +the <i>gathering of the counter-trades</i> upon the western sides of the two +great oceans, into two <i>aerial currents of greater volume</i>, <i>analogous</i> +somewhat to the two <i>gulf streams</i> of those oceans. Let us examine these +anomalies.</p> + +<p>The rainy and dry seasons depend, as we have seen, upon the transit north +and south of the rainy belt, or belt of comparative calms. Wherever this +belt may happen on any given day to be situated, each side of it the +trades prevail, it is dry, the earth is parched, and vegetation withers. +These changes are graphically described by Humboldt in his “Views of +Nature,” as they occur on the northern portions of South America, as +follows: “When, beneath the vertical rays of the bright and cloudless sun +of the tropics, the parched sward crumbles into dust, then the indurated +soil cracks and bursts, as if rent asunder by some mighty earthquake. The +hot and dusty earth forms a cloudy vail, which shrouds the heavens from +view, and increases the stifling oppression of the atmosphere; while the +east wind (<i>i. e.</i> trade-wind), when it blows over the long heated soil, +instead of cooling, adds to the burning glow.</p> + +<p><span class="pagenum"><a name="Page_63" id="Page_63">[Pg 63]</a></span>“Gradually, too, the pools of water, which had been protected from +evaporation by the now seared foliage of the fan-palm, disappear. As in +the icy north animals become torpid from cold, so here the crocodile and +the boa-constrictor lie wrapped in unbroken sleep, deeply buried in the +dried soil. Every where the drought announces death, yet every where the +thirsty wanderer is deluded by the phantom of a moving, undulating, watery +surface, created by the deceptive play of the reflected rays of light (the +mirage). A narrow stratum separates the ground from the distant +palm-trees, which seem to hover aloft, owing to the contact of currents of +air having different degrees of heat, and therefore of density. Shrouded +in dark clouds of dust, and tortured by hunger and burning thirst, oxen +and horses scour the plain, the one belowing dismally, the other with +outstretched necks snuffing the wind, in the endeavor to detect, by the +moisture in the air, the vicinity of some pool of water not yet wholly +evaporated.</p> + +<p>“Even if the burning heat of day be succeeded by the cool freshness of the +night, here always of equal length, the wearied ox and horse enjoy no +repose. Huge bats now attack the animals during sleep, and vampyre-like +suck their blood; or, fastening on their backs, raise festering wounds, in +which mosquitos, hippobosces, and a host of other stinging insects, burrow +and nestle. Such is the miserable existence of these poor animals, when +the heat of the sun has absorbed the waters from the surface of the +earth.</p> + +<p><span class="pagenum"><a name="Page_64" id="Page_64">[Pg 64]</a></span>“When, after a long drought, the genial season of rain arrives, the scene +suddenly changes. The deep azure of the hitherto cloudless sky assumes a +lighter hue. Scarcely can the dark space in the constellation of the +Southern Cross be distinguished at night. The mild phosphorescence of the +Magellanic clouds fades away. Even the vertical stars of the +constellations Aquila and Ophiuchus, shine with a flickering and less +planetary light. Like some distant mountain, a single cloud is seen rising +perpendicularly on the southern horizon. Misty vapors collect and +gradually overspread the heavens, while distant thunder proclaims the +approach of the vivifying rain. Scarcely is the surface of the earth +moistened, before the teeming steppe becomes covered with Killingiæ, with +the many-panicled Paspalum, and a variety of grasses. Excited by the power +of light, the herbaceous Mimosa unfolds its dormant, drooping leaves, +hailing, as it were, the rising sun in chorus with the matin song of the +birds, and the opening flowers of aquatics. Horses and oxen, buoyant with +life and enjoyment, roam over and crop the plains. The luxuriant grass +hides the beautiful and spotted jaguar, who, lurking in safe concealment, +and carefully measuring the extent of the leap, darts, like the Asiatic +tiger, with a cat-like bound on his passing prey.”</p> + +<p>Such is Humboldt’s description of the dry season on the Orinoco, and the +return of the belt of rains from the south.</p> + +<p>Again, within this trade-wind region are the<span class="pagenum"><a name="Page_65" id="Page_65">[Pg 65]</a></span> <i>rainless countries</i>. These +are portions of the earth which the equatorial rainy belt does not ascend +far enough north in summer to cover, nor does the southern edge of the +extra-tropical regular rains descend, in winter, far enough south to cover +them, and where, of course, rain seldom, if ever, falls. Such are the +central parts of the Desert of Sahara, Egypt, Arabia, portions of +Affghanistan, Beloochistan, and the western parts of Hindoostan, to the +north of the inter-tropical belt, and a similar state of things exists +south of the equator in parts of South America, Africa, and New Holland, +although upon a comparatively small surface.</p> + +<p>Again, another anomaly is the gathering of the trade winds into greater +volumes, on the westerly side of the great oceans, and the consequent +carrying of the equatorial rainy belt up to the region of extra-tropical +rains, on the eastern side of the great continents of Asia and North +America, and the peculiar liability of these aerial gulfs to hurricanes +and typhoons. Such an aerial gulf gathers over the Caribbean Sea, and the +West Indies. Passing across the Gulf of Mexico, it enters over Texas, and +Louisiana, and the other southern states; its western edge passing north +in autumn and winter, on the eastern side of the highlands of Western +Texas, New Mexico, and the Great Desert; curving, as all counter-trades +do, to the eastward as soon as it passes the limit of the N. E. trades, +and spreading out over our favored country, leaving the evidence of its +pathway in the greater quantities of rain, which fall annually upon<span class="pagenum"><a name="Page_66" id="Page_66">[Pg 66]</a></span> its +surface. This gathering deprives a portion of the Atlantic, north of the +tropics, of its share of the counter trade, and there, as every where, +where the volume of counter-trade is small, storms and gales are +infrequent, and of less force, and comparative calms prevail. That portion +of the Atlantic has long been known as “the horse latitudes,” a name given +to it by our Yankee sailors, because, there, in former times, the +old-fashioned, low-decked, flat-bottomed, horse-carrying craft of New +England, bound for the West Indies, often floundered about in the calms +and baffling winds, until their animals perished for want of water, and +were thrown overboard. Lieutenant Maury, in his most praiseworthy and +exceedingly useful investigation of “The Winds and Currents of the Ocean,” +has defined the situation of these calms and baffling winds at different +seasons—for they move up and down, of course, with the motion of the +whole machinery—and enabled navigators to avoid them, by running <i>east</i> +before they attempt to make <i>southing</i>; and very materially shortened the +voyages to the equator.</p> + +<p>A like gathering, in volume, of the S. E. trade, on the western side of +the Pacific, enters over Asia, and covers China and Malaysia, extending, +in its western course, nearly as far as the western edge of Hindoostan. In +this concentrated volume of counter-trade, and owing to its concentrated +action, form and float the typhoons of the China Sea, and of the Bay of +Bengal; and to this anomalous aerial gulf stream, the S. E. portions of +Asia, from the western desert<span class="pagenum"><a name="Page_67" id="Page_67">[Pg 67]</a></span> of Hindoostan, to the eastern portion of +China, north of the rainy belt, owe their great supply of moisture and +fertility, and their peculiar climate. The western line of this volume of +counter-trade is marked by the eastern portion of the rainless region of +Beloochistan, and the north-western deserts of India, as the western edge +of our concentrated volume of counter-trade, is marked by the arid plains +of northern Mexico, western Texas, and New Mexico. On the south of the +equatorial rainy belt, there is no corresponding aerial gulf of equal +volume, as there is no corresponding gulf stream of equal magnitude. On +the western side of the Indian Ocean we find a gathering of the N. E. +trades from the Bay of Bengal and the Indian Ocean, in which form and +travel the hurricanes which prevail—traveling to the southward and +westward—about the Isle of France or Mauritius; and the lagullus oceanic +current, which runs down to the S. W. toward the Cape of Good Hope. But +the extension of South America to the eastward, under, or just south of +the N. E. trades, does not permit the formation of such a concentrated +volume on the western side of the Atlantic, nor is the strength or +regularity of the N. E. trades, on that ocean, equal to those of the S. E.</p> + +<p>Nor is the magnetic intensity on the eastern and middle portions of the +Pacific, sufficient to produce such a concentration, in large volume, +there. The trades over that ocean, therefore, curve without concentration, +except a partial one, over the western groups of Polynesia, which the +Asiatic line of <span class="pagenum"><a name="Page_68" id="Page_68">[Pg 68]</a></span>magnetic intensity approaches and where hurricanes are +sometimes found, until we arrive near the eastern line of magnetic +intensity, on the eastern side of Asia. We shall, hereafter, have occasion +to follow the anomalous concentrated volumes of the S. E. counter-trade, +of the northern tropic, on the western side of the great oceans, in +explanation of some of the phenomena which we find north of the trade-wind +region. Suffice it here to add, that if it were not for the concentration +of these counter-trades, on the western side of the great oceans, the +rainless region between the parallels of 20° and 30° would encircle the +earth; and China and the Eastern United States would have a distinctly +marked rainy and dry season, as have California, the Barbary States, +Syria, Persia, and other countries which lie north of the rainless region, +within the summer range of the N. E. trades, but also within the winter +descending range of the belt of extra-tropical rains.</p> + +<p>Another anomaly which we find in the trade-wind region, is the monsoon. +There are several of them, but they are found, in the greatest strength +and regularity, in the Indian Ocean. Another, defined by the +investigations of Maury, is found on the west coast of Africa, extending +out over the Atlantic. Another prevails on the western coast of South and +Central America. The etesian winds of the Mediterranean are but the N. E. +trades, whose northern limit is carried up in summer, by the transit of +the connected machinery, to the north, over that sea. The N. E. and S. E. +monsoons, so called, of the Indian Ocean,<span class="pagenum"><a name="Page_69" id="Page_69">[Pg 69]</a></span> are but the regular trades, +blowing when the belt of rains is absent, as they do all over the globe. +The N. W. monsoon, south of the equator, in the vicinity of New Holland; +the S. W. monsoon which blows from the Arabian Sea, in upon Hindoostan; +the S. W. monsoon of the Atlantic, south of the Cape De Verde Islands; and +the variable west monsoon winds of the west coast of Southern and Central +America, and Southern Mexico (known under several different names, but +chiefly by that of Tapayaguas), are all that deserve attention as such.</p> + +<p>At first sight they appear to be anomalies, but the facts declare their +character with perfect certainty. First, they are not continuous, like the +trades, but <i>prevailing</i> winds, and are <i>storm winds</i>; <i>they always blow +toward a region</i>, <i>or portion of the ocean</i>, <i>covered at the time by +clouds and falling weather</i>.</p> + +<p>Second, they do not blow upon, or toward, heated surfaces of land or +water—<i>i. e.</i>, toward the dry and parched surfaces, where the dry season +prevails, or from adjoining cold waters on to warm surfaces, but toward +the land or water <i>situated under the rainy belt</i>. They are therefore +incident storm winds, (as our easterly winds are incident storm winds) of +the rain clouds of the tropics. They blow in upon the land, under the belt +of rains, while that belt with its daily cloud, and inducing electric +action, is over it, and follow that belt in its transit north and south. +They blow from the warm south polar current of the Atlantic, which flows +N. W. from the coast of Africa, toward the inshore north polar current, +which is<span class="pagenum"><a name="Page_70" id="Page_70">[Pg 70]</a></span> there flowing south, but under the belt of rains. In the Indian +Ocean they blow from the center of that ocean, and the Arabian Sea, toward +the belt which hangs over Hindoostan, from the S. W.; and when the rainy +belt travels south they still blow toward, and under it, from the Indian +Ocean, but of course from the N. W. The heated character of the waters of +the Indian Ocean and Arabian Sea, which receive no polar currents, but +heated waters from the Persian Gulf, and from rivers which flow into the +Bay of Bengal over the heated plains of a tropical country, explain this. +So, too, the monsoon of the Atlantic Ocean, does not blow north of the +Cape De Verde Islands,—where the heated surface of Sahara, burning with +the rays of a vertical sun, has a temperature sometimes ranging from one +hundred and forty to one hundred and sixty degrees—but remains under the +rainy belt, drawn from the heated waters which flow up from the South +Atlantic, and travels north as the rainy belt travels north in summer, and +south to the Gulf of Guinea, as that travels south in winter. The same is +true of the Pacific monsoon, the Tapayaguas, the least marked of all, +which blows in during the rainy season upon the west coast of Southern +Mexico, and of Southern and Central America. They are all incident rain or +storm winds, blowing in upon the land, or on to a colder surface of +different polarity, <i>during the rainy season</i>; and if it were possible to +catch one of our north-easters, in its passage over our country to the +eastward, and anchor it to the Alleghanies, “paying out” so to have it +reach in part over<span class="pagenum"><a name="Page_71" id="Page_71">[Pg 71]</a></span> the Atlantic, and keep it there in operation six +months, we should have a continual easterly wind under it; a <i>monsoon</i> +more strongly marked than the monsoons of the Indian, or Atlantic Oceans. +<i>The received theory in relation to them is a fallacy.</i></p> + +<p>Recapitulating, then, all the phenomena, we have,—<i>Surface-trades</i>, +blowing toward the center, passing through each other, and continuing on +as upper or counter-trades; a <i>belt of rains</i>, with calms near the center, +formed by the trades where they meet and pass through each other, which +travels with them north and south following the sun; <i>two belts of +drought</i>, following the belt of rains and the trades, and followed by the +<i>extra</i>-tropical line of rains, as it travels with the trades and the +rainy belt, leaving a part of the earth which the equatorial rainy belt +does not travel far enough north, nor the extra-tropical line of rains far +enough south to cover, and which is consequently a <i>rainless region</i>; <i>the +monsoons</i>, which are but incidents of the rainy belt, and the <i>gathered +volumes</i> of counter-trade, on the west of the two great oceans, which +usurp the place of the N. E. trades, carrying the rainy belt up to the +region of extra-tropical rain, and preventing the rainless region from +encircling the earth.</p> + +<p>Upon <i>what cause</i> do these great central phenomena, so vast, so regular, +so wonderful, depend? What is the <i>motive power</i> of this connected +atmospheric machinery, whose action and influence extend over the entire +globe?</p> + +<p>“<i>Heat, heat</i>,” say the text books, the Professors,<span class="pagenum"><a name="Page_72" id="Page_72">[Pg 72]</a></span> the votaries of +meteorology. “All these phenomena are owing to the heat of the sun. It +heats the ocean and the earth—the air is thereby heated and rises, the +cold air rushes in from below, then the ascended current rolls off each +way at the top toward the pole, acquiring a westerly motion from the +rotation of the earth, slipping away from under it, and a different, +<i>viz.</i>: an easterly motion, after reaching the latitude of 30°, from the +<i>same rotation</i>; and all the winds and disturbances of the atmosphere are +produced in the same way. They are produced by the action of heated +surfaces upon the adjacent atmosphere.”</p> + +<p>This is the great theory of meteorologists, by which they attempt to +account for the various atmospherical disturbances, of both tropical and +extra-tropical regions.</p> + +<p>The whole theory is a fallacy—it will not stand the test of a careful +examination. The bases of the theory, which are assumed to be facts, are +not so. The agent has not the power claimed for it. A heated surface, +alone, never caused any considerable ascending current, or if it did, +never produced a mile of wind. I repeat it, the theory and all incidental +ones—the thousand explanatory and modifying theories, and +hypotheses—<i>the whole system</i>—is without foundation in fact, and will +not bear a critical examination.</p> + +<p>Let us see if this language is stronger than the facts will warrant.</p> + +<p>The theory assumes that both the land and water, under this central belt, +where the air is <span class="pagenum"><a name="Page_73" id="Page_73">[Pg 73]</a></span>supposed to be rising are <i>materially hotter</i> than the +land and ocean are on <i>either side of it</i>. Now, how much hotter are the +air and the land under the belt of rains and calms, upon Hindoostan, or +Africa, or South America, where the former is supposed to be acquiring +heat and expansion so rapidly, and to be ascending, than under, and in the +dry belts on either side? None; it is cooler by the thermometer—<i>much +cooler</i>.</p> + +<p>The central belt of rains in midsummer over Africa, extends up as far as +17° north latitude, and perhaps further. North of this line over the whole +surface of the desert, the Barbary States, a part of the Mediterranean, +and some portion of Italy, the dry season extends, and from the entire +surface the N. E. trade blow into the central belt.<small><a name="f1.1" id="f1.1" href="#f1">[1]</a></small> Over the desert +they all pass. Now this desert is a sea of sand, under a vertical sun, +intensely heated, blistering the skin with which it comes in contact, and +often acquiring a temperature of 150° to 160° of Fahrenheit. Under the +central belt of rains neither the earth nor air exceed the temperature of +84°. And yet the hot air of the desert does not ascend, but blows into +this cooler central belt; and when it is felt as it blows off the western +coast by the mariner, or even in Guinea, when the belt of rains has gone +south in winter, as it often is as the <i>harmattan</i>, it is suffocating and +intolerable. There, then, not only is it untrue, that the land and the air +over it under the rainy belt are hotter, but it is true that intensely<span class="pagenum"><a name="Page_74" id="Page_74">[Pg 74]</a></span> +heated air blows horizontally from the Desert of Sahara. Nay, as it will +appear in the sequel, this hottest of all surfaces not only can not have a +vortex, but it can not induce a monsoon, and scarcely a sea breeze. The +same is true in a great degree of the surface, and the air over it, on +either side of the supposed vortex of the rainy belt upon South America. +See the description of Humboldt, already given, where the thermometer +stood as high as 115° of Fahrenheit in the shade, while the N. E. winds, +the regular trades, were blowing over the land. And it is equally true of +Arabia, and indeed of every portion of the earth. There is not a spot upon +the globe where the land and the air are cooler <i>by the side</i> of the +central belt of rains, than <i>under it</i>. <i>And the opposite is true every +where upon the land.</i></p> + +<p>How much hotter is the ocean and air under this supposed vortex? But +little hotter than they are on the side where the sun is not vertical, +<i>and none on the other</i>. Let us be a little more particular. The +temperature of the Atlantic under the belt of rains in our winter, and on +the south of the belt at the latitude of 3° south, and down to 9° or more +south, is 82°. The air may range a degree, or possibly two, higher than +the water at either point. On the north this difference is from nothing at +the meeting of the trades and belt of rains, to about 4° at their northern +limit. This is too <i>trifling</i> to be worth one moment’s consideration. It +is less, far less than the difference between the water and air of the +Gulf Stream which runs along our coast, and the adjoining<span class="pagenum"><a name="Page_75" id="Page_75">[Pg 75]</a></span> waters and air +over them. While on the south side of the belt of rains the <i>difference is +actually against the theory</i>—and the same state of things is reversed in +summer, when the sun is vertical at the north.</p> + +<p>From the log of an intelligent shipmaster, found in the wind and current +charts of Lieutenant Maury, I abridge the following, which will illustrate +this. Captain Young in February, found the N. E. trades at about 17° north +latitude, with the water at 75° and air at 76°, trade-wind N. E.</p> + +<table border="0" cellpadding="0" cellspacing="5" summary="charts"> +<tr><td> </td><td class="center">At</td> + <td>12° 16′</td> + <td>the water was</td> + <td>75°</td> + <td>the air</td> + <td>76°</td> + <td>wind</td><td>N. E.</td></tr> +<tr><td>Feb.</td><td class="center">22nd.</td> + <td>9° 49′</td> + <td align="center">"</td> + <td>76½°</td> + <td align="center">"</td> + <td>77°</td> + <td align="center">"</td><td>N. E.</td></tr> +<tr><td align="center">"</td><td class="center">23d.</td> + <td>7° 13′</td> + <td align="center">"</td> + <td>78°</td> + <td align="center">"</td> + <td>78°</td> + <td align="center">"</td><td>N. E.</td></tr> +<tr><td align="center">"</td><td class="center">24th.</td> + <td>no obs.</td> + <td align="center">"</td> + <td>79½°</td> + <td align="center">"</td> + <td>79°</td> + <td align="center">"</td><td>N. E., E. S. E. rain.</td></tr> +<tr><td align="center">"</td><td class="center">25th.</td> + <td>3° 10′</td> + <td align="center">"</td> + <td>81°</td> + <td align="center">"</td> + <td>83°</td> + <td align="center">"</td><td>E. S. E. rain.</td></tr> +<tr><td align="center">"</td><td class="center">26th.</td> + <td>no obs.</td> + <td align="center">"</td> + <td>82°</td> + <td align="center">"</td> + <td>82°</td> + <td align="center">"</td><td>S. E. to E. S. E. hazy, rain & sqs.</td></tr> +<tr><td align="center">"</td><td class="center">27th.</td> + <td>2° 24′</td> + <td align="center">"</td> + <td>82°</td> + <td align="center">"</td> + <td>82°</td> + <td align="center">"</td><td>calm, with rain.</td></tr> +<tr><td align="center">"</td><td class="center">28th.</td> + <td>no obs.</td> + <td align="center">"</td> + <td>82°</td> + <td align="center">"</td> + <td>82°</td> + <td align="center">"</td><td>calm rain.</td></tr> +<tr><td align="center">March</td><td class="center">1st.</td> + <td>0° 29′</td> + <td align="center">"</td> + <td>82°</td> + <td align="center">"</td> + <td>82°</td> + <td align="center">"</td><td>E. S. E. sqs. rain.</td></tr> +<tr><td align="center">"</td><td class="center">2nd.</td> + <td>1° 27′ S. L.</td> + <td align="center">"</td> + <td>82°</td> + <td align="center">"</td> + <td>82°</td> + <td align="center">"</td><td>S. E. sqs. rain.</td></tr> +<tr><td align="center">"</td><td class="center">3d.</td> + <td>2° 44′</td> + <td align="center">"</td> + <td>82°</td> + <td align="center">"</td> + <td>83°</td> + <td align="center">"</td><td>S. E. & S. S. E. weather settled.</td></tr> +<tr><td align="center">"</td><td class="center">4th.</td> + <td>4° 17′</td> + <td align="center">"</td> + <td>82°</td> + <td align="center">"</td> + <td>83°</td> + <td align="center">"</td><td>S. S. E. & S. E. fair weather.</td></tr> +<tr><td align="center">"</td><td class="center">5th.</td> + <td>6° 08′</td> + <td align="center">"</td> + <td>82°</td> + <td align="center">"</td> + <td>84°</td> + <td align="center">"</td><td>S. E. fair wthr.</td></tr> +<tr><td align="center">"</td><td class="center">6th.</td> + <td>8° 08′</td> + <td align="center">"</td> + <td>82°</td> + <td align="center">"</td> + <td>84°</td> + <td align="center">"</td><td>S. E. & E. S. E. fair weather.</td></tr></table> + +<p>Here the air was seven degrees colder at the extreme limit of the N. E. +trades than in the <i>center</i> of the belt of rains, as it is, usually, in +mid-winter, but not in summer. On the other hand, <i>after he left the +region of calms and rains</i>, where the water and air stood with almost +entire uniformity at 82°, on the 3d of March, and for three days +thereafter, during which he was in the S. E. trades with fair<span class="pagenum"><a name="Page_76" id="Page_76">[Pg 76]</a></span> weather, +the water was the same as under the supposed vortex, <i>viz.</i>, 82°, <i>and the +air rose to 83° and 84°</i>! <i>This is demonstration.</i></p> + +<p>I also take from a letter of Lieutenant Walsh to Lieutenant Maury, +relative to the cruise of the “Taney” the following, showing the warmth of +the Gulf Stream compared with the adjacent ocean.</p> + +<div class="blockquot"><p>“We first crossed the Gulf Stream on the 31st of October; we struck +it in latitude 37° 22′, longitude 71° 26′ as indicated by the +temperature of the water, which was as follows:</p> + +<table border="0" cellpadding="0" cellspacing="5" summary="water"> +<tr><td align="right">8</td><td>A.M.</td><td>water at</td><td>surface</td><td>66°</td></tr> +<tr><td align="right">9</td><td align="center">"</td><td align="center">"</td><td align="center">"</td><td>73°</td></tr> +<tr><td>10</td><td align="center">"</td><td align="center">"</td><td align="center">"</td><td>76°</td></tr> +<tr><td>11</td><td align="center">"</td><td align="center">"</td><td align="center">"</td><td>77°</td></tr></table> + +<p>77° was the highest temperature found in crossing at this time.</p> + +<p>Re-crossing it in May, in latitude 35° 30′, longitude 72° 35′, he +found the water as follows:</p> + +<table border="0" cellpadding="0" cellspacing="5" summary="water"> +<tr><td align="right">8</td><td>A.M.</td><td>water at</td><td>surface</td><td>71° 8′</td></tr> +<tr><td align="right">9</td><td align="center">"</td><td align="center">"</td><td align="center">"</td><td>73°</td></tr> +<tr><td>10</td><td align="center">"</td><td align="center">"</td><td align="center">"</td><td>75° 5′</td></tr> +<tr><td>11</td><td align="center">"</td><td align="center">"</td><td align="center">"</td><td>78° 5′</td></tr> +<tr><td>12</td><td align="center">M.</td><td align="center">"</td><td align="center">"</td><td>78° 5′</td></tr></table> + +<p>79° being the highest temperature found.”</p></div> + +<p>The average difference between the temperature of the water of the Gulf +Stream and the adjoining ocean, at the line of division, is about ten +degrees, increasing to more than twenty on approaching the coast, and +within one hundred miles—a far greater difference than is ever found on +the winter side of the inter-tropical rainy belt.</p> + +<p>It is not only not so, then, that the surface of the<span class="pagenum"><a name="Page_77" id="Page_77">[Pg 77]</a></span> ocean is materially +warmer under the belt of rains than the adjoining surface under the +trades, especially on the summer side, but if it were so, the trades would +not be created thereby, any more than upon the Gulf Stream. And the +opposite is true of the land where the line of calms, and rains, and +drought meet, all around the globe. The fact assumed is therefore untrue. +The hottest surfaces, even at the rainless portion, where there is no +vortex, no storm, and no wind but the continual uniform N. E. horizontal +trade-wind, <i>never</i> created, by reason of the heat alone, a mile of wind, +a storm or shower.</p> + +<p>But, again, the belt of calms, where the air is supposed to rise and +create a suction which draws the trades on either side a distance of from +one thousand to two thousand miles, an average of three thousand miles in +all, at least, is not itself, on an average, over five hundred miles in +breadth from north to south. What a wonder of meteorology is here!</p> + +<p>With a breadth of five hundred miles, the rising of the atmosphere is +supposed to be so rapid and of such immense volume that it draws the +surface atmosphere, one thousand to fifteen hundred miles on one side and +two thousand on the other, with a uniform steady velocity of twenty miles +per hour. Is this vast suction found by the unlucky mariner who may be +drawn within the vortex? <i>Not at all.</i> He finds no rapid suction there, +but <i>horizontal currents</i>, not steady, indeed, like the trades, and +sometimes calms <i>at the center</i>, but still the <i>currents are there</i>, and, +<i>except<span class="pagenum"><a name="Page_78" id="Page_78">[Pg 78]</a></span> near the center, there as squalls, showers, and baffling winds +and as monsoons</i>.</p> + +<p>Again, is there at the mouth of this vortex, or as you approach it, an +increased rapidity in the trade corresponding to the magnitude of its +influence? Does the trade become a hurricane as it approaches the spot +where it is to supply the place of that which has suddenly “expanded by +heat, and been forced to rise, boil over, and run off at the top in turn?” +Not at all. It blows gently, even up to the very line of the rainy belt, +and becomes squally and baffling, falls gradually calm near the center, or +changes to a monsoon.</p> + +<p>But, again, the belt of rains is so far from being a belt of calms +strictly, that its monsoons in the Indian, Atlantic, and Pacific Oceans, +at times, extend hundreds of miles out over the ocean. That of the +Atlantic, triangular, with its base resting on Africa, according to +Lieutenant Maury, extends sometimes almost to the coast of South America, +a distance of one thousand miles, and thus under the supposed ascending +vortex. Where is the great uprising suction during the prevalence of this +extensive surface horizontal monsoon beneath it? Manifestly it does not +exist. Nay, that monsoon is blowing from the warm current which sets up +from the Cape of Good Hope toward the Caribbean Sea, and over the cold +north polar current, which runs down between the continent and the Cape de +Verdes. Equally untrue is the presumption that the air rises over heated +portions of the earth elsewhere, and by reason of such heating.<span class="pagenum"><a name="Page_79" id="Page_79">[Pg 79]</a></span> +<i>Perpendicular currents of the atmosphere are rarely seen, never +extensive, or attaining any considerable altitude.</i> I have watched for +them thirty years. I have seen currents of air ascend, with their moisture +condensing as they ascended, and unite with the under surface of a highly +electrified cloud—the advance condensation of a thunder shower—but that +cloud was moving horizontally at a distance of from one to two thousand +feet above the surface of the earth, and did not rise. I have seen patches +of scud rising from the surface during the intervals of a showery and +highly electrified storm, toward, and uniting with, the clouds above, when +very low, as I have seen them approach and unite horizontally; and +doubtless there is a tendency upwards of the wind, created and attracted +by the summer shower, as may be seen in the ascending dust before the +rain, but I have never been able to detect an ascending current, except as +induced and attracted by a cloud above moving horizontally, in the hottest +day or dryest time. None of the clouds of our climate, even when the earth +is heated and parched by a two months’ unbroken drought, can be detected +rising above the strata in which they form. I have watched the cumuli at +such periods when they filled the air, and can assert that they never +rise. The atmosphere moves, invariably, in horizontal strata, and the +whole theory of ascending currents is fallacious.</p> + +<p>But let us look still further at the tropical currents. The true harmattan +of north-western Africa (for the term is sometimes misapplied), hot and +blistering,<span class="pagenum"><a name="Page_80" id="Page_80">[Pg 80]</a></span> generated upon the sand of the desert—why does it blow from +Sahara horizontally, on or over cooler surfaces, following the belt of +rains as a N. E. trade? Why does it not ascend? The sirocco of north +Sahara, the kamsin or chamsin of eastern Sahara, and the simoon of Arabia, +which blow hot and suffocating from those deserts—why do they blow <i>from</i> +heated surfaces and <i>horizontally over</i> cooler ones? Why do they not +ascend? Arabia is surrounded on three sides by seas and gulfs, from which +evaporation is rapid. Her interior deserts are extensive and intensely +hot—why are they rainless? Why do they not have a <i>vortex</i>, a <i>monsoon</i>, +or even a <i>shower</i>? Because there is no such law or action as this theory +supposes. Those winds blow horizontally in obedience to other laws, and +under the control of other and more powerful agents. But further still, +what heating and ascending process is it that makes the variable winds +north of the tropics? that brings in the warm air and fog of the Gulf +Stream upon our <i>snow-clad coast</i>, in mid-winter, to increase the January +thaw? Nay, what heating process is it that disturbs the calms of the polar +regions with fresh breezes and gales, sometimes of the force of 6, when +the <i>sun does not shine</i>, the thermometer is from 20° to 40° below zero, +the <i>earth and sea one frozen surface</i>, and the hardy explorer dressed in +furs, barely lives in his cabin covered by an embankment of snow, and +heated by a stove?</p> + +<p>Gentlemen, meteorologists, it will not do. The theory is unsound; the +assumed facts do not exist.<span class="pagenum"><a name="Page_81" id="Page_81">[Pg 81]</a></span> The whole universe has not an agent, organic +or inorganic, which can play such absurd and inconsistent pranks in the +face of its Creator, as your various and complicated theories assign to +caloric.</p> + +<p>Away with the theory and all its incidental and complicated and mystified +hypotheses, they rest like a pall upon the science;—away with the whole +system, and let us seek some agent whose <i>power</i> and <i>adaptation</i> +correspond with the <i>extent</i>, and <i>simplicity</i>, and <i>magnificence</i> of the +phenomena, and, in some degree, with the <i>power</i> and <i>wisdom of their +Author</i>.</p> + + +<p> </p><p> </p> +<hr style="width: 50%;" /> +<p><span class="pagenum"><a name="Page_82" id="Page_82">[Pg 82]</a></span></p> +<h2><a name="CHAPTER_V" id="CHAPTER_V"></a>CHAPTER V.</h2> + +<p>One, and the principal end attained by the power of the agent, is the +gathering of a volume of atmosphere from, or near, the <i>surface</i> of the +land and sea, so as to ensure its possession of all the moisture of +evaporation which rises from the locality, and the highest degree of +temperature, and from a space ranging from one to two thousand miles in +width, in one hemisphere, and to carry it over into the other. Not over +the top, or upon the top, of the whole mass of atmosphere situated in the +opposite hemisphere—<i>out of reach of all influences from the earth</i>—but +through it, and curving gradually down near to, and within influential +distance of the surface of the earth, soon after it passes the outward +limit of its fellow trade; and to continue the current onward, leaving +portions of it and its heat and moisture on the way, but taking a +considerable volume up and around the magnetic poles—it being impossible +for the entire volume to be thus carried around the poles in consequence +of the diminished circumference of the earth. To this end it is obvious it +must possess <i>polarity</i>.</p> + +<p>Another end to be attained is to combine the moisture of evaporation with +the air, so that the cold<span class="pagenum"><a name="Page_83" id="Page_83">[Pg 83]</a></span> atmosphere through which, or the earth over +which it passes, may not be <i>continually condensing its moisture</i>, and +thereby <i>enveloping the earth in a perpetual mist</i>; but so that it may +part with it at <i>intervals</i>, making <i>cloudy</i> and <i>clear days</i>; and part +with it in <i>portions</i>, so that a <i>regular</i> and <i>necessary supply</i> may be +furnished to the <i>entire hemisphere</i>, even up to the geographical poles. +Is there such an agent? There is, precisely and perfectly adapted to the +ends to be attained, ever there and ever active, and that agent is +<i>magnetism</i>.</p> + +<p> </p> +<p class="center"><strong>Fig. 12.</strong></p> +<div class="figcenter"><img src="images/i0106.jpg" alt="" /></div> +<p> </p> + +<p>The earth is a magnet. It has its magnetic poles, and they are distinct +from its geographical ones; and there are two in each hemisphere. They are +situated from 17° to 19° distant from the geographical poles; and ours is +not far from longitude 97° W. from Greenwich, and 71° north latitude. +Navigators have gone north and north-west of it, and found its situation +by the declination of the needle. From these poles, lines of magnetic +intensity extend to the opposite and corresponding pole of the other +<span class="pagenum"><a name="Page_84" id="Page_84">[Pg 84]</a></span>hemisphere, and upon or near those lines the needle points north without +variation; and toward these lines of no variation the needle every where, +on either side declines. The foregoing diagram shows the situation of our +magnetic pole and line of no variation, the dip of the needle by the +arrows, and the magnetic equator.</p> + +<p>Recent discoveries have shown that the magnetic force is exerted in lines +and currents; that such currents, as physical lines of force, surround +magnets, and currents of electricity. Doubtless such lines of force exist +around the earth and the magnetic poles. There are also <i>longitudinal</i> +lines of force existing and active, between the poles, and extending from +one side of the center to the other, occupying nearly one third of the +magnet. If you take a large needle thoroughly magnetized, place it upon +paper and drop filings of iron upon it, they will become arranged about it +in circular and perpendicular, and also in <i>longitudinal lines</i>, +conforming to the currents.</p> + +<p> </p> +<p class="center"><strong>Fig. 13.</strong></p> +<div class="figcenter"><img src="images/i0107.jpg" alt="" /></div> +<p> </p> + +<p>This experiment is illustrated in all our books on natural philosophy.</p> + +<p>The foregoing diagram, copied from Olmstead’s Philosophy, does not show as +accurately as <ins class="correction" title="original: Faroday's">Faraday’s</ins> projection of the lines upon a globe-magnet<span class="pagenum"><a name="Page_85" id="Page_85">[Pg 85]</a></span> the +comparative distance from the poles of the needle, at which the +longitudinal currents commence and terminate, and <i>where the filings will +not adhere</i> to any considerable extent. The lines shown upon the needle +should bear the same proportion to its length as the trade-winds bear to +that of the earth, measured from pole to pole, and if the needle had a +globular form they would so appear.</p> + +<p>These lines are made by currents arising from one side of the magnetic +equator, and passing over to the other. Doubtless, just such currents +rise, and pass over upon the earth.</p> + +<p>Magnetic and electric currents carry the air with them. This is well +settled by experiment. <i>Oxygen</i>, too, is <i>magnetic</i>, and capable both of +receiving and retaining polarity and of combining with, or attracting and +retaining vapor, and of course the moisture of evaporation. Here then we +have a power existing, capable of producing the result—precisely, and +with evident wisdom adapted to its production—ever present and active; +and no other known agent can.</p> + +<p>Is it not then the agent?</p> + +<p>Let us look a little further. This result is affected by the action of the +sun: the trades with the central belts of rains travel north and south +after it; so does the sun affect the magnetic currents every where, even +the magnetic needle is daily affected by its action, as it increases the +intensity of the terrestrial magnetic currents, and hence its well +established diurnal oscillations.</p> + +<p><span class="pagenum"><a name="Page_86" id="Page_86">[Pg 86]</a></span>Again, along the eastern lines of the continents which skirt the great +oceans on the west, run the northerly and southerly lines of no variation, +and of greatest magnetic intensity. Here are the trade currents gathered +into a volume, which curve and carry unusual fertility to South-eastern +Asia, and North America, and in those great aerial gulf streams we find +the <i>intense</i> electric action which produces the typhoons of the former, +and the hurricanes of the latter. It may still be said that these +conditions and phenomena of the trade-wind region, are not produced by +magnetism or magneto-electricity, <i>but the objector can point to no other +adequate power</i>. That it must be heat, electricity, or magnetism, must be +admitted. There is no other power known. Heat demonstrably can not produce +them. Magnetism or electricity therefore must, and they are doubtless +states or phases of the same power, producing in their different states or +phases the different results. And even heat—atmospheric temperature, is +often, if not always the result of their action. In the present state of +science, it is enough for me that the <i>magnetic longitudinal currents are +there</i>; that they are <i>lines of force</i> and <i>adequate</i>; that <i>oxygen is +magnetic</i>, and therefore the atmosphere must be affected by them—that so +far as we can reason from analogy, they ought to produce the effect upon +the atmosphere which we find produced, and until further light is thrown +upon the subject I shall presume that they do. Every step we take +hereafter in this investigation will confirm the presumption.</p> + +<p><span class="pagenum"><a name="Page_87" id="Page_87">[Pg 87]</a></span>There is one peculiarity to be more particularly noticed before we leave +the trade-wind region, and we are now prepared to notice it.</p> + +<p>The belt of rains, formed by the currents of the two trades, threading +their way through each other—how are they produced? Why should the place +where the currents thus pass through each other be a place of almost daily +precipitation? There is, in fact, no ascension, except that which the +currents have in their line of ascent to attain the elevation which the +magnetic law of the current requires.</p> + +<p>The trades have passed over an evaporating surface and are charged with +moisture. This moisture they hold in magneto-electric combination. +<i>Evaporation</i> does not depend upon <i>temperature</i>. Ice and snow evaporate +at all temperatures (Howard, vol. 1, p. 86). So the cold N. W. wind, full +of positive electricity, will lap up, as it were, the pools from the +earth, with astonishing quickness; and when this electricity is deranging +the action of the machinery and material of the manufacturer, he allays it +by a supply of moisture, with which the electricity can combine. Nor does +the air lose its moisture when below the freezing point. In all parts of +the atmosphere, as at the surface of the earth in winter, moisture is held +in large quantities in the coldest and severest weather; and it is not +till it moderates, and a perceptible <i>electric</i> change takes place, that +it is precipitated as rain or snow. Doubtless there is an exposure of +considerable surfaces, of opposite currents, charged with opposite +polarity, and a constant depolarization where<span class="pagenum"><a name="Page_88" id="Page_88">[Pg 88]</a></span> their surfaces meet. May +there not be a consequent dissolution of the electro-magnetic combination +between the air and moisture, or the excitation of that electric action +which attends or produces like rains every where? and hence the constant +precipitation. This is rendered probable, by the fact that precipitation, +at the meeting of the trades, takes place in level countries in the +day-time, between 10 <span class="smcaplc">A. M.</span> and sunset, in showers, with thunder and +lightning, as with us in summer, although among the mountains the rain +sometimes falls in the night also. The precipitation in the heat of the +day is obviously induced by the action of the sun, although it is by no +means certain that the friction of the opposing surfaces does not assist +in the operation.</p> + +<p>I am well aware that the lines of magnetic force curve upward and carry +the trades with them, and that, therefore, precipitation by condensation +from the mere cold of the upper stratum of the atmosphere is possible. +But, there are three reasons why I do not believe such to be the fact.</p> + +<p>1st. Precipitation takes place in the day time mainly, and in sudden, +isolated, heavy showers and not in steady continuous rain. Nor is there +condensation or continual mist at other hours of the day.</p> + +<p>2d. They occur at a time of day when the sun is affecting the magnetic +currents most powerfully, <i>viz.</i>, between ten o’clock <span class="smcaplc">A. M.</span> and sunset, and +mainly at the time of greatest heat.</p> + +<p>3d. The counter-trades <i>do not precipitate</i> after they leave the rainy +belt, although at a great elevation,<span class="pagenum"><a name="Page_89" id="Page_89">[Pg 89]</a></span> until they reach the outward limits +of the trades; and they <i>do precipitate again</i>, although they gradually +descend <i>nearer the earth</i>, as soon as they become subject to the action +of the currents of an opposite magnetism. Their precipitation is partial +too, even then, and they carry a portion of their moisture through an +atmosphere of the coldest temperature up to the geographical poles.</p> + +<p>A similar result attends the action of the sun in the extra-tropical +regions. Cumuli commence forming in the counter-trade, or at the line +between that and the surface current, at the same time of day that the +diurnal motion of the magnetic needle commences, or the rain clouds form +in the tropics; they continue to enlarge here as there, till about the +same hour of the day that the <i>needle</i> obtains its maximum diurnal +variations; and when the influence of the sun upon the needle ceases, and +it returns to its original status, the cumuli disappear. Hail storms too, +it is said, always, or generally occur in the day time.</p> + +<p>In like manner the sea-breezes and other fair-weather surface winds, rise +in the forenoon with the influence of the sun upon the magnetic currents +and the needle, and die away at nightfall when the influence ceases.</p> + +<p>There are other electro-magnetic, or to speak more correctly, +magneto-electric, effects of the sun’s action equally illustrative, which +tend to show that the precipitation at the passing of the trades, is the +result of their action upon each other, aided by the sun, to<span class="pagenum"><a name="Page_90" id="Page_90">[Pg 90]</a></span> which we +shall allude when we come to speak of the causes and character of the +surface winds of the extra-tropical regions.</p> + +<p>As, however, this takes place only, or mainly, where the threading +surfaces meet, it is but partial, and the body of the respective polarized +currents pursue their way unaffected, toward the opposite magnetic +pole—and there for the present we leave them.</p> + +<p>Storms sometimes originate in these currents, when concentrated, as in the +West Indies, the China Sea, the Bay of Bengal, and Indian Ocean, while +passing through the rainy belt, and move with the current to the +north-west if issuing on the north side of it, and to the south-west if +issuing on the south side of it, until they respectively get beyond the +extreme limits of the trades, and then they curve to the eastward, +imbedded in and following their current. The peculiar extension of the +land to the east on the northern portions of South America, prevents the +gathering of an aerial gulf similar to the one which we have described to +the north-west, entering upon our division of the continent over the Gulf +of Mexico. It is otherwise in the Indian Ocean, and there the storms are +found issuing from the rainy belt on the southern side, sweeping over the +Mauritius and other islands of that ocean, and <i>often simultaneously</i> with +storms issuing on the north over the Bay of Bengal. Colonel Reid mentions +instances and gives a diagram.<small><a name="f2.1" id="f2.1" href="#f2">[2]</a></small></p> + +<p><span class="pagenum"><a name="Page_91" id="Page_91">[Pg 91]</a></span>These storms in milder forms issue from the rain belt at other points, and +may issue any where, but will always be found most extensive and most +violent, that is to say, as hurricanes and typhoons, in the concentrated +volumes of counter-trade on the western side of the great oceans, within a +few hundred miles of the lines of magnetic intensity and no variation, and +when they form in the rainy belt they are highly electric. Most +frequently, however, as we shall see, they form in these currents after +they have issued from the rainy belt, and after they have passed the +extreme limits of the trades and become subject to the circular and +perpendicular magnetic currents which exist north and south of the +longitudinal ones, and which when seen upon the magnetic needle, attract +the filings and cause them to adhere—although but slight attraction or +adhesion takes place where the longitudinal currents exist.</p> + +<p>Such, then, are the atmospheric arrangements and phenomena of the +trade-wind region, and the cause that produces them; such is the character +and cause of the enlarged volume of counter-trade, which spreads out and +blows over our country as permanently as the S. E. trades blow on the +South Atlantic and South America, returning to us the rivers which had run +from us to the sea.</p> + + +<p> </p><p> </p> +<hr style="width: 50%;" /> +<p><span class="pagenum"><a name="Page_92" id="Page_92">[Pg 92]</a></span></p> +<h2><a name="CHAPTER_VI" id="CHAPTER_VI"></a>CHAPTER VI.</h2> + +<p>Coming back now, to a consideration of the course and functions of the +counter-trade after it leaves the northern limit of the surface-trades, we +find it curves to the eastward and gradually assumes about an E. N. E. +course, and becomes a W. S. W. current where it crosses the line of no +variation, and continues on until it passes off over the Atlantic; and +this course and curve is analogous to what may be found true of the +counter-trades every where. It is best illustrated by the course of all +the storms (in the American sense of the word, as distinguished from +thunder showers and other brief rains), which have been traced north or +south of the limits of the trades. It was found by Mr. Redfield in most of +the storms investigated by him, which originated within, or north of the +tropics.</p> + +<p>Doubtless it was the actual course of the others, and that the +investigation was imperfect. All the great autumnal, winter, or spring +storms which have traversed the whole or any considerable portion of the +territory of the United States, east of New Mexico, which have been +investigated by Professors Espy, Loomis, Redfield, or others, have been +found to follow this course. A storm which passed over<span class="pagenum"><a name="Page_93" id="Page_93">[Pg 93]</a></span> Madeira, appears +from the investigations of Colonel Reid to have followed the same law of +curvature.</p> + +<p>And so, doubtless, did another which he has described as passing over the +Levant. The storms which supply the winter rains of California and Utah, +reach them by this law of curvature and progress, after the northern +limits of the trades have descended to the south with the sun, so that the +counter-trades of the Pacific may descend to the surface and curve in upon +them. But the absence of a concentration of the counter-trade, and its +deficient action because of its passage over mountain ranges, and their +location so near the northern limit of the trades that their storms can +not expand and become extensive, as well as their weaker magnetic +intensity, prevent their storms from becoming violent, and their supply of +rain is not large and much of it falls in showers. The same is true of the +Barbary States, of Syria, and Persia, and of Southern Europe; and indeed +of all the countries of the globe which lie between the winter and summer +extreme limits of the surface-trades, and without the limits of the two +concentrated counter-trades. Enough appears in the writings of the +meteorologists of Europe to show, that their long continued rains, which +are analogous to our storms and are <i>preceded by the formation of the true +cirrus of the counter-trade</i>, follow the same great law of curvature and +progress; although the presence of the Gulf Stream with its mass of south +polar waters on the western side of the British Islands, Denmark, and +Norway supplies them with showers,<span class="pagenum"><a name="Page_94" id="Page_94">[Pg 94]</a></span> and fogs, and cumuli from the west and +north-west, and makes the mean of the surface winds of their storms +somewhat variant from ours. A like law reversed prevails in the southern +hemisphere. The storms of New Holland and the Indian Ocean, south of the +limits of the trade, curve to the eastward and travel about south-east, +their <i>south-west</i> being a <i>clearing off wind</i> as our <i>north-west</i> is, and +<i>precisely similar in all its other characteristics</i>, where the relation +of magnetic intensity is the same.</p> + +<p>The storms of the Pacific on the S. W. coast of South America, in like +manner travel to the S. E., flooding the western slopes of the mountain +ranges with rain, and aggravated by the intensity of the magnetic currents +at the extremity of the continent in a high latitude, meet the mariner in +the face as he emerges from under the lee of the land and attempts to pass +the Horn. It will ultimately be shown that the precipitation which takes +place, as the storms and counter-trades pass north and east in the +northern hemisphere and south and east in the southern hemisphere, is +owing less to cold than increased magnetic intensity. And all this is the +result of one great uniform law, existing every where, varying in its +phenomena only in consequence of the difference in volume, and +magneto-electric intensity of the portions of the counter-trade, as of the +surface-trade at different places, and the different magnetic intensity of +the local perpendicular and circular currents of the earth over which they +pass, at different periods and at different points.</p> + +<p><span class="pagenum"><a name="Page_95" id="Page_95">[Pg 95]</a></span>Mr. Redfield and Lieutenant Maury have assumed that our S. W. current +comes from the Pacific Ocean. Aside from the adverse evidence which the +investigations of the former in relation to the course of the West Indian +storms, and their curving over the continent, furnish to the contrary, and +that which has herein before been stated in relation to the law of +curvature, it is obvious they are mistaken, for another and conclusive +reason.</p> + +<p>In order to reach us from the Pacific in a direction from S. W. to N. E., +it must pass the table lands and mountain ranges of Mexico and New Mexico, +and it would supply them bountifully, even if it did not thereby leave us +comparatively rainless and sterile. Every where currents passing from the +ocean <i>over mountain ranges</i> part with a large share of their moisture. +Thus the counter-trade which curves over the Andes and over Peru, is +deprived of its moisture and leaves the western coast rainless. So in +degree of the counter-trade which curves over the Himalaya and Kuenlon +Mountains, and from there passes over the Desert of Cobi, to the north and +east—it is deprived by those elevated ranges of its moisture. So the +mountains on the south-western coast of South America are drenched with +rain, while Patagonia, which lies on the east of them is comparatively +dry. And so of every other country similarly situated.</p> + +<p>Now the mountain ranges and table lands of Mexico are not thus supplied +with moisture. For the space of four months in Southern and less in +Northern<span class="pagenum"><a name="Page_96" id="Page_96">[Pg 96]</a></span> Mexico, and in summer, and while the belt of the tropics is +extended up over them, they have rain and in daily showers which <i>travel +up from the south</i>, indicating the course of the counter-trade. (See +Bartlett’s Personal Narrative, vol. ii. p. 286.) At other seasons, and +while we are bountifully supplied, they are dry. In short, there are no +two portions of the earth that differ more widely in regard to their +supply of moisture, and all their climatic characteristics and relations. +It is therefore, according to all analogy, impossible that our +counter-trade should come from the South Pacific across the continent and +below 35°, and in this also those <ins class="correction" title="original: gentleman">gentlemen</ins> are mistaken.</p> + +<p>Messrs. Espy and Redfield recognizing the existence of “a prevailing” S. +W. current, but considering the surface-winds beneath it as the principal +actors in producing the atmospherical conditions and changes, have +attributed no office to that current, except that of giving direction and +progression to our storms. This is their great mistake. It plays no such +unimportant part in the philosophy of the weather, as we have already +incidentally seen, and will proceed still further to consider.</p> + +<p><i>All our storms originate in it.</i> This we may know from analogy.</p> + +<p><i>Where there is no counter-trade, outside of the equatorial belt of rains, +and within influential distance of the earth, there are neither storms nor +rain.</i> So, when, as we have seen, the concentration of the volume of +northern counter-trade in the West Indies, gathered<span class="pagenum"><a name="Page_97" id="Page_97">[Pg 97]</a></span> by the hauling of the +S. E. trades more from the east, as they approach the central belt, +diminishing the volume of the counter-trade over the North Atlantic, the +calms and drought of the horse-latitudes are found. And when the +counter-trade is small in volume and weak in intensity, by reason of the +fact that the surface-trades from the opposite hemisphere which constitute +it, formed upon land where evaporation was small, as upon Southern Africa +and New Holland, or formed where the magnetic intensity was weak, or +passed over mountain ranges in their course, the annual supply of rain, +the ranges of the barometer, and the alternations of atmospheres +conditions are remarkably less.</p> + +<p>We have already seen where the rainless portions of the earth are, and why +they are so; because those lying north of the northern limit of the +equatorial rainy belt were yet too far south to be covered by the line of +extra-tropical rains; or in other words, too far south to be uncovered by +the surface N. E. trades and the longitudinal magnetic currents, and to be +covered by the counter-trades in contact, or nearly so with the earth, and +influenced by the perpendicular north polar magnetic currents. Thus we +have seen that the rains of Southern Mexico were summer rains, due to the +northern extension of the equatorial rainy belt; those of California were +winter rains, due to the southern extension of the extra-tropical rains +following the N. E. surface trades. We have also briefly alluded to the +fact that either side of the equatorial rainy belt, evaporation is going +on for<span class="pagenum"><a name="Page_98" id="Page_98">[Pg 98]</a></span> months under a vertical sun, without precipitation—unless it be +from an occasional brief storm of great intensity which originates in that +belt at the line of it, and passing on in the counter-trade, reverses, for +the time being, by its concentrated and powerful action, like a magnetic +body introduced into the field of another magnet, the surface-trades. Mere +evaporation then, does not produce the storm, or shower, or rain, where +most active in the dry torrid zone. It may be said that those dry portions +are, for the time being (as the rainless portions of the earth are +continually), within the operation of the surface-trades, and that +therefore the evaporated moisture is carried away by them toward the +equatorial rainy belt. Precisely so; but why carried away? Why should it +not condense, occasionally, at least, and drop the rain as it passes +along, if a great supply of moisture from excessive evaporation could +furnish rain. Perhaps it may still be said it is going from a cold to a +warm section. This is not true, as we have shown.</p> + +<p>But, it may be said that the rainless regions at any rate receive no +moisture, and therefore can not supply any by evaporation. This would not +meet the case, as it would still be true that when the rainy belt has left +a given spot, the dry weather sets in with excessive evaporation, and the +north-east trades in summer, blowing from the countries lying north of the +rainless regions, and which have been supplied during the interval by the +extra-tropical rains, and are loaded with evaporation, are passing over +the rainless regions on their<span class="pagenum"><a name="Page_99" id="Page_99">[Pg 99]</a></span> way to enter the central belt. So blow the +N. E. trades from the Mediterranean, and the Barbary States <i>over the +Desert of Sahara</i> and into the rainy belt south of it; but drop no +moisture on their way, because exposed to no magnetic currents of an +opposite polarity.</p> + +<p>But it is not true that all the rainless regions are without evaporation. +Egypt is an exception. The annual freshets of the Nile saturate its +central valley, and vast reservoirs of water are saved from it and let out +over its surface, and it all evaporates, but produces no rain. And so are +large quantities turned aside and scattered over the bottom lands of +Northern Mexico, and other countries, during the dry season, and their +evaporation furnishes no rain. Hygrometers and dew points are of no +consequence there—nor are they of any, on either side of the rainy belt, +where six perpendicular feet of moisture is evaporated in six months.</p> + +<p>Again we have alluded to a strip of coast on the Pacific west of the +mountain ranges of South America, lying partly in Peru, partly in Bolivia, +and partly in Northern Chili, which, although long and narrow, washed by +the broad Pacific Ocean, is without rain. South America has no other +<i>wholly</i> rainless region, so far as is known. A part of this region would +lie between the equatorial belt of rain, and the southern extra-tropical +one, and never be covered by either; but the volume of N. E. trades from +the Atlantic, although from the make of the land not concentrated to so +great an extent as the volume of<span class="pagenum"><a name="Page_100" id="Page_100">[Pg 100]</a></span> S. E. trade on the north, and therefore +not so liable to hurricanes and other violent storms, is yet sufficiently +so to carry the southern line of the equinoctial rainy belt down in winter +to the summer line of extra-tropical rains, and give a supply of rain to +all the continent—leaving no strictly rainless region south of the +equatorial rainy belt and east of the Andes. Those mountains, however, +present a barrier to its south-western progress which it doubtless passes +to some extent, but deprived of its moisture, and unable to supply the +rainless coast region of Peru, Bolivia, and Northern Chili. There is, +therefore, a portion of this rainless line of coast which is within the +region of extra-tropical rains, over which a portion of the N. E. trades +of the Atlantic, as a counter-trade, should or do, curve, and where there +should therefore be extra-tropical rains. It is washed by the Pacific, an +evaporating surface, and westerly and south-west breezes are drawn in from +that ocean over it. Why then is it rainless? The only reason which can be +assigned why rain does not fall there is that the high mountain ranges of +the Andes intercept and perhaps in part divert the counter-trade, and +deprive that portion of it which passes them, of its moisture, by that +reciprocal action of opposite polarities which takes place whenever and +wherever the trade approaches so near the earth; and it curves over the +narrow line of coast with the feeble condensation, and imperfect forms, +and varied coloring which mark so peculiarly the rainless clouds of that<span class="pagenum"><a name="Page_101" id="Page_101">[Pg 101]</a></span> +region. (See Stewart’s Journal of a Voyage to the Sandwich Islands, page +72.)</p> + +<p>Again, it is estimated, and on reliable data, that twelve perpendicular +feet of water are annually evaporated from the surface of the Red Sea, +between Nubia on one side, and Arabia on the other; yet they are both +rainless countries, except so far as the inter-tropical belt of rains +extends up on to a small portion of them. The moisture of evaporation, +floated up from a surface covered by the surface-trade is invariably so +combined as to remain uncondensed till it has passed south into the +equatorial rainy belt, and over to the opposite hemisphere, and been +exposed to the currents of an opposite magnetism.</p> + +<p>Again, the N. E. trades extended up in summer over the Mediterranean Sea, +an evaporating surface, blow over the Barbary States in June and July, but +furnish no rain. And so of the S. E. or N. E. trades which blow over +Brazil and other countries in the absence north or south of the tropical +belt of rains.</p> + +<p>It is obvious from these facts—and more like them might be cited—that +mere evaporation, however copious or long continued, does not make the +storm or shower in the locality where it takes place, and <i>without the +existence and influential agency</i> of a counter-trade; and that <i>reciprocal +action</i>, whatever it may be, that takes place <i>between it and the earth</i>.</p> + +<p>Again, our own experience is conclusive of this. We have no surface-trade +north of 30°, and yet a long drought and great evaporation may follow a +wet spring. Belts of droughts and frequent rains<span class="pagenum"><a name="Page_102" id="Page_102">[Pg 102]</a></span> occur every year in +different portions of the country side by side, and <i>the dividing line +follows the course of the counter-trade</i>, and is sometimes distinctly +marked for weeks. When a change occurs in the counter-trade, whether from +causes existing there or the influence of terrestrial magnetism (in +relation to which we shall inquire hereafter), showers form or storms come +on: until it does they will not. Efforts at condensation will occasionally +appear, but they will be feeble and ineffectual, and occasion a repetition +of the axiom that “all signs fail in a drought.” And we may know it from +direct observation.</p> + +<p>The first indications of a storm, and of most if not all showers, are +observable in the counter-trade. These indications, so far as they are +visible, are of course to be looked for in the west; although the +direction and character of the surface-winds are often indicative of these +changes when not visible at the west as we shall see.</p> + +<p>The indications are those of condensation, and vary very much in different +seasons of the year. It is not my purpose in this place to examine them +particularly. They will be alluded to hereafter under the head of +prognostics. Suffice it now to say, then, that whether it be the long +threads or lines of cirrus which occur in the trade in the winter after a +period of severe cold, following the interposition of a large volume of N. +W. cold air and the elevation of the counter-trade; or the forms of cirrus +which occur at other times and other seasons; or whether it be the +ordinary bank at night-fall, or the evening condensation<span class="pagenum"><a name="Page_103" id="Page_103">[Pg 103]</a></span> which makes the +“circle” around the moon, or the morning cirro-stratus haze which +gradually thickens, passes over and obscures the sun, all which may be +followed by the easterly scud and winds: they are alike condensation in +the trade, the advance or forming condensation of a storm or showers.</p> + +<p>The state of the weather, whether hot or cold, is extensively affected by +this trade current. As we have already suggested, the mere presence of the +sun in its summer solstice, or its absence in winter, is not an adequate +cause of all the sudden and various changes to which we are subject. The +state of the counter-trade, which is always over, or <i>within influential +distance of us</i>, and sometimes probably in contact with us—the nature of +the surface-winds which it is at any given time creating and attracting +around us, and the electric condition of the surface-atmosphere <i>induced</i> +by it, or by the immediate action of the earth’s magnetism, produce those +sudden changes which mark our climate. When no intervening surface-winds +elevate it above us, and there is no storm or other condensation within +influential distance, it induces the gentle balmy S. W. wind of +spring—the cooling S. W. wind of summer—the peculiar Indian summer air +of autumn, or the comparatively moderate, although cold, open weather of +winter. If there be a partial tendency to condensation in it, the cumuli +form under the magnetic influence excited by the sunbeams from ten to +three o’clock in the day, and float gently away to the eastward, +disappearing before night-fall. If the disposition to condensation<span class="pagenum"><a name="Page_104" id="Page_104">[Pg 104]</a></span> is +stronger, whether inherent or induced by an increased local activity of +terrestrial magnetism, these cumuli will increase toward night-fall, or +earlier, and terminate me showers; and if it is in a highly electrical +state, the still oppressive sultriness which precedes the tornado, and +that devastating scourge may appear. If this disposition to condensation +becomes extensive, cirri form and run into cirro-stratus, or they extend, +coalesce, and form stratus; the surface-wind will be attracted under them, +the thermometer fall in summer or rise in winter, and a storm begin. +Intense action and sudden cold may exist in and under this counter-trade +over the southern portion of the country, while all is calm, warm, and +balmy at the north. Heavy snow storms sometimes pass at the south when +there are none at the north, and a corresponding state of the weather +follows. If a large body of snow fall at the north, the winter is cold, +regular, and “old fashioned;” if little snow falls at the north and more +at the south, the winter at the north is open and broken. I have known the +ice make several inches thick at Baltimore and Washington, when none could +be obtained for the ice-houses on the Connecticut shore of Long Island +Sound. In short, although heat and cold are mainly dependent upon the +altitude of the sun, aided by the other arrangements we have alluded to, +yet the counter-trade, and the reciprocal action which takes place between +it and the earth, are most powerful agents, mitigating the rigors of +winter, bringing about the changes from cold to warm weather which<span class="pagenum"><a name="Page_105" id="Page_105">[Pg 105]</a></span> the +sun is <ins class="correction" title="original: two">too</ins> far south to produce. And on the other hand, by this reciprocal +action, producing the electrical phenomena, the gusts, the tornadoes, the +hail storms, and the cool seasons of summer, and the period of intense +cold in winter.</p> + +<p><i>All our surface-winds, except the light, peculiar W. S. W. wind which is +felt where the counter-trade is in contact with the earth, and which is a +part of it, and perhaps the genuine N. W. wind which is very peculiar, are +incidents of the trade, and are due to its conditions and attractions.</i> We +have already said this was true of the easterly wind and scud of a +storm—it is alike true of all. The storm winds east of the Alleghanies +are usually, though not always, from the eastward. They are sometimes from +the southward, as they doubtless are still more frequently in the interior +of the continent.</p> + +<p>There is occasionally a southerly afternoon wind, followed by short rains +in spring and fall, or a succession of showers in summer, which is rather +a precedent wind than a storm wind; blowing toward and under an advance +portion of the storm at the north, and hauling to the eastward when the +rain sets in, or to the westward when the showers reach us.</p> + +<p>When there are no storms, or showers, or inducing electric action in the +counter-trade, within influential distance to disturb the surface +atmosphere, it is calm. If a storm approaches, or forms within inducing +distance, the surface atmosphere is <i>affected</i> and <i>attracted toward the +storm</i>, from one or more points, and “blows,” as we say, toward and under +it. It <span class="pagenum"><a name="Page_106" id="Page_106">[Pg 106]</a></span>commences blowing first nearest the storm, and extends as the +storm travels, or becomes more intense and extends its inducing influence. +I have repeatedly noticed this in traveling on steamboats and railroads +running <i>toward</i> or <i>from</i>, and in several instances <i>through</i> a storm, +and telegraphic notices and other investigations prove it. The point from +which the surface atmosphere is attracted and blows, depends very much +upon the position of the storm in relation to bodies of water and the +point of observation, and its shape; and the force with which it may blow +will depend much upon its intensity.</p> + +<p>Let us take an instance or two by way of illustration of all these points; +and as I have given instances of summer in the introduction, we will take +those of winter. It is January of an “old fashioned winter;” the snow is +about three feet deep in Canada, about one foot in Southern New York, and +a few inches in Philadelphia, and so extends west to the Alleghanies at +least. For several days the sky has been clear, the thermometer rising in +the day-time, in the vicinity of New York to about 25° Fahrenheit, falling +at night to about 6°, with light airs from the N. W. during the middle and +latter part of the day; the counter-trade and the barometer both running +high; cold but pleasant, steady, winter weather. There is a warm +south-east rain and thaw coming, as one or more such almost invariably +occur in January. How coming? The sun is far south, and shines aslant, but +through a pure and windless atmosphere; he has tried for several days to +melt the snow from<span class="pagenum"><a name="Page_107" id="Page_107">[Pg 107]</a></span> the roof; a few icicles are pendant from the eaves; +but the body of the snow is still there. How can a thaw come? not from the +sun, surely. No, indeed, not from the action of the sun directly, upon our +country, nor from the Atlantic or the Gulf Stream which is off our coast. +But a portion of the current of counter-trade is coming, heated by his +rays and the warm water in the South Atlantic, in an intense +magneto-electric state, capable of inducing an electro-thermal change in +the surface atmosphere which it approaches, and of being reciprocally +acted upon by the north polar terrestrial magnetism. It is now over +Northern Texas and Western Louisiana, it will be here day after tomorrow. +The day passes as the day previous had passed; the sleigh-bells jingle +merrily in the evening; the moon shines clear all night; the storm is +coming steadily on, but its influence has not reached us, and the morning +and midday are like those which preceded it. As nightfall approaches, +however, the thermometer does not fall as rapidly as on the day previous; +the sun shines dimly and through lines of whitish cirrus cloud extending +from the horizon at the west, appearing darker as the sun descends and +shines more <i>horizontally</i> through them—perhaps mainly in the N. W.—and +which extend up and over toward the E. N. E. The air next the earth begins +to feel raw; it is changing, not from warm to cold, but <i>electrically</i> +from positive to negative; and dampening, from a tendency to condensation +by induction, as we shall see—the same condensation which in warm +weather<span class="pagenum"><a name="Page_108" id="Page_108">[Pg 108]</a></span> may be seen on flagging stones, and walls, and vessels containing +cold water. The advance cirrus condensation of the storm is over us and +affecting us; the earth too is affecting the adjacent atmosphere by action +extended from beneath the storm. Still there is no wind, although sounds +seem to be heard a little more distinctly from the east, and so ends the +day. Evening comes, and the moon wades in a smooth bank of cirro-stratus +haze, with a very large circle around her; the cirrus bands of haze have +coalesced and formed a thin stratus. The storm is coming steadily on, its +condensation is seen to be thicker as it approaches, it is now raining +from one hundred to one hundred and fifty miles to the west, but we do not +know it.</p> + +<p>That it is about to storm all believe, for all are conscious of a change. +The candle if extinguished will not relight as readily, if at all, on +being blown; there is a crackling almost too faint for snow in the fire; +the sun did not set clear; the old rheumatic joints complain, and the +venerable corns ache.</p> + +<p>Morning comes, and the storm is on. The wind is blowing from the S. E., +the scud are running rapidly from the same quarter to the N. W., the +thermometer continues rising, and it rains. The storm has reached us and +the thaw has commenced. Gradually, as the densest portion of the storm +cloud reaches us, it darkens; the scud are nearer the earth, and run with +more rapidity; the rain falls more heavily and continuously, and by the +middle of the day a thick fog has enveloped the earth; the wind is<span class="pagenum"><a name="Page_109" id="Page_109">[Pg 109]</a></span> dying +away, and the trade itself, with its southern tendency to fog, has settled +near us; the barometer has fallen, the thermometer is up to fifty degrees, +the water is running down the hills, the snow is saturated with water and +is disappearing under the influence of the fog, the rain, and the warm +air. Evening comes; the south-east wind and the rain have ceased; the rain +clouds have passed off to the eastward; the fog has followed on and +disappeared; there is a light trade air from the S. W.; the moon shines +out, and a few patches of stratus, broken up into fragments and melting +away, are following on in the trade: the storm is past.</p> + +<p>Hark! to the tones of Boreas as he bursts forth from the N. W., and +rushing, whistling, howling, dashes on between the trade and the earth, +following the storm. Now the barometer rises rapidly, the thermometer +falls, and in an incredibly short time all is congealed, and cold and +wintery as before. The cold N. W. wind has again interposed between the +trade and the earth; the trade is elevated a mile or more above it and is +entirely free from its influence and from condensation; the deep blue of a +sky “as pure as the spirit that made it” is over us, and steady winter +reigns again.</p> + +<p>It is obvious that there was nothing in the action of the sun upon our +snow-clad country, to induce the thaw or the storm. It began, continued, +approached, and passed off to the N. E. in the counter-trade. The S. E. +wind which existed every where within its influence: in the interior +States, Missouri,<span class="pagenum"><a name="Page_110" id="Page_110">[Pg 110]</a></span> Illinois, Indiana, Ohio, Michigan, and in Canada, as +well as upon the Atlantic coast, commencing in the former earlier than +upon the last, was the result of its induction and attraction. Of the N. +W. wind that followed we shall speak hereafter. If any one doubts whether +this be a true sketch let him examine the investigation of a storm +published by Professor Loomis, or observe for himself hereafter. If, +however, the storm of Professor Loomis is referred to, it should be +remembered that his notes show the occurrence of a slight distinct snow +storm at the N. W. stations one day in advance of the principal storm. The +latter appears first as rain at Fort Towson, on the nineteenth, moving +north and curving to the east—its center passing near St. Louis, and +south of Quebec, and the whole storm enlarging as it advanced.</p> + +<p>Take another instance. Since the thaw it has not been quite as cold as +before; but the rain-soaked snow is hard and solid, the ground, where the +snow was blown or worn off, icy and slippery—the thermometer falls during +the night to about 12°, and rises to about 30°; the sun makes no +impression upon the snow; the firmament is of the deepest blue, the +borealis at night vivid. “O, for a storm of some kind, to mitigate the +still severe cold;” for the thaw has made us more sensitive, and storm +winds do blow warm in their season. But patience, it will come. Another +day, or two, perhaps, pass: the sun rises as usual, the thermometer has +the same range still. “Long cold snap,” we exclaim; “how long will it +last?”</p> + +<p><span class="pagenum"><a name="Page_111" id="Page_111">[Pg 111]</a></span>A change is coming, but this time it will snow. About an hour or two after +<ins class="correction" title="original: surise">sunrise</ins> the cirrus threads are discoverable again in the west, but now +they are most numerous in the S. W. As the day passes on they thicken and +advance toward the E. N. E., the sun begins to be obscured, the +thermometer rises, and it slowly “<i>moderates</i>.” There is a snow storm +approaching from the S. W.</p> + +<p>But the thermometer rises slowly; it must get up to 26° or 28° before it +can snow much. I have known in one instance, at Norwalk, a considerable +fall of snow, although much mingled with hail, when the thermometer stood +at 13° above zero, and one, a moderate fall, some two inches, with it at +24°, but these were exceptions. The snow range of the thermometer on the +parallel of 41° north latitude, and south of it, is from 26° to 30° above +0°; when colder or warmer it may snow to whiten the ground, or perhaps +barely cover it, but usually rains or hails. We have seen that in the +polar regions, according to Dr. Kane, it is about zero, but the rise of +the thermometer there, previous to the snow, was about the same as here, +<i>i. e.</i>, from 15° to 25°. This fact is instructive. Since the foregoing +was written, and on the 7th of February, 1855, a snow-storm of +considerable length set in, with the thermometer at 5°, and continued more +than twenty-four hours, the thermometer gradually rising. The snow was +very fine, like that described by Arctic voyagers as falling in extreme +cold weather.</p> + +<p>As the dense and darker portions of the storm <span class="pagenum"><a name="Page_112" id="Page_112">[Pg 112]</a></span>approach, and although the +sun is obscured, and the ground frozen, it continues to moderate, and at +evening, when the thermometer is up to 28°, and the dense portion of the +storm has reached us, gently and in calmness the snow begins to fall. +Perhaps a light air following the storm, or the presence of the trade near +the earth, at first inclines the snow-flakes to the eastward. This is +frequently so at the commencement of snow storms. Ere long, however, the +wind rises from the N. E., and the snow is driven against the windows, +rounded and hardened by the attrition of its flakes upon each other, in +their descent through the eddying and opposite currents. The next day we +rise to witness a heavy fall of snow, perhaps, and a continued driving N. +E. storm, in full blast; the snow whirling and settling in drifts under +the lee of every fence or building.</p> + +<p>Can it be, you ask, that this driving wind is but an <i>incident</i> of the +storm? the result of <i>attraction</i>, while the storm clouds are sailing +quietly and undisturbed on in the counter-trade above, directly over the +gale which is blowing below? It is even so. Nor has it “backed up,” as it +is termed by those who have ascertained that it has commenced snowing +first, and cleared off first, at a point west of them. You saw, or might +have seen, the cirro-stratus cloud passing to the E. N. E. in the +afternoon, and until the snow-flakes filled the air, and the clouds became +invisible. You may still see that the wind will die away before the storm +breaks, and “come out” gently from the S. W., unless it should back into +the northward and<span class="pagenum"><a name="Page_113" id="Page_113">[Pg 113]</a></span> westward, and in either event you may see the last of +the storm clouds, as you did see, or might have seen the first of them, +pass to the eastward. Toward night the wind dies away, and the storm +passes off abruptly, or the sky becomes clear in the N. W. Now you may see +the smooth stratus storm cloud, continuous, or breaking up into fragments +and passing off to the east, even at the edge which borders the clear sky +in the west or north-west, to be followed that evening or the next day, by +the north-west wind and its peculiar fair-weather scud.</p> + +<p>I have given these as instances illustrating the manner in which rain and +snow storms originate the surface easterly winds in winter.</p> + +<p>But it must not be supposed that they commence with precisely the same +appearances in every case in winter; much less in summer. There is very +great diversity in this respect, in different seasons, and in different +storms during the same season. A great many different and accurate +descriptions might be given, if time and space would permit, which all +would recognize as truthful. Very frequently in summer, and sometimes in +winter, the wind will set in from the eastward, and blow fresh toward a +storm, before the condensation in the trade, which forms the eastern and +approaching edge of the storm, has assumed the form of a distinct cloud. +Not unfrequently, when it is calm next the surface, a narrow stratum of +easterly wind, a half a mile or a mile above the earth, may be seen with a +continuous fog, condensing, but not in considerable patches like the<span class="pagenum"><a name="Page_114" id="Page_114">[Pg 114]</a></span> +usual scud, running with great rapidity toward the storm. Such a stream of +fog blew with great rapidity for thirty-six hours toward the storm which +inundated Virginia and Pennsylvania, in 1852, and carried away the Potomac +bridge at Washington. Such a stream of fog was visible the evening before +the great flood of 1854, which inundated Connecticut, and curried away so +many railroad and other bridges. I have also seen such a stream of fog +running at about the same height, when it was calm at the surface, from +the S. W. toward a violent storm which formed over central New +England—and from the north toward a heavy storm passing south of us. Such +strata form, as far as I have been able to discover, the <i>middle current</i> +of storms which are accompanied with very heavy falls of rain. These +double currents are much more common than is supposed. East of the +Alleghanies, short and heavy rain storms, which commence north-east, +hauling to the south and lighting up about mid-day <i>after a very rainy +forenoon</i>, frequently have a S. E. or S. S. E. middle current of this +character, which involves the whole surface atmosphere when the storm has +nearly passed, and the N. E. wind dies away, and the wind seems to haul to +the S. S. E. and S.; so that it is rather the prevalence of a <i>different</i> +and <i>coexisting current</i>, than a hauling of the <i>same wind</i>, which marks +the period of lighting up in the south.</p> + +<p>Sometimes the easterly wind will set in and blow a day or two before the +border of the storm reaches us. Sometimes the storm is passing, or will +pass, in<span class="pagenum"><a name="Page_115" id="Page_115">[Pg 115]</a></span> its lateral southern extension, south of us, and the +condensation in the trade extends over us sufficiently dense to induce an +easterly current beneath it, but not dense enough to drop rain, and then +we have a dry north-easter. I can not, within the limits I have +prescribed, allude to all the peculiarities attending the induction and +attraction of an easterly wind, by the storm in the counter-trade. They +are readily noticeable by the attentive and discriminating observer, and +their existence and cause is all with which I have to do at present.</p> + +<p>Winds from the north, or any point from N. N. E. to N. N. W., are +comparatively infrequent in the United States, east of the +Alleghanies—though it is otherwise in the vicinity of the great lakes.</p> + +<p>Sometimes the wind “backs,” as sailors term it, during a N. E. storm, from +the N. E. through the N. N. E., N., and N. N. W. to N. W. When this takes +place, it is toward the close of the storm. Occasionally, though very +rarely, it continues to storm after the wind has passed the point of N. N. +E., and until it gets N. W. I have known a few instances in the course of +thirty years, and but a few. They are exceptions—rare exceptions. When +the wind thus backs from the N. E. to the N. W. through the N., you may be +very certain that the body of the storm, or at least the point of greatest +intensity and greatest attraction, is at the time passing to the southward +of you. This is most commonly the course of the wind when the storm +extends far south and lasts several days, and does not extend north far, +or if so, with<span class="pagenum"><a name="Page_116" id="Page_116">[Pg 116]</a></span> much intensity, beyond the point of observation. The +change of the wind is explained by the situation of the focus of intensity +and attraction, to the south of the observer, and its passage by on that +side.</p> + +<p>Probably in locations further north and (as I think I have observed) south +of the lakes, it may be more frequent than upon the parallel of 44° east +of the Alleghanies (which is as far north as I have observed), inasmuch as +the further north the locality, the more likely storms and other +disturbances in the counter-trade will be to pass to the southward of it.</p> + +<p>Between the N. E. and S. E. the wind may blow from any point, before and +during storms, and in a clear day in the morning, as a light variable +breeze, or, after mid-day, toward approaching showers. I have known it +blow all day during a storm from due east; to change back and forth +between south-east and north-east, and to blow for hours from any +intermediate point—as different portions of the storm were of different +intensity, and exerted a more or less powerful inducing influence; and +doubtless this often takes place at sea. It depends upon the situation of +the focus of attraction of the storm, its shape relative to the particular +locality, and with reference to the atmosphere east of it, and peculiar +local magnetic action; or, as is sometimes the case in low latitudes, is +owing to the fact that the storm is made up of many imperfectly connected +showers, which have different force, and induce changeable and baffling +winds.</p> + +<p>The inducing and attracting influence of the <span class="pagenum"><a name="Page_117" id="Page_117">[Pg 117]</a></span>approaching storm is exerted +sooner, and with most force, upon the surface atmosphere, over bodies of +water like the ocean and the lakes. Thus, the wind will set from the +eastward toward an approaching storm out upon Long Island Sound, for hours +before it is felt upon either shore; and when all is calm in the evening +on land, and often before the moon forms a halo or circle in the milky +condensation of the approaching storm, or any sign of condensation is +visible, the breaking of the waves upon the shores may be heard. Doubtless +this may be observed on the shores of the Atlantic at other points.</p> + +<p>This power of attracting the surface atmosphere from bodies of water like +the ocean and the great lakes, will account for two apparent anomalies, +mentioned by Mr. Blodget in a valuable and instructive article read to the +Scientific Convention, in 1853, regarding the annual fall of rain over the +United States.</p> + +<p>First—the influence of mountains in extracting the water from the +atmospheric currents which pass over them, is well known and readily +explainable. Mr. Blodget, however, found that the source of our rains, +whatever it might be, when it reached the Alleghanies, was so far +exhausted of its moisture that those mountains extracted less from it than +fell to the westward, by some five to ten inches annually; and that the +fall of rain upon them was less than upon the Atlantic slope eastward of +them, to the ocean. This does not accord with observation elsewhere, but +is easily explained. As the storm approaches the ocean, it attracts in +under it the surface atmosphere<span class="pagenum"><a name="Page_118" id="Page_118">[Pg 118]</a></span> of the ocean, loaded with vapor, +condensing in the form of fog and scud, as it becomes subject to the +increasing influence of the storm. Although the scud and fog would not of +itself make rain, it aids materially in increasing the quantity of that +which falls through it. The drops, by attraction and contact, enlarge +themselves as they pass through, in the same manner as a drop of water +will do in running down a pane of glass which is covered with moisture. +The small drop which starts from the upper portion of a fifteen-inch pane, +will sometimes more than double its size before it reaches the bottom. <i>It +is by this power of attracting the surface atmosphere, which contains the +moisture of evaporation, under it, and inducing condensation in it, that +the moisture of evaporation which rarely rises very far in the atmosphere +is made to fall again during storms and showers.</i> This attraction of a +moist atmosphere from the ocean accounts for the excess of rain on the +east of the Alleghanies, compared with its fall upon them. So the great +valley of the Mississippi is comparatively level, and less of its water +runs off than of that which falls upon the Alleghanies. There is, +therefore, more moisture of evaporation in the atmosphere of the former to +be thus precipitated and add to the annual supply of rain upon that +valley, and it exceeds that which falls upon the Alleghanies. Those +mountains, too, are elevated but about 1,500 feet above the table-lands at +their base, and exert little influence on the counter-trade. If they, were +6,000 or 8,000 feet high, a different state of things would exist.</p> + +<p><span class="pagenum"><a name="Page_119" id="Page_119">[Pg 119]</a></span>Second—Mr. Blodget found the quantity of rain which fell in Iowa, and to +the south and west of the lake region, to be greater than fell over the +lake region itself. This is doubtless in part owing to the same cause. The +counter-trade, in a stormy state, attracts the surface atmosphere from the +lake region, with its evaporated moisture, before it arrives over it, and +therefore more rain falls S. W. of the lake region than upon it. This +power of attracting the surface wind of the ocean in under it, produces +the heavy gales which affect our coast, and which are rarely felt west of +the Alleghanies to any considerable degree; and a storm coming from the W. +S. W., extending a thousand miles or more from S. S. E. to N. N. W., may +have the wind set in violently at S. E. on the <i>southern coast first</i>, and +at later periods, successively, at points further north, and thus induce +the belief that the storm traveled from south to north.</p> + +<p>Mr. Redfield finding that some of the gales which he investigated, +particularly that of September 3d, 1821, did not extend far inland, and +commenced at later periods regularly, at more northern points, concluded +that the gale traveled along the line of the coast to the northward. In +this, and in relation to the storm of 1821 (and perhaps some others), he +has been deceived. My recollections of that storm are accurate and +distinct. But I shall recur to this again when I come to speak of his +theory.</p> + +<p>Toward storms, or belts of showers which would be storms if it were not +summer and the tropical<span class="pagenum"><a name="Page_120" id="Page_120">[Pg 120]</a></span> tendency to showers active in the trade, which +pass mainly to the north of us, or commence north and pass over us, +condensing south while progressing east, the wind may commence blowing +before the body of the storm reaches us, from any point between south by +west and south east, particularly in the summer season and in the +afternoon. When the rain in a storm of this character sets in, in the +night, it will sometimes haul into the S. E., if the focus of attraction +be situated north of us, and so remain until just before the storm is to +break.</p> + +<p>There are, however, a class of southerly summer winds which deserve more +particular notice. For two or three months in the year—say from the +middle of June to the 20th of August—storms on the eastern part of the +continent, except in wet seasons, are rare, and most of our rain is +derived from showers. During these periods belts of drought are frequent, +sometimes in one locality, and sometimes in another, extending with +considerable regularity from W. S. W. to E. N. E. in the course of the +counter-trade, while rain falls in frequent and almost daily showers to +the northward or southward of them. If the daily rains are at the north, +over the belt of drought, S. S. W. and S. W. by S. winds blow, sometimes +with cumuli or scud, during the middle of the day and afternoon, to +underlie the showery counter-trade on the north of the line of drought. +Thus, sometimes nearly every day for several days, the evaporated moisture +of the dry belt will be carried over to increase the store of those who +have a <span class="pagenum"><a name="Page_121" id="Page_121">[Pg 121]</a></span>sufficient supply without. During the latter part of the afternoon +the clouds in the west may look very much like a gathering shower, but the +attractions of the counter-trade fifty or one or two hundred miles to the +north, will absorb them all, and at nightfall the wind will haul to the S. +W. on a line with the counter-trade, and die away.</p> + +<p>If there be a drought on any given line of latitude, and frequent showers +or heavy rains at the south of it, although there may not be a like +surface-wind, with cumuli and fog, blowing from the north toward it, yet a +general, gentle set of the atmosphere, from the N. N. W., or N. W., or +other northerly point, toward the belt of rains, some distance above the +earth, will often be observable, with a barometer continually depressed, +and perhaps a cool atmosphere.</p> + +<p>During set fair weather, when the attracting belt of rains is far north, +on the north shore of Long Island Sound, the wind, like a sea breeze, will +set in gently from about S. S. E. or S. by E. in the forenoon, blowing a +gentle breeze through the day, and hauling to W. S. W. on a line with the +trade at nightfall, and dying away. During a drought I have known this to +happen for seventeen successive days. It is obvious to an attentive +observer that this is the result of the influence of the sun in exciting +the magnetic influence of the earth, and producing a state of the trade +not unlike that which induces the formation of cumuli, and which attracts +the surface atmosphere from the Sound in over the land: for the <i>tendency +to cumulus condensation precedes the breeze</i>, and the breeze is<span class="pagenum"><a name="Page_122" id="Page_122">[Pg 122]</a></span> often +wanting in the hottest days where no such tendency to the formation of +cumuli exists. The same is true of sea breezes elsewhere. They do not blow +in upon some of the hottest surfaces. Where they do exist, they do not +always blow, but are wanting during the hottest days; and careful +observers have identified their appearance with the formation of cumuli, +or other condensation, upon the hills inland. They are not, therefore, the +result of ascending currents of heated air.</p> + +<p>The received theory regarding sea and land breezes is a mistaken one in +another respect. There is no such thing as a land wind corresponding in +force to, and the opposite of, the sea breeze—occasioned by the +comparative warmth of the ocean. These breezes blow mainly within the +trade-wind region. Of course they are either beneath the belt of rains or +the adjoining trades. They are said to be, and doubtless are, most active +and strongly marked on lines of coast, particularly the Malabar coast, and +where the trade-winds are drawing usually from them. In the day-time, when +the action of the sun increases the action of the magnetic currents upon +the land, or there are <i>elevations inland</i> which approach the +counter-trade, and especially if it is elevated near the coast, as the +Malabar coast is by the Ghauts, the attraction of this atmosphere over it +<i>reverses the trade</i>, or inclines it in upon the land, and it blows in +obliquely or perpendicularly, according to the relative trending of the +coast and the direction of the surface-trade. Thus, where <span class="pagenum"><a name="Page_123" id="Page_123">[Pg 123]</a></span>islands are +situated within the range of the trades, the latter will be <i>reversed</i> +during the day on the <i>leeward</i> side, but continue to blow as land winds +during the night. So they are sometimes deflected in upon the land on the +sides, during the day, and in like manner return to their course in the +night. So, too, the north-east trades of Northern Africa, are occasionally +(though feebly where the coast is flat) deflected during the day-time, and +blow in as N. W. winds. Upon the southern coast of Africa the S. E. trade +is deflected, and blows in as a S. W. wind. Upon the south-western coast +of North America, the N. E. trades are deflected in like manner, and so +are the S. E. trades upon the western coast of South America. Where the +coast mountain ranges are very elevated, as upon the western coast of the +American continent, this attracting influence and consequent deflection +extends to a considerable distance seaward, and hence the westerly winds +of California, etc. It must be understood that we are now speaking of the +winds which blow within the range and during the existence of the +trade-winds or the presence of the dry belt—for the trades are not always +perceptible on the land. Captain Fitzroy thus describes the sea breezes of +the western coast of Peru, at 23° south latitude. “The tops of the hills +on the coast of Peru are frequently covered with heavy clouds. The +prevailing winds are from S. S. E. to S. W., seldom stronger than a fresh +breeze, and often very slight. <i>Sometimes during the summer, for three or +four successive days, there is not<span class="pagenum"><a name="Page_124" id="Page_124">[Pg 124]</a></span> a breath of wind, the sky is +beautifully clear, with a nearly vertical sun.</i> On the days that a sea +breeze sets in, it generally commences about ten in the morning, then +light and variable, but gradually increasing till one or two in the +afternoon. From that time a steady breeze prevails till near sunset, when +it begins to die away, and soon after the sun is down there is a calm. +About eight or nine in the evening <i>light winds</i> come off the land, and +continue till sun-rise, when it again becomes calm until the sea breeze +sets in as before.”</p> + +<p>To illustrate this further, I take the following letter from Professor +Espy’s Philosophy of Storms:</p> + +<div class="blockquot"> +<p class="right"><span class="smcap">Clinton Hotel</span>, N. Y., Dec. 20, 1839.</p> + +<p><span class="smcap">To Professor Espy</span>,</p> + +<p><span class="smcap">Dear Sir</span>,—Understanding you are desirous of collecting curious +meteorological facts, I take the liberty of communicating to you what +I saw in the month of December, 1815, at the Island of Owhyhee. I lay +at that island in the Cavrico Bay,<small><a name="f3.1" id="f3.1" href="#f3">[3]</a></small> in which Captain Cook was +killed, three weeks, and every day during that time, very soon after +the sea breeze set in, say about nine o’clock, a cloud began to form +round the lofty conical mountain in that island, in the form of a +ring, as the wooden horizon surrounds the terrestrial artificial +globe, and it soon began to rain in torrents, and continued through +the day. In the evening the sea breeze died away and the rain ceased, +and the cloud soon disappeared, and it remained entirely clear till +after the sea breeze set in next morning. The land breeze prevailed +during the night, and was so cool as to render fires pleasant to the +natives, which I observed they constantly kindled in the evening. I +was particularly struck with the phenomena of the cloud surrounding +the mountain, when none was ever seen in any other part of the sky, +and none then till after the sea breeze set in, in the morning, which +it did with wonderful regularity. The mountain stood in bold relief, +and its top could always be seen from where the<span class="pagenum"><a name="Page_125" id="Page_125">[Pg 125]</a></span> ship lay, above the +cloud, even when it was the densest and blackest, with the lightning +flashing and the thunder rolling, as it did every day. I passed up +through the cloud once, and I know, therefore, how violently it +rains, especially at the lower side of the cloud. This rain never +extends beyond the base of the mountain;<small><a name="f4.1" id="f4.1" href="#f4">[4]</a></small> and all round the horizon +there is eternally a cloudless sky. The dews, however, are very +heavy, and there seems to be no suffering for want of rain. That this +state of things continues all the year, I have no doubt, from what an +American, by name Sears, who had spent four years there, told me; he +had seen no change in regard to the rain.</p> + +<p class="right"><span class="smcap">Caleb Williams.</span></p> + +<p>Providence, R. I.</p></div> + +<p>Similar citations might be made to show that the sea breeze is induced by +the same cause which forms the clouds over the land—that it is frequently +wanting for three or four days under a vertical sun, and that the land +breeze blows gently and not with corresponding force where there is no +surface trade, or where it is deflected, not reversed.</p> + +<p>A succession of showers passing across the country to the north, within +one hundred to one hundred and fifty miles, almost always produces a +southerly wind to the southward of them. There is more that is peculiar +about these belts of showers. Although they consist of large +highly-electrified cumuli, there is a strong tendency to cirro-stratus +condensation in the lower part of the trade over them; and it is that +condensation rather than the cumuli, which attracts the surface atmosphere +from the south. They would be storms, if the atmosphere had not a +summer-tropical tendency to<span class="pagenum"><a name="Page_126" id="Page_126">[Pg 126]</a></span> showers. There is, too, a tendency in these +belts to extend to the south, and it is generally, as far as I have +observed, the extension southerly of those belts, by the formation of new +showers which terminate the “hot spells” or “heated terms” of mid-summer. +The very oppressive and fatal one of the summer of 1853, was, in +character, a type of all—although exceeding them in severity. The first +three or four days were calm, hot, and smoky—an appearance which attends +all similar periods more or less, refracting the red ray of the light, and +giving the sun a peculiar dry-weather, red appearance. (This smoky haze is +usually atmospheric, and occasionally seen even in March, although not +unfrequently fires in the woods fill the air with actual smoke, and very +much increase it, and when this is so, the odor of the smoke is often +perceptible.) Then we began to have a fresh south-west by south breeze in +the day-time, hauling to the south-west, and dying away at nightfall. The +next day, the tendency to condensation and consequent belt of showers +having extended further south and approached nearer to us, the S. S. W. +wind blew <i>fresher</i> toward it, and <i>did not die away at nightfall</i>. During +the evening the reflection of the lightning playing upon the tops of the +thunder clouds, just visible at the north (heat-lightning, it is termed, +because supposed to be unaccompanied by thunder, but in reality lightning +reflected from clouds at too great a distance for the thunder to be +heard), and the continuance of the southerly wind after nightfall, gave +sure evidence of<span class="pagenum"><a name="Page_127" id="Page_127">[Pg 127]</a></span> the coming showers the next day, and an end of the +excessive heat for that time. So ended both of those long-to-be-remembered +“heated terms” of 1853.</p> + +<p>The same is probably true of the interior of the country every where. +Lieutenant Maury, in the course of his investigations, and in order to +ascertain the direction of the winds in the Mississippi valley during +rain, addressed a number of gentlemen, and received their replies, which +are published with his wind and current charts. Several answered, among +other things, that, “whenever the lightning appears to linger at the north +at eventide, rain almost invariably follows speedily; not so in the +south.” Thus it frequently is with us. If, during a hot, dry time, of a +few days continuance, the lightning so lingers in the evening, and the +wind continues to blow <i>fresh</i> from the southward <i>after nightfall</i>, +showers will generally follow within forty-eight hours, most commonly the +next day, and a cool N. N. W. or N. W. wind with a favorable change ensue. +Such, at least, has been the result of my observation for many years.</p> + +<p>Indeed this seems to be the general law in summer in the Mississippi +valley, where the easterly winds are not so common as with us. To +illustrate this further, I copy from a recent work by T. Bassnett, +entitled the “Mechanical Theory of Storms,” two short extracts, showing +the manner in which belts of showers extend southerly, while progressing +north-eastwardly, at Ottawa. The first occurred in August, 1853; the last, +December, 1852. The first was a<span class="pagenum"><a name="Page_128" id="Page_128">[Pg 128]</a></span> belt of showers; the latter would have +been in August, but the lateness of the season changed its character +somewhat, though not entirely, to a more regular rain, especially toward +the close.</p> + +<div class="blockquot"><p>“<span class="smcap">August</span> 6th.—Very fine and clear all day: wind from S. W.; a light +breeze; 8 <span class="smcaplc">P.M.</span> frequent flashes of lightning in the northern sky; 10 +<span class="smcaplc">P.M.</span>, a <i>low bank of dense clouds in north</i>, fringed with cirri, +visible during the flash of the lightning; 12 <span class="smcaplc">P.M.</span>, same continues.</p> + +<p>“7th.—very fine and clear morning; wind S. W. moderate; noon, clouds +accumulating in the northern half of the sky; <i>wind fresher</i>, <i>S. +W.</i>; 3 <span class="smcaplc">P.M.</span>, a clap of thunder over head, and black cumuli in west, +north, and east; 4 <span class="smcaplc">P.M.</span>, much thunder and scattered showers; six +miles west rained very heavily; 6 <span class="smcaplc">P.M.</span>, the heavy clouds passing over +to the south; 10 <span class="smcaplc">P.M.</span>, clear again in north.</p> + +<p>“8th.—Clear all day; wind the same (S. W.); a hazy bank visible all +along on <i>southern horizon</i>.</p> + +<p>“<span class="smcap">December</span> 21st, 1852.—Wind N. E., fine weather.</p> + +<p>“22d.—Thick, hazy morning, wind east, much lighter in S. E. than in +N. W.; 8 <span class="smcaplc">A.M.</span>, a clear arch in S. E. getting more to south; noon, +<i>very black in W. N. W.</i>; above, a broken layer of cirro-cumulus, the +sun visible sometimes through the waves; wind around to S. E., and +fresher; getting thicker all day; 10 <span class="smcaplc">P.M.</span>, <i>wind south, strong</i>; +thunder, lightning, and heavy rain all night, with strong squalls +from south.</p> + +<p>“23d.—Wind S. W., moderate, drizzly day; 10 <span class="smcaplc">P.M.</span>, wind west, and +getting clearer.”</p></div> + +<p>It is obvious that the showers at the north passed east on the evening of +the 6th of August; that new showers, taking the same course, originated in +the north, but more southerly next day, with S. W. wind, and that they +passed east, and others formed successively further south, which passed +over the place of observation late in the afternoon, and that others +formed south and passed east during the night and next day, visible in a +bank on the southern horizon.</p> + +<p>Later or earlier in the spring and autumn, these<span class="pagenum"><a name="Page_129" id="Page_129">[Pg 129]</a></span> brisk afternoon +southerly winds continuing after nightfall, indicate moderate rains from a +rainy belt extending in a similar manner, without the cumuli and thunder +which attend those of mid-summer. I shall recur to this class of showers +and storms when we come to their classification.</p> + +<p>Light surface winds from south-west to west are not often storm-winds, and +are usually those which the trade near the earth draws after it. Sometimes +the trade seems to draw the surface wind from the S. W. and W. S. W. with +considerable rapidity, and some scud a little distance above the earth. +When this is so, it will be found that a storm has passed to the north of +us, or a belt of rains is passing north, which may or may not have +sufficient southern extension to reach us. When there have been heavy +storms at the south in the spring, especially if of snow, the S. W. wind +which the trade draws after it, and which comes from the snowy or chilled +surface, is exceedingly “raw”—that is, damp and chilly, although not +thermometrically very cold. Probably every one has noticed these “<i>raw</i>” +S. W. winds of spring.</p> + +<p>Usually, when storms and showers, which have not a southern lateral +extension, pass off, the trade is very near the earth, and a light S. W. +wind or calm follows for a longer or shorter period. Not unfrequently, +however, our N. E. storms terminate with a S. W. wind, shifting suddenly, +perhaps, just at the close of the storm, during what is sometimes called a +“clearing-off-shower,” or, more frequently, dying gradually away as a N. +E. wind, and coming out<span class="pagenum"><a name="Page_130" id="Page_130">[Pg 130]</a></span> gently from the S. W., following the retreating +cloud of the storm. In such cases it is said to “clear off warm.”</p> + +<p>With us the wind rarely blows from the west, except while slowly hauling +from some southerly point to the N. W. It is probably otherwise east of +the lakes and in some other localities to the north-west.</p> + +<p>Occasionally, and most frequently in March, a W. to W. N. W. wind follows +storms, and blows with considerable severity, with large irregular, +squally masses of scud, and sometimes a gale. Such was the character of +the dry gale which crossed the country, particularly Northern New York, in +March, 1854, doing great damage. These westerly winds are always +accompanied by a continued depression of the barometer, and peculiar, +foggy, scuddy, condensation, and should be distinguished with care from +the regular and peculiar N. W. wind, as they may be, by the continued +depression of the barometer, and the character of the scud. They are +doubtless magnetic storms.</p> + +<p>The remaining surface wind, the N. W., the genuine Boreas of our climate, +the invariable fair-weather wind, is one of great interest. It is unique +and peculiar. It is not the left-hand wind of a rotary gale, and has no +immediate connection with the storm. I have known it blow moderately, +fifteen successive days in winter; rising about ten <span class="smcaplc">A.M.</span>, and dying away +at nightfall. Occasionally, but very rarely indeed, a light wind exists +from the N. W. during a storm, owing probably to a focus of <span class="pagenum"><a name="Page_131" id="Page_131">[Pg 131]</a></span>intensity in +relation to some surface the storm covers, like the focus which exhibits +itself as a clearing-off shower near the close of a storm; but the real +fair-weather Boreas is a different affair altogether. Let us observe with +care its peculiarities; they are instructive.</p> + +<p>1st. It rarely blows with any considerable force beneath the trade while +there are storm clouds, or any considerable condensation in it. It does +not interfere with that reciprocal action which takes place between the +trade and the earth, during approaching or existing storms. I have +frequently seen it with its peculiar scud clouds in the N. W., waiting for +the storm condensation of the trade to pass by, that full of positive +electricity it might commence its sports; rushing and eddying along the +surface, licking up the warm, south polar, electric rain, which stood in +pools upon the ground, or rose in steamy vapor from the surface, and with +its cool breath dry up the muddy roads as no degree of heat can dry them.</p> + +<p>The annexed figure (14) shows the appearance of the northern edge of a +stratus storm cloud, passing off E. N. E. at the close of the storm, which +was “<i>clearing off from the north-west</i>.” It is from a daguerreotype view, +looking W. N. W., taken at eight o’clock in the morning, in the fall of +the year. Near the horizon maybe seen the N. W. scud, forming in the N. W. +wind, which is about to follow the retreating edge of the storm cloud.</p> + +<p>Figure 15 is from a daguerreotype view, taken at eleven o’clock the same +day, when the storm cloud<span class="pagenum"><a name="Page_132" id="Page_132">[Pg 132]</a></span> had passed off and its edge remained visible +only south of the zenith, and the north-east scud had risen up and covered +the northern half of the sky, and the wind was blowing a gale from that +quarter.</p> + +<p> </p> +<p class="center"><strong>Fig. 14.</strong></p> +<div class="figcenter"><img src="images/i0155.jpg" alt="" /></div> +<p> </p> + +<p>Another view was taken about two <span class="smcaplc">P.M.</span> of the same day, when the scud had a +very dark, gloomy appearance—as <i>dark</i> and <i>gloomy</i> as those of a Mexican +norther—too dark to represent by a cut.</p> + +<p>Not unfrequently in a moist summer season, after a day of showers or rain, +which have had an extending formation or lateral extension from north to +south, it will commence blowing in the morning, and encourage the +hay-maker with the hope of fine weather. But often before noon, the milky +stratus condensation above with cumuli below, will appear in the trade;<span class="pagenum"><a name="Page_133" id="Page_133">[Pg 133]</a></span> +the N. W. wind die away and variable airs from the east or south appear, +to be followed toward night by an enlargement of the cumuli and showers. +It rarely, if ever, blows fresh till the storm condensation of the trade +has passed; or continues to blow after that condensation reappears. When +it commences blowing after a storm, and the northern edge of the storm is +not over us, we may frequently see the latter low down in the S. E. +passing eastward.</p> + +<p> </p> +<p class="center"><strong>Fig. 15.</strong></p> +<div class="figcenter"><img src="images/i0156.jpg" alt="" /></div> +<p class="center"><strong>NORTH VIEW.</strong></p> +<p> </p> + +<p>2d. Its scud are peculiar. Every one, probably, has noticed them. They are +distinct, more or less disconnected, irregular, with every form between +those of the easterly scud, cumulus, and stratus, according to the season. +If large, with <i>dark under<span class="pagenum"><a name="Page_134" id="Page_134">[Pg 134]</a></span> surfaces</i>; forming <i>rapidly</i> and as <i>rapidly +dissolving</i>; rarely dropping any rain, sometimes dropping a flurry of +snow, in November or March, oftener than at any other period; sailing away +to the S. E., and casting a traveling shadow as they pass on over the +surface of the earth. Their electricity, particularly when white, is +probably always positive, as that of all whitish clouds is supposed to be.</p> + +<p>3d. <i>It is emphatically a surface wind.</i> The incident storm winds, the N. +E. and S. E., frequently <i>commence blowing</i> under the storm, toward its +point of greatest intensity, <i>up near the line of cirro-stratus +condensation</i>, evidenced by the running scud; or blow there with most +rapidity, and so continue for hours before the whole surface atmosphere +from thence to the earth becomes involved in the movement; and sometimes +without being felt below at all. Not so with the N. W. wind; it <i>begins at +the surface</i> and blows there with more rapidity than above; it seems to be +attracted by the earth; it interposes between the earth and the trade, +wedging the trade up and occupying its place. It blows under at all +seasons of the year, but most readily and strongly from a surface of snow +whose electricity is always positive. Hence it blows most strongly and +<i>continuously</i> when snow has fallen at the north, and prevails during +winter very much in proportion to the extent and continuance of the +covering of snow which invests the earth in that direction. It follows +after storms, and particularly warm rains, during the autumn, winter, and +spring months, which have a lateral southern extension.<span class="pagenum"><a name="Page_135" id="Page_135">[Pg 135]</a></span> Whether it is +increased by the snow from the surface from which it blows, or is caused +by the same magnetic action which causes the great fall of snow, is a +question we shall consider hereafter.</p> + +<p>4th. It does not connect or mingle with the trade current in any way, or +change or divert the course of that current; but interposes between it and +the earth, elevating the trade in proportion to its own volume, above the +influences of the earth (when the trade becomes free from condensation, +and singularly, clear); and raising <i>proportionately</i> the barometer. An +experienced observer can frequently estimate, with considerable accuracy, +the rise of the barometer, by measuring with his eye, (when the clouds +will enable him to do so,) the depth of this interposed N. W. current. The +barometer rarely rises after a storm, for twenty-four or forty-eight hours +if the wind continues at any point from S. W. to W. N. W., but always +rapidly as soon as the genuine N. W. current with any considerable depth +interposes and elevates the trade.</p> + +<p>It will be obvious to every one, I think, certainly, if they will +hereafter study the subject and observe for themselves, that the N. W. +wind does not blow away the storm; and that it follows after it, blowing +over the surface which is uncovered by the storm; rarely, if ever, with +any force when the body of the storm passed south of us; and that it is a +purely surface wind, seemingly attracted by the peculiar magneto-electric +state in which the surface of the earth is left, compared with a snow-clad +surface to the north, by a recent storm, or that peculiar state of the<span class="pagenum"><a name="Page_136" id="Page_136">[Pg 136]</a></span> +trade which is left by the action of the storm. It seems to follow that +magnetic wave which, passing from north to south, acts in its course upon +the counter-trade, producing the storm, or belt of showers, and giving +them their southern lateral extension, and will well repay future +telegraphic investigation. Its electricity is intensely positive—that of +the earth by the action of the storm as intensely negative.</p> + +<p>5th. This N. W. wind occurs in all parts of the northern hemisphere, so +far as we have data to determine, and its corresponding wind from the S. +W. occurs in the southern hemisphere. It is identical with a class of the +northers of the Gulf of Mexico, as a brief analysis of the character of +the latter will show.</p> + +<p>1st. The fall and winter <i>norther</i> is a dry wind without rain or falling +weather—so is our N. W. wind.</p> + +<p>2d. It is preceded by a falling barometer; S. E. scud and rain at the +point where it blows, or to the eastward of it. So is ours when it blows a +gale in the fall and spring months, which bear the nearest resemblance in +climatic character to the periods when the northers blow. With this +distinction, however, that our precedent rains either pass over us or to +the southward, the direction of storms being E. N. E.; their precedent +storms passing over or to the eastward of them as they move more to the +northward.</p> + +<p>3d. It is often preceded by a copious dew; so is ours—such dews often +following light fall rains in our climate, and preceding N. W. wind.</p> + +<p>4th. The most peculiar characteristic, however, is that the barometer +rises rapidly and invariably while<span class="pagenum"><a name="Page_137" id="Page_137">[Pg 137]</a></span> the norther prevails, and very much in +proportion to its violence. The same is true of our genuine N. W. wind, +and is not true <i>of any other wind</i> on this continent which I have +observed or read of.</p> + +<p>5th. While they are thus alike in these respects, they are unlike in no +respect.</p> + +<p>Mr. Redfield has traced them in <i>supposed</i> connection with storms which +continue from that vicinity across the United States to the E. N. E., and +endeavored to connect them with those storms, as the left-hand winds of a +rotary gale. Obviously, I think, they are identical with our N. W. winds +which also <i>follow</i>, indeed, but <i>are distinct from the storms</i>.</p> + +<p>There are a class of northers in the Gulf of Mexico—the “Nortes del Muero +Colorado”—sometimes occurring in the summer months, beginning at N. E., +veering about and settling at N. N. W., and as they decline hauling round +by the west to the southward. These winds correspond precisely with the +hurricane winds of the West Indies, and are doubtless the incident winds +of a storm traveling thence to the N. N. W. precisely as our N. E. or E. +N. E gales are incident storm winds to the N. E. storms of our latitude.</p> + +<p>In this connection we will look at the peculiarities of a West India +hurricane.</p> + +<p>“It is not a little remarkable,” says Mr. Espy, speaking of the storms and +hurricanes of the West Indies, “that all these storms, and <i>all others +which have been traced to the West Indies</i>, traveled N. W. almost at right +angles to the direction of the trade-wind<span class="pagenum"><a name="Page_138" id="Page_138">[Pg 138]</a></span> in those latitudes, but very +nearly, if not exactly, in the direction of an upper current of the air +known to exist there toward the N. W.” Substantially the same facts have +been repeated by Mr. Redfield, and demonstrated by his able +investigations, both there and in the Eastern Pacific, and are confirmed +by the observations of Edwards, Lawson, and others, while residents there. +It is a matter of surprise that gentlemen like Messrs. Redfield and Espy, +who have certainly displayed great ability in the investigations of +meteorological phenomena, should fail to recognize a more intimate +relation between this upper current and the storms they were +investigating, and to detect the general laws which govern both. The +storms and hurricanes of the West Indies are comparatively of small +diameter, and have little advance condensation. When they pass on to the +south-western portion of North America and curve to the N. E., as they +frequently do, they enlarge in front and at the sides, and their advance +condensation, which is not dense enough to drop rain, extends in some +cases from one to three hundred miles; and the storm itself, by the time +it reaches the Alleghanies, may extend one thousand to fifteen hundred +miles, and perhaps in certain magnetic states of the surface, and +occasionally, may cover the entire portion of the continent, from north to +south. Such, probably, was very nearly the extension of the storm +investigated by Professor Loomis. In the West Indies, however, at the +commencement, they vary from twenty to one hundred miles, or possibly +more, in width.</p> + +<p><span class="pagenum"><a name="Page_139" id="Page_139">[Pg 139]</a></span>First, they are preceded by a hot, sultry and oppressive atmosphere—<i>as +are electric storms every where</i>—a peculiar electric state of the earth +and adjacent air.</p> + +<p>Second, the black clouds and lightning which indicate the approaching +hurricane are seen to the S., S. E., and E. S. E., according to the season +of the year, as we see them at the westward. During the rainy season, and +when the storm, as is usual at that period, is small, and the S. E. trade +blows more eastwardly, the wind at the Windward Islands, possibly, may set +in at the north, and back round by the east as it progresses. So Colonel +Reid thinks it sometimes does, at Barbadoes. But when the belt of rains is +south, and the hurricane comes from the south-east, and is larger and more +violent in its action, and the north-east winds prevail, the first effect +is an increase of these trades. Soon, however, the wind hauls to the north +and north-west, in opposition to its course, bearing the same relation to +it that our east and north-east winds bear to storms in the United States; +and the wind hauls around during the passage of the storm to the west, +south-west, and south-east, and at the latter point it clears off. Mr. +Edwards in his History of Jamaica says—and as a resident, his authority +should be decisive as to this Island—“<i>that all hurricanes begin from the +north</i>, veer back to the W. N. W., W., and S. S. W., and when they get +around to the S. E. the foul weather breaks up.” Doubtless the same is +true of the class of northers of which we are speaking on the Gulf of<span class="pagenum"><a name="Page_140" id="Page_140">[Pg 140]</a></span> +Mexico. <i>But with this class the barometer does not rise during the gale, +and in proportion to its length and violence.</i> With the other class of N. +W. winds—the northers of winter—it does.</p> + +<p>The following description of two winter northers, copied from Colonel +Reid’s valuable work, will illustrate what has been said. <i>Precisely such +changes from S. E. rains to N. W. winds, with blue sky and detached dark +clouds—fair-weather N. W. scud—occur every autumn in October and +November</i>, and the falling of the thermometer and rising of the barometer, +after rain, and a change of the wind, are perfectly characteristic.</p> + +<table border="0" cellpadding="0" cellspacing="0" summary="northers"> +<tr><td align="center" class="btrl">1843.</td> + <td align="center" class="btr">Wind.</td> + <td align="center" class="btr">Force.</td> + <td align="center" class="btr">Weather.</td> + <td align="center" class="btr">Bar.</td> + <td align="center" class="btr">Ther.</td> + <td class="btr"> </td></tr> +<tr><td class="btrl">Jan. 30.</td> + <td class="btr"> </td> + <td class="btr"> </td> + <td class="btr"> </td> + <td class="btr"> </td> + <td class="btr"> </td> + <td class="btr"> </td></tr> +<tr><td class="blr"><span class="smcaplc">A.M.</span> 4.</td> + <td class="br">S. S. W.</td> + <td class="br">2</td> + <td class="br">b. c.</td> + <td class="br">29.90</td> + <td class="br">77</td> + <td class="br">Off Tampico.</td></tr> +<tr><td class="blr">Noon.</td> + <td class="br">South.</td> + <td class="br">5</td> + <td class="br">b. c. r.</td> + <td class="br">29.86</td> + <td class="br">76</td> + <td class="br">Lat. 23° 41′ N., Long. 94° 50′ W.</td></tr> +<tr><td class="blr"><span class="smcaplc">P.M.</span> 8.</td> + <td class="br">South.</td> + <td class="br">6</td> + <td class="br">b. c. r.</td> + <td class="br">29.84</td> + <td class="br">76</td> + <td class="br"> </td></tr> +<tr><td class="blr">Jan. 31.</td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td></tr> +<tr><td class="blr"><span class="smcaplc">A.M.</span> 4.</td> + <td class="br">S. Easterly.</td> + <td class="br">3</td> + <td class="br">b. c.</td> + <td class="br">29.90</td> + <td class="br">74</td> + <td class="br">Between 6 and 10 A.M., wind was variable.</td></tr> +<tr><td class="blr">Noon.</td> + <td class="br">N. by W.</td> + <td class="br">9</td> + <td class="br">c. q. w.</td> + <td class="br">29.96</td> + <td class="br">76</td> + <td class="br">Norther commenced at 10 A. M.</td></tr> +<tr><td class="blr"><span class="smcaplc">P.M.</span> 8.</td> + <td class="br">N. N. W.</td> + <td class="br">9</td> + <td class="br">c.</td> + <td class="br">30.09</td> + <td class="br">73</td> + <td class="br">Lat. 22° 36′ N., Long. 95° 48′ W.</td></tr> +<tr><td class="blr">Feb. 1.</td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td></tr> +<tr><td class="blr"><span class="smcaplc">A.M.</span> 4.</td> + <td class="br">N. N. W.</td> + <td class="br">7</td> + <td class="br">c. g.</td> + <td class="br">30.29</td> + <td class="br">63</td> + <td class="br">Lat. 22° 9′ N., Long. 94° 50′ W.</td></tr> +<tr><td class="blr">Noon.</td> + <td class="br">Westerly.</td> + <td class="br">6</td> + <td class="br">c.</td> + <td class="br">30.03</td> + <td class="br">67</td> + <td class="br"> </td></tr> +<tr><td class="blr"><span class="smcaplc">P.M.</span> 8.</td> + <td class="br">Calm.</td> + <td class="br">0</td> + <td class="br">c.</td> + <td class="br">30.26</td> + <td class="br">67</td> + <td class="br"> </td></tr> +<tr><td class="btrl">Feb. 14.</td> + <td class="btr"> </td> + <td class="btr"> </td> + <td class="btr"> </td> + <td class="btr"> </td> + <td class="btr"> </td> + <td class="btr"> </td></tr> +<tr><td class="blr"><span class="smcaplc">A.M.</span> 4.</td> + <td class="br">S. E.</td> + <td class="br">3</td> + <td class="br">b. c. r.</td> + <td class="br">29.66</td> + <td class="br">73</td> + <td class="br">At Sacraficios.</td></tr> +<tr><td class="blr">Noon.</td> + <td class="br">S. W.</td> + <td class="br">4</td> + <td class="br">b. c.</td> + <td class="br">29.62</td> + <td class="br"> </td> + <td class="br">Norther comc’d at 5.30 <span class="smcaplc">P.M.</span></td></tr> +<tr><td class="blr"><span class="smcaplc">P.M.</span> 8.</td> + <td class="br">N. W. by N.</td> + <td class="br">10</td> + <td class="br">c. q. u.</td> + <td class="br">29.72</td> + <td class="br">65</td> + <td class="br"> </td></tr> +<tr><td class="blr">Feb. 15.</td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td></tr> +<tr><td class="blr"><span class="smcaplc">A.M.</span> 4.</td> + <td class="br">N. W. by N.</td> + <td class="br">10</td> + <td class="br">c. q. u.</td> + <td class="br">30.10</td> + <td class="br">61</td> + <td class="br">Gale moderated and again freshened about 8 <span class="smcaplc">A.M.</span></td></tr> +<tr><td class="blr">Noon.</td> + <td class="br">N. W. by N.</td> + <td class="br">10</td> + <td class="br">c. g. q.</td> + <td class="br">30.19</td> + <td class="br">61</td> + <td class="br"> </td></tr> +<tr><td class="blr"><span class="smcaplc">P.M.</span> 8.</td> + <td class="br">N. W.</td> + <td class="br">4</td> + <td class="br">c. g.</td> + <td class="br">30.20</td> + <td class="br">65</td> + <td class="br"> </td></tr> +<tr><td class="blr">Feb. 16.</td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td></tr> +<tr><td class="blr"><span class="smcaplc">A.M.</span> 4.</td> + <td class="br">N. W.</td> + <td class="br">3</td> + <td class="br">q.</td> + <td class="br">30.18</td> + <td class="br">62</td> + <td class="br"> </td></tr> +<tr><td class="bblr"><span class="smcaplc">P.M.</span> 8.</td> + <td class="bbr">N. N. W.</td> + <td class="bbr">2</td> + <td class="bbr">c. g.</td> + <td class="bbr">30.21</td> + <td class="bbr">66</td> + <td class="bbr"> </td></tr></table> + +<div class="note"> +<p class="center">b. indicates blue sky—c. detached clouds—r. rain—v. visibility of objects—q. +squalls—w. wet dew—u. ugly threatening appearance—g. gloomy weather.</p></div> + +<p><span class="pagenum"><a name="Page_141" id="Page_141">[Pg 141]</a></span>The exact counterpart of the first norther may be observed with us every +fall. On the 30th January, with a rising thermometer and falling +barometer, there was rain at midday. The night following was moist—the +next day, about ten <span class="smcaplc">A.M.</span>, the wind came out N. W., with squalls and gloomy +weather, a falling thermometer, and rising barometer.</p> + +<p>The norther of Feb. 14th differed from the other only in regard to the +time of the day when it commenced; the order of events was the same. The +rain fell in the night—it cleared off early in the day, and the norther +followed in the afternoon. This also is frequently the case with us, as +every one may observe.</p> + +<p>This brief notice of the surface winds of our climate would be incomplete +without a description of those of the thunder-gust and tornado.</p> + +<p>The former is exceedingly simple. The showers, which are accompanied with +much wind, form suddenly in hot weather, and have a considerable advance +condensation (frequently with obvious lateral internal action), extending +eastwardly from the line of smooth cloud from which the rain is falling, +or rather where the falling rain obscures the inequalities of the cloud. +<i>The gust is never felt until the advancing condensation has passed over +us</i>, when it takes the place of the gentle easterly breeze which +previously set toward the shower. <i>The gust ceases as soon as the cloud +has passed.</i> It is obviously the result of the inducing and attracting +influence of the cloud upon the atmosphere near the surface of the earth +as it passes over it. Let the reader watch attentively this<span class="pagenum"><a name="Page_142" id="Page_142">[Pg 142]</a></span> advance +condensation, from its eastern edge to the line of smooth cloud and +falling rain, and he will understand at a glance this internal action of +gust-clouds. The whole phenomena are simple and intelligible. A cloud +approaching from a westerly point, dark and irregular from its eastern +edge to the line of falling rain, where it appears smooth and of a light +color; wind from the east blowing gently toward it, till the condensation +is over us; then the gust following the cloud; then the rain, and in a few +minutes the cloud, and wind, and rain have passed on to the east, and +“sunshine” returns.</p> + +<p>The tornado, as it is termed when it occurs upon land, “spout,” if on the +water, is sometimes of a different character, and as it undoubtedly had +great influence in inducing the gyrating theory of Mr. Redfield, and the +aspiratory theory of Mr. Espy, and has been cited by both in support of +their respective theories, it deserves a more particular notice. There are +several marked peculiarities attending it which determine its character.</p> + +<p>1st. It occurs during a <i>peculiarly sultry and electric</i> state of the +trade and surface atmosphere, and at a time when thunder showers are +prevailing in and around the locality, and at every period of the year +when such a state of the atmosphere exists. One recently occurred in +Brandon, Ohio, in midwinter.</p> + +<p>2d. There is always a cloud above, but very near the earth, between which +and the earth the tornado forms and rages. It is usually described as a +black cloud, ranging about 1000 feet or less above the<span class="pagenum"><a name="Page_143" id="Page_143">[Pg 143]</a></span> earth, often with +a whitish shaped cone projecting from it, and forming a connection with +the earth; at intervals rising and breaking the connection, and again +descending and renewing it with devastating energy. Its width at the +surface varies from forty to one hundred and eighty rods—the most usual +width being from sixty to ninety rods. Sometimes when still wider, they +have more the character of thunder-gusts, and are brightly luminous.</p> + +<p>3d. Two motions are usually visible, one ascending one near the earth and +in the middle, and a gyratory one around the other. The latter is rarely +felt, or its effects observed, near the earth. Occasionally, and at +intervals, objects are thrown obliquely backward by it.</p> + +<p>4th. It is composed, at the surface of the earth, of <i>two lateral +currents</i>, a northerly and southerly one, varying in direction, but +normally at right angles in most cases, although not always, with its +course of progression, extending from the extreme limits of its track to +the axis; which currents are most distinctly defined toward the center, +and upward. These currents prostrate trees, or elevate and remove every +thing in their way which is detached and movable. There does not seem to +be any current in advance of these lateral ones tending toward the +tornado, save in rare and excepted cases, and then owing to the make of +the ground or the irregular action of the currents; nor any following, +except that made by the curving of the lateral currents toward the center +of the spout as it moves on, and perhaps<span class="pagenum"><a name="Page_144" id="Page_144">[Pg 144]</a></span> a tendency of the air to follow +and supply the place of that which has been carried upward and forward, +like that of water following the stern of a vessel. The south current is +always the strongest, and often a little in advance of the other, and +covers the greatest area. The proportion of the two currents to each other +is much the same that the S. E. trades bear to the N. E. This excess in +volume and strength of the southerly current will explain the +irregularities in most cases, and the fact that objects are so often +<i>taken up and carried from the south to the north side</i>, and so rarely +from the north and carried south of the axis. These irregularities are +such as attend all violent forces, and something can be found which will +favor almost any theory; but the two lateral currents appear always to be +the principal actors, except, perhaps, when it widens out and assumes more +the character of a straightforward gust. See a collection by Professor +Loomis, American Journal of Science, vol. xliii. p. 278.</p> + +<p>The following diagram is a section of the New Haven tornado, from +Professor Olmstead’s map accompanying his article in the “American Journal +of Science and Art,” vol. 37. p. 340.</p> + +<p>The manner in which the main currents flow is shown by their early and +unresisted effect in a cornfield, as represented by the dotted lines. The +direction in which the fragments of buildings were carried by the greater +power of the southerly currents is shown also. And so is this irregular +action, where a part of the southerly current broke through the<span class="pagenum"><a name="Page_145" id="Page_145">[Pg 145]</a></span> northerly +one, and prostrated two or three trees backward on the north side of the +axis.</p> + +<p> </p> +<p class="center"><strong>Fig. 16.</strong></p> +<div class="figcenter"><img src="images/i0168.jpg" alt="" /></div> +<p> </p> + +<p>5th. This cloud, and its spout, move generally with the course of the +counter-trade in the locality—<i>i. e.</i>, from some point between S. W. and +W., to the eastward, but occasionally a little south of east, deflected by +the magnetic wave beneath the belt of showers.</p> + +<p>6th. Several exceedingly instructive particulars have been observed and +recorded.</p> + +<p><i>a</i>. <i>No wind is felt outside of the track</i>, as those assert who have +stood very near it, and its effects show.</p> + +<p><i>b</i>. The track is often as distinctly marked, where it passed through a +wood, as if the grubbers had been there with their axes to open a path for +a rail-road. The branches of the trees, projecting within its limits,<span class="pagenum"><a name="Page_146" id="Page_146">[Pg 146]</a></span> are +found twisted and broken off, or stripped of their leaves, while not a +leaf is disturbed at the distance of a foot or two on the opposite side of +the tree, and outside of the track.</p> + +<p><i>c</i>. As the spout passes over water, the latter seems to <i>boil up</i> and +<i>rise to meet it</i>, and <i>flow up</i> its trunk in a <i>continued stream</i>.</p> + +<p><i>d</i>. As it passes over the land, and over buildings, fences, and other +movable things, they appear to <i>shoot up</i>, instantaneously, as it were, +into the air, and into fragments. If buildings are not destroyed or +removed, the doors may be burst open <i>on the leeward side</i>, and gable ends +<i>snatched out</i>, and roofs taken off on the <i>same side</i>, while that portion +of the building which is to the windward remains unaffected.</p> + +<p><i>e</i>. Articles of clothing, and other light articles, have been carried out +of buildings through open doors, or chimneys, or holes made in the roofs, +and to a great distance, without <i>any opening</i> being made for the air to +<i>blow</i> in.</p> + +<p><i>f</i>. If there be a discharge of electricity up the spout from the earth, +like that of lightning, the intense action ceases for a time or entirely.</p> + +<p><i>g</i>. Vegetation in the track is often scorched and killed, and so of the +leaves on one side of a tree, which is within the track, while those on +the other side, and without the track remain unaffected. (Espy’s +Philosophy of Storms, 359, cited from Peltier.)</p> + +<p><i>h</i>. The active agent whatever it is, has been known to <i>seize hold of a +chain attached to a plow</i> and <i>draw the plow about, turning the stiff sod +for a considerable<span class="pagenum"><a name="Page_147" id="Page_147">[Pg 147]</a></span> distance</i>. (See Loomis on the tornado at Stow, Ohio, +American Journal of Science, vol. xxxiii. p. 368.)</p> + +<p><i>i</i>. In passing over ponds, the spout has taken up all the water and fish, +and scattered them in every direction, and to a great distance.</p> + +<p><i>j</i>. The barometer falls very little during the passage of the spout. (See +the Natchez hurricane of 1827, Espy page 337.) Not more than it +<i>frequently</i> does during gentle showers.</p> + +<p><i>k</i>. Persons have been taken up, carried some distance, and if not +projected against some object in the way, or some object against them, +have usually been <i>set down gently and uninjured</i>.</p> + +<p><i>l</i>. Buildings which stood upon posts, with a free passage for the air +under them, although in the path of the tornado, escaped undisturbed. +(Olmstead’s account of the New Haven tornado, American Journal of Science, +vol. xxxvii. p 340.)</p> + +<p><i>m</i>. A chisel taken from a chest of tools, and stuck fast in the wall of +the house. (Ibid.)</p> + +<p><i>n</i>. Fowls have had all their feathers stripped from them in an instant +and run about naked but uninjured.<small><a name="f5.1" id="f5.1" href="#f5">[5]</a></small></p> + +<p><i>o</i>. Articles of furniture, etc., have been found torn in pieces by +antagonistic forces.</p> + +<p><i>p</i>. Frames taken from looking-glasses without breaking the glass. Nails +drawn from the roofs of houses without disturbing the tiles.</p> + +<p><span class="pagenum"><a name="Page_148" id="Page_148">[Pg 148]</a></span><i>q</i>. Hinges taken from doors—<i>mud taken from the bed of a stream</i> (the +water being first removed), and let down on a house covering it +completely—a farmer taken up from his wagon and carried thirty rods, his +horses carried an equal distance in another direction, <i>the harness +stripped from them</i>, and the wagon carried off also, <i>one wheel not found +at all</i>. (American Journal of Science, vol. xxxvii. p. 93.)</p> + +<p>Pieces of timber, boards, and clapboard, driven into the side of a hill, +<i>as no force of powder could drive them, etc., etc.</i></p> + +<p>Now to my mind, these circumstances indicate clearly, that it is not wind, +<i>i. e.</i>, mere currents of air, which produces the effect, but that a +<i>continuous current</i> or <i>stream of electricity</i> from the earth to the +cloud exists, and carries with it from near the earth, such articles as +are movable: That this stream collects from the <i>northerly</i> and +<i>southerly</i> side upon the <i>magnetic meridian</i>, in <i>two currents</i> with +<i>polarity</i>, which meet in their passage up at the center; curving toward +the center in the posterior part as the spout moves on, when acting in a +normal manner, and making the “<i>law of curvature</i>” observed: That no +conceivable movement of the air alone in such limited spaces could produce +such effects; or if so, that no agent but electricity could so move the +air: That the air in a building could not shoot the roof upward, and into +fragments; much less could the air in a cellar by any conceivable force, +be made to elevate <i>or shoot up</i> the entire house, and its inmates, and +contents—effects so totally unlike what takes<span class="pagenum"><a name="Page_149" id="Page_149">[Pg 149]</a></span> place in gales, +hurricanes, and typhoons: That elastic free air never did nor could take +hold of the plow chain, and plow up the ground; or scorch and kill the +vegetation; or twist the <i>limbs</i> from one side of a tree, while the most +delicate leaves on the other, and within two or three feet, remained +unaffected and undisturbed; or pick the chickens: That even if the +expansion of the air could produce these effects—if a sudden vacuum were +produced—<i>nothing but currents of electricity could produce the sudden +vacuum</i>, by removing the air above.</p> + +<p>It is well settled that atmospheric electricity can and does flow in +currents with light, by experiments in relation to the brush discharge, +etc. That it may do so without light or disruptive discharge, and in a +stream, or as it is termed, by convection, with the force and effect seen +in the tornado, is perfectly consistent with what we know of it—and it +is, I think clearly evinced that such is the character of the phenomena, +by the fact that a sudden powerful <i>disruptive</i> discharge, <i>with light, up +the spout</i>, produces an instantaneous partial or total suspension of its +action; to be renewed as the cloud passes over <i>another</i> and more highly +charged <i>portion</i> of the <i>earth’s surface</i>. Peltier gives instances where +the spout has been entirely and instantaneously destroyed by such a sudden +and powerful discharge of electricity; marking the spot where it was so +destroyed by a large hole in the earth, from which the discharge issued. +And in fact these tornados are often steadily luminous,<span class="pagenum"><a name="Page_150" id="Page_150">[Pg 150]</a></span> and so much so, +when they occur in the night, as to enable persons to read without +difficulty.</p> + +<p>The lateral inward and upward currents, are accompanied, after they meet +and unite, or seem to unite, by gyratory or circular ones. How are they +produced? This question can only be answered by analogy. No permanent +impressions are left by the circular currents, except to a limited extent, +and in occasional instances; and observation of them has been, and must +necessarily be limited and uncertain. I have witnessed one or two on a +moderate scale; but owing to the suddenness of their passage, and the +confusion of the objects taken up, it was difficult to determine what the +circular currents were. When the southerly current is much the strongest, +it appears sometimes to cross the axis, and curve round the northerly one. +Perhaps this may be all the curving that really takes place, except at the +posterior part of the axis, for evidence of a curving on the south of the +axis is rarely, if ever seen.</p> + +<p>Assuming, however, that the main currents unite and form one from the +earth to the cloud, <i>induced</i> circular currents would be in perfect +keeping with the known laws of electricity. Such currents, and with +magnetic properties, are always induced by powerful currents of voltaic +electricity passing through wires. And doubtless <i>in all cases</i> powerful +currents of electricity <i>induce attendant circular currents</i>. This may +account for the external gyration of the spout.</p> + +<p>Or it may be that the two lateral currents of air<span class="pagenum"><a name="Page_151" id="Page_151">[Pg 151]</a></span> which attend the +currents of electricity, do not unite; having opposite polarity, but pass +by and around each other, in connection with the circular magnetic +currents. Future observation and perhaps experimental research will +determine this. But it may not be accomplished by the present generation; +for the belief that tornados are mere whirlwinds, produced by the action +of the sun in heating the land, is adhered to, notwithstanding they cross +the intense magnetic area of Ohio in mid-winter, and seems to be +ineradicable.</p> + +<p>The proportions of different winds vary in different localities. For the +benefit of those who are curious, I copy a table from an able compilation +by Professor Coffin, published by the Smithsonian Institute, showing the +proportion of the winds at New Haven (the station nearest to me). It will +be noticed that during the year the N. W. winds blow the greatest number +of days; the S. W. next; the N. E. and S. E. less than either, and about +equal. It may be observed that the two latter bear about the same +proportion to the whole, that our number of cloudy and stormy days, +averaging about ninety, bear to the whole number of days in the year.</p> + +<table border="0" cellpadding="0" cellspacing="0" summary="days"> +<tr><td class="btrl" align="center">Course.</td> + <td class="btr" align="center">1804.</td> + <td class="btr" align="center">1811.</td> + <td class="btr" align="center">1812.</td> + <td class="btr" align="center">1813.</td> + <td class="btr" align="center">Total.</td></tr> +<tr><td class="btrl" align="center">N.</td> + <td class="btr" align="right">143</td> + <td class="btr" align="right">105</td> + <td class="btr" align="right">90</td> + <td class="btr" align="right">111</td> + <td class="btr" align="right">449</td></tr> +<tr><td class="blr" align="center">N. E.</td> + <td class="br" align="right">99</td> + <td class="br" align="right">207</td> + <td class="br" align="right">138</td> + <td class="br" align="right">138</td> + <td class="br" align="right">582</td></tr> +<tr><td class="blr" align="center">E.</td> + <td class="br" align="right">33</td> + <td class="br" align="right">18</td> + <td class="br" align="right">22</td> + <td class="br" align="right">23</td> + <td class="br" align="right">96</td></tr> +<tr><td class="blr" align="center">S. E.</td> + <td class="br" align="right">131</td> + <td class="br" align="right">108</td> + <td class="br" align="right">135</td> + <td class="br" align="right">110</td> + <td class="br" align="right">484</td></tr> +<tr><td class="blr" align="center">S.</td> + <td class="br" align="right">58</td> + <td class="br" align="right">69</td> + <td class="br" align="right">113</td> + <td class="br" align="right">80</td> + <td class="br" align="right">320</td></tr> +<tr><td class="blr" align="center">S. W.</td> + <td class="br" align="right">224</td> + <td class="br" align="right">255</td> + <td class="br" align="right">153</td> + <td class="br" align="right">261</td> + <td class="br" align="right">893</td></tr> +<tr><td class="blr" align="center">W.</td> + <td class="br" align="right">81</td> + <td class="br" align="right">69</td> + <td class="br" align="right">102</td> + <td class="br" align="right">57</td> + <td class="br" align="right">309</td></tr> +<tr><td class="bblr" align="center">N. W.</td> + <td class="bbr" align="right">329</td> + <td class="bbr" align="right">264</td> + <td class="bbr" align="right">345</td> + <td class="bbr" align="right">315</td> + <td class="bbr" align="right">1253</td></tr></table> + +<p><span class="pagenum"><a name="Page_152" id="Page_152">[Pg 152]</a></span>This work of Mr. Coffin has been brought to my notice since the foregoing +pages were written. The facts embodied in it will be found to comport with +what I have observed and stated. In relation to the proportionate number +of days in the year during which the wind blows from the different points +of the compass at the several stations it is very full and able.</p> + +<p>But it has cardinal defects. It does not show the <i>main currents</i> of the +atmosphere. It treats the surface-winds, which are incidental, as +principals. The direction of the main currents is indeed shown frequently +by the mean course of the surface winds, but not uniformly or +intelligibly. Nor does it distinguish between the fair weather and storm +winds; nor always between the trade winds during their northern transit, +and the variable winds north of the trade-wind region. Hence, the +deductions derived from it disclose no general system, and sustain no +theory, although many very important facts appear. Some of these, +Professor Coffin found it difficult to reconcile with received theories, +or satisfactorily explain. For instance, he found the prevailing winds of +the United States, in Louisiana and Texas, S. and S. E.; in western +Arkansas, and Missouri, southerly, and in Iowa and Wisconsin, S. W., +forming a curve, and evidently connected together.</p> + +<p>Thus, alluding to the winds west of the Mississippi, and between the +parallels of 36° and 60°, he says:</p> + +<div class="blockquot"><p>“On the American continent, west of the Mississippi, there appears to +be more diversity in the mean direction of the wind, yet here it is<span class="pagenum"><a name="Page_153" id="Page_153">[Pg 153]</a></span> +westerly at sixteen stations out of twenty, from which observations +have been obtained. The most peculiar feature in this region, is the +<i>line</i> of southerly winds on the western borders of Arkansas and +Missouri. It seems to form a connecting link between the winds of +this zone and the south-easterly ones that we find south of it; and, +in some degree, to favor an idea that has been advanced, that there +is a vast eddy, extending from the western shore of the Gulf of +Mexico, to the eastern shore of the Atlantic; that the easterly +trade-winds of the Atlantic Ocean, when they strike the American +continent, veer northwardly, and then N. E., and thus recross the +Atlantic, and follow down the coast of Portugal and Africa, till they +complete the circuit.”</p></div> + +<p>This mean prevalence of the curving winds indicates the course of the +western portion of the concentrated counter-trade, of which we have so +fully spoken, and to which that portion owes its rains and fertility. +Doubtless the curve would have been traced somewhat further west, if +observations had been obtained from more westerly stations.</p> + +<p>The idea of an eddy, to which Professor Coffin alludes, is of course +unsound; that of a counter-trade, most fully confirmed; the curve +corresponding with that of the regular rains and fertility as they are +known to exist.</p> + +<p>Professor Coffin is a believer in the generally-received theory of +rarefaction, as the cause of all winds. His work is published by the +Smithsonian Institution, and the theory is, so far forth, nationalized. +But he found it very difficult to reconcile all the facts he obtained, +with the theory, and, possessing a truth-loving mind, he frankly admits +it. Alluding to the prevalence of N. E. winds off the coast of Africa in +the summer months, as shown by certain numbered wind-roses, he says:</p> + +<div class="blockquot"><p><span class="pagenum"><a name="Page_154" id="Page_154">[Pg 154]</a></span>“Nos. 81, 83, 86, and 91, have caused me much perplexity. The arrows +for the warmer months evidently indicate a point of rarefaction +situated to the <i>south</i> or <i>south-west</i>, and yet all the observations +from which they were computed were taken within a few hundred miles +of the African coast and desert of Sahara; a region, the annual range +of whose temperature must be exceedingly great. The only way in which +I can account for a fact so astonishing, is, by supposing the +deflecting forces at these numbers to be secondary to the influence +which we see so strongly marked in Nos. 88, 89, and 90. Let us, then, +first devote our attention to these.”</p></div> + +<p>(We have not space for the map of Professor Coffin, nor is it necessary to +insert it. The numbers 81, 83, 86, and 91, refer to respective portions of +the Atlantic, west of Africa, North of the Cape de Verdes, of 5° of +latitude each, where the N. E. trades are drawing off from the coast. The +Nos. 88, 89, and 90 refer to like portions <i>below</i> the Cape de Verde, +where the S. W. monsoons are found under the rainy belt; and the +explanation of the distinguished author is an attempt to account for the +blowing of the trades <i>from</i> Sahara, by supposing them connected with the +monsoons further south, which seem to blow toward it.)</p> + +<div class="blockquot"><p>“The intense heat of the Great Desert rarefies the air exceedingly +from June to October, inclusive, and hence the arrows of unparalleled +length (Plate XII.),” (showing the monsoon winds below the Cape de +Verdes,) “pointing toward it during those months, the longest being +longer than that which represents the most uniform of the +trade-winds, in the ratio of 104 to 89. The influence of this +rarefaction is sufficient to curve the powerful current of the +trade-winds in the manner exhibited on Plate VII. Nos. 89 and 90, and +to produce the not less remarkable change in No. 88, holding the +current back and retarding it, so that its progressive motion in the +<i>three</i> months of July, August, and September united, hardly exceeds +that during any <i>one</i> of the colder months of the year. But while +this is so, the trades on the western side of the Atlantic are +pursuing nearly their regular track, being but<span class="pagenum"><a name="Page_155" id="Page_155">[Pg 155]</a></span> slightly affected by +these influences. As a consequence, the latter must leave, as it +were, a partial vacuum behind them, which is filled by air flowing in +from the north-east and south-east. This will account for the seeming +anomaly of having a somewhat strong deflecting force directed toward +mid-ocean, in the hottest part of the year, as in the numbers above +referred to. <i>And yet it may be very naturally asked, Why does not +the air from these parts supply the Great Desert directly, instead of +taking a circuitous route to supply the region that supplies it? A +question which, I confess, it seems difficult to answer.</i>”</p></div> + +<p>(The italicization in the foregoing extract is mine).</p> + +<p>Here the worthy professor finds a fact inconsistent with the theory of +rarefaction—viz.: that the winds blow off shore, and toward mid-ocean, +opposite Sahara, and he is “perplexed and astonished.” The theory, +however, must be maintained, and one of those modifying hypotheses which +have made meteorology such a complicated piece of patch-work, must be +invented; some “deflecting forces” found. There is the Great Desert, +bordering upon the ocean, north of the Cape de Verde Islands, for a +distance of six hundred miles, widening as it extends inland, whose +temperature, as he says, “<i>must be exceedingly great</i>;” and doubtless is +so, and yet the air, instead of blowing in upon it in a hurricane, is +actually drawing off from it, and blowing towards the S. W., where the +water and air do not rise above 84°. Well may he be “perplexed and +astonished.”</p> + +<p>Turning south, however, to the distance of five hundred miles or more, he +finds the S. W. monsoon winds, which in those months blow under the belt +of rains, toward the land, in the direction of, but at a great distance +from, Sahara. It is an easy matter<span class="pagenum"><a name="Page_156" id="Page_156">[Pg 156]</a></span> to suppose that they reach the Great +Desert and supply its vortex of rarefaction, inasmuch as they blow in a +direction toward it, and distance is no impediment to supposition.</p> + +<p>Then it is necessary to <i>suppose</i> that the S. E. and N. E. trades, at the +south-west, draw so strongly to the westward as to create a partial vacuum +to the S. W. of Sahara, which is filled by the winds which draw off shore, +and then we have the supply brought from the distance of five hundred +miles or more, by an ascending vortex, which creates a vacuum, and the air +near the vortex taken away in <i>another</i> direction by a <i>partial</i> vacuum; +and so an ascending <i>vortex</i>, which creates a vacuum is supplied from a +distance, and a <i>partial vacuum</i> at a distance is supplied by the air near +the perfect vacuum. Such an idea of a supply by a circuitous route, and +secondary influence, is not very philosophical, to say the least, and +Professor Coffin feels it; and to the question, Why is it so? which, he +says, may very naturally be asked, he confesses there is no answer. And +there would be none, even if his suppositions were based upon facts. But +other questions might be asked equally difficult to be answered, viz.:</p> + +<p>1st. Is there any rarefaction which can draw the trades to the west, and +in that particular locality, in opposition to the supposed vortex of +Sahara, by creating a <i>partial vacuum</i>?</p> + +<p>2d. Are they in fact so drawn?</p> + +<p>3d. Do the S. W. winds, south of the Cape de Verdes, and <i>under the rainy +belt</i>, which in the summer<span class="pagenum"><a name="Page_157" id="Page_157">[Pg 157]</a></span> months extend up to these islands, <i>reach the +desert at all</i>?</p> + +<p>These are pertinent questions, <i>and every one of them must be answered in +the negative</i>. The hypothesis is without foundation, and Professor’s +Coffin’s perplexity and astonishment must remain, until he abandons the +theory of rarefaction entirely. The winds which so perplex him are nothing +but the regular N. E. trades, made to originate on the coast and continent +of Africa, in summer, by the northern transit of the whole machinery. They +not only draw off from the desert coast, but they <i>blow over the desert +itself</i> on to the ocean, and into the rainy belt upon the land, as we have +already seen, and the supposed vortex of rarefaction does not exist.</p> + +<p>That the monsoons do not reach the desert is demonstrated by the tables of +Professor Coffin, and to set it at rest we will make the necessary +extracts. Commencing with the region from the equator to 5° N., and from +10° to 55° W. longitude, we have the observed winds in proportion, as +follows, for July and August—the south-east trades prevailing, inasmuch +as the belt of rains is at this season situated further north.</p> + +<p class="center"><span class="smcap">Latitude 0° To 5°, Longitude From Greenwich 10° To 55°.</span></p> + +<table border="0" cellpadding="0" cellspacing="0" summary="latitude"> +<tr><td class="btrl" align="center">Course.</td> + <td class="btr" align="center">July.</td> + <td class="btr" align="center">August.</td> + <td class="btr" align="center">Course.</td> + <td class="btr" align="center">July.</td> + <td class="btr" align="center">August.</td></tr> +<tr><td align="center" class="btrl">North.</td> + <td class="btr" align="right">0</td> + <td class="btr" align="right">0</td> + <td align="center" class="btr">S. S. W.</td> + <td class="btr" align="right">54</td> + <td class="btr" align="right">111</td></tr> +<tr><td align="center" class="blr">N. N. E.</td> + <td class="br" align="right">8</td> + <td class="br" align="right">2</td> + <td align="center" class="br">S. W.</td> + <td class="br" align="right">1</td> + <td class="br" align="right">29</td></tr> +<tr><td align="center" class="blr">N. E.</td> + <td class="br" align="right">6</td> + <td class="br" align="right">2</td> + <td align="center" class="br">W. S. W.</td> + <td class="br" align="right">6</td> + <td class="br" align="right">19</td></tr> +<tr><td align="center" class="blr">E. N. E.</td> + <td class="br" align="right">27</td> + <td class="br" align="right">16</td> + <td align="center" class="br">West.</td> + <td class="br" align="right">2</td> + <td class="br" align="right">9</td></tr> +<tr><td align="center" class="blr">East.</td> + <td class="br" align="right">31</td> + <td class="br" align="right">20</td> + <td align="center" class="br">W. N. W.</td> + <td class="br" align="right">1</td> + <td class="br" align="right">6</td></tr> +<tr><td align="center" class="blr">E. S. E.</td> + <td class="br" align="right">120</td> + <td class="br" align="right">96</td> + <td align="center" class="br">N. W.</td> + <td class="br" align="right">1</td> + <td class="br" align="right">0</td></tr> +<tr><td align="center" class="blr">S. E.</td> + <td class="br" align="right">216</td> + <td class="br" align="right">276</td> + <td align="center" class="br">N. N. W.</td> + <td class="br" align="right">0</td> + <td class="br" align="right">2</td></tr> +<tr><td align="center" class="blr">S. S. E.</td> + <td class="br" align="right">218</td> + <td class="br" align="right">443</td> + <td align="center" class="bbr">Calm.</td> + <td class="bbr" align="right">8</td> + <td class="bbr" align="right">4</td></tr> +<tr><td align="center" class="bblr">South.</td> + <td class="bbr" align="right">69</td> + <td class="bbr" align="right">279</td> + <td class="bbr">Total</td> + <td class="bbr" align="right">768</td> + <td class="bbr" align="right">1,314</td></tr></table> + + +<p><span class="pagenum"><a name="Page_158" id="Page_158">[Pg 158]</a></span>Here, it is evident that the S. E. trades are the prevailing winds, but +their course is variable.</p> + +<p>Ascending to the region between 5° and 10° north latitude, and 10° to 55° +west longitude, the northern part of which at this season is covered by +the rainy belt; we find the monsoon, the S., S. S. W., and S. W. winds, +the prevailing ones in August, although the winds are variable, as usual +under the rainy belt.</p> + +<table border="0" cellpadding="0" cellspacing="0" summary="monsoon"> +<tr><td class="btrl" align="center">Course.</td> + <td class="btr" align="center">July.</td> + <td class="btr" align="center">August.</td> + <td class="btr" align="center">Course.</td> + <td class="btr" align="center">July.</td> + <td class="btr" align="center">August.</td></tr> +<tr><td align="center" class="btrl">North.</td> + <td class="btr" align="right">19</td> + <td class="btr" align="right">6</td> + <td align="center" class="btr">S. S. W.</td> + <td class="btr" align="right">188</td> + <td class="btr" align="right">368</td></tr> +<tr><td align="center" class="blr">N. N. E.</td> + <td class="br" align="right">26</td> + <td class="br" align="right">11</td> + <td align="center" class="br">S. W.</td> + <td class="br" align="right">63</td> + <td class="br" align="right">94</td></tr> +<tr><td align="center" class="blr">N. E.</td> + <td class="br" align="right">194</td> + <td class="br" align="right">32</td> + <td align="center" class="br">W. S. W.</td> + <td class="br" align="right">73</td> + <td class="br" align="right">93</td></tr> +<tr><td align="center" class="blr">E. N. E.</td> + <td class="br" align="right">30</td> + <td class="br" align="right">16</td> + <td align="center" class="br">West.</td> + <td class="br" align="right">33</td> + <td class="br" align="right">48</td></tr> +<tr><td align="center" class="blr">East.</td> + <td class="br" align="right">45</td> + <td class="br" align="right">29</td> + <td align="center" class="br">W. N. W.</td> + <td class="br" align="right">30</td> + <td class="br" align="right">18</td></tr> +<tr><td align="center" class="blr">E. S. E.</td> + <td class="br" align="right">36</td> + <td class="br" align="right">40</td> + <td align="center" class="br">N. W.</td> + <td class="br" align="right">21</td> + <td class="br" align="right">9</td></tr> +<tr><td align="center" class="blr">S. E.</td> + <td class="br" align="right">93</td> + <td class="br" align="right">53</td> + <td align="center" class="br">N. N. W.</td> + <td class="br" align="right">17</td> + <td class="br" align="right">13</td></tr> +<tr><td align="center" class="blr">S. S. E.</td> + <td class="br" align="right">225</td> + <td class="br" align="right">307</td> + <td align="center" class="bbr">Calm.</td> + <td class="bbr" align="right">109</td> + <td class="bbr" align="right">74</td></tr> +<tr><td align="center" class="bblr">South.</td> + <td class="bbr" align="right">239</td> + <td class="bbr" align="right">514</td> + <td class="bbr">Total</td> + <td class="bbr" align="right">1,351</td> + <td class="bbr" align="right">1,725</td></tr></table> + + +<p>Ascending to the region of 10° to 15° north latitude, and 15° to 45° west +longitude, we find the winds exceedingly variable, and the monsoons +diminished remarkably. If Professor Coffin’s theory was correct, they +should increase as they approach the desert; but they in fact, diminish, +and the N. E. trades are found at the north portion.</p> + +<table border="0" cellpadding="0" cellspacing="0" summary="course"> +<tr><td class="btrl" align="center">Course.</td> + <td class="btr" align="center">July.</td> + <td class="btr" align="center">August.</td> + <td class="btr" align="center">Course.</td> + <td class="btr" align="center">July.</td> + <td class="btr" align="center">August.</td></tr> +<tr><td align="center" class="btrl">North.</td> + <td class="btr" align="right">17</td> + <td class="btr" align="right">55</td> + <td align="center" class="btr">S. S. W.</td> + <td class="btr" align="right">30</td> + <td class="btr" align="right">71</td></tr> +<tr><td align="center" class="blr">N. N. E.</td> + <td class="br" align="right">64</td> + <td class="br" align="right">74</td> + <td align="center" class="br">S. W.</td> + <td class="br" align="right">33</td> + <td class="br" align="right">63</td></tr> +<tr><td align="center" class="blr">N. E.</td> + <td class="br" align="right">155</td> + <td class="br" align="right">149</td> + <td align="center" class="br">W. S. W.</td> + <td class="br" align="right">19</td> + <td class="br" align="right">43</td></tr> +<tr><td align="center" class="blr">E. N. E.</td> + <td class="br" align="right">91</td> + <td class="br" align="right">71</td> + <td align="center" class="br">West.</td> + <td class="br" align="right">12</td> + <td class="br" align="right">25</td></tr> +<tr><td align="center" class="blr">East.</td> + <td class="br" align="right">83</td> + <td class="br" align="right">60</td> + <td align="center" class="br">W. N. W.</td> + <td class="br" align="right">17</td> + <td class="br" align="right">21</td></tr> +<tr><td align="center" class="blr">E. S. E.</td> + <td class="br" align="right">25</td> + <td class="br" align="right">26</td> + <td align="center" class="br">N. W.</td> + <td class="br" align="right">13</td> + <td class="br" align="right">24</td></tr> +<tr><td align="center" class="blr">S. E.</td> + <td class="br" align="right">17</td> + <td class="br" align="right">26</td> + <td align="center" class="br">N. N. W.</td> + <td class="br" align="right">24</td> + <td class="br" align="right">56</td></tr> +<tr><td align="center" class="blr">S. S. E.</td> + <td class="br" align="right">13</td> + <td class="br" align="right">33</td> + <td align="center" class="bbr">Calm.</td> + <td class="bbr" align="right">62</td> + <td class="bbr" align="right">78</td></tr> +<tr><td align="center" class="bblr">South.</td> + <td class="bbr" align="right">9</td> + <td class="bbr" align="right">44</td> + <td class="bbr">Total</td> + <td class="bbr" align="right">684</td> + <td class="bbr" align="right">919</td></tr></table> + + +<p><span class="pagenum"><a name="Page_159" id="Page_159">[Pg 159]</a></span>Ascending to the region between 15° and 20° north latitude, and 15° to 45° +west longitude, we get north of the belt of rains <i>and lose the monsoons +entirely although still below the desert</i>; and find the regular N. E. +trades, with less variable winds than are found in almost any other part +of the ocean.</p> + +<table border="0" cellpadding="0" cellspacing="0" summary="course"> +<tr><td class="btrl" align="center">Course.</td> + <td class="btr" align="center">July.</td> + <td class="btr" align="center">August.</td> + <td class="btr" align="center">Course.</td> + <td class="btr" align="center">July.</td> + <td class="btr" align="center">August.</td></tr> +<tr><td align="center" class="btrl">North.</td> + <td class="btr" align="right">39</td> + <td class="btr" align="right">20</td> + <td align="center" class="btr">S. S. W.</td> + <td class="btr" align="right">0</td> + <td class="btr" align="right">5</td></tr> +<tr><td align="center" class="blr">N. N. E.</td> + <td class="br" align="right">210</td> + <td class="br" align="right">185</td> + <td align="center" class="br">S. W.</td> + <td class="br" align="right">0</td> + <td class="br" align="right">5</td></tr> +<tr><td align="center" class="blr">N. E.</td> + <td class="br" align="right">112</td> + <td class="br" align="right">87</td> + <td align="center" class="br">W. S. W.</td> + <td class="br" align="right">8</td> + <td class="br" align="right">3</td></tr> +<tr><td align="center" class="blr">E. N. E.</td> + <td class="br" align="right">114</td> + <td class="br" align="right">104</td> + <td align="center" class="br">West.</td> + <td class="br" align="right">0</td> + <td class="br" align="right">1</td></tr> +<tr><td align="center" class="blr">East.</td> + <td class="br" align="right">20</td> + <td class="br" align="right">36</td> + <td align="center" class="br">W. N. W.</td> + <td class="br" align="right">0</td> + <td class="br" align="right">4</td></tr> +<tr><td align="center" class="blr">E. S. E.</td> + <td class="br" align="right">21</td> + <td class="br" align="right">17</td> + <td align="center" class="br">N. W.</td> + <td class="br" align="right">3</td> + <td class="br" align="right">4</td></tr> +<tr><td align="center" class="blr">S. E.</td> + <td class="br" align="right">0</td> + <td class="br" align="right">2</td> + <td align="center" class="br">N. N. W.</td> + <td class="br" align="right">3</td> + <td class="br" align="right">31</td></tr> +<tr><td align="center" class="blr">S. S. E.</td> + <td class="br" align="right">2</td> + <td class="br" align="right">11</td> + <td align="center" class="bbr">Calm.</td> + <td class="bbr" align="right">20</td> + <td class="bbr" align="right">8</td></tr> +<tr><td align="center" class="bblr">South.</td> + <td class="bbr" align="right">5</td> + <td class="bbr" align="right">1</td> + <td class="bbr">Total</td> + <td class="bbr" align="right">557</td> + <td class="bbr" align="right">526</td></tr></table> + + +<p>Ascending still further to the region between 20° and 25° north latitude, +and 15° and 45° west longitude, which borders, in part, on the S. W. +corner of the desert, and we have not, during the month of August, a +single wind between S. S. E. and W. N. W., which blows in upon the land; +and <i>only twelve instances out of three hundred and ninety-four in this +hottest month in the year, and on the southern portion of the desert, when +the wind blows on shore from any quarter</i>. This is demonstration. The +monsoon winds are confined to the rainy belt; they do not reach the +desert, nor does the desert attract the winds from the ocean, or +reverse, hold back, or disturb the trades.</p> + +<p><span class="pagenum"><a name="Page_160" id="Page_160">[Pg 160]</a></span></p> +<table border="0" cellpadding="0" cellspacing="0" summary="course"> +<tr><td class="btrl" align="center">Course.</td> + <td class="btr" align="center">July.</td> + <td class="btr" align="center">August.</td> + <td class="btr" align="center">Course.</td> + <td class="btr" align="center">July.</td> + <td class="btr" align="center">August.</td></tr> +<tr><td align="center" class="btrl">North.</td> + <td class="btr" align="right">25</td> + <td class="btr" align="right">20</td> + <td align="center" class="btr">S. S. W.</td> + <td class="btr" align="right">3</td> + <td class="btr" align="right">0</td></tr> +<tr><td align="center" class="blr">N. N. E.</td> + <td class="br" align="right">210</td> + <td class="br" align="right">153</td> + <td align="center" class="br">S. W.</td> + <td class="br" align="right">2</td> + <td class="br" align="right">0</td></tr> +<tr><td align="center" class="blr">N. E.</td> + <td class="br" align="right">129</td> + <td class="br" align="right">77</td> + <td align="center" class="br">W. S. W.</td> + <td class="br" align="right">13</td> + <td class="br" align="right">0</td></tr> +<tr><td align="center" class="blr">E. N. E.</td> + <td class="br" align="right">110</td> + <td class="br" align="right">86</td> + <td align="center" class="br">West.</td> + <td class="br" align="right">0</td> + <td class="br" align="right">0</td></tr> +<tr><td align="center" class="blr">East.</td> + <td class="br" align="right">8</td> + <td class="br" align="right">20</td> + <td align="center" class="br">W. N. W.</td> + <td class="br" align="right">0</td> + <td class="br" align="right">3</td></tr> +<tr><td align="center" class="blr">E. S. E.</td> + <td class="br" align="right">4</td> + <td class="br" align="right">11</td> + <td align="center" class="br">N. W.</td> + <td class="br" align="right">2</td> + <td class="br" align="right">1</td></tr> +<tr><td align="center" class="blr">S. E.</td> + <td class="br" align="right">0</td> + <td class="br" align="right">3</td> + <td align="center" class="br">N. N. W.</td> + <td class="br" align="right">5</td> + <td class="br" align="right">8</td></tr> +<tr><td align="center" class="blr">S. S. E.</td> + <td class="br" align="right">1</td> + <td class="br" align="right">7</td> + <td align="center" class="bbr">Calm.</td> + <td class="bbr" align="right">2</td> + <td class="bbr" align="right">5</td></tr> +<tr><td align="center" class="bblr">South.</td> + <td class="bbr" align="right">1</td> + <td class="bbr" align="right">0</td> + <td class="bbr">Total</td> + <td class="bbr" align="right">515</td> + <td class="bbr" align="right">394</td></tr></table> + + +<p>Ascending once more, to the region between the degrees of 25 and 30, north +latitude, and 15 and 45, west longitude, we find it bounded east entirely +on the center of the desert. Now here, certainly, there must be evidence +of the truth of the rarefaction theory, if any where on the face of the +earth. Yet here, in July and August, we find the trades as regular as any +where, and not more variable winds than are found in the trades toward +their northern limits every where, and in August, only forty out of four +hundred and twenty-nine winds, blowing directly or indirectly on shore.</p> + +<table border="0" cellpadding="0" cellspacing="0" summary="course"> +<tr><td class="btrl" align="center">Course.</td> + <td class="btr" align="center">July.</td> + <td class="btr" align="center">August.</td> + <td class="btr" align="center">Course.</td> + <td class="btr" align="center">July.</td> + <td class="btr" align="center">August.</td></tr> +<tr><td align="center" class="btrl">North.</td> + <td class="btr" align="right">32</td> + <td class="btr" align="right">19</td> + <td align="center" class="btr">S. S. W.</td> + <td class="btr" align="right">9</td> + <td class="btr" align="right">6</td></tr> +<tr><td align="center" class="blr">N. N. E.</td> + <td class="br" align="right">155</td> + <td class="br" align="right">125</td> + <td align="center" class="br">S. W.</td> + <td class="br" align="right">3</td> + <td class="br" align="right">9</td></tr> +<tr><td align="center" class="blr">N. E.</td> + <td class="br" align="right">144</td> + <td class="br" align="right">35</td> + <td align="center" class="br">W. S. W.</td> + <td class="br" align="right">13</td> + <td class="br" align="right">14</td></tr> +<tr><td align="center" class="blr">E. N. E.</td> + <td class="br" align="right">140</td> + <td class="br" align="right">89</td> + <td align="center" class="br">West.</td> + <td class="br" align="right">12</td> + <td class="br" align="right">3</td></tr> +<tr><td align="center" class="blr">East.</td> + <td class="br" align="right">48</td> + <td class="br" align="right">57</td> + <td align="center" class="br">W. N. W.</td> + <td class="br" align="right">7</td> + <td class="br" align="right">7</td></tr> +<tr><td align="center" class="blr">E. S. E.</td> + <td class="br" align="right">31</td> + <td class="br" align="right">23</td> + <td align="center" class="br">N. W.</td> + <td class="br" align="right">11</td> + <td class="br" align="right">1</td></tr> +<tr><td align="center" class="blr">S. E.</td> + <td class="br" align="right">8</td> + <td class="br" align="right">7</td> + <td align="center" class="br">N. N. W.</td> + <td class="br" align="right">36</td> + <td class="br" align="right">6</td></tr> +<tr><td align="center" class="blr">S. S. E.</td> + <td class="br" align="right">8</td> + <td class="br" align="right">12</td> + <td align="center" class="bbr">Calm.</td> + <td class="bbr" align="right">18</td> + <td class="bbr" align="right">12</td></tr> +<tr><td align="center" class="bblr">South.</td> + <td class="bbr" align="right">5</td> + <td class="bbr" align="right">4</td> + <td class="bbr">Total</td> + <td class="bbr" align="right">680</td> + <td class="bbr" align="right">429</td></tr></table> + + +<p>It would seem to be impossible for any man to believe in the theory of +rarefaction, after an examination of these tables.</p> + +<p><span class="pagenum"><a name="Page_161" id="Page_161">[Pg 161]</a></span>Professor Coffin discovers other anomalies, for which he finds it +difficult to account. Among these are the northerly tendency, in the +afternoon, of the winds in Ohio, south of Lake Erie; the winds of +south-western Asia, which, he says, “Are so irregular as to defy all +attempts to reduce them to system;” particularizing the N. W. at +Jerusalem, the westerly at Bagdad, the N. E. at Constantinople, the +northerly at Trebizond, etc., etc. Jerusalem has the Mediterranean at the +N. W., Bagdad has it at the west, Constantinople has the Black Sea at the +N. E., Trebizond N. N. W. and N. E., and the counter-trade, as it passes +over them, draws its storm-surface wind or sea-breeze, from the quarter +where evaporation is greatest, and the atmosphere is most susceptible of +electrical inductive influence. Precisely as it draws from the ocean and +the eastward, east of the Alleghanies, from the lake region, west of the +lakes, and from the northward, south of the lakes, and from the westward, +east of them.</p> + +<p>This law of attraction will explain, too, the mean prevalence of easterly +winds north of the parallel of 60°, at the stations named in his work. +Great Bear Lake, Great Slave Lake, and Fort Enterprise, lie east of the +Rocky Mountain range which interposes between them and the Pacific, and +have Hudson’s Bay and other large bodies of water on the east and north. +Hence, easterly winds prevail at these places. At Norway House, on +Nelson’s River, near the north end of Lake Winnipeg, a large body of +water, which stretches off to the south, we find the south wind the<span class="pagenum"><a name="Page_162" id="Page_162">[Pg 162]</a></span> +prevalent one, especially in December, when the northern and north-eastern +waters are frozen up, and the N. E. largely present at all seasons of the +year.</p> + +<p>At New Hernhut, in winter, when Davis’ Straits are covered with floes, the +prevailing wind is east, drawn from the warm, open sea east of Greenland, +where the Gulf Stream is evaporating. But in June and July, when +evaporation is going on over Davis’ Straits and Baffin’s Bay, the +prevailing winds are west and south, and the east winds fall off.</p> + +<p>Other stations are equally instructive, but I must forbear.</p> + +<p>In relation, however, to the easterly zone of wind, of which Professor +Coffin speaks, it should be added that the counter-trade, south of the +magnetic pole, in high latitudes, pursues an easterly course, is near the +earth, and attracts an opposite wind as it does on the east and north of +the pole, in localities where the surface atmosphere is not peculiarly +susceptible to its influence, and, therefore, the <i>winds are mainly +opposite to its course</i>. Thus, at Melville Island, they are almost all +westerly and north-westerly, for there the remnant of the counter-trade is +passing west around the magnetic pole. These westerly and north-westerly +winds are very light, and like the gentle easterly breeze which sets +toward the cumulus clouds and summer showers.</p> + +<p>Since most of this work was written, I have procured, and read with great +pleasure, Lieutenant Maury’s “Geography of the Sea.” It is a work of<span class="pagenum"><a name="Page_163" id="Page_163">[Pg 163]</a></span> +great interest, and should be in the hands of every one. The extent of +ground covered, however, made it necessary for Lieutenant Maury to +introduce much matter not derived from his own investigations. In doing +this, he has taken received opinions, and has thereby introduced much +heresy. The view he adopts in relation to the monsoons, although the +popular one with philosophers, is of that character. He says (page 222):</p> + +<div class="blockquot"><p>“Monsoons are, for the most part, formed of trade-winds. When a +trade-wind is turned back, or diverted, by over-heated districts, +from its regular course at stated seasons of the year, it is regarded +as a monsoon. Thus, the African monsoons of the Atlantic, the +monsoons of the Gulf of Mexico, and the Central American monsoons of +the Pacific, are, for the most part, formed of the north-east +trade-winds, which are turned back to restore the equilibrium which +the over-heated plains of Africa, Utah, Texas, and New Mexico have +disturbed. When the monsoons prevail for five months at a time—for +it takes about a month for them to change and become settled—then +both they and the trade-winds, of which they are formed, are called +monsoons.”</p></div> + +<p>Again (§ 476-7):</p> + +<div class="blockquot"><p>“The agents which produce monsoons reside on the land. These winds +are caused by the rarefaction of the air over large districts of +country situated on the polar edge, or near the polar edge, of the +trade-winds. Thus, the monsoons of the Indian Ocean are caused by the +intense heat which the rays of a cloudless sun produce, during the +summer time, upon the Desert of Cobi and the burning plains of +Central Asia. When the sun is north of the equator, the force of his +rays, beating down upon these wide and thirsty plains, is such as to +cause the vast superincumbent body of air to expand and ascend. There +is, consequently, a rush of air, especially from toward the equator, +to restore the equilibrium; and, in this case, the force which tends +to draw the north-east trade-winds back becomes greater than the +force which is acting to propel them forward. Consequently, they obey +the stronger power, turn back, and become the famous<span class="pagenum"><a name="Page_164" id="Page_164">[Pg 164]</a></span> south-west +monsoons of the Indian Ocean, which blow from May to September +inclusive.</p> + +<p>“Of course, the vast plains of Asia are not brought up to monsoon +heat <i>per saltum</i>, or in a day. They require time both to be heated +up to this point and to be cooled down again. Hence, there is a +conflict for a few weeks about the change of the monsoon, when +neither the trade wind nor the monsoon force has fairly lost or +gained the ascendency. This debatable period amounts to about a month +at each change. So that the monsoons of the Indian Ocean prevail +really for about five months each way, viz.: from May to September, +from the south-west, in obedience to the influence of the over-heated +plains, and from November to March inclusive from the north-east, in +obedience to the trade-wind force.”</p></div> + +<p>What the “trade-wind force” is, Lieutenant Maury tells us in another +paragraph, viz.: “Calorific <ins class="correction" title="original: acion">action</ins> of the sun and diurnal rotation of the +earth”—the received calorific theory. I have already shown, I think, +conclusively, that there is no expansion and ascent in the supposed region +of calms, which induces, or can induce, the trades; and that, in point of +fact, the air on the land is cooler under the belt of rains. But as +Lieutenant Maury, whose reputation is national, adopts the theory, I shall +be pardoned for copying the following table, showing the difference of +temperature at two cities of India, before, after, and while the belt of +inter-tropical rains is over them. It will be seen that the temperature is +actually less when the belt is there, viz., in July and August, than in +April and May. <i>This should be conclusive upon that point.</i></p> + + +<p><span class="pagenum"><a name="Page_165" id="Page_165">[Pg 165]</a></span></p> +<table border="0" cellpadding="0" cellspacing="0" summary="months"> +<tr><td rowspan="2" class="btrl" align="center">Months.</td> + <td colspan="2" class="btr" align="center">Anjarakandy.</td> + <td colspan="2" class="btr" align="center">Calcutta.</td></tr> +<tr><td class="btr" align="center">Rain.</td> + <td class="btr" align="center">Temp.</td> + <td class="btr" align="center">Rain.</td> + <td class="btr" align="center">Temp.</td></tr> +<tr><td class="btrl"> </td> + <td class="btr" align="right">M.M.</td> + <td class="btr"> </td> + <td class="btr" align="right">M.M.</td> + <td class="btr"> </td></tr> +<tr><td class="blr">January,</td> + <td class="br" align="right">2,26</td> + <td class="br" align="right">26°,5</td> + <td class="br" align="right">0,0</td> + <td class="br" align="right">18°,4</td></tr> +<tr><td class="blr">February,</td> + <td class="br" align="right">2,26</td> + <td class="br" align="right">27°,7</td> + <td class="br" align="right">67,68</td> + <td class="br" align="right">21°,5</td></tr> +<tr><td class="blr">March,</td> + <td class="br" align="right">6,77</td> + <td class="br" align="right">28°,4</td> + <td class="br" align="right">24,82</td> + <td class="br" align="right">25°,6</td></tr> +<tr><td class="blr">April,</td> + <td class="br" align="right">29,33</td> + <td class="br" align="right">29°,8</td> + <td class="br" align="right">130,84</td> + <td class="br" align="right">28°,5</td></tr> +<tr><td class="blr">May,</td> + <td class="br" align="right">175,96</td> + <td class="br" align="right">28°,6</td> + <td class="br" align="right">16,24</td> + <td class="br" align="right">29°,7</td></tr> +<tr><td class="blr">June,</td> + <td class="br" align="right">794,05</td> + <td class="br" align="right">26°,6</td> + <td class="br" align="right">575,24</td> + <td class="br" align="right">29°,3</td></tr> +<tr><td class="blr">July,</td> + <td class="br" align="right">807,59</td> + <td class="br" align="right">25°,8</td> + <td class="br" align="right">338,38</td> + <td class="br" align="right">28,°1</td></tr> +<tr><td class="blr">August,</td> + <td class="br" align="right">572,98</td> + <td class="br" align="right">26°,0</td> + <td class="br" align="right">311,31</td> + <td class="br" align="right">28,°3</td></tr> +<tr><td class="blr">September,</td> + <td class="br" align="right">311,31</td> + <td class="br" align="right">26°,4</td> + <td class="br" align="right">254,91</td> + <td class="br" align="right">28,°0</td></tr> +<tr><td class="blr">October,</td> + <td class="br" align="right">157,91</td> + <td class="br" align="right">26°,8</td> + <td class="br" align="right">42,86</td> + <td class="br" align="right">27°,2</td></tr> +<tr><td class="blr">November,</td> + <td class="br" align="right">65,42</td> + <td class="br" align="right">26°,9</td> + <td class="br" align="right">20,30</td> + <td class="br" align="right">23°,0</td></tr> +<tr><td class="bblr">December,</td> + <td class="bbr" align="right">29,33</td> + <td class="bbr" align="right">26°,5</td> + <td class="bbr" align="right">0,0</td> + <td class="bbr" align="right">19°,2</td></tr> +<tr><td class="bblr" align="right">Year,</td> + <td class="bbr" align="right">2955,14</td> + <td class="bbr" align="right">27°,2</td> + <td class="bbr" align="right">1928,74</td> + <td class="bbr" align="right">26°,4</td></tr></table> + +<p>Anjarakandy is on the Malabar coast, between 12° and 13° north latitude. +Calcutta in an angle of the Bay of Bengal, at 22° 30′ north latitude. The +former is in and near the focus of the monsoons, and has a temperature in +July (when 18 inches of rain fall), about as low as in December.</p> + +<p>In the foregoing table from Kaemptz, the rain is in millimetres, about +twenty-five of which make an inch, and the temperature is centigrade, +which may be raised to Fahrenheit by adding four fifths of the quantity +and also 32°—thus, if the height of the centigrade thermometer be 25°, +add to this four fifths of 25°, which is 20°, and also 32°, the result is +77°. Twenty-five centigrade is therefore equal to seventy-seven +Fahrenheit.</p> + +<p>Lieutenant Maury is not, and should not be a theorist. He occupies the +position, in some sort, of a national <i>investigator</i>, and, of course, of +national <i>instructor</i>. Opinions which emanate from him, or<span class="pagenum"><a name="Page_166" id="Page_166">[Pg 166]</a></span> which are +endorsed by him, should be accurate. Sooner or later that which he has +adopted in relation to the monsoons, and some others, must be abandoned. +In addition to what has already been said, I wish to call his, and the +reader’s attention, to several other facts and considerations in relation +to the monsoons, and particularly those of India.</p> + +<p>1st. The deserts of Cobi and Bucharia, which constitute the “burning +plains” of <i>Central</i> Asia, north-east of the Indian Ocean, lie between 38° +and 45° of north latitude, and under the zone of extra-tropical rains. +They are not wholly rainless. They partake of that saline character which +affects so much of Asia and the western part of this continent. South of +them, running nearly east and west, are the lofty ranges of the Himmalaya +and Kuenlun Mountains, and the table lands of Thibet. To their saline +character, in part, but mainly to the interposition of these mountain +ranges, depriving the counter-trade of moisture, they owe their +comparative sterility. <i>If bountifully supplied with rains, this salt +would doubtless ere this have been washed to the ocean, as it has been +from other countries, once as salt as they.</i> But they have some rain, and +more or less vegetation, and are not intensely hot. They lie too far +north, and are too elevated. Their temperature is not materially different +from that of the western, and comparatively desert portions of our own +country, and they are utterly incapable of creating a monsoon at the +Indian Ocean, and especially from the long line of Malabar coast, where +the south-west monsoons are found in<span class="pagenum"><a name="Page_167" id="Page_167">[Pg 167]</a></span> most strength. The sterile portions +of Utah, New Mexico, and Texas are alike incapable of such effect upon the +atmosphere of Central America and Mexico. These monsoons commence in May, +and prevail until October, and the temperature of the air where they blow +ranges with considerable regularity between 76° at night, and 84° at +mid-day, on the Malabar coast, and a trifle lower in Central America.</p> + +<p class="blockquot">At Fort Fillmore, El Paso, New Mexico, in latitude 32°03, the mean temperature for</p> + +<table border="0" cellpadding="0" cellspacing="5" summary="temps"> +<tr><td>May</td><td>is</td><td class="dent">68°</td></tr> +<tr><td>June</td><td align="center">"</td><td class="dent">78°, 5′</td></tr> +<tr><td>July</td><td align="center">"</td><td class="dent">80°, 1′</td></tr> +<tr><td>August</td><td align="center">"</td><td class="dent">83°, 8′</td></tr> +<tr><td>September</td><td align="center">"</td><td class="bb">77°, 9′</td></tr> +<tr><td>And for the whole period,</td><td> </td><td class="dent">77°, 1′</td></tr></table> + +<p class="blockquot">At <ins class="correction" title="original: Stanta">Santa</ins> Fé, New Mexico, the mean for</p> + +<table border="0" cellpadding="0" cellspacing="5" summary="temps"> +<tr><td>May</td><td>is</td><td class="dent">66°, 9′</td></tr> +<tr><td>June</td><td align="center">"</td><td class="dent">72°, 5′</td></tr> +<tr><td>July</td><td align="center">"</td><td class="dent">75°, 3′</td></tr> +<tr><td><ins class="correction" title="original: Augugst">August</ins></td><td align="center">"</td><td class="dent">72°, 9′</td></tr> +<tr><td>September</td><td align="center">"</td><td class="bb">62°, 3′</td></tr> +<tr><td>And for the whole period,</td><td> </td><td class="dent">69°, 3′</td></tr> +<tr><td>Mean of the two united,</td><td> </td><td class="dent">73°, 2′</td></tr></table> + +<p>The mean of Western Texas is about 2° higher than at Fort Fillmore, and of +Utah not materially different; and the mean of <i>Central</i> Asia between 38° +and 45° does not materially vary from them.</p> + +<p>Now, it is perfectly evident that during May and September the temperature +of Central Asia is far below that of the Indian Ocean and India, and never +materially exceeds it. Central Asia is hot, “burning,” if you please, +compared with more elevated, fertile, or better watered territory <i>in the +same latitude</i>, and so it has been characterized; but not so, compared +with the Indian Ocean, or India, where the sun is vertical. During the +greater part of the time,<span class="pagenum"><a name="Page_168" id="Page_168">[Pg 168]</a></span> therefore, that the monsoons are in full blast, +Utah, Texas, and New Mexico, and Cobi, and the burning plains of Asia, are +from 5° to 10° colder than the temperature of the place where the monsoons +are blowing. Would not such a fact be perfectly conclusive in any other +science except theory-swathed meteorology?</p> + +<p>2d. The theory assumes that the heated air has an ascensive force, which +causes it to rise and create a vacuum, and this vacuum, by its suction, +draws in the adjoining air, which immediately ascends. The adjoining air, +drawn away from its locality, leaves a vacuum, and that is filled by +another rush from the S. W., and so on, till the Indian Ocean is reached, +and the monsoons are accounted for.</p> + +<p>Now, look at the difficulties:</p> + +<p>The highest temperature that can be assumed for the air over Cobi, at any +time, without disregarding facts and analogy, is 100°. What is the +ascensive power of an area of atmosphere of 100°? For this we have no +problem or formula, although problems and formulas abound in the science. +Professor Espy relied on heated air only to give the storm a <i>start</i>. His +main reliance was on the latent heat supposed to be given out during +condensation, for his ascensive storm power. But over these “burning +plains” there is, according to the theory, no storm or cloud, or +condensation on which that supposed reliance for expansion can be placed. +What, then, is the ascension force of air at 100°? <i>We ought to know, for +we sometimes have it as high, or within two<span class="pagenum"><a name="Page_169" id="Page_169">[Pg 169]</a></span> or three degrees as high, in +all the eastern and middle States.</i></p> + +<p>The monsoons blow at from twenty to twenty-five miles an hour, and +sometimes more. Is that the ascensive force of air at 100°? At 25 miles an +hour it would be 2,200 feet; at 20 miles, 1,760 feet; and at 10 miles, 880 +feet per minute.</p> + +<p>Does any man believe that either current exists? Why, then, do we not have +our hats taken off, or light objects carried up, or have a monsoon, or, at +least, have the clouds running up, when we have such elevated +temperatures. <i>Nothing of the kind occurs with us.</i> Our hottest days are +comparatively still days; and I have seen the cumulus sailing gently to +the east, horizontally, when the air was at 98°. Why should we be exempt? +Is not our air the same and our heat the same?</p> + +<p>Again, suppose we grant that the ascensive force is equal to 20 or even 10 +miles an hour, will not the adjoining air hold back somewhat to avoid +leaving behind an entire vacuum? or, will it all voluntarily rush in, and +leave a new complete vacuum? and, if so, why the preference of vacuums by +the air, and <i>when, where, and why</i>, should the <i>successive vacuums stop</i>? +Nay, would not gravity fill the second vacuum from <i>above</i>, rather than +from the south-west side? and will not the air incline to rush in, to some +or all these successive vacuums, from some other side than south-west? or, +have these deserts the power of selecting the quarter from which their +vacuum shall be filled, and of delegating it to succeeding vacuums?<span class="pagenum"><a name="Page_170" id="Page_170">[Pg 170]</a></span> Would +it not incline to rush in from the east and west where there are no +elevations, rather than from the S. W. and over the Kuenlun Mountains, the +intervening ridges and valleys of Thibet, the lofty Himmalayas, the extent +of India, and the Ghaut Mountains, from three to four thousand feet high, +on its eastern coast? Would it not, at least, <i>leak in a little</i>, and +lessen the force with which the vacuums would draw from the far-off Indian +Ocean, so that the monsoon could not blow with equal force? or, if Cobi +and its fellow deserts <i>must</i> and <i>can</i> draw from an <i>ocean</i>, why not from +the head of the Arabian Sea, or Bay of Bengal, or the China Sea, which are +nearer, or from the Japan Sea, which is still nearer, or the Yellow Sea, +which is close by? Why draw only from under the central belt of rains? +Nay, what shall be done with Professor Dove? In a recent article, +republished in the American Journal of Science and Art, for January, 1855, +he says: “A greatly diminished atmospheric pressure taking place in summer +over the <i>whole continent</i> of Asia must produce an influx from all +surrounding parts; and thus we have west winds in Europe, north winds in +the Icy Sea, east winds on the east coast of Asia, and south winds in +India. <i>The monsoon itself becomes, as we see, in this point of view, only +a secondary phenomena.</i>” This looks very like <i>antagonism</i>. Who shall we +believe?</p> + +<p>Again, suppose you get one atmosphere from the whole area, raised up by +the supposed ascensive force, and at the rate of twenty-five, twenty, or +even ten miles an hour, and a new volume drawn in from the<span class="pagenum"><a name="Page_171" id="Page_171">[Pg 171]</a></span> south-west, +and <i>over the mountains</i>: will it not take a <i>little time</i> for <i>that</i> to +<i>heat up</i>? Does it heat so fast as to <i>keep up the ascensive force</i> +without intermission, at twenty-five, or twenty, or ten miles the hour? +What says Mr. Ericsson to this? Can he not arrange with a moderate lens, +to move his engine with the rays of the summer sun? Nay, Lieutenant Maury +says they can not heat up “<i>per saltum</i>, or in a day.” But according to a +reasonable calculation, they must heat up the air from 80°, or less, to +100°, at the rate of 2,000 feet per minute. Heating 2,000 feet in depth, +in the proportion of 20° per minute, night and day, for five months, is +“<i>per saltum</i>” in a minute, and 1,440 “<i>saltums</i>” per day!</p> + +<p>And further still, the Indian Ocean, from which the monsoons are drawn to +Cobi and Central Asia to the N. E., is during those months covered by the +belt of calms and rains, as heretofore stated; and the S. E. trades +blowing into it are attributed to the suction created by the ascent of +heated air <i>there</i>. So, then, the monsoons are blowing away from under the +rainy belt, from 500 to 1000 miles, to Cobi and the burning plains of +Asia, while the ascensive force of that belt is such as to draw the S. E. +trades toward the very spot, a distance of 1,200 or 1,500 miles, at 20 +miles an hour! What must the ascensive force over Cobi, etc., be, if, as a +“stronger power,” it can overcome an ascensive force over the Indian Ocean +sufficient to draw the S. E. trades 1,500 miles, at 20 miles an hour; and, +in addition to the force necessary to resist this central suction, not +only stop or<span class="pagenum"><a name="Page_172" id="Page_172">[Pg 172]</a></span> hold back the N. E. trade, but reverse it and draw it back, +at 20 miles an hour, as a monsoon? Must it not be, at least, double that +of the belt of calms, or the “great region of expansion,” as Professor +Dove calls it?</p> + +<p>Now, I am irresistibly tempted to ask whether a meteorological theory can +be too absurd for credence, and whether it would not be as well to endow +the deserts with ribs and lungs, and a proboscis long enough to reach the +Indian Ocean, and the necessary power of inspiration and expiration? Such +a theory would avoid all difficulties, conflict with no more analogies, +and, in my judgment, be as much entitled to credit as the one to which +meteorologists adhere.</p> + +<p>3d. North of the Malabar coast, in the north-west of India, lies an +extensive desert. West of that is Beloochistan, with its rainless deserts. +Further west are the rainless deserts of Arabia, and these three, +including the Persian deserts further north, cover <i>as much surface</i> as +the deserts of Cobi and Bucharia—have the sun vertical in part, and +nearly so over the entire surface—<i>are more intensely hot</i>, and lie +within <i>one third of the distance</i> which intervenes between that desert +and the Indian Ocean off the Malabar coast, with <i>an open sea and</i> no +<i>mountains between</i>. Now, look at it. The north-west desert of India, and +the rainless deserts of Beloochistan and Arabia <i>reverse no trade</i> and +<i>have no monsoon</i>, although the Arabian Sea heads right up among them. +They do not attract one from the Indian Ocean off the Malabar coast, +although not more than one third of the <span class="pagenum"><a name="Page_173" id="Page_173">[Pg 173]</a></span>distance off, and without such +mountains and table lands intervening as separate that coast from Cobi. It +is said by Lieutenant Maury that the monsoons, “<i>obey the stronger +force</i>.” But which is the stronger force? Cobi, not <i>wholly</i> rainless, +lying north of 35°, under the zone of extra-tropical rains, with India and +the Ghauts, the Himmalaya Mountains, the table lands of Thibet, and the +Kuenlun Mountains between? or the deserts of India, Beloochistan, and +Arabia, <i>wholly rainless</i>, and <i>intensely hot, near by</i>, and in <i>open +view</i>. There can be but one answer to this question. Nothing in the way of +desert barrenness, or elevated temperature, unless it be those of Sahara, +can exceed the deserts about the head of the Arabian Sea and Persian Gulf. +Certainly those of Cobi can not compare with them; yet the trades blow +steadily over them, although more northerly there, as every where, near +their northern limits, especially on land. Says Hopkins, in his +atmospheric changes:</p> + +<div class="blockquot"><p>“If any one part of the broad expanse of the continent of Asia could +be heated so as to draw air from the Arabian Sea and the Indian Ocean +during the summer, it would be that part which lies between +Hindoostan and the Lake of Aral, including the region between the +Valley of the Oxus and Persia, and the land of this part, unlike +Hindoostan, is not screened from the sun by thick vapors. But what +says Burnes respecting the winds of this part? Why, that about the +latter end of June, though the thermometer was at 103° in the day, +‘In this country a steady wind generally blows from the north.’ And +on the 23d of August, after having passed the Oxus—‘The heat of the +sand rose to 150°, and that of the atmosphere exceeded 100°, but the +wind blew steadily, nor do I believe that it would be possible to +traverse this tract in summer if it ceased to blow. The steady manner +in which it comes from one direction is remarkable in this inland +country.’ Again—‘The air itself was not<span class="pagenum"><a name="Page_174" id="Page_174">[Pg 174]</a></span> disturbed but by the usual +north wind that blows steadily in this desert.’ And he has many other +similar passages.”</p></div> + +<p>Here there is a vast tract of country south of 35° which has a temperature +often of 103°, and does not reverse the trade and create a monsoon. How +utterly unphilosophical, then, to attribute the monsoons to Cobi because +they “obey the stronger force!” or to attribute them to it at all.</p> + +<p>4th. The monsoons can not be <i>traced from</i> the Malabar coast <i>to Cobi</i>. +They do not exist on the south-west of Cobi and near it, where they should +in greatest force, and there is no connection, in fact, shown between +them. They do not often extend more than twenty-five miles inland, or to +the east of the Ghauts. There are no corresponding intervening monsoons +crossing India to the mountains—none over the mountains and table +lands—none under the northern lee of the mountains—nor, in short, on the +whole track, nor any S. W. winds except such as naturally belong to the +action of the curving counter-trade.</p> + +<p>Finally, the investigations of Commodore Wilkes on Mauna Loa, a mountain +upon Hawaii, more than 13,000 feet high, and the observations of Professor +Wise and other aeronauts are sufficient to put this whole matter of heated +lands and ascent of the atmosphere as the cause of winds, at rest. +Commodore Wilkes was encamped for about <i>twenty days</i> on Pendulum Peak, in +December and January 1840. Although not up to the elevation of the +counter-trade<span class="pagenum"><a name="Page_175" id="Page_175">[Pg 175]</a></span> in that latitude, he was above the local clouds which form +over the island during the day, where the sea breezes blow in with as +great strength as any where. Indeed, he was on the top of the “lofty +conical mountain” to which Caleb Williams alludes in the letter to +Professor Espy I have quoted, and above the spot where Professor Espy +assumed that the clouds were rising with such force as to induce the +strong sea breezes of that island. During this time there were two +snow-storms on Mauna Loa, and they had the wind from the S. W. during the +storm, as might be expected, looking at the situation of the mountain on +the western side of the island. These storms moved to the N. W., and were +observed at the other islands in that direction as rain.</p> + +<p>The local clouds lay over the island every day, as they do over active +volcanic islands which are very elevated, although it was the dry season. +<i>Nothing like an ascent of the clouds or of the currents of air from the +ocean was observed.</i> On the contrary, the clouds formed before the sea +breezes set in, and the latter blew from the different sides of the island +in under the clouds, and outward again, probably on the opposite side. The +whole interior of the island is elevated, and its temperature low; and +<i>there was no elevation of temperature on the high portions of the island +over which the clouds formed, and toward which the winds blew, which could +create an upward current</i>.</p> + +<div class="blockquot"><p>“During our stay on the summit, we took much pleasure and interest in +watching the various movements of the clouds; this day in particular, +they attracted our attention; the whole island beneath us<span class="pagenum"><a name="Page_176" id="Page_176">[Pg 176]</a></span> was +covered with a dense white mass, in the center of which was the cloud +of the volcano rising like an immense dome. All was motionless until +the hour arrived when the sea-breeze set in from the different sides +of the island; a motion was then seen in the clouds, at the opposite +extremities, both of which seemed apparently moving toward the same +center, in undulations, until they became quite compact, and so +contracted in space as to enable us to see a well defined horizon; at +the same time there was a wind from the mountain, at right angles, +that was affecting the mass, and drawing it asunder in the opposite +direction. The play of these masses was at times in circular orbits, +as they became influenced alternately by the different forces, until +the whole was passing to and from the center in every direction, +assuming every variety of form, shape and motion.</p> + +<p>“On other days clouds would approach us from the S. W. when we had a +strong N. E. trade-wind blowing, coming up with cumulus front, +reaching the height of about eight thousand feet, spreading +horizontally, and then dissipating. At times they would be seen lying +over the island in large horizontal sheets as white as the purest +snow, with a sky above of the deepest azure blue that fancy can +depict. I saw nothing in it approaching to blackness at any time.” +(Exploring Expedition, vol iv. p. 155).</p></div> + +<p>Here, in the last paragraph, we have the whole truth disclosed. The N. E. +trade was blowing on Mauna Loa, 13,000 feet above the sea, and the +sea-breeze blew in on the <i>leeward side</i>, its moisture condensing over the +volcanic island, but without rising <i>up the mountain</i>, or <i>through the +surface-trade</i>, or <i>above 8,000 feet</i>.</p> + +<p>So, too, the celebrated aeronaut, Mr. Wise, in the course of more than a +hundred ascensions, some during high wind, and others during rain storms, +never met with an ascending current, except in a single instance, in the +body of a hail-cloud, and then there were descending currents also, the +usual intestine motion of hail-cloud with its opposite polarities.</p> + +<p>I copy a description of his passage through the<span class="pagenum"><a name="Page_177" id="Page_177">[Pg 177]</a></span> clouds of a rain-storm, +and his floating a long period above them; and there was no ascending +current which disturbed their horizontal repose or progression. The double +layer is not uncommon—condensation taking place at the connection of the +upper and lower portions of the trades, with the surrounding atmosphere; +or in the trade, and by <i>induction in the surface atmosphere</i> at the same +time. Such instances are frequently visible, and if his ascensions had +been undertaken at other times in stormy weather he would have seen more +of them.</p> + +<div class="blockquot"><p>“Before I passed the limits of the borough, a parachute, containing +an animal, was dropped, which descended fast and steady, and, just as +it reached the earth, my ærial ship entered a dense black body of +clouds. Ten minutes were consumed in penetrating this dismal ocean of +rainy vapor, occasionally meeting with great chasms, ravines, and +defiles, of different shades of light and darkness. When I emerged +from this ocean of clouds, a new and wonderfully magnificent scene +greeted my eyes. A faint sunshine shed its warmth and luster over the +surface of this vast cloud sea. The balloon rose more rapidly after +it got above it. Viewing it from an elevation above the surface, I +discovered it to present the same shape of the earth beneath, +developing mountains and valleys, corresponding to those on the +earth’s surface. The profile of the cloud-surface was more depressed +than that on the earth, and, in the distance of the cloud-valley a +magnificent sight presented itself. Pyramids and castles, rocks and +reefs, icebergs and ships, towers and domes—every thing belonging to +the grand and magnificent could be seen in this distant harbor; the +half-obscured sun shedding his mellow light upon it, gave it a rich +and dazzling luster. They were really “castles in the air,” formed of +the clouds. Casting my eyes upward, I was astonished in beholding +another cloud-stratum, far above the lower one; it was what is +commonly termed a “mackerel sky,” the sun faintly shining through it. +The balloon seemed to be stationary; the clouds above and below +appeared to be quiescent; the air castles, in the distance, stood to +their places; silence reigned supreme; it was solemnly sublime. +Solitary and alone in a mansion of the skies, my very soul swelled +with emotion; I had no companion to pour out my<span class="pagenum"><a name="Page_178" id="Page_178">[Pg 178]</a></span> feelings to. Great +God, what a scene of grandeur! Such were my thoughts; a reverence for +the works of nature, an admiration indescribable. The solemn +grandeur—the very stillness that surrounded me—seemed to make a +sound of praise.</p> + +<p>“This was a scene such that I never beheld one before or after +exactly like it. Two perfect layers of clouds, one not a mile above +the earth; the other, about a mile higher; and, between the two, a +clear atmosphere, in the midst of which the balloon stood quietly in +space. It was, indeed, a strange sight—a meteorological fact, which +we cannot possibly see or make ourselves acquainted with, without +soaring above the surface of the earth.” (History and Practice of +Aeronautics, p. 209).</p></div> + +<p>This is graphic. Perhaps in relation to the conformity of the upper +surface of the inferior layer of clouds, to the irregularities of the +earth’s surface, he was misled during the enthusiasm of the moment. He is +certainly mistaken as to the possibility of observing these double layers +from the earth; I have seen them in hundreds of instances. But in relation +to the <i>quiescence</i> of the clouds for an hour, and <i>the entire absence of +ascending currents</i>, he could not be mistaken.</p> + +<p>And now, in the absence of all direct proof to sustain the hypothesis, +that the heating of the land produces ascending currents, and thereby the +winds, and especially the monsoons, and in view of all the adverse +evidence, I put it to Lieutenant Maury, and every sincere searcher after +meteorological truth, whether the theory should not be abandoned.</p> + + +<p> </p><p> </p> +<hr style="width: 50%;" /> +<p><span class="pagenum"><a name="Page_179" id="Page_179">[Pg 179]</a></span></p> +<h2><a name="CHAPTER_VII" id="CHAPTER_VII"></a>CHAPTER VII.</h2> + +<p>The counter-trade of the northern hemisphere ranges at different heights +in different latitudes, in the same latitude at different seasons, and +also upon different days of the same season; and, like the line of +perpetual snow, has its greatest elevation in the tropics, descending +gradually to the surface of the ocean at the poles. At the northern limit +of the N. E. trades, it does not, ordinarily, approach the earth +sufficiently near for decided reciprocal action. Hence, at that point, +storms do not often originate; the winds are lighter and more variable, +and calms are more frequent than at any point, except at the meeting and +elevation of the trades, or in the polar regions. Doubtless this state of +things is increased by the feebler action of north polar magnetism, and +the irregular action of the longitudinal magnetic currents, evinced by the +irregular, and often, feeble action of the trades, near their extreme +limits. They are not unfrequently wholly wanting, near the northern limit, +for several days in succession, and calms and baffling winds are found in +their place—another effect of the irregular action of terrestrial +magnetism, consequent upon the ever-changing transit of central<span class="pagenum"><a name="Page_180" id="Page_180">[Pg 180]</a></span> activity +from south to north, and from north to south. Upon the islands, however, +and continents, which have elevated mountain peaks and ridges, especially +if of volcanic origin and activity, which approach more nearly the path of +the counter-trade, a different state of things exists. There, showers and +gusts are frequent. Thus, upon the Sandwich Island, Kauai, the most +northern one, which is within the region of the N. E. trade during ten +months of the year, and upon its volcanic peaks and elevated table-lands, +and north-easterly from them, over the district of Waioli, rain falls in +abundance during the year, while the coastlines upon other portions of the +island can not be cultivated without irrigation. (See Wilkes’ Exploring +Expedition, vol. iv. pp. 61 and 71; and American Journal of Science and +Art, for May, 1847).</p> + +<p>A like state of things, in degree, may be found upon the Canaries, and the +more elevated of the West India Islands. The Cape de Verdes are an +exception, and the Christian world are quite often called upon for +contributions of provisions, to save the inhabitants of these islands from +starvation. They lie at the northern limit of the equatorial belt, and for +a period of two months only (July and August), are supplied with rain. If, +from any cause, the belt does not move as far north as usual during any +season, unbroken drought and famine are sure to overtake them. The islands +contain some elevated peaks, and are of volcanic origin, but not of +present volcanic activity, and the counter-trades as they issue<span class="pagenum"><a name="Page_181" id="Page_181">[Pg 181]</a></span> from the +equatorial belt at their highest elevation, are too far above them for +reciprocal, influential action. If the islands could be placed 10° further +north, we should hear no more of drought or famine from them, and their +quantity of rain and fertility would be not only more permanent, but much +increased. Superadded to this, is the fact, that at that point the belt of +rains precipitates feebly because the S. E. trade originates upon the +southern part of the continent of Africa, and the N. E. mainly, upon the +desert and the Barbary States—and both are sparingly supplied with +moisture.</p> + +<p>The same state of things is strikingly obvious upon continents wherever +the mountains are sufficiently elevated, even within the trade-wind +region. Thus, in South America, the Andean ranges are of great elevation, +and spurs and table-lands extend from them a considerable distance to the +eastward. There, the S. E. and N. E. trades of the Atlantic meet in very +considerable volumes, and not only is the equatorial belt much wider than +upon the Atlantic and Pacific, but the counter-trades are met upon the +elevated peaks and mountain-ranges, and showers and storms on their +eastern slopes and summits are frequent during the dry season—down even +to the extra-tropical belt. I have already said that it was probable that +the great elevation of the Andes diverted and turned south a portion of +the N. E. counter-trade which would otherwise pass over the western coast +of Peru.</p> + +<p>The report of Lieutenant Herndon, which has come<span class="pagenum"><a name="Page_182" id="Page_182">[Pg 182]</a></span> to my notice since that +was written, states facts which strongly corroborate that opinion. It +seems that the trades and counter-trades actually <i>bank up</i>, in their +passage to the westward, against those mountains, and the true elevation +of their eastern slopes can not be barometrically ascertained. (See report +of the Exploration of the Amazon, p. 261). Lieutenant Herndon says:</p> + +<div class="blockquot"><p>“I was surprised to find the temperature of boiling water at Egas to +be but 208° 2′, the same within 2′ of a degree that it was at a point +one day’s journey below Tingo Maria, which village is several hundred +miles above the last rapids of the Huallaga river; at Santa Cruz, two +days above the mouth of the Huallaga, it was 211° 2′; at Nauta, three +hundred and five miles below this, it was 211° 3′; at Pebas, one +hundred and seventy miles below Nauta, 211° 1′. I was so much +surprised at these results that I had put the apparatus away, +thinking that its indications were valueless; but I was still more +surprised, upon making the experiment at Egas, to find that the +temperature of the boiling water had fallen 3° below what it was at +Santa Cruz, thus giving to Egas an altitude of fifteen hundred feet +above that village, which is situated more than a thousand miles up +stream of it. I continued my observations from Egas downward, and +found a regular increase in the temperature of the boiling water +until our arrival at Pará, where it was 211° 5′.</p> + +<p>“From an after-investigation, I am led to believe that the cause of +this phenomenon arises from the fact that the trade-winds are dammed +up by the Andes, and that the atmosphere in those parts is, from this +cause, compressed, and, consequently, heavier than it is further from +the mountains, though over a less elevated portion of the earth. The +discovery of this fact has led me to place little reliance in the +indications of the barometer for elevation, at the eastern foot of +the Andes. It is reasonable, however, to suppose that this cause +would no longer operate at Egas, nearly one thousand miles below the +mouth of the Huallaga.”</p></div> + +<p>The report of Lieutenant Gibbon, is also exceedingly instructive. +Separating from Lieutenant Herndon at Tarma, upon the Andes, he pursued a +southern<span class="pagenum"><a name="Page_183" id="Page_183">[Pg 183]</a></span> course, along the eastern slopes of the chain from 11° 30′ +south, almost to 18° south, at Ohuro, making a journey of about 7° 30′ of +latitude.</p> + +<p>A considerable portion of this journey was over eastern and less elevated +portions of the Andes; but little below, however, the line of perpetual +snow. Here, during the dry season, he met with frequent showers and fogs +from the eastward, but left them as he descended into the plains upon the +table-land. There he found the dry season more distinctly marked; but +occasional irregularities were found upon the table-lands, as every where +upon corresponding elevations. The S. E. trades, however, were there +obvious, during the dry season, notwithstanding the irregularities. The +rainy season, from December to May, he spent at Cochabamba, and at its +close he traveled north down the Madeira and its tributaries, to the +Amazon. Although scarcely consistent with my prescribed limits, I can not +forbear making a few extracts. Thus, when on the mountains, east of +Huanvelica, in the N. E. counter-trade, he says:</p> + +<div class="blockquot"><p>“Our course is to the eastward. The snow-capped mountains are in +sight to the west. Temperature of a spring 48°; air 44°. Lightning +flashes all around us; as the wind whirls from <i>north-east</i> to +south-west, rain and snow-flakes become hail, half the size of peas. +Thunder roars and echoes through the mountains; the mules hang their +heads, and travel slowly; the thinly-clad aboriginal walks shivering +as he drives the train ahead; the dark cumulus cloud seems to wrap +itself around us.”</p></div> + +<p>Again, at the Bombam Post-house, in the focus of change from cirrus to +cumulus, and stratus, and storm:</p> + +<div class="blockquot"><p><span class="pagenum"><a name="Page_184" id="Page_184">[Pg 184]</a></span>“The winds are very gentle, and curl the cirrus or hairy clouds in +most graceful shapes about the hoary-headed Andes, in rich and +delicate clusters; when the peak is concealed, all but the blue tinge +below the snow, we see a natural bridal vail. An <i>easterly wind</i> +lifts and turns them to dark, cumulus clouds, settled on the frosty +crown, like an old man’s winter cap; the physiognomical expression is +that of anger. The change is accompanied by thunder, and seems to +command all around to clothe themselves for storms. The cold rain +comes down in <i>fine drops</i> upon us; the day grows darker, and the +<i>clouds press close upon the earth</i>.”</p></div> + +<p>During an excursion east of Cuzco—</p> + +<div class="blockquot"><p>“Turning from the river, we ascend a steep ridge of mountains—the +eastern range at last. A heavy mist <i>wafts upward as the winds drive +it against the side of the Andes</i>, so that our view is shortened to a +few hundred yards. We hope the curtain will rise that we may view the +productions of the tropical valley below; but the mist thickens, and +the day gets dark with heavy, heaped-up black clouds; a rain-storm +follows. The grasses are thrifty, and the top of the ridge covered +with a thick sod. By barometer, we stand eleven thousand one hundred +feet above the level of the sea.”</p></div> + +<p>In May following, having spent the rainy season in Cochabamba, he travels +north—</p> + +<div class="blockquot"><p>“Our route from Tarma to Oruro was south. We traveled ahead of the +sun. In December, when we arrived in Cochabamba, the sun had just +passed us. As soon as he did so, the rains descended heavily on this +side of the ridge; it was impossible to proceed. The roads were +flooded, the ravines impassable, and the arrieros put off their +journey until the dry season had commenced. After the sun passed the +zenith of Cochabamba, and had fairly moved the rain belt after him +toward the north, then we came out from under shelter, and are now +walking behind the rain belt in dry weather, while the inhabitants +are actively employed in tending their crops.”</p></div> + +<p>So on the north of the equatorial belt, along the whole line of the Andes, +up to the northern boundary of the desert valley of the Gila, rain falls +on the high mountain-ranges, owing to the contiguity of<span class="pagenum"><a name="Page_185" id="Page_185">[Pg 185]</a></span> the counter-trade +and the diversion of showers to the north, along their eastern sides.</p> + +<p>During the survey of the boundary line between Mexico and California, +etc., by the commission under Mr. Bartlett, it became necessary to find +some spot where water and grass were abundant, for the head quarters of +the commission. This was found, and <i>could only be found</i>, upon the +Mimbres Mountains, at an old abandoned Spanish copper mine, 7,000 or 8,000 +feet above the level of the sea, surrounded with peaks of still greater +height. These elevated ranges were within influential distance of the +counter-trade, and here snow fell in the winter, from the extra-tropical +belt, and rain, in showers, in summer, at the period of the most northerly +extension of the tropical belt; when fifteen miles off, in the valley, it +was unbroken drought. Mr. Bartlett thus describes it in his Personal +Narrative:</p> + +<div class="blockquot"><p>“We reached this district on the 2d of May. Vegetation was then +forward, though there had been no rain. But it must be remembered +that during the winter there is snow, and hence a good deal of +moisture in the earth when the spring opens. The months of May and +June were moderately warm. On the third of July the first rain fell. +It then came in torrents, accompanied by hail, and lasted three or +four hours. Many of our adobe houses were deluged with water, and the +mountain-sides exhibited cataracts in every direction. The Arroyo, +which passes through the village, and which furnishes barely water +enough for our party and the animals, became so much swollen as to +render it difficult to cross; and, by the time it had received the +numerous mountain torrents, which fall into it within a mile from our +camp, it became impassable for wagons, or even mules. The dry gullies +became rapid streams, five or six feet deep, and sometimes fifty feet +or more across. On this day, a party, in coming to the copper mines, +from the plain below, <i>where there had been no rain</i>, found +themselves suddenly in a region overflowing with water,<span class="pagenum"><a name="Page_186" id="Page_186">[Pg 186]</a></span> so that +their progress was arrested, and they were obliged to wait until the +flood had subsided. After this we had occasional showers, during the +months of July and August.”</p></div> + +<p>The location of this mountain station is near the thirty-third degree of +north latitude, while the northern limit of the equatorial belt, nowhere, +except upon the mountain ranges and table-lands of Mexico, extends above +25°.</p> + +<p>There, for the reason we have been considering, it does extend further +north during July and August, in occasional showers, and in the vicinity +of Mount Picacho, Mr. Bartlett met one of its mountain thunder-storms on +the 13th of July, on his return south through Mexico, in latitude 32°, in +the following year. (Personal Narrative, vol. ii. p. 285). These showers +originated in strata of counter-trade, which had followed up along the +eastern side of the mountains and not from strata which had crossed them +and curved to the eastward, as is shown by the course of progression of +the showers.</p> + +<p>Let us look, in this connection, at a fact or two of great interest, +though not directly connected with the point in hand. The southern limit +of the extra-tropical belt in winter, on the Pacific coast of North +America, is in the vicinity of San Diego, at about 32°. In summer, that +limit is carried up above Astoria, which is in latitude 46° 11′—about +14°—yet New Mexico receives little if any rain in winter in the vicinity +of Albuquerque, but does receive a limited supply of about seven inches in +summer and autumn, five and a half inches of which falls in<span class="pagenum"><a name="Page_187" id="Page_187">[Pg 187]</a></span> June, July, +and August. Albuquerque is in latitude 35° 13′, below the southern summer +limit of the extra-tropical belt, and north of the northern limit of the +equatorial belt. This anomaly is explained by the extension west over +northern New Mexico, of the extreme western edge of our concentrated +counter-trade, by reason of its issuing further west from the equatorial +belt in its northern extension in the summer months. This western edge, in +curving to the east, north-east of New Mexico, covers the north-western +States, Iowa, Minnesota, Wisconsin, etc., and furnishes them that great +excess of summer precipitation which is a peculiarity of their climate; +and its absence further east in winter, and the very great elevation of +the Rocky Mountains and other ranges over which their ordinary +counter-trade of that season curves, account for the absence of much +precipitation and snow there, or over the valley of the Rio Grande in New +Mexico, in winter.</p> + +<p>We may now see, too, why the western coast and the Pacific region of the +continent, below 45°, are so deficient in moisture. The S. E. trades, +which arise from the western portion of the south Atlantic and the +continent of South America, which, if it were not for the Andes chain, in +their natural course, after passing the equatorial belt, would continue on +to the north-west until they passed the limits of the N. E. trades, and +curve in upon the western portion of our continent below 45°, and supply +it bountifully with rain, are, in part, perhaps, diverted along the +eastern side of those mountains to swell the volume of our counter-trade,<span class="pagenum"><a name="Page_188" id="Page_188">[Pg 188]</a></span> +and in part pass them, almost exhausted of their supply of moisture by +their contiguous reciprocal action. Hence, too, the deficiency of +precipitation at the base of the Andes, on the western side, and the +peculiar and irregular character of the winds under the western lee of the +Andean range. Baffling airs and bands of calms prevail on this portion of +the Pacific, except where the mountains fall off, and then there is a +westerly or south-westerly monsoon under the equatorial belt. Says +Lieutenant Maury in his Charts, sixth edition, p. 731:</p> + +<div class="blockquot"><p>“The passage, under canvass, from Panama to California, as at present +made, is the most tedious, uncertain, and vexatious that is known to navigators.</p> + +<p>“My investigations have been carried far enough to show that at +certain seasons of the year a vessel bound from Panama to California, +must cross at least three, at some seasons four, such meetings of +winds or bands of calms, before she can enter the region of the N. E. +trades. Hence the tedious passage.”</p></div> + +<p>Such will ever be the state of things on this continent and upon the +eastern Pacific, so long as the S. E. counter-trades are compelled to pass +over the mountain chain of South and Central America.</p> + +<p>Again, if we examine carefully the belt or zone of extra-tropical rains, +we shall find that the focus of greatest precipitation is considerably +north of its southern limit, and that, other things being equal, this +focus travels north in summer, and gives to higher latitudes their needed +summer rains. This is very apparent upon the north-western portion of our +continent, as the following table will show:</p> + + +<p><span class="pagenum"><a name="Page_189" id="Page_189">[Pg 189]</a></span></p> +<table border="0" cellpadding="0" cellspacing="0" summary="locations"> +<tr><td class="btrl"> </td> + <td class="btr" align="center">Lat.</td> + <td class="btr"><small>Jan.</small></td> + <td class="btr"><small>Feb.</small></td> + <td class="btr"><small>Mar.</small></td> + <td class="btr"><small>Apr.</small></td> + <td class="btr"><small>May.</small></td> + <td class="btr"><small>June.</small></td> + <td class="btr"><small>July.</small></td> + <td class="btr"><small>Aug.</small></td> + <td class="btr"><small>Sept.</small></td> + <td class="btr"><small>Oct.</small></td> + <td class="btr"><small>Nov.</small></td> + <td class="btr"><small>Dec.</small></td> + <td class="btr"><small>Year.</small></td></tr> +<tr><td class="blr">San Diego, Cal.</td> + <td class="btr">32° 41′</td> + <td class="btr" align="right">0.3</td> + <td class="btr" align="right">1.7</td> + <td class="btr" align="right">1.1</td> + <td class="btr" align="right">0.9</td> + <td class="btr" align="right">0.5</td> + <td class="btr" align="right">0.0</td> + <td class="btr" align="right">0.0</td> + <td class="btr" align="right">0.2</td> + <td class="btr" align="right">0.0</td> + <td class="btr" align="right">0.1</td> + <td class="btr" align="right">1.5</td> + <td class="btr" align="right">3.4</td> + <td class="btr" align="right">9.6</td></tr> +<tr><td class="blr">San Francisco.</td> + <td class="br">37° 48′</td> + <td class="br" align="right">1.7</td> + <td class="br" align="right">0.5</td> + <td class="br" align="right">4.4</td> + <td class="br" align="right">2.1</td> + <td class="br" align="right">0.4</td> + <td class="br" align="right">0.0</td> + <td class="br" align="right">0.0</td> + <td class="br" align="right">0.0</td> + <td class="br" align="right">0.4</td> + <td class="br" align="right">0.6</td> + <td class="br" align="right">3.0</td> + <td class="br" align="right">5.5</td> + <td class="br" align="right">18.8</td></tr> +<tr><td class="blr">Cant., Far W., Cal.</td> + <td class="br">39° 02′</td> + <td class="br" align="right">3.3</td> + <td class="br" align="right">0.6</td> + <td class="br" align="right">6.4</td> + <td class="br" align="right">2.2</td> + <td class="br" align="right">0.9</td> + <td class="br" align="right">0.0</td> + <td class="br" align="right">0.0</td> + <td class="br" align="right">0.0</td> + <td class="br" align="right">0.3</td> + <td class="br" align="right">0.1</td> + <td class="br" align="right">3.5</td> + <td class="br" align="right">4.6</td> + <td class="br" align="right">21.9</td></tr> +<tr><td class="blr">Astoria, Oregon.</td> + <td class="br">46° 11′</td> + <td class="br" align="right">27.0</td> + <td class="br" align="right">10.9</td> + <td class="br" align="right">6.1</td> + <td class="br" align="right">4.4</td> + <td class="br" align="right">5.9</td> + <td class="br" align="right">2.6</td> + <td class="br" align="right">0.0</td> + <td class="br" align="right">2.3</td> + <td class="br" align="right">1.9</td> + <td class="br" align="right">6.7</td> + <td class="br" align="right">13.2</td> + <td class="br" align="right">6.2</td> + <td class="br" align="right">87.2</td></tr> +<tr><td class="blr">Puget’s S’d, Ore.</td> + <td class="br">47° 07′</td> + <td class="br" align="right">11.8</td> + <td class="br" align="right">3.9</td> + <td class="br" align="right">4.7</td> + <td class="br" align="right">4.1</td> + <td class="br" align="right">0.8</td> + <td class="br" align="right">0.6</td> + <td class="br" align="right">0.5</td> + <td class="br" align="right">1.3</td> + <td class="br" align="right">1.6</td> + <td class="br" align="right">3.6</td> + <td class="br" align="right">5.9</td> + <td class="br" align="right">6.1</td> + <td class="br" align="right">44.8</td></tr> +<tr><td class="bblr">Sitka, Russ. Am.</td> + <td class="bbr">57° 3′</td> + <td class="bbr" align="right">2.5</td> + <td class="bbr" align="right">9.6</td> + <td class="bbr" align="right">3.5</td> + <td class="bbr" align="right">3.3</td> + <td class="bbr" align="right">1.9</td> + <td class="bbr" align="right">5.9</td> + <td class="bbr" align="right">3.7</td> + <td class="bbr" align="right">10.1</td> + <td class="bbr" align="right">14.8</td> + <td class="bbr" align="right">12.7</td> + <td class="bbr" align="right">7.4</td> + <td class="bbr" align="right">4.2</td> + <td class="bbr" align="right">79.5</td></tr></table> + +<p class="center">The figures are for inches and tenths of an inch of rain.</p> + +<p>Thus, it will be seen that in January, when the southern line is at San +Diego, at the south line of California, the focus of precipitation is over +Oregon; and that in August and September when the southern line is carried +up and over Oregon, the focus has traveled north to Sitka, and that it is +always at least 10° north of the southern line of the belt upon that +coast. The increased quantities of rain which fall at the focus of +precipitation there, from Oregon up, are doubtless much enhanced by the +equatorial oceanic current which flows over opposite that part of the +continent. A like effect, precisely, is produced in Europe. The quantity +of rain which falls at Bergen, in Norway, being 87<span style="font-size: 0.8em;"><sup>61</sup></span>⁄<span style="font-size: 0.6em;">100</span> inches per year, +more than three times the average for that continent.</p> + +<p>The difference shown in the foregoing table, between Astoria and Puget’s +Sound, is owing to the fact that the latter lies in the interior and +within the coast range of mountains, while Astoria is situated at the +mouth of the Columbia River, with an open view of the ocean.</p> + +<p>A like comparative increase of precipitation in<span class="pagenum"><a name="Page_190" id="Page_190">[Pg 190]</a></span> northern latitudes, in +summer, is found every where varying according to the local influences +which operate in the particular case. Thus,</p> + +<table border="0" cellpadding="0" cellspacing="0" summary="locations"> +<tr><td class="btrl">There falls in</td> + <td class="btr">Winter.</td> + <td class="btr">Spring.</td> + <td class="btr">Summer.</td> + <td class="btr">Aut’mn.</td> + <td class="btr">Year.</td></tr> +<tr><td class="btrl">Burlington, Vt., lat. 44° 20′</td> + <td class="btr">5.7</td> + <td class="btr"><span style="margin-left: .5em;">7.3</span></td> + <td class="btr">11.4</td> + <td class="btr"><span style="margin-left: .5em;">9.8</span></td> + <td class="btr">33.9</td></tr> +<tr><td class="blr">Albany, N. Y., lat. 42° 39′</td> + <td class="br">8.3</td> + <td class="br"><span style="margin-left: .5em;">9.8</span></td> + <td class="br">12.3</td> + <td class="br">10.3</td> + <td class="br">40.7</td></tr> +<tr><td class="blr">Minnesota, Iowa, lat. 41° 28′</td> + <td class="br">7.3</td> + <td class="br">12.3</td> + <td class="br">17.4</td> + <td class="br">11.7</td> + <td class="br">48.8</td></tr> +<tr><td class="blr">St. Peters’g, Russ., lat. 59° 56′</td> + <td class="br">3.89</td> + <td class="br"><span style="margin-left: .5em;">3.20</span></td> + <td class="br"><span style="margin-left: .5em;">5.70</span></td> + <td class="br"><span style="margin-left: .5em;">4.71</span></td> + <td class="br">17.51</td></tr> +<tr><td class="bblr">Pekin, China, lat. 40°</td> + <td class="bbr"><span style="margin-left: .5em;">.54</span></td> + <td class="bbr"><span style="margin-left: .5em;">3.35</span></td> + <td class="bbr">18.80</td> + <td class="bbr"><span style="margin-left: .5em;">2.29</span></td> + <td class="bbr">25.68</td></tr></table> + +<p>Pekin lies in the northern part of China, and would have a much larger +fall of rain from a concentrated counter-trade, but for the numerous +mountain-ranges which intersect its path in winter, but over which it +passes at a greater elevation during the summer—a peculiarity from which +the eastern section of this country is most remarkably and happily free.</p> + +<p>Thus, it is obvious that the focus of precipitation in the zone of extra +tropical rains, is some 8° to 12° north of its southern line, and travels +with the whole machinery in its annual transit north and south.</p> + +<p>It is a question of some difficulty, perhaps, whether this focus is +increased by the increase of magnetic action at this point, for both the +line of descent of the counter-trade, and the focus of magnetic action, +are carried up in a like manner, and for a like cause, and, in all +probability, both concur in the result.</p> + +<p>There is exceeding wisdom in this provision for the gradual subsidence of +the counter-trade, and<span class="pagenum"><a name="Page_191" id="Page_191">[Pg 191]</a></span> gradual increase of magnetic intensity, and +consequent gradual precipitation. On the European continent, and over +western Asia, there are 50° of latitude to be supplied with moisture by +this polar belt of rains. If the focus of precipitation was at its +southern border, the counter-trade would be deprived of its moisture at +that point, and little would reach the more northern portions of the globe +which are to be supplied by it. But the movement of the whole machinery +carries up the southern line from the south boundaries of the Barbary +States on to the Mediterranean and portions of southern Europe, and the +focus of precipitation and of near approach of the counter-trade to the +earth, being situated far north of the southern line, is carried up +correspondingly, while the combination of the moisture with the atmosphere +by south polar magnetism and electricity, and the gradual descent of the +counter-trade, enable it to resist, to some extent, the influence of north +polar magnetism and cold, and thus retain portions of its moisture for +distribution in the polar regions.</p> + +<p><i>The elevation of the counter-trade above the earth varies in the same +latitude with the variations in the phenomena of the weather.</i> An +attentive observation of the clouds of our climate will soon satisfy any +one of this, after he has become familiar with them, so as to distinguish +with certainty the clouds of the trade. Its range, in this country, is +from 3,000 feet, or less, to 12,000 feet above the earth, and its depth +with us probably, from 6,000 to 8,000 feet. Gay-Lussac, in his scientific +experimental balloon ascension, the first<span class="pagenum"><a name="Page_192" id="Page_192">[Pg 192]</a></span> of <i>that character</i> ever made, +except an imperfect one just previous, by himself and Biot, found it at +about 12,000 feet over Paris, and about 4,000 feet in depth. It is +detected by the thermometer when much elevated.</p> + +<p>The atmosphere grows cool as it is ascended on mountains, or by balloons. +The rate of cooling is ordinarily about 1° of Fahrenheit for every 300 +feet. If it were not for the equatorial current, this progressive decrease +of temperature would doubtless be perfectly uniform. Of Gay-Lussac’s +ascension, on this point it was said:</p> + +<div class="blockquot"><p>“At forty minutes after 9 o’clock, on the morning of the 15th +September, 1804, the scientific voyager ascended, as before, from the +garden of the repository of models. The barometer then stood at 30.66 +English inches, the thermometer at 82° Fahrenheit, and the hygrometer +at 57½°. The sky was unclouded, but misty.</p> + +<p>“During the whole of this gradual ascent, he noticed, at short +intervals, the state of the barometer, the thermometer, and the +hygrometer. Of these observations, amounting in all to twenty-one, he +has given a tabular view. We regret, however, that he has neglected +to mark the times at which they were made, since the results appear +to have been very materially modified by the progress of the day. It +would likewise have been desirable to have compared them with a +register, noted every half hour, at the Observatory. From the surface +of the earth to the height of 12,125 feet, the temperature of the +atmosphere decreased regularly, from 82° to 47° 3′ by Fahrenheit’s +scale; <i>but afterward it increased again, and reached to 53° 6′ at +the altitude of 14,000 feet</i>; evidently owing to the influence of the +warm currents of air which, as the day advanced, rose continually +from the heated ground. From that point the temperature diminished, +with only slight deviations from a perfect regularity. At the height +of 18,636 feet the thermometer subsided to 32° 9′, on the verge of +congelation; but it sunk to 14° 9′ at the enormous altitude of 22,912 +feet above Paris, or 23,040 feet above the level of the sea, the +utmost limit of the <ins class="correction" title="original: baloon's">balloon’s</ins> ascent.”</p></div> + +<p>The high range of the barometer indicated a very<span class="pagenum"><a name="Page_193" id="Page_193">[Pg 193]</a></span> considerable elevation +of the trade at the time Gay-Lussac made his ascension. I am not aware +that it has since been found at so great an elevation, in so high a +latitude, though it is undoubtedly elevated by the interposition of a +large volume of N. W. air, upon some occasions, to nearly the same +altitude with us.</p> + +<p>In the extract in relation to the ascension of Gay-Lussac, we have another +of the thousand hastily-adopted and absurd hypotheses connected with the +caloric theory. It is obviously and utterly <i>impossible</i> that in addition +to the ordinary accumulation of heat at the surface of the earth “<i>as the +day advanced</i>”—that is, <i>during the forenoon</i>, warm currents should +ascend, unobserved by Gay-Lussac during an ascent of 12,000 feet—not +<i>affecting in the least</i> so large an intervening body of the atmosphere or +his thermometer, and in such immense volumes as to increase the warmth of +a stratum of 4,000 feet in depth, an average of 3° of Fahrenheit, and to +the extent of 6° at the center.</p> + +<p>Very few balloon ascensions have been made with a view to scientific and +accurate observation. But other aeronauts have met the counter-trade at +different altitudes, and in both clear and stormy weather.</p> + +<p>Recently, in 1852, four ascensions were made in England, under the +direction of the Kew Observatory Committee, of the British Association. I +copy from the August number of the “London, Edinburg, and Dublin +Magazine,” for 1853, the following condensed amount of the result:</p> + +<div class="blockquot"><p><span class="pagenum"><a name="Page_194" id="Page_194">[Pg 194]</a></span>“The ascents took place on August 17th, August 26th, October 21st, +and November 10th, 1852, from the Vauxhall Gardens, with Mr. C. Green’s large balloon.</p> + +<p>“The principal results of the observations may be briefly stated as +follows:</p> + +<p>“Each of the four series of observations shows that the progress of +the temperature is not regular at all heights, but that at a certain +height (<i>varying on different days</i>) the regular diminution becomes +arrested, and for the space of about 2,000 feet the temperature +remains constant, or even increases by a small amount. It afterward +resumes its downward course, continuing, for the most part, to +diminish regularly throughout the remainder of the height observed. +There is thus, in the curves representing the progression of +temperature with height, an appearance of <i>dislocation</i>, always in +the same direction, but varying in amount from 7° to 12°.</p> + +<p>“In the first two series, viz.: August 17th and 26th, this peculiar +interruption of the progress of temperature is strikingly coincident +with a <i>large</i> and <i>rapid fall</i> in the temperature of the +<i>dew-point</i>. The same is exhibited in a less marked manner on +November 10th. On October 21st a dense cloud existed at a height of +about 3,000 feet; the temperature decreased uniformly from the earth +up to the <i>lower</i> surface of the cloud. When a slight rise commenced, +the rise continuing through the cloud, and to about 600 feet above +its upper surface, when the regular descending progression was +resumed. At a short distance above the cloud, the dew-point fell +considerably, but the rate of diminution of temperature does not +appear to have been affected in this instance in the same manner as +in the other series; the phenomenon so strikingly shown in the other +three cases being perhaps modified by the existence of moisture in a +<i>condensed</i> or vesicular form.</p> + +<p>“It would appear, on the whole, that about the principal plane of +condensation heat is developed in the atmosphere, which has the +effect of raising the temperature of the higher air above what it +would have been had the rate of decrease continued uniformly from the +earth upward.”</p></div> + +<p>These gentlemen do not adopt the absurd explanation of the French +philosophers; they account for the phenomenon by supposing heat to be +<i>developed</i> at that particular part of the atmosphere; but they are +equally wide of the mark. They found the excess of heat there to the +extent of 7° to 12°, and on days<span class="pagenum"><a name="Page_195" id="Page_195">[Pg 195]</a></span> when there was no condensation, or other +assignable cause for its <i>development</i>.</p> + +<p>The temperature of the counter-trade partakes, doubtless, of the +temperature of the adjoining strata at its upper and lower portion, and +has never been found much, if any, higher than 60° at the center. Nor +could it be expected. The trade, in its upward curving course, within the +tropics, attains a considerable altitude where the atmosphere is +comparatively cold, and necessarily loses a portion of its heat there, and +during its northern flow. Probably its central summer range, in the +latitude of Paris, is not far from 55°, and with us 60°.</p> + +<p>The contrast between the trade and the surrounding atmosphere, in winter, +is much more striking, and this has been observed particularly upon the +Brocken of the Alps, and in the polar regions.</p> + +<p>“In all seasons the temperature is higher on the Brocken, on a serene, +than on a cloudy day, and, in the month of January, <i>the serene days were +warmer than at Berlin</i>.” (Kämtz’s Meteorology, by Walker, p. 217.—Note.)</p> + +<p>As the portion of the counter-trade, which does not become depolarized—in +diminished volume—progresses toward the polar regions, it settles nearer +the earth, and within the Arctic circle is found but little way above it. +Thus, in December, 1821, Parry, at Winter Island, in latitude 66° 11′, +flew a kite, with a thermometer attached, to the height of 379 feet, and +found that the temperature, instead of falling 1¼°, the usual ratio of +decrease, rose ¾ of a degree.</p> + +<p><span class="pagenum"><a name="Page_196" id="Page_196">[Pg 196]</a></span>The same thing was observed at Spitzbergen, in latitude 77° 30′ north, and +at Bosekop, latitude 69° 58′, by a scientific commission, and by means of +kites, confined balloons, and the ascent of elevations.</p> + +<div class="blockquot"><p>“In winter the temperature goes on increasing with the height, up to +a certain limit, which is variable, according to the different +atmospheric circumstances, the influence of which is not yet very +exactly known. The hour of the day appears to be indifferent, since +there exists no thermometric diurnal variation in the strata of the +surface. The mean of thirty-six experiments, made with kites, or with +captive balloons, at Bosekop, latitude 69° 58′ north, has given a +mean rate of increase of 1° 6′ for the first hundred meters.<small><a name="f6.1" id="f6.1" href="#f6">[6]</a></small> +Beyond this limit, and even beyond the first 60 or 80 meters, the +temperature again becomes decreasing, at first very slowly, but +afterward the decrease is accelerated. The observations that have +been made on the flanks, or on the summits, of mountains, during the +same expeditions, entirely confirm these results. The cooling +influence of a soil, that radiates its own heat for several weeks, +without receiving any thing on the part of the sun, in compensation +of its losses, the influence of <i>counter-currents from above</i>, coming +from the west and the south-west, with a high temperature, account +for this anomaly, which, in winter, represents the normal state of +the most northern parts of the European continent.” (Walker’s Kämtz, +p. 515.—Note.)</p></div> + +<p>Mr. Walker is the only author, so far as I know, who has suspected the +true cause of the phenomenon, viz.: “currents from above coming from the +west and south-west, with a high temperature;” but the caloric theory +“sticks like a burr,” and he adheres also to the idea that a snow-clad +surface, in the absence of the sun, can aid, by radiation, in warming the +atmosphere for a distance of several hundred yards above it, increasing +the warmth as the distance from the earth increases!</p> + +<p><span class="pagenum"><a name="Page_197" id="Page_197">[Pg 197]</a></span>This contrast between the counter-trade and the adjacent atmosphere, in +winter, in latitudes as low as that of the Brocken, is probably heightened +by the increased warmth of the former, at that season. The S. E. trades +then form under a vertical sun, and the difference of temperature can not +be less than from 6° to 8°. Not unfrequently in winter and spring the rain +will fall with a temperature of 50° to 55°, when the atmosphere near the +earth is 10° or 20° or more, below those points; and it is frozen to every +object upon which it falls. The trade stratum, from which it descends, is +not warmed by “radiation” or by ascending currents from a snow-clad +surface, and during a cloudy day; nor by a “development of heat” at that +particular altitude, but it has brought its heat from the South Atlantic, +and imparts it to the rain which forms within it. There is every reason to +believe that the counter-trade flows north in a regular descending plane, +not materially differing from that of the line of perpetual snow. The +descent of the latter is well ascertained to be from about 16,000 feet at +the equator, to <i>the surface</i> at the poles. The plane of the counter-trade +is probably much the same, varying over different localities, from the +varied action between it and the earth which we are considering; and +probably both correspond with the increase of magnetic intensity.</p> + +<p>Lieutenant Maury, in an able and original article upon the circulation of +the atmosphere, conceives the bands of comparative calms at the northern +limits of the trades, which he appropriately terms<span class="pagenum"><a name="Page_198" id="Page_198">[Pg 198]</a></span> the “<i>Calms of +Cancer</i>,” to be nodes in the circulation of the atmosphere, and that the +upper or counter-trade here decends and becomes a surface wind from the S. +W., as the N. E. trade is a surface wind; and that an upper current from +the poles approaches and descends at the same node, to make the N. E. +trade. But it is evident he adopted that conclusion too hastily, as he +obviously did the conclusion that the calms of the horse latitudes were a +type of all. We have seen that the latter are increased by a diversion of +the counter-trade, and that they are avoided by making easting. So it may +be observed that our upper current is a S. W. current, and no northerly +upper current is visible, or exists over the country, however it may be in +western Europe and the North Pacific, on the west of the magnetic poles, +where cold, dry northerly and north-easterly winds are found. The origin +and progress of storms withal demonstrates that no such node can exist.</p> + +<p>Two points have been made in relation to the course of the counter-trade +in the tropics, and are relied upon to show its progress there to the N. +E., which deserve consideration.</p> + +<p>In the first place, it is well known that “rain dust” falls in +considerable quantities on the western coast of Africa, particularly about +the Cape de Verde Islands, and also upon the Mediterranean and +south-western Europe, where it is termed “sirocco dust.”</p> + +<div class="blockquot"><p>“This dust,” says Lieutenant Maury, “when subjected to microscopic +examination, is found to consist of infusoria and organisms, whose +<i>habitat</i> (place of abode) is not Africa, but South America, and<span class="pagenum"><a name="Page_199" id="Page_199">[Pg 199]</a></span> in +the S. E. trade-wind region of South America. Professor Ehrenberg has +examined specimens of sea dust, from the Cape de Verdes and the +regions thereabout, from Malta, Genoa, Lyons, and the Tyrol, and he +has found such a similarity among them as would not have been more +striking had these specimens been all taken from the same pile.</p> + +<p>“South American forms he recognizes in all of them; indeed, they are +the prevailing form in every specimen he has examined.</p> + +<p>“It may, I think, be now regarded as an established fact, that there +is a perpetual upper current of air from South America to north +Africa, and that the volume of air in these upper currents, which +flows to the northward, is nearly equal to the volume which flows to +the southward with the N. E. trade-winds, there can be no doubt,” +etc.</p></div> + +<p>Now, it is doubtless true that this dust is transported in a +counter-trade, and that such dust is found in South America, and is taken +up there by sand-spouts, like those of the ocean in form and action. Both +Humboldt and Gibbon have graphically described them. Yet I do not think +the point well taken. South-eastward of the Cape de Verdes, where the +surface-trades—which, becoming counter-trades, pass over these islands, +and, recurving, pass over the Mediterranean and south-western +Europe—should originate, there is a vast extent of unexplored continent +in the same latitude as the portion of South America where the dust is +found; and the same dry seasons, and the same spouts, in all probability, +exist in both. Until it be shown that such forms have no “<i>habitat</i>” in +central and southern and unexplored Africa, upon the same latitudes as in +South America, it may fairly be presumed that the dust is taken up there. +Indeed, the <i>curve</i> upon which this dust is found to fall, in the greatest +quantities, is very<span class="pagenum"><a name="Page_200" id="Page_200">[Pg 200]</a></span> remarkable, and corresponds remarkably with the <i>law +of curvature</i> of the counter-trade we have considered, and with the +progress of a storm upon that coast, and over the Mediterranean, +investigated by Colonel Reid. (See Reid, on Storms and Variable Winds, p. +276.) This <i>curve clearly indicates the origin of the dust in South +Africa</i>.</p> + +<p>The second point is, that ashes from the volcanos of Mexico and Central +America have fallen to the north-east of the place where they were +ejected. Mr. Redfield has grouped these instances of volcanic eruption +usually cited, and I copy from him:</p> + +<div class="blockquot"><p>“We learn from Humboldt, that in the great eruption of Jorullo, a +volcano of southern Mexico, which is 2,100 feet above the sea, in +latitude 18° 45′, longitude 161° 30′, the roofs of the houses in +Queretaro, more than 150 miles north, 37° east from the volcano, were +covered with the volcanic dust. In January, 1845, an eruption took +place in the volcano of Cosiguina, on the Pacific coast of Central +America, in latitude 13° north, and having an elevation of 3,800 +feet, the ashes from which fell on the island of Jamaica, distant 730 +miles north, 60° east from the volcano. The elevated currents by +which volcanic ashes are thus transported are seldom or never of a +transient or fortuitous character; and these results, therefore, +afford us one of the best indications of their general course. Thus, +the progress of the higher portion of the trade-wind was marked by +the eruption of Tuxtla, latitude 18° 30′, longitude 95°, which +covered the houses in Vera Cruz with ashes, at the distance of 80 +miles north, 55° west, and also at Peroté, 160 miles north, 60° west. +The ashes from the volcano, at St. Vincent, which fell at Barbadoes, +and east of that island, in 1812, mark the course of a current from +the westward, which appears there at times, in the region of clouds, +and may, perhaps, be connected with the permanent winds on the +Pacific coast of Mexico.”</p></div> + +<p>As to one of the instances cited in the foregoing paragraph, that of +Tuxtla, it may be laid out of the case—the direction conforming +substantially to the<span class="pagenum"><a name="Page_201" id="Page_201">[Pg 201]</a></span> assumed course of the counter-trade at that point. +St. Vincent lies W. N. W., or nearly so, of Barbadoes, and a N. W. or +westerly surface-wind, prior to, and during storms, is common in the West +Indies as the N. E. is here—both alike, blowing in opposition to the +progressive course of the storm. There is nothing strange or peculiar, +therefore, respecting that instance, or the existence of variable and +especially S. W. currents, between the trades, with occasional partial +condensation.</p> + +<p>The falling of the ashes from Cosiguina, upon Jamaica, has long and often +been cited, as proof that in the West Indies the prevailing upper currents +run from the S. W. But it has been ascertained that, <i>during the same +eruption, ashes fell 700 miles to the westward, on the deck of the +Conway</i>, a vessel then upon the Pacific Ocean. That case, therefore, does +not prove the absence of the S. E. counter-trade at the time, but only the +presence of another, and a different current above or below it—and it may +have been either, and transient.</p> + +<p>So of the Jorullo instance. Investigation would probably have shown that +ashes fell to the N. W., and that they were carried N. E. by a transient +S. W. wind produced by the existence of a storm to the eastward, or one of +those states of partial condensation of the counter-trade which often +produce currents at greater distances without a storm. Not one of these +cases disproves the existence of a S. E. counter-trade, and the invariable +N. W. progression of the storms of those latitudes demonstrates it.</p> + +<p><span class="pagenum"><a name="Page_202" id="Page_202">[Pg 202]</a></span>Occasional anomalous currents, depending upon storm action at considerable +distance, are found in our atmosphere, and doubtless are there also. Thus, +although the N. W. wind is almost invariably a surface wind, I have, in a +few instances, seen a N. W. set at a considerable elevation, converging +toward a peculiarly stormy state of atmosphere far south of us, about the +period of the spring equinox. And so in one or two instances I think I +have seen light cirro-stratus clouds <i>above</i> the counter-trade, when it +ran very low, setting from the N. E., although the usual and almost +invariable location of the N. E. wind is below the counter-trade and the +stratus clouds of the storm. Aeronauts, too, have found these secondary +currents beneath a serene and cloudless sky. Indeed, the S. E. +counter-trade doubtless often induces a thin secondary current of S. W. +wind between itself and the surface-trade, in the same manner that similar +currents are induced with us, and every where.</p> + +<p>A question arises here of considerable interest, which, I confess, I can +not answer to my own satisfaction. It is, whether there be, or not, <i>an +eastern progression of the body of the atmosphere above the machinery of +distribution</i>. I have thought there was, and that in set fair weather I +had seen a peculiar kind of cirro-cumulus cloud, in patches, the small +cumuli very distinct and rounded, moving due east, which indicated such a +current. But I am not satisfied, from my own observation, that it is so, +nor is it easy to determine the question. The moisture of evaporation +rarely, if ever, ascends to any considerable<span class="pagenum"><a name="Page_203" id="Page_203">[Pg 203]</a></span> elevation, and the upper +strata must be very dry. Hence, condensation, if it takes place, is thin, +and perhaps often undiscernable. Investigations upon mountains prove +little, for the winds of the inferior strata rush up their sides and over +them. It is an open question, and future observation may solve it. The +prevailing opinion seems to be that there is. If the theory of Oersted, in +relation to the circular currents of a magnet, be true, there should be +such a progression produced by opposite secondary currents, unless, +indeed, it be also true that those currents are inoperative at so great a +distance, or their influence barely suffices to retain the attenuated +atmosphere in its place. Perhaps the investigations of Ampère conflict +with it. But it is worth while, I think, for philosophers to inquire +whether the transverse position of the needle upon the wire is not the +effect of the central <i>longitudinal</i> currents, conforming to the circular +currents of the wire, and whether it is not owing to the production of the +same currents in a globe by the circular currents of Ampère, that the +globe is magnetized, and the needles made to dip.</p> + + +<p> </p><p> </p> +<hr style="width: 50%;" /> +<p><span class="pagenum"><a name="Page_204" id="Page_204">[Pg 204]</a></span></p> +<h2><a name="CHAPTER_VIII" id="CHAPTER_VIII"></a>CHAPTER VIII.</h2> + +<p>It is exceedingly desirable, in a practical point of view, to understand +the precise character of the reciprocal action which takes place between +the earth and the counter-trade, and produces the varied phenomena which +mark our climate. We have seen that the same laws, other things being +equal, operate every where, and that analogies may be sought in the +character of those phenomena elsewhere, under the same, or different, +modifying circumstances. Looking, therefore, at the magneto-electric +movable machinery as a whole, and its influence upon the atmospheric +circulation and conditions, we find many facts which point to a primary +action in the counter-trade, and others that point as significantly to a +primary local-inducing-action in the earth. Let us briefly review those to +which we have alluded, and advert to some others, and see what solution of +the question they will justify:</p> + +<p>The belt of inter-tropical rains appears to be, in width, and amount of +precipitation, and annual travel north and south, proportionate to the +volume of trades which blow into it, the quantity of moisture they +contain, and the elevation of the surface over which they meet.</p> + +<p><span class="pagenum"><a name="Page_205" id="Page_205">[Pg 205]</a></span>South America is the most thoroughly-watered country within the tropics, +except, perhaps, portions of Hindoostan, Burmah, Siam, etc., on +south-eastern Asia. The contrast between both, and Africa, as far as +explored, and as shown by its rivers, is most obvious. The Amazon, alone, +delivers more water to the ocean than all the rivers of Africa.</p> + +<p>Of the width of the belt of rains over Africa, in the interior, we know +little. Its northern extension is less, by from 7° to 10°, than the same +belt over South America, the West Indies, and Mexico. Probably its +southern is also. Upon South America, the southern edge is carried down to +Cochabamba, in latitude 18°, and probably to 25°, to the northern edge of +the coast-desert of Peru, while it is rarely, if ever, found over the +Atlantic below 7°, a difference of 12° to 20°. Over South America, too, +the quantity of water which falls is also vastly in excess of that which +falls upon the Atlantic. The main cause of these differences is obvious. +The N. E. counter-trades which blow over Africa, originate on a surface +which is rainless, as eastern Sahara, Egypt, Arabia, etc., or subject to a +dry season by the northern ascent of the southern line of the +extra-tropical belt, as the Barbary States, Syria, Persia, etc., and their +supply of moisture is necessarily scanty. On the south, the S. E. trades +originate, in part, upon the eastern portion of southern Africa, and, in +part, upon the Indian Ocean, and from the latter source, and a portion of +the Mediterranean, doubtless most of the water which falls upon Central +Africa, is derived.</p> + +<p><span class="pagenum"><a name="Page_206" id="Page_206">[Pg 206]</a></span>The N. E. and S. E. trades which blow into the inter-tropical belt upon +the eastern portion of the Atlantic, originate upon similar surfaces, and +with like effect. Thus, the S. E. trades, in summer, are from the Southern +portion of Africa, and the N. E., in part, from the Mediterranean; and, in +winter, the N. E. from the deserts, Senegambia, Nigritia, etc., and the S. +E., owing to the narrowing of the African continent, mainly from the South +Atlantic and Indian Oceans. Going west, the belt widens, and its range +increases until the Andes are reached; but under their lee, on the western +side, a totally different state of things is found, and the belt of the +coast becomes broken and irregular, as we have seen in the citation from +Maury.</p> + +<p>The width, extension, and excessive precipitation of the belt, over South +America, follow the same law. The South Atlantic widens out by the +trending of the coast to the S. W., and furnishes a large area for the +unobstructed formation and evaporative action of the S. E. trades. So the +trending of the coast to the N. W., from 5° south to the northward, opens +a large area for a like formation and action of the N. E. trades. No +correspondingly favorable circumstances exist any where, except, perhaps, +around Hindoostan, and there the fall of rain is very excessive in some +places, as on the Kassaya hills, to the extent of 400 inches per annum. In +addition to this, the magnetic line of no variation, and of greater +intensity, which runs from our magnetic pole, obliquely, S. S. E., to its +opposite and corresponding pole in<span class="pagenum"><a name="Page_207" id="Page_207">[Pg 207]</a></span> the southern hemisphere, enters the +Atlantic on the coast of North Carolina, and traverses it, and the eastern +portion of South America, through the whole trade-wind region. The +table-lands, and slopes, and high mountain peaks, meet the trades +successively, as they go west, and the latter wrench from them, to an +unusual extent, their moisture; depressing the line of perpetual snow, by +an increase of quantity on the eastern sides, several thousand feet, as it +is for a like cause depressed on the southern side of the Himmalayas. On +the eastern slopes and tops of the Andes, as we have seen, and owing to +their elevation, falls the moisture which, according to the working of the +machinery, and the law of curvature, should bless the coast line of Peru +and northern Chili, the eastern Pacific, northern Mexico, California, +Utah, and New Mexico; and, while the Andes stand, the curse of comparative +aridity must rest upon them all.</p> + +<p>Southern Chili, and western Patagonia are supplied by the N. E. trades, +which originate in the West Indies, the Gulf of Mexico, and the Caribbean +Sea, and the Pacific, off Central America, in the neighborhood of the Bay +of Panama. But there, again, the same effect of elevation is seen. The +mountain slopes of southern Chili and Patagonia are abundantly supplied, +and their mountain ranges are drenched with rain, while eastern Patagonia +and southern Buenos Ayres, under their lee, are comparatively dry. So the +S. E. trades, which originate off the western coast of South America, +curve in upon, and aided by the oceanic currents, supply, abundantly,<span class="pagenum"><a name="Page_208" id="Page_208">[Pg 208]</a></span> the +N. W. coast of this continent, north of California; and there, too, the +coast, and its elevated ranges, receive, as we have seen, a very large +proportionate supply of their moisture. Substantially, the same state of +things, as far as circumstances permit, is reproduced upon Malaysia, +Hindoostan, etc., and the interposition of arid New Holland upon the +evaporating trade-surface may be distinctly traced upon south-western +Asia. Deserts abound there; the Caspian Sea receives the drainage of a +very large surface, without an outlet; their southern line of +extra-tropical rains is carried up very far in summer, and their dry +season is intensely hot. (See an article in the American Journal of +Science, for July, 1846, by Azariah Smith.)</p> + +<p>Another fact in this connection is worthy of a moment’s consideration. The +magnetic equator, as sought by the dipping needle, is not coincident with +the geographical one. Humboldt found it, on the Andes, at 7° 1′ south, and +it has been found still lower in the Atlantic. Over Africa it rises above +the geographical equator, and descends again on the Indian Ocean. About +midway the Pacific, it becomes coincident with the equator of the earth +again. (See diagram, on page <a href="#Page_83">83</a>.) Perhaps it is not known, with certainty, +why this is so. The south pole may be situated nearer the geographical +pole than the north one—but this is not believed to be so, nor could it +make the difference. The greatest southern depression of the magnetic +equator is found where the lines of greatest intensity, and of no +variation,<span class="pagenum"><a name="Page_209" id="Page_209">[Pg 209]</a></span> are found; and at the more intense of these lines exists the +greatest depression. From this, I think, it may be inferred that the +needle is affected by the greater magnetic intensity of the northern +hemisphere, to which it may yet appear the obliquity of the earth’s axis +is owing. However this may be, or whatever the cause, no marked effect is +produced upon the trades. The S. E. trades, by reason of the greater +extent of ocean-surface on which they originate, are every where the most +extensive, regular, and forcible. The south polar waters, from which they +rise, are every where trenching upon, and overriding, the north polar +ones; and thus, by a most beneficent provision, the greater portion of the +habitable surface is placed in the northern hemisphere, and the principal +portion of the southern is left open to an extensive, active evaporative +action, which supplies the northern habitable surface with a large excess +of the needed moisture.</p> + +<p>The condensation, and consequent precipitation, which takes place at the +passing of the trades, as we have already said, over the ocean and +lowlands, takes place mainly in the day-time. Upon the table-lands and +mountain-ranges, it often continues during the evening and night. The +morning, and early part of the day, however, in tropical countries, are +generally fair at all elevations.</p> + +<p>Storms also originate in the equatorial belt, and issuing forth in great +volume and with great intensity of action, find their way up even within +the Arctic circle. Those which pass over this continent, or the<span class="pagenum"><a name="Page_210" id="Page_210">[Pg 210]</a></span> northern +Atlantic, generally originate in the West Indies, some of them over the +Caribbean Sea, some over the islands, and some over the open ocean to the +east of them; and, nearly all the most violent, during the months of +August, September, and October. It would seem most probable that the +primary action in such cases was in the trades themselves, but it is by no +means certain that such is the case. This is the class of storms of which +Mr. Redfield has industriously investigated some twenty or more; Mr. Espy +some, and Lieutenant Porter two. Their course, when very violent, is often +more directly north than that of storms, however violent, which originate +north of the calms of Cancer, owing, perhaps, to their greater +paramagnetic character. This course I have myself observed, in several +instances, about the period of the autumnal equinox—never, however, more +southerly than from S. W. to N. E., on the parallel of 41°, except in +three, and, perhaps, four, instances, when it has been S. W. by S. to N. +E. by N. I know of no class of storms in relation to which the evidence of +primary action in the counter-trade is stronger than in those of the class +which originate on the ocean east of the Windward Islands. But it is not +satisfactory as to them. Doubtless the conflict of polarities between the +passing trades is sufficient to produce the showers and rains which are +ordinarily found over the ocean and lowlands, in the equatorial belt; but +it is doubtful whether it is sufficient to produce such extensive,<span class="pagenum"><a name="Page_211" id="Page_211">[Pg 211]</a></span> +long-continued, and violent action, as that which characterizes the +hurricane autumnal gales.</p> + +<p>They occur, too, at the time when the whole machinery of distribution has +reversed its course, and is rapidly pursuing its journey south. It is a +period of great magnetic disturbance, over both land and sea; of more +active gales and local-increased precipitation. At the Magnetic +Observatory of Toronto, Canada West, these disturbances are carefully and +systematically observed, and their maxima, or periods of greatest +disturbance occur in April and September. (See Silliman’s Journal, new +series, vol. xvii. p. 145.)</p> + +<p>The tendency to volcanic action is not as great at the autumnal, as at the +vernal equinox, for the reason that most of the volcanic action of the +western hemisphere develops itself now upon South rather than North +America. But both exist, and are active, and what are improperly termed +equinoctial storms, and gales, and rains, are proverbial during, or just +subsequent to, both periods with us—as they are when the same change, +called the breaking up of the monsoons, takes place in the line of +magnetic intensity, over southern and eastern Asia. A volume might be +filled with extracts, showing, at least, most remarkable coincidences +between violent volcanic action and great atmospheric disturbance. Perhaps +the increased fall of rain at and after the equinoxes, in the northern +hemisphere, and in certain localities subject to volcanic activity, is as +strikingly illustrated by the register, kept by Mr. Johnson, on the +volcanic Island of Kauai, one of the Hawaiian group, already<span class="pagenum"><a name="Page_212" id="Page_212">[Pg 212]</a></span> alluded to, +as in any other case, although it is by no means a singular one. The +greatest fall of rain, in any month except April and October, was eight +inches. In April, the fall was fourteen inches, in October, eighteen +inches. Neither the equatorial, nor extra-tropical belt, were over the +island during those months; but they were the N. E. trades, and the result +was owing solely to the interposition of high volcanic mountains, <i>in a +state of disturbance</i>, into, or near, the strata of the counter-trade. Mr. +Dobson, in stating a theory to which we shall hereafter advert, advances +the following proposition:</p> + +<p>“7. <i>Cyclones (hurricanes) begin in the immediate neighborhood of active +volcanoes.</i> The Mauritius cyclones begin near Java; the West Indian, near +the volcanic series of the Caribbean Islands; those of the Bay of Bengal, +near the volcanic islands on its eastern shores; the typhoons of the China +Sea, near the Philippine Islands, etc.”</p> + +<p>The peculiar stormy state of the atmosphere, over the Gulf Stream, to +which I have alluded, certainly affords no evidence of primary atmospheric +action. It is a body of south polar water, pursuing its way under the +guidance of magnetism—maintaining its polarity—arched somewhat like the +roof of a house, by the outward pressure of a cold north polar current +which it has met to the east of the Banks of Newfoundland, and forced to +take an in-shore course to the southward, and the bodies of water which +the rivers discharge, and a conflict with the north polar surface-winds +which sweep over it, and fogs, and<span class="pagenum"><a name="Page_213" id="Page_213">[Pg 213]</a></span> thunder, and rain, are a matter of +course. Dr. Kane met a portion of this singular current in Baffin’s Bay, +north of 75°, which had preserved its characteristics and a considerable +proportionate excess of heat, although it probably had been around +Greenland, or found its way to the west, toward the magnetic pole, through +some of its northern fiords or straits. (Grinnel Expedition, p. 120.)</p> + +<p>The investigations of Lieutenant Maury show, that when the Gulf Stream +turns to the eastward, crossing the lines of declination at right angles, +as the counter-trades also seem to do in the same latitude, it is <i>carried +up, in summer, several degrees to the north</i>, and descends again in +winter—thus demonstrating its connection with the shifting magnetic +machinery which controls alike the ocean, the atmosphere, and the +temperature of the earth.<small><a name="f7.1" id="f7.1" href="#f7">[7]</a></small></p> + +<p>There are other irregularities which deserve to be noticed, in this +connection, although the analogical evidence they afford is far from being +decisive.</p> + +<p>I have already said that it was within my own observation, that +alternating lines of heat and cold, as well as rain and drought, existed +frequently, without regard to latitude, following, to some extent, the +course of the counter-trade. Such lines have been observed by others.</p> + +<p>Thus, Mr. Espy, after describing a snow-storm, which was followed by a +very cold N. W. wind, of several days’ continuance, says:</p> + +<div class="blockquot"><p><span class="pagenum"><a name="Page_214" id="Page_214">[Pg 214]</a></span>“This cold air covered the whole country, from Michigan to the +eastern coast of the United States, till the beginning of the great +storm of the 26th January; and, what is worthy of particular notice +is, that <i>the temperature began to increase first in the north and +north-west</i>. On the morning of the 25th, in the north-western parts +of Pennsylvania, and northern parts of New York, the <i>thermometer</i> +had already <i>risen in some places 30°</i>, and, in others, <i>above 40°</i>. +While in the S. E. corner of Pennsylvania, and in the S. E. corner of +New York it had not <i>begun to rise</i>. The <i>wind</i> also began to change +from the <i>north-west</i> to <i>south</i> and <i>south-east</i>, <i>first</i> in the +north-west parts of Pennsylvania and New York, some time before it +commenced in the south-east of those States; and, during the whole of +the 25th, the thermometer, in the north of New York, continued to +rise, though the wind was blowing from the southward, where the +thermometer was many degrees lower.”</p></div> + +<p>Thus, too, Mr. Redfield (American Journal of Science, November, 1846, p. +329):</p> + +<div class="blockquot"><p>“On the contrary, in times of the greatest depression of the +thermometer, in numerous instances, the cold period has been found to +have first taken effect in, or near, the tropical latitudes, and the +Gulf of Mexico, and has thence been propagated toward the eastern +portions of the United States, in a <ins class="correction" title="original: mannner">manner</ins> corresponding to the +observed progression of storms.”</p></div> + +<p>This was because the cold N. W. wind which <i>followed</i> storms began to +follow them as the storms curved and passed to the N. E.</p> + +<p>They occur in Europe also. Says Kämtz:</p> + +<div class="blockquot"><p>“Such contrasts are not uncommon in Europe, and, in this respect, the +Alps form a remarkable limit; for they separate the climates of the +north of Europe from the Mediterranean climates, where the +distribution of rain is not the same as in the center of Europe. +Hence the differences between the climates of the north and south of +France. <i>If the winter is mild in the north</i>, the newspapers are +filled with the lamentations of the <i>Italians</i> and <i>Provençals</i> at +the <i>severity of the cold</i>.”</p></div> + +<p>These facts seem to indicate a primary action in the counter-trade. +Probably in connection with one<span class="pagenum"><a name="Page_215" id="Page_215">[Pg 215]</a></span> class of storms they do, and with another +do not. I shall endeavor to show the distinction when I come to the +classification of storms.</p> + +<p>The difference of seasons in this country, and over the entire northern +hemisphere, is often very great. In a remarkable work of a remarkable +man—“A Brief History of Epidemic and Pestilential Diseases,” by Noah +Webster, published in 1799, 2 vols.—a history of the weather for about +two centuries—1600 to 1799 inclusive, is given generally, and then in a +tabular form. Those who think that every considerable extreme which occurs +exceeds any thing before known, will do well to consult that work. +Droughts are described, where “there was not a drop of rain for three or +four months, and cattle were fed upon the leaves of the trees.” Winters, +so intensely cold that the thermometer fell to 20° below zero, at +Brandywine; or so mild that there was little frost, and people upon +Connecticut River plowed their fields, and the <i>peach trees blossomed in +Pennsylvania in February</i>. These extremes generally existed in Europe and +America at the same time, but occasionally they were opposite and +alternate. Says Mr. Webster, in summing up the facts (vol. ii. p. 12): “It +is to be observed that in some cases a severe winter extends to both +hemispheres, sometimes to one only, and in a few cases to a part of a +hemisphere only. Thus in 1607-8, 1683-4, 1762-3, 1766-7, 1779-80, 1783-4, +the severity extended to both hemispheres. In 1640-41, 1739-40, and in +other instances, the severe winter in Europe preceded, by one year, a<span class="pagenum"><a name="Page_216" id="Page_216">[Pg 216]</a></span> +similar winter in America. In a few instances, severe frost takes place in +one hemisphere during a series of mild winters in the others; but this is +less common. In general, the severity happens in both hemispheres at once, +or in two winters, in immediate succession; and, as far as this evidence +has yet appeared, this severity is closely attendant on volcanic +discharges, with very few exceptions.”</p> + +<p>It will be seen that Dr. Webster (LL.D. and not M.D., and therefore the +remarkable character of the work) attributes great influence to +earthquakes and volcanic action. Probably he is correct in this. The +present active volcanic action of the western hemisphere is nearly all +within the trade-wind region, from Mexico to Peru inclusive. The West +India islands are of volcanic origin, and the influence of volcanic action +is not confined to a concussion of the earth, or the eruption of mud and +lava. Its connection with magnetic action, and disturbance, is +unquestionable. But whether they operate to increase or diminish the +trades, and the extent to which they induce violent electric action and +storms within and without the tropics, is a question which further +observation must determine. The ripples of the ocean, compared by +Lieutenant Banvard to that of a “boiling cauldron, or such as is formed by +water being forced from under the gate of a mill-pond,” are met with in +the vicinity of volcanic islands, where hurricanes and water-spouts +originate, and have been observed to precede storms, and be connected with +a falling barometer. But whether they are volcanic or<span class="pagenum"><a name="Page_217" id="Page_217">[Pg 217]</a></span> magneto-electric, +it is difficult to determine. Dr. Webster remarks, as the result of +observation, during the 17th century, that earthquakes had a N. W. and S. +E. progression in the United States, and especially in New England. In a +recent article, Professor Dana has examined, with great ability, the +general and remarkable trending of coast lines, groups of islands, and +ranges of mountains, from N. E. to S. W. and from N. W. to S. E. (American +Journal of Science, May, 1847.)</p> + +<p>The line of magnetic intensity, which connects our magnetic pole with its +opposite, is now upon this continent nearly a N. W. and S. E. line, and +the pole is fast traveling to the west. It may, and probably will yet, be +established, that there is an intimate connection between the cause of +volcanic action within the earth, to which the upheaval of the N. W. and +S. E., and N. E. and S. W. ranges were due, and of magnetic action +without, and between both, and the cause of <i>the S. E. extension</i> of our +summer storms and belts of showers and barometric <i>waves</i>, and the +<i>peculiar N. W. wind</i>. Our limits do not permit us to pursue the subject.</p> + +<p>Much influence upon the weather has been attributed to the spots upon the +sun. These spots are supposed to be breaks or openings in the luminous +atmosphere or photosphere of the sun, through which its dark nucleus body +is seen. Counselor Schwabe, of Dessau, has made them his study since 1826, +and has arrived at some singular results. They seem to be numerous—in +groups—and to appear periodically<span class="pagenum"><a name="Page_218" id="Page_218">[Pg 218]</a></span> with minima and maxima of ten years. +As the result of his observations, from 1826 to 1850, he gives us the +following table and remarks:</p> + +<table border="0" cellpadding="0" cellspacing="0" summary="spots"> +<tr><td class="btrl" align="center">Year.</td> + <td class="btr" align="center">Groups.</td> + <td class="btr" align="center">Days showing<br />no spots.</td> + <td class="btr" align="center">Days of<br />Observation.</td></tr> +<tr><td class="btrl">1826</td> + <td class="btr" align="center">118</td> + <td class="btr" align="center"><span style="margin-left: .5em;">22</span></td> + <td class="btr" align="center">277</td></tr> +<tr><td class="blr">1827</td> + <td class="br" align="center">161</td> + <td class="br" align="center"><span style="margin-left: 1em;">2</span></td> + <td class="br" align="center">273</td></tr> +<tr><td class="blr">1828</td> + <td class="br" align="center">225</td> + <td class="br" align="center"><span style="margin-left: 1em;">0</span></td> + <td class="br" align="center">282</td></tr> +<tr><td class="blr">1829</td> + <td class="br" align="center">199</td> + <td class="br" align="center"><span style="margin-left: 1em;">0</span></td> + <td class="br" align="center">244</td></tr> +<tr><td class="blr">1830</td> + <td class="br" align="center">190</td> + <td class="br" align="center"><span style="margin-left: 1em;">1</span></td> + <td class="br" align="center">217</td></tr> +<tr><td class="blr">1831</td> + <td class="br" align="center">149</td> + <td class="br" align="center"><span style="margin-left: 1em;">3</span></td> + <td class="br" align="center">239</td></tr> +<tr><td class="blr">1832</td> + <td class="br" align="center"><span style="margin-left: .5em;">84</span></td> + <td class="br" align="center"><span style="margin-left: .5em;">49</span></td> + <td class="br" align="center">270</td></tr> +<tr><td class="blr">1833</td> + <td class="br" align="center"><span style="margin-left: .5em;">33</span></td> + <td class="br" align="center">139</td> + <td class="br" align="center">267</td></tr> +<tr><td class="blr">1834</td> + <td class="br" align="center"><span style="margin-left: .5em;">51</span></td> + <td class="br" align="center">120</td> + <td class="br" align="center">273</td></tr> +<tr><td class="blr">1835</td> + <td class="br" align="center">173</td> + <td class="br" align="center"><span style="margin-left: .5em;">18</span></td> + <td class="br" align="center">244</td></tr> +<tr><td class="blr">1836</td> + <td class="br" align="center">272</td> + <td class="br" align="center"><span style="margin-left: 1em;">0</span></td> + <td class="br" align="center">200</td></tr> +<tr><td class="blr">1837</td> + <td class="br" align="center">333</td> + <td class="br" align="center"><span style="margin-left: 1em;">0</span></td> + <td class="br" align="center">168</td></tr> +<tr><td class="blr">1838</td> + <td class="br" align="center">282</td> + <td class="br" align="center"><span style="margin-left: 1em;">0</span></td> + <td class="br" align="center">202</td></tr> +<tr><td class="blr">1839</td> + <td class="br" align="center">162</td> + <td class="br" align="center"><span style="margin-left: 1em;">0</span></td> + <td class="br" align="center">205</td></tr> +<tr><td class="blr">1840</td> + <td class="br" align="center">152</td> + <td class="br" align="center"><span style="margin-left: 1em;">3</span></td> + <td class="br" align="center">263</td></tr> +<tr><td class="blr">1841</td> + <td class="br" align="center">102</td> + <td class="br" align="center"><span style="margin-left: .5em;">15</span></td> + <td class="br" align="center">283</td></tr> +<tr><td class="blr">1842</td> + <td class="br" align="center"><span style="margin-left: .5em;">68</span></td> + <td class="br" align="center"><span style="margin-left: .5em;">64</span></td> + <td class="br" align="center">307</td></tr> +<tr><td class="blr">1843</td> + <td class="br" align="center"><span style="margin-left: .5em;">34</span></td> + <td class="br" align="center">149</td> + <td class="br" align="center">312</td></tr> +<tr><td class="blr">1844</td> + <td class="br" align="center"><span style="margin-left: .5em;">52</span></td> + <td class="br" align="center">111</td> + <td class="br" align="center">321</td></tr> +<tr><td class="blr">1845</td> + <td class="br" align="center">114</td> + <td class="br" align="center"><span style="margin-left: .5em;">29</span></td> + <td class="br" align="center">332</td></tr> +<tr><td class="blr">1846</td> + <td class="br" align="center">157</td> + <td class="br" align="center"><span style="margin-left: 1em;">1</span></td> + <td class="br" align="center">314</td></tr> +<tr><td class="blr">1847</td> + <td class="br" align="center">257</td> + <td class="br" align="center"><span style="margin-left: 1em;">0</span></td> + <td class="br" align="center">276</td></tr> +<tr><td class="blr">1848</td> + <td class="br" align="center">330</td> + <td class="br" align="center"><span style="margin-left: 1em;">0</span></td> + <td class="br" align="center">278</td></tr> +<tr><td class="blr">1849</td> + <td class="br" align="center">238</td> + <td class="br" align="center"><span style="margin-left: 1em;">0</span></td> + <td class="br" align="center">285</td></tr> +<tr><td class="bblr">1850</td> + <td class="bbr" align="center">186</td> + <td class="bbr" align="center"><span style="margin-left: 1em;">2</span></td> + <td class="bbr" align="center">308</td></tr></table> + +<div class="blockquot"><p>“I observed large spots, visible to the naked eye, in almost all the +years not characterized by the minimum; the largest appeared in 1828, +1829, 1831, 1836, 1837, 1838, 1839, 1847, 1848. I regard all spots, +whose diameter exceeds 50”, as large, and it is only when of such a +size that they begin to be visible to even the keenest unaided sight.</p> + +<p>“The spots are, undoubtedly, closely connected with the formation of +faculæ, for I have often observed faculæ, or narben, formed at the +same points from whence the spots had disappeared, while new solar +spots were also developed within the faculæ. Every spot is surrounded +by a more or less bright, luminous cloud. I do not think that the +spots exert any influence on the annual temperature. I register the +height of the barometer and thermometer three times in the course of +each day, but the annual mean numbers deduced from their observations +have not hitherto indicated any appreciable connection between the +temperature and the number of the spots. Nor, indeed, would any +importance be due to the apparent indication of such a connection in +individual cases, unless the results were found<span class="pagenum"><a name="Page_219" id="Page_219">[Pg 219]</a></span> to correspond with +others derived from many different parts of the earth. If the solar +spots exert any slight influence on our atmosphere, my tables would, +perhaps, rather tend to show that the years which exhibit <i>a larger +number of spots</i> had a <i>smaller number of fine days</i> than those +exhibiting few spots.”</p></div> + +<p>These observations <i>seem</i> to show that the spots exert no influence upon +the weather, and to be satisfactory. But, perhaps, they are not entirely +so. No effect would, of course, be expected from day to day, and perhaps +the annual mean may not be seriously disturbed, and yet the spots may +seriously affect the seasons. Popular tradition has fixed upon certain +periods, of 10, 20, and 40 years, for the return of winters of unusual +severity; and the tables of Mr. Webster, and other facts, show that it is +not wholly without foundation. If we, and those we have cited, are not +mistaken in most of the views expressed, the natural effect of a partial +interception or failure of the sun’s rays, by or from the existence of the +spots, would be to decrease the exciting power of the solar rays upon +terrestrial magnetism, and, as a consequence, the volume of the trades and +their amount of moisture. This would increase the <i>mean</i> heat of the +summer in the temperate zone—for the <i>less</i> the volume of trade, the less +precipitation and variable wind, and succeeding polar waves of cooler air, +and the greater mean heat. On the other hand, the same cause, and the +feebler heating power of the sun’s rays, would make the winters more +severe, both from an absence of a portion of heat, derived directly from +the sun’s rays, and a less mitigating influence, from the action of the +trade, by reason of its decreased volume. So, too, the absence of spots, +and a more powerful influence<span class="pagenum"><a name="Page_220" id="Page_220">[Pg 220]</a></span> from the solar rays, may gradually carry +the machinery further north in summer, and further south in winter, and +thus make the <i>seasons extreme</i> without seriously disturbing the mean of +the year. And both these may occur in a more marked degree over our +intense magnetic area than in Europe. I am satisfied that they do so +occur. That the partial failure of the sun’s rays limits the transit of +the machinery, and the volume of the trades during the latter half of the +decade, and extends the transit and increases the volume during the first +half, producing an occasional severe summer drought and severe winter, in +the warmest portion of the decade. And that the variations correspond with +the difference in the character and number of the spots in different +decades, and hence the longer and shorter periods.</p> + +<p>Turning to the tables of Dr. Webster, we find that a general tendency to +extreme seasons does seem to exist from the 6th to the 10th year of every +decade, and especially of every alternate decade. The periods of 1707-8, +1728, 1737 and 1739, 1749-50, 1758-9, 1779-80, 1798-9, are those in which +the tendency was seen most decided. These tables are very general. The +thermometer was not perfected till about 1700, and did not get into +general use before 1750. There were very few meteorological registers +kept, or accessible to Dr. Webster. Hence he was obliged to resort to such +other sources of information as were open to him, and such statements as +he found are not always entirely reliable. The oldest inhabitant is apt to +express himself very strongly respecting present extremes, and fail +<span class="pagenum"><a name="Page_221" id="Page_221">[Pg 221]</a></span>somewhat in his recollection of those which have past. Still his tables +afford general and obvious evidence of the regularity of those periodic +conditions.</p> + + +<table border="0" cellpadding="0" cellspacing="0" summary="hotdry"> +<tr><td class="btrl">A.D.</td><td class="btr">Summer.</td><td class="btr">Winter.</td></tr> +<tr><td class="btrl">1701</td><td class="btr">hot and dry</td><td class="btr">....</td></tr> +<tr><td class="blr">1702</td><td class="br">hot and dry</td><td class="br">....</td></tr> +<tr><td class="blr">1703</td><td class="br">....</td><td class="br">....</td></tr> +<tr><td class="blr">1704</td><td class="br">dry Europe</td><td class="br">....</td></tr> +<tr><td class="blr">1705</td><td class="br">....</td><td class="br">....</td></tr> +<tr><td class="blr">1706</td><td class="br">hot, dry Europe</td><td class="br">....</td></tr> +<tr><td class="blr">1707</td><td class="br">very hot</td><td class="br">....</td></tr> +<tr><td class="blr">1708</td><td class="br">....</td><td class="br">very severe</td></tr> +<tr><td class="blr">1709</td><td class="br">....</td><td class="br">....</td></tr> +<tr><td class="blr">1710</td><td class="br">....</td><td class="br">....</td></tr> +<tr><td class="blr">1711</td><td class="br">....</td><td class="br">cold Europe</td></tr> +<tr><td class="blr">1712</td><td class="br">wet England</td><td class="br">....</td></tr> +<tr><td class="blr">1713</td><td class="br">wet England</td><td class="br">mild</td></tr> +<tr><td class="blr">1714</td><td class="br">dry and hot</td><td class="br">....</td></tr> +<tr><td class="blr">1715</td><td class="br">dry</td><td class="br">....</td></tr> +<tr><td class="blr">1716</td><td class="br">very dry</td><td class="br">severe</td></tr> +<tr><td class="blr">1717</td><td class="br">....</td><td class="br">severe</td></tr> +<tr><td class="blr">1718</td><td class="br">hot and wet</td><td class="br">....</td></tr> +<tr><td class="blr">1719</td><td class="br">....</td><td class="br">cold America</td></tr> +<tr><td class="blr">1720</td><td class="br">dry Europe</td><td class="br">....</td></tr> +<tr><td class="blr">1721</td><td class="br">....</td><td class="br">....</td></tr> +<tr><td class="blr">1722</td><td class="br">cold, wet</td><td class="br">....</td></tr> +<tr><td class="blr">1723</td><td class="br">....</td><td class="br">cold</td></tr> +<tr><td class="blr">1724</td><td class="br">wet England</td><td class="br">....</td></tr> +<tr><td class="blr">1725</td><td class="br">wet England</td><td class="br">....</td></tr> +<tr><td class="blr">1726</td><td class="br">....</td><td class="br">....</td></tr> +<tr><td class="blr">1727</td><td class="br">dry, hot Amer.</td><td class="br">....</td></tr> +<tr><td class="blr">1728</td><td class="br">hot Amer.</td><td class="br">severe Europe</td></tr> +<tr><td class="blr">1729</td><td class="br">....</td><td class="br">....</td></tr> +<tr><td class="blr">1730</td><td class="br">....</td><td class="br">very cold Eng.</td></tr> +<tr><td class="blr">1731</td><td class="br">....</td><td class="br">....</td></tr> +<tr><td class="blr">1732</td><td class="br">....</td><td class="br">severe Amer.</td></tr> +<tr><td class="blr">1733</td><td class="br">dry Eng.</td><td class="br">....</td></tr> +<tr><td class="blr">1734</td><td class="br">....</td><td class="br">....</td></tr> +<tr><td class="blr">1735</td><td class="br">wet</td><td class="br">....</td></tr> +<tr><td class="blr">1736</td><td class="br">wet</td><td class="br">....</td></tr> +<tr><td class="blr">1737</td><td class="br">....</td><td class="br">very severe Am.</td></tr> +<tr><td class="blr">1738</td><td class="br">....</td><td class="br">....</td></tr> +<tr><td class="blr">1739</td><td class="br">wet England</td><td class="br">very severe Eng.</td></tr> +<tr><td class="blr">1740</td><td class="br">....</td><td class="br">very severe Am.</td></tr> +<tr><td class="blr">1741</td><td class="br">....</td><td class="br">....</td></tr> +<tr><td class="blr">1742</td><td class="br">....</td><td class="br">severe Syria</td></tr> +<tr><td class="blr">1743</td><td class="br">hot</td><td class="br">....</td></tr> +<tr><td class="blr">1744</td><td class="br">....</td><td class="br">....</td></tr> +<tr><td class="blr">1745</td><td class="br">....</td><td class="br">....</td></tr> +<tr><td class="blr">1746</td><td class="br">....</td><td class="br">....</td></tr> +<tr><td class="blr">1747</td><td class="br">hot and dry</td><td class="br">severe</td></tr> +<tr><td class="blr">1748</td><td class="br">dry</td><td class="br">....</td></tr> +<tr><td class="blr">1749</td><td class="br">very dry</td><td class="br">....</td></tr> +<tr><td class="blr">1750</td><td class="br">very hot</td><td class="br">very severe</td></tr> +<tr><td class="blr">1751</td><td class="br">wet England</td><td class="br">severe Amer.</td></tr> +<tr><td class="blr">1752</td><td class="br">very hot Amer.</td><td class="br">....</td></tr> +<tr><td class="blr">1753</td><td class="br">....</td><td class="br">severe</td></tr> +<tr><td class="blr">1754</td><td class="br">....</td><td class="br">mild Amer.</td></tr> +<tr><td class="blr">1755</td><td class="br">....</td><td class="br">severe Europe</td></tr> +<tr><td class="blr">1756</td><td class="br">....</td><td class="br">severe Syria</td></tr> +<tr><td class="blr">1757</td><td class="br">....</td><td class="br">....</td></tr> +<tr><td class="blr">1758</td><td class="br">hot</td><td class="br">....</td></tr> +<tr><td class="blr">1759</td><td class="br">....</td><td class="br">severe</td></tr> +<tr><td class="blr">1760</td><td class="br">....</td><td class="br">....</td></tr> +<tr><td class="blr">1761</td><td class="br">very dry Amer.</td><td class="br">....</td></tr> +<tr><td class="blr">1762</td><td class="br">very dry Amer.</td><td class="br">severe</td></tr> +<tr><td class="blr">1763</td><td class="br">....</td><td class="br">....</td></tr> +<tr><td class="blr">1764</td><td class="br">hot Europe</td><td class="br">....</td></tr> +<tr><td class="blr">1765</td><td class="br">hot Europe</td><td class="br">severe Europe</td></tr> +<tr><td class="blr">1766</td><td class="br">hot and dry Eur.</td><td class="br">very severe</td></tr> +<tr><td class="blr">1767</td><td class="br">....</td><td class="br">cold</td></tr> +<tr><td class="blr">1768</td><td class="br">hot</td><td class="br">....</td></tr> +<tr><td class="blr">1769</td><td class="br">hot</td><td class="br">....</td></tr> +<tr><td class="blr">1770</td><td class="br">wet England</td><td class="br">....</td></tr> +<tr><td class="blr">1771</td><td class="br">wet Am. & England</td><td class="br">cold Europe</td></tr> +<tr><td class="blr">1772</td><td class="br">hot America</td><td class="br">Am., great snow</td></tr> +<tr><td class="blr">1773</td><td class="br">....</td><td class="br">....</td></tr> +<tr><td class="blr">1774</td><td class="br">....</td><td class="br">severe Europe</td></tr> +<tr><td class="blr">1775</td><td class="br">....</td><td class="br">....</td></tr> +<tr><td class="blr">1776</td><td class="br">hot</td><td class="br">severe Europe</td></tr> +<tr><td class="blr">1777</td><td class="br">....</td><td class="br">....</td></tr> +<tr><td class="blr">1778</td><td class="br">hot</td><td class="br">mild</td></tr> +<tr><td class="blr">1779</td><td class="br">hot Eng.</td><td class="br">very severe</td></tr> +<tr><td class="blr">1780</td><td class="br">....</td><td class="br">....</td></tr> +<tr><td class="blr">1781</td><td class="br">....</td><td class="br">....</td></tr> +<tr><td class="blr">1782</td><td class="br">dry Amer.</td><td class="br">....</td></tr> +<tr><td class="blr">1783</td><td class="br">hot</td><td class="br">very severe</td></tr> +<tr><td class="blr">1784</td><td class="br">hot</td><td class="br">....</td></tr> +<tr><td class="blr">1785</td><td class="br">dry Europe</td><td class="br">cold</td></tr> +<tr><td class="blr">1786</td><td class="br">cool</td><td class="br">cold</td></tr> +<tr><td class="blr">1787</td><td class="br">cool</td><td class="br">....</td></tr> +<tr><td class="blr">1788</td><td class="br">rainy Amer.</td><td class="br">cold</td></tr> +<tr><td class="blr">1789</td><td class="br">cool spring, hot summer</td><td class="br">severe Eur., mild Amer.</td></tr> +<tr><td class="blr">1790</td><td class="br">....</td><td class="br">....</td></tr> +<tr><td class="blr">1791</td><td class="br">very hot Am.</td><td class="br">cold</td></tr> +<tr><td class="blr">1792</td><td class="br">....</td><td class="br">....</td></tr> +<tr><td class="blr">1793</td><td class="br">hot, dry Am.</td><td class="br">mild Amer.</td></tr> +<tr><td class="blr">1794</td><td class="br">....</td><td class="br">severe Europe</td></tr> +<tr><td class="blr">1795</td><td class="br">Amer., hot, rainy</td><td class="br">....</td></tr> +<tr><td class="blr">1796</td><td class="br">Autumn very Dry Am.</td><td class="br">cold Amer.</td></tr> +<tr><td class="blr">1797</td><td class="br">cool Am.</td><td class="br">severe Amer.</td></tr> +<tr><td class="blr"><ins class="correction" title="original: 1198">1798</ins></td> + <td class="br">very hot<span style="margin-left: 2em;">}</span></td><td class="br">{long & severe</td></tr> +<tr><td class="bblr">1799</td><td class="bbr">very dry Am.}</td><td class="bbr">{Amer. & Eur.</td></tr></table> + +<p>Still more definite evidence is found in the meteorological tables of Dr. +Holyoke and Dr. Hildreth, and<span class="pagenum"><a name="Page_222" id="Page_222">[Pg 222]</a></span> an account, by Dr. Hildreth, of the seasons +when the Ohio River was closed or obstructed by ice, found in Silliman’s +Journal, new series, vol. xiii. p. 238.</p> + +<p>Thus, we have, from the tables of Dr. Holyoke, the following annual means, +from 1786 to 1825, inclusive. I have arranged them in periods of five +years. It will be seen that there are three peculiarities observable. +First, a marked difference between the first and second periods of the +decade, corresponding, generally, with the presence or absence of the +spots. Second, a difference in the mean of the decades which may well be +supposed to correspond with the difference in the number or size of the +spots since a like difference is observable in number and size, and the +time when they reached their maxima and minima, in the table of Schwabe. +And, third, there are occasional single cold years during the warm period, +and these correspond with what the tables of Dr. Webster show for both the +sixteenth and seventeenth centuries. In relation to this, it should be +remembered that volcanic action is a frequent and powerful disturber of +the regular action of terrestrial magnetism, and that the extremes, for +that reason, are frequently meridional or local and alternating; and to +that cause very great extremes, and marked exceptions, may be due, +notwithstanding the spots upon the sun may exert an influence in producing +hot summers and cold winters toward the close of each decade. Thus, to +select an instance to illustrate this and explain an anomaly: The coldest +season during the whole period, embraced in the following tables, is that +of 1812. This occurs during the decrease of<span class="pagenum"><a name="Page_223" id="Page_223">[Pg 223]</a></span> spots, and the warm half of +the decade. Turning to the table of volcanic action, and of earthquakes, +found in the Report of the British Association for 1854, we find that year +was remarkable for earthquakes in the United States and South America. In +December, 1811, earthquakes commenced in the valley of the Mississippi, +Ohio, and Arkansas, felt also at places in Tennessee, Kentucky, Missouri, +Indiana, Virginia, North and South Carolina, Georgia, and Florida, though +not so severely east of the Alleghanies, <i>which continued until 1813</i>. +About the same time they commenced in Caraccas, and, in March, 1812, +became severe over the greater portion of the northern section of South +America, and in the Atlantic. No such general and continued succession of +earthquakes occurred during the other periods embraced in the tables, and +the mean of the following five years was very low, embracing the memorable +cold summer of 1816.</p> + +<table border="0" cellpadding="0" cellspacing="0" summary="coldwarm"> +<tr><td class="btrl" align="center">Cold Period.</td> + <td class="btr" align="center">Warm Period.</td> + <td class="btr" align="center">Cold Period.</td> + <td class="btr" align="center">Warm Period.</td></tr> +<tr><td class="btrl">1786<span class="spacer3"> </span>48°.53</td> + <td class="btr">1791<span class="spacer2"> </span>48°.963</td> + <td class="btr">1796<span class="spacer2"> </span>48°.678</td> + <td class="btr">1801<span class="spacer2"> </span>50°.432</td></tr> +<tr><td class="blr">1787<span class="spacer3"> </span>47°.88</td> + <td class="br">1792<span class="spacer2"> </span>48°.44</td> + <td class="br">1797<span class="spacer2"> </span>48°.135</td> + <td class="br">1802<span class="spacer2"> </span>50°.794</td></tr> +<tr><td class="blr">1788<span class="spacer3"> </span>47°.676</td> + <td class="br">1793<span class="spacer2"> </span>50°.96</td> + <td class="br">1798<span class="spacer2"> </span>49°.471</td> + <td class="br">1803<span class="spacer2"> </span>50°.24</td></tr> +<tr><td class="blr">1789<span class="spacer3"> </span>47°.68</td> + <td class="br">1794<span class="spacer2"> </span>50°.768</td> + <td class="br">1799<span class="spacer2"> </span>48°.291</td> + <td class="br">1804<span class="spacer2"> </span>48°.328</td></tr> +<tr><td class="blr">1790<span class="spacer3"> </span>46°.53</td> + <td class="br">1795<span class="spacer2"> </span>50°.173</td> + <td class="br">1800<span class="spacer2"> </span>49°.989</td> + <td class="br">1805<span class="spacer2"> </span>50°.792</td></tr> +<tr><td class="btrl">Mean of period 47°.659</td> + <td class="btr">Mean<span class="spacer2"> </span>49°.901</td> + <td class="btr">Mean<span class="spacer2"> </span>48°.910</td> + <td class="btr">Mean<span class="spacer2"> </span>50°.117</td></tr> +<tr><td class="blr"> </td><td class="br"> </td><td class="br"> </td><td class="br"> </td></tr> +<tr><td class="btrl">1806<span class="spacer3"> </span>47°.982</td> + <td class="btr">1811<span class="spacer2"> </span>50°.76</td> + <td class="btr">1816<span class="spacer2"> </span>47°.113</td> + <td class="btr">1821<span class="spacer2"> </span>48°.15</td></tr> +<tr><td class="blr">1807<span class="spacer3"> </span>48°.132</td> + <td class="br">1812<span class="spacer2"> </span>45°.28</td> + <td class="br">1817<span class="spacer2"> </span>46°.277</td> + <td class="br">1822<span class="spacer2"> </span>49°.81</td></tr> +<tr><td class="blr">1808<span class="spacer3"> </span>49°.485</td> + <td class="br">1813<span class="spacer2"> </span>47°.702</td> + <td class="br">1818<span class="spacer2"> </span>48°.009</td> + <td class="br">1823<span class="spacer2"> </span>47°.58</td></tr> +<tr><td class="blr">1809<span class="spacer3"> </span>47°.92</td> + <td class="br">1814<span class="spacer2"> </span>48°.279</td> + <td class="br">1819<span class="spacer2"> </span>50°.75</td> + <td class="br">1824<span class="spacer2"> </span>49°.25</td></tr> +<tr><td class="bblr">1810<span class="spacer3"> </span>49°.001</td> + <td class="bbr">1815<span class="spacer2"> </span>47°.607</td> + <td class="bbr">1820<span class="spacer2"> </span>48°.70</td> + <td class="bbr">1825<span class="spacer2"> </span>50°.99</td></tr> +<tr><td class="bblr">Mean<span class="spacer3"> </span>48°.505</td> + <td class="bbr">Mean<span class="spacer2"> </span>47°.925</td> + <td class="bbr">Mean<span class="spacer2"> </span>48°.169</td> + <td class="bbr">Mean<span class="spacer2"> </span>49°.15</td></tr></table> + +<p>The tables of Dr. Hildreth, from 1826 to 1854, inclusive, furnish, +generally, evidence of a like character. There are, however, an anomaly or +two which<span class="pagenum"><a name="Page_224" id="Page_224">[Pg 224]</a></span> will be observed. From 1826 to 1830, the mean is high during +the period when spots were at a maximum. But that maximum embraced a much +less number of spots than the two succeeding ones. A contrast appears in +the tables of Dr. Hildreth, during the early period, for Dr. Holyoke’s +register, for 1827, puts it <i>below the mean</i>, but Dr. Hildreth’s one of +the <i>highest of the half century</i>. In 1835 commenced a period when the +spots were much more numerous, and from 1835 to 1838, inclusive, the +seasons were correspondingly below the mean. From that period to 1844 a +gradual and slightly irregular rise took place, excepting the year 1843, +when another cold year intervened. The table of earthquakes, published by +the British Association, closes with 1842, and I have not access to any +others. The occurrence of such cold years, in the warm period, at +intervals during the two centuries previous, and in 1812, and onward, and +evidently owing to increased volcanic action beneath the western portion +of the northern hemisphere, justifies the belief that the low temperature +of 1843 was owing to the same cause. The following are the means from the +tables of Dr. Hildreth:</p> + +<table border="0" cellpadding="0" cellspacing="0" summary="hildreth"> +<tr><td class="btrl">1826<span class="spacer2"> </span>54°.00</td> + <td class="btr">1831<span class="spacer2"> </span>50°.87</td> + <td class="btr">1836<span class="spacer2"> </span>50°.03</td> + <td class="btr">1841<span class="spacer2"> </span> 52°.18</td> + <td class="btr">1846<span class="spacer2"> </span>53°.64</td></tr> +<tr><td class="blr">1827<span class="spacer2"> </span>54°.92</td> + <td class="br">1832<span class="spacer2"> </span>52°.42</td> + <td class="br">1837<span class="spacer2"> </span>51°.57</td> + <td class="br">1842<span class="spacer2"> </span>52°.83</td> + <td class="br">1847<span class="spacer2"> </span>52°.00</td></tr> +<tr><td class="blr">1828<span class="spacer2"> </span>55°.22</td> + <td class="br">1833<span class="spacer2"> </span>54°.56</td> + <td class="br">1838<span class="spacer2"> </span>50°.62</td> + <td class="br">1843<span class="spacer2"> </span>50°.77</td> + <td class="br">1848<span class="spacer2"> </span>52°.50</td></tr> +<tr><td class="blr">1829<span class="spacer2"> </span>52°.38</td> + <td class="br">1834<span class="spacer2"> </span>52°.40</td> + <td class="br">1839<span class="spacer2"> </span>52°.54</td> + <td class="br">1844<span class="spacer2"> </span>53°.25</td> + <td class="br">1849<span class="spacer2"> </span>52°.09</td></tr> +<tr><td class="bblr">1830<span class="spacer2"> </span>54°.93</td> + <td class="bbr">1835<span class="spacer2"> </span>50°.65</td> + <td class="bbr">1840<span class="spacer2"> </span>52°.35</td> + <td class="bbr">1845<span class="spacer2"> </span>52°.73</td> + <td class="bbr">1850<span class="spacer2"> </span>51°.48</td></tr> +<tr><td class="bblr">Mean<span class="spacer2"> </span>54°.29</td> + <td class="bbr">Mean<span class="spacer2"> </span>52°.18</td> + <td class="bbr">Mean<span class="spacer2"> </span>51°.52</td> + <td class="bbr">Mean<span class="spacer2"> </span>52°.35</td> + <td class="bbr">Mean<span class="spacer2"> </span>52°.32</td></tr></table> + +<p>The observations of Dr. Holyoke were made at Salem, Massachusetts; those +of Dr. Hildreth at Marietta, Ohio.</p> + +<p>The following, in relation to the freezing of the<span class="pagenum"><a name="Page_225" id="Page_225">[Pg 225]</a></span> Ohio River, is evidence +of a different kind, but shows the same general correspondence, and +particularly <i>the mildness of the winters when there were few spots</i>, and +their severity from 1836 to 1838, inclusive, when the spots were most +numerous:</p> + +<p class="thin">1829.—River open all winter—some floating ice.<br /> +1830.—River closed 27th January.<br /> +1831.—Floating ice—closed 23d January—opened 20th February.<br /> +1832.—Closed in December, which was a very cold month—opened January 8, and remained open all winter.<br /> +1833.—Open all winter.<br /> +1834.—Open all winter.<br /> +1835.—Closed January 6—opened the last of the month—cold.<br /> +1836.—Closed 28th January—opened 25th February.<br /> +1837.—Closed from 8th December to 8th February. Cold year.<br /> +1838.—Closed from 13th January to 13th March. Cold year.<br /> +1839.—Closed from 6th December to 13th January.<br /> +1840.—Closed 29th December—opened 15th January.<br /> +1841.—Closed 3d January—opened 8th do.<br /> +1842.—Open all winter.<br /> +1843.—Closed 28th November—opened 5th December—open all the rest of the winter.<br /> +1844.—Open all winter.<br /> +1845.—Open all winter.<br /> +1846.—Closed 5th December—opened again a few days—closed again on the 26th. It is not stated how long it remained closed.<br /> +1847.—Open all winter.<br /> +1848.—Much floating ice, but not closed—heavy rains and floods.<br /> +1849.—Floating ice in January, but not closed.<br /> +1850.—Floating ice, but not closed.<br /> +1851.—Open all winter—a little ice.<br /> +<br /> +(December in the above table, means December previous).</p> + +<p>This is more reliable as to the winter season than the tables of annual +means—although the evidence they afford, making due allowance for the +exceptions, is very striking.</p> + +<p>I shall return to this part of the subject again.</p> + +<p>But there is other evidence of the influence of these spots. Their +connection with the irregular<span class="pagenum"><a name="Page_226" id="Page_226">[Pg 226]</a></span> magnetic disturbance of the earth has been +distinctly traced. Colonel Sabine, President of the British Association, +in his opening address, September, 1852, after reviewing the recent +discoveries in magnetism, says:—</p> + +<div class="blockquot"><p>“It is not a little remarkable that this periodical magnetic +variation is found to be identical in period, and in epochs of maxima +and minima, with the periodical variation in the frequency and +magnitude of the <i>solar spots</i>, which M. Schwabe has established by +twenty-six years of unremitting labor. From a cosmical connection of +this nature, supposing it to be finally established, it would follow +that the decennial period, which we measure by our magnetic +instrument, is, in fact, a solar period, manifested to us, also, by +the alternately increasing and decreasing frequency and magnitude of +observations on the surface of the solar disc. May we not have in +these phenomena the indication of a cycle, or period of <i>secular +change in the magnetism of the sun</i>, affecting visibly his gaseous +atmosphere or photosphere, and sensibly modifying the magnetic +influence which he exercises on the surface of our earth?”—American +Journal of Science, new series, vol. xiv. p. 438.</p></div> + +<p>I think it may fairly be inferred, that although these spots do not +occasion the “cold spells” and “hot spells,” and other transient +peculiarities, they do materially affect the <i>mean</i> temperature of the +year, and exert an obvious influence when at their maxima; and there is a +tendency to an increase of the heat and dryness of summer, and the +severity of winter, at the periods named, in our excessive climate, and a +well-established connection between the spots and magnetic disturbances +and variations.</p> + +<p>Popular opinion has ever attributed to the moon a controlling effect upon +the changes of the weather. If it be dry, a storm is expected <i>when the +moon changes</i>; or if it be wet, dry weather. Such popular<span class="pagenum"><a name="Page_227" id="Page_227">[Pg 227]</a></span> opinions are +usually entitled to respect, and founded in truth. But every attempt to +verify <i>this opinion</i>, by careful observation and registration, has +failed. Weather-tables and lunar phases, compared for nearly one hundred +years, show four hundred and ninety-one new or full moons attended by a +change of the weather, and five hundred and nine without. The celebrated +Olbers, after <i>fifty years of careful observation</i> and comparison, decided +against it. So did the more celebrated Arago, at a more recent +date—summing up the result of his observations by saying—“Whatever the +progress of the sciences, never will observers, who are trustworthy and +careful of their reputation, venture to foretell the state of the +weather.” Still, the moon may influence the weather, though she may not +effect changes at her syzygies or quadratures, and this subject should not +be too summarily dismissed. That the moon can not effect changes at the +periods named seems philosophically obvious. She changes, for the <i>whole +earth</i>, within the period of twenty-four hours; yet, how varied the state +of things on different portions of its surface. The equatorial belts of +trades, and drought, and rains, cover from fifty to sixty degrees of its +surface, and know nothing of lunar disturbance. The extra-tropical belt of +rains and variable weather moves up in its season, uncovering 10°, or +more, of latitude, and admitting the trades and a six months’ drought over +it, as in California, regardless of the moon. Under the zone of +extra-tropical rains, even upon the eastern part of the continent of North +America, “dry spells”<span class="pagenum"><a name="Page_228" id="Page_228">[Pg 228]</a></span> and “wet spells” exist side by side; the focus of +precipitation is now in one parallel, and now in another—<i>storms</i> exist +<i>here</i> and <i>fair weather there</i>, on the same continent at the same time; +and as the moon’s rays in her northing pass round the northern hemisphere +during the twenty-four hours, they, doubtless, pass from ten to thirty or +more storms, of all characters and intensities, moving in opposition to +her orbit—and as many larger intervening areas of fair weather, not one +of which are indebted to her for their existence, or “take thought of her +coming.”</p> + +<p>The storm, which originates in the tropics, pursues its curving way now N. +W., then N. E., and again north, to the Arctic circle, and, perhaps, +around the magnetic pole, over gulf, and continent, and ocean, <i>occupying +one third the time of a lunation, and two changes, perhaps, in its +progress</i>, without any perceptible or conceivable influence from her. Yet +every inhabitant of mother-earth, influenced by <i>coincidences remembered</i>, +and uninfluenced by <i>exceptions forgotten</i>, looks up within his limited +horizon, and devoutly expects from the agency of some phase of the moon, a +change for the special benefit of his <i>dot</i> upon the earth’s surface. Upon +how many of these countless dots is the moon at a particular phase, or +relative distance from the sun, to change fair weather to foul, or foul to +fair? Upon none. The storms keep on their way;—the wet spells, and the +dry spells, the cold and the hot spells alternate in their time, and +though the moon turns toward them in passing, her dark face, her half +face, or her full orb (the<span class="pagenum"><a name="Page_229" id="Page_229">[Pg 229]</a></span> gifts of the sun, which confer no power), they +do not heed her. They are originated, and are continued, by a more potent +agent. They are the work of an atmospheric mechanism, as <i>ceaseless</i> in +its operation as <i>time</i>, as <i>regular</i> as the <i>seasons</i>, <i>as extensive as +the globe</i>.</p> + +<p>Indeed, it seems as if it was expressly designed by the Creator that the +moon should not interfere materially with this atmospheric machinery. She +is the nearest orb; her influence would be controlling and continuous; +would follow her monthly path from south to north, and with changes too +violent, and intervals too long; and would interfere with the regular +fundamental operation in the trade-wind region, where she is <i>vertical</i>. +Aside from the attraction of gravitation, therefore, she seems to have +been so created as to be incapable of exerting any influence. She is +without an atmosphere; the rays which she reflects are polarized, and +without chemical or magnetic power; and, if it be true that Melloni has +recently detected heat in them, by the use of a lens three feet in +diameter, which could not previously be effected, its quantity is +exceedingly small, and incapable of influence. Doubtless, the attraction +of her mass is felt upon the earth, as the tides attest; and upon the +atmosphere as well as the ocean. But the atmosphere is comparatively +<i>attenuated</i>, and exceedingly so at its upper surface. Her attraction, +therefore, although felt, is not influential. She seemed, to Dr. Howard, +to produce in her northing and southing, a lateral tide which the +barometer disclosed,<span class="pagenum"><a name="Page_230" id="Page_230">[Pg 230]</a></span> but owing to the attenuated character of the +atmosphere, neither the sun nor moon create an easterly and westerly tide, +that is observable, except with the most delicate instruments. Sabine is +believed to have detected such a tide by the barometer, at St. Helena, of +one four thousandth of an inch. But even this <i>infinitesimal influence</i> +may prove an error upon further investigation. There is a diurnal +variation of the barometer, but it is not the result of her attraction, +for it is not later each day as are the tides, exists in the deepest mines +as well as upon the surface, and is demonstrably connected with the +<i>group</i> of <i>diurnal</i> changes produced by the action of the sun-light and +heat upon the earth’s magnetism.</p> + +<p>Can the lateral tide, if there be one, affect the weather? for in the +present state of science it seems entirely certain that the moon can exert +an influence in no other way.</p> + +<p>If the received idea of many, perhaps most, meteorologists, on which all +wheel barometers are constructed, that a <i>high barometer</i> necessarily +produces <i>fair weather</i>, and a <i>low one foul</i>, were true, she certainly +might do so. But that idea can not be sustained, and there is no known +certain influence exerted by the moon upon the weather, in relation to +which we have any reliable practical data.</p> + +<p>Humboldt appears to have adopted the impression of Sir W. Herschell, that +the moon aids in the dispersion of the clouds. (Cosmos, vol. iv. p. 502.) +But the tendency to such dispersion is always rapid during the latter part +of the day and evening, when<span class="pagenum"><a name="Page_231" id="Page_231">[Pg 231]</a></span> there is no storm approaching, and the full +moon renders their dissolution visible, and attracts attention to them. +The Greenwich observations, also, carefully examined by Professor Loomis, +fail to confirm the impression of Herschell and Humboldt, and those +eminent philosophers are doubtless in this mistaken.</p> + +<p>From this general and somewhat desultory view of the general facts, which +bear analogically upon the question, no decisive inference can be drawn in +relation to the seat of the primary influence which produces the +atmospheric changes. The preponderance is in favor of the magnetic, or +magneto-electric, action of the earth. We must come back to our own +country and grapple with the question at home.</p> + + +<p> </p><p> </p> +<hr style="width: 50%;" /> +<p><span class="pagenum"><a name="Page_232" id="Page_232">[Pg 232]</a></span></p> +<h2><a name="CHAPTER_IX" id="CHAPTER_IX"></a>CHAPTER IX.</h2> + +<p>Before proceeding to do this, however, it may be well to look at some +theories which have been advanced, and to a greater or less extent +adopted, and at their bearing upon the question.</p> + +<p>The calorific theory is at present the prevailing one in Europe and in +this country. Meteorologists there and here refer all atmospheric +conditions and phenomena to the influence of heat. The principal +applications of that theory have been considered. But within the last few +years the elasticity and tension of the aqueous vapor of the atmosphere +have received much attention, as exerting an auxiliary or modifying +influence. Professor Dove, of Berlin, who ranks perhaps as the most +distinguished meteorologist of that continent, attributes barometric +variations to <i>lateral overflows</i>, and, in the upper regions, resulting +from the elevation of the atmosphere by expansion; and in this view +meteorologists of Europe seem generally to acquiesce. In an article sent +to Colonel Sabine, and recently republished in the American Journal of +Science, January, 1855, in thus attempting to account for the annual +variation of barometric pressure, which occurs in Europe and Asia, and, +indeed, over the entire hemisphere. He says:</p> + +<div class="blockquot"><p><span class="pagenum"><a name="Page_233" id="Page_233">[Pg 233]</a></span>“From the combined action or the variations of aqueous vapor, and of +the dry air, we derive immediately the periodical variations of the +whole atmospheric pressure. As the dry air and the aqueous vapor +mixed with it, press in common on the barometer, so that the up-borne +column of mercury consists of two parts, one borne by the dry air, +the other by the aqueous vapor, we may well understand that as with +increasing temperature the air expands, and by reason of its +augmented volume rises higher, and <i>its upper portion overflows +laterally</i>,” etc.</p></div> + +<p>And in another place he says:</p> + +<div class="blockquot"><p>“From the magnitude of the variations in the northern hemisphere, and +the extent of the region over which it prevails, we must infer that +<i>at the time of diminished pressure a lateral overflow probably takes +place</i>,” etc.</p></div> + +<p>Doubtless, the mean pressure of the atmosphere, in summer, in the northern +hemisphere, is less than in winter, in some localities, and greater in +others, and it differs in different countries of equal temperature. And +this is all very intelligible. The mean of the pressure for the month is +made up by <i>averaging</i> all the <i>elevations</i> and <i>depressions</i>. During a +month, showing a very low mean, the barometer may, at times, attain its +<i>highest altitude</i>, if the depressions below the mean are great or more +frequent. The barometer is depressed during storms, and ranges high during +<i>set fair</i> weather. Ordinarily, therefore, the more stormy the season the +more diminished the mean pressure; and it is a mistake to look to an +overflow to account for the fact. The changes in the location of the +atmospheric machinery, and consequent change in the amount and severity of +falling weather, and the periodic frequency and character of storms, and +consequent <i>periodic</i> depressions<span class="pagenum"><a name="Page_234" id="Page_234">[Pg 234]</a></span> and elevations of the barometer, +explain the annual mean variations, as they do the other phenomena. But it +is perfectly consistent with the calorific theory to attempt to account +for these differences by another of those ever-necessary modifications, +viz.: the different tension and elasticity of aqueous vapor in different +countries of equal temperature; and then to <i>suppose</i> an expansion of the +whole body of the atmosphere and a lateral overflow from the place where +the air is expanded, on to some other, where it is not; and thus <i>suppose</i> +all necessary currents in the upper regions, setting hither and yon, by +the force of gravity alone. And apparently he who is best at supposition +becomes the most distinguished meteorologist. Perhaps I have already said +all that I ought to be pardoned for saying, in relation to the utter +absurdity of attributing all meteorological phenomena to the agency of +heat; but when I find such views as those which that article contains, +emanating from so distinguished a man, sanctioned by the President of the +British Association, and copied into the leading journal of science in +this country, I can not forbear a further and a somewhat critical +examination of them. There is more error of supposition and less truth in +it, than in any other article regarding the science, of equal length, +which has fallen under my notice.</p> + +<p>What is the height of this expansion? The moisture of evaporation ascends, +ordinarily, but a few thousand feet. The atmosphere grows regularly +cooler, from the earth to the trade, and <i>the increased warmth that is +felt at the surface extends but little way</i>. Currents of<span class="pagenum"><a name="Page_235" id="Page_235">[Pg 235]</a></span> warm air do not +ascend. The strata maintain, substantially, their relative positions; and +this is a most beneficent provision. In northern latitudes of the +temperate zone, all the warmth derived from a few hours’ sunshine is +needed at the surface; and, deplorable, indeed, would be our condition, if +the atmosphere, as fast as warmed by the rays of the sun, were to hasten +up, and the frigid strata descend in its place. The earth would not be +habitable. All the warm air on its surface would be rising as soon as it +became warmed, and the cold air above be descending, and enveloping us +with the chilling strata which are ever floating within two or three miles +above us. No. Infinite wisdom has ordered it otherwise. The laws of +magnetism and of static-electric induction and attraction keep the strata +in their places, and preserve to us the warmth which the solar rays afford +or produce. The inhabitant of the valley, in a high northern latitude, in +summer, can plant, and sow, and reap, at the base of the mountain whose +summit penetrates the stratum of continual congelation, and up its sides, +almost to the line of perpetual snow; and, as he looks upon the fruits of +his labor, and up to the snow-clad peak that towers above him, can thank +his Maker for placing a warm equatorial current, a perpetual barrier, +between the fertility and warmth which surround him, and the cold +destructive strata above; and thank Him for not creating such a state of +things, as certain meteorologists insist we shall believe He has created. +Again, where are the <i>upper regions</i>, from which the<span class="pagenum"><a name="Page_236" id="Page_236">[Pg 236]</a></span> lateral overflow +takes place? The atmosphere is differently estimated, at from thirty to +forty-five miles, or more, in height. Whatever its height may be, it is +exceedingly attenuated in its “upper regions.”</p> + +<p>Gay-Lussac marked the barometer at 12<span style="font-size: 0.8em;"><sup>95</sup></span>⁄<span style="font-size: 0.6em;">100</span> inches at the height of +23,040 feet. Two thirds of the atmospheric density, then, is within five +miles of the earth. Air, too, is <i>compressible</i>. Allowing for the latter +and the attenuation, how many miles in vertical depth, of its “<i>upper +regions</i>,” must move from one portion to another, to depress the barometer +two inches—its range sometimes in twenty-four hours—or even half an +inch? Let the computation be made, and see how startling the proposition, +how utterly impossible that the theory can be true.</p> + +<p>The distinguished Professor, in the paper referred to, introduces his +theory of the formation of hurricanes, and we quote—</p> + +<div class="blockquot"><p>“If we suppose the upper portions of the air ascending over Asia and +Africa to flow off laterally, and if this takes place suddenly, it +will check the course of the upper or counter-current above the +trade-wind, and force it to break into the lower current.</p> + +<p>“An east wind coming into a S. W. current must necessarily occasion a +rotatory movement, turning in the opposite direction to the hands of +a watch. A rotatory storm, moving from S. E. to N. W., in the lower +current or trade, would, in this view, be the result of the encounter +of two masses of air, impelled toward each other at many places in +succession, the further cause of the rotation (originating primarily +in this manner) being that described by me in detail in a memoir ‘On +the Law of Storms,’ translated in the ‘Scientific Memoirs,’ vol. iii. +art. 7. Thus, it happens that the West India hurricanes, and the +Chinese typhoons occur near the lateral confines on either side of +the great region of atmospheric expansion, the typhoons being +probably occasioned by the direct pressure of the air from the region +of the trade-winds over the Pacific, into the more<span class="pagenum"><a name="Page_237" id="Page_237">[Pg 237]</a></span> expanded air of +the monsoon region, and being distinct from the storms appropriately +called by the Portuguese ‘temporales,’ which accompany the out-burst +of the monsoon when the direction of the wind is reversed.”</p></div> + +<p>The analogy between this, and a theory of Mr. Redfield’s, will be noticed +further on. But I remark, in passing, that there is not a fact or +inference in this paragraph which will bear examination.</p> + +<p>1. There is no such regular S. W. wind over the surface trade, as he +supposes. Doubtless, there are, occasionally, secondary S. W. currents +between the counter-trade and the surface one, with partial condensation, +for much of both becomes depolarized by their reciprocal action and +precipitation, and these induced S. W. currents are sometimes so strong as +to usurp the place of the surface-trade, and become very violent in the +latter part of hurricanes; but such is not the usual course of the upper +currents of the West Indies, as the progress of storms there, and +observation, prove.</p> + +<p>2. There can not be any <i>periods</i> of extensive and <i>sudden</i> expansion over +Africa. If there is any place on the earth which has a more uniformly +progressive temperature, either way, and is more free from <i>sudden</i> +extremes, or which is more arid and destitute of aqueous vapor, and sudden +aqueous expansions, than another, it is Africa. No such occasional sudden +expansions are there possible.</p> + +<p>3. Winds do not, and can not, “<i>encounter</i>.” They stratify upon each +other. They are produced by the action of opposite electricity, and are +<i>connected together</i><span class="pagenum"><a name="Page_238" id="Page_238">[Pg 238]</a></span> in their origin and action. The atmosphere is never +free from the regular and irregular currents, however invisible for the +want of condensation. Aeronauts find them in the most serene days. They +exist without encounter or tendency to rotation, every where, and at all +times; even over the head of the distinguished Professor, whether he +sleeps or is awake. We can all see them when there is condensation, and it +is rarely the case that there is not some degree of it in some of them.</p> + +<p>4. That “Great region of expansion” is a chimera. It does not exist. It is +a region of <i>lower temperature</i>, and of <i>condensation</i>, instead of +<i>expansion</i> of <i>aqueous vapor</i>. The trade does not rise in it, or the S. +W. wind overflow from it. See the table cited page <a href="#Page_165">165</a>.</p> + +<p>5. The hurricanes do not originate <i>in the surface trades</i>, as he +supposes. They originate in the belt of rains, the supposed “region of +expansion,” and issue out of it; or in the counter-trade, where volcanic +elevations rise far into or above the surface trade.</p> + +<p>6. This hypothesis can not be sustained upon his own principles. The +distance between Africa and the West India Islands, where most of the +hurricanes originate, is from 2,500 to 3,000 miles. These gales are small +when they commence, not ordinarily over one or two hundred miles in +diameter, and often less. There are trades all the way over from Africa, +and S. W. winds also, if they exist, as he supposes, in the West Indies. +How can it happen that this lateral overflow should pass <i>without effect</i>, +over 2,500 miles of S. W. wind and trade, and concentrating the overflow<span class="pagenum"><a name="Page_239" id="Page_239">[Pg 239]</a></span> +of a continent over one small and chosen spot of the West Indies, <i>pitch +down</i> there, and there only, and crowd the S. W. wind into the trade +below? This is too much for sensible men to believe.</p> + +<p>What does Professor Dove mean by the term <i>impulsion</i>, as applied to the +winds? How are they <i>impelled</i>? It is the fundamental idea of his +calorific theory, that they are <i>drawn</i> by the <i>suction</i> caused by a +<i>vacuum</i>, and the vacuum created by expansion and overflow above, in +obedience to the law of gravity; that the S. E. trade is drawn to the +great region of expansion, and the S. W. runs from it as an overflow. But +if the S. W. is driven down into the plane and place of the +surface-trades, how does it continue to be impelled, and why is it not +then subject to the suction of the vacuum which draws the trade? Does that +vacuum <i>select its air</i>, and so attract the trade, in preference to the +depressed portion of the S. W. current, that the former runs around the +latter to get to the vacuum, and the latter around the former to get away +from it? And does the trade, when it has got around the S. W. current, +instead of going to the vacuum, continue to gyrate, and the S. W. current, +instead of pursuing its regular course, gyrate also about the trade, and +both move off together, regardless of the vacuum of the great region of +expansion, in a new direction to the N. W., in an independent, +self-sustaining, cyclonic movement, increasing in power and extent, +involving extended and increasing condensation, producing the most violent +electrical phenomena, and thus continuing up, even to the<span class="pagenum"><a name="Page_240" id="Page_240">[Pg 240]</a></span> Arctic circle? +Yes, says Professor Dove. No, say all fact, all analogy, and his own +principles.</p> + +<p>7. His theory relative to the typhoons is unintelligible. If they +originate near the lateral confines of the great region of atmospheric +expansion, they originate in the region of the trade-winds, for the two +are identical. How the direct pressure of the air from the trade-wind over +the Pacific, in the more expanded air of the monsoon region, can occasion +a typhoon upon any principles, passes my comprehension. If, as Lieutenant +Maury supposes, the monsoons are reversed trades, then the trade-wind and +monsoon region are identical. If the monsoons are found in the belt of +rains, then, the trades, upon Professor Dove’s principles, pass into the +monsoon region by attraction or suction, without pressure. Either way the +theory is undeserving of consideration.</p> + +<p>A new theory has recently been started by Mr. Thomas Dobson, and, although +it is (like all other efforts to get the <i>upper strata down</i> to produce +condensation, or those below <i>up</i>, that they may be condensed), without +foundation, his collection of facts is brief and interesting. I copy his +article from the London, Edinburgh, and Dublin Phil. Mag., for December, +1853. It adds to the collection of facts in relation to the connection +between volcanic action and storms for the <ins class="correction" title="original: sevententh">seventeenth</ins> century, made by +Dr. Webster:</p> + +<div class="blockquot"><p>The following appear to be the main facts which are available as a +basis for a theory which shall comprehend all the meteors in +question:</p> + +<p><span class="pagenum"><a name="Page_241" id="Page_241">[Pg 241]</a></span>1st. The eruption of a submarine volcano has produced water-spouts.</p> + +<p>“During these bursts the most vivid flashes of lightning continually +issued from the densest part of the volcano, and the volumes of smoke +rolled off in large masses of fleecy clouds, gradually expanding +themselves before the wind in a direction nearly horizontal, and +drawing up <i>a quantity of water-spouts</i>.”—(Captain Tilland’s +description of the upheaval of Sabrina Island in June, 1811, Phil. +Trans.)</p> + +<p>With this significant fact may be compared the following analogous +ones:</p> + +<p>“In the Aleutian Archipelago a new island was formed in 1795. It was +first observed <i>after a storm</i>, at a point in the sea from which a +column of smoke had been seen to rise.”—(Lyell, Principles of +Geology.)</p> + +<p>“Among the Aleutian Islands a new volcanic island appeared in the +midst of <i>a storm</i>, attended with flames and smoke. After the sea was +calm, a boat was sent from Unalaska with twenty Russian hunters, who +landed on this island on June 1st, 1814.”—(Journal of Science, vol. +vii.)</p> + +<p>“On July 24th, 1848, a submarine eruption broke out between the +mainland of Orkney and the island of Strousa. Amid thunder and +lightning, a very dense jet black cloud was seen to rise from the +sea, at a distance of five or six miles, which <i>traveled toward the +north-east</i>. On passing over Strousa, the wind from a slight air +became <i>a hurricane</i>, and a thick, well-defined belt of large +hailstones was left on the island. The barometer fell two +inches.”—(Transactions Royal Society, Edinburg, vol. ix.)</p> + +<p>2d. Hurricanes, whirlwinds, and hailstones accompany the paroxysms of +volcanos.</p> + +<p>“1730. A great volcanic eruption at Lancerote Island, and <i>a storm</i>, +which was equally new and terrifying to the inhabitants, as they had +never known one in the country before.”—(Lyell, Principles of +Geology, vol. ii.)</p> + +<p>“1754. In the Philippine Islands a terrible volcanic eruption +destroyed the town of Taal and several villages. Darkness, +hurricanes, thunder, lightning, and earthquakes, alternated in +frightful succession.”—(Edinburgh Philosophical Journal.)</p> + +<p>“In 1805, 1811, 1813, and 1830, during eruptions of Etna, caravans in +the deserts of Africa perished by violent whirlwinds. In 1807, while +Vesuvius was in eruption, a whirlwind destroyed a caravan.”—(Rev. W. +B. Clarke in Tasw. Journal.)</p> + +<p>“1815, Java. A tremendous eruption of Tombow Mountain. Between nine +and ten <span class="smcaplc">P.M.</span>, ashes began to fall, and soon after <i>a<span class="pagenum"><a name="Page_242" id="Page_242">[Pg 242]</a></span> violent +whirlwind</i> took up into the air the largest trees, men, horses, +cattle, etc.”—(Raffles’ History of Java.)</p> + +<p>“1817, Dec. Vesuvius in eruption. In the evening <i>a hail storm</i>, +accompanied with red sand.”—(Journal of Science, vol. v.)</p> + +<p>“1820, Banda. A frightful volcanic eruption, and in the evening an +earthquake and a violent hurricane.”—(Annales de Chimie.)</p> + +<p>“1822, Oct. Eruption of Vesuvius. Toward its close the volcanic +thunder-storm produced an exceedingly violent and abundant fall of +rain.”—(Humboldt, Aspects of Nature.)</p> + +<p>“1843, Jan. Etna in eruption. Violent hurricanes at Genoa, in the Bay +of Biscay, and in Great Britain.</p> + +<p>“1843, Feb. Destructive earthquakes in the West Indies, a volcanic +eruption at Guadaloupe, followed by hurricanes in the Atlantic.”</p> + +<p>“1846, June 26. Volcano of White Island, New Zealand, in eruption. +Heavy squalls of wind and hail; it blew as hard as in a +typhoon.”—(Commodore Hayes, R.N., in Naut. Mag., 1847.)</p> + +<p>“1847, March 20. Volcanic eruption and earthquake in Java; and on the +21st of March, and 3d of April, violent hurricanes.”—(Java Courant.)</p> + +<p>“1851, Aug. 5. A frightful eruption of the long dormant volcano of +the Pelée Mountain, Martinique. Aug. 17. Hurricane at St. Thomas, +etc.; earthquake at Jamaica, etc.</p> + +<p>“1852, April 14. Earthquake at Hawaii, and on the 15th a great +volcanic eruption. On the 18th <i>a gale of unusual violence</i> lasted +thirty-six hours, and did great damage.”—(The Polynesian, April 22, +1852.)</p> + +<p>3d. In volcanic regions, earthquakes and hurricanes often occur +almost simultaneously, but in no certain order, and without any +volcanic eruption being observed.</p> + +<p>In 1712, 1722, 1815, and 1851, earthquakes and hurricanes occurred +together at Jamaica; in 1762 at Carthagena; in 1780 at Barbadoes; in +1811 at Charleston; in 1847 at Tobago; in 1837 and 1848 at Antigua; +in 1819, an awful storm at Montreal, rain of a dark inky color, and a +slight earthquake. People conjectured that a volcano had broken out. +In 1766 the great Martinique hurricane, a <i>waterspout</i> burst on Mount +Pelée and overwhelmed the place. Same night, an earthquake.</p> + +<p>1843, Oct. 30. Manilla.—Twenty four hours’ rain and two heavy +earthquakes. 10 <span class="smcaplc">P.M.</span>, a severe hurricane.</p> + +<p>“1852, Sept. 16. Manilla—An earthquake destroyed a great part of the +city; many vessels wrecked by a great hurricane in the adjacent seas, +between the 18th and 26th of September.”—(Singapore Times.)</p> + +<p><span class="pagenum"><a name="Page_243" id="Page_243">[Pg 243]</a></span>“1731, Oct. Calcutta.—Furious hurricane and violent earthquake; +300,000 lives lost.”</p> + +<p>“1618, May 26. Bombay.—Hurricane and earthquakes; 2,000 lives +lost.”—(Madras Lit. Tran., 1837.)</p> + +<p>“1800. Ongole, India, and in 1815, at Ceylon, a hurricane and +earthquake shocks.”—(Piddington.)</p> + +<p>“<ins class="correction" title="Presented as in the original.">1348.</ins> Cyprus.—An earthquake and a frightful hurricane.”—(Hecker.)</p> + +<p>“1819. Bagdad.—An earthquake and <i>a storm</i>—an event quite +unprecedented.</p> + +<p>“1820, Dec. Zante.—Great earthquake and hurricane, with +manifestations of a submarine eruption.”—(Edinburg Phil. Journal.)</p> + +<p>“1831, Dec. Navigator’s Islands.—Hurricane and +earthquakes.”—(Williams’ Missionary Enterprise.)</p> + +<p>“1848, Oct., Nov. New Zealand.—Succession of earthquake shocks, and +several tempests.</p> + +<p>“1836, Oct. At Valparaiso, a destructive tempest and severe +earthquakes.”—(Nautical Magazine, 1848.)</p> + +<p>When an earthquake of excessive intensity occurs, as at Lisbon, in +1755, the volcanic craters, which act as the safety-valves of the +regions in which they are placed, are supposed to be sealed up; and +it is a remarkable and highly-suggestive fact, that <i>no hurricane +follows such an earthquake</i>. The number of instances of the +concurrence of ordinary earthquakes and hurricanes might easily be +increased, but the preceding suffice to show the <i>generality</i> of +their coincidence, both as <i>to time</i> and place.</p> + +<p>4th. The breaking of water-spouts on mountains sometimes accompanies +hurricanes.</p> + +<p>In 1766, during the great Martinique hurricane, before cited.</p> + +<p>“1826, Nov. At Teneriffe, enormous and most destructive water-spouts +fell on the culminating tops of the mountains, and a furious cyclone +raged around the island. The same occurred in 1812 and in +1837.”—(Espy and Grey’s Western Australia.)</p> + +<p>“1829. Moray.—Floods and earthquakes, preceded by water-spouts and a +tremendous storm.”—(Sir T. D. Lander.)</p> + +<p>“1826, June. Hurricanes, accompanied by water-spouts and fall of +avalanches, in the White Mountains.”—(Silliman’s American Journal, +vol. xv.)</p> + +<p>5th. The fall of an avalanche sometimes produces a hurricane.</p> + +<p>“1819, Dec. A part (360,000,000 cubic feet) of the glacier fell from +the Weisshorn (9,000 feet). At the instant, when the snow and ice +struck the inferior mass of the glacier, the pastor of the village of +Randa, the sacristan, and some other persons, <i>observed a light</i>. A<span class="pagenum"><a name="Page_244" id="Page_244">[Pg 244]</a></span> +frightful hurricane immediately succeeded.”—(Edinburg Philosophical +Journal, 1820.)</p> + +<p>6th. Water-spouts occur frequently near active volcanos.</p> + +<p>This is well known with regard to the West Indies and the +Mediterranean. The following notices refer to the Malay Archipelago +and the Sandwich Islands:</p> + +<p>“Water-spouts are often seen in the seas and straits adjacent to +Singapore. In Oct., 1841, I saw <i>six</i> in action, attached to one +cloud. In August, 1838, one passed over the harbor and town of +Singapore, dismasting one ship, sinking another, and carrying off the +corner of the roof of a house, in its passage landward.”—(Journal of +Indian Archipelago.)</p> + +<p>“1809. An immense water-spout broke over the harbor of Honolulu. A +few years before, one broke on the north side of the island (Oahu), +washed away a number of houses, and drowned several +inhabitants.”—(Jarves’ History of Sandwich Islands.)</p> + +<p>7th. Cyclones begin in the immediate neighborhood of active volcanos.</p> + +<p>The Mauritius cyclones begin near Java; the West Indian, near the +volcanic series of the Caribbean Islands; those of the Bay of Bengal, +near the volcanic islands, on its eastern shores; the typhoons of the +China Sea, near the Philippine Islands, etc.</p> + +<p>8th. Within the tropics, cyclones move toward the west; and, in +middle latitudes, cyclones and water-spouts move toward the N. E., in +the northern hemisphere, and toward the S. E. in the southern +hemisphere.</p> + +<p>9th. In the northern hemisphere, cyclones rotate in a horizontal +plane, in the order N. W., S. E.; and in the southern hemisphere, in +the order N. E., S. W.</p> + +<p>By applying the principles of electro-dynamics to the electricity of +the atmosphere, I shall endeavor to connect and explain the preceding +well-defined facts. The continuous observations of Quetelet, on the +electricity of the atmosphere, from 1844 to 1849 (Literary Journal, +February, 1850), show that it is always positive, and increases as +the temperature diminishes. It therefore increases rapidly with the +height above the earth’s surface. We may, consequently, regard the +upper and colder regions of the atmosphere as an immense reservoir of +electric fluid enveloping the earth, which is insulated by the +intermediate spherical shell formed by the lower and denser +atmosphere. Now, whenever a vertical column of this atmosphere is +suddenly displaced, the surrounding aqueous vapor will be immediately +condensed and aggregated, and the cold rarefied air and moisture will +form a vertical conductor for the descent of the electrical fluid. +This <span class="pagenum"><a name="Page_245" id="Page_245">[Pg 245]</a></span>descent will take place down a spiral, gyrating in the order N. +W., S. E., in the northern hemisphere, since the electric current is +under the same influence as that of the south pole of a magnet; and +in the order N. E., S. W., in the southern hemisphere. The air +exterior to the conducting cylinder will partake of the violent +revolving motion, and a tornado or cyclone will be produced.</p></div> + +<p>Upon the foregoing facts I shall comment in another place.</p> + +<p>Three theories have been advanced by meteorologists of this country, two +of which profess to explain all the phenomena of the weather. Professor +Espy attributed the production of storms and rain to an ascending column +of air, rarefied by heat, and the rarefaction increased by the latent heat +of vapor given out during condensation, and an inward tendency of the air, +from all directions, toward the ascending vortex, constituting the +prevailing winds. Thus, Professor Espy conceived, and to some extent +proved, that the wind blew inward, from all sides, toward the center of a +storm, either as a circle, or having a long central line, and he conceived +that it ascended in the middle, and spread out above; and that clouds, +rain, hail, and snow, were formed by condensation consequent upon the +expansion and cooling of the atmosphere, as it attained an increased +elevation.</p> + +<p><i>This ascent</i> was not, in fact, <i>proved</i> by Professor Espy, <i>has not been +found by others</i>, and <i>is not discoverable, according to my observations</i>. +The theory was ingenious, founded on the theory of Dalton, that the vapor +was maintained in the atmosphere by reason of a large quantity of latent +heat, which was given<span class="pagenum"><a name="Page_246" id="Page_246">[Pg 246]</a></span> out when condensation took place. This theory is +also unsound. No such elevation of temperature is found in clouds or fogs +when they form near the earth, however dense. Thus the two principal +elements of Professor Espy’s theory are found to be untrue, and the theory +untenable. But it was sustained with great ability and research, and the +distinguished theorist deserves much for the discovery and record of +important facts in relation to the weather. Aside from its theoretical +views, his book contains a great mass of valuable information, and will +well repay the cost of purchase and perusal.</p> + +<p>Another theory, by Mr. Bassnett, is of recent date, founded on the +influence of the moon, and the supposed creation of vortices in the ether +above, whose influence extends to the earth, producing storms and other +phenomena. No one can peruse his book without conceding to him great +ability and scientific attainment; and if his theory was true, the periods +of fair and foul weather could be calculated with great mathematical +certainty. But it contains inherent and insuperable objections. I will +only add that all herein before contained is in direct opposition to it.</p> + +<p>Mr. W. C. Redfield, of New York, as early as 1831, first advanced in this +country the theory of gyration in storms, and investigated their lines of +progress on our coast and continent. His theory is limited in its +character, and does not profess, except indirectly, to explain all, or +indeed any, of the other phenomena of the weather. As far as it goes, +<span class="pagenum"><a name="Page_247" id="Page_247">[Pg 247]</a></span>however, it is generally received in this country and Europe, and has +been adopted by Reed, Piddington, and others, who have written on the law +of storms. The position of Mr. Redfield is honorable to himself and his +country. Science and navigation are much indebted to him for his industry +in the collection of facts. Nevertheless, his theory is not in accordance +with my observation, and I deem it unsound. Although expressed disbelief +of the theory has been characterized as an “attack” upon its author, I +propose, with that <i>respect</i> which is due to him, but with that <i>freedom</i> +and <i>independence</i> which a search for <i>truth</i> warrants, to examine it with +some particularity. It is a part of the subject, and I can not avoid it.</p> + +<p>When the theory was first announced, I adopted it as probably true; and +being then engaged in a different profession, which took me much into the +open air by night and day, I watched with renewed care the clouds and +currents for evidence to confirm it. I discovered none; on the contrary, I +found much, very much, absolutely and utterly inconsistent with its truth. +The substance only of these observations will be adduced.</p> + +<p>Mr. Redfield admits that the progression of our storms in the vicinity of +New York, is from some point between S. S. W. and W. S. W., to some point +between N. N. E. and E. N. E. According to my observation, except perhaps +in occasional autumnal gales, they are not often, if ever, from S. of S. +W., and the great majority of them, including, I believe, all N. E. +storms, are between S. W. and W. S. W.<span class="pagenum"><a name="Page_248" id="Page_248">[Pg 248]</a></span> Now, the card of Mr. Redfield, +moving over any place from any point between S. W. and W. S. W., calls for +a S. E. wind at its axis, an E. wind at its north front, and a S. wind at +its south front, and does not call <i>for a N. E. wind on its front at all, +except at the north extreme</i>, where it could <i>not continue for any +considerable period</i>.</p> + +<p> </p> +<p class="center"><strong>Fig. 17.</strong></p> +<div class="figcenter"><img src="images/fig17.jpg" alt="" /></div> +<p> </p> + +<p>In relation to this, I observe, 1st. <i>About one-half of our N. E. storms, +including some of the most severe ones, not only set in N. E., but +continue in that quarter without veering at all, during the entire period +that the storm cloud is over us</i>; usually for twenty-four hours; not +unfrequently for forty-eight hours, sometimes for seventy-two or more +hours. This every one can observe for himself, and it can not, of course, +be reconciled with his theory.</p> + +<p><span class="pagenum"><a name="Page_249" id="Page_249">[Pg 249]</a></span>2d. N. E. storms, whether they set in from that quarter in the +commencement, or veer to it afterward, when they do “change” round, more +frequently veer by the S. to the S. W. in clearing off, than back through +the N. into the N. W. The former, in accordance with his theory, they can +not do, as the reader can see by passing the left side of the card over +his place of residence on the map from S. W. to N. E.</p> + +<p>3d. N. E. storms often pass off without hauling by S. or backing by N., +and with or without a clearing off shower, the <i>wind shifting and coming +out suddenly at S. W.</i> This they could not do in accordance with his +theory, as slipping the card will show.</p> + +<p>4th. From June to February it is <i>exceedingly uncommon</i> for a N. E. storm +to back into the N. W. They do so more frequently from February to May, +especially about the time of the vernal equinox and after; and then, +because the focus of precipitation and storm intensity of the extra +tropical zone of rains is S. of 42° east of the Alleghanies. His theory +requires them to back by N. into N. W. <i>in all cases, when they set in N. +E.</i></p> + +<p>5th. When they do back from the N. E. into the N. W., it rarely indeed +continues to storm after the wind leaves the point of N. E. by N., and +generally, if it does continue stormy, <i>the wind is light</i>, and not a +gale, how violent soever the gale from the eastward may have been. +Usually, by the time the wind gets N. W., it has cleared off. This, Mr. +Redfield, as we shall see, evades by embracing the N. W. fair<span class="pagenum"><a name="Page_250" id="Page_250">[Pg 250]</a></span> wind as a +part of the same gale. According to my observation, therefore, a <i>very +large proportion</i> of the <i>N. E. storms</i>, and they are a majority of the +most violent ones of our climate east of the Alleghanies, do not +<i>commence, continue</i>, or <i>veer</i> in accordance with his theory, but the +<i>reverse</i>; and so long as this is so, I can not receive his theory as +true.</p> + +<p>6th. S. E. storms do not always, or indeed often, conform to the +requirements of his card. When they set in violently at S. E., and +continue so for hours without veering, the axis of the storm should be +over us, and the wind should change <i>suddenly</i> to N. W. This did not occur +in the storm of Sept. 3, 1821, nor does it often, if ever, occur in the +summer or early gales of the autumnal months. In the later storms of +autumn, and as often in those which are very gentle as any, and in the +winter months when S. E. gales are rare, it does sometimes so change after +the storm cloud has passed. But in the winter months, as in the storm +investigated by Professor Loomis, the storms are frequently long from S. +E. to N. W., and the S. E. wind blows nearly in coincidence with its long +axis, for a thousand or fifteen hundred miles, till the barometric minimum +is passed, and the inducing and attracting force of this part of the storm +cloud is spent, and then the N. W. wind follows; sometimes blowing in +under the storm cloud, turning the rain to snow; but oftener following the +storm within a few hours, or the next day. The storm of Professor Loomis, +when over Texas, was not probably more than four or five hundred miles in +length. As it<span class="pagenum"><a name="Page_251" id="Page_251">[Pg 251]</a></span> curved more, and passed north and east, it extended +laterally, its center traveling with most rapidity, and when it reached +the eastern coast was about fifteen hundred miles long, and not more than +six hundred broad. Along the eastern part of that storm, except when by +its more rapid progress the front projected much further eastward over New +England than its previously existing line, the S. E. winds blew. When it +bulged out, so to speak, by reason of the increased progress of the +center, the wind veered to the N. E. The center of the storm passed near +St. Louis and south of Quebec, as the <i>fall of rain</i>, the <i>bulging</i> of the +<i>rapidly-moving center</i>, and the <i>line of subsequent cold</i>, attest. It is +utterly impossible for any unbiased mind to look at the description of +that storm, and attribute to it a rotary character. With all the data +before him, Mr. Redfield himself has not attempted it directly.<small><a name="f8.1" id="f8.1" href="#f8">[8]</a></small></p> + +<p>The September storm of 1821 was more violent in character than any which +have since occurred. My recollection of it is as distinct as if it +occurred yesterday. Peculiar circumstances, not important in this +connection, fixed my attention upon the weather during that day and night. +There were cirro-stratus clouds passing all day, from about S. W. to N. +E., thickening toward night with fresh S. S. W. wind and flocculent scud, +such as I have since seen at the setting-in of S. E. autumnal gales. In +the evening the wind (in the immediate neighborhood of Hartford, Ct.), +veered to S. E., the cloud floated low, it became very dark, and the wind +blew a most<span class="pagenum"><a name="Page_252" id="Page_252">[Pg 252]</a></span> violent gale. The trees were falling about the house where I +then resided, the windows were burst in, and I was up and observant. When +the cloud passed off to the east, it was suddenly light, and almost calm. +The western edge of the storm cloud was as perpendicular as a steep +mountain side, and was enormously elevated, and very black. I have +sometimes seen the western side of a summer thunder cloud, which had drawn +a violent gust along beneath it, as elevated and perpendicular, but never +a storm cloud. No cloud of that <i>depth</i>, or <i>intensity</i> as exhibited by +its peculiar blackness, ever floated or will float so near the earth, +without inducing a devastating current beneath. After it had passed the +ridges east of the Connecticut valley, its top could be seen for a long +and unusual period over the elevated ranges.</p> + +<p>Now that storm was but an <i>intense portion</i> of an extensive stratus-rain +cloud. Such portions frequently exist, and Mr. Redfield admits the fact. +Another like portion, in the same storm, passed over Norfolk, Virginia, +and the adjacent section, where the wind was N. E., and veered round by N. +W. to S. W. Baltimore, and some vessels at sea, were between the two +intense portions of the storm, and were not affected by either. Its +northern limit was bounded by a line, drawn from some point not far north +of Trenton, New Jersey, north-eastward, and north of Worcester, +Massachusetts. I was about forty miles south of its northern limit, and +north of its center. During that day, and the next, there was<span class="pagenum"><a name="Page_253" id="Page_253">[Pg 253]</a></span> wind from +S. W. to S. E., inclusive, including the gale, and <i>from no other +quarter</i>. It did not at any time veer to the W. or N. W. After the passage +of the storm-cloud, the wind was very light. When this intense portion of +the storm passed over the valley of the Connecticut, its longest axis was +from S. S. E. to N. N. W., and the <i>wind was S. E. the whole length of +it</i>. In its passage from the longitude of Trenton to Boston, there was N. +W. wind at one point, and but one, and that was in the iron region, at the +N. W. corner of Connecticut, at the northern limit of the intense cloud, +and owing, doubtless, to some local cause. The direction of the wind in +that storm was in accordance with what is generally true of our storms. +The wind on the front of the storm depends upon its shape. If the storm is +long in proportion to its width (and no other <i>violent</i> autumnal or winter +storm has been investigated, to my knowledge), the wind blows axially, or +obliquely, on its front. Thus, if long from S. E. to N. W., the wind on +its front will blow from the S. E. So, if the storm is long from S. W. to +N. E., and has a south-eastern lateral extension, with an easterly +progression, the wind will blow axially in the center, and obliquely at +the edges. Instances might be multiplied, but I refer to one of recent +date and striking character. All of us remember the drought of 1854. It +ended in drenching rain on the 9th of September. This rain fell from a +belt, half showery and half stormy in character, which had a S. E. lateral +extension.</p> + +<p><span class="pagenum"><a name="Page_254" id="Page_254">[Pg 254]</a></span>The evening of the previous day there was some lightning visible at the +north, and the usual S. S. W. afternoon wind <i>continued fresh after +nightfall</i>. The next day we had a brisk wind from the same quarter, and, +after noon, the clouds appeared to pile up in the far north, seeming very +elevated. They continued to do so, extending southerly during the +afternoon, <i>with a high wind from S. S. W.</i>, the cumulus clouds moving E. +N. E. At 5 <span class="smcaplc">P.M.</span>, gentlemen who left New York at 3 <span class="smcaplc">P.M.</span>, reported that a +dispatch had been received from Albany, dated 1 <span class="smcaplc">P.M.</span>, stating that it was +raining very heavily there. About 7 <span class="smcaplc">P.M.</span>, the belt reached us, and it +rained heavily from that time till morning. Not far from 8 <span class="smcaplc">P.M.</span>, and +during the heaviest rain, the wind shifted from the S. S. W. to N. E., and +blew fresh and cold from that quarter during the night, and till the belt +had passed south, and then from N. E. by N., cool, with heavy scud, during +the forenoon, veering gradually to the N. N. E., and dying away. After the +rain ceased, the northern edge of the belt was distinctly visible in the +S. and S. E., its stratus-cloud moving E. N. E., and its scud to the +westward.</p> + +<p>The front of that storm did not pass over us. It was long and narrow. The +wind blew somewhat obliquely inward, along its southern border, to the +eastward, and, in like <ins class="correction" title="original: maner">manner</ins>, to the westward, on its northern border, +but from the N. E. axially along its central portions.</p> + +<p>In the last instance, the wind changed from S. W. to N. E. This, too, is +impossible, according to Mr.<span class="pagenum"><a name="Page_255" id="Page_255">[Pg 255]</a></span> Redfield’s theory. Similar instances, in +summer, and early autumn, are not uncommon. But I shall recur to this in +connection with the different <i>classes</i> of storms.</p> + +<p>Again, the manner in which these S. E. winds co-exist with the N. E., and +become the prevailing wind, toward the close of the storm, is instructive, +and inconsistent with the theory of Mr. Redfield. In the West Indies, the +first effect of the storm is to increase the N. E. trade; the wind then +becomes baffling, but settles in the N. W. or N. N. W., <i>in direct +opposition to the admitted progress of the storm</i>. At this point, or at S. +W., it blows with most force. Sometimes it veers gradually, and sometimes +falls calm, and comes out from the S. W., blowing violently. It ends by +veering to the S. E., following gently the course of the storm. Thus, Mr. +Edwards, in the third volume of his History of Jamaica, as herein before +cited, “<i>all hurricanes begin from the north, veer back to W. N. W., W., +and S. S. W., and when they get round to S. E. the foul weather breaks +up</i>.”</p> + +<p>A short, sudden gale, resembling those of our summer thunder-showers, is +sometimes met with from the S. E.; but the violent hurricanes of any +considerable continuance are, in almost every case, as just stated.</p> + +<p>Now, there is, in our latitudes, an obvious law on the subject, and it is +this:—If the storm is not disproportionately long, northerly and +southerly, there is a general tendency to induce and attract a surface +current, in opposition to the course of the storm on<span class="pagenum"><a name="Page_256" id="Page_256">[Pg 256]</a></span> its front, and +especially its north front. At the same time, there is a tendency to +induce a lateral current on its side, <ins class="correction" title="original: particulary">particularly</ins> the southerly side, and +sometimes its south front: that the latter current is, in the first part +of the storm, above the former; in the middle and latter part, it becomes +the prevailing current at the surface, and the wind changes accordingly, +with or without a calm—that this lateral change sometimes takes place on +either side, but usually occurs on the side where the water is warmest, or +there is, for other and local reasons, a <i>greater susceptibility in the +atmosphere to inductive and attractive influence</i>. Thus, our N. E. storms +very frequently have a southerly current also, drawn from the ocean, south +of us, which forms the middle current, and, in the middle and latter part +of it, becomes the prevailing one. <i>I have seen more than a hundred such +instances, clearly and distinctly marked.</i> Since I have been writing this +chapter, January 29th, 1855, such an instance has occurred. On Sunday, the +28th, the cirro-stratus were all day passing from the S. W. to N. E., and +gradually thickening with light air from the E. N. E., in the afternoon. +During the evening the wind set in <i>violently</i> from the N. E., with a +deluging rain. During the night, and after a brief calm, it changed +suddenly to the southward, and blew in like manner. This morning the storm +was gone, and with it, six inches of hard, frozen icy snow; the trade was +clear, with the exception of here and there a broken, melting piece of +stratus, but scud were still running from the southward, and the wind has +been<span class="pagenum"><a name="Page_257" id="Page_257">[Pg 257]</a></span> from the south, veering to S. W., all day, with sunshine. As I have +before remarked, this middle current is always present, in this locality, +in stratus storms, when there is a heavy fall of rain or snow, although, +when the latter happens, the middle current is sometimes from the +northward; if it be from the southward, it turns the snow first into very +large flakes, and then to rain in our part of the storm.</p> + +<p>Doubtless, the same thing occurs every where. In the West Indies, and +especially over the Leeward Islands, the middle current is most commonly +from the stream of warm water which runs off to the westward into the +Caribbean Sea; as the S. W. moonsoon is from the same current below the +Cape de Verdes. The S. W. winds, which come from those south polar waters, +in the West Indies, appear to be the most violent. But it may be on either +or both sides.</p> + +<p>The hurricane cloud of the West Indies moves confessedly N. W. in most +instances, and undoubtedly it does in all. There is an immutable law that +requires it. The seeming exceptions are not such; they are but instances +imperfectly investigated. Now, a circular storm moving N. W. can set in N. +W. only on the left front, and <i>can not change to S. W. on that side of +the axis</i>. Nor can the wind blow at the axis from N. W. at all. It should +be N. E. in first half, and S. W. in last half. Strange as it may seem, +the axis of a West India hurricane in conformity with Mr. Redfield’s +theory, and a N. W. progression, has never been found, with perhaps a<span class="pagenum"><a name="Page_258" id="Page_258">[Pg 258]</a></span> +single exception, in any one of which I have seen a description. On the +west coast of Europe, the gale is commonly from the Atlantic, either +following under the storm from the S. W., or blowing in diagonally from +the W. or N. W.; the N. E. wind of western Europe being a cold, dry wind, +which there is reason to believe has been around the Siberian pole and is +returning, as the cold northerly winds of the North Pacific have around +the North American magnetic pole. “If the N. E. winds always prevailed,” +says Kämtz, speaking of Berlin, “even at a considerable height it would +never rain.” This was based on an observation of showers, and not fully +reliable. But the dry and cool character of the N. E. wind of western +Europe is unquestionable. The S. E. wind is also a storm wind, but owing +to the character of the surface from which it is attracted, it is not as +violent as the westerly winds are.</p> + +<p>Such, too, is the general course and character of the side wind in the +southern hemisphere. There gales are less frequent, the magnetic intensity +is less, the counter-trades are less; it is not in “the order of +Providence” that as much rain shall fall there. Nevertheless, gales occur, +although rarely, if ever, with equal violence. About New Holland, where +storms are pursuing a S. E. course, they have the wind N. E., +corresponding to our S. E., veering from thence, <i>by the north</i>, to the +westward, clearing off from S. W., with a rising barometer, as ours do +from N. W.</p> + +<p>In the Bay of Bengal, the Indian Ocean, and the Arabian Sea, there is more +irregularity.</p> + +<p><span class="pagenum"><a name="Page_259" id="Page_259">[Pg 259]</a></span>But the law of progress and lateral winds can be distinctly traced as +<i>present</i> and prevailing, notwithstanding the irregularities. Our limits +do not permit an analysis. In the celebrated case of the Charles Heddle, +there was much evidence to show that she was driven across the front of +the storm by one lateral wind, and back by another. (Diagram of Colonel +Reid, p. 206.)</p> + +<p>The waters of the Indian Ocean are hot and confined. Storms there are +often composed of detached masses, move slower—sometimes not more than +three or four miles an hour—and they curve over the ocean, where it is +hotter than in any similar latitude. Yet, notwithstanding all +peculiarities and irregularities, the law we have been considering is +probably the <i>prevailing</i> law there.</p> + +<p>No man knows better the existence of these different currents than Mr. +Redfield. Doubtless it has escaped his attention that the upper of two, +after the passage of a considerable proportion of the storm, becomes the +lower, and causes a seeming change of the same wind.</p> + +<p>In a series of elaborate articles, substantially reviewing the whole +subject, published in the American Journal of Science, for 1846, he says:</p> + +<div class="blockquot"><p>“In nearly all great storms which are accompanied with rain, there +appear two distinct classes of clouds, one of which, comprising the +storm scuds in the active portion of the gale, has already been +noticed. Above this is an extended stratum of stratus cloud, which is +found moving with the general or local current of the lower +atmosphere which overlies the storm. It covers not only the area of +rain, but often extends greatly beyond this limit, over a part of the +dry portion of the storm, partly in a broken or detached state. This<span class="pagenum"><a name="Page_260" id="Page_260">[Pg 260]</a></span> +stratus cloud is often concealed from view by the nimbus, and scud +clouds in the rainy portion of the storm, but by careful +observations, may be sufficiently noticed to determine the general +uniformity of its specific course, and, approximately, its general +elevation.</p> + +<p>“The more usual course of this extended cloud stratum, in the United +States, is from some point in the horizon between S. S. W. and W. S. +W. Its course and velocity do not appear influenced in any +perceptible degree by the activity or direction of the storm-wind +which prevails beneath it. On the posterior or dry side of the gale, +it often disappears before the arrival of the newly condensed cumuli +and cumulo-stratus which not unfrequently float in the colder winds, +on this side of the gale.”</p> + +<p>“The general height of the great stratus cloud which covers a storm, +in those parts of the United States which are near the Atlantic, can +not differ greatly from one mile; and perhaps is oftener below than +above this elevation. This estimate, which is founded on much +observation and comparison, appears to comprise, at the least, the +limit or thickness of the proper storm-wind, which constitutes the +revolving gale.</p> + +<p>“It is not supposed, however, that this disk-like stratum of +revolving wind is of equal height or thickness throughout its extent, +nor that it always reaches near to the main canopy of stratus cloud. +It is probably higher in the more central portions of the gale than +near its borders, in the low latitudes, than in the higher, and may +thin out entirely at the extremes, except in those directions where +it coincides with an ordinary current. Moreover, in large portions of +its area, there may be, and often is, more than one storm-wind +overlying another, and severally pertaining to contiguous storms. In +the present case, we see, from the observations of Professor Snell +and Mr. Herrick, at Amherst, Massachusetts, and at Hamden, Maine (115 +and 135 b.), that the true storm wind, at those places, was +super-imposed on another wind; and various facts and observations may +be adduced to show that brisk winds, of great horizontal extent, are +often limited, vertically to a very thin sheet or stratum.”</p></div> + +<p>Much of the foregoing is graphically described, and unquestionably true. +But it may well be asked how he, or others, distinguish which of two or +more currents (for there are frequently three, and sometimes four +visible), are the true currents of the storm, and which interlopers from +another storm? Is the<span class="pagenum"><a name="Page_261" id="Page_261">[Pg 261]</a></span> true one always the upper one, and why? If the +upper one, why is the interloper at the surface noted and quoted to prove +what a storm is? How does he know what proportions of the winds he has +recorded to show the revolving motion of gales, were the true storm winds +of the particular storm? or, that every one of them was not an interloping +wind on which the true storm wind was superimposed?</p> + +<p>These inquiries are pertinent, for obviously, unless some rule for +distinguishing between the currents is given, and there be evidence of +direct observation to show that the surface wind, whose direction is +noted, is the true wind of the storm, and that the <i>latter</i> is not +<i>superimposed</i>, no reliance can be placed upon logs, or newspaper +accounts, or registers. There is another element besides direction, viz.: +superimposition, a determination of which <i>is</i> essential to <i>truth</i>. It +will be difficult for Mr. Redfield to say that a determination of that +element has been made, with certainty, in a single storm he has +investigated; and in relation to the convergence of storms, and blending, +and superimposition of their winds, I think he is mistaken.</p> + +<p>Mr. Redfield is right in saying (American Journal of Science, vol. ii., +new series, p. 321) that “too much reliance may be placed upon mere +observations of the surface winds in meteorological inquiries,” and yet +<i>they</i> only have thus far been regarded, and he has proved gyration in no +other way. I have frequently, with a vane in sight, asked intelligent men +how the wind was, and been amused and <span class="pagenum"><a name="Page_262" id="Page_262">[Pg 262]</a></span>instructed by their inability to +state it correctly. Mr. Redfield, in his inquiries, often found two +reports of the weather at the <i>same time</i>, from the <i>same place</i>, +materially different; and I have known, from my own observation, +newspapers and meteorological registers to be several points out of the +way; and this, because the vanes are influenced by local elevations, and +change several points, and very often; because few know the exact points +of the compass in their own localities, and because entire accuracy has +not been deemed essential. For these reasons, newspaper and telegraphic +reports are not always reliable; and therefore, and because, also, +storm-winds are easterly and fair winds westerly, and the former veer from +east around to west, on one or both sides in many cases, there are few +storms which can not be represented as whirlwinds, by a proper <i>selection</i> +of <i>reports</i>, a corresponding <i>location</i> of the <i>center</i>, and an +<i>extension</i> of the lines of supposed gyration, so as to include the +<i>preceding</i> winds, the actual winds of the storm, and the <i>lateral</i>, and +<i>succeeding</i> fair weather ones.</p> + +<p>But, again, Mr. Redfield is right in saying there is, in such cases, “an +extended stratum of stratus cloud,” and it is always present. But why does +he say this <i>covers the storm</i>? Is it distinct from it, and if so, what is +it doing there? What power placed it there, and for what purpose? Has this +extended stratum of cloud, which forms the canopy of a vast chamber—five +hundred to one thousand miles in diameter, and less than two miles in +vertical depth, while the earth forms the floor—any agency in producing +the<span class="pagenum"><a name="Page_263" id="Page_263">[Pg 263]</a></span> whirl that is supposed to be going on within it, and if so, what? Has +the earth any agency, and if so, what? If neither the ceiling nor floor of +the chamber have any agency in producing it, what does? Are we to consider +the <i>storm-scud</i> as possessing the power, and as waltzing around the +aerial chamber, carrying the air with them in a hurricane-dance of +devastation? <i>What, in short, is the power, and how is it exerted?</i></p> + +<p>To these questions, Mr. Redfield’s essays furnish no comprehensive answer. +There is an intimation that the cause of storms will be, at some future +day, developed. One attempt, and but one, has thus far been made, and that +I quote entire:</p> + +<div class="blockquot"><p>“We have seen that the two Cuba storms, as well as the Mexican +northers, have appeared to come from the contiguous border of the +Pacific Ocean.</p> + +<p>“Now, are there any peculiarities in the winds and aerial currents of +those regions, which may serve to induce or support a leftwise +rotation in extensive portions of the lower atmosphere, while moving +on, or near the earth’s surface? I apprehend there are such +peculiarities, which have an extensive, constant, and powerful +influence. First, we find on the eastern portion of the Pacific, from +upper California to near the Bay of Panama, an almost constant +prevalence of north-westerly winds at the earth’s surface. Next, we +have an equally constant wind from the southern and south-western +quarter, which, having swept the western coast of South America, +<i>extends across the equator to the vicinity of Panama</i>, thus meeting, +and commonly over-sliding the above-mentioned westerly winds, and +tending to a deflection or rotation of the same, from right to left. +As this influence may thus become extended to the Caribbean or +Honduras Sea, we have, next, the upper or S. E. trade of this sea, +which is here frequently a surface-wind, and must tend to aid and +quicken the gyrative movement, ascribed to the two previous winds; +and lastly we have the N. E. or lower trade, from the tropic, which, +coinciding with the northern front of the gyration, serves still +further to promote the revolving movement which may thus result from +the partial coalescence<span class="pagenum"><a name="Page_264" id="Page_264">[Pg 264]</a></span> of these great winds of Central America, and +the contiguous seas.</p> + +<p>“Thus, while a great storm is, in part, on the Pacific Ocean, its N. +E. wind may be felt in great force on that side of the continent, +through the great gorges or depressions near the bays of Papagayo or +Tehuantepec, as noticed by Humboldt, Captain Basil Hall, and others, +the elevations which there separate the two seas being but +inconsiderable; and, when the gyration is once perfected, the whole +mass will gradually assume the movement of the predominant current, +which is generally the higher one, and will move off with it, +integrally, as we see in the cases of the vortices, which are +successively found in particular portions of a stream, where subject +to disturbing influences.”</p></div> + +<p>The analogy between this and the theory of Professor Dove, cited above, +and prior, in point of time, is obvious. They are substantially alike in +principle, with different locations. They differ also in this, Professor +Dove appears to think something more than over-sliding necessary, and +assigns the duty of crowding the upper current down in to the lower, to +make an <i>encounter</i>, to a lateral overflow from Africa. Mr. Redfield seems +to think there may be a tendency to deflection when they “over-slide” each +other. They are both closet hypotheses, the poetry of meteorology, with +something more than poetical license as to facts.</p> + +<p>In the first place, <i>no such concurring winds exist in the same locality +at the same time</i>. When the inter-tropical belt of rains is over Central +America and Southern Mexico, a S. W. monsoon blows in under it, but it +usurps the place of all other surface winds; and, when the belt is absent, +that portion of the eastern Pacific is most remarkably calm, or is covered +by the N. E. trades. Secondly, the <i>trade-winds every where pursue their +appointed course without “tendency<span class="pagenum"><a name="Page_265" id="Page_265">[Pg 265]</a></span> to deflection” by the meeting, or +“over-sliding,” or “breaking in,” or “encounter,”</i> of other winds. The +great laws of circulation do not admit of any such <i>confusion</i>. And, +lastly, <i>no storm ever came over the eastern United States from that +quarter</i>. The unchangeable laws of atmospheric circulation forbid it. +Recent observations also have shown that the storms on the west coast of +Central America, and the eastern Pacific, pursue a N. W. course, precisely +as in the West Indies, and every where over the surface-trades of the +northern hemisphere. Indeed <i>Mr. Redfield himself has recently +investigated several of them, and admits their course to be +north-westerly</i>. (See American Journal of Science, new series, vol. xviii. +p. 181.)</p> + +<p>But, suppose the co-existence of the winds and the course of the storms +admitted as claimed, let us seek for clearer views. What do these +gentlemen mean? Do they intend to have us believe the air has inherent +moving power, and that the “tendency” of which they speak is an attribute +of the winds, and that when they thus meet, and “come into each other,” +“encounter,” or “over-slide,” and become acquainted, they wheel into a +waltz, and move off northward, “integrally,” with unceasing circular +movement, even until they arrive at the Arctic circle? Or is it a mere +mechanical effect of meeting, “coming into each other,” or “over-sliding?” +If the latter, why a tendency to rotation from right to left? The +trade-winds, at least, are <i>continuous, unbroken sheets</i>, and not +disconnected portions which meet and blow past each other, and there is no +warrant for placing them<span class="pagenum"><a name="Page_266" id="Page_266">[Pg 266]</a></span> <i>side and side</i>, and attributing to them any +such mechanical effect, and as little respecting the other winds. Outside +of the fanciful hypothesis, there are no facts to show such a tendency one +way rather than the other; and, in accordance with the known facts +regarding stratification of the currents of air, no such “tendency” can +exist.</p> + +<p>But what <i>power</i> impels the winds, which thus meet at these points? If +they be impelled, is it consistent with the action of this power that the +<i>winds</i> it has <i>created</i> and <i>controls</i>, should thus assume an <i>opposite +“tendency,”</i> and whirl away to the north-eastward, regardless of the power +that originated and controls them? What must this “<i>tendency</i>” be, which +thus <i>occasionally</i> not only diverts the winds from the <i>usually regular +course</i> given them by their originating power, but increases their action, +from gentle, ordinary winds, to hurricanes? Nay, which gives them a new, +resistless gyratory and electric energy, increasing as the new, +independent, supposed cyclonic organization moves off, “<i>integrally</i>,” +away from “the home of its many fathers,” on a devastating journey towards +the north pole?</p> + +<p>And, further, if all this were true as to the West Indies and Central +America, what is to be said of the billions of other storms, originating +on a thousand other portions of the earth’s surface, and how are they to +be accounted for, inasmuch as such other “meetings,” “coming into each +other,” and “over-sliding,” and “tendency to deflection,” is not assumed +to exist?</p> + +<p><span class="pagenum"><a name="Page_267" id="Page_267">[Pg 267]</a></span>These questions cannot be satisfactorily answered. The distinguished +theorists are mistaken. The stratus-cloud does not over-lie or cover the +storm. <span class="smcap">It is the storm.</span> The winds beneath, whether surface or +superimposed, are but its incidents, due to its static induction and +attraction. Their <i>direction</i> depends on the shape of the storm cloud, and +its course of progression, and the susceptibility of the surface +atmosphere in this direction or that, to its inductive and attractive +influence. Their <i>force</i> to its depth, its contiguity to the earth, and +the intensity of its action; and the scud, are but patches of +condensation, occasioned by the same inductive action which affects and +attracts the surface current in which they form.</p> + +<p>Another objection to Mr. Redfield’s theory of gyration is based upon the +fact that in order to constitute his <i>storm</i>, to get the <i>gyration</i>, he +has to include, at least, an equal amount, generally a great deal more, of +<i>fair weather</i>. The N. W. wind, the “posterior, or dry side of the gale,” +as he calls it (in the foregoing extract), is a <i>fair weather wind</i>. It is +<i>necessary</i>, however, to complete the supposed <i>circle</i>, and it is +<i>pressed into the service</i>. The practical answer given to the question, +“<i>what are storms?</i>” is, they are cyclones, part storm, so called, and +<i>part fair weather</i>; that is, the stratus-cloud, the scud, the easterly +wind, and rain or snow of day before yesterday, were the <i>wet side</i>, or +front part of the storm, and the sunshine, clear sky, and N. W. wind of +yesterday, to-day, and, perhaps, to-morrow, are the posterior or dry side. +When a storm clears off from the N. W. it is not<span class="pagenum"><a name="Page_268" id="Page_268">[Pg 268]</a></span> <i>over</i>, it is, perhaps, +<i>just begun</i>; and, inasmuch as it storms again, very soon after the wind +changes back from the N. W. to the southward, in winter, our weather then +is pretty much all <i>storms</i>.</p> + +<p>The statement of this claim seems so absurd that it may appear like +injustice to make it. But gyration can not be made out without it, and it +is evident in the extract quoted above; in the claim that the winter +northers of the Mexican Gulf are parts of passing storms; and clearly and +unequivocally advanced as a distinct proposition, as follows:</p> + +<p>“1. The body of the gale usually comprises an area of rain or foul +weather, together with another, and, perhaps equal, or greater, area of +fair or bright weather.” (Am. Jour. of Science, vol. xlii. p. 114.)</p> + +<p>Now, in the first place, we must distinguish between a storm and fair +weather, before we can tell what the former is, and it is difficult to +assent to a theory which explains what a S. E. storm of <i>twelve hours’</i> +continuance is, by including <i>two or three days of succeeding N. W. fair +weather wind</i>, as a part of it. There is no proportionate relation as to +<i>time</i>, nor any relation as to <i>qualities</i>, or the attending conditions of +the atmosphere, nor any conceivable <i>connection</i>, except the hypothetical +one of <i>gyration</i>, between the two winds.</p> + +<p>And, in the second place, it is true, and Mr. Redfield is well aware of +the fact, that winds often blow for many days from the N. E., S. W., or N. +W., without any preceding or succeeding winds to which they have any +discoverable relation. If, therefore, truth<span class="pagenum"><a name="Page_269" id="Page_269">[Pg 269]</a></span> would justify Mr. Redfield in +including the fair weather wind, a difficulty would remain which his +theory does not cover or explain.</p> + +<p>No American, except Mr. Redfield, has been able to discover satisfactory +evidence of the gyration of storms, by actual careful observation, or a +careful unbiased collation of the observation of others. Professor Coffin +is reported to have read to the Scientific Association, at their Buffalo +meeting, a paper, confirmatory, in part, but I have not been able to see +it. The tracks of tornados have been searched as with candles. When they +have been narrow, from forty to eighty rods, their action has been +substantially similar, and, although, as we have herein before stated, +some irregularities have been found which were consistent with +gyration—for irregularities attend the violent action of all forces, and +particularly the motion of electricity through the atmosphere, as every +one who has seen the zig-zag course of a flash of lightning knows—yet the +evidence of two lateral inward currents, or lines of force, has +predominated over all others. In all cases, where the path is narrow, +those lateral currents are the actors; they constitute the tornado; their +<i>irregularities</i> of action produce the exceptions; but the exceptions are +neither numerous nor uniform, and do not prove either the theory of Mr. +Espy or that of Mr. Redfield. The action is not that of moving air, +merely, but of a power exceeding in force that of powder, which nothing +but electricity or magnetism can exert. As the path widens, the wind +becomes more like the<span class="pagenum"><a name="Page_270" id="Page_270">[Pg 270]</a></span> straight-line gust which follows beneath the +ordinary severe thunder-showers. His theory finds no substantial +confirmation or support in the path of the tornado.</p> + +<p>Several storms were investigated by Professor Espy, some of them the same +which Mr. Redfield had attempted to show were of a rotary character; one +or two by the Franklin Institute of Philadelphia; one by Professor Loomis, +already alluded to; and recently, two by Lieutenant Porter, from logs +returned to the National Observatory. None of these investigations confirm +the theory of Mr. Redfield. Indeed, Mr. Redfield himself has found it +necessary to resort to suppositions of <i>modifying causes</i> to explain the +evident inconsistencies. It is assumed that the axis, or center, +oscillates, and describes a series of circles; and thus, one class of +difficulties is avoided. Again, it is assumed that simultaneous storms +converge and blend upon the same field, and another class of difficulties +are surmounted. And, again, inasmuch as it is notorious that violent gales +are rarely if ever felt with equal violence around the area of a circle, +but from one or two points only, it is assumed, that the storm winds +ascend, superimpose, and descend again, when they return to the place of +their first violent action, etc. The <i>simple truth</i> requires no such +resort to <i>modifying hypothesis</i>.</p> + +<p>Still, another objection is, that the changes in the barometer, which +occur before, during, and after storms, do not sustain the claims of Mr. +Redfield or the requirements of his theory.</p> + +<p><span class="pagenum"><a name="Page_271" id="Page_271">[Pg 271]</a></span>The barometer sometimes rises before storms. It generally commences +falling about the time, or soon after the storm sets in, continues to fall +during its progress, and rises again, sooner or later, afterward. This is +the general rule.</p> + +<p>On this subject Mr. Redfield’s claim is this:</p> + +<div class="blockquot"><p>“<span class="smcap">Effect of the Gale’s Rotation on the Barometer</span>.—The extraordinary +fall of the mercury in the barometer, which takes place in gales or +tempests, has attracted attention since the earliest use of this +instrument by meteorologists. But I am not aware that the principal +cause of this depression had ever been pointed out, previously to my +first publication in this journal, in April, 1831, when I took the +occasion to notice this result as being obviously due to the +<i>centrifugal force</i> of the revolving motion found in the body of the +storm.</p> + +<p>“Since that period, inquiries have been continued by meteorologists +in regard to the periodical and other fluctuations of the barometer, +and the relations of these fluctuations to temperature and aqueous +vapor. But these incidental causes of variation, in the atmospheric +pressure, prove to be of minor influence, and we are left to the +sufficient and only satisfactory solution of this marked phenomenon +which is found in the centrifugal force of rotation.”</p></div> + +<p>The average pressure of the atmosphere, at the surface of the ocean, or in +the interior of the country, allowing for elevation, is about equal to the +weight of a column of quicksilver, thirty inches in height; hence the +barometer is said to stand at about thirty inches at the level of the sea.</p> + +<p>This is sufficiently accurate for the northern hemisphere, north of the N. +E. trades; but the average is somewhat lower in the trades and in the +southern hemisphere. Thus, the average of sixteen months, during which the +Grinnell expedition was absent, was 30.<span style="font-size: 0.8em;"><sup>08</sup></span>⁄<span style="font-size: 0.6em;">100</span>.</p> + +<p><span class="pagenum"><a name="Page_272" id="Page_272">[Pg 272]</a></span>From a large number of logs examined by Lieutenant Maury, the mean +elevation in the N. E. trades of the Atlantic was 29.<span style="font-size: 0.8em;"><sup>97</sup></span>⁄<span style="font-size: 0.6em;">100</span>; the S. E. +trades of the Atlantic, 29.<span style="font-size: 0.8em;"><sup>93</sup></span>⁄<span style="font-size: 0.6em;">100</span>; off Cape Horn, +29.<span style="font-size: 0.8em;"><sup>23</sup></span>⁄<span style="font-size: 0.6em;">100</span>; S. E. trades +of the Pacific, 30.<span style="font-size: 0.8em;"><sup>05</sup></span>⁄<span style="font-size: 0.6em;">100</span>; +N. E. trades of the Pacific, 29.<span style="font-size: 0.8em;"><sup>96</sup></span>⁄<span style="font-size: 0.6em;">100</span>. The +height of the barometer off Cape Horn is not a fair index of the general +elevation of the southern hemisphere, inasmuch as it stands lower there +than at the coast of Patagonia and Chili, or at most, if not all, other +stations in that hemisphere.</p> + +<p>As the barometer is constantly oscillating up and down (irrespective of +its diurnal oscillation), it has no known fair weather standard. The point +of 30 inches is taken only as it is a mean. I have known it to commence +storming when the barometer was at 30.70, and not to fall before it +cleared off, below 30.30. And I have known it to be below 30 for several +days consecutively, with fair weather. In our climate there is no reliable +fair weather standard for the barometer. It falls below 30 without +storming; it rises far above, and storms without falling below. No +reliance can be placed upon its elevation, except by comparison; but of +that hereafter.</p> + +<p>The general rule, nevertheless, is, that it falls more or less during +storms, whatever its height, and rises sooner or later, more or less, +after they clear off.</p> + +<p>The difference between its highest and lowest points is called its range. +The greatest range observed, and recorded, is about 3 inches—from about +28 to 31—but this range is rare. The range, in the trade-wind region, is +comparatively small; in this country it<span class="pagenum"><a name="Page_273" id="Page_273">[Pg 273]</a></span> is greater than in Europe; and, +generally, the range will be found greatest where the volume of +counter-trade, and magnetic intensity, and the corresponding amount of +precipitation, and extremes of heat and cold are greatest. One of the +greatest ranges during one storm, or two successive portions of a storm, +in this country, which I have seen recorded, occurred at Boston, in +February, 1842. It was as follows—counting the hours as 24, and from +midnight:</p> + +<table border="0" cellpadding="0" cellspacing="5" summary="boston"> +<tr><td>Feb.</td><td>15..10h..30.36.</td></tr> +<tr><td align="center">"</td><td>16..13h..28.47 fall of 1.89 in 27 hours.</td></tr> +<tr><td align="center">"</td><td>17..19h..30.39 rise of 1.92 in 30 hours.</td></tr> +<tr><td align="center">"</td><td>18.. 2h..30.39 stationary<span class="spacer"> </span>5 hours.</td></tr> +<tr><td align="center">"</td><td>19.. 2h..29.46 fall of 0.93 in 24 hours.</td></tr> +<tr><td align="center">"</td><td>20.. 2h..30.43 rise of 0.97 in 24 hours.</td></tr> +<tr><td> </td><td>Amount of oscillation, 5.71 in 4 days, 11 hours.</td></tr></table> + +<p>These ranges were owing to the alternation of S. E. storms, and N. W. +winds.</p> + +<p>Taking the first range as a basis, and allowing the height of the +atmosphere to be 1,100 feet for the first inch, we have nearly 2,000 feet +displaced during one day, if we look for the displacement near the earth, +or some 30 or 35 miles, if we soar aloft in the upper regions to look for +the <i>lateral overflow</i> of Professor Dove, and about the same quantity +restored the next. This brings us to the inquiry, how was it done? It is +perfectly idle to talk about <i>difference</i> of <i>temperature</i> or <i>tension</i> of +<i>vapor</i>, the <i>ascent</i> of warm air, or <i>descent</i> of cold in a case like +this; or to say that they were occasioned by a lateral overflow of some +thirty miles of its upper portion, first this way and then that, in such a +brief space of time. The change<span class="pagenum"><a name="Page_274" id="Page_274">[Pg 274]</a></span> is equal to nearly +<span style="font-size: 0.8em;"><sup>1</sup></span>⁄<span style="font-size: 0.6em;">15</span> of the weight of +the whole atmosphere, and the cause, whatever it was, existed within two +or three miles of the earth. Mr. Redfield’s explanation I give in his own +words, at length:</p> + +<div class="blockquot"><p>“One of the most important deductions which may be drawn from the +facts and explications which are now submitted, is an explanation of +the causes which produce the fall of the barometer on the approach of +a storm. This effect we ascribe to the centrifugal tendency or action +which pertains to all revolving or rotary movements, and which must +operate with great energy and effect upon so extensive a mass of +atmosphere as that which constitutes a storm. Let a cylindrical +vessel, of any considerable magnitude, be partially filled with +water, and let the rotative motion be communicated to the fluid, by +passing a rod repeatedly through its mass, in a circular course. In +conducting this experiment, we shall find that the surface of the +fluid immediately becomes depressed by the centrifugal action, except +on its exterior portions, where, owing merely to the resistance which +is opposed by the sides of the vessel, it will rise above its natural +level, the fluid exhibiting the character of a miniature vortex or +whirlpool. Let this experiment be carefully repeated, by passing the +propelling rod around the exterior of the fluid mass, in continued +contact with the sides of the vessel, thus producing the whole +rotative impulse, by an external force, analagous to that which we +suppose to influence the gyration of storms and hurricanes, and we +shall still find a corresponding result, beautifully modified, +however, by the quiescent properties of the fluid; for, instead of +the deep and rapid vortex before exhibited, we shall have a concave +depression of the surface, of great regularity: and, by the aid of a +few suspended particles, may discover the increased degree of +rotation, which becomes gradually imparted to the more central +portions of the revolving fluid. The last-mentioned result obviates +the objection, which, at the first view, might, perhaps, be +considered as opposed to our main conclusion, grounded on the +supposed equability of rotation, in both the interior and exterior +portions of the revolving body, like that which pertains to a wheel, +or other solid. It is most obvious, however, that all fluid masses +are, in their gyrations, subject to a different law, as is +exemplified in the foregoing experiment; and this difference, or +departure from the law of solids, is doubtless greater in aëriform +fluids than in those of a denser character.</p> + +<p>“The whole experiment serves to demonstrate that such an active +gyration as we have ascribed to storms, and have proved, as we<span class="pagenum"><a name="Page_275" id="Page_275">[Pg 275]</a></span> deem, +to appertain to some, at least, of the more violent class; must +necessarily expand and spread out, <i>by its centrifugal action, the +stratum of atmosphere subject to its influence, and which must, +consequently, become flattened or depressed by this lateral movement, +particularly toward the vortex or center of the storm</i>; lessening +thereby the weight of the incumbent fluid, and producing a consequent +fall of the mercury in the barometrical tube. This effect must +increase, till the gravity of the circumjacent atmosphere, superadded +to that of the storm itself, shall, by its counteracting effect, have +produced an equilibrium in the two forces. Should there be no +overlaying current in the higher regions, moving in a direction +different from that which contains the storm, the rotative effect +may, perhaps, be extended into the region of perpetual congelation, +till the medium becomes too rare to receive its influence. But +whatever may be the limit of this gyration, its effect must be to +<i>depress</i> the <i>cold stratum</i> of the upper atmosphere, particularly +toward the more central portions of the storm; and, by thus bringing +it in contact with the humid stratum of the surface, to produce a +permanent and continuous stratum of clouds, together with a copious +supply of rain, or a deposition of congelated vapor, according to the +state of the temperature prevailing in the lower region.”</p></div> + +<p>The italics in the foregoing extract are mine; and, in relation to it, I +observe:</p> + +<p>1st. There is no cylindrical vessel around storms, and <i>air will not thus +resist air</i>. Confessedly, such resistance is necessary. Let any one watch +his cigar smoke, and see how readily it moves on, with little momentum. +Let any one try the experiment of creating a whirl in the <i>open air</i>, or +in a room, or box of paper, or other material, which can be suddenly +removed, with air colored by smoke. I am exceedingly mistaken if he does +not find the presence of a “cylindrical vessel,” absolutely essential to +prevent the instantaneous tangential escape of the air.</p> + +<p>2d. Turn back to page 3 and look at the fall of the barometer in the polar +regions (recorded in the <span class="pagenum"><a name="Page_276" id="Page_276">[Pg 276]</a></span>extract from Dr. Kane), with <i>scarcely any +wind</i>, and <i>as little variation</i> in its <i>direction</i>, and see how utterly +Mr. Redfield’s theory fails to account for the phenomena.</p> + +<p>3d. If I understand Mr. Redfield correctly, he has abandoned the claim as +originally made, that the wind moves in circles, expanding, and <i>spreading +out</i> by a “<i>lateral movement</i>,” and now asserts that it blows spirally +inward, and elevates the air in the center. I quote:</p> + +<div class="blockquot"><p>“<span class="smcap">Vortical Inclination of the Storm Wind.</span>—By this is meant some +degree of involution from a true circular course. In the New England +storm above referred to, this convergence of the surface-winds +appeared equal to an average of about 6° from a circle. In the +present case, such indication seems more or less apparent in the +arrows on the storm figures of the several charts, where the +concentrical circle afford us means for a just comparison of the +general course of wind which is approximately shown by the several +observations.</p> + +<p>“Perhaps we may estimate the average of the vorticose convergence, as +observed in the entire storm for three successive days, at from 5° to +10°—out of the 90° which would be requisite for a congeries of +<i>centripetal</i> or center-blowing winds. This rough estimate of the +degree of involution is founded only on a bird’s-eye view of the +plotted observations. But, however estimated, this involution seems +to afford a measure of the air and vapor which finds its way to a +<i>higher elevation</i> by means of the vortical movement in the body of +the storm.”</p></div> + +<p>If the elevation of the air at the borders of the storm, and depression in +the middle, resulted from the outward tendency and “lateral movement” of +the revolving air, and from the <i>centrifugal force</i>, as in the experiment +with the water in a cylindrical vessel, as stated in the first paragraph +quoted, an <i>involution</i> of from 5° to 10° from the action of a +<i>centripetal force</i>, must carry the air <i>inward</i>, and the <i>barometer +should<span class="pagenum"><a name="Page_277" id="Page_277">[Pg 277]</a></span> stand highest in the middle of the storm</i>. The change is fatal to +his theory. The two are diametrically opposite in character and effect. In +one, the superior strata would be brought down in the center by the +<i>lateral pressure outward</i>; in the other, they would be elevated by the +<i>involution</i>, which “affords a measure of the air and vapor which finds +its way to a higher elevation,” etc. It is perfectly obvious Mr. Redfield +has refuted his own hypothesis.</p> + +<p>In doing this, he is met by the other difficulty alluded to, which he does +not attempt to explain. This gathering of the air inward, spirally, by a +centripetal force, if it took place, not only would not depress, but <i>must +elevate the barometer in the center, above that of the adjoining +atmosphere</i>.</p> + +<p>When he first attributed the depression of the barometer to a lateral +movement and centrifugal force, he supposed the superior strata descended +into the depression, and their frigidity occasioned the condensation, and +cloud, and rain. How he now proposes to account for the formation of cloud +and rain during storms, while the warm air of the inferior stratum finds +its way to a higher elevation in the center of the storm, he does not +inform us, and we must wait his time.</p> + +<div class="blockquot"><p>“I have,” he says, “long held the proper inquiry to be, <i>what are +storms</i>? and not, <i>how are storms produced</i>? as has been well +expressed by another. It is only when the former of these inquiries +has been solved that we can enter advantageously upon the latter.”</p></div> + +<p>The former does not seem to be yet solved, or the solution of the latter +commenced. Mr. Redfield tells<span class="pagenum"><a name="Page_278" id="Page_278">[Pg 278]</a></span> us (page 259, and onward), that there is an +extended stratum of stratus-cloud, which overlies the storm, and that it +does not differ greatly from one mile in height. We are not told how the +air, which finds its way to a higher elevation during several days +continuance of such a storm, <i>gets through the stratum</i>. If he is right it +<i>must</i> do so, and it would not answer to <i>suppose</i> a very small opening or +gentle current through it, to carry off all the air which works inward in +a hurricane, during several days continuance. But he does not seem to +recognize either the necessity or existence of any <i>vent</i> at all; nor is +there any; and this fact is open to the observation of every school-boy in +the country; and it is equally open to his observation that <i>when and +where the barometer is most depressed, the stratus storm-cloud is nearest +the earth</i>. Colonel Reid has much to say about the “<i>storm’s eye</i>,” or +“treacherous center” of a storm. A careful analysis of the instances where +the “storm’s eye” is noticed will show that the term is applied, in the +northern hemisphere, to that lighting up in the W. or N. W., which is the +commencement of the clearing-off process, and attended with a shift of +wind to the fair-weather quarter: <i>i. e.</i>, to W. or N. W. Just such an +“eye” as is seen when the last of the storm cloud has passed so far to the +east as to admit the rays of the sun under the western or north-western +edge of it. The same kind of “storm’s eye” is described in the southern +hemisphere, except that the wind shifts to S. W. instead of N. W., that +being the clearing-off wind there. No instance of a “<i>storm’s<span class="pagenum"><a name="Page_279" id="Page_279">[Pg 279]</a></span> eye</i>” in +the center of the extended stratum of stratus-cloud, which overlies the +storm, can be found recorded, to my knowledge; and it is obvious that +Colonel Reid adopts the view of Mr. Redfield, that the westerly and N. W. +<i>fair weather</i> winds are a part of the storm. So long as these gentlemen +hold to that opinion they will never solve the question, “<i>what are +storms?</i>” or reach the other, “<i>how are storms produced?</i>”</p> + +<p>Notwithstanding, Mr. Redfield asserts, or adopts the assertion, that the +inquiry should be, “What are storms?” not “How are storms produced?” that +inquiry should be a <i>rational</i> one, and should not violate all analogy, or +call for an explanation which science can not <i>rationally</i> furnish. Mr. +Redfield does not seem to have formed any just conception of the +<i>immeasurable power</i> of a hurricane, <i>five hundred miles in diameter</i>; or +of the nature of that <i>rod</i> which the <i>Almighty must insert in it, to +whirl it with such violent and long-continued force</i>; nor any just +conception of the tendency of the whirling mass, in the absence of his +“cylindrical vessel,” to fly off, tangentially, into the surrounding air; +or of the nature or power of the centripetal force necessary to hold the +gyratory mass in its current, and gather it in involute spirals toward a +center. Nor has any other man who has witnessed, or read of +mountain-tossed waves; of the largest ships blown down and engulfed; of +towns submerged, and vessels carried far inland, and left in cultivated +fields, by the subsidence of the sea; of sturdy forests and strongly-built +edifices prostrated;<span class="pagenum"><a name="Page_280" id="Page_280">[Pg 280]</a></span> or listened to the howling of the tempest, and felt +his own house rock beneath him, been able to conceive of any known form of +calorific or mechanical, or other power, acting from a comparatively small +center, which could hold such an immense irresistable mass of whirling air +in a circle, and <i>gather it</i> in toward the center in gradually contracting +spirals. I confess that, to my mind, it seems little less than a mockery +of our intelligence for Mr. Redfield, or Professor Dove, or any other man, +how distinguished soever he may be, to tell us that all this is the result +of a “tendency to left-wise rotation” of ordinary winds, “coming into each +other,” or “over-sliding,” or “meeting,” or “encountering,” on this +“front,” or that, down in Central America, or in the West Indies, or the +monsoon region; or to talk of “lateral overflows” from mere gravity; of +the ascent of warm air, or the descent of cold strata; of the <i>resistance +of adjacent passive air</i>, or other mere <i>atmospheric resistances</i> in +connection with such <i>awful manifestations of power</i>. Their explanations +of these phenomena are not rational, nor can they be believed by any +rational man, who will bestow upon them half an hour of <i>comprehensive, +unbiased reflection</i>.</p> + +<p>Waiving many minor points of great force, for this notice of Mr. +Redfield’s theory is already too much extended for my limits, I am +constrained to take issue with him on the fact, and to assert, +unhesitatingly, that in a <i>majority of instances no such barometric curve +exists</i>.</p> + +<p>Doubtless the depression beneath the storm is<span class="pagenum"><a name="Page_281" id="Page_281">[Pg 281]</a></span> found, and exterior lateral +elevations may also be had by <i>extending the line into the usual fair +weather elevation on each side</i>, as Mr. Redfield is obliged to do, to get +his supposed circle of winds at all. Doubtless, too, the seamen sailing +out of a storm, on either <i>side</i>, and approaching fair weather, will have +a rising barometer. But from <i>front to rear, on the line of progression</i>, +in tropical storms, the curve does not exist on shore, in this latitude, +oftener than in two, or possibly three, cases in ten; and then only upon a +single state of facts—that is, when there is an interposition of N. W. +wind; and this, at some seasons, rarely occurs. An elevation usually +occurs before the storm, on its front, if it present an extensive easterly +front, as one of these classes does, and a <i>depression is left</i> after it +has passed off, unless a considerable body of N. W. wind interposes, as +heretofore stated. But when there is not such interposition of N. W. wind +(for W., W. N. W., or even N. W. by W. will not suffice), there is not an +immediate rise of the barometer corresponding in rapidity and extent with +the fall, and frequently none during the first twenty-four hours of +bright, fair weather. Let the reader, if he has access to a barometer, +note this fact, for it is obvious and conclusive.</p> + +<p>Finally, there are other atmospheric conditions to which the barometric +changes are obviously due:</p> + +<p>1st. The counter-trade is of a different <i>volume</i>, at different times, +over the same locality, and hence a difference in the normal elevations of +the barometer.</p> + +<p>2d. It is at a different <i>elevation</i>, at different times,<span class="pagenum"><a name="Page_282" id="Page_282">[Pg 282]</a></span> over the same +locality. It was so found by the investigations of the Kew Observatory +Committee referred to; has been so found by other aeronauts, and may +readily be seen by a careful, practiced observer.</p> + +<p>It is highest, with a high barometer, in serene weather, when a storm is +not at hand; and can sometimes be plainly seen to ascend when a +considerable volume of N. W. wind is blowing in beneath, and elevating, +simultaneously, the trade and the barometer.</p> + +<p>Opportunities occur every year, when the northern edge of the dissolving +stratus-cloud is attenuated, and the storm is clearing off in the N. W., +with wind from that quarter, and a rising barometer, when its gradual +elevation may be observed to correspond with the <i>volume</i> of that wind.</p> + +<p>3d. During storms, with a low barometer, the <i>trade</i> and the <i>clouds run +low</i>. This, too, is clearly observable, especially when the stratus-cloud +passes off abruptly, very soon after the rain ceases. In such cases the +barometer will remain depressed for a considerable time, unless another +storm supervenes speedily, or the wind sets in from the N. W.</p> + +<p>4th. The <i>trade, in a stormy state, moves faster</i> than when in a normal +condition. This is observable during the partial breaks which frequently +occur in storms, and at other times. It is also inferable from the more +rapid progress of the more intense center, and other intense portions of +storms, and the consequent greater depression of the barometer, under such +centers or intense portions. (See the storm of Professor Loomis.) It is +obvious, also, from the greater<span class="pagenum"><a name="Page_283" id="Page_283">[Pg 283]</a></span> rapidity of progress attending the more +intense and violent storms which all investigations discloses.</p> + +<p>These simple facts explain all the phenomena:</p> + +<p>1st. The trade stratum is a continuous unbroken sheet, and its descent +must displace a portion of the surface atmosphere. A portion of it is +impelled forward, aiding in the precedent elevation of the barometer, and +a portion is attracted backward, into the space from which a like portion +had been previously attracted by the passing storm cloud, forming the +easterly wind.</p> + +<p>2d. The increased progress of the stormy portion of the counter-trade +occasions an accumulation in front of the storm, and an elevation of the +barometer, and tends also to increase the <i>depression</i> under the spot from +which it moves. The latter is, to some extent, counteracted by the thin +sheets of surface wind which are drawn in under the stratus from the +sides. That which is drawn from the front in successive portions, fills +the space from which like portions had been drawn to the westward, and +left behind in a passive state by the passing storm. Thus, the surface +atmosphere of New England may pass under the entire width of a storm, as a +gale; moving now in puffs with great violence, as it passes beneath +irregular and intense portions of the cloud, and now moderately; and be +left, in a passive state, in Kentucky, occupying the space from which the +atmosphere had been previously drawn by the same storm, <i>in like manner</i>, +on to northern Texas.</p> + +<p>3d. The nearer the stratus-cloud to the earth, the<span class="pagenum"><a name="Page_284" id="Page_284">[Pg 284]</a></span> greater the +displacement of surface atmosphere, the lower the barometer, and, +ordinarily, the more violent the wind. First, because the same intensity, +which, by attraction, brings the trade near the earth, acts with greater +force upon the surface atmosphere; and, secondly, the storm winds, which +are often most rapid beneath the clouds and above the earth, are likely to +be felt with more violence at its surface, where the stratus cloud runs +low, especially at sea.</p> + +<p>I desire to commend all these facts, in relation to the theory of Mr. +Redfield, to the careful attention and observation of those who, although +believers in the theory, are not wedded to it; and who have a sincere +desire to understand the phenomena which are continually, and thus far, +<i>mysteriously</i>, occurring within two or three miles of us, while our +knowledge of the distant worlds around us—the science of astronomy—seems +almost perfect.</p> + +<p>I will return to a further and a careful consideration of the nature of +the reciprocal action between the earth and the counter-trade, and the +facts bearing upon the question, in another chapter. It is obvious that +received theories can not aid us materially in the inquiry.</p> + + +<p> </p><p> </p> +<hr style="width: 50%;" /> +<p><span class="pagenum"><a name="Page_285" id="Page_285">[Pg 285]</a></span></p> +<h2><a name="CHAPTER_X" id="CHAPTER_X"></a>CHAPTER X.</h2> + +<p>We are yet ignorant of the true nature of magnetism. We trace its lines, +as in the diagrams, upon and around the magnet; but we can only do this +with soft iron, or other substance, in which magnetic action may be +induced. We know that these lines are currents, or lines of force, for +that force produces sensible effects, and we measure it by the movements +of the needle. We know that these lines may be <i>deflected</i> by other +magnetic bodies, and concentrated upon them. We know that the earth, and +the smallest magnets, exhibit properties in common. The poles of the +magnet are some distance from its extreme ends—so are those of the earth. +The intensity increases, from the center, or near it, to the poles of the +magnet, as shown by its attraction; and the same increase of magnetic +intensity, from the magnetic equator to the magnetic poles, or near them, +is traced upon the earth.</p> + +<p>We know that there are two lines, or rather <i>areas</i>, of greater intensity +upon the globe. One extending from the American magnetic pole, +south-eastwardly, to a corresponding pole in the southern hemisphere; and +another, the Asiatic, extending from the Siberian pole to a corresponding +southern one, in like manner.<span class="pagenum"><a name="Page_286" id="Page_286">[Pg 286]</a></span> We know that, from those lines or areas, +the intensity, east and west, on the same parallel of latitude, decreases +each way, to about midway between them. Thus, calling the intensity where +Humboldt found the magnetic equator over South America, in 7° 1′ south +latitude, 1, or unity—the least intensity known is, .706, found at the +magnetic equator, over the South Atlantic, and at its most southern +depression; and it increases to 1.4 in the West Indies, and to 2.0099 upon +one or more points of the North American continent, south of the magnetic +pole, and about the meridian of 92°. That it is 1.805, at Warren, Ohio, in +latitude 41° 16′, and longitude 72° 57′, and decreases to 1.774 at New +Haven, Connecticut, in latitude 41° 18′. That it is but 1.348 at Paris, +nearly one third less than on the same latitude in some portions of this +continent. That the line of equal intensity, or “<i>iso-dynamic</i>” line, of +1<span style="font-size: 0.8em;"><sup>8</sup></span>⁄<span style="font-size: 0.6em;">10</span>, is a closed curve of an oval shape, extending somewhat below 40°, +in the longitude of Cincinnati, and reaches off nearly to Bhering’s +Straits, on the west; rising in a similar manner, though not so abruptly, +on the east; including the great northern lakes and a considerable part of +Hudson’s Bay. While the iso-dynamic lines of 1<span style="font-size: 0.8em;"><sup>85</sup></span>⁄<span style="font-size: 0.6em;">100</span>, +and 1<span style="font-size: 0.8em;"><sup>875</sup></span>⁄<span style="font-size: 0.6em;">1000</span>, are +smaller ovals, included within the former. Such, at least, is the present +belief from such investigations as have been made. (See an article by +Professor Loomis, American Journal of Science, new series, vol. iv. p. +192.)</p> + +<p>Our subject demands a still closer examination of<span class="pagenum"><a name="Page_287" id="Page_287">[Pg 287]</a></span> the elements of +magnetism and its associated electricities, and their influence upon +climate and the atmosphere with a view to the solution of the questions in +hand, and we will pursue the inquiry in the present chapter.</p> + +<p>Waiving, for the present, any further notice of the fact that the +counter-trades are concentrated over, and contiguous to, this area of +intensity, for the purpose of examining the magnetic phenomena +independently, and intending to return to a consideration of their +connection with it, we observe:—That it is now well settled that the +iso-geothermal lines, or lines of equal terrestrial heat, are coincident, +or nearly so, with the lines of equal magnetic intensity. The points where +the magnetic intensity is at a minimum, on the magnetic meridian, are the +warmest points of that meridian, and those where it is most intense, the +coldest.</p> + +<p>The magnetic elements of a place may be computed from its thermal ones. +The laws producing or governing the distribution of one, have an intimate +physical relation with those producing or governing the other. Professor +Norton ably sums up a discussion of the subject (in the American Journal +of Science for September, 1847), omitting the theoretic propositions, as +follows:</p> + +<div class="blockquot"><p>“1. All the magnetic elements of any place on the earth may be +deduced from the thermal elements of the same; and all the great +features of the distribution of the earth’s magnetism may be +theoretically derived from certain prominent features in the +distribution of its heat.</p> + +<p>“2. Of the magnetic elements, the horizontal intensity is nearly<span class="pagenum"><a name="Page_288" id="Page_288">[Pg 288]</a></span> +proportional to the mean temperature, as measured by Fahrenheit’s +thermometer; the vertical intensity is nearly proportional to the +difference between the mean temperatures, at two points situated at +equal distances north and south of the place, in a direction +perpendicular to the iso-geothermal line; and, in general, the +direction of the needle is nearly at right angles to the +iso-geothermal line, while the precise course of the inflected line +to which it is perpendicular may be deduced from Brewster’s formula +for the temperature, by differentiating and putting the differential +equal to zero.</p> + +<p>“3. As a consequence, the laws of the terrestrial distribution of the +physical principles of magnetism and heat must be the same, or nearly +the same; and these principles themselves must have, toward one +another, the most intimate physical relations.”</p></div> + +<p>The magnetic elements, of which Professor Norton speaks, are the +declination, dip, and horizontal and vertical forces or intensities.</p> + +<p>I have said, that toward the areas of greatest magnetic intensity, the +needle every where declines. So as intensity increases, from the magnetic +equator toward the poles, the needle, when so suspended as to permit of +the motion, <i>dips</i>, inclines downward, and the dip is greatest, on the +same parallel, where intensity is greatest. To my mind, the magnetic +elements <ins class="correction" title="original: are are">are</ins> very intelligible. They are all attributable to attraction, +and attraction is greatest where intensity is greatest. There is nothing +in the earth or atmosphere to make the needle point northerly rather than +in any other direction, except magnetic intensity. Thus, the greater +intensity of magnetism near the northern and southern points of the globe, +attracts the corresponding ends of the needle in those directions. And, as +magnetism increases in quantity or intensity, and the poles are +approached, the attraction increases, and the needle dips more<span class="pagenum"><a name="Page_289" id="Page_289">[Pg 289]</a></span> and more, +till the focus of intensity and attraction is reached, and then it becomes +perpendicular. So magnetism is unequally diffused, meridionally, in or +over the earth, and there are two equidistant areas where its quantity or +intensity is greatest. These exert a lateral attraction upon the needle; +it yields to this attraction, and hence its declination. If it is carried +on to one area of intensity, and to the center of it, it will point to the +northern focus of intensity or magnetic pole; and, if carried a trifle +further west, it will yield to an eastern attraction, and point directly +north. If carried still further west, its declination <i>east</i> will +increase. Thus its normal direction is to the pole, on the central focus +of intensity, and when it points directly north it is west of the central +line of intensity. And thus, it seems to me, all the magnetic elements may +be resolved into the one element of attraction by excess of intensity or +activity.</p> + +<p>This impression is strengthened by the fact that the needle moves to the +east in the morning, when the solar rays increase magnetic activity in +that direction, and west again, as their influence increases there.</p> + +<p>Now, these elements—the declination and horizontal and vertical +forces—all these periodical, regular, and irregular variations of +magnetic activity, are intimately connected with the variations of +atmospheric condition:</p> + +<p>First, They show an increase of activity during certain hours of the day, +corresponding to, and obviously connected with, the diurnal atmospheric +changes.</p> + +<p><span class="pagenum"><a name="Page_290" id="Page_290">[Pg 290]</a></span>Second, They show an increase of activity during the northern transit of +the atmospheric machinery—an <i>annual</i> variation.</p> + +<p>Third, They show an increase in that activity during the latter portion of +each decennial period, conforming to the occurrence of solar spots.</p> + +<p>And, fourth, <i>Irregular variations</i> of activity, corresponding with the +<i>irregular changes</i> of atmospheric condition.</p> + +<p>We will examine these results, and in doing so, take those of the element +of declination—one answering for all.</p> + +<p>The magnetic needle moves to the west in summer, from about 8 <span class="smcaplc">A.M.</span> till +about 2 <span class="smcaplc">P.M.</span>, and the extent of its progress, during that period, +constitutes the magnitude of its daily variation. It is found that this +variation differs in different months, and that it is normally greatest in +the summer months, and least in the winter, in the ratio of about two to +one. It is further found, that in different years the maximum activity +occurs in different months, and that the years differ also, and there is a +distinctly marked decennial period, corresponding most remarkably with the +decennial maxima of recurring solar spots, as observed by Schwabe. Dr. +Lamont, of Munich, gives us the following table of magnitude of +declination there, for the ten years preceding 1851, which clearly +exhibits this fact, and also the greater intensity during the northern +transit of the atmospheric machinery. He says:</p> + +<div class="blockquot"><p><span class="pagenum"><a name="Page_291" id="Page_291">[Pg 291]</a></span>“The magnitude of the variations of declination have a period of ten +years. For five years there is a uniform increase, and during the +following five years a uniform decrease in the variations. With us +the magnetic declination is a minimum at about eight o’clock in the +morning, and is greatest at two o’clock in the afternoon. Subtracting +the declination at eight o’clock from that at two o’clock, we obtain +<i>the magnitude of the diurnal motion</i>. From the hourly observations, +conducted in this observatory since the month of August, 1840, we +ascertain the following to be the magnitude of the diurnal motion for +each month separately.”</p></div> + +<table border="0" cellpadding="0" cellspacing="0" summary="observations"> +<tr><td class="btrl"> </td> + <td class="btr"><small>Jan.</small></td> + <td class="btr"><small>Feb.</small></td> + <td class="btr"><small>March.</small></td> + <td class="btr"><small>April.</small></td> + <td class="btr"><small>May.</small></td> + <td class="btr"><small>June.</small></td> + <td class="btr"><small>July.</small></td> + <td class="btr"><small>Aug.</small></td> + <td class="btr"><small>Sept.</small></td> + <td class="btr"><small>Oct.</small></td> + <td class="btr"><small>Nov.</small></td> + <td class="btr"><small>Dec.</small></td> + <td class="btr" align="center"><small>Autmn & Wint.</small></td> + <td class="btr" align="center"><small>Spring & Sum.</small></td> + <td class="btr"><small>Year.</small></td></tr> +<tr><td class="btrl">1841</td> + <td class="btr">3.72</td> + <td class="btr">5.13</td> + <td class="btr"><span style="margin-left: .5em;">8.43</span></td> + <td class="btr">11.49</td> + <td class="btr">11.47</td> + <td class="btr">11.49</td> + <td class="btr">10.07</td> + <td class="btr"><span style="margin-left: .5em;">9.86</span></td> + <td class="btr"><span style="margin-left: .5em;">8.78</span></td> + <td class="btr"><span style="margin-left: .5em;">6.82</span></td> + <td class="btr">3.71</td> + <td class="btr">2.89</td> + <td class="btr" align="center">5.12</td> + <td class="btr">10.53</td> + <td class="btr"><span style="margin-left: .5em;">7.82</span></td></tr> +<tr><td class="blr">1842</td> + <td class="br">3.65</td> + <td class="br">4.74</td> + <td class="br"><span style="margin-left: .5em;">8.34</span></td> + <td class="br">10.33</td> + <td class="br"><span style="margin-left: .5em;">9.31</span></td> + <td class="br"><span style="margin-left: .5em;">9.78</span></td> + <td class="br"><span style="margin-left: .5em;">8.38</span></td> + <td class="br"><span style="margin-left: .5em;">9.03</span></td> + <td class="br"><span style="margin-left: .5em;">7.72</span></td> + <td class="br"><span style="margin-left: .5em;">7.05</span></td> + <td class="br">3.86</td> + <td class="br">2.81</td> + <td class="br" align="center">5.07</td> + <td class="br"><span style="margin-left: .5em;">9.09</span></td> + <td class="br"><span style="margin-left: .5em;">7.03</span></td></tr> +<tr><td class="blr">1843</td> + <td class="br">3.82</td> + <td class="br">4.08</td> + <td class="br"><span style="margin-left: .5em;">6.87</span></td> + <td class="br"><span style="margin-left: .5em;">9.71</span></td> + <td class="br"><span style="margin-left: .5em;">9.24</span></td> + <td class="br">10.14</td> + <td class="br"><span style="margin-left: .5em;">9.57</span></td> + <td class="br">10.08</td> + <td class="br"><span style="margin-left: .5em;">8.81</span></td> + <td class="br"><span style="margin-left: .5em;">6.82</span></td> + <td class="br">3.82</td> + <td class="br">2.79</td> + <td class="br" align="center">4.70</td> + <td class="br"><span style="margin-left: .5em;">9.59</span></td> + <td class="br"><span style="margin-left: .5em;">7.15</span></td></tr> +<tr><td class="blr">1844</td> + <td class="br">2.81</td> + <td class="br">3.43</td> + <td class="br"><span style="margin-left: .5em;">6.95</span></td> + <td class="br"><span style="margin-left: .5em;">9.53</span></td> + <td class="br"><span style="margin-left: .5em;">8.42</span></td> + <td class="br"><span style="margin-left: .5em;">8.88</span></td> + <td class="br"><span style="margin-left: .5em;">8.38</span></td> + <td class="br"><span style="margin-left: .5em;">9.28</span></td> + <td class="br"><span style="margin-left: .5em;">8.23</span></td> + <td class="br"><span style="margin-left: .5em;">6.54</span></td> + <td class="br">3.94</td> + <td class="br">2.98</td> + <td class="br" align="center">4.44</td> + <td class="br"><span style="margin-left: .5em;">8.79</span></td> + <td class="br"><span style="margin-left: .5em;">6.61</span></td></tr> +<tr><td class="blr">1845</td> + <td class="br">2.20</td> + <td class="br">4.69</td> + <td class="br"><span style="margin-left: .5em;">8.26</span></td> + <td class="br">11.93</td> + <td class="br">10.88</td> + <td class="br">10.73</td> + <td class="br"><span style="margin-left: .5em;">9.44</span></td> + <td class="br">10.42</td> + <td class="br"><span style="margin-left: .5em;">8.82</span></td> + <td class="br"><span style="margin-left: .5em;">7.34</span></td> + <td class="br">4.49</td> + <td class="br">8.34</td> + <td class="br" align="center">5.89</td> + <td class="br">10.87</td> + <td class="br"><span style="margin-left: .5em;">8.13</span></td></tr> +<tr><td class="blr">1846</td> + <td class="br">3.30</td> + <td class="br">6.94</td> + <td class="br"><span style="margin-left: .5em;">9.53</span></td> + <td class="br">12.27</td> + <td class="br">12.58</td> + <td class="br">11.21</td> + <td class="br">11.37</td> + <td class="br">11.49</td> + <td class="br">10.39</td> + <td class="br"><span style="margin-left: .5em;">7.82</span></td> + <td class="br">5.66</td> + <td class="br">3.22</td> + <td class="br" align="center">6.08</td> + <td class="br">11.25</td> + <td class="br"><span style="margin-left: .5em;">8.81</span></td></tr> +<tr><td class="blr">1847</td> + <td class="br">3.30</td> + <td class="br">6.35</td> + <td class="br"><span style="margin-left: .5em;">9.85</span></td> + <td class="br">12.43</td> + <td class="br">11.81</td> + <td class="br">11.76</td> + <td class="br">10.94</td> + <td class="br">12.87</td> + <td class="br">12.06</td> + <td class="br">11.53</td> + <td class="br">7.06</td> + <td class="br">4.70</td> + <td class="br" align="center">7.63</td> + <td class="br">11.98</td> + <td class="br"><span style="margin-left: .5em;">9.55</span></td></tr> +<tr><td class="blr">1848</td> + <td class="br">6.52</td> + <td class="br">9.01</td> + <td class="br">11.96</td> + <td class="br">14.56</td> + <td class="br">14.22</td> + <td class="br">13.80</td> + <td class="br">14.67</td> + <td class="br">15.40</td> + <td class="br">14.00</td> + <td class="br">10.30</td> + <td class="br">5.78</td> + <td class="br">3.53</td> + <td class="br" align="center">7.85</td> + <td class="br"><span style="margin-left: .5em;">4.44</span></td> + <td class="br">11.05</td></tr> +<tr><td class="blr">1849</td> + <td class="br">7.27</td> + <td class="br">8.42</td> + <td class="br">14.08</td> + <td class="br">16.86</td> + <td class="br">13.67</td> + <td class="br">13.86</td> + <td class="br">12.57</td> + <td class="br">11.54</td> + <td class="br">10.79</td> + <td class="br"><span style="margin-left: .5em;">9.12</span></td> + <td class="br">5.41</td> + <td class="br">4.09</td> + <td class="br" align="center">8.06</td> + <td class="br">13.21</td> + <td class="br">10.64</td></tr> +<tr><td class="bblr">1850</td> + <td class="bbr">5.98</td> + <td class="bbr">8.84</td> + <td class="bbr">12.15</td> + <td class="bbr">14.32</td> + <td class="bbr">14.05</td> + <td class="bbr">13.39</td> + <td class="bbr">12.53</td> + <td class="bbr">12.68</td> + <td class="bbr">12.64</td> + <td class="bbr"><span style="margin-left: .5em;">9.04</span></td> + <td class="bbr">6.20</td> + <td class="bbr">3.45</td> + <td class="bbr" align="center">7.61</td> + <td class="bbr">13.27</td> + <td class="bbr">10.44</td></tr></table> + +<p>The Philadelphia and Toronto observations disclose the same state of +facts.</p> + +<p>Dr. Lamont, also, in his article, gives us the following table of the +magnitude of the variations derived from observations at Gottingen:</p> + +<table border="0" cellpadding="0" cellspacing="0" summary="observations"> +<tr><td class="btrl">Year.</td><td class="btr">Mean of Year.</td></tr> +<tr><td class="btrl">1835</td><td class="btr" align="center"><span style="margin-left: .5em;">9.57</span></td></tr> +<tr><td class="blr">1836</td><td class="br" align="center">12.34</td></tr> +<tr><td class="blr">1837</td><td class="br" align="center">12.27</td></tr> +<tr><td class="blr">1838</td><td class="br" align="center">12.79</td></tr> +<tr><td class="blr">1839</td><td class="br" align="center">11.03</td></tr> +<tr><td class="blr">1840</td><td class="br" align="center"><span style="margin-left: .5em;">9.91</span></td></tr> +<tr><td class="bblr">1841</td><td class="bbr" align="center"><span style="margin-left: .5em;">8.70</span></td></tr></table> + +<p>A comparison of these tables, and particularly the latter, with Schwabe’s +table of spots, is interesting.<span class="pagenum"><a name="Page_292" id="Page_292">[Pg 292]</a></span> There is obviously a greater mean +variation when the spots are most numerous. Comparing the two with the +tables of Hildreth, in relation to the temperature, from 1830 to 1840, +there is, to say the least, a most remarkable coincidence. And there are +others equally remarkable.</p> + +<p>There are also irregularities of action disclosed by all, in different +months of the different years, and of the same year, which are obviously +connected with the difference of the seasons; and there are constantly +occurring irregularities and disturbances which correspond with the, as +constantly occurring, irregular atmospheric phenomena. A wide field is +here opened for investigation and research. I have not time or opportunity +to pursue it. Enough appears, so far as I have examined, to confirm the +belief that magnetism is actively concerned in the production of the +varied changes, as well as the normal conditions of the weather.</p> + +<p>In what manner does it act? An answer to this requires an extension of the +inquiry. The lines of magnetic force are every instant passing upward from +the earth, <i>around</i> and <i>through</i> us. Their connection with heat is +unquestionable. They are intimately associated, also, with another equally +obvious and intensely active agent—electricity. We speak of this as an +independent, imponderable, elementary body, but how little we yet know of +it. It is every where, in every thing, easily excited into action, and +then traceable to a certain, but limited extent. It is set in motion, and +becomes obvious to us, by the<span class="pagenum"><a name="Page_293" id="Page_293">[Pg 293]</a></span> chemical action of the acids and metals of +a galvanic apparatus. We separate it from the atmosphere by friction and +excitation, upon non-conductors, as in the electric machine; by the +cleavage of crystals and other exciting operations. We obtain it from +magnets, by the magneto-electric machine, and from the lines of magnetic +force which are ever passing into the atmosphere from the earth, by +intersecting them with a movable iron wire, properly insulated. <i>From the +current of magnetism which has passed through us from the earth, +electricity may thus be separated and collected over our heads.</i> We set it +in motion, and obtain it <i>by heating</i> different metals in connection, or +the same metal unequally; and from certain animals—like the torpedo and +the gymnotus—whose organization is such as to enable them to evolve it. +In all these cases, and they constitute an epitome of the principal +methods by which we obtain it in a distinct form, it is made to flow in +currents. When thus obtained, and imprisoned in non-conductors, it may be +discharged, and with somewhat different effect, as it is discharged in a +mass, disruptively, as it is called, as from the clouds in lightning, or +permitted to flow convectively, in currents, along the wires of a galvanic +apparatus, or in heated air, as from the earth to a cloud in the tornado.</p> + +<p>It is, moreover, capable of division into positive and negative, and when +concentrated or disturbed in one body, it tends to create a similar +disturbance or division in a contiguous mass. To this action of +electricity, the term static induction is applied. Thus,<span class="pagenum"><a name="Page_294" id="Page_294">[Pg 294]</a></span> a positively +electrified body <i>induces</i> a division of the electricity in a contiguous +body, if both are insulated or surrounded by a non-conducting medium; the +negative electricity of the contiguous body being attracted by, and +tending to pass to, the positive of the adjoining body, and the positive +being repelled to the opposite side. That, in its turn, if sufficiently +powerful, tends to disturb the electricity of its neighbor, and attract +away its negative electricity; or, if the body which contains it is free +to move, to attract that. Thus, by the conflicting action of a positive +atmosphere, and a negative earth, and perhaps counter-trade, influenced by +magnetism and the solar rays, the currents and winds of the atmosphere are +produced, the atmosphere moving with exceeding ease and rapidity. +Electricity, excited into currents, or obtained and discharged in either +of the methods enumerated, is identical in character, and produces certain +well-known effects:</p> + +<p>1st. Physiological.—Shocking and convulsing the animal system; producing +a peculiar sensation on the tongue, and a flash before the eyes, and in +sufficient quantity destroying life.</p> + +<p>2d. Magnetic.—<i>Deflecting the needle</i>, and, by a suitable arrangement of +wire into helices, <i>conferring magnetic power</i>, or constituting magnets.</p> + +<p>3d. Luminous.—Producing light—by a spark, as it does in natural +phenomena—by the glow, the brush discharge, the ball of flame, the flash, +or the chain of lightning, and probably the aurora.</p> + +<p>4th. Evolving heat.—Melting metallic substances<span class="pagenum"><a name="Page_295" id="Page_295">[Pg 295]</a></span> by concentration, with a +great intensity of heat—as the wire of the galvanic apparatus, and as is +sometimes seen in the effects of lightning in fusing metals on persons +stricken; and setting combustibles on fire.</p> + +<p>5th. Attraction and repulsion.—Attraction, when the currents flow +parallel with each other, or are of opposite natures, and repelling when +of like character.</p> + +<p>6th. Induction.—Inducing attendant circular or other secondary currents, +such as may be seen in the atmosphere during its most violent displays of +active energy.</p> + +<p>7th. Capable of being dissipated by heated air, or carried off by +moisture, although isolated by dry air, of ordinary temperature, which is +a bad conductor.</p> + +<p>Now, although magnetism can not be collected, imprisoned, or discharged, +like electricity, or collected at all, but by its adherence to some +substance capable of magnetization, it is obvious there is an intimate +association, at least, between it and electricity. <i>They are never found +alone.</i> All <i>electricity</i> will <i>magnetize</i>. All <i>magnetism</i> will evolve +electricity. All <i>currents</i> of <i>electricity</i> have <i>encircling currents</i> of +<i>magnetism</i>, and all deflect the magnetic needle. All magnetic currents +give out to intersecting wires, <i>currents of electricity</i>, and all magnets +<i>induce</i> them.</p> + +<p>Electricity, therefore, whether identical in substance with magnetism, but +differing in form, or whether merely associated with it, as is variously +believed, should be present with magnetism in greater quantity or +intensity where magnetism is most intense, and active, and whenever +present, should be<span class="pagenum"><a name="Page_296" id="Page_296">[Pg 296]</a></span> active and influential. And so we find, from +observation, the fact to be. No inconsiderable effort has been made by the +advocates of the caloric and mechanical theories, to ignore the agency of +electricity and of magnetism, in the production of the varied +meteorological phenomena. But it will not do. The phenomena, grouped and +analyzed, disclose a potential-controlling, magneto-electric agency, and +meteorology will advance rapidly to perfection, as a simple, intelligible, +and practical science, <i>as soon as that agency is admitted</i>.</p> + +<p>Electricity is always perceptibly present in storms and showers within the +tropics. Most of the rain, from the tropical belt, falls from “thunder +showers.” So hurricanes and typhoons, and all tropical storms, are +confessedly, and in proportion to their intensity, “<i>highly electric</i>.” +This excess of quantity or activity of electricity, exists in connection +with the movable atmospheric machinery. When it moves up north in summer, +and arrives at its highest point of northern transit, <i>storms</i> are very +<i>uncommon</i>, and the tropical forms of cloud and showers, with thunder and +lightning, prevail. This is most obvious, if not most influential, where +the magnetic intensity is greatest. Violent showers, and gusts, and +tornadoes, are more frequent in this country than in Europe; and over the +area of greatest intensity, as in Ohio, than at a distance on the extreme +eastern or western coast. And the same is true over the intense magnetic +area of Asia.</p> + +<p>Electricity, too, like magnetism, has its diurnal,<span class="pagenum"><a name="Page_297" id="Page_297">[Pg 297]</a></span> and doubtless its +annual and decennial variations, and also its irregular ones, and they are +most obviously and intimately connected. Magnetism and electricity +together, constitute the aurora. Its culmination is in the magnetic +meridian—it affects the telegraph wires—is connected with the irregular +disturbances which affect the magnetic needle, and does not exist in the +limits of the trades, although occasionally seen from thence, when it +passes south, and near them.</p> + +<p>The aurora sometimes extends south in waves, as do the magneto-electric, +atmospheric, periodical changes of cold and heat, and storm, and sunshine. +<i>The aurora is connected with the formation of cloud</i>, and with a smoky +atmosphere, similar to that with which we are familiar in summer and +autumn. Thus Humboldt (Cosmos, vol. i. pp. 191, 192).</p> + +<p>“This connection of the polar light with the most delicate cirrus clouds, +deserves special attention, because it shows that the electro-magnetic +evolution of light is a part of a meteorological process. Terrestrial +magnetism here manifests its influence on the atmosphere, and on the +condensation of aqueous vapor. The fleecy clouds seen in Iceland, by +Thienemann, and which he considered to be the northern light, have been +seen in recent times by Franklin and Richardson, near the American north +pole, and by Admiral Wrangel on the Siberian coast of the Polar Sea. All +remarked ‘that the aurora flashed forth in the most vivid beams when +masses of cirrus-strata were hovering in the upper regions of the air, and +when these were so thin that their presence could<span class="pagenum"><a name="Page_298" id="Page_298">[Pg 298]</a></span> only be recognized by +the formation of a halo round the moon.’ These clouds sometimes range +themselves, even by day, in a similar manner to the beams of the aurora, +and then disturb the course of the magnetic needle in the same manner as +the latter. On the morning after every distinct nocturnal aurora, the same +superimposed strata of clouds have still been observed that had previously +been luminous. The apparently converging polar zones (streaks of clouds in +the direction of the magnetic meridian), which constantly occupied my +attention during my journeys on the elevated plateaux of Mexico, and in +northern Asia, belong, probably, to the same group of diurnal phenomena.”</p> + +<p>Mr. William Stevenson gives us (in the London, Edinburgh, and Dublin +Philosophical Magazine for July, 1853) an interesting article on the +connection between aurora and clouds. His observations on this most +important branch of the subject trace a connection between the aurora and +the formation of cloud, and open up, as he says, “a most interesting field +for observation which promises to lead to very important results.” Such +observations point with great significance, to the primary influence of +the magneto-electricity of the earth.</p> + +<p>To the difference in the magnetic intensity of the eastern portion of this +continent, compared with Europe and our western coast, very much of the +difference of climate, so far as temperature is involved, may be +attributed. We have seen in what manner the iso-thermal lines surround +these areas of intensity.<span class="pagenum"><a name="Page_299" id="Page_299">[Pg 299]</a></span> So the most excessive climate—that is, the +climate where the greatest extremes alternate, other things being equal, +is upon or near the line or area of greatest magnetic intensity. I say +other things being equal, because large bodies of water modify climates by +equalizing the seasons—making the summers cooler and the winters warmer +than the mean of the parallel.</p> + +<p>Thus, our great interior lakes modify the climate in relation to +temperature in their vicinity. Their summers are cooler and their winters +warmer; but westward of them the same line of equal summer temperature, or +iso-<ins class="correction" title="original: theral">thermal</ins> line, rises with considerable abruptness, and the winter, or +iso-cheimal line of equal temperature, falls in a similar manner. Thus, +the range of the thermometer, from the highest elevation to the lowest +depression, for the year, is very great, while in the tropics the range is +comparatively small. From observations made at the military posts of the +United States, Dr. Forrey deduced summer and winter lines of equal +temperature, starting from the vicinity of Boston and running west, which +showed most remarkably the rise of the summer lines as intensity +increased, and the fall of the winter lines in like manner.</p> + +<p>The influence of the lakes was also most obvious. The elevation of the +earth increases, going west, to about 700 feet at the surface of the +lakes, and to nearly 4,000 feet at the eastern base of the Rocky +Mountains; and, although temperature does not decrease to as great a +degree when the elevation<span class="pagenum"><a name="Page_300" id="Page_300">[Pg 300]</a></span> above the level of the sea is <i>gradual</i>, yet +some allowance should doubtless be made for that elevation on this line. +When that allowance is made, the ascent of the summer line, to the north, +over the area of greatest intensity, is strikingly apparent.</p> + +<p>Dr. Forrey also instituted a comparison between Fort Snelling, where the +climate is as excessive, and the range of the thermometer as great, as in +any portion of the continent in the same latitude, with Key West, and I +copy his diagram. It is very instructive, showing the gradual mean rise of +the temperature, from January to December, inclusive, while the cross +lines show the <i>extremes of each month</i>.</p> + +<p>Perhaps the most interesting part of it, is the illustration of the +monthly extremes, and the contrast between them, in the excessive climate +of Fort Snelling, and the tropical one of Key West. Each is a type of the +climate in which it is situated. The annual range and monthly extremes are +small in tropical countries, and large in extra-tropical ones. The extreme +range, or greatest elevation of heat, contrary to what is generally +supposed, is greater at Fort Snelling than at Key West. But the climate of +the latter is modified by the adjoining ocean.</p> + +<p>I copy, also, a table (p. 304), showing the range of the thermometer for +the year, and the maxima and minima, during each month, at several other +places in this country, and at London and Rome, for the purpose of showing +the extent of the ranges compared with those places; and also, that these +great changes in each month occur very uniformly all over the country, +and may always be expected, and with considerable regularity. They are +incident to our climate. I wish I could engrave the foregoing diagram, and +the following table, upon the mind of every man, woman, and child in the +country; and under it, in ever-visible letters, these words of precaution: +<span class="smcap">Conform to the peculiarities of your climate, and clothe yourselves, at +all times, in accordance with the alternations of the weather.</span> If heeded, +they would save thousands, every year, from premature death.</p> + +<p> </p> +<p><span class="pagenum"><a name="Page_301" id="Page_301">[Pg 301]</a></span></p> +<p class="center"><strong>Fig. 18.</strong></p> +<div class="figcenter"><img src="images/i0326tmb.jpg" alt="" /><br /> +<a href="images/i0326.jpg"><small>Larger Image</small></a></div> +<p><span class="pagenum"><a name="Page_302" id="Page_302">[Pg 302]</a></span></p> +<p> </p> + +<p><span class="pagenum"><a name="Page_303" id="Page_303">[Pg 303]</a></span>The effect of this difference of magnetic intensity upon the climate of +Europe is marked. There, the excessive summer heat, which our greater +magnetic intensity and larger volume of counter trade give us, is unknown. +Hence, while we can grow Indian corn (which requires the excessive summer +heat) over all the Eastern States, up to 45°, and in some localities east +of the lakes to 47° 30′, and to 50° west of them, to the base of the Rocky +Mountains, and notwithstanding the increase of elevation, they can not +grow it except over a limited area, and with limited success. Nor can +they, or the inhabitants of any other country except China, grow +profitably the kind of cotton which is so successfully grown in the +Southern States of the Union. Nor can China do so to a considerable +extent, because of the mountainous character of the surface. To a level +and remarkably watered country, greater magnetic and electric intensity, +and a greater volume of counter-trade, we are, and ever shall remain, +indebted, for an almost exclusive monopoly in the growth of two of the +most important staple productions of the earth. On the other hand, +although the same magnetic intensity, and its winter excess of positive +electricity and cold, make our winters extreme, there are but few of the +productions of temperate latitudes which we can not grow successfully, and +they are comparatively unimportant.</p> + +<p> <span class="pagenum"><a name="Page_304" id="Page_304">[Pg 304]</a></span></p> +<table border="0" cellpadding="0" cellspacing="0" summary="places"> +<tr><td colspan="2" class="btrl"> </td> + <td valign="top" class="btr" align="center">Fort Vancouver, Oregon Territory</td> + <td valign="top" class="btr" align="center">Fort Brady, outlet of Lake Sup.</td> + <td valign="top" class="btr" align="center">Hancock Barracks, Houlton, Me.</td> + <td valign="top" class="btr" align="center">Fort Armstrong, Rock Island, Ill.</td> + <td valign="top" class="btr" align="center">West Point, New York</td> + <td valign="top" class="btr" align="center">Washington, D. C.</td> + <td valign="top" class="btr" align="center">Jefferson Barracks, near St. Louis</td> + <td valign="top" class="btr" align="center">Fort King, interior of East Florid.</td> + <td valign="top" class="btr" align="center">Environs of London</td> + <td valign="top" class="btr" align="center">Rome, Italy</td></tr> +<tr><td colspan="2" class="btrl">Lat.</td> + <td align="center" class="btr">45° 37′</td> + <td align="center" class="btr">46° 39′</td> + <td align="center" class="btr">46° 10′</td> + <td align="center" class="btr">41° 28′</td> + <td align="center" class="btr">41° 22′</td> + <td align="center" class="btr">38° 53′</td> + <td align="center" class="btr">38° 28′</td> + <td align="center" class="btr">29° 12′</td> + <td align="center" class="btr">51° 31′</td> + <td align="center" class="btr">41° 54′</td></tr> +<tr><td class="blr" colspan="2">Annual Range.</td> + <td class="br" align="center">78</td> + <td class="br" align="center">110</td> + <td class="br" align="center">118</td> + <td class="br" align="center">106</td> + <td class="br" align="center">91</td> + <td class="br" align="center">84</td> + <td class="br" align="center">89</td> + <td class="br" align="center">78</td> + <td class="br" align="center">67</td> + <td class="br" align="center">62</td></tr> +<tr><td class="blr">Jan.</td> + <td class="br">Min.</td> + <td class="br" align="center">17</td> + <td class="br" align="center">-21</td> + <td class="br" align="center">-24</td> + <td class="br" align="center">-10</td> + <td class="br" align="center">-1</td> + <td class="br" align="center">14</td> + <td class="br" align="center">10</td> + <td class="br" align="center">33</td> + <td class="br" align="center">16</td> + <td class="br" align="center">29</td></tr> +<tr><td class="blr"> </td> + <td class="br">Max.</td> + <td class="br" align="center">58</td> + <td class="br" align="center">40</td> + <td class="br" align="center">41</td> + <td class="br" align="center">48</td> + <td class="br" align="center">53</td> + <td class="br" align="center">57</td> + <td class="br" align="center">60</td> + <td class="br" align="center">83</td> + <td class="br" align="center">49</td> + <td class="br" align="center">58</td></tr> +<tr><td class="blr">Feb.</td> + <td class="br">Min.</td> + <td class="br" align="center">32</td> + <td class="br" align="center">-22</td> + <td class="br" align="center">-11</td> + <td class="br" align="center">-6</td> + <td class="br" align="center"><span style="margin-left: .5em;">2</span></td> + <td class="br" align="center">16</td> + <td class="br" align="center">11</td> + <td class="br" align="center">43</td> + <td class="br" align="center">19</td> + <td class="br" align="center">33</td></tr> +<tr><td class="blr"> </td> + <td class="br">Max.</td> + <td class="br" align="center">55</td> + <td class="br" align="center">44</td> + <td class="br" align="center">42</td> + <td class="br" align="center">56</td> + <td class="br" align="center">56</td> + <td class="br" align="center">62</td> + <td class="br" align="center">70</td> + <td class="br" align="center">84</td> + <td class="br" align="center">54</td> + <td class="br" align="center">60</td></tr> +<tr><td class="blr">Mar.</td> + <td class="br">Min.</td> + <td class="br" align="center">32</td> + <td class="br" align="center">-7</td> + <td class="br" align="center">-1</td> + <td class="br" align="center">13</td> + <td class="br" align="center">16</td> + <td class="br" align="center">28</td> + <td class="br" align="center">31</td> + <td class="br" align="center">39</td> + <td class="br" align="center">24</td> + <td class="br" align="center">37</td></tr> +<tr><td class="blr"> </td> + <td class="br">Max.</td> + <td class="br" align="center">60</td> + <td class="br" align="center">51</td> + <td class="br" align="center">54</td> + <td class="br" align="center">70</td> + <td class="br" align="center">72</td> + <td class="br" align="center">70</td> + <td class="br" align="center">76</td> + <td class="br" align="center">87</td> + <td class="br" align="center">60</td> + <td class="br" align="center">65</td></tr> +<tr><td class="blr">Apr.</td> + <td class="br">Min.</td> + <td class="br" align="center">32</td> + <td class="br" align="center">18</td> + <td class="br" align="center">24</td> + <td class="br" align="center">33</td> + <td class="br" align="center">40</td> + <td class="br" align="center">36</td> + <td class="br" align="center">38</td> + <td class="br" align="center">54</td> + <td class="br" align="center">26</td> + <td class="br" align="center">44</td></tr> +<tr><td class="blr"> </td> + <td class="br">Max.</td> + <td class="br" align="center">70</td> + <td class="br" align="center">62</td> + <td class="br" align="center">74</td> + <td class="br" align="center">78</td> + <td class="br" align="center">62</td> + <td class="br" align="center">73</td> + <td class="br" align="center">83</td> + <td class="br" align="center">93</td> + <td class="br" align="center">69</td> + <td class="br" align="center">74</td></tr> +<tr><td class="blr">May.</td> + <td class="br">Min.</td> + <td class="br" align="center">32</td> + <td class="br" align="center">32</td> + <td class="br" align="center">81</td> + <td class="br" align="center">44</td> + <td class="br" align="center">47</td> + <td class="br" align="center">50</td> + <td class="br" align="center">45</td> + <td class="br" align="center">64</td> + <td class="br" align="center">33</td> + <td class="br" align="center">52</td></tr> +<tr><td class="blr"> </td> + <td class="br">Max.</td> + <td class="br" align="center">75</td> + <td class="br" align="center">79</td> + <td class="br" align="center">83</td> + <td class="br" align="center">84</td> + <td class="br" align="center">72</td> + <td class="br" align="center">85</td> + <td class="br" align="center">88</td> + <td class="br" align="center">97</td> + <td class="br" align="center">78</td> + <td class="br" align="center">80</td></tr> +<tr><td class="blr">June.</td> + <td class="br">Min.</td> + <td class="br" align="center">45</td> + <td class="br" align="center">41</td> + <td class="br" align="center">38</td> + <td class="br" align="center">57</td> + <td class="br" align="center">57</td> + <td class="br" align="center">59</td> + <td class="br" align="center">59</td> + <td class="br" align="center">73</td> + <td class="br" align="center">39</td> + <td class="br" align="center">60</td></tr> +<tr><td class="blr"> </td> + <td class="br">Max.</td> + <td class="br" align="center">95</td> + <td class="br" align="center">86</td> + <td class="br" align="center">90</td> + <td class="br" align="center">89</td> + <td class="br" align="center">79</td> + <td class="br" align="center">92</td> + <td class="br" align="center">95</td> + <td class="br" align="center">105</td> + <td class="br" align="center">80</td> + <td class="br" align="center">88</td></tr> +<tr><td class="blr">July.</td> + <td class="br">Min.</td> + <td class="br" align="center">40</td> + <td class="br" align="center">39</td> + <td class="br" align="center">45</td> + <td class="br" align="center">62</td> + <td class="br" align="center">64</td> + <td class="br" align="center">64</td> + <td class="br" align="center">50</td> + <td class="br" align="center">73</td> + <td class="br" align="center">41</td> + <td class="br" align="center">64</td></tr> +<tr><td class="blr"> </td> + <td class="br">Max.</td> + <td class="br" align="center">95</td> + <td class="br" align="center">84</td> + <td class="br" align="center">90</td> + <td class="br" align="center">95</td> + <td class="br" align="center">86</td> + <td class="br" align="center">94</td> + <td class="br" align="center">96</td> + <td class="br" align="center">102</td> + <td class="br" align="center">83</td> + <td class="br" align="center">91</td></tr> +<tr><td class="blr">Aug.</td> + <td class="br">Min.</td> + <td class="br" align="center">44</td> + <td class="br" align="center">49</td> + <td class="br" align="center">46</td> + <td class="br" align="center">60</td> + <td class="br" align="center">62</td> + <td class="br" align="center">63</td> + <td class="br" align="center">66</td> + <td class="br" align="center">74</td> + <td class="br" align="center">42</td> + <td class="br" align="center">62</td></tr> +<tr><td class="blr"> </td> + <td class="br">Max.</td> + <td class="br" align="center">95</td> + <td class="br" align="center">84</td> + <td class="br" align="center">85</td> + <td class="br" align="center">91</td> + <td class="br" align="center">87</td> + <td class="br" align="center">93</td> + <td class="br" align="center">96</td> + <td class="br" align="center">104</td> + <td class="br" align="center">79</td> + <td class="br" align="center">91</td></tr> +<tr><td class="blr">Sept.</td> + <td class="br">Min.</td> + <td class="br" align="center">43</td> + <td class="br" align="center">40</td> + <td class="br" align="center">33</td> + <td class="br" align="center">51</td> + <td class="br" align="center">56</td> + <td class="br" align="center">51</td> + <td class="br" align="center">51</td> + <td class="br" align="center">70</td> + <td class="br" align="center">34</td> + <td class="br" align="center">55</td></tr> +<tr><td class="blr"> </td> + <td class="br">Max.</td> + <td class="br" align="center">88</td> + <td class="br" align="center">75</td> + <td class="br" align="center">78</td> + <td class="br" align="center">87</td> + <td class="br" align="center">83</td> + <td class="br" align="center">88</td> + <td class="br" align="center">88</td> + <td class="br" align="center">99</td> + <td class="br" align="center">75</td> + <td class="br" align="center">85</td></tr> +<tr><td class="blr">Oct.</td> + <td class="br">Min.</td> + <td class="br" align="center">50</td> + <td class="br" align="center">27</td> + <td class="br" align="center">24</td> + <td class="br" align="center">82</td> + <td class="br" align="center">42</td> + <td class="br" align="center">33</td> + <td class="br" align="center">38</td> + <td class="br" align="center">41</td> + <td class="br" align="center">30</td> + <td class="br" align="center">46</td></tr> +<tr><td class="blr"> </td> + <td class="br">Max.</td> + <td class="br" align="center">66</td> + <td class="br" align="center">70</td> + <td class="br" align="center">72</td> + <td class="br" align="center">73</td> + <td class="br" align="center">69</td> + <td class="br" align="center">77</td> + <td class="br" align="center">80</td> + <td class="br" align="center">91</td> + <td class="br" align="center">68</td> + <td class="br" align="center">77</td></tr> +<tr><td class="blr">Nov.</td> + <td class="br">Min.</td> + <td class="br" align="center">32</td> + <td class="br" align="center">15</td> + <td class="br" align="center"><span style="margin-left: .5em;">4</span></td> + <td class="br" align="center">26</td> + <td class="br" align="center">36</td> + <td class="br" align="center">28</td> + <td class="br" align="center">27</td> + <td class="br" align="center">30</td> + <td class="br" align="center">22</td> + <td class="br" align="center">39</td></tr> +<tr><td class="blr"> </td> + <td class="br">Max.</td> + <td class="br" align="center">58</td> + <td class="br" align="center">58</td> + <td class="br" align="center">60</td> + <td class="br" align="center">64</td> + <td class="br" align="center">63</td> + <td class="br" align="center">66</td> + <td class="br" align="center">69</td> + <td class="br" align="center">82</td> + <td class="br" align="center">56</td> + <td class="br" align="center">67</td></tr> +<tr><td class="blr">Dec.</td> + <td class="br">Min.</td> + <td class="br" align="center">32</td> + <td class="br" align="center">-7</td> + <td class="br" align="center">-4</td> + <td class="br" align="center">15</td> + <td class="br" align="center">20</td> + <td class="br" align="center">17</td> + <td class="br" align="center">14</td> + <td class="br" align="center">36</td> + <td class="br" align="center">20</td> + <td class="br" align="center">31</td></tr> +<tr><td class="bblr"> </td> + <td class="bbr">Max.</td> + <td class="bbr" align="center">55</td> + <td class="bbr" align="center">42</td> + <td class="bbr" align="center">53</td> + <td class="bbr" align="center">62</td> + <td class="bbr" align="center">56</td> + <td class="bbr" align="center">61</td> + <td class="bbr" align="center">64</td> + <td class="bbr" align="center">79</td> + <td class="bbr" align="center">53</td> + <td class="bbr" align="center">60</td></tr></table> + + +<p> </p> +<p><span class="pagenum"><a name="Page_305" id="Page_305">[Pg 305]</a></span>This excess of magnetic intensity and electricity not only gives a +peculiar character to our vegetation, but also to our race, our animals, +and every thing. He who supposes that the restless activity and energy of +the people of the United States is the result of habit, or education, or +any fortuitous circumstances alone, is mistaken. Let him watch the +contrast in his own feelings during those occasional languid, damp, and +sultry, although not thermometrically, hot days—which so much resemble +the summer weather of England—with those days of bright, bracing, N. W. +and S. W. air, so much more frequent here, and he will appreciate the +difference. That term “bracing,” so much in use, will express the effect +of this peculiar weather. It “girds up the loins,” both of body and mind. +Men and animals can work with more ease, even in our peculiar extremes of +heat, than they can in England, and fatten with less.</p> + +<p>A similar difference in degree is found between our climate and that of +the Pacific portion of our country. Something is due to the difference in +the volume and moisture of the counter-trades, and something to the +contiguity of the Pacific Ocean; but to the<span class="pagenum"><a name="Page_306" id="Page_306">[Pg 306]</a></span> difference in +magneto-electric intensity, the contrast is mainly due. Corn and cotton +will be grown, to some extent, in the valleys west of the meridian of +105°, but never as successfully as east of it.</p> + +<p>The aurora is periodical, like all the other atmospheric phenomena, but +its periodicity is not accurately ascertained. It is believed to have +occurred much oftener during the second quarter of this century, than +during the first. It is known, however, to occur most frequently in the +spring and fall; and during those periods when the active and rapid +transit of the atmospheric machinery produces the greatest degree of +magnetic disturbance. This identifies it with terrestrial magnetism. +Dalton gives us the following table of observations, arranged according to +the months when they were seen.</p> + +<table border="0" cellpadding="0" cellspacing="0" summary="months"> +<tr><td class="btrl"> </td> + <td class="btr"><small>Jan.</small></td> + <td class="btr"><small>Feb.</small></td> + <td class="btr"><small>Mar.</small></td> + <td class="btr"><small>Apr.</small></td> + <td class="btr"><small>May.</small></td> + <td class="btr"><small>June.</small></td> + <td class="btr"><small>July.</small></td> + <td class="btr"><small>Aug.</small></td> + <td class="btr"><small>Sept.</small></td> + <td class="btr"><small>Oct.</small></td> + <td class="btr"><small>Nov.</small></td> + <td class="btr"><small>Dec.</small></td></tr> +<tr><td class="btrl">(1)</td> + <td class="btr">18</td> + <td class="btr">18</td> + <td class="btr">26</td> + <td class="btr">32</td> + <td class="btr">21</td> + <td class="btr" align="center">5</td> + <td class="btr" align="center">2</td> + <td class="btr">21</td> + <td class="btr">23</td> + <td class="btr">36</td> + <td class="btr">38</td> + <td class="btr"><span style="margin-left: .5em;">9</span></td></tr> +<tr><td class="blr">(2)</td> + <td class="br">21</td> + <td class="br">18</td> + <td class="br">23</td> + <td class="br">13</td> + <td class="br"><span style="margin-left: .5em;">3</span></td> + <td class="br" align="center">2</td> + <td class="br" align="center">1</td> + <td class="br"><span style="margin-left: .5em;">3</span></td> + <td class="br">35</td> + <td class="br">22</td> + <td class="br">22</td> + <td class="br">21</td></tr> +<tr><td class="blr">(3)</td> + <td class="br">21</td> + <td class="br">27</td> + <td class="br">22</td> + <td class="br">12</td> + <td class="br"><span style="margin-left: .5em;">1</span></td> + <td class="br" align="center">5</td> + <td class="br" align="center">7</td> + <td class="br"><span style="margin-left: .5em;">9</span></td> + <td class="br">34</td> + <td class="br">50</td> + <td class="br">26</td> + <td class="br">15</td></tr> +<tr><td class="bblr">(4)</td> + <td class="bbr"><span style="margin-left: .5em;">5</span></td> + <td class="bbr"><span style="margin-left: .5em;">6</span></td> + <td class="bbr"><span style="margin-left: .5em;">4</span></td> + <td class="bbr"><span style="margin-left: .5em;">8</span></td> + <td class="bbr">10</td> + <td class="bbr" align="center">7</td> + <td class="bbr" align="center">6</td> + <td class="bbr">14</td> + <td class="bbr">14</td> + <td class="bbr">17</td> + <td class="bbr"><span style="margin-left: .5em;">5</span></td> + <td class="bbr"><span style="margin-left: .5em;">6</span></td></tr></table> + +<p>(1) contains those observed by him at Kendall; (2) are taken from another +list; (3) is <span class="smcap">Marian’s</span> list of those observed before 1732; and (4), those +seen in the State of New York in 1828 and 1830.</p> + +<p>Mr. Stevenson’s table of those observed by him at Dunse, from 1838 to +1847, inclusive, is as follows:</p> + +<table border="0" cellpadding="0" cellspacing="5" summary="dunse"> +<tr><td><small>Jan.</small></td><td><span class="spacer2"> </span></td> + <td><small>Feb.</small></td><td><span class="spacer2"> </span></td> + <td><small>Mar.</small></td><td><span class="spacer2"> </span></td> + <td><small>Apr.</small></td><td><span class="spacer2"> </span></td> + <td><small>May.</small></td><td><span class="spacer2"> </span></td> + <td><small>June.</small></td><td><span class="spacer2"> </span></td> + <td><small>July.</small></td><td><span class="spacer2"> </span></td> + <td><small>Aug.</small></td><td><span class="spacer2"> </span></td> + <td><small>Sept.</small></td><td><span class="spacer2"> </span></td> + <td><small>Oct.</small></td><td><span class="spacer2"> </span></td> + <td><small>Nov.</small></td><td><span class="spacer2"> </span></td> + <td><small>Dec.</small></td></tr> +<tr><td align="center">32</td><td> </td> + <td align="center">20</td><td> </td> + <td align="center">18</td><td> </td> + <td align="center">18</td><td> </td> + <td align="center">3</td><td> </td> + <td align="center">0</td><td> </td> + <td align="center">2</td><td> </td> + <td align="center">14</td><td> </td> + <td align="center">43</td><td> </td> + <td align="center">34</td><td> </td> + <td align="center">30</td><td> </td> + <td align="center">23</td></tr></table> + +<p><span class="pagenum"><a name="Page_307" id="Page_307">[Pg 307]</a></span>Observations in this country correspond substantially with the foregoing. +They are, however, seen here in the summer months more frequently than in +Europe. See an article by Mr. Herrick (American Journal of Science, vol. +33. p. 297). In this, also, they conform to our greater magnetic intensity +and more excessive climate.</p> + +<p>The auroras appear to follow the polar belts of condensation and +precipitation. Dalton considers them indications of fair weather. They are +often most brilliant just after a storm has passed, but their continuance +is no indication that another will not follow within the usual period.</p> + +<p>The condensation with which the aurora is connected, is not, in my +judgment, often in the counter-trade, or below it, but above, where feeble +condensation has been seen by aeronauts when invisible at the surface of +the earth. Neither the height of this condensation, not that of the +aurora, have been satisfactorily ascertained. The aurora of April 7th, +1847, was a favorable one for observation. It was carefully and +attentively watched by Professor Olmsted, Mr. Herrick, Dr. Ellsworth, and +others, and they are intelligent and skillful observers.<small><a name="f9.1" id="f9.1" href="#f9">[9]</a></small> But the nature +of the aurora forbids reliance on parallax, or measurements founded on the +time when, any portion of the bow or arch rises in range of a particular +star. The bow or arch moves southwardly, but the same rays or currents do +not. The wave of magnetic <i>activity</i> moves south, and each successive +current, as it is reached by the <i>impulse</i>, becomes luminous.<span class="pagenum"><a name="Page_308" id="Page_308">[Pg 308]</a></span> Hence the +observers, when distant, do not see, at the same time, or at different +times, the same rays. The phenomenon is unquestionably magneto-electric. +Electricity becomes luminous in a vacuum, and De la Rive, by combining the +electric currents with those of magnetism, produced all the peculiarities +of the aurora. The magnetic currents, passing from the earth, have +associated electric ones in connection, and these, in the upper attenuated +atmosphere, become luminous. Whether, as De La Rive supposes, by combining +with the positive electricity existing there, or because the associated +electric currents are <i>then</i> in excess, not being intercepted by +atmospheric vapor and returned to the earth in rain, we can not know, nor +is it very important we should.</p> + +<p>Having thus taken a general view of the nature of magnetism and its +associated electricities, and their connection with the general and +obvious peculiarities of climate, let us approach more nearly the varied +atmospheric phenomena, resulting from variations of pressure, temperature, +condensation, and wind, and give them a closer consideration. They all +have regularity and periodicity—they all occur in degree, and in +connection with magnetism and electricity, during the twenty-four hours of +every serene and normal summer’s day. Grouped together, in comparison with +the changes in the activity and force of the magnetic elements, their +connection is clearly discernible.</p> + +<p>The day may be said, with truth, to commence, in some portion of the +summer, at 4 <span class="smcaplc">A.M.</span> The <span class="pagenum"><a name="Page_309" id="Page_309">[Pg 309]</a></span>atmospheric does at all seasons. At that hour the +barometer is at its morning minimum. It has, as we have said, a +perceptible diurnal variation of two maxima and two minima. Its periods of +depression are at 4 <span class="smcaplc">A.M.</span>, and 4 <span class="smcaplc">P.M.</span>, and of elevation at 10 <span class="smcaplc">A.M.</span>, and 10 +<span class="smcaplc">P.M.</span> The difference between the elevation and depression is considerable +within the tropics, where Humboldt tells us the hour of the day can be +known by the height of the barometer, and it decreases toward the poles. +At 4 <span class="smcaplc">A.M.</span> it is then at one of its minima, and rises till 10 o’clock.</p> + +<p>At, or about the same period, and sometimes when the barometer is falling, +and previous thereto, there is a tendency to fog in localities subject to +that condensation. This tendency is sometimes observed at the other +barometric minimum, late in the afternoon or early in the evening, but +less frequently. The tendency to fog condensation is greatest in this +country about the morning minimum. It seems to be owing to the influence +of the earth; it is confined to the surface atmosphere, and is apparently +produced by the inductive agency of the negative electricity of the earth. +It disappears, whether it be high or low fog, about the time when the +barometer attains its morning maximum, or about 10 <span class="smcaplc">A.M.</span></p> + +<p>At about that period, when there has been fog, or earlier, when there has +not, and sometimes as early as 8 <span class="smcaplc">A.M.</span>, there is a tendency to trade +condensation—cirrus in mid-winter, and a cumulus in mid-summer, and, +during the intermediate time, a tendency to cirro-stratus, partaking more +or less of the<span class="pagenum"><a name="Page_310" id="Page_310">[Pg 310]</a></span> character of one or the other, according to the season.</p> + +<p>Temperature, in summer, commences its diurnal elevation about 4 <span class="smcaplc">A.M.</span>, +also, and rises till about 2 <span class="smcaplc">P.M.</span> From that time it falls with very little +variation till 4 o’clock the next morning. It has but one maximum and one +minimum in the twenty-four hours.</p> + +<p>As the morning barometric maximum approaches, and the heat increases the +magnetic activity, condensation in the trade appears, or induced +condensation in the upper portion of the surface atmosphere, that portion +near the earth is affected and attracted—and the “wind rises,” according +to the locality, the season, and the activity of the condensation. The +tendency to blow increases with the tendency to trade and cumulus +condensation, and continues till toward night, when it gradually dies +away, unless there be a storm approaching. As the heat increases, and +stimulates magnetism into activity, the magnetic needle commences moving +to the west, its regular diurnal variation, and continues to do so until +about 2 <span class="smcaplc">P.M.</span>, when it commences returning to the east, and so continues to +return until 10 <span class="smcaplc">P.M.</span>, when it moves west again until 2 <span class="smcaplc">A.M.</span>, and from +thence to the east, till 8 <span class="smcaplc">A.M.</span></p> + +<p>Similar variations also take place in the horizontal force, as evinced by +the action of the magnetometer needle, and in the vertical force, as shown +by the oscillations. So that it is evident that there are two maxima, and +two minima of magnetic activity every day, shown by all the methods by +which we measure<span class="pagenum"><a name="Page_311" id="Page_311">[Pg 311]</a></span> magnetic action and force—more than double at the acme +of northern summer transit over that of winter, and proceeding <i>pari +passu</i>, with the other daily phenomena—evincing the same irregular action +which the other phenomena evince. Still another phenomenon, which has a +daily change, is electric tension, or the increase or decrease in the +tension of the positive or true atmospheric electricity.</p> + +<p> </p> +<p><span class="pagenum"><a name="Page_312" id="Page_312">[Pg 312]</a></span></p> +<p class="center"><strong>Fig. 19.</strong></p> +<div class="figcenter"><img src="images/fig19tmb.jpg" alt="" /><br /> +<a href="images/fig19.jpg"><small>Larger Image</small></a></div> +<p> </p> + +<p><span class="pagenum"><a name="Page_313" id="Page_313">[Pg 313]</a></span>The following table shows the mean two hourly tensions for three years, at +Kew, viz.:</p> + +<table border="0" cellpadding="0" cellspacing="5" summary="tensions"> +<tr><td>Hours</td> + <td>12 <small>P.M.</small> </td> + <td>2 <small>A.M.</small> </td> + <td>4 <small>A.M.</small> </td> + <td>6 <small>A.M.</small> </td> + <td>8 <small>A.M.</small> </td> + <td>10 <small>A.M.</small> </td></tr> +<tr><td>Number of observations </td><td>655</td><td>784</td><td>804</td><td>566</td><td>1,047</td><td>1,013</td></tr> +<tr><td>Tension</td><td>22.6</td><td>20.1</td><td>20.5</td><td>34.2</td><td>68.2</td><td>88.1</td></tr> +<tr><td> </td></tr> +<tr><td>Hours</td> + <td>12 <small>A.M.</small></td> + <td>2 <small>P.M.</small></td> + <td>4 <small>P.M.</small></td> + <td>6 <small>P.M.</small></td> + <td>8 <small>P.M.</small></td> + <td>10 <small>P.M.</small></td></tr> +<tr><td>Number of observations</td><td>848</td><td>858</td><td>878</td><td>874</td><td>878</td><td>1,007</td></tr> +<tr><td>Tension</td><td>75.4</td><td>71.5</td><td>69.1</td><td>84.8</td><td>102.4</td><td>104</td></tr></table> + +<p>From this it will be seen that the tension of electricity is at a minimum +at 4 <span class="smcaplc">A.M.</span>, also, that it rises till 10, falls till 4 <span class="smcaplc">P.M.</span>, but not as +rapidly, rises till 10, falls again till 4 <span class="smcaplc">A.M.</span>, or the close of the +meteorological day—having two maxima and minima, as have most of the +phenomena thus far considered.</p> + +<p>In order to see what the connections between these ever-present, daily +phenomena are, and their connection with other phenomena, and that we may +understand their normal conditions, I will trace them approximately in a +diagram (figure <a href="#Page_248">17</a>.)</p> + +<p>The foregoing diagram of the daily phenomena of a summer’s day, when no +disturbing causes are in operation, no storm existing within influential +distance, and no unusual intensity or irregular action of<span class="pagenum"><a name="Page_314" id="Page_314">[Pg 314]</a></span> any of the +forces present, affords a basis for considering the various phenomena of +the weather in all its changes and conditions.</p> + +<p>It is obvious that the other phenomena do not all depend upon temperature +merely, if indeed any of them do.</p> + +<p>Temperature has but one maximum and minimum, and that is exceedingly +regular, and does not correspond with any other.</p> + +<p>The barometer has two; electric tension, two; magnetic activity, two; +condensation, two—one the formation of cloud, and the other the formation +of fog and dew; wind, one—resembling temperature in that respect, but +embracing a much less period.</p> + +<p>Fog forms at one barometric minimum, and cloud at another.</p> + +<p>Fog forms at one period of the magnetic variation, cloud at another.</p> + +<p>The formation of cloud corresponds with the greatest intensity of magnetic +action, and its associate electricities. But the oscillations of the +barometer do not correspond with either. And thus, then, we connect them:</p> + +<table border="0" cellpadding="0" cellspacing="0" summary="cause"> +<tr><td class="br" align="center"><span class="smcaplc">CAUSE.</span></td> + <td class="br" align="center"><span class="smcaplc">EFFECT.</span></td> + <td class="dent" align="center"><span class="smcaplc">EFFECT.</span></td></tr> +<tr><td class="br" valign="top">Increase of magnetic or<br />magneto-electric activity,<br />as shown by declination<br />and increase of horizontal<br />and vertical force.</td> +<td class="br" valign="top">Decrease of pressure.<br /><br />Of positive electric tension.<br /><br />Of surface condensation,<br /><i>i. e.</i>, fog and dew.</td> +<td class="dent" valign="top">Increase of primary<br />condensation.<br /><br />Of wind.<br /><br />Of electrical disturbance and<br />phenomena in the trade and its<br />vicinity.</td></tr></table> + +<p>This connection is equally obvious if the order is reversed—thus;</p> + + +<p><span class="pagenum"><a name="Page_315" id="Page_315">[Pg 315]</a></span></p> + +<table border="0" cellpadding="0" cellspacing="0" summary="cause"> +<tr><td class="br" align="center"><span class="smcaplc">CAUSE.</span></td> + <td class="br" align="center"><span class="smcaplc">EFFECT.</span></td> + <td class="dent" align="center"><span class="smcaplc">EFFECT.</span></td></tr> +<tr><td class="br" valign="top">Decrease of magnetic or<br />magneto-electric activity.</td> +<td class="br" valign="top">Increase of pressure.<br /><br />Of tension of atmospheric<br />electricity.<br /><br />Of surface condensation,<br /><i>i. e.</i>, fog and dew.</td> +<td class="dent" valign="top">Disappearance of primary<br />condensation.<br /><br />Of wind, and<br /><br />Of electric disturbance in the<br />trade and its vicinity.</td></tr></table> + + +<p>If we examine still more particularly the different phenomena, we shall +find the same relative action of the forces carried into all the +atmospheric conditions, however violent.</p> + +<p>1. The barometer falls when horizontal magnetic force, and a tendency to +cloud and wind, increase; and rises when they decrease. This corresponds +with the character of the irregular barometric oscillation. Barometric +depressions accompany clouds and winds, and are in proportion to them, and +are all greatest where magnetic force is greatest. The barometer also +rises as the magnetic energy decreases. Do the magnetic currents, passing +upward with increased force, lift, elevate the atmosphere? How, then, are +we to explain the increased range of the oscillations, as the center of +atmospheric machinery is reached, where magnetism has least intensity, and +the perpendicular currents are less, and attraction is less? Attraction is +greatest where intensity is greatest, and there the barometer stands +highest, and the diurnal range is least. Is it then the attraction of +magnetism which produces the barometric oscillations? If so, how then can +we explain the diurnal fall while magnetism is most active?</p> + +<p>Perhaps we have not yet arrived at such a knowledge<span class="pagenum"><a name="Page_316" id="Page_316">[Pg 316]</a></span> of the nature of +magnetism as is necessary to a correct answer of those questions. Faraday +has taught us that the lines of magnetic force are close curves, passing +into the atmosphere, and over to the opposite hemisphere, and returning +through the earth, out on the opposite side in like manner, and back +again, passing twice through the earth and twice through the atmosphere. +All we know of this is what the iron filings indicate, and we do not know +how much reliance to place upon the indications they give. But if Faraday +is right, the sun will, twice each day, intersect and stimulate into +increased activity the same closed magnetic curve—once when it is coming +out of the earth, during our day, when its influence will be the most +active, and once when it is returning on the opposite side of the earth; +and a second, but feebler magnetic and electric maximum, may be occasioned +by its action on the opposite and returning closed curve of the same +current. However this may be, it is exceedingly difficult to conceive, of +any adequate influence exerted by the tension of vapor.</p> + +<p>So the mid-day barometric minimum may be caused by the attraction of the +earth, in a state of increased magnetic activity and intensity, upon the +counter-trade, and its consequent approach or settling toward the earth. +Observation, as I have already said, pointedly indicates such a state of +things. So the increased magnetic activity, with or by its associate +electricity, acts upon the electricity of the counter-trade, condensation +takes place, the electricity is disturbed in the surface-atmosphere, by +induction, and<span class="pagenum"><a name="Page_317" id="Page_317">[Pg 317]</a></span> its tension is changed. Opposite electrical conditions are +induced in the surface strata, and attraction takes place. The air moves +easily, and thus the attractions originate the winds. Secondary currents +are induced, as in all other cases of electric activity, and winds, in +<i>different strata</i> and directions, occur, with or without cumulus, or scud +condensation, according to their activity, and the proportion of moisture +of evaporation they may contain.</p> + +<p>I am well aware that the various received theories of meteorology +attribute condensation to the action of cold, mingling of colder strata, +etc. But I think that view will have to be abandoned.</p> + +<p>It assumes that moisture is evaporated and held in the atmosphere by +latent heat, which is given out during condensation, and actually warms +the surrounding atmosphere. Thus, the Kew Committee undertook to explain +the development of greater heat, at the elevation where they, in fact, +found the counter-trade. But how unphilosophical to suppose a portion of +the air or vapor contained in it, can give out to another adjoining +portion <i>more heat than is necessary to produce an equilibrium</i>. This can, +indeed, be done by experiment—<i>but the experiment is made with currents +of electricity</i>. How unphilosophical, too, to talk of latent heat in +connection with evaporation, <i>at the lowest temperature known</i>. +Meteorologists must revise their opinions on the subject of condensation. +This latent heat has never been actually met with; on the contrary, the +most sudden and complete condensations of the vapor of the atmosphere are +attended by as sudden and extraordinary productions<span class="pagenum"><a name="Page_318" id="Page_318">[Pg 318]</a></span> of cold, and +consequent hail, and the connection between condensation and electricity +is shown by too many facts to permit the old theory to stand.</p> + +<p><i>Fog never forms with the thermometer below 32°.</i> It is mainly a <i>summer +condensation</i>, especially high fog. It has been attributed to the cooling +effect of an atmosphere colder than the earth, but it often occurs when +the earth is the coldest, and when the vapor, as it rises, is colder than +the air, and could not give out heat to a warmer medium. (See American +Journal of Science, vol. xliv. p. 40.) Again, it is not mere condensation, +but a formation of globules or vesicles, hollow, and the air expanded in +them, by means of which they float like a soap bubble which contains the +warm air of the breath. Is not every vesicle a model shower, positively +electrified on the outside, negatively in the center, or the reverse, +according to the strata, with the air expanded in the middle by the excess +of heat which negative electricity detains? Look at them, as they attach +themselves to the slender nap of the cloth you wear, when passing through +them, and see how many of them it would require to form a large drop of +rain. The clouds are of a similar vesicular character, and rain does not +fall till the vesicles unite to form drops. Sudden and extreme cold is +indeed produced in the hail-storm, when, above, below, and around it, the +temperature is unaffected. Testu, Wise, and other aeronauts, have so found +it, and the hail tells us it is so. But it is idle to say it results from +radiation. All the phenomena of the sudden, violent hail-storms are +electric in an extraordinary degree.<span class="pagenum"><a name="Page_319" id="Page_319">[Pg 319]</a></span> The electricity is disturbed and +separated—the associated heat continues with the negative, and leaves the +positive portion of the cloud, and a corresponding reduction of +temperature results. So Masson found in his eudiometrical analytical +experiments the <i>negative</i> wire would heat to fusion, while the positive +was cold. (See London, Edinburgh, and Dublin Journal of Science for +December, 1853.) This disturbed electricity is diffused over the vesicles. +Listen to the thousand <i>crackling</i> sounds which initiate the clap of +thunder, and may be heard when the lightning strikes near you; produced by +the gathering of the lightning from as many points of the cloud where it +was diffused, to unite in one current and produce the “clap” or +“peal”—and to the “pouring” of the rain, which follows the union of the +vesicles, after the excess of repelling electricity is discharged.</p> + +<p>No <i>change</i> of temperature is observed when fogs form, except the ordinary +change between night and day; and it seems perfectly obvious, in looking +at all the phenomena, that fogs form at a temperature of 70° or 75°, in +consequence of the electric influence of the earth upon the adjoining +surface-atmosphere; and, when formed, they withstand the most intense +action of a summer sun, till the time of day arrives for the barometric +and electric tension to fall, condensation to take place in the +counter-trade above, and wind to be induced. Who that has noticed the +almost blistering force of the solar rays, as they break through a section +of high fog, about 10 <span class="smcaplc">A.M.</span>, can forget them.</p> + +<p>Fogs form near the earth, during the night, when the atmosphere above is +loaded with moisture many<span class="pagenum"><a name="Page_320" id="Page_320">[Pg 320]</a></span> degrees colder, and yet remains free from +condensation. On the other hand, during the heat of the day, and of the +hottest days, the heavy rains condense above—nay, they frequently fall at +a temperature of 75° to 80°, in the tropics, and of 50° to 55° in +mid-winter here.</p> + +<p>Thus far, an adherence to the opinion that condensation was simply a +cooling process; the driving out of its latent heat, not merely to another +body to make an equilibrium, but “<i>getting rid of it</i>” by positive active +radiation, or in some other way, so as to cool off and condense, has +involved the formation and classification of clouds in obscurity. Hopkins +(Atmospheric Changes, p. 331) laments this, but fettered by a false and +imperfect theory, in relation to the tension of vapor, he falls into a +similar error.</p> + +<p>Now, there are, as we have seen, peculiar, distinctly-marked varieties of +cloud, connected with peculiar and distinctly-marked conditions of the +atmosphere, <i>irrespective of temperature</i>. None of the theories advanced, +account, or profess to account for the differences in either. No +modification of the calorific theory will account for them. They differ in +shape, in color, in tendency to precipitation, in line of progress, and in +electrical character. The explanation of this is found in the fact, that +they form in distinct and different strata, partake of the positive +electric character of the one, or the negative of the other; or are +secondary, induced by the action of a primary condensation in a different +stratum. There is not any mingling of the different strata, as has been +supposed; and many other facts than those to which we<span class="pagenum"><a name="Page_321" id="Page_321">[Pg 321]</a></span> have alluded, show +that the formation of cloud is a magneto-electric process.</p> + +<p>The observations of Reid show that every violent shower cloud has the +electricities disturbed, and portions of it are positive, and others +negative. Howard gives us the following <i>résumé</i> of Reid’s observations:</p> + +<div class="blockquot"><p>“From an attentive examination of Reid’s observations I have been +able to deduce the following general results:</p> + +<p>“1. <i>The positive electricity, common to fair weather, often yields +to a negative state before rain.</i></p> + +<p>“2. <i>In general, the rain that first falls, after a depression of the +barometer, is</i> <span class="smcaplc">NEGATIVE</span>.</p> + +<p>“3. <i>Above forty cases of rain, in one hundred, give negative</i> +electricity; although the state of the atmosphere is positive, before +and afterward.</p> + +<p>“4. <i>Positive rain, in a positive atmosphere, occurs more rarely</i>: +perhaps fifteen times in one hundred.</p> + +<p>“5. <i>Snow and hail, unmixed with rain, are positive, almost without +exception.</i></p> + +<p>“6. <i>Nearly forty cases of rain, in one hundred, affected the +apparatus with both kinds</i> of electricity; sometimes with an +interval, in which no rain fell; and so, that a positive shower was +succeeded by a negative; and, <i>vice versâ</i>; at others, the two kinds +alternately took place during the same shower; and, it should seem, +<i>with a space of non-electric rain between them</i>.”</p></div> + +<p>Howard attributes, with great apparent probability, the successive +differences in the electrical character of the rain, to the passage of +different portions of the cloud, having different polarity, over the place +of observation. So <i>positive hail</i>, and <i>negative rain</i> fall in <i>parallel +bands</i> from the same cloud. Many such instances are on record. It should +be remembered that he is describing the phenomena in the showery climate +of England.</p> + +<p>But the most decisive, perhaps, as well as practically important evidence +of the influence of magnetism, or magneto-electricity, in meteorological +phenomena, is<span class="pagenum"><a name="Page_322" id="Page_322">[Pg 322]</a></span> derived from the action of storms. My observation has been +limited, for my life has been, and must be, a practical one. But, subject +to future, and I hope speedy corroboration, or correction, by extensive +systematic observation, I think I may venture to divide all storms into +four kinds:</p> + +<p>1. Those which come to us from the tropics, and constitute the class +investigated by Mr. Redfield. That these are of a magneto-electric +character is evident. They originate near the line of magnetic intensity, +over, or in the vicinity of, the volcanic islands of the tropics; are +largely accompanied by electrical phenomena; extend laterally as they +progress north; induce and create a change of temperature in advance of +them, and do not abate until they pass off over the Atlantic to the E. or +N. E., and perhaps not until they reach the Arctic circle. Their extensive +and continued action is not owing to any mere <i>mechanical agency</i> of the +adjoining passive air, or other supposed currents, originated, no man can +tell how, but they concentrate upon themselves the local magnetic currents +as they pass over and intersect them, and, by their inductive action upon +the surface-atmosphere, in different directions, attract it under them, +and within their more active influence. Here the action of the magnetic +currents is probably the primary cause, but the power of the storm to +concentrate upon itself the new magnetic currents which it intersects as +it enters each new, successive field, enables them to maintain and extend +their action.</p> + +<p>The following diagram illustrates the course and<span class="pagenum"><a name="Page_323" id="Page_323">[Pg 323]</a></span> gradual enlargement of a +mid-autumn tropical storm, which induces a S. E. wind in front, and +occasions a thaw.</p> + +<p> </p> +<p class="center"><strong>Fig. 20.</strong></p> +<div class="figcenter"><img src="images/i0348.jpg" alt="" /></div> +<p> </p> + +<p>2. Another class originate at the N. W., and extend gradually south +easterly on the magnetic meridian. These are most frequent in summer, +forming belts of showers, but occur, I believe, at all seasons of the +year. They seem to be produced by magnetic waves passing south, and are +followed in autumn and winter, and sometimes in summer, by the peculiar N. +W. wind and scud, and a term of cooler weather.</p> + +<p>Thus, it is believed that many, perhaps all of the alternating terms of +heat and cold, are dependent on magnetic waves passing over the country in +a similar manner, with a greater or less belt of condensation between +them, and depending on peculiar magnetic<span class="pagenum"><a name="Page_324" id="Page_324">[Pg 324]</a></span> action traveling in the same +way. The S. E. extension of showers and storms, and the cooler changes of +temperature which immediately follow them; with light N. W. wind in +mid-summer, and with it fresher at earlier and later periods, in the form +of northers blowing violently, according to the season, are intimately +connected, and indicate such waves. The indication is strengthened also by +the frequent progress of auroras in like manner, occurring usually after +the belt of condensation has passed, and frequently following it. The +clouds and currents of the atmosphere, so far as I have been able to +discover, show no permanent current from the pole to the atmospheric +equator, compensating for the counter-trade; and that compensation is +furnished by the periodical but frequent atmospheric waves, connected with +the periodical changes of storm, and cloud, and sunshine, which gradually +extend from north to south, in or near the magnetic meridian. Perhaps such +compensating currents are found west of the magnetic poles, as we have +suggested, and make the N. E. and northerly dry winds of Western Europe +and the Pacific; but, in the present state of our knowledge, it is +impossible to say that they are. If it be so, the compensation they +furnish must be small; for the volume of counter-trade which is not +depolarized before it reaches the Arctic circle, and which passes round +the magnetic pole, must be very small. A majority of our periodical +changes, during the northern transit, and I believe at all seasons, are of +this character; and, I have reason to believe, from observation, in<span class="pagenum"><a name="Page_325" id="Page_325">[Pg 325]</a></span> one +or two cases, that where belts of rains and showers begin, over <i>any +locality</i> in the United States, they may assume this character. I have +been in Saratoga when an easterly storm commenced <i>south of that place</i>; +the condensation and mackerel sky being visible at the south, and no cloud +formation or rain occurring there at the time, and have traced it +afterward as a belt which had a lateral extension south-eastward. Leaving +that place immediately after a belt had passed south, I have overtaken it +by railroad, and run into it again before arriving at New York; and +witnessed its subsequent extension south-eastwardly, out over the +Atlantic. I have witnessed the approach of such a belt in the spring, at +Sandusky, upon Lake Erie, and its passage over to the S. E., followed by +the N. W. wind, as Mr. Bassnett describes them at Ottawa, and run under +the attenuated edge of the same belt, on the same day, on the way to +Pittsburg, leaving the N. W. wind behind, but finding it present again +with clear sky on the following morning. I have seen hundreds of them +approach from the north, and pass to S. E., out over the Atlantic; +followed by the N. W. wind in spring and autumn. This class of storms pass +off toward, and doubtless over the track, of our European steamers and +packets. I know this, for I witness it nearly every month in the year. It +is not a matter of speculation, but of actual, long-continued observation. +Probably, as one approaches the Gulf Stream, and when over it, its induced +winds may be more violent. It is time our navigators understood this; and +that all the gales of the North Atlantic, certainly, are not<span class="pagenum"><a name="Page_326" id="Page_326">[Pg 326]</a></span> rotary; and +do not approach from the S. W. in the same manner as the class +investigated by Mr. Redfield do. Where a fresh southerly or south-westerly +wind is followed by any considerable cirro-stratus or +stratus-condensation, it is usually of this character.</p> + +<p>The following diagram exhibits the peculiarities of this class of storms. +It is intended to represent the same storm or belt of showers, on <i>two +successive</i> days, and, of course, its usual rate of southerly extension:</p> + +<p> </p> +<p class="center"><strong>Fig. 21.</strong></p> +<div class="figcenter"><img src="images/i0351.jpg" alt="" /></div> +<p> </p> + +<p>This class of storms, or belts of showers, present the following +succession of phenomena in summer:</p> + +<p>1. Still warm weather, one or more days.</p> + +<p>2. Fresh southerly wind, one or more days; if more than one, dying away at +the S. W., at night-fall, but continuing into the evening of the day +before the belt of condensation arrives.</p> + +<p>3. Belt of condensation, with or without rain or<span class="pagenum"><a name="Page_327" id="Page_327">[Pg 327]</a></span> showers, with the +easterly wind blowing axially, if the condensation is heavy and the belt +wide; westerly if the condensation is feeble or the belt narrow—the +clouds moving about E. N. E.</p> + +<p>4. Cooler air, light N. W. in summer, heavy N. W. in autumn, winter, and +spring.</p> + +<p>And, the next period—</p> + +<p>5. Still warm weather or light airs.</p> + +<p>6. Southerly wind, fresh.</p> + +<p>7. Belt of condensation.</p> + +<p>8. Cool northerly wind.</p> + +<p>And so on, successively, unless broken in upon by some other class.</p> + +<p>Sometimes these periods are exceedingly regular, at other times the other +classes prevail. I have much reason to believe that this is the <i>normal, +periodic</i> provision for condensation of our portion of the northern +hemisphere, and probably of every other where rain falls regularly in the +summer season, and that the other classes are exceptions, as the +hurricanes are exceptions to the normal condition of the weather every +where. Perhaps in some seasons, during the northern transit, the +exceptions may equal the rule, but I do not now remember such a season. In +other years nearly all the storms are of this character. Thus, Dr. +Hildreth (in Silliman’s Journal for 1827), speaking of the year 1826, in a +note to his register of that year, says: “There have been, this year, an +unusual number of winds from N. or N. W. Nearly every rain the past summer +has been followed with winds from the northward, when, in many previous +summers, the wind continued to the southward after<span class="pagenum"><a name="Page_328" id="Page_328">[Pg 328]</a></span> rain.” The immediate +occurrence of northerly wind after the passage of the belt of +condensation, is a peculiar feature of this class of storms.</p> + +<p>As this also will be new, and is of great practical interest, I shall be +pardoned for referring to other evidence. Bermuda is in latitude 32° +north. In the summer season they are within the range of the Calms of +Cancer, as Lieutenant Maury terms them, and not subject to storms. From +November to May, inclusive, they have successions of revolving wind. +Colonel Reid gave them much attention, and studied them barometrically: +that is, he studied the changes of the wind during the successive periodic +depressions. He found them revolving like ours, and hence inferred the +truth of the gyratory theory in relation to all winds. But it is perfectly +evident the same polar belts which pass over us reach them during the +southern transit. The precedent southerly wind, the <i>central +condensation</i>, the appearance of lightning, and the rotation of the wind +by both the east and west, but most frequently by west, are the same. In +his chapter on observations at the Bermudas, he gives us many examples. +Probably the existence of the Gulf Stream to the west and north has a +modifying influence upon them, and their action becomes less intense in +that latitude, but they are very similar. I copy a record of the weather, +for a month, which may be found on pages 252, 253, and 254, and a portion +of his remarks:</p> + +<div class="blockquot"><p>“The month of December, 1839, presents a continual succession of +revolving winds passing over the Bermudas, with scarcely an +<span class="pagenum"><a name="Page_329" id="Page_329">[Pg 329]</a></span>irregularity, as regards the fall and rise of the barometer +accompanying the veering of the wind. One, however, occurred on the +10th and 11th. The S. W. wind abated, and changed to W. N. W., with +the barometer still falling. But in the column of remarks it is noted +that there was lightning seen in the N. and N. W., from 7 <span class="smcaplc">P.M.</span>, +during the night. This irregularity may, therefore, have been +occasioned by a gale passing over the banks of Newfoundland, +influencing the direction of the wind at Bermuda.</p></div> + +<p class="center">“REVOLVING WINDS.</p> + +<table border="0" cellpadding="0" cellspacing="0" summary="winds"> +<tr><td class="btrl" align="center">Date.</td> + <td class="btr" align="center">Hour.</td> + <td class="btr" align="center">Direction of<br />Wind.</td> + <td class="btr" align="center">Wind’s<br />Force.</td> + <td class="btr" align="center">Weather.</td> + <td class="btr" align="center">Bar.</td> + <td class="btr" align="center">Ther.</td></tr> +<tr><td class="btrl">1839.</td> + <td class="btr"> </td> + <td class="btr"> </td> + <td class="btr"> </td> + <td class="btr"> </td> + <td class="btr"> </td> + <td class="btr"> </td></tr> +<tr><td class="blr">Nov. 30</td> + <td class="br" align="center">Midnight.</td> + <td class="br" align="center">S. S. E.</td> + <td class="br" align="center">1</td> + <td class="br" align="center">b. c.</td> + <td class="br"><span style="margin-left: .5em;">30·06</span></td> + <td class="br" align="center">65</td></tr> +<tr><td class="blr">Dec. <span style="margin-left: .5em;">1</span></td> + <td class="br" align="center">Noon.</td> + <td class="br" align="center">S. S. W.</td> + <td class="br" align="center">3</td> + <td class="br" align="center">b. c.</td> + <td class="br"><span style="margin-left: .5em;">30·07</span></td> + <td class="br" align="center">71</td></tr> +<tr><td class="blr"><span style="margin-left: 2.5em;">2</span></td> + <td class="br" align="center">"</td> + <td class="br" align="center">S. W.</td> + <td class="br" align="center">5</td> + <td class="br" align="center">g. m. q.</td> + <td class="br"><span style="margin-left: .5em;">29·86</span></td> + <td class="br" align="center">70</td></tr> +<tr><td class="blr"><span style="margin-left: 2.5em;">3</span></td> + <td class="br" align="center">"</td> + <td class="br" align="center">S. S. W.</td> + <td class="br" align="center">3</td> + <td class="br" align="center">g. c.</td> + <td class="br"><span style="margin-left: .5em;">29·76</span></td> + <td class="br" align="center">"</td></tr> +<tr><td class="blr"><span style="margin-left: 2.5em;">4</span></td> + <td class="br" align="center">"</td> + <td class="br" align="center">S. W.</td> + <td class="br" align="center">6</td> + <td class="br" align="center">g. m. r.</td> + <td class="br"><span style="margin-left: .5em;">29·62</span></td> + <td class="br" align="center">68</td></tr> +<tr><td class="blr"><span style="margin-left: 2.5em;">5</span></td> + <td class="br" align="center">"</td> + <td class="br" align="center">W. N. W.</td> + <td class="br" align="center">5</td> + <td class="br" align="center">p. q.</td> + <td class="br"><span style="margin-left: .5em;">29·56</span></td> + <td class="br" align="center">"</td></tr> +<tr><td class="blr"><span style="margin-left: 2.5em;">6</span></td> + <td class="br" align="center">"</td> + <td class="br" align="center">N. W.</td> + <td class="br" align="center">6</td> + <td class="br" align="center">p. q.</td> + <td class="br">*29·55</td> + <td class="br" align="center">"</td></tr> +<tr><td class="blr"><span style="margin-left: 2.5em;">7</span></td> + <td class="br" align="center">"</td> + <td class="br" align="center">N. N. W.</td> + <td class="br" align="center">5</td> + <td class="br" align="center">b. c.</td> + <td class="br"><span style="margin-left: .5em;">29·78</span></td> + <td class="br" align="center">70</td></tr> +<tr><td class="blr"><span style="margin-left: 2.5em;">"</span></td> + <td class="br" align="center">Midnight.</td> + <td class="br" align="center">N. N. W.</td> + <td class="br" align="center">3</td> + <td class="br" align="center">b. c.</td> + <td class="br"><span style="margin-left: .5em;">29·89</span></td> + <td class="br" align="center">68</td></tr> +<tr><td class="blr"><span style="margin-left: 2.5em;">8</span></td> + <td class="br" align="center">Noon.</td> + <td class="br" align="center">W. N. W.</td> + <td class="br" align="center">2</td> + <td class="br" align="center">b. c.</td> + <td class="br"><span style="margin-left: .5em;">29·82</span></td> + <td class="br" align="center">71</td></tr> +<tr><td class="blr"><span style="margin-left: 2.5em;">9</span></td> + <td class="br" align="center">"</td> + <td class="br" align="center">S. S. W.</td> + <td class="br" align="center">5</td> + <td class="br" align="center">p. q.</td> + <td class="br"><span style="margin-left: .5em;">29·84</span></td> + <td class="br" align="center">70</td></tr> +<tr><td class="blr"><span style="margin-left: 2em;">10</span></td> + <td class="br" align="center">"</td> + <td class="br" align="center">S. W.</td> + <td class="br" align="center">2</td> + <td class="br" align="center">b. c.</td> + <td class="br"><span style="margin-left: .5em;">29·96</span></td> + <td class="br" align="center">"</td></tr> +<tr><td class="blr"><span style="margin-left: 2em;">11</span></td> + <td class="br" align="center">"</td> + <td class="br" align="center">W. N. W.</td> + <td class="br" align="center">6</td> + <td class="br" align="center">b. c. m.</td> + <td class="br">*29·88</td> + <td class="br" align="center">68</td></tr> +<tr><td class="blr"><span style="margin-left: 2em;">12</span></td> + <td class="br" align="center">"</td> + <td class="br" align="center">S. S. W.</td> + <td class="br" align="center">"</td> + <td class="br" align="center">b. v.</td> + <td class="br"><span style="margin-left: .5em;">29·99</span></td> + <td class="br" align="center">69</td></tr> +<tr><td class="blr"><span style="margin-left: 2em;">13</span></td> + <td class="br" align="center">"</td> + <td class="br" align="center">N. N. by W.</td> + <td class="br" align="center">"</td> + <td class="br" align="center">b. v.</td> + <td class="br"><span style="margin-left: .5em;">30·01</span></td> + <td class="br" align="center">66</td></tr> +<tr><td class="blr"><span style="margin-left: 2em;">14</span></td> + <td class="br" align="center">"</td> + <td class="br" align="center">N. N. W.</td> + <td class="br" align="center">5</td> + <td class="br" align="center">b. c. v.</td> + <td class="br"><span style="margin-left: .5em;">30·06</span></td> + <td class="br" align="center">64</td></tr> +<tr><td class="blr"><span style="margin-left: 2.5em;">"</span></td> + <td class="br" align="center">Midnight.</td> + <td class="br" align="center">N. W.</td> + <td class="br" align="center">2</td> + <td class="br" align="center">b. c. p.</td> + <td class="br"><span style="margin-left: .5em;">30·05</span></td> + <td class="br" align="center">63</td></tr> +<tr><td class="blr"><span style="margin-left: 2em;">15</span></td> + <td class="br" align="center">Noon.</td> + <td class="br" align="center">S. W. by S.</td> + <td class="br" align="center">6</td> + <td class="br" align="center">g. m. r.</td> + <td class="br"><span style="margin-left: .5em;">29·72</span></td> + <td class="br" align="center">65</td></tr> +<tr><td class="blr"><span style="margin-left: 2.5em;">"</span></td> + <td class="br" align="center">P.M. 2</td> + <td class="br" align="center">S. S. W.</td> + <td class="br" align="center">7</td> + <td class="br" align="center">m. q. r.</td> + <td class="br"><span style="margin-left: .5em;">29·92</span></td> + <td class="br" align="center">64</td></tr> +<tr><td class="blr"><span style="margin-left: 2.5em;">"</span></td> + <td class="br" align="center"><span style="margin-left: .5em;">"</span> <span style="margin-left: 1em;">4</span></td> + <td class="br" align="center">S. S. W.</td> + <td class="br" align="center">"</td> + <td class="br" align="center">g. m. q. r.</td> + <td class="br"><span style="margin-left: .5em;">29·55</span></td> + <td class="br" align="center">"</td></tr> +<tr><td class="blr"><span style="margin-left: 2.5em;">"</span></td> + <td class="br" align="center"><span style="margin-left: .5em;">"</span> <span style="margin-left: 1em;">6</span></td> + <td class="br" align="center">W. S. W.</td> + <td class="br" align="center">"</td> + <td class="br" align="center">q. w.</td> + <td class="br">*29·53</td> + <td class="br" align="center">"</td></tr> +<tr><td class="blr"><span style="margin-left: 2.5em;">"</span></td> + <td class="br" align="center"><span style="margin-left: .5em;">"</span> <span style="margin-left: 1em;">8</span></td> + <td class="br" align="center">N. W.</td> + <td class="br" align="center">6</td> + <td class="br" align="center">b. c. q.</td> + <td class="br"><span style="margin-left: .5em;">29·54</span></td> + <td class="br" align="center">"</td></tr> +<tr><td class="blr"><span style="margin-left: 2.5em;">"</span></td> + <td class="br" align="center"><span style="margin-left: .5em;">"</span> <span style="margin-left: .5em;">10</span></td> + <td class="br" align="center">N. N. W.</td> + <td class="br" align="center">"</td> + <td class="br" align="center">b. c.</td> + <td class="br"><span style="margin-left: .5em;">29·55</span></td> + <td class="br" align="center">"</td></tr> +<tr><td class="blr"><span style="margin-left: 2em;">16</span></td> + <td class="br" align="center">Noon.</td> + <td class="br" align="center">N. W.</td> + <td class="br" align="center">7</td> + <td class="br" align="center">b. c. m.</td> + <td class="br"><span style="margin-left: .5em;">29·53</span></td> + <td class="br" align="center">62</td></tr> +<tr><td class="blr"><span style="margin-left: 2em;">17</span></td> + <td class="br" align="center">"</td> + <td class="br" align="center">N. W. by N.</td> + <td class="br" align="center">"</td> + <td class="br" align="center">p. q.</td> + <td class="br"><span style="margin-left: .5em;">29·67</span></td> + <td class="br" align="center">60</td></tr> +<tr><td class="blr"><span style="margin-left: 2em;">18</span></td> + <td class="br" align="center">"</td> + <td class="br" align="center">N. W.</td> + <td class="br" align="center">6</td> + <td class="br" align="center">c. q.</td> + <td class="br"><span style="margin-left: .5em;">29·86</span></td> + <td class="br" align="center">"</td></tr> +<tr><td class="blr"><span style="margin-left: 2em;">19</span></td> + <td class="br" align="center">"</td> + <td class="br" align="center">N. W. by N.</td> + <td class="br" align="center">7</td> + <td class="br" align="center">m. q. r.</td> + <td class="br">*29·73</td> + <td class="br" align="center">59</td></tr> +<tr><td class="blr"><span style="margin-left: 2em;">20</span></td> + <td class="br" align="center">"</td> + <td class="br" align="center">N. N. W.</td> + <td class="br" align="center">"</td> + <td class="br" align="center">p. q. c.</td> + <td class="br"><span style="margin-left: .5em;">29·89</span></td> + <td class="br" align="center">58</td></tr> +<tr><td class="blr"><span style="margin-left: 2em;">21</span></td> + <td class="br" align="center">"</td> + <td class="br" align="center">N. W. by N.</td> + <td class="br" align="center">6</td> + <td class="br" align="center">c. q.</td> + <td class="br"><span style="margin-left: .5em;">29·96</span></td> + <td class="br" align="center">56</td></tr> +<tr><td class="blr"><span style="margin-left: 2.5em;">"</span></td> + <td class="br" align="center">Midnight.</td> + <td class="br" align="center">S. W.</td> + <td class="br" align="center">1</td> + <td class="br" align="center">b. c.</td> + <td class="br"><span style="margin-left: .5em;">29·95</span></td> + <td class="br" align="center">55</td></tr> +<tr><td class="blr"><span style="margin-left: 2em;">22</span></td> + <td class="br" align="center">Dawn.</td> + <td class="br" align="center">——</td> + <td class="br" align="center">0</td> + <td class="br" align="center"> </td> + <td class="br"> </td> + <td class="br" align="center"> </td></tr> +<tr><td class="blr"><span style="margin-left: 2.5em;">"</span></td> + <td class="br" align="center">Noon.</td> + <td class="br" align="center">S. S. W.</td> + <td class="br" align="center">5</td> + <td class="br" align="center">g. m.</td> + <td class="br"><span style="margin-left: .5em;">29·83</span></td> + <td class="br" align="center">56</td></tr> +<tr><td class="blr"><span style="margin-left: 2.5em;">"</span></td> + <td class="br" align="center">P.M. 4</td> + <td class="br" align="center">S.</td> + <td class="br" align="center">7</td> + <td class="br" align="center">g. m.</td> + <td class="br"><span style="margin-left: .5em;">29·79</span></td> + <td class="br" align="center">"</td></tr> +<tr><td class="blr"><span style="margin-left: 2.5em;">"</span></td> + <td class="br" align="center"><span style="margin-left: .5em;">"</span> <span style="margin-left: 1em;">6</span></td> + <td class="br" align="center">S. S. E.</td> + <td class="br" align="center">"</td> + <td class="br" align="center">g. m. r.</td> + <td class="br"><span style="margin-left: .5em;">29·61</span></td> + <td class="br" align="center">"</td></tr> +<tr><td class="blr"><span style="margin-left: 2.5em;">"</span></td> + <td class="br" align="center"><span style="margin-left: .5em;">"</span> <span style="margin-left: 1em;">8</span></td> + <td class="br" align="center">S. S. E.</td> + <td class="br" align="center">"</td> + <td class="br" align="center">w. r.</td> + <td class="br"><span style="margin-left: .5em;">29·52</span></td> + <td class="br" align="center">"</td></tr> +<tr><td class="blr"><span style="margin-left: 2.5em;">"</span></td> + <td class="br" align="center"><span style="margin-left: .5em;">"</span> <span style="margin-left: .5em;">10</span></td> + <td class="br" align="center">S. E.</td> + <td class="br" align="center">"</td> + <td class="br" align="center">m. w. r.</td> + <td class="br"><span style="margin-left: .5em;">29·48</span></td> + <td class="br" align="center">"</td></tr> +<tr><td class="blr"><span style="margin-left: 2em;">23</span></td> + <td class="br" align="center">Noon.</td> + <td class="br" align="center">S. W.</td> + <td class="br" align="center">6</td> + <td class="br" align="center">b. c. m.</td> + <td class="br">*29·44</td> + <td class="br" align="center">57</td></tr> +<tr><td class="blr"><span style="margin-left: 2em;">24</span></td> + <td class="br" align="center">"</td> + <td class="br" align="center">W. N. W.</td> + <td class="br" align="center">"</td> + <td class="br" align="center">b. m.</td> + <td class="br"><span style="margin-left: .5em;">29·71</span></td> + <td class="br" align="center">59</td></tr> +<tr><td class="blr"><span style="margin-left: 2em;">25</span></td> + <td class="br" align="center">"</td> + <td class="br" align="center">W. N. W.</td> + <td class="br" align="center">5</td> + <td class="br" align="center">b. c.</td> + <td class="br"><span style="margin-left: .5em;">29·88</span></td> + <td class="br" align="center">56</td></tr> +<tr><td class="blr"><span style="margin-left: 2em;">26</span></td> + <td class="br" align="center">"</td> + <td class="br" align="center">N.</td> + <td class="br" align="center">3</td> + <td class="br" align="center">c.</td> + <td class="br"><span style="margin-left: .5em;">30·09</span></td> + <td class="br" align="center">62</td></tr> +<tr><td class="blr"><span style="margin-left: 2em;">27</span></td> + <td class="br" align="center">"</td> + <td class="br" align="center">S. E.</td> + <td class="br" align="center">5</td> + <td class="br" align="center">c. q. r.</td> + <td class="br"><span style="margin-left: .5em;">30·07</span></td> + <td class="br" align="center">61</td></tr> +<tr><td class="blr"><span style="margin-left: 2em;">28</span></td> + <td class="br" align="center">"</td> + <td class="br" align="center">S. W.</td> + <td class="br" align="center">6</td> + <td class="br" align="center">c. q.</td> + <td class="br"><span style="margin-left: .5em;">29·88</span></td> + <td class="br" align="center">66</td></tr> +<tr><td class="blr"><span style="margin-left: 2.5em;">"</span></td> + <td class="br" align="center">Midnight.</td> + <td class="br" align="center">S. S. W.</td> + <td class="br" align="center">"</td> + <td class="br" align="center">b. c.</td> + <td class="br"><span style="margin-left: .5em;">29·76</span></td> + <td class="br" align="center">65</td></tr> +<tr><td class="blr"><span style="margin-left: 2em;">29</span></td> + <td class="br" align="center">Noon.</td> + <td class="br" align="center">S. W.</td> + <td class="br" align="center">7</td> + <td class="br" align="center">c. b.</td> + <td class="br">*29·48</td> + <td class="br" align="center">64</td></tr> +<tr><td class="blr"><span style="margin-left: 2em;">30</span></td> + <td class="br" align="center">"</td> + <td class="br" align="center">W. N. W.</td> + <td class="br" align="center">6</td> + <td class="br" align="center">b. c. q.</td> + <td class="br"><span style="margin-left: .5em;">29·83</span></td> + <td class="br" align="center">55</td></tr> +<tr><td class="bblr"><span style="margin-left: 2em;">31</span></td> + <td class="bbr" align="center">"</td> + <td class="bbr" align="center">N. W.</td> + <td class="bbr" align="center">5</td> + <td class="bbr" align="center">b. c.</td> + <td class="bbr"><span style="margin-left: .5em;">30·12</span></td> + <td class="bbr" align="center">58</td></tr></table> + +<p> </p> +<div class="blockquot"><p class="center"><span class="pagenum"><a name="Page_330" id="Page_330">[Pg 330]</a></span>“<i>Remark printed in the Register.</i></p> + +<p>“The changes of the wind during the December gales have been nearly +the same in all: <i>i. e.</i>, commencing with a southerly wind at first, +the wind has veered by the west, toward the north-west, sometimes +ending as far round as N. N. W.”</p></div> + +<p>These extracts show the passage of several successive belts, each with the +phenomena in regular order.</p> + +<p>The first commences with blue sky and detached clouds, barometer up, +thermometer down to 65°, and nearly calm, on the 30th of November.</p> + +<p>Dec. 1 (at noon). Wind freshens from S. S. W.; thermometer rises; +barometer still up.</p> + +<p>Dec. 2. Barometer has fallen; thermometer up; wind increasing from S. W., +with gloomy, squally appearance.</p> + +<p>Dec. 3. Wind S. S. W.; barometer slowly falling; thermometer slightly.</p> + +<p>Dec. 4. Wind fresh; S. W.; condensation and rain has reached them, and it +carries barometer and thermometer down.</p> + +<p>Dec. 5. Wind shifting by the west, and squally.</p> + +<p>Dec. 6. Winds gets N. W.; blows fresh; barometer at its minimum, probably +at the time of the change of wind, although the register does not show the +precise time.</p> + +<p>Dec. 7. Wind N. N. W.; blue sky and detached clouds (N. W. scud), cleared +off; barometer elevated by the N. W. wind, from 29.55 to 29.78. Midnight: +blue sky; detached clouds (N. W. scud probably); barometer up to 29.89; +thermometer fallen, from the cooler character of the northerly wind.</p> + +<p><span class="pagenum"><a name="Page_331" id="Page_331">[Pg 331]</a></span>Dec. 8. Wind having lulled as a northerly wind has got round to S. W. +again; thermometer up; barometer falling, and another belt approaching, +and so on.</p> + +<p>The first and last part of December show each two regular occurrences of +substantially the same phenomena. The middle is somewhat more irregular.</p> + +<p>There were five distinctly-marked periods, and one squally, long-continued +period, with a slight tendency to condensation, and a slight fall of +barometer and rain on the 19th (N. W. squall probably), but not sufficient +to reverse the wind to the south. In Colonel Reid’s opinion there were +five revolving gales which passed over Bermuda during the month. In my +opinion, there were five perfect polar waves of condensation, and one +imperfect one, with as many successive southerly winds preceding the +condensation, with or without rain in the center, followed by as many cold +N. W. or N. N. W. winds, with squalls, in the rear, about five days apart. +(See <a href="#Page_329">the * in the barometric column</a>.)</p> + +<p><i>We are at issue.</i> Let the question be determined by <i>actual observation</i>, +and not by <i>speculation</i>. It is of fundamental and exceeding importance to +the science.</p> + +<p>Now, let us take a month in summer, from the observations of Mr. Bassnett, +at Ottawa. Here the climate differs somewhat from that east of the +Alleghanies; the magnetic intensity is greater, and the action more +violent and irregular. That part of the country, it should be remembered, +has a greater fall of rain in summer, for reasons we have stated, and +those periodic revolutions are more frequent.</p> + +<div class="blockquot"><p><span class="pagenum"><a name="Page_332" id="Page_332">[Pg 332]</a></span>“A brief abstract from a journal of the weather for one sidereal +period of the moon, in 1853.</p> + +<p>“<i>June</i> 21st. Fine clear morning (S. fresh): noon very warm 88°; 4 +<span class="smcaplc">P.M.</span>, plumous <i>cirri in south</i>; ends clear.</p> + +<p>“22d. Hazy morning (S. very fresh) arch of cirrus in west; 2 <span class="smcaplc">P.M.</span>, +black in W. N. W.; 3 <span class="smcaplc">P.M.</span>, overcast and rainy; 4 <span class="smcaplc">P.M.</span>, a heavy gust +from south; 4.30 <span class="smcaplc">P.M.</span>, blowing furiously (S. by W.); 5 <span class="smcaplc">P.M.</span>, +tremendous squall, uprooting trees and scattering chimneys; 6 <span class="smcaplc">P.M.</span>, +more moderate (W.).</p> + +<p>“23d. Clearing up (N. W.); 8 <span class="smcaplc">A.M.</span>, quite clear; 11 <span class="smcaplc">A.M.</span>, bands of +mottled cirri pointing N. E. and S. W., ends cold (W. N. W.); the +cirri seem to rotate from left to right, or with the sun.</p> + +<p>“24th. Fine clear, cool day, begins and ends (N. W.).</p> + +<p>“25th. Clear morning (N. W. light); 2 <span class="smcaplc">P.M.</span> (E.), calm; tufts of +tangled cirri in north, intermixed with radiating streaks, all +passing eastward; ends clear.</p> + +<p>“26th. Hazy morning (S. E.), cloudy; noon, a heavy, windy-looking +bank in north (S. fresh), with dense cirrus fringe above, on its +upper edge; clear in S.</p> + +<p>“27th. Clear, warm (W.); bank in north; noon bank covered all the +northern sky, and fresh breeze; 10 <span class="smcaplc">P.M.</span>, a few flashes to the +northward.</p> + +<p>“28th. Uniform dense cirro-stratus (S. fresh); noon showers all +round; 2 <span class="smcaplc">P.M.</span>, a heavy squall of wind, with thunder and rain (S. W. +to N. W.); 8 <span class="smcaplc">P.M.</span>, a line of heavy cumuli in south; 8.30 <span class="smcaplc">P.M.</span>, a very +bright and high cumulus in S. W., protruding through a layer of dark +stratus; 8.50 <span class="smcaplc">P.M.</span>, the cloud bearing E. by S., with three rays of +electric light.</p> + +<p>“29th. A stationary stratus over all (S. W. light); clear at night, +but distant lightning in S.</p> + +<p>“30th. Stratus clouds (N. E. almost calm); 8 <span class="smcaplc">A.M.</span>, raining gently; 3 +<span class="smcaplc">P.M.</span>, stratus passing off to S.; 8 <span class="smcaplc">P.M.</span>, clear, pleasant.</p> + +<p>“<i>July</i> 1st. Fine and clear; 8 <span class="smcaplc">A.M.</span>, cirrus in sheets, curls, wisps, +and gauzy wreaths, with patches beneath of darker shade, all nearly +motionless; close and warm (N. E.); a long, low bank of haze in S., +with one large cumulus in S. W., but very distant.</p> + +<p>“2d. At 5 <span class="smcaplc">A.M.</span>, overcast generally, with hazy clouds and fog of +prismatic shades, chiefly greenish-yellow; 7 <span class="smcaplc">A.M.</span> (S. S. E. +freshening), thick in W.; 8 <span class="smcaplc">A.M.</span> (S. fresh), much cirrus, thick and +gloomy; 9 <span class="smcaplc">A.M.</span>, a clap of thunder, and clouds hurrying to N.; a +reddish haze all around; at noon the margin of a line of +yellowish-red cumuli just visible above a gloomy-looking bank of haze +in N. N. W. (S. very fresh); warm, 86°; more cumuli in N. W.; the +whole line of<span class="pagenum"><a name="Page_333" id="Page_333">[Pg 333]</a></span> cumuli N. are separated from the clouds south by a +clearer space. These clouds are borne rapidly past the zenith, but +never get into the clear space—they seem to melt or to be turned off +N. E. The cumuli in N. and N. W., slowly spreading E. and S.; 3 <span class="smcaplc">P.M.</span>, +the bank hidden by small cumuli; 4 <span class="smcaplc">P.M.</span>, very thick in north, +magnificent cumuli visible sometimes through the breaks, and beyond +them a dark, watery back-ground (S. strong); 4.30 <span class="smcaplc">P.M.</span>, wind round to +N. W. in a severe squall; 5 <span class="smcaplc">P.M.</span>, heavy rain, with thunder, etc.—all +this time there is a bright sky in the south visible through the rain +15° high; 7 <span class="smcaplc">P.M.</span>, clearing (S. W. mod.).</p> + +<p>“3d. Very fine and clear (N. W.); noon, a line of large cumuli in N., +and dark lines of stratus below, the cumuli moving eastward; 6 <span class="smcaplc">P.M.</span>, +their altitude 2° 40′. Velocity, 1° per minute; 9 <span class="smcaplc">P.M.</span>, much +lightning in the bank north.</p> + +<p>“4th. 6 <span class="smcaplc">A.M.</span>, a line of small cumulo-stratus, extending east and +west, with a clear horizon north and south 10° high. This band seems +to have been thrown off by the central yesterday, as it moves slowly +south, preserving its parallelism, although the clouds composing it +move eastward. Fine and cool all day (N. W. mod.)—lightning in N.</p> + +<p>“5th. Cloudy (N. almost calm), thick in E., clear in W.; same all +day.</p> + +<p>“6th. Fine and clear (E. light); small cumuli at noon; clear night.</p> + +<p>“7th. Warm (S. E. light); cirrus bank N. W.; noon (S.) thickening in +N.; 6 <span class="smcaplc">P.M.</span>, hazy but fine; 8 <span class="smcaplc">P.M.</span>, lightning in N.; 10 <span class="smcaplc">P.M.</span>, the +lightning shows a heavy line of cumuli along the northern horizon; +calm and very dark, and incessant lightning in N.</p> + +<p>“8th. Last night after midnight commencing raining, slowly and +steadily, but leaving a line of lighter sky south; much lightning all +night, but little thunder.</p> + +<p>“8th. 6 <span class="smcaplc">A.M.</span>, very low scud (500 feet high) driving south, still calm +below (N. light); 10 <span class="smcaplc">A.M.</span>, clearing a little; a bank north, with +cirrus spreading south; same all day; 9 <span class="smcaplc">P.M.</span>, wind freshening (N. +stormy); heavy cumuli visible in S.; 10.30 <span class="smcaplc">P.M.</span>, quite clear, but a +dense watery haze obscuring the stars; 12 <span class="smcaplc">P.M.</span>, again overcast; much +lightning in S. and N. W.</p> + +<p>“9th. Last night (2 <span class="smcaplc">A.M.</span> of 9th) squall from N. W. very black; 4 +<span class="smcaplc">A.M.</span>, still raining and blowing hard, the sky a perfect blaze, but +very few flashes reach the ground; 7 <span class="smcaplc">A.M.</span>, raining hard; 8 <span class="smcaplc">A.M.</span> (N. +W. strong); a constant roll of thunder; noon (N. E.); 2 <span class="smcaplc">P.M.</span> (N.); 4 +<span class="smcaplc">P.M.</span>, clearing; 8 <span class="smcaplc">P.M.</span>, a line of heavy cumuli in S., but clear in N. +W., N., and N. E.</p> + +<p>“10th. 3 <span class="smcaplc">A.M.</span>, Overcast, and much lightning in south (N. mod.);<span class="pagenum"><a name="Page_334" id="Page_334">[Pg 334]</a></span> 7 +<span class="smcaplc">A.M.</span>, clear except in south; 6 <span class="smcaplc">P.M.</span> (E.); 10 <span class="smcaplc">P.M.</span>, lightning south; +11 <span class="smcaplc">P.M.</span>, auroral rays long, but faint, converging to a point between +Epsilon Virginis and Denebola, in west; low down in west, thick with +haze; on the north the rays converged to a point still lower; +lightning still visible in south. This is an aurora in the west.</p> + +<p>“11th. Fine, clear morning (N. E.); same all day; no lightning +visible to-night, but a bank of clouds low down in south, 2° high, +and streaks of dark stratus below the upper margin.</p> + +<p>“12th. Fine and clear (N. E.); noon, a well-defined arch in S. W., +rising slowly; the bank yellowish, with prismatic shades of +greenish-yellow on its borders. This is the O. A. At 6 <span class="smcaplc">P.M.</span>, the bank +spreading to the northward. At 9 <span class="smcaplc">P.M.</span>, thick bank of haze in north, +with bright auroral margin; one heavy pyramid of light passed through +Cassiopeia, traveling <i>westward</i> 1½° per minute. This moves to the +other side of the pole, but not more inclined toward it than is due +to prospective, if the shaft is very long; 11.10 <span class="smcaplc">P.M.</span>, saw a mass of +light more diffuse due east, reaching to <i>Markab</i>, then on the prime +vertical. It appears evident this is seen in profile, as it inclines +downward at an angle of 10° or 12° from the perpendicular. It does +not seem very distant. 12 <span class="smcaplc">P.M.</span>, the aurora still bright, but the +brightest part is now west of the pole, before it was east.</p> + +<p>“13th. 6 <span class="smcaplc">A.M.</span>, clear, east and north; bank of cirrus in N. W., <i>i. +e.</i>, from N. N. E. to W. by S.; irregular branches of cirrus clouds, +reaching almost to south-eastern horizon; wind changed (S. E. fresh); +8 <span class="smcaplc">A.M.</span>, the sky a perfect picture; heavy regular shafts of dense +cirrus radiating all around, and diverging from a thick nucleus in +north-west, the spaces between being of clear, blue sky. The shafts +are rotating from north to south, the nucleus advancing eastward.</p> + +<p>“At noon (same day), getting thicker (S. E. very fresh); 6 <span class="smcaplc">P.M.</span>, moon +on meridian, a prismatic gloom in south, and very thick stratus of +all shades; 9 <span class="smcaplc">P.M.</span>, very gloomy; wind stronger (S. E.); 10 <span class="smcaplc">P.M.</span>, very +black in south, and overcast generally.</p> + +<p>“14th. Last night, above 12 <span class="smcaplc">P.M.</span>, commenced raining; 3 <span class="smcaplc">A.M.</span>, rained +steadily; 7 <span class="smcaplc">A.M.</span>, same weather; 8.20 <span class="smcaplc">A.M.</span>, a line of low storm-cloud, +or scud, showing very sharp and white on the dark back-ground all +along the southern sky. This line continues until noon, about 10° at +the highest, showing the northern boundary of the storm to the +southward; 8 <span class="smcaplc">P.M.</span>, same bank visible, although in rapid motion +eastward; same time clear overhead, with cirrus fringe pointing north +from the bank; much lightning in south (W. fresh); so ends.</p> + +<p>“15th. Last night a black squall from N. W. passed south without +rain; at 3 <span class="smcaplc">A.M.</span>, clear above but, very black in south (calm below all +the time); 9 <span class="smcaplc">A.M.</span>, the bank in south again throwing off rays of cirri +in a well-defined arch, whose vortex is south; these pass east, but<span class="pagenum"><a name="Page_335" id="Page_335">[Pg 335]</a></span> +continue to form and preserve their linear direction to the north; no +lightning in south to-night.</p> + +<p>“16th. Clear all day, without a stain, and calm.</p> + +<p>“17th. Fine and clear (N. E. light); 6 <span class="smcaplc">P.M.</span>, calm.</p> + +<p>“18th. Fair and cloudy (N. E. light); 6 <span class="smcaplc">P.M.</span>, calm.</p> + +<p>“19th. Fine and clear (N. fresh); I. V. visible in S. W.</p> + +<p>“20th. 8 <span class="smcaplc">A.M.</span>, bank in N. W., with beautiful cirrus radiations; 10 +<span class="smcaplc">A.M.</span>, getting thick, with dense plates of cream-colored cirrus +visible through the breaks; gloomy looking all day (N. E. light).”</p></div> + +<p>The letters in a parenthesis signify the direction of the wind.</p> + +<p>During this month there were three distinctly marked periods of belts of +showers, preceded by “fresh” or “strong” south wind, and followed by the +N. W. There was a period when a belt of less intense stratus, without much +wind, occurred (28th, 29th, and 30th of June). This was followed by a +distinct belt of showers and <i>fresh</i> S. wind, on the 2d of July, and by +the N. W. wind and clear weather, on the 3d.</p> + +<p>During the rest of July it was more irregular, with the exception of the +7th, 8th, and 9th, when another belt and revolution occurred.</p> + +<p>Now, these periods, when distinctly marked, exhibit the same succession of +phenomena—viz., elevation of temperature, fresh southerly wind, belt of +condensation, cumulus or stratus with cirrus running east, but extending +south, followed by N. W. wind, and clear, cold air. Can any one believe +they were successive rotary gales?</p> + +<p>I wish, in this connection, to make a suggestion to Lieutenant Maury and +others. The descriptions of M. Bassnett, although not perfect, are very +intelligible. He describes things as they were, and as they<span class="pagenum"><a name="Page_336" id="Page_336">[Pg 336]</a></span> should be +described. He distinguishes the clouds, and the scud, and other +appearances.</p> + +<p>But Colonel Reid’s descriptions are unmeaning and unintelligible. G. +M.—Gloomy, misty! Gloomy from what? fog, or stratus, or a stratum of +scud, or what? We can not know. Again, C. The table tells us this stands +for detached clouds. But of what kind? Cumulus, broken stratus, patches of +cirro-cumulus or cirro-stratus, or scud? All these, and indeed every kind +of cloud or fog formation, except low fog, may exist in detached portions.</p> + +<p>These abbreviations will not answer; they do not describe the weather. The +clouds must be studied and described. There is no difficulty in doing it. +Sailors will learn them very soon after their teachers have; and those who +teach them should see to it that the logs contain terms of description +which convey the meaning which may, and ought to be, conveyed. The use of +these indefinite terms can not be continued without culpability.</p> + +<p>Again, the observations of seamen off our coast are in accordance with the +progress of this class of storms on land, and prove that they continue S. +E. over the Atlantic, abating in action as they approach the tropics. +There is abundant evidence of this in the work of Colonel Reid, and the +charts of Lieutenant Maury, but I can not devote further space to them.</p> + +<p>The third class form in the counter-trade, over some portion of the +country, from excessive volume or action of the counter-trade, or local +magnetic activity, without coming from the tropics or being connected with +a regular polar wave of magnetic disturbance.</p> + +<p><span class="pagenum"><a name="Page_337" id="Page_337">[Pg 337]</a></span>The following diagram exhibits their form, progress, and accompanying +induced winds.</p> + +<p> </p> +<p class="center"><strong>Fig. 22.</strong></p> +<div class="figcenter"><img src="images/i0362.jpg" alt="" /></div> +<p> </p> + +<p>The gentle rains of spring, particularly April, and the moderate and +frequent snow-storms of winter, are often of this character; and so are +the heavy rains, which commence at the morning barometric minimum, rain +heavily through the forenoon, and light up near mid-day in the south, +followed by gentle, warm, S. W. winds. This class are more frequent in +some years than others—probably the early years of the decade, while +polar storms are, during the later ones. It is this class which have +<i>violent</i> easterly winds <i>in front</i>, and on the <i>south side</i>, with two or +more currents, and which Mr. Redfield has also supposed to be cyclones.</p> + +<p>The fourth class are isolated showers, occurring over particular +localities, or belts of drought and<span class="pagenum"><a name="Page_338" id="Page_338">[Pg 338]</a></span> showers alternating; sometimes a +general disposition to cloudy and showery weather for a longer or shorter +interval over the whole country; at others, limited to particular +localities in the course of the trade. Such a period occurred during the +wheat harvest of 1855. This class I attribute to a general increased +magnetic action, but it may be induced by an increased volume, or greater +south polar magnetic intensity of the counter-trade, exciting and +concentrating the regular currents of the field, and increasing their +activity and energy. These also often work off south gradually, and are +followed by a cold N. W. air for a day or two; showing a tendency, in the +excited magnetism, to pass as a wave toward the tropics.</p> + +<p>The following diagram will give some idea of this class:</p> + +<p> </p> +<p class="center"><strong>Fig. 23.</strong></p> +<div class="figcenter"><img src="images/i0363.jpg" alt="" /></div> +<p> </p> + +<p>There are sometimes very obvious local tendencies to precipitation over +portions adjoining an area affected<span class="pagenum"><a name="Page_339" id="Page_339">[Pg 339]</a></span> with drought, as there are other +magnetic irregularities over particular areas.</p> + +<p>All these classes of storms are variant in intensity. Sometimes the +general or local cloud-formation is weak, and does not produce +precipitation at all; so of that which extends southerly. Probably the +tropical storm are always sufficiently dense and active to precipitate. +Their action is often violent over particular localities, and hence the +more frequent occurrence of the tornado over the more intense area of +Ohio, and other portions of the west. All violent local storms are +doubtless owing to local magneto-electric activity.</p> + + +<p> </p><p> </p> +<hr style="width: 50%;" /> +<p><span class="pagenum"><a name="Page_340" id="Page_340">[Pg 340]</a></span></p> +<h2><a name="CHAPTER_XI" id="CHAPTER_XI"></a>CHAPTER XI.</h2> + +<p>The reader who has attentively perused and considered the facts stated, +and the principles deduced, in the preceding pages, and is ready to make a +practical application of them by careful observation, will have little +difficulty in understanding the varied atmospheric conditions; and will +soon be able to form a correct judgment of the immediate future of the +weather, so far as his limited horizon will permit.</p> + +<p>But there are other facts and considerations, not specifically alluded to, +which will materially aid him in his observations; and there is a degree +of philosophical truth in the proverbs and signs, which ancient popular +observation accumulated, and poetry and tradition have preserved, that +meteorologists have been slow to discover or admit, but which will be +obvious upon examination, and commend them to his attention.</p> + +<p>The classical reader is doubtless familiar with that part of the first +Georgic of Virgil, which contains a description of the signs indicative of +atmospheric changes. Much of it is beautifully poetic, and, if read in the +light of a correct philosophy, is equally truthful.</p> + +<p><span class="pagenum"><a name="Page_341" id="Page_341">[Pg 341]</a></span>I copy from a creditable translation, found in the first volume of +Howard’s “Climate of London”:</p> + +<p class="poem">“All that the genial year successive brings,<br /> +Showers, and the reign of heat, and freezing gales,<br /> +Appointed signs foreshow; the Sire of all<br /> +Decreed what signs the southern blast should bring,<br /> +Decreed the omens of the varying moon:<br /> +That hinds, observant of the approaching storm,<br /> +Might tend their herds more near the sheltering stall.”<br /> +<br /> +<br /> +<span style="margin-left: 2em;">PROGNOSTICS.—<i>1st. Of Wind.</i></span><br /> +<br /> +“When storms are brooding—in the leeward gulf<br /> +Dash the swell’d waves; the mighty mountains pour<br /> +A harsh, dull murmur; far along the beach<br /> +Rolls the deep rushing roar; the whispering grove<br /> +Betrays the gathering elemental strife.<br /> +Scarce will the billows spare the curved keel;<br /> +For swift from open sea the cormorants sweep,<br /> +With clamorous croak; the ocean-dwelling coot<br /> +Sports on the sand; the hern her marshy haunts<br /> +Deserting, soars the lofty clouds above;<br /> +And oft, when gales impend, the gliding star<br /> +Nightly descends athwart the spangled gloom,<br /> +And leaves its fire-wake glowing white behind.<br /> +Light chaff and leaflets flitting fill the air,<br /> +And sportive feathers circle on the lake.”<br /> +<br /> +<br /> +<span style="margin-left: 5em;"><i>2d. Of Rain.</i></span><br /> +<br /> +“But when grim Boreas thunders; when the East<br /> +And black-winged West, roll out the sonorous peal,<br /> +The teeming dikes o’erflow the wide champaign,<br /> +And seamen furl their dripping sails. The shower,<br /> +Forsooth, ne’er took the traveler unawares!<br /> +The soaring cranes descried it in the vale,<br /> +And shunn’d its coming; heifers gazed aloft,<br /> +With nostrils wide, drinking the fragrant gale;<br /> +Skimm’d the sagacious swallow round the lake,<br /> +And croaking frogs renew’d their old complaint.<br /> +<span style="margin-left: 1em;">Oft, too, the ant, from secret chambers, bears</span><br /> +<span class="pagenum"><a name="Page_342" id="Page_342">[Pg 342]</a></span>Her eggs—a cherished treasure—o’er the sand,<br /> +Along the narrow track her steps have worn.<br /> +High vaults the thirsty bow; in wide array<br /> +The clamorous rooks from every pasture rise<br /> +With serried wings. The varied sea-fowl tribes,<br /> +And those that in Cäyster’s meadows seek,<br /> +Amid the marshy pools, their skulking prey,<br /> +Fling the cool plenteous shower upon their wings,<br /> +Crouch to the coming wave, sail on its crest,<br /> +And idly wash their purity of plume.<br /> +The audacious crow, with loud voice, hails the rain<br /> +A lonesome wanderer on the thirsty sand.<br /> +Maidens that nightly toil the tangled fleece,<br /> +Divine the coming tempest; in the lamp<br /> +Crackles the oil; the gathering wick grows dim.”<br /> +<br /> +<br /> +<span style="margin-left: 4em;"><i>3d. Of Fair Weather.</i></span><br /> +<br /> +“Nor less, by sure prognostics, mayest thou learn<br /> +(When rain prevails), in prospect to behold<br /> +Warm suns, and cloudless heavens, around thee smile.<br /> +<span style="margin-left: 1em;">Brightly the stars shine forth; Cynthia no more</span><br /> +Glimmers obnoxious to her brother’s rays;<br /> +Nor fleecy clouds float lightly through the sky.<br /> +The chosen birds of Thetis, halcyons, now<br /> +Spread not their pinions on the sun-bright shore;<br /> +Nor swine the bands unloose, and toss the straw.<br /> +The clouds, descending, settle on the plain;<br /> +While owls forget to chant their evening song,<br /> +But watch the sunset from the topmost ridge.<br /> +The merlin swims the liquid sky, sublime,<br /> +While for the purple lock the lark atones:<br /> +Where she, with light wing, cleaves the yielding air,<br /> +Her shrieking fell pursuer follows fierce—<br /> +The dreaded merlin; where the merlin soars,<br /> +<i>Her</i> fugitive swift pinion cleaves the air.<br /> +And now, from throat compressed, the rook emits,<br /> +Treble or fourfold, his clear, piercing cry;<br /> +While oft amid their high and leafy roosts,<br /> +Bursts the responsive note from all the clan,<br /> +Thrill’d with unwonted rapture—oh! ’tis sweet,<br /> +When bright’ning hours allow, to seek again<br /> +Their tiny offspring, and their dulcet homes.<br /> +<span class="pagenum"><a name="Page_343" id="Page_343">[Pg 343]</a></span><span style="margin-left: 1em;">Yet deem I not, that heaven on them bestows</span><br /> +Foresight, or mind above their lowly fate;<br /> +But rather when the changeful climate veers,<br /> +Obsequious to the humor of the sky;<br /> +When the damp South condenses what was rare,<br /> +The dense relaxing—or the stringent North<br /> +Rolls back the genial showers, and rules in turn,<br /> +The varying impulse fluctuates in their breast:<br /> +Hence the full concert in the sprightly mead—<br /> +The bounding flock—the rook’s exulting cry.”<br /> +<br /> +<br /> +<span style="margin-left: 2em;"><i>4th. The Moon’s Aspects, etc.</i></span><br /> +<br /> +“Mark with attentive eye, the rapid sun—<br /> +The varying moon that rolls its monthly round;<br /> +So shalt thou count, not vainly, on the morn;<br /> +So the bland aspect of the tranquil night<br /> +Will ne’er beguile thee with insidious calm.<br /> +<span style="margin-left: 1em;">When Luna first her scatter’d fires recalls,</span><br /> +If with blunt horns she holds the dusky air,<br /> +Seamen and swains predict th’ abundant shower.<br /> +If rosy blushes tinge her maiden cheek,<br /> +Wind will arise: the golden Phœbe still<br /> +Glows with the wind. If (mark the ominous hour!)<br /> +The clear fourth night her lucid disk define,<br /> +That day, and all that thence successive spring,<br /> +E’en to the finished month, are calm and dry;<br /> +And grateful mariners redeem their vows<br /> +To Glaucus, Inöus, or the Nereid nymph.”<br /> +<br /> +<br /> +<span style="margin-left: 2em;"><i>5th. The Sun’s Aspects, etc.</i></span><br /> +<br /> +“The sun, too, rising, and at that still hour,<br /> +When sinks his tranquil beauty in the main,<br /> +Will give thee tokens; certain tokens all,<br /> +Both those that morning brings, and balmy eve.<br /> +When cloudy storms deform the rising orb,<br /> +Or streaks of vapor in the midst bisect,<br /> +Beware of showers, for then the blasting South<br /> +(Foe to the groves, to harvests, and the flock),<br /> +Urges, with turbid pressure, from above.<br /> +But when, beneath the dawn, red-fingered rays<br /> +Through the dense band of clouds diverging, break,<br /> +When springs Aurora, pale, from saffron couch,<br /> +<span class="pagenum"><a name="Page_344" id="Page_344">[Pg 344]</a></span>Ill does the leaf defend the mellowing grape;<br /> +Leaps on the noisy roof the plenteous hail,<br /> +Fearfully crackling. Nor forget to note,<br /> +When Sol departs, his mighty day-task done,<br /> +How varied hues oft wander on his brow;<br /> +Azure betokens rain: the fiery tint<br /> +Is Eurus’s herald; if the ruddy blaze<br /> +Be dimm’d with spots, then all will wildly rage<br /> +With squalls and driving showers: on that fell night,<br /> +None shall persuade me on the deep to urge<br /> +My perilous course, or quit the sheltering pier.<br /> +But if, when day returns, or when retires,<br /> +Bright is the orb, then fear no coming rain:<br /> +Clear northern airs will fan the quiv’ring grove.<br /> +Lastly, the sun will teach th’ observant eye<br /> +What vesper’s hour shall bring; what clearing wind<br /> +Shall waft the clouds slow floating—what the South<br /> +Broods in his humid breast. Who dare belie<br /> +The constant sun?”</p> + +<p>I copy also the following from Howard:</p> + +<div class="blockquot"><p>“Dr. Jenner’s signs of rain—an excuse for not accepting the +invitation of a friend to make a <i>country</i> excursion.</p></div> + +<p class="poem">“The hollow winds begin to blow,<br /> +The clouds look black, the glass is low,<br /> +The soot falls down, the spaniels sleep,<br /> +And spiders from their cobwebs creep.<br /> +Last night the sun went pale to bed,<br /> +The moon in halos hid her head,<br /> +The boding shepherd heaves a sigh,<br /> +For see! a rainbow spans the sky.<br /> +The walls are damp, the ditches smell;<br /> +Closed is the pink-eyed pimpernel.<br /> +Hark! how the chairs and tables crack;<br /> +Old Betty’s joints are on the rack.<br /> +Loud quack the ducks, the peacocks cry;<br /> +The distant hills are looking nigh.<br /> +How restless are the snorting swine!—<br /> +The busy flies disturb the kine.<br /> +Low o’er the grass the swallow wings;<br /> +The cricket, too, how loud it sings!<br /> +Puss, on the hearth, with velvet paws,<br /> +<span class="pagenum"><a name="Page_345" id="Page_345">[Pg 345]</a></span>Sits smoothing o’er her whisker’d jaws.<br /> +Through the clear stream the fishes rise<br /> +And nimbly catch the incautious flies;<br /> +The sheep were seen, at early light,<br /> +Cropping the meads with eager bite.<br /> +Though <i>June</i>, the air is cold and chill;<br /> +The mellow blackbird’s voice is still;<br /> +The glow-worms, numerous and bright,<br /> +Illumed the dewy dell last night;<br /> +At dusk the squalid toad was seen,<br /> +Hopping, crawling, o’er the green.<br /> +The frog has lost his yellow vest,<br /> +And in a dingy suit is dress’d.<br /> +The leech, disturbed, is newly risen<br /> +Quite to the summit of his prison.<br /> +The whirling wind the dust obey<br /> +And in the rapid eddy plays.<br /> +My dog, so altered in his taste,<br /> +Quits mutton-bones, on grass to feast;<br /> +And see yon rooks, how odd their flight!<br /> +They imitate the gliding kite:<br /> +Or seem precipitate to fall,<br /> +As if they felt the piercing ball.<br /> +’Twill surely rain; I see, with sorrow,<br /> +Our jaunt must be put off to-morrow.”</p> + +<p>Howard attributes the foregoing to Jenner; but Hone, in his “Every-Day +Book,” attributes it to Darwin, and gives it, with several couplets, not +found in that attributed to Jenner. These I add from Hone, as follows:</p> + +<p class="poem">“Her corns with shooting pains torment her—<br /> +And to her bed untimely send her.”</p> + +<p>That couplet is included by Hone with what is said of Aunt Betty.</p> + +<p class="poem">“The smoke from chimneys right ascends,<br /> +Then spreading back to earth it bends.<br /> +The wind unsteady veers around;<br /> +Or, settling in the south is found.”</p> + +<p><span class="pagenum"><a name="Page_346" id="Page_346">[Pg 346]</a></span>Those are as philosophically accurate and valuable as any.</p> + +<p class="poem">“The tender colts on back do lie;<br /> +Nor heed the traveler passing by.<br /> +In fiery red the sun doth rise,<br /> +Then wades through clouds to mount the skies.”</p> + +<p>The first of those couplets is untrue. It is doubtless alluded to as one +of the acts of the animal creation, indicating sleepiness and inaction, +which precede storms; but colts do not lie on the back. The other couplet +is both true and important. This collection entire, whether written by +Darwin or Jenner, contains most of the signs which have been preserved, +and which are of much practical importance in our climate.</p> + +<p>It is unquestionably true that “appointed signs foreshow the weather,” to +a great extent, every where, but with more certainty in the climate in +which Virgil wrote than in our variable and excessive one. “Showers” and +“freezing gales” we can, perhaps, as well understand; but the “<i>reign of +heat</i>,” by which he probably meant the dry period, when the southern edge +of the extra-tropical belt of rains is carried up to the north of them, we +do not experience. Something like it we did indeed have, during the +excessive northern transit, in the summer of 1854; but it was an +exception, not the rule.</p> + +<p>Some of the most important of those signs from Virgil and Jenner I propose +to allude to in detail; but it is necessary to look; in the first place, +to the character of the season and the month.</p> + +<p>We have seen that the years differ during different<span class="pagenum"><a name="Page_347" id="Page_347">[Pg 347]</a></span> periods of the same +decade. That they incline to be hot and irregular during the early part of +it, and cool, regular, and productive during the latter portion—subject, +however, to occasional exceptions. The latter half of the third decade of +this century (1826 to 1830, inclusive) was comparatively warm; and, in the +latitude of 41°, was very unhealthy, and so continued during the early +part of the next, over the hemisphere, embracing the <i>cholera seasons</i>. +The spots upon the sun were much less numerous than usual, during the +latter half of the third decade. Thus the spots from</p> + +<table border="0" cellpadding="0" cellspacing="5" summary="spots"> +<tr><td>1826 to 1830, inclusive, were <span style="margin-left: .5em;">873</span></td></tr> +<tr><td>1836 to 1840<span style="margin-left: 2em;">"</span><span style="margin-left: 2.5em;">"</span><span style="margin-left: 1em;">1201</span></td></tr> +<tr><td>1846 to 1850<span style="margin-left: 2em;">"</span><span style="margin-left: 2.5em;">"</span><span style="margin-left: 1em;">1168</span></td></tr></table> + +<p>and the size of those from 1836 to 1840 exceeded those of the other +years.</p> + +<p>The attentive observer will very soon be satisfied that the seasons have a +character; and those of every year differ in a greater or less degree from +those of other years in the same decade, and those of one decade not +unfrequently from those of some other. <i>Periodicity</i> is stamped upon all +of them, and upon all resulting consequences. Like seasons come round, +and, like productiveness or unproductiveness, healthy or epidemic +diatheses, attend them. We have seen that, in relation to mean +temperature, there are such periodical diversities, but they are more +strongly marked in the character of storms, and other successions of +phenomena. “<i>All signs fail in a drouth</i>,” for then all attempts at +condensation are partial, imperfect, and ineffectual. “<i>It rains very<span class="pagenum"><a name="Page_348" id="Page_348">[Pg 348]</a></span> +easy</i>,” it is said, at other times, and so it seems to do, and with +comparatively little condensation. In the one case, no great reliance can +be placed upon indications which are entirely reliable in the other. So +“<i>all our storms clear off cold</i>,” or, “<i>all our storms clear off warm</i>,” +are equally common expressions—as the <i>prevailing classes</i> of storms give +a <i>character</i> to the <i>seasons</i>. It “<i>rains every Sunday now</i>,” is +sometimes said, and is often peculiarly true—the storm waves having just +then a weekly or semi-weekly period, and one falls upon Sunday for several +successive weeks; and when it is so, <i>that</i> coincidence is sure to be +noticed and commented upon, and the other perhaps disregarded.</p> + +<p>If the seasons depended upon the northward and southward journey of the +sun alone, entire regularity might be expected—for we have no reason to +believe that magnetism and electricity contain, within themselves, +inherently, any tendency to irregularity, or periodicity; and, the sun +being constant in his <i>periods</i>, would be constant in his <i>influence</i>. But +he is inconstant and variable in his influence, and it is apparently +traceable to the existence of spots; but I am not quite sure that it is +occasioned by the <i>observable</i> spots alone. Grant that the intensity and +power of his rays differ on the same day, in different years, and that +difference may be attributable in part to causes which our telescopes can +not discover.</p> + +<p>But the differences in the seasons do not depend on the variability of the +sun’s influence alone. This appears from the frequent meridional and +latitudinal<span class="pagenum"><a name="Page_349" id="Page_349">[Pg 349]</a></span> diversities and contrasts, to which allusion has been made. +The sun can not be supposed to exert a <i>less</i> influence on a middle, than +a more northern latitude; nor on one series of meridians, than another. +There must, therefore, be another local and powerful disturbing cause, +varying the magnetic and electric activity and influence upon the trades, +as well in their incipiency as in their circuits, and thus controlling the +atmospheric conditions locally and in <i>the opposite hemispheres</i>. That +other disturbing cause is <i>volcanic action</i>. We can conceive of none +other, and we can detect and trace the influence of that to a considerable +extent. Unfortunately we know, and can practically know, comparatively +little of it. It has been busy with the earth since the creation, and will +continue to be so till, possibly, by a collision, it shall burst into +asteroids—its molten interior flowing out in seeming combustion—each +fragment retaining its magnetic polarities entire, and continuing on in an +independent orbit in the heavens, an asteroid, or meteorite.</p> + +<p>While, therefore, the agency of magnetism in itself may be regular, and +the transit of the sun is regular, and “seed-time and harvest shall not +cease,” yet the sun is not regular in his influence, and the magnetic +agency is disturbed by another and irregular power. And, although we can +trace the influence of both upon the seasons, we can not measure that +influence, and from it reliably foretell the weather. The discoveries of +Swabe, and future ones, relative to solar irregularities, will assist us, +but, till we understand<span class="pagenum"><a name="Page_350" id="Page_350">[Pg 350]</a></span> better, and to some extent anticipate, the +changes of volcanic action, we shall not be able to understand or foresee +all the differences in the seasons. That time may come; for progress is +yet to be read in the front of meteorology, and simultaneous practical +observations made and interchanged at every important point on the globe. +Nevertheless, the seasons have a character—often a regular one—one class +of storms prevailing over all others—one series of phenomena occurring to +the exclusion of others—and we must regard it if we would arrive at +intelligent estimates of their future condition.</p> + +<p>The most difficult part to understand are the meridional contrasts. Last +year we had one of the worst drouths which has occurred since the +settlement of the country. But while all the eastern portion of the United +States was dry, New Mexico was unusually wet; and the North-western +States, on the same curving line of the counter-trade, were not affected +by the drouth.</p> + +<p>Extract from a letter written by Governor Merriweather, to Mr. Bennett, in +answer to a circular, published in the “New York Herald,” and dated</p> + +<div class="blockquot"> +<p class="right">“<span class="smcap">Santa Fe, New Mexico</span>, Oct. 25th, 1854.</p> + +<p>“More rain has fallen during the last six months, within this +territory, than ever was known to have fallen in the same length of +time, in this usually dry climate. Generally, little or no crops have +been produced without irrigation; but this season some good crops +have been produced without any artificial watering.”</p></div> + +<p>We have seen that there was an apparent connection between the remarkable +volcanic action, exerted beneath the western continents during the second +<span class="pagenum"><a name="Page_351" id="Page_351">[Pg 351]</a></span>decade of this century, and the remarkable coldness of that decade. And +it is easy to see that the comparative absence of volcanic action from +immediately beneath the Old World, and its presence in great excess +beneath the New, may disturb the regular action of terrestrial magnetism +above it in the earth’s-crust here, and affect seasons, diatheses, and +health unfavorably; while from its absence they may be favorably affected +there. I have some general views in relation to this, but they are +necessarily speculative, for the data are few, and I reserve them.</p> + +<p>I am, however, induced to believe that the transit of the atmospheric +machinery is greater over some portions of the northern hemisphere, in +some seasons, than others. The most natural explanation of the unusual +contrast between the drouth of the Eastern States, and the wet of the +Territories, during the last summer, is, that the concentrated +counter-trade was carried west, by some irregular magnetic action in the +South Atlantic or West Indies. But there was much evidence that the +northern extension of the atmospheric machinery was greater than usual. +The transit began <i>early</i>—it was evidently <i>rapid</i>; the rains of May fell +in April, and the spring was wet; <i>summer set in earlier</i>—all the +appearances then were unusually tropical—the polar belts of condensation +descended upon us, but they were feeble, as they doubtless become, when +they reach the tropics, and did not precipitate; the summer continued full +twenty days later—no rain falling till about the 10th of September. The +season throughout was <span class="pagenum"><a name="Page_352" id="Page_352">[Pg 352]</a></span>excessive, but otherwise regular. Spring came +earlier; summer commenced earlier and continued longer; autumn held off +later, and cold weather, when it came, was uniform and severe. This season +the transit has seemed to be less than for several years.<small><a name="f10.1" id="f10.1" href="#f10">[10]</a></small> The spring +was backward; the summer cool, but exceedingly regular; the autumn thus +far without extremes, and the whole year healthy and productive. It is the +normal period of the decade, between the irregular heat of the first part, +and the irregular cold of the last; and it has been normal in character, +and conformed beautifully to its location. If the transit of 1854 was +further north than the mean, as it seemed to be over this country, that of +itself would convey the showers which follow up in the western portion of +the concentrated trade, on the east of the mountains of Mexico, and cause +them to precipitate further north, over New Mexico, and thus, rather than +from a diverted trade, they may have derived their unusual supply of +moisture during the summer of 1854. On this subject I can but conjecture, +and leave to future observation a discovery of the truth.</p> + +<p>Enough appears, however, to show the importance of taking the location of +the year in the decade, and even the character of the decade itself, into +the account.</p> + +<p>But whatever the remote cause of the difference in the seasons, the +character of the seasons is directly influenced by the character of +storms, or periodic<span class="pagenum"><a name="Page_353" id="Page_353">[Pg 353]</a></span> changes. Sometimes the tropical storms are most +numerous; at others the polar waves; and at others the irregular local +storms, or general tendency to showers. The seasons when the polar waves +are most prevalent, are the most regular, healthy, and productive. Those +where the tropical tendency is greatest, are irregular; and so are those +where the other classes predominate. These differences in the character of +the storms, are but the varying forms in which magnetic action develops +itself. I have said that there was a decided tendency to cirrus without +cumulus, in mid-winter, and cumulus without cirro-stratus or stratus, in +midsummer, and during the intermediate time an intermediate tendency. But +there is a difference between spring and autumn. Dry westerly (not N. W.) +gales prevail in March, and N. E. storms in April and May, but violent S. +E. gales are not as common. On the other hand, the dry westerly gales of +March are comparatively unknown in autumn, and the violent, tropical, +south-easters are then common.</p> + +<p>Snow-storms occur during the northern transit, not unfrequently in April +and May; but they do not occur so near the acme of the northern transit on +its return; nor until it approaches very near its southern limit. The +quiet, warm, and genial air of April, is reproduced in the Indian summer +of autumn, but they present widely different appearances. Those, and many +other peculiarities of the seasons, deserve the attentive consideration of +every one who would become familiar with the weather and its prognostics.</p> + +<p><span class="pagenum"><a name="Page_354" id="Page_354">[Pg 354]</a></span>These irregularities in the character of the seasons have doubtless always +existed, and always been the objects of popular observation. There are +some very old proverbs which show this. I copy a few of the many, which +may be found in Foster’s collection. Mr. Graham Hutchison does not seem to +think any of those ancient proverbs worthy of notice. But he misjudges. +They are the result of popular observation, and many of them accord with +the true philosophy of the weather.</p> + +<p><i>Irregular</i> seasons are unhealthy, and unreliable for productiveness. When +the southern transit was late, or limited, and the autumn ran into winter, +our ancestors feared the consequences in both particulars, and expressed +their fears, and hopes also, in proverbs. Thus,</p> + +<p class="poem">“A green winter<br /> +Makes a fat churchyard.”</p> + +<p>There is very great truth in this proverb. Again,</p> + +<p class="poem">“If the grass grows green in Janiveer,<br /> +It will grow the worse for it all the year.”</p> + +<p>This is emphatically true, for the season which commences irregularly will +be likely to continue to be irregular in other respects.</p> + +<p>Another of the same tenor:</p> + +<p class="poem">“If Janiveer Calends be summerly gay,<br /> +It will be winterly weather till Calends of May.”</p> + +<p>Janiveer is an alteration of the French name for January, and the proverb +is very old.</p> + +<p>So March should be normally dry and windy.</p> + +<p><span class="pagenum"><a name="Page_355" id="Page_355">[Pg 355]</a></span>This, too, they understood, and hence the strong proverb:</p> + +<p class="poem">“A bushel of March <i>dust</i><br /> +Is worth a king’s ransom.”</p> + +<p>And another:</p> + +<p class="poem"><span style="margin-left: 4em;">“March hack ham,</span><br /> +Come in like a lion, go out like a lamb.”</p> + +<p>So April and May should be cool and moist. It is their normal condition in +regular, healthy, and productive seasons. The grass and grain require such +conditions; and the spring rains are needed to supply the excessive summer +evaporation. This, too, they well understood. And hence the proverbs:</p> + +<p class="poem">“A cold April the barn will fill.”<br /> +<br /> +“A cool May, and a windy,<br /> +Makes a full barn and a findy.”</p> + +<p>And—</p> + +<p class="poem">“April and May are the keys of the year.”</p> + +<p>This was not very favorable, to be sure, for corn; but their consolation +was found, as we find it, in the truth of another proverb:</p> + +<p class="poem">“Look at your corn in May, and you’ll come sorrowing away;<br /> +Look again in June, and you’ll come singing in another tune.”</p> + +<p>This difference in the character of the seasons occasioned the adoption of +a great variety of “Almanac days;” and they are still very much regarded. +Candlemas-day (2d of February) was one of them.</p> + +<p>Says Hone, in his “Every-Day Book”:</p> + +<div class="blockquot"><p>“Bishop Hall, in a sermon, on Candlemas-day, remarks, that ‘it has +been (I say not how true) an old note, that hath been wont to<span class="pagenum"><a name="Page_356" id="Page_356">[Pg 356]</a></span> be set +on this day, that if it be clear and sunshiny, it portends hard +weather to come; if cloudy and lowering, a mild and gentle season +ensuing.’”</p></div> + +<p>To the same effect is one of Ray’s proverbs:</p> + +<p class="poem">“The hind had as lief see<br /> +His wife on her bier,<br /> +As that Candlemas-day<br /> +Should be pleasant and clear.”</p> + +<p>St. Paul’s day, or the 25th of January, was another great “Almanac day,” +and so the verse:</p> + +<p class="poem">“If Saint Paul’s day be fair and clear,<br /> +It does betide a happy year;<br /> +But if it chance to snow or rain,<br /> +Then will be dear all kinds of grain.<br /> +If clouds or mists do dark the sky,<br /> +Great store of birds and beasts shall die;<br /> +And if the winds do fly aloft,<br /> +Then war shall vex the kingdom oft.”</p> + +<p>St. Swithin’s day was another of these “Almanac days.” Gay said truly,</p> + +<p class="poem">“Let no such vulgar tales debase thy mind;<br /> +Nor Paul, nor Swithin, rule the clouds or wind.”</p> + +<p>Yet “<i>Almanac days</i>” are still in vogue to a considerable extent—such as +the <i>three first days</i> of the year, old style—the first three of the +season—the last of the season—different days of the month—of the +lunation, etc., etc. And some still look to the breastbone of a goose, in +the fall, to judge, by its whiteness, whether there is to be much snow +during the Winter, etc.</p> + +<p><span class="pagenum"><a name="Page_357" id="Page_357">[Pg 357]</a></span>These <i>Almanac days should all be abandoned</i>; they have no foundation in +philosophy or truth. There is one proverb, however, in relation to +Candlemas-day, which the “oldest inhabitant” will remember, and which it +may be well to retain. It has a practical application for the farmer, and +in relation to the length of the winter:</p> + +<p class="poem">“Just half of your wood and half of your hay<br /> +Should be remaining on Candlemas-day.”</p> + +<p>The months, too, have a character which must be remembered and regarded.</p> + +<p><i>January</i> is the coldest month of the year, in most localities. The +atmospheric machinery reaches its extreme southern transit, for the +season, during the month—usually about the middle. It remains stationary +a while—usually till after the 10th of February. One or more thaws, +resulting from tropical storms, occur during the month, in normal winters, +but they are of brief duration. Boreas follows close upon the retreating +storm with his icy breath. There is a remarkable uniformity in the +progress of the depression of temperature, to the extreme attained in this +month, over the entire hemisphere. It differs in degree according to +latitude and magnetic intensity; but it progresses to that degree, +whatever it may be, with as great uniformity in a southern as northern +latitude. The table, copied from Dr. Forrey, discloses the fact, and so +does the following one, taken from Mr. Blodget’s valuable paper, published +in the Patent Office Report for 1853:</p> + + +<p> <span class="pagenum"><a name="Page_358" id="Page_358">[Pg 358]</a></span></p> + +<p class="center">TABLE SHOWING THE MEAN TEMPERATURE FOR EACH MONTH AT SEVERAL PLACES, VIZ.:</p> + +<table border="0" cellpadding="0" cellspacing="0" summary="temperature"> +<tr><td class="btrl"> </td> + <td class="btr" align="center">Lat.</td> + <td class="btr" align="center">Jan.</td> + <td class="btr" align="center">Feb.</td> + <td class="btr" align="center">March.</td> + <td class="btr" align="center">April.</td> + <td class="btr" align="center">May.</td> + <td class="btr" align="center">June.</td> + <td class="btr" align="center">July.</td> + <td class="btr" align="center">Aug.</td> + <td class="btr" align="center">Sept.</td> + <td class="btr" align="center">Oct.</td> + <td class="btr" align="center">Nov.</td> + <td class="btr" align="center">Dec.</td></tr> +<tr><td class="btrl">Quebec, Canada E.</td> + <td class="btr" align="center">46° 49′</td> + <td class="btr" align="center"><span style="margin-left: .5em;">9.9</span></td> + <td class="btr" align="center">12.8</td> + <td class="btr" align="center">24.4</td> + <td class="btr" align="center">38.7</td> + <td class="btr" align="center">52.9</td> + <td class="btr" align="center">63.7</td> + <td class="btr" align="center">66.8</td> + <td class="btr" align="center">65.5</td> + <td class="btr" align="center">56.2</td> + <td class="btr" align="center">44.1</td> + <td class="btr" align="center">31.5</td> + <td class="btr" align="center">17.3</td></tr> +<tr><td class="blr">New York, N. Y.</td> + <td class="br" align="center">40° 42′</td> + <td class="br" align="center">30.2</td> + <td class="br" align="center">30.8</td> + <td class="br" align="center">38.5</td> + <td class="br" align="center">49.1</td> + <td class="br" align="center">59.6</td> + <td class="br" align="center">69.1</td> + <td class="br" align="center">74.9</td> + <td class="br" align="center">73.3</td> + <td class="br" align="center">65.9</td> + <td class="br" align="center">54.3</td> + <td class="br" align="center">43.5</td> + <td class="br" align="center">33.9</td></tr> +<tr><td class="blr">Albany, N. Y.</td> + <td class="br" align="center">42° 39′</td> + <td class="br" align="center">24.5</td> + <td class="br" align="center">24.3</td> + <td class="br" align="center">34.8</td> + <td class="br" align="center">47.7</td> + <td class="br" align="center">59.8</td> + <td class="br" align="center">68.0</td> + <td class="br" align="center">72.2</td> + <td class="br" align="center">70.3</td> + <td class="br" align="center">61.4</td> + <td class="br" align="center">49.2</td> + <td class="br" align="center">39.4</td> + <td class="br" align="center">28.3</td></tr> +<tr><td class="blr">Rochester, N. Y.</td> + <td class="br" align="center">42° 45′</td> + <td class="br" align="center">26.1</td> + <td class="br" align="center">25.8</td> + <td class="br" align="center">33.0</td> + <td class="br" align="center">45.8</td> + <td class="br" align="center">56.2</td> + <td class="br" align="center">64.5</td> + <td class="br" align="center">69.7</td> + <td class="br" align="center">67.8</td> + <td class="br" align="center">60.1</td> + <td class="br" align="center">47.7</td> + <td class="br" align="center">38.2</td> + <td class="br" align="center">28.8</td></tr> +<tr><td class="blr">Baltimore, Md.</td> + <td class="br" align="center">39° 17′</td> + <td class="br" align="center">33.1</td> + <td class="br" align="center">34.3</td> + <td class="br" align="center">42.4</td> + <td class="br" align="center">53.0</td> + <td class="br" align="center">63.2</td> + <td class="br" align="center">71.6</td> + <td class="br" align="center">76.6</td> + <td class="br" align="center">74.5</td> + <td class="br" align="center">67.7</td> + <td class="br" align="center">55.8</td> + <td class="br" align="center">45.0</td> + <td class="br" align="center">37.8</td></tr> +<tr><td class="blr">Savannah, Ga.</td> + <td class="br" align="center">32° 05′</td> + <td class="br" align="center">52.6</td> + <td class="br" align="center">54.7</td> + <td class="br" align="center">60.0</td> + <td class="br" align="center">68.4</td> + <td class="br" align="center">74.8</td> + <td class="br" align="center">79.4</td> + <td class="br" align="center">81.3</td> + <td class="br" align="center">80.6</td> + <td class="br" align="center">76.9</td> + <td class="br" align="center">67.2</td> + <td class="br" align="center">58.3</td> + <td class="br" align="center">52.2</td></tr> +<tr><td class="blr">Key West, Fla.</td> + <td class="br" align="center">24° 33′</td> + <td class="br" align="center">70.0</td> + <td class="br" align="center">70.7</td> + <td class="br" align="center">73.8</td> + <td class="br" align="center">76.3</td> + <td class="br" align="center">80.2</td> + <td class="br" align="center">82.1</td> + <td class="br" align="center">83.3</td> + <td class="br" align="center">83.5</td> + <td class="br" align="center">82.5</td> + <td class="br" align="center">79.1</td> + <td class="br" align="center">75.6</td> + <td class="br" align="center">72.8</td></tr> +<tr><td class="blr">Mobile, Ala.</td> + <td class="br" align="center">30° 40′</td> + <td class="br" align="center">51.3</td> + <td class="br" align="center">53.7</td> + <td class="br" align="center">59.4</td> + <td class="br" align="center">67.1</td> + <td class="br" align="center">74.1</td> + <td class="br" align="center">77.8</td> + <td class="br" align="center">79.8</td> + <td class="br" align="center">79.4</td> + <td class="br" align="center">76.1</td> + <td class="br" align="center">65.7</td> + <td class="br" align="center">57.0</td> + <td class="br" align="center">52.8</td></tr> +<tr><td class="blr">New Orleans, La.</td> + <td class="br" align="center">30° 00′</td> + <td class="br" align="center">54.8</td> + <td class="br" align="center">54.5</td> + <td class="br" align="center">61.5</td> + <td class="br" align="center">67.6</td> + <td class="br" align="center">74.0</td> + <td class="br" align="center">78.6</td> + <td class="br" align="center">80.4</td> + <td class="br" align="center">79.6</td> + <td class="br" align="center">77.1</td> + <td class="br" align="center">69.1</td> + <td class="br" align="center">57.5</td> + <td class="br" align="center">56.2</td></tr> +<tr><td class="blr">Marietta, Ohio</td> + <td class="br" align="center">39° 25′</td> + <td class="br" align="center">32.2</td> + <td class="br" align="center">34.1</td> + <td class="br" align="center">42.6</td> + <td class="br" align="center">53.0</td> + <td class="br" align="center">61.8</td> + <td class="br" align="center">69.2</td> + <td class="br" align="center">72.7</td> + <td class="br" align="center">70.9</td> + <td class="br" align="center">63.5</td> + <td class="br" align="center">51.8</td> + <td class="br" align="center">42.6</td> + <td class="br" align="center">34.7</td></tr> +<tr><td class="blr">San Antonio, Tex.</td> + <td class="br" align="center">29° 25′</td> + <td class="br" align="center">52.7</td> + <td class="br" align="center">57.9</td> + <td class="br" align="center">65.5</td> + <td class="br" align="center">69.7</td> + <td class="br" align="center">76.4</td> + <td class="br" align="center">80.5</td> + <td class="br" align="center">82.3</td> + <td class="br" align="center">83.3</td> + <td class="br" align="center">79.9</td> + <td class="br" align="center">72.2</td> + <td class="br" align="center">62.2</td> + <td class="br" align="center">52.1</td></tr> +<tr><td class="bblr">San Francisco, Cal.</td> + <td class="bbr">37° 48′</td> + <td class="bbr">50.1</td> + <td class="bbr">51.0</td> + <td class="bbr"><span style="margin-left: .5em;">53.8</span></td> + <td class="bbr">57.7</td> + <td class="bbr">55.9</td> + <td class="bbr">58.8</td> + <td class="bbr">57.9</td> + <td class="bbr">62.2</td> + <td class="bbr">61.6</td> + <td class="bbr">61.9</td> + <td class="bbr">56.2</td> + <td class="bbr">50.0</td></tr></table> + +<p><span class="pagenum"><a name="Page_359" id="Page_359">[Pg 359]</a></span>Snows during this month are much heavier, and more frequent, in some +localities than others. The reasons why this is so have been stated. The +mountainous portions of the country receive the heaviest falls. They +affect condensation somewhat, and according to their elevation. They +intercept the flakes before they melt, and retain them longer without +change. The thaws, or tropical storms, also sometimes have a current of +cold air, with snow setting under them on their northern and north-western +border. Such was the case with that investigated by Professor Loomis. +January is without other marked peculiarities. It shows, of course, those +extremes of temperature found, to a greater or less degree, in all the +months, and differs, as the others differ, in different seasons. Normally, +in temperate latitudes, it is a healthy month. The digestive organs have +recovered from that tendency to bilious diseases which characterizes the +summer extreme northern transit, and the tendency to diseases of the +respiratory organs, which characterizes the southern extreme and the +commencement of its return, is not often developed till February. +February, in its normal condition until after the 10th, and about the +middle, is much like January. Often the first ten days of February are the +coldest of the season. The average of the month is a trifle higher, in +most localities, as the tables show. This results from the increasing +warmth of the latter part of the month. There are localities, however, +where the entire month is as cold as January. Such (as will appear from +Blodget’s<span class="pagenum"><a name="Page_360" id="Page_360">[Pg 360]</a></span> table) are Albany and Rochester, in the State of New York, and +New Orleans, in Louisiana. At most places the difference is slight, either +way. South of the latitude of 40° heavy snows are more likely to occur in +the last half of January and first half of February than earlier. About +the middle of the month we may expect thaws of more permanence in normal +seasons. They are followed, as in January, by N. W. wind and cold weather, +but it is not usually as severe. Many years since, an observing old man +said to me, “<i>Winter’s back breaks about the middle of February</i>.” And I +have observed that there is usually a yielding of the extreme weather +about that period. Here, again, it is interesting and instructive to look +at the tables, and see how regularly and uniformly the temperature rises +in all latitudes, at the same time; as early and as rapidly at Quebec as +at New Orleans or San Antonio; and subsequently rises with greatest +rapidity where the descent was greatest. The elevation of temperature does +not progress northwardly, a wave of heat accompanying the sun, but is a +magneto-electric change, commencing about the same time over <ins class="correction" title="original: the the">the</ins> whole +country, and indeed over the hemisphere.</p> + +<p>March is a peculiar month—the month of what is termed, and aptly termed, +“unsettled weather.” It, may “come in like a lion,” or be variable at the +outset. The northern transit is fairly started, and is progressing +rapidly, and there is great magnetic irritability. A reference to the +table of Dr. Lamont will show that the declination has increased with<span class="pagenum"><a name="Page_361" id="Page_361">[Pg 361]</a></span> +great rapidity. Normally, the early part is like the latter part of +February, and the latter part approaches the milder but still changeable +weather of April. Its distinguishing feature is violent westerly wind. Not +the regular N. W. only—although that is prevalent—but a peculiar +westerly wind, ranging from W. by N. to N. W. by W., often blowing with +hurricane violence. This wind was alluded to on page 130. With the change +and active transit to the north, in February and in March, comes the +tendency to diseases of the respiratory organs—pneumonias and lung +fevers—and this is the most dangerous period of the year for aged people.</p> + +<p>April is a milder and more agreeable month. During some period of it, in +normal seasons, and at other times in March, there is a warm, quiet, +genial, “lamb-”like <i>spell</i>, exceedingly favorable for oat seeding. When +it comes, advantage should be taken of it, for long heavy N. E. storms are +liable to occur, and frequently with snow. On the latitude of 41° heavy +snow-storms are not uncommon in April. Within the last fifteen years two +such have occurred after the 10th of the month. April, as we have seen, +should be cool and moist. If dry, the early crops are endangered by a +spring drouth; if very wet, there is danger of an extreme northern +transit, and an early summer drouth. It is emphatically true that</p> + +<p class="poem">“April and May are the keys of the year.”</p> + +<p>Its distinguishing peculiar feature is the gentle,<span class="pagenum"><a name="Page_362" id="Page_362">[Pg 362]</a></span> <i>warm</i>, <i>trade</i> +rains—“<i>April showers</i>”—which, in the absence of great magnetic +irritability, that current drops upon us. There is great <i>mean</i> magnetic +activity, but it is not so <i>irregularly excessive</i> as in March.</p> + +<p>May, in our climate, should be, and normally is, a wet month, and a cool +one, considering the altitude of the sun. The atmospheric machinery which +the sun moves is, however, ordinarily about six weeks behind it—the +latter reaching the tropic the 20th of June, and the former its farthest +northern extension about six weeks later. Hence it is not a cause for +alarm if May be wet and cool. The great staples, wheat, grass, and oats, +are benefited; and corn, according to the proverb, will not be seriously +retarded. The movable belt of excessive magneto-electric action, with its +tropical electric rains, so exciting to vegetation, and its periods or +terms of excessive heat, is on its way north, and sure to arrive in +season, and remain long enough to mature the corn. There have been but two +seasons in this century when corn did not mature in the latitude of 41°. +One during the cold decade, and the cold part of it, between 1815 and +1820; and the other, during the cold half of the fourth decade, between +1835 and 1840.</p> + +<p>The distinguishing feature, if there be one, of May, is its long, and, for +the season, cool storms. These have, in different localities, different +names. In pastoral sections we hear of the “<i>sheep storms</i>”—those which +effect the sheep severely when newly shorn—killing them or reducing them +in flesh by their coldness and severity.</p> + +<p><span class="pagenum"><a name="Page_363" id="Page_363">[Pg 363]</a></span>In relation to this too early shearing, there is an old English proverb, +in “Forster’s Collection,” viz.:</p> + +<p class="poem">“Shear your sheep in May,<br /> +And you will shear them all away.”</p> + +<p>So there are others called “<i>Quaker storms</i>,” which occur about the time +when that estimable sect hold their yearly meeting. And there are other +names given in different localities to these long spring storms. But they +are all <i>mere coincidences</i>—equinoctial and all.</p> + +<p>Notwithstanding the storms, however, the temperature rises at a mean. The +declination is often as great as in mid-summer. The earth is growing +warmer by the increase of magneto-electric action, whatever the state of +the atmosphere. The yellow, sickly blade of corn is extending its roots +and preparing to “<i>jump</i>” when the atmosphere becomes hot, as it is sure +to do, when the machinery attains a sufficient altitude, how backward +soever it may seem to be. The farmer need not mourn over its backwardness, +unless the season is a very extraordinary one, like those of 1816 and +1836. The storms ensure his hay, wheat, and oat crops; the warming earth +is at work with the roots of his corn, and is filling with water, and +preparing for the hot and rapidly-evaporating suns of mid-summer. The +earth would grow warmer if every day was cloudy.</p> + +<p>By the middle of June the atmospheric machinery approaches its northern +acme, the summer sets in, and not unfrequently, as extremely hot days +occur<span class="pagenum"><a name="Page_364" id="Page_364">[Pg 364]</a></span> during the latter part of the month, as at any period of the +summer. But the heat is not so continuous, or great, at a mean.</p> + +<p>From the middle of June to the latter part of August is summer in our +climate, and during that period from one to three or four terms of extreme +heat occur, continuing from one to five or six days, and possibly more, +terminating finally in a belt of showers overlaid with more or less +cirro-stratus condensation in the trade, and controlled by the S. E. polar +wave of magnetism, and followed by a cool but gentle northerly wind. +During these “heated terms,” a general showery disposition sometimes, +though rarely, appears, with isolated showers, which bring no mitigation +of the heat. Not until a southern extension of them appears, followed by a +N. W. air, does the term change, so far as I have observed.</p> + +<p>By the 20th of August, in the latitude of 42°, an evident change of +transit is observable, by one who watches closely, although the range of +the thermometer in the day-time may not disclose it. A greater tendency to +cirrus-formation is visible. The nights grow cooler in proportion to the +days. The swallows are departing, or have departed; the blackbirds, too, +and the boblinks, with their winter jackets on, <i>their plumage all changed +to the same colors</i>, are flocking for the same purpose, and hurrying away. +The pigeons begin to appear in flocks from the north, and the first of the +blue-winged teal and black duck are seen straggling down the rivers. At +this season,<span class="pagenum"><a name="Page_365" id="Page_365">[Pg 365]</a></span> and nearly coincident with the change, the peculiar annual +catarrhs return. These are colds (so called) which at some period of the +person’s life were taken about or soon after the period of change, and +have returned every year, at, or near the same period. They soon become +<i>habitual</i>, and no care or precaution will prevent them. I know one +gentleman who has had this annual cold in August for twenty-seven years, +with entire regularity; and another who has had it nineteen years; and +many others for shorter periods. I never knew one which had recurred for +two or three years that could be afterward prevented, or broken up. <i>Very +instructive are these annual catarrhs</i> to those who think health worth +preserving, and in relation to the change of transit.</p> + +<p><i>The change is felt over the entire hemisphere.</i> Between the 20th of +August and the 10th of September hurricanes originate in the tropics and +pursue their curving and recurving way up over us; or long “north-easters” +commence in the interior and pass off to E. N. E. on to the Atlantic, +followed now in a more marked degree by the peculiar N. W. wind, so common +over the entire Continent in autumn and winter.</p> + +<p>By the 10th of September the pigeons may be seen in flocks in the morning, +and just prior to the setting in of a brisk N. W. wind, hurrying away +southward with a sagacity that we scarcely appreciate, to avoid the +anticipated rigors of winter, and to be followed soon by all the migratory +feathered tribes that remain.</p> + +<p><span class="pagenum"><a name="Page_366" id="Page_366">[Pg 366]</a></span>The nights grow cooler, although the sun shines hot in the day-time, and +woe to the person, unless with an iron constitution, who disregards the +change, and exposes himself or herself without additional protection, to +its influence. Nature has taken care of those who depend upon her, or upon +instinct, for protection. The feathers of birds and water-fowl are full; +the hair and the fur are grown. Beasts and birds have been preparing for +the change, and are ready when it begins. They know that the earth is +changing. The shifting machinery is fast carrying south that excess of +negative electricity which has so much to do with giving it its summer +heat. They feel its absence, even during the day, and the contrast between +that and the positively electrified northern atmosphere, which now follows +every retreating wave of condensation.</p> + +<p>The musk-rat builds, of long grass and weeds, his floating nest in the +pond, that he may have a place to retire to, when the rain fills it up and +drives him from his burrow in its banks.</p> + +<p>But man, with all his intellect, is too heedless of the change. Additional +clothing is now as necessary to him as to animals, but it is burdensome to +him in the day time, and therefore he will not wear it, how much soever it +would add to his comfort and safety during the night. He stands with his +thin summer soles upon the changed ground, or sits in a current, or in the +night air, less protected than the animals, and dysentery or fever sends +him to his long home. He has <i>intelligence</i>, but he lacks <i>instinct</i>. He +has time for<span class="pagenum"><a name="Page_367" id="Page_367">[Pg 367]</a></span> the changes of dress which fashion may require, but none for +those which atmospherical changes demand. <i>Fashion</i> has attention in +<i>advance</i>; <i>death</i> none till <i>at the door</i>.</p> + +<p>Now the southern line of the extra-tropical belt of rains descends upon +those who, living between the areas of magnetic intensity, have a dry +season; and the focus of precipitation in that belt descends every where. +“<i>Winter no come till swamps full</i>,” the Indians told our fathers, and +there is truth in the remark; although like other general truths +respecting the weather, it is not always so in our climate. Rains fall +during the autumnal months, as during the spring months, and while the +transit of the machinery is active and the evaporation is less. And the +magnetic comparative rest, and the seed time and equable “spell” of April +is reproduced in the Indian summer of autumn.</p> + +<p>The machinery gradually and irresistibly descends, and with an excess of +polar positive electricity, comes snow; Boreas controls, and winter sets +in, reaching its maximum of cold in January again.</p> + +<p>Remembering, then, the differences in the normal conditions of the seasons +and months, and the different characters that the winds, and storms, and +clouds, and other phenomena bear in them respectively, let us now look at +the signs of foul or fair weather not herein before fully stated, upon +which practical reliance may be placed.</p> + +<p>In the first place, we must look to the forming condensation. There are +many days when the <span class="pagenum"><a name="Page_368" id="Page_368">[Pg 368]</a></span>atmosphere is without visible clouds, but few when it +is entirely without condensation. Such days are seen during the dry season +in the trade-wind region; and with us, in mid-summer drouths, which +partake of this tropical character; and when, at any season, but +particularly in winter, the N. W. wind in large volume has elevated the +trade very high. Condensation is not necessarily in form of visible cloud. +It may be of that smoky character which sometimes attends mid-summer +drouths, giving the sun a blood-red appearance; or it may be like that +change from deep azure to a “lighter hue,” obscuring the vision, which +Humboldt describes as preceding the arrival of the inter-tropical belt of +rains. Gay-Lussac, and other aeronauts, have seen a thin cloud stratum at +the height of 20,000 to 30,000 feet, not visible at the earth, although +some degree of mistiness and obscurity were observed. At that elevation +the clouds are thin, and always white and positive. Some degree of +turbidness is frequent; it may occur, as we have stated, with N. W. wind, +but, if it does, the wind soon changes round to the southward.</p> + +<p>This turbidness or mistiness, where it exists, and indicates rain, does +not disappear toward night, as it should do if but the daily cloudiness +which results from ordinary diurnal magnetic activity, but becomes more +obvious at nightfall; and, when hardly visible at mid-day, or during the +afternoon, may then be observed, obscuring in a degree, the sun’s rays; +and, later in the evening, forming a circle round the moon. Thus Jenner—</p> + +<p class="poem"><span class="pagenum"><a name="Page_369" id="Page_369">[Pg 369]</a></span> +“Last night the sun went <i>pale to</i> bed,<br /> +The moon in <i>halos</i> hid her head.”</p> + +<p>And so, too, Virgil—</p> + +<p class="poem">“The sun, too, rising, and at that still hour,<br /> +When sinks his tranquil beauty in the main,<br /> +Will give thee tokens; certain tokens all,<br /> +Both those that morning brings, and balmy eve.<br /> +<span class="spacer">*</span><span class="spacer">*</span><span class="spacer">*</span><span class="spacer">*</span><span class="spacer">*</span><span class="spacer">*</span><span class="spacer">*</span><br /> +When Sol departs, his mighty day-task done,<br /> +How varied hues oft wander on his brow.<br /> +<span class="spacer">*</span><span class="spacer">*</span><span class="spacer">*</span><span class="spacer">*</span><span class="spacer">*</span><span class="spacer">*</span><span class="spacer">*</span><br /> +<span style="margin-left: 8em;">If the ruddy blaze</span><br /> +Be <i>dimm’d</i> with <i>spots</i>, then all will wildly rage<br /> +With squalls and driving showers: on that fell night<br /> +None shall persuade me on the deep to urge<br /> +My perilous course, or quit the sheltering pier.<br /> +But if, when day returns, or when retires,<br /> +<i>Bright</i> is the orb, then fear no coming rain:<br /> +Clear northern airs will fan the quiv’ring grove.<br /> +Lastly, the sun will teach th’ observant eye<br /> +What vesper’s hour shall bring; what clearing wind<br /> +Shall waft the clouds slow floating—what the South<br /> +Broods in his humid breast. Who dare belie<br /> +The constant sun?”</p> + +<p>More frequently this kind of condensation is sufficiently dense at +night-fall to take shape, and show a bank when the sun shines horizontally +through a mass of it. I am now speaking of <i>storm</i> condensation, or that +which indicates the approach of a storm. Thunder clouds at nightfall, +dark, dense, and isolated, are, of course, to be distinguished. Those, +every one understands to indicate a shower, and immediate succeeding fair +weather.</p> + +<p>The halos do not, in cases of incipient storm condensation, always appear. +The moon may not be present: though, in her absence, I have seen them in<span class="pagenum"><a name="Page_370" id="Page_370">[Pg 370]</a></span> +the light of the primary planets; or she may be in the eastern portion of +the heavens. When this is so, and the condensation forms slowly, there may +be less appearance of it, after the sun disappears, than before, although +a storm is approaching, and sure to be on by the middle of next day, and +perhaps with great violence. When the failure of the light no longer +reveals the denser condensation in the west, the stars may shine, as did +the sun, dimly but visibly, through the partial and invisible +condensation; and one who did not notice the bank in the west, at +nightfall and before dark, may be deceived by the seeming clearness of the +evening. Thus Virgil—</p> + +<p class="poem">“Mark, with attentive eye, the rapid sun—<br /> +The varying moon that rolls its monthly round;<br /> +So shalt thou count, not vainly, on the morn;<br /> +<i>So the bland aspect of the tranquil night<br /> +Will ne’er beguile thee with insidious calm</i>.”</p> + +<p>All early condensation and indications derived from it, must be looked for +in the west. From that quarter all storms come. These indications at +nightfall are of a varied character. They may consist of primary +condensation in the trade, or of secondary condensation, scud running +north toward a storm, the condensation of which has not yet visibly +reached us, but which will extend south and pass over us. It may be a +heavy bank, or consist of narrow cirrus bands. Cirro-stratus cloud banks, +in the S. W., in the fall and winter, of a foggy and uniform character, +are indicative of snow. The body of the storm will pass south of us, and a +portion over us, the wind<span class="pagenum"><a name="Page_371" id="Page_371">[Pg 371]</a></span> be north of east, and the snow will not be +likely to turn to rain before it reaches the earth, by reason of a +southern middle current.</p> + +<p>Banks in the N. W. indicate rain at all seasons. The storm is north of us, +working southerly, and such storms rain on the southern border—in winter +even—because they have the wind on that border from south of east. It +may, indeed, snow, but if so, probably in large flakes, soon turning to +rain. There are other appearances at nightfall which deserve +consideration. A red sun, with smoky air, is indicative of continued dry +weather, a frequent appearance in dry terms, lasting three or four days, +at least, from the commencement. So is a red appearance of the sky, when +there are no clouds, indicative of a fair day following. On this subject +we have an allusion to the weather, by our Saviour while on earth, which, +like all such allusions found in the Bible, is of remarkable philosophical +accuracy. It is found in Matthew, chapter xvi., verses 2 and 3: “He +answered and said unto them, When it is evening ye say, It will be fair +weather, for the sky is red. And in the morning, It will be foul weather +to-day, for the sky is red and lowering. O, ye hypocrites, ye <i>can +discern</i> the face of the sky,” etc.</p> + +<p>Another allusion to the weather, though not applicable to this point, I +will refer to in passing. It is found in Luke, chapter xii., verses 54 and +55: “And he said also to the people, When ye see a cloud rise out of the +west straightway ye say, There cometh a shower; and so it is. And when ye +see the south<span class="pagenum"><a name="Page_372" id="Page_372">[Pg 372]</a></span> wind blow, ye say, There will be heat; and it cometh to +pass.”</p> + +<p>This is all very true, and might have been cited to show the universality +of the phenomena. But to return.</p> + +<p>We have an old English proverb alluding to the same phenomena, of great +value and truth, viz.:</p> + +<p class="poem">“An evening red and a morning gray<br /> +Are sure signs of a fair day;<br /> +Be the evening gray and the morning red,<br /> +Put on your hat or you’ll wet your head.”</p> + +<p>The sky is red if there be no condensation at the west to obscure the rays +of the sun; if there be, it is gray, or there is a bank or cloud, and it +is obscured. So if there be no condensation over, or to the east of us, in +the morning, to reflect the rays of the sun, the sky is gray; if there be +such condensation, the sun is reflected from it, and the sky is red. Such +morning condensation is indicative of foul weather. It is, as we have +said, the eastern edge of an approaching storm, on, or under which, the +sun shines and illumines it. Thus, at night, it shines through a portion +at the west, which is situate between the sun and us, making the sky gray: +but shines on, or under, a portion in the morning, east of us, but not far +enough east to obscure the horizon, and the rays of the rising sun are +reflected from it. In either case the red or gray appearance results from +the relative situation of the sun and the eastern edge of an approaching +storm.</p> + +<p><span class="pagenum"><a name="Page_373" id="Page_373">[Pg 373]</a></span>The following couplet of Darwin is an apt description of the morning +appearance:</p> + +<p class="poem">“In fiery red the sun doth rise,<br /> +Then wades through clouds to mount the skies.”</p> + +<p>The sun is often reflected in vivid colors, from the under surface of +clouds, at sunset. This is an indication of fair weather. It is evident +the sun shines through a <i>clear atmosphere beyond the cloud</i>, or his rays +would not reach and illume the lower surface of the cirro-stratus with +such distinctness. He “<i>sets clear</i>,” as is said; the clouds are passing +off, and there are none beyond. It is this appearance, in different forms, +when there happen to be patches of broken, melting cirro-stratus above the +horizon, which makes the beautiful sunsets that attract attention. So the +sun is reflected, in beautiful colors sometimes, from the cumulus clouds +which have passed over to the east. The most beautiful and variegated I +have ever seen, were reflected from that imperfect cumulus condensation +which takes place occasionally during long drouths—doubtless resembling +that which is seen over Peru, hereinbefore alluded to, as described by +Stewart.</p> + +<p>It is not, then, the presence of cloud condensation at the west, at +nightfall, which alone indicates foul weather; but such condensation, +whatever its form, as evinces that it is not the <i>dissolving</i> cloud of the +day, but the eastern, approaching portion of a <i>still denser portion +beyond, through, or under which, the sun can not shine clearly, but which +wholly or partially obscures it</i>.<span class="pagenum"><a name="Page_374" id="Page_374">[Pg 374]</a></span> <i>Remembering this philosophy of the +matter</i>, the observer will soon be able to detect the various forms of +condensation which originate or exhibit themselves at nightfall, and +whether they indicate an approaching storm or not, without a more explicit +specification of them. It is an important hour for observation; “Let not +the sun go down” without attention.</p> + +<p>When the condensation is obvious, but thin, at nightfall, it may not, as I +have said, be discernible in the evening. But there are methods by which +the incipient storm condensation may be detected. The number of the stars +visible, and the <i>distinctness</i> with which they may be seen, indicate the +absence or presence of condensation and its density. Virgil, alluding to +the indications of fair weather, says:</p> + +<p class="poem">“<i>Brightly</i> the stars shine forth; Cynthia no more<br /> +<i>Glimmers</i> obnoxious to her brother’s rays;<br /> +Nor fleecy clouds float lightly through the sky.”</p> + +<p>The brightness of the stars and the clear appearance of the moon show the +absence of condensation and the <i>dissolution</i> of the fleecy clouds at the +close of the day is, as we have seen, always a fair-weather indication.</p> + +<p>There is much true philosophy in the allusions of Virgil to the moon. +Thus—</p> + +<p class="poem">“When Luna first her scatter’d fires recalls,<br /> +If with <i>blunt horns</i> she holds the <i>dusky</i> air,<br /> +Seamen and swains predict th’ abundant shower.”</p> + +<p>The horns, or angles of the moon will, of course, appear distinct and +sharp or indistinct and blunt, in<span class="pagenum"><a name="Page_375" id="Page_375">[Pg 375]</a></span> proportion to the amount of +condensation in the atmosphere which impedes the passage of the light. For +the same reason, when the moon is new, her entire disk is visible when the +atmosphere is very clear, by reason, as is supposed, of light reflected +from the earth to the moon and back to us. This double reflection can only +take place when the atmosphere is very clear. Hence, Virgil alludes to it, +and correctly, as an indication of continued fair weather:</p> + +<p class="poem"><span style="margin-left: 6em;">“If (mark the ominous hour!)</span><br /> +The clear fourth night her lucid disk define,<br /> +That day, and all that thence successive spring,<br /> +E’en to the finished month, are calm and dry.”</p> + +<p>Probably Virgil alluded to a month of the summer trade-wind drouth which +reaches up on Southern Italy. But that appearance of the moon is +occasionally seen here, and the indication is, in degree, philosophically true.</p> + +<p>It is somewhat more difficult to determine what will be the result of the +condensation seen at the west in the morning, and which is not so far +east, or of such a character, as to reflect the rays of the sun; for, +although always suspicious, it is sometimes of a foggy character, and +disappears between eight and nine o’clock. If it increases in density +after ten o’clock, or is of a dense cirro-stratus character, rain may +generally be expected. If of a decided <i>cirro-cumulus</i> character, it is +certain to disappear. Cirro-cumulus is seen in small patches, with small, +distinct, and rounded masses, in summer, in the morning, and<span class="pagenum"><a name="Page_376" id="Page_376">[Pg 376]</a></span> sometime, +during the day, after high fog has disappeared, and at other times, and is +always, when of that <i>distinct</i> character, a fair weather indication. I +have seen it thus when the wind was blowing from the N. E., and the scud +running toward a storm passing near, but to the south of us, when those +who relied upon the existence of the wind and scud as evidences that we +were to have the desired rain, were deceived. Thus, the couplet from an +old almanac:</p> + +<p class="poem">“If <i>woolly fleeces</i> strew the heavenly way,<br /> +Be sure no rain disturb the summer day.”</p> + +<p>When this morning condensation is not high fog, and is dense and passing +east with a wavy appearance, it is very certain to rain. Jenner says:</p> + +<p class="poem">“The boding shepherd heaves a sigh,<br /> +<i>For see, a rainbow spans the sky</i>.”</p> + +<p>An old almanac had the following verse:</p> + +<p class="poem">“A rainbow in the morning<br /> +Is the shepherd’s warning;<br /> +A rainbow at night<br /> +Is the shepherd’s delight.”</p> + +<p>So the proverb was originally made; but as our ancestors were not +shepherds, and had a horror of ocean storms, it was commonly quoted, in +this country, in the following form:</p> + +<p class="poem">“A rainbow in the morning,<br /> +The sailors take warning,” etc.</p> + +<p><span class="pagenum"><a name="Page_377" id="Page_377">[Pg 377]</a></span>Rainbows are not reflected from <i>clouds</i>, but falling rain, and a morning +rainbow at the west is, of course, evidence that it is <i>actually raining +there</i>, and will, in all probability, pass over us. “Thunder in the +morning, rain before night,” is a common saying, and a true one. There is +a belt of showers, or showery period approaching, of unusual +intensity—for thunder showers in the morning are rare. The afternoon is +their most common period, and they are very apt to appear then, when the +morning is showery.</p> + +<p>Of the different forms of cirrus and cirro-stratus, which appear during +the day, and indicate approaching storms, or of cumulus indicative of +showers, it is difficult to give an intelligible description without very +many illustrations. I have many daguerreotype views, taken at different +seasons of the year, and at a time when different forms of cirrus and +cirro-stratus condensation, indicative of storms, exhibited themselves. +They differ, as I have said, and it must be remembered, very much at +<i>different seasons</i> of the year, and in <i>different years</i>, and their +delicate shades are taken with difficulty by the artist, and reproduced +with difficulty, and only at considerable expense, by the engraver; and I +have omitted them. The time will come when a knowledge of their language +will be sought for and read—when the “countenance of the sky” will be an +object of intelligent interest to all whose business may be affected by +the weather, or who love to learn of nature. But it is not yet. This is +the age of theory and speculation. The time of actual, practical, +connected observation<span class="pagenum"><a name="Page_378" id="Page_378">[Pg 378]</a></span> and prognostication, which may justify expensive +illustration, is yet to arrive.</p> + +<p>The reader will find in the general plates representations of several +kinds of cirri. They are delicate, always white, more or less fibrous, and +form in the upper part of the trade or the adjoining atmosphere above it. +Their character and elevation should be studied, and the observer should +be careful to distinguish which is the most elevated. Not unfrequently it +may seem, to a hasty observer, that the cirrus is below the cirro-stratus +or forming stratus. But the genuine cirrus never is. It forms near, and +above, the point of congelation, and is often composed of crystals of ice +or snow. If they fall, they melt and evaporate, when there is no storm, +before reaching the earth. Aeronauts have met with them and their crystals +when there was no fall of moisture at the surface of the earth; and the +angles of reflection exhibited by halos and other optical phenomena which +form in them, enable us to detect their crystallization and the form of +it.</p> + +<p>They are produced by electric changes which condense the vapor, and the +coldness of the air at that elevation freezes it at the <i>instant of its +condensation</i>.</p> + +<p>Congelation is crystallization, and all crystallization is electric, or +magneto-electric. The snow-flakes differ in form and size according to the +suddenness of the condensation, the amount of moisture condensed, the +polarity of the strata through which they pass, and their consequent +attraction and adhesion to each other.</p> + +<p><span class="pagenum"><a name="Page_379" id="Page_379">[Pg 379]</a></span>The connection of electricity with these formations of cirri has +frequently been admitted, and it is perfectly obvious that the long +fibrous bands, shooting from horizon to horizon, could not be formed by +commingling of currents any more than the perfectly isolated, distinct, +enlarging-outward cumulus hail-storm, could be so formed. Cirri form at +the line of meeting, between the trade and the upper atmosphere, and in +one or the other, or both, very much according to the season, and the +suddenness with which storms are produced. These often <i>induce</i> a layer of +cirro-stratus or stratus at the lower line of the counter-trade, and in +the surface-atmosphere, which precipitates; and this operation is clearly +discernible, and very frequently, before gentle rains. Condensation in the +whole body of the trade is usually in the form of turbidness or mistiness, +a bank or incipient stratus, without cirri.</p> + +<p>It seems matter of astonishment that water should float so far condensed, +in strata where the air is so much lighter, without being precipitated. +But electric attraction and repulsion between the different strata and the +vesicles, explain it.</p> + +<p>In mid-winter, the cirrus forms are prevalent and most distinct. After +severe cold weather, when a storm approaches, the cirri form in long, +narrow threads, parallel to each other, extending from about W. S. W. to +E. N. E., gradually thickening and forming, or inducing, cirro-stratus and +stratus, and dropping snow. This form is called the <i>linear</i>-cirrus. The +tufted, and other fibrous forms, are seen<span class="pagenum"><a name="Page_380" id="Page_380">[Pg 380]</a></span> in patches also, in great +distinctness, during these mid-winter days, when the wind gets around to +the southward, and the weather is pleasant. Such days are called +“<i>weather-breeders</i>,” and their <i>offspring</i> the patches of cirrus, which +are to extend and compose, or induce the storm, and indeed are an advance +part of it, are then never absent. A clear, moderate day, in a normal +winter, with wind from any southern point, however light, between the 1st +of January and the middle of February, without these patches of cirrus, is +very uncommon. Watch and see whether they tend to cirro-stratus, or +whether the wind gets around to the N. W. at nightfall, and they +disappear. If the former, a storm may be expected; if the latter, fair +weather.</p> + +<p>Thus there are three peculiarities attending the forming cirrus of +mid-winter (1st of January to 10th of February): long, fibrous, parallel +bands in the morning (linear cirrus), gradually coalescing as the day +advances, after severe cold; the comoid, curled, or tufted cirrus, in +curling bunches, called “<i>mares’-tails</i>,” and the <i>transverse</i>, when the +fibers are in bands or threads, which are not parallel, but cross each +other at angles, more or less acute. The two former varieties are +represented on Figure 5, page <a href="#Page_27">26</a>, indicated by one bird, but the last form +is a very prevalent one in our atmosphere.</p> + +<p>Various names have been given to different forms of <i>cirro-stratus</i>. Those +represented in Figure 5, page <a href="#Page_27">26</a>, are the “<i>cymoid</i>” on the right, the +“<i>mottled</i>” on the left, below the cirro-cumulus; and the “<i>linear</i>”<span class="pagenum"><a name="Page_381" id="Page_381">[Pg 381]</a></span> +below that. The form known as the “<i>mackerel sky</i>” is not represented +there. It consists of regular forms, resembling the <i>waves</i> on the surface +of the water when the wind blows a gentle breeze. But the <i>wavy</i> form, and +of all sizes, is very frequently assumed by cirro-stratus, which is +rapidly condensing, and turning to stratus. In the “mackerel sky,” +strictly so called, the waves are small, parallel, nearly distinct and +equi-distant, and resembling the appearance of a school of mackerel, +swimming in the same direction, one above another. All <i>wavy</i> forms of +cirro-stratus indicate a disposition to increased condensation and rain. +When the waves are very large and dense, and cross obliquely, or unite at +one end, rain is very certain to fall soon, if the line of progress of the +condensation is over the observer, and the clouds are seen in the western +or N. W. quarter of the sky.</p> + +<p>But there are few forms which are not occasionally seen when no rain or +snow falls. The intensity of the electric action which produces them may +not be sufficient to effect precipitation, or they may be the attendant, +attenuated <i>lateral</i> condensation, which frequently “thins out” a +considerable distance from the dense, precipitating portions of the storm.</p> + +<p>If that denser portion is north of us, the probabilities of rain are +greater, for there is always a probability that the storm may be of the +character which is extended south, by a polar wave. The observer must +watch the formation of cirri, and the different forms of cirro-stratus and +stratus, and become familiar with their appearance. It is not a difficult +task.<span class="pagenum"><a name="Page_382" id="Page_382">[Pg 382]</a></span> With the aid of a few general directions he will soon be familiar +with them:</p> + +<p>1. Get a correct idea of the different characters of the primary clouds. +The true fibrous <i>cirrus</i>—the different forms of <i>cirro-stratus</i>—the +smooth, uniform <i>stratus</i>—the <i>cirro-cumulus</i>, which is nothing but a +cirro-stratus, separated into <i>distinct masses</i> by the repulsion of static +electricity—and the <i>cumulus</i>, too distinct ever to be mistaken. There is +no difficulty, except with the varied forms of cirro-stratus. It is +useless to attempt to give, or the observer to rely on, names for these +numerous forms, without as numerous illustrations. Those in use are rarely +applied correctly. I have never met with ten persons who applied even the +term “mackerel sky” to the same precise form of cirro-stratus. In relation +to all of them it is to be observed that polar belts of condensation, and +local appearances of considerable extent, are often too feeble in action +to precipitate, even when the mackerel form is present; and all may be the +lateral attendants of passing storms. Therefore,</p> + +<p>2. Satisfy yourself whether the cirrus or cirro-stratus increases in +density and tends to the formation, or induction, of stratus; and whether +it is isolated, or an extension of the condensation of a storm, and if the +latter, <i>where that storm is</i>. The time will come when an intelligent use +of the telegraph will do this for you.</p> + +<p>3. Look also to the character of the wind, if there be any. On this +subject I have perhaps said all<span class="pagenum"><a name="Page_383" id="Page_383">[Pg 383]</a></span> that is necessary in the preceding pages. +Next to condensation, the direction and character of the wind is the most +valuable prognostic. Indeed it often tells us that a storm is approaching, +and the quarter from which it will come, and its character, before the +condensation is visible.</p> + +<p>4. See if there is any <i>secondary</i> condensation or scud. These are +sometimes seen running toward a storm, when there are not distinct clouds +visible in the western horizon, at nightfall, or in the evening, as in the +instance stated in the introduction, and sometimes from the north-east, as +in cases heretofore so often stated. But the easterly scud do not often +form in winter, until after the cirrus has passed into the form of +cirro-stratus, or has induced the latter forms in the inferior portion of +the trade, or the surface atmosphere.</p> + +<p>The inductive effect of the primary condensation, therefore, is not +always, and especially in winter, sufficient to create the easterly +current and scud, and it is often the case that the easterly wind is not +felt, or the scud seen, in snow-storms, until the snow has begun to fall, +and the first snow will fall with a S. W. air, as I have heretofore +stated. But when the condensation has so far advanced toward stratus that +the easterly wind and scud are obvious, there is little or no doubt that +rain or snow will fall speedily. The occasional occurrence of easterly +wind and scud, without rain, however—dry north-easters, as I have termed +them—in connection with storms passing south of us, or condensation too +feeble to precipitate,<span class="pagenum"><a name="Page_384" id="Page_384">[Pg 384]</a></span> should be remembered. The long, dry, +north-easterly winds of spring have been attributed to the icebergs, but +they are overlaid by feeble stratus or cirro-stratus condensation, or are +the result of attraction, by a more southern precipitation. The observer +must be careful to distinguish between the various forms of N. W. scud and +cirro-stratus, which they sometimes resemble. This he may do <i>from the +direction in which they move</i>. Cirro-stratus always moves from some point +between S. S. W. and W. S. W. to some point between N. N. E. and E. N. E. +The various forms of N. W. scud move to the S. E. The March, foggy scud, +from between W. and N. W., rarely have any cirro-stratus above them, but +rather a peculiar turbid condensation.</p> + +<p>The character of the primary condensation, the direction and force of the +wind, and the direction of the secondary condensation or scud, must be the +main reliance of the observer. But I must reiterate that they all differ +in different kinds of storms, in different seasons of the same year, and +the same seasons of different years; and the observer must be careful to +make due allowance for those differences.</p> + +<p>There are, however, divers other secondary signs, which, although not +alone to be relied upon, will aid the observer, if carefully studied, when +the character of the clouds, and the pressure of easterly or southerly +wind and scud, are not decisive. Of these, a large class are electrical.</p> + +<p>The smoke descends the adjoining chimney-flues, or outside of the chimney, +toward the ground.</p> + +<p><span class="pagenum"><a name="Page_385" id="Page_385">[Pg 385]</a></span>Thus, Darwin, as quoted by Hone:</p> + +<p class="poem">“The smoke from chimneys right ascends,<br /> +Then, <i>spreading</i>, back to earth it bends.”</p> + +<p>Smoke is electrified <i>positively</i>, by the act of combustion; the earth and +the adjacent atmosphere, when storms are gathering or approaching, is +<i>negative</i>. Hence the smoke spreads, and is attracted downward by an +opposite electricity. On the other hand, it is interesting to see, at +other times, and when the difference in temperature is not material, but +the whole atmosphere is positive, with what rapidity and compactness the +smoke will ascend in a <i>straight and elevated column</i> from the chimney, +repelled by a similar electricity. I am aware it is generally supposed the +smoke descends because the <i>air is lighter</i>. But it is a mistake. I have +seen it descend when the barometer was at 30°.60, or .60 above the mean.</p> + +<p>There is, too, a draught downward in chimneys, in such cases when there is +no smoke or fire in any of its flues. Thus Jenner says: “The soot falls +down;” whether he meant by this that there was an actual fall of soot +other than what is occasioned by the rain falling in through the chimney +top, and disturbing the soot, as sometimes happens, I do not know. It +occurs rarely, and is of very little practical importance. But every +housewife knows that chimneys, which have been used in winter, and are +full of soot, <i>smell</i> before storms. The odor results from a downward +draught and the dampness of the air. So the smoke from one flue will +descend<span class="pagenum"><a name="Page_386" id="Page_386">[Pg 386]</a></span> another, into some unused room, on such occasions. Another class +of these electrical signs are felt by those who are suffering from chronic +diseases, which have affected the nerves and made them sensitive. Thus +Jenner:</p> + +<p class="poem">“Old Betty’s joints are on the rack.”</p> + +<p>And Hone adds:</p> + +<p class="poem">“Her corns with shooting pains torment her,<br /> +And to her bed untimely send her.”</p> + +<p>But Old Betty’s rheumatism or corns are not alone in this. Those whose +bones have been broken feel it. All invalids feel it. And, indeed, all +observing healthy persons may, and do, although all are not distinctly +conscious of it. It is common for such to say, I feel sleepy, or I feel +dull, or, It <i>feels</i> like snow, or <i>feels</i> like rain, and thus from their +own feelings to be able to predict, not only falling weather, but its +<i>character</i>, whether snow or rain, at a time when either may occur +consistently with appearances.</p> + +<p>This change is a change from the positive electricity which is so +congenial to the active—“bracing” is the usual term—to negative and +damp—for this change is accompanied by condensation, as I believe all +changes from positive to negative are. Certain it is, if the atmosphere is +highly charged with negative electricity, condensation takes place; if +with positive, evaporation. Perhaps it is a change of the associated +electricity which accompanies magnetism, and not of the free atmospheric +electricity alone. Hence another phenomenon alluded to by Jenner:</p> + +<p class="poem"><span class="pagenum"><a name="Page_387" id="Page_387">[Pg 387]</a></span> +“The walls are damp, the ditches smell.”</p> + +<p>There are localities where this dampness is very obvious. The celebrated +William Cobbett, many years since, when a farmer on Long Island, observed +and published the fact that the stones grew damp before a storm. I know of +flagging stones that usually grow damp two or three hours before rain, +especially in spring and fall, and every step taken upon them is made +visible by a corresponding increase of condensation.</p> + +<p>The reverse of this takes place just before the close of storms. Flagging +stones, and walls under cover, will frequently become dry before the rain +ceases. The negative electricity becomes less as the positive prevails, +although the clouds above are still dropping rain.</p> + +<p>In the comparatively moist, showery climate of England, these changes from +positive to negative alternate rapidly between successive showers; but +observations of electric phenomena, or of clouds, in that climate, are +not, without qualification, safe guides for us.</p> + +<p>So “the ditches smell,” particularly in the evening before a rain, when +the immediate surface-atmosphere is charged with negative electricity, and +the <i>condensing moisture</i> prevents the diffusion of the odors. For the +same reason the candle will not relight, and there is crackling in the +ashes or lamp. Thus, again, Virgil:</p> + +<p class="poem">“Maidens that nightly toil the tangled fleece<br /> +Divine the coming tempest; in the lamp<br /> +<i>Crackles</i> the oil, the gathering wick grows dim.”</p> + +<p><span class="pagenum"><a name="Page_388" id="Page_388">[Pg 388]</a></span>Virgil did not live in our cold climate, and knew nothing of the crackling +in the fire, or in the ashes or coals which remain after the wood is +consumed. The lamp exhibits it on a smaller scale, and perhaps he had +noticed it when in company with the maidens. But it is sometimes +noticeable even in the lamp or candle with us. A small particle of +moisture will produce it, in a marked degree, at any time.</p> + +<p>In winter, when the air is highly positive and cold, the candle can be +blown out, and by another puff of the breath relighted, with ease. But +when the electricity before a storm becomes negative, and partial +condensation takes place, this can not be done. This partial condensation +before storms and showers shows itself upon vessels containing cold-water, +in summer. It seems to be the received opinion, that the condensation is +evidence of a greater <i>quantity</i> of moisture in the atmosphere. But this, +too, is a mistake, and hence the little reliance to be placed on +hygrometers.</p> + +<p>This partial condensation is sometimes visible. When the sun shines +clearly, at the east or west, through a <i>small opening</i> in the clouds, the +condensing vapor is shown by the streaks of sunlight, just as the fine +particles of dust are seen in a dark room, when a few rays of sunlight are +admitted through a small aperture. This phenomenon is often observed, and +it is said of it—“It’s a going to rain; <i>the sun is drawing water</i>.”</p> + +<p>Virgil alludes to this as seen in the east in the morning, thus:</p> + +<p class="poem"><span class="pagenum"><a name="Page_389" id="Page_389">[Pg 389]</a></span> +“But when beneath the dawn <i>red-fingered rays</i><br /> +Through the dense band of clouds <i>diverging</i> break,<br /> +<span class="spacer">*</span><span class="spacer">*</span><span class="spacer">*</span><span class="spacer">*</span><span class="spacer">*</span><span class="spacer">*</span><span class="spacer">*</span><br /> +Ill does the leaf defend the mellowing grape;<br /> +Leaps on the noisy roof the plenteous hail,<br /> +Fearfully crackling.”</p> + +<p>It is well ascertained that storm-clouds of great intensity have polarity +in the different portions, and that in the less intense magneto-electrical +climate of England isolated showers are often of this character—the +polarity existing in rings. Showers are doubtless thus found with us. Mr. +Wise got into one of them; see his description (Theory and Practice of +Aeronautics page 240).</p> + +<p>I have, in another place, alluded to the upward attraction of the dust +beneath the advance condensation of a shower. Jenner alludes to it in the +following lines:</p> + +<p class="poem">“The whirling winds the <i>dust</i> obeys,<br /> +And in the rapid eddy plays.”</p> + +<p>So Virgil:</p> + +<p class="poem">“Light chaff and leaflets, <i>flitting, fill the air</i>,<br /> +And sportive feathers circle on the lake.”</p> + +<p>All these are electrical.</p> + +<p>In England, where the action of such isolated clouds is less intense, the +different electricities in different portions of the cloud, whose opposite +and changing action produce all the phenomena, the condensation, the cold +and congelation, the currents, etc., have been accurately ascertained. We +can not get into the situation occupied by Mr. Wise. But every<span class="pagenum"><a name="Page_390" id="Page_390">[Pg 390]</a></span> man may +observe these <i>intestine motions</i> occasionally, in the advance +condensation of an isolated thunder-shower, in front of, but near the +smooth line of falling rain. They are more lateral than upward or +downward, and are often exceedingly rapid in movement.</p> + +<p>I have said that hail has often been found to fall from particular and +well-defined portions of a cloud, and rain from the other portions, the +hail being positive, and rain negative. An instance of very striking +character may be found in Espy’s Philosophy of Storms (Introduction, page +xx.) Doubtless in all cases thunder-showers, which are isolated and +distinct, have opposite electricity in different portions, to whose active +agency all the phenomena are owing. And the return of electricity to the +earth in the rain explains the greater fertilizing effect of the latter +compared With all artificial watering. He was a true philosopher who +attempted to stimulate vegetation by electricity.</p> + +<p>Sounds may sometimes aid the observer in doubtful cases in foretelling the +weather. The roar of the surf, or breaking of the waves on the shore, when +great bodies of water are disturbed by a precedent storm-wind, often heard +before the wind is perceived on the land, I have already alluded to. And +thus Virgil:</p> + +<p class="poem">“When storms are brooding—in the <i>leeward gulf</i><br /> +Dash the swelled waves; the mighty mountains pour<br /> +A harsh, dull murmur; far along the beach<br /> +Rolls the deep rushing roar.”</p> + +<p><span class="pagenum"><a name="Page_391" id="Page_391">[Pg 391]</a></span>The moaning or whistling of the wind all have noticed. It is not uncommon +to hear the expression, “The wind sounds like rain.” Jenner says:</p> + +<p class="poem">“The <i>hollow</i> winds begin to blow.”</p> + +<p>And Virgil:</p> + +<p class="poem">“The <i>whispering</i> grove<br /> +Betrays the gathering elemental strife.”</p> + +<p>This whispering is the motion of the leaves; and they are often stirred by +a peculiar motion which is not that of wind. Sometimes every leaf upon a +tree may be seen <i>vibrating</i> with an <i>upward and downward</i> motion, when +there is not wind enough to stir a twig. This interesting phenomenon is +electrical. Trees, and all vegetables, confessedly discharge electricity, +and such discharges move the leaves, when very active.</p> + +<p>With us, sounds can be heard more distinctly from the east or south, +before storms, according to the character of the coming wind. Howard +mentions an instance when he heard carriages five miles off. Steamboat +paddles, rail-road cars, and other sounds, are often heard a great +distance. The distance at which the now common steam-whistle is heard, and +the direction, is not an unimportant auxiliary indication of the weather. +Howard attributes these peculiar phenomena to the “<i>sounding board</i>,” made +by the <i>stratum of cloud</i>; but sounds may be heard from the north-west, +when there is no condensation, and the wind is from that quarter, and also +from the east<span class="pagenum"><a name="Page_392" id="Page_392">[Pg 392]</a></span> when it is not cloudy; and in a level country the village +bells often tell the direction of the current of air just over our heads +when we do not feel it at the surface. The wind is undoubtedly moving in a +rapid, and perhaps invisible current, not far above us. If from the east +or south, it betokens rain; if from the western quarter, fair weather.</p> + +<p>The conduct of the different animals furnish a considerable portion of the +signs alluded to by Virgil and Jenner, and are never unimportant auxiliary +evidence of the approaching changes, whether from dry to wet, or wet to +dry.</p> + +<p>The observer will find, in the conduct of our birds and animals, +especially those which are not domestic, ample evidence of the truth of +the descriptions of Virgil. He denies the animals and birds foresight, but +he does not seem to have observed that the swallow leaves for the south as +soon as the <i>autumnal</i> change begins to be felt, and in August; nor the +evident sagacity of other <i>migratory</i> birds. They do not act from the +“<i>varying impulse</i>” produced by an actual state of things, but a knowledge +or apprehension of those which are to come. This is nothing more or less +than foresight. So foresight tends to prudence and skill, and they +exercise both, and with reference to the future. The goldfinch does not +build her nest in the hole of the tree, or in the crotch of the limb; but +<i>hangs it</i> with <i>exquisite skill</i> on the slender <i>waving, outward branch</i>, +where no animal, or larger bird, or any depredator, can be sustained. She +is not more timid than others; why does she invariably thus<span class="pagenum"><a name="Page_393" id="Page_393">[Pg 393]</a></span> build? What +makes her “<i>impulses</i>” differ from those of other birds, and always in the +<i>same manner</i>?</p> + +<p>Jenner, too, has grouped, in admirably descriptive language, many of the +peculiarities exhibited by animals and birds before approaching storms, +some of which exhibit foresight, and others not.</p> + +<p>Perhaps the rooster, who keeps ceaseless watch over his harem, is the most +reliable weather-watcher we have. In my earlier days, when it was the +practice to keep valuable birds of the kind much longer than it now is, +and they had opportunity to become <i>experienced</i>, it was interesting to +observe how closely they watched the weather. I well remember a venerable +chanticleer, who, perched on the tree among his hens, would always +foretell the coming storm of the morrow, by sounding forth <i>in the +evening</i>, and <i>often</i>, his defiant note. Such note in the evening was +invariable evidence of foul weather. And during the night, their earlier +and more frequent crowing is often indicative of it. It is, however, in +the earlier part of the day, in doubtful cases, that no inconsiderable +reliance may be placed on their sagacity. Often, when a storm is gathering +in the forenoon, they will announce it by an almost incessant crowing. The +habits of an <i>experienced</i>, old-fashioned bird, of this kind, will well +repay attention; but I can not answer for the Shanghai and other <i>fancy +breeds</i>.</p> + +<p>Jenner says:</p> + +<p class="poem">“The leech disturbed, is newly risen<br /> +Quite to the summit of his prison.”</p> + +<p>Few have had, or will have, opportunities to <span class="pagenum"><a name="Page_394" id="Page_394">[Pg 394]</a></span>observe this, but it is +strikingly true. It is difficult to conceive how mere condensation, from +an increase of vapor in the atmosphere, should be foreseen by the leech in +his watery prison. It is obvious, I think, there is an electric change +which reaches him, as it does the whole animal creation, the once broken +bones, and the joints of Aunt Betty. Thus much of the philosophy of signs.</p> + +<p><i>The barometer</i> is a useful instrument, in connection with observations of +the other phenomena. It is especially useful to the sailor, as its +indications relative to the winds are much the most certain. But it is +not, <i>alone</i>, to be relied upon. This is well settled, although the +reasons for it have not been understood. Why it should rise sometimes +before storms, in opposition to the general rule—or fall at others +without rain—or rise occasionally during the heaviest gales, has been a +mystery, and impaired the confidence in its accuracy and usefulness even +of the class of philosophers of whom Sir George Harvey spoke, in the +sentence quoted in the introduction. But, as I have already intimated, it +is all very intelligible.</p> + +<p>I have said that the barometer has no fair weather standard—the mean of +30 inches at the level of the sea being an <i>average</i> of the <i>fair weather</i> +elevations and the <i>foul weather</i> depressions. Its fair weather position, +it would seem, must be above the mean, therefore, and as much above as its +foul weather depressions are below. But this is not precisely true. Its +extreme fair weather range is 31 inches, and it rarely reaches that; while +its lowest storm range is<span class="pagenum"><a name="Page_395" id="Page_395">[Pg 395]</a></span> down to 28, and is the most often reached of +the two. My barometer stands about 40 feet above ordinary high-water mark. +It is not a “wheel,” but an open, “scale” barometer, and a perfectly good +one. Its most reliable fair weather standard is about 30<span style="font-size: 0.8em;"><sup>30</sup></span>⁄<span style="font-size: 0.6em;">100</span> inches. It +is its <i>most common summer, set fair position</i>, but that position is often +at other and different elevations, at other periods of the year, during +fair weather. The reader must observe for his own locality, and satisfy +himself what the most common set fair position for the barometer is, at +the different periods of the year, where he resides. When he has +ascertained this, he may apply the following principles to illustrate its +exceptional action, and in judging of the future of the weather:</p> + +<p>1st. <i>As to its rise before storms.</i>—Supposing it to have been +stationary, at or about a set fair position, <i>for the period</i>, and for one +or two or more days, a very <i>gradual</i> and <i>moderate</i> rise is an indication +of continued fair weather; and a <i>sudden</i> and <i>considerable rise</i> is +indicative of a storm. If the sudden and considerable rise occurs in the +latter part of spring, summer, or early autumn, it indicates a storm of +the <i>first</i> or <i>third classes</i> described in Chapter X., if in winter, a +storm of the <i>first class</i> only. If the elevation is <i>very</i> sudden and +considerable, the storm will probably be <i>severe</i>. The philosophy of this, +according to my present apprehension of it, is, that these storms present +an <i>extended easterly front</i>—<i>settle very near the earth</i>—and <i>have a +rapid progress</i>—thus accumulating the atmosphere somewhat, in advance of +them.</p> + +<p><span class="pagenum"><a name="Page_396" id="Page_396">[Pg 396]</a></span>2d. <i>As to its fall before storms without previous rise.</i>—This is always +very regular before the second class of storms, or polar belts of showers +and storms. It is very fairly exemplified in the table from Reid, on page +329. The barometer, so far as I have opportunity to observe, does not rise +from a stationary position on the approach of this class of storms. At the +commencement of heated, summer, dry terms, my barometer has most +frequently ranged at about 30.30, and gradually, but slowly, fallen below +30 inches before the belt of showers arrived, and the term closed. The +fourth rule of Dalton (Meteorology, page 183) indicates a similar law in +England. It is as follows:</p> + +<div class="blockquot"><p>“In summer, after a long continuance of fair weather, with the +barometer high, it generally falls gradually, and for one, two, or +more days, before there is much appearance of rain. If the fall be +sudden and great for the season, it will probably be followed by +thunder.”</p></div> + +<p>3d. <i>It falls frequently and considerably without rain.</i>—This is owing to +the fact that <i>all</i> regular, periodic efforts at condensation do not +result in rain. The second, third, and fourth classes of storms described, +may not (as we have said) <i>be sufficiently active to precipitate</i>, +although the <i>series of phenomena</i> (including the fall of the barometer) +may be, in other respects, perfect. Such an instance may be found in +Reid’s table, on page 329, and on the 11th of the month. But the fall in +such cases is not as great, unless the wind be violent.</p> + +<p>4th. <i>It rises during considerable gales.</i>—But these<span class="pagenum"><a name="Page_397" id="Page_397">[Pg 397]</a></span> are of the kind so +often alluded to—viz., the N. W., in the northern hemisphere, and the S. +W., in the southern; and the <i>philosophy</i> of it has been explained, and is +observable.</p> + +<p>With these explanations, the reader will be able to understand, and +practically apply, the barometric changes, in connection with the other +phenomena, in forming an opinion of the weather.</p> + +<p><i>The thermometer</i> is also an auxiliary. It <i>rises</i>, during the winter half +of the year, in the <i>advance portion of the storm</i>, and falls when it +passes off again; and the reverse is true, as we have seen, when its range +is very high in summer. It is, therefore, to some extent, a useful +auxiliary, although of minor importance.</p> + +<p><i>The hygrometer</i> is of less importance still. It is not in general use as +a practical guide to the changes of the weather, and does not deserve to +be.</p> + +<p>A question, which has been much mooted, deserves a passing notice in this +connection—viz., whether our climate has gradually become ameliorated and +milder on the eastern part of our continent, since its settlement. I have +not space left for its discussion. Humboldt (Aspects of Nature, page 103) +is of opinion that there has been no material change. He says:</p> + +<div class="blockquot"><p>“The statements so frequently advanced, although unsupported by +measurements, that since the first European settlements in New +England, Pennsylvania, and Virginia, the destruction of many forests +on both sides of the Alleghanys, has rendered the climate more +equable—making the winters milder and the summers cooler—are now +generally discredited. No series of thermometric observations worthy +of confidence extend further back, in the United States, than<span class="pagenum"><a name="Page_398" id="Page_398">[Pg 398]</a></span> +seventy-eight years. We find, from the Philadelphia observations, +that from 1771 to 1824, the mean annual heat has hardly risen 2°.7 +Fahrenheit—an increase that may fairly be ascribed to the extension +of the town, its greater population, and to the numerous +steam-engines. This annual increase of temperature may also be owing +to accident, for in the same period I find that there was an increase +of the mean winter temperature of 2° Fahrenheit; but, with this +exception, the seasons had all become somewhat warmer. Thirty-three +years’ observation, at Salem, in Massachusetts, show scarcely any +difference, the mean of each one oscillating within 1° of Fahrenheit, +about the mean of the whole number; and the winters of Salem, instead +of having been rendered more mild, as conjectured, from the +eradication of the forests, have become colder, by 4° Fahrenheit, +during the last thirty-three years.”</p></div> + +<p>The facts hereinbefore stated show that there is nothing like a <i>regular</i> +amelioration; that the seasons differ during the same decade, and +different decades. The cold decade, from 1811 to 1820, has not been +reproduced. But it may be, and we know not how soon. Since that period +there has certainly been a change—for even the cold period from 1835 to +1840 did not equal that from 1815 to 1820, nor indeed those of 1775 to +1780 or 1795 to 1800. But as these variations, so far as we are enabled to +judge, depend upon the varying influence of the sun’s rays, and of +volcanic action, it is impossible to say that equally cold periods will +not return, during the latter half of this century.</p> + +<p>If the influence of the sun was constant, and volcanic action regular, two +causes would tend to modify the seasons:</p> + +<p>1st. The exposure of the surface to a more effective action of the solar +rays, by a removal of the forests, and by drainage. That such action would +be<span class="pagenum"><a name="Page_399" id="Page_399">[Pg 399]</a></span> more effective upon a surface thus uncovered and drained, can not be +doubted.</p> + +<p>2d. <i>The movement of the area of magnetic intensity, and the magnetic +pole, to the west.</i>—There is such a movement, and its progress can be +measured by the increase of declination on the east of it, and its +decrease on the west. And the effect of it on climate is unquestionable. +In all probability it has had an influence upon ours; and a removal of +that area and pole still further west—60° or 80°—would change the +location of the concentrated trade, and the Gulf Stream, and restore to +Greenland the fertility she once had, and which the Faroe Islands now +enjoy. And, on the other hand, its removal as far east of its present +position would again depopulate Greenland, and render it again +inaccessible. But I can not pursue this subject.</p> + +<p>Finally, assistance may be derived from the occasional, although +imperfect, accounts of the state of the weather elsewhere, which the +newspapers afford. I have been much indebted to the Associated Press of +New York for intelligence contained in their telegraphic reports. +Occasionally they have been very full and instructive.</p> + +<p>On this point, however, there is less of reality in the present than of +hope in the future. The time must come when the collection and +dissemination of meteorological truth, will be deemed an object of +national importance, and national duty. Population is increasing, by +immigration and propagation, in a rapidly progressive ratio. There has +been great<span class="pagenum"><a name="Page_400" id="Page_400">[Pg 400]</a></span> danger that it would outrun agricultural production. A short +crop this year would have been disastrous to our prosperity—and the +danger was imminent. Every description of business, and every financial +circle, felt that fever of anxiety it was so well calculated to induce. +The importance of extended agricultural production, and the dependence of +all classes upon its success, are now in a greater measure appreciated; +and none can fail to see the value of a correct understanding of the +weather to the agriculturist, how short-sighted soever they may be, in +relation to its direct influence upon their own prosperity and happiness.</p> + +<p>Our country is, physically, a most favored one. The facts disclosed or +alluded to in this volume show that it is without a parallel on the face +of the globe; and our facilities for meteorological observation, and the +ascertainment and practical application of meteorological truth, are +equally pre-eminent. The great extent and unbroken surface of the eastern +portion of the continent; its excessive supply of magnetism and +atmospheric currents, and the consequent marked character of the +phenomena; the existence and prospective increase of telegraph lines over +most of its surface; the homogeneous and energetic character of a +population united, upon so large a surface, under one government; the +freedom of that government from debt, and the excess of its revenue; the +possession of a National Observatory, with a competent philosopher at its +head; and a national institution, liberally endowed, and adapted to the +collection and<span class="pagenum"><a name="Page_401" id="Page_401">[Pg 401]</a></span> diffusion of practical and scientific intelligence, give +us an opportunity and a capacity for connected observation and +investigation, and an ability to profit by it, that no other nation can +boast.</p> + +<p>We have, too, a just national pride. Our exploring ships have penetrated +and made discoveries in both hemispheres, and our travelers have visited +successfully every clime; and thus our national interests, and +obligations, and pride, demand an organization, practical and permanent, +in relation to this subject, and the time will come when we shall have it.</p> + +<p>When that time comes—when the present <i>limited horizon</i> of each of us is +<i>practically extended over the entire country</i>—and when the actual state +of the weather over every part of it is known, at the same time, to the +inhabitants of every other, and every where <i>read in the light of a +correct philosophy</i>, prognostication will be comparatively simple and +certain; and <span class="smcaplc">A PROGRESS</span> will have been made, productive of an amount of +pecuniary, intellectual, and social benefit to the people, which can not +be overestimated. May it come before the shadows of the night of death +have gathered around us, that we may have a more perfect view of that +atmospheric machinery which distinguishes our planet from others, and is, +with such infinite wisdom, adapted to make it a fit habitation for man!</p> + +<p> </p> +<p class="center"><strong>THE END.</strong></p> + +<p><span class="pagenum"><a name="Page_402" id="Page_402">[Pg 402]</a></span></p> + + +<p> </p><p> </p> +<hr style="width: 50%;" /> +<p><span class="pagenum"><a name="Page_403" id="Page_403">[Pg 403]</a></span></p> +<h2>APPENDIX.</h2> + +<p>Since this work was completed I have received a very valuable publication, +entitled, the “Army Meteorological Register.” It is a compilation of the +observations made by the officers of the medical department of the army, +at the military Posts of the United States, from 1843 to 1854 inclusive, +prepared under the supervision of the Surgeon-general, and published by +direction of the Secretary of War. To this, there is appended a report or +general review of the prominent features of American climatology, so far +as the basis afforded by the published observation of the army medical +Bureau would warrant positive deduction, by Mr. Lorin Blodget, a +distinguished meteorologist, accompanied by temperature and rain charts, +for each of the four seasons;—exhibiting the various local differences +and peculiarities relative to temperature and precipitation in each.</p> + +<p>These local differences and peculiarities and contrasts are deduced and +delineated by Mr. Blodget with much ability. He was fettered, however, by +the prevailing calorific theories, and the unfortunate practice of +grouping the <ins class="correction" title="original: phenonema">phenomena</ins> into means for the seasons, Spring, Summer, Autumn, +and Winter, which grouping is arbitrary, and comparatively uninstructive. +Hence, he failed to discover what the tables and summaries most clearly +disclose—the principles and system unfolded in the foregoing work.</p> + +<p>But the summaries of this register contain observations made at posts in +Western and Southwestern Texas, in Kansas and Nebraska, and in New Mexico +and California, where there has been a dearth of such observations +hitherto, and enable me to demonstrate, more conclusively, and I think so +that none can fail to understand it, the truth of the philosophy I have +endeavored to exhibit.</p> + +<p>To do this, I will take a <i>year</i>,—divide it into two seasons, the periods +of northern and southern transit, the only natural and correct +division—and note the phenomena in each, as each progresses.</p> + +<p>And I will take the year 1854, because that is the last year for which the +record of observation is complete; because it had marked peculiarities +which are remembered; and because I have alluded to those peculiarities, +and those allusions should be confirmed or disproved by the record. Unless +I mistake exceedingly, the confirmation will be found signal and +convincing.</p> + +<p>I have assumed, pp. 187, 351, that the transits were greater in some +seasons than others; that the drought of 1854 was owing to an extreme +northern transit, or to an extension west of the concentrated +counter-trade, or both, leaving us less supplied with moisture than +usual.</p> + +<p><span class="pagenum"><a name="Page_404" id="Page_404">[Pg 404]</a></span>In point of fact, it appears from these observations that it resulted from +<i>both</i> causes, operating <i>connectedly</i>; and the annals of Science rarely +furnish a more striking instance of analogical inference proved true by +subsequent investigation.</p> + +<p>Commencing then with the commencement of the northern transit about the +1st of February, we are enabled to trace the then location of our +concentrated trade, and its subsequent progress to the north till August, +and its influence upon temperature and precipitation. And we can also +trace the situation during the same period, of the intervening drought, +and the inter-tropical belt of rains, and the extension of the latter +north over Florida and the cotton-planting States.</p> + +<p>On the 1st of February, 1854, our counter-trade was somewhat more +concentrated on its extreme winter curve, over the Southern States, than +usual. Its line of excess reached up from Fort Brooke, on the peninsula of +Florida, to the northwest, a little east of Pensacola on the gulf, cutting +Mount Vernon Arsenal north of Pensacola, and extending thence +north-westwardly on to Eastern Louisiana, and curving thence and passing +N. E. or E. N. E., to the Atlantic, about the waters of the Chesapeake +Bay. It thinned out to the west over New Orleans and Baton Rouge, +supplying them moderately, but did not extend to the forts of Texas on the +west, nor the posts in the Indian Territory at the N. W. It was east of +Fort Towson, which is the south-eastern one. It did not reach St. Louis on +the north, nor extend north of the Ohio River, as will appear from the +tables hereinafter given. The following cut shows substantially its +situation on the 1st of February.</p> + +<p> </p> +<div class="figcenter"><img src="images/i0429.jpg" alt="" /></div> +<p> </p> + +<p>Now, during the month of January, we find the following state of things. +<i>Under</i> this concentrated trade, the temperature was above the mean, even +if Forts Monroe and McHenry on the Atlantic are included; but Mr. Blodget +discredits their returns, and some others which do<span class="pagenum"><a name="Page_405" id="Page_405">[Pg 405]</a></span> not conform to general +results. On the west and north of its curving line, both precipitation and +temperature were below the mean.</p> + +<p>Under the counter trade, we have the following stations, with their actual +and mean temperature. I have inserted the temperature for several +subsequent months, to show a depression in April.</p> + +<p> </p> +<p class="center">TABLE I.</p> + +<table border="0" cellpadding="0" cellspacing="0" summary="table"> +<tr><td class="btr"> </td> + <td class="btr" align="center">LAT.</td> + <td class="btr" align="center">LON.</td> + <td class="btr" align="center">JAN.</td> + <td class="btr" align="center">FEB.</td> + <td class="btr" align="center">MAR.</td> + <td class="btr" align="center">APRIL.</td> + <td class="btr" align="center">MAY.</td> + <td class="btr" align="center">JUNE.</td> + <td class="bt" align="center">JULY.</td></tr> +<tr><td class="btr">Fort Moultrie</td> + <td class="btr" align="center">32.45</td> + <td class="btr" align="center">79.51</td> + <td class="btr" align="center"><b>50.83</b></td> + <td class="btr" align="center">53.09</td> + <td class="btr" align="center">62.72</td> + <td class="btr" align="center">62.76</td> + <td class="btr" align="center">73.35</td> + <td class="btr" align="center">78.55</td> + <td class="bt" align="center">82.06</td></tr> +<tr><td class="br"><span style="margin-left: 1em;">Mean of 28 yrs.</span></td> + <td class="br" align="center"> </td> + <td class="br" align="center"> </td> + <td class="br" align="center">50.36</td> + <td class="br" align="center">52.41</td> + <td class="br" align="center">58.68</td> + <td class="br" align="center">65.44</td> + <td class="br" align="center">73.42</td> + <td class="br" align="center">79.01</td> + <td class="dent" align="center">81.72</td></tr> +<tr><td class="br">Fort Pierce</td> + <td class="br" align="center">27.30</td> + <td class="br" align="center">80.20</td> + <td class="br" align="center"><b>67.91</b></td> + <td class="br" align="center">67.33</td> + <td class="br" align="center">73.01</td> + <td class="br" align="center">71.10</td> + <td class="br" align="center">78.41</td> + <td class="br" align="center">82.09</td> + <td class="dent" align="center">84.16</td></tr> +<tr><td class="br"><span style="margin-left: 1em;">Mean of 5 yrs.</span></td> + <td class="br" align="center"> </td> + <td class="br" align="center"> </td> + <td class="br" align="center">62.75</td> + <td class="br" align="center">64.42</td> + <td class="br" align="center">69.77</td> + <td class="br" align="center">73.63</td> + <td class="br" align="center">76.92</td> + <td class="br" align="center">79.02</td> + <td class="dent" align="center">82.50</td></tr> +<tr><td class="br">Fort Meade</td> + <td class="br" align="center">28.01</td> + <td class="br" align="center">82.00</td> + <td class="br" align="center"><b>63.75</b></td> + <td class="br" align="center">63.33</td> + <td class="br" align="center">70.64</td> + <td class="br" align="center">68.10</td> + <td class="br" align="center">76.31</td> + <td class="br" align="center">79.10</td> + <td class="dent" align="center">80.17</td></tr> +<tr><td class="br"><span style="margin-left: 1em;">Mean of 3 yrs.</span></td> + <td class="br" align="center"> </td> + <td class="br" align="center"> </td> + <td class="br" align="center">58.40</td> + <td class="br" align="center">63.23</td> + <td class="br" align="center">69.02</td> + <td class="br" align="center">69.89</td> + <td class="br" align="center">76.69</td> + <td class="br" align="center">78.24</td> + <td class="dent" align="center">79.76</td></tr> +<tr><td class="br">Fort Brooke</td> + <td class="br" align="center">28.00</td> + <td class="br" align="center">82.28</td> + <td class="br" align="center"><b>62.94</b></td> + <td class="br" align="center">62.36</td> + <td class="br" align="center">70.06</td> + <td class="br" align="center">70.07</td> + <td class="br" align="center">77.49</td> + <td class="br" align="center">80.51</td> + <td class="dent" align="center">81.08</td></tr> +<tr><td class="br"><span style="margin-left: 1em;">Mean of 25 yrs.</span></td> + <td class="br" align="center"> </td> + <td class="br" align="center"> </td> + <td class="br" align="center">61.53</td> + <td class="br" align="center">63.54</td> + <td class="br" align="center">67.72</td> + <td class="br" align="center">71.82</td> + <td class="br" align="center">76.64</td> + <td class="br" align="center">79.46</td> + <td class="dent" align="center">80.72</td></tr> +<tr><td class="br">Fort Myers</td> + <td class="br" align="center">26.38</td> + <td class="br" align="center">82.00</td> + <td class="br" align="center"><b>67.56</b></td> + <td class="br" align="center">67.39</td> + <td class="br" align="center">73.74</td> + <td class="br" align="center">71.07</td> + <td class="br" align="center">79.13</td> + <td class="br" align="center">82.35</td> + <td class="dent" align="center">81.91</td></tr> +<tr><td class="br"><span style="margin-left: 1em;">Mean of 4 yrs.</span></td> + <td class="br" align="center"> </td> + <td class="br" align="center"> </td> + <td class="br" align="center">63.39</td> + <td class="br" align="center">67.98</td> + <td class="br" align="center">72.19</td> + <td class="br" align="center">73.86</td> + <td class="br" align="center">80.13</td> + <td class="br" align="center">81.25</td> + <td class="dent" align="center">82.87</td></tr> +<tr><td class="br">Key West</td> + <td class="br" align="center">24.32</td> + <td class="br" align="center">81.48</td> + <td class="br" align="center"><b>71.75</b></td> + <td class="br" align="center">71.95</td> + <td class="br" align="center">76.56</td> + <td class="br" align="center">73.89</td> + <td class="br" align="center">80.84</td> + <td class="br" align="center">83.34</td> + <td class="dent" align="center">83.30</td></tr> +<tr><td class="br"><span style="margin-left: 1em;">Mean of 14 yrs.</span></td> + <td class="br" align="center"> </td> + <td class="br" align="center"> </td> + <td class="br" align="center">66.68</td> + <td class="br" align="center">68.88</td> + <td class="br" align="center">72.88</td> + <td class="br" align="center">75.38</td> + <td class="br" align="center">79.10</td> + <td class="br" align="center">81.63</td> + <td class="dent" align="center">83.00</td></tr> +<tr><td class="br">Fort Barrancas</td> + <td class="br" align="center">30.18</td> + <td class="br" align="center">87.27</td> + <td class="br" align="center"><b>54.71</b></td> + <td class="br" align="center">54.56</td> + <td class="br" align="center">64.98</td> + <td class="br" align="center">62.93</td> + <td class="br" align="center">75.40</td> + <td class="br" align="center">81.00</td> + <td class="dent" align="center">84.55</td></tr> +<tr><td class="br"><span style="margin-left: 1em;">Mean of 17 yrs.</span></td> + <td class="br" align="center"> </td> + <td class="br" align="center"> </td> + <td class="br" align="center">53.61</td> + <td class="br" align="center">55.58</td> + <td class="br" align="center">61.80</td> + <td class="br" align="center">68.51</td> + <td class="br" align="center">75.45</td> + <td class="br" align="center">80.80</td> + <td class="dent" align="center">82.26</td></tr> +<tr><td class="br">Mt. Vernon Ars’l</td> + <td class="br" align="center">31.12</td> + <td class="br" align="center">88.02</td> + <td class="br" align="center"><b>51.52</b></td> + <td class="br" align="center">53.18</td> + <td class="br" align="center">65.24</td> + <td class="br" align="center">62.30</td> + <td class="br" align="center">74.64</td> + <td class="br" align="center">79.17</td> + <td class="dent" align="center">78.90</td></tr> +<tr><td class="br"><span style="margin-left: 1em;">Mean of 14 yrs.</span></td> + <td class="br" align="center"> </td> + <td class="br" align="center"> </td> + <td class="br" align="center">50.44</td> + <td class="br" align="center">53.69</td> + <td class="br" align="center">60.26</td> + <td class="br" align="center">66.87</td> + <td class="br" align="center">73.92</td> + <td class="br" align="center">78.03</td> + <td class="dent" align="center">78.62</td></tr> +<tr><td class="br">Baton Rouge</td> +<td class="br" align="center">30.26</td> + <td class="br" align="center">91.18</td> + <td class="br" align="center">53.43</td> + <td class="br" align="center">56.48</td> + <td class="br" align="center">66.24</td> + <td class="br" align="center">64.63</td> + <td class="br" align="center">75.10</td> + <td class="br" align="center">80.61</td> + <td class="dent" align="center">80.09</td></tr> +<tr><td class="bbr"><span style="margin-left: 1em;">Mean of 24 yrs.</span></td> + <td class="bbr" align="center"> </td> + <td class="bbr" align="center"> </td> + <td class="bbr" align="center">53.47</td> + <td class="bbr" align="center">55.02</td> + <td class="bbr" align="center">61.93</td> + <td class="bbr" align="center">69.30</td> + <td class="bbr" align="center">75.60</td> + <td class="bbr" align="center">80.56</td> + <td class="bb" align="center">81.81</td></tr></table> + +<p>It will be seen that the temperature was above the mean in January at +every post except Baton Rouge, and there it was at the mean. We shall see +hereafter that Baton Rouge was near its western line.</p> + +<p>Under this trade during this month, and at the same posts, the fall of +rain was as follows, compared with the mean:—</p> + +<p> </p> +<p class="center">TABLE II.</p> + +<table border="0" cellpadding="0" cellspacing="0" summary="table"> +<tr><td class="btr"> </td> + <td class="btr" colspan="2" align="center">JANUARY.</td> + <td class="btr" colspan="2" align="center">FEBR’Y.</td> + <td class="btr" colspan="2" align="center">MARCH.</td> + <td class="btr" colspan="2" align="center">APRIL.</td> + <td class="btr" colspan="2" align="center">MAY.</td> + <td class="btr" rowspan="2" valign="middle" align="center">JUNE.</td> + <td class="bt" rowspan="2" valign="middle" align="center">JULY.</td></tr> +<tr><td class="br"> </td> + <td class="btr" align="center">1854.</td> + <td class="btr" align="center">Mean.</td> + <td class="btr" align="center">1854.</td> + <td class="btr" align="center">Mean.</td> + <td class="btr" align="center">1854.</td> + <td class="btr" align="center">Mean.</td> + <td class="btr" align="center">1854.</td> + <td class="btr" align="center">Mean.</td> + <td class="btr" align="center">1854.</td> + <td class="btr" align="center">Mean.</td></tr> +<tr><td class="btr">Key West</td> + <td class="btr" align="center"><span style="margin-left: .5em;">1.77</span></td> + <td class="btr" align="center">2.86</td> + <td class="btr" align="center"><span style="margin-left: .5em;">2.55</span></td> + <td class="btr" align="center">1.38</td> + <td class="btr" align="center">0.51</td> + <td class="btr" align="center">4.21</td> + <td class="btr" align="center">2.99</td> + <td class="btr" align="center">1.55</td> + <td class="btr" align="center"><span style="margin-left: .5em;">3.14</span></td> + <td class="btr" align="center">2.58</td> + <td class="btr" align="center">4.54</td> + <td class="bt" align="center"><span style="margin-left: .5em;">3.45</span></td></tr> +<tr><td class="br">Fort Myers</td> + <td class="br" align="center"><span style="margin-left: .5em;">1.15</span></td> + <td class="br" align="center">3.90</td> + <td class="br" align="center"><span style="margin-left: .5em;">4.70</span></td> + <td class="br" align="center">2.16</td> + <td class="br" align="center">0.20</td> + <td class="br" align="center">4.60</td> + <td class="br" align="center">2.75</td> + <td class="br" align="center">3.14</td> + <td class="br" align="center"><span style="margin-left: .5em;">5.65</span></td> + <td class="br" align="center">3.33</td> + <td class="br" align="center">6.75</td> + <td class="dent" align="center"><span style="margin-left: .5em;">9.70</span></td></tr> +<tr><td class="br"><span style="margin-left: .75em;">"</span><span style="margin-left: .75em;">Brooke</span></td> + <td class="br" align="center"><span style="margin-left: .5em;">3.88</span></td> + <td class="br" align="center">2.20</td> + <td class="br" align="center"><span style="margin-left: .5em;">6.89</span></td> + <td class="br" align="center">3.01</td> + <td class="br" align="center">2.44</td> + <td class="br" align="center">3.37</td> + <td class="br" align="center">8.82</td> + <td class="br" align="center">1.95</td> + <td class="br" align="center"><span style="margin-left: .5em;">6.21</span></td> + <td class="br" align="center">3.24</td> + <td class="br" align="center">9.44</td> + <td class="dent" align="center">15.53</td></tr> +<tr><td class="br"><span style="margin-left: .75em;">"</span><span style="margin-left: .75em;">Mead</span></td> + <td class="br" align="center"><span style="margin-left: .5em;">1.30</span></td> + <td class="br" align="center">1.07</td> + <td class="br" align="center"><span style="margin-left: .5em;">2.21</span></td> + <td class="br" align="center">1.01</td> + <td class="br" align="center">1.85</td> + <td class="br" align="center">1.64</td> + <td class="br" align="center">3.19</td> + <td class="br" align="center">1.78</td> + <td class="br" align="center">10.51</td> + <td class="br" align="center">5.34</td> + <td class="br" align="center">7.24</td> + <td class="dent" align="center"><span style="margin-left: .5em;">8.55</span></td></tr> +<tr><td class="br"><span style="margin-left: .75em;">"</span><span style="margin-left: .75em;">Pierce</span></td> + <td class="br" align="center"><span style="margin-left: .5em;">3.55</span></td> + <td class="br" align="center">4.45</td> + <td class="br" align="center"><span style="margin-left: .5em;">3.40</span></td> + <td class="br" align="center">2.72</td> + <td class="br" align="center">1.05</td> + <td class="br" align="center">3.01</td> + <td class="br" align="center">7.00</td> + <td class="br" align="center">3.85</td> + <td class="br" align="center"><span style="margin-left: .5em;">5.70</span></td> + <td class="br" align="center">4.27</td> + <td class="br" align="center">6.63</td> + <td class="dent" align="center"><span style="margin-left: .5em;">4.97</span></td></tr> +<tr><td class="br"><span style="margin-left: .75em;">"</span><span style="margin-left: .75em;">Barrancas</span></td> + <td class="br" align="center"><span style="margin-left: .5em;">3.45</span></td> + <td class="br" align="center">3.87</td> + <td class="br" align="center"><span style="margin-left: .5em;">5.55</span></td> + <td class="br" align="center">4.95</td> + <td class="br" align="center">7.21</td> + <td class="br" align="center">5.87</td> + <td class="br" align="center">0.50</td> + <td class="br" align="center">2.94</td> + <td class="br" align="center"><span style="margin-left: .5em;">3.47</span></td> + <td class="br" align="center">4.05</td> + <td class="br" align="center">3.39</td> + <td class="dent" align="center"><span style="margin-left: .5em;">5.43</span></td></tr> +<tr><td class="br">Mt. Vernon Ars’l</td> + <td class="br" align="center">11.01</td> + <td class="br" align="center">6.80</td> + <td class="br" align="center">12.83</td> + <td class="br" align="center">6.04</td> + <td class="br" align="center">6.22</td> + <td class="br" align="center">4.59</td> + <td class="br" align="center">1.96</td> + <td class="br" align="center">4.21</td> + <td class="br" align="center"><span style="margin-left: .5em;">4.45</span></td> + <td class="br" align="center">4.62</td> + <td class="br" align="center">6.72</td> + <td class="dent" align="center"><span style="margin-left: .5em;">6.13</span></td></tr> +<tr><td class="br">Baton Rouge</td> + <td class="br" align="center"><span style="margin-left: .5em;">2.85</span></td> + <td class="br" align="center">5.26</td> + <td class="br" align="center"><span style="margin-left: .5em;">5.50</span></td> + <td class="br" align="center">4.91</td> + <td class="br" align="center">6.15 </td> + <td class="br" align="center">4.68</td> + <td class="br" align="center">3.58</td> + <td class="br" align="center">5.22</td> + <td class="br" align="center"><span style="margin-left: .5em;">8.05</span></td> + <td class="br" align="center">5.18</td> + <td class="br" align="center">4.00</td> + <td class="dent" align="center"><span style="margin-left: .5em;">6.55</span></td></tr> +<tr><td class="bbr">Fort Moultrie</td> + <td class="bbr" align="center"><span style="margin-left: .5em;">3.80</span></td> + <td class="bbr" align="center">2.39</td> + <td class="bbr" align="center"><span style="margin-left: .5em;">2.84</span></td> + <td class="bbr" align="center">2.33</td> + <td class="bbr" align="center">0.25</td> + <td class="bbr" align="center">4.06</td> + <td class="bbr" align="center">2.20</td> + <td class="bbr" align="center">1.75</td> + <td class="bbr" align="center"><span style="margin-left: .5em;">3.70</span></td> + <td class="bbr" align="center">4.08</td> + <td class="bbr" align="center">4.20</td> + <td class="bb" align="center"><span style="margin-left: .5em;">5.69</span></td></tr></table> + + +<p>It will be observed that in February the counter-trade and extra-tropical +belt had moved up from Key West, and a drought, which sometimes intervenes +between the concentrated counter-trade and the<span class="pagenum"><a name="Page_406" id="Page_406">[Pg 406]</a></span> inter-tropical belt, +appeared there in February and March. In April, the inter-tropical belt +appeared at that point, and went on increasing till September. As the +counter-trade commenced moving north in February, an increased +precipitation above the mean commenced at all the more southern stations +under the concentrated-trade—an earnest of that irregularity which +followed, and marked the season as the most excessive of the century.</p> + +<p>In March, the intervening drought appeared at the other posts on the +peninsula, and also at Fort Moultrie, followed <i>much more closely than +usual</i>, by the inter-tropical belt of rains. In April, the drought +appeared at Fort Barrancas and Mount Vernon Arsenal (the wave of +precipitation having moved to the west), and slightly in comparison at +Baton Rouge.</p> + +<p>If now we look at the condition of things, <i>west</i> and <i>north</i> of the +curving line of concentrated trade, from Fort Brown, at the mouth of the +Rio Grande, in South-western Texas, through that State, the Indian +Territory, Arkansas, Missouri, Kentucky, and Northern Pennsylvania, to the +Atlantic, we find the thermometer every where in January below the mean. +The following table will show this, and the precipitation for that month +and February:—</p> + +<p> </p> +<p class="center">TABLE III.</p> + +<table border="0" cellpadding="0" cellspacing="0" summary="table"> +<tr><td class="btr"> </td> + <td class="btr" colspan="2" align="center">JANUARY.</td> + <td class="btr" colspan="2" align="center">FEBRUARY.</td> + <td class="btr" colspan="2" align="center">MARCH.</td> + <td class="btr" rowspan="2" align="center">Rain in<br />January.</td> + <td class="bt" rowspan="2" align="center">Rain in<br />February.</td></tr> +<tr><td class="br"> </td> + <td class="btr" align="center">1854.</td> + <td class="btr" align="center">Mean.</td> + <td class="btr" align="center">1854.</td> + <td class="btr" align="center">Mean.</td> + <td class="btr" align="center">1854.</td> + <td class="btr" align="center">Mean.</td></tr> +<tr><td class="btr" align="center"><i>Western Texas</i></td> + <td class="btr"> </td> + <td class="btr"> </td> + <td class="btr"> </td> + <td class="btr"> </td> + <td class="btr"> </td> + <td class="btr"> </td> + <td class="btr"> </td> + <td class="bt"> </td></tr> +<tr><td class="br">Fort Brown</td> + <td class="br" align="center">59.34</td> + <td class="br" align="center">60.41</td> + <td class="br" align="center">62.45</td> + <td class="br" align="center">63.63</td> + <td class="br" align="center">71.87</td> + <td class="br" align="center">68.95</td> + <td class="br" align="center">0.45</td> + <td class="dent" align="center">1.50</td></tr> +<tr><td class="br"><span style="margin-left: .75em;">"</span><span style="margin-left: .75em;">Ewell</span></td> + <td class="br" align="center">50.47</td> + <td class="br" align="center">52.92</td> + <td class="br" align="center">58.12</td> + <td class="br" align="center">57.61</td> + <td class="br" align="center">70.34</td> + <td class="br" align="center">67.00</td> + <td class="br" align="center">0.22</td> + <td class="dent" align="center">2.86</td></tr> +<tr><td class="br"><span style="margin-left: .75em;">"</span><span style="margin-left: .75em;">Inge</span></td> + <td class="br" align="center">47.24</td> + <td class="br" align="center">49.46</td> + <td class="br" align="center">56.04</td> + <td class="br" align="center">55.39</td> + <td class="br" align="center">67.54</td> + <td class="br" align="center">62.63</td> + <td class="br" align="center">0.20</td> + <td class="dent" align="center">2.15</td></tr> +<tr><td class="br" align="center"><br /><i>Indian Territory</i></td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="dent"> </td></tr> +<tr><td class="br">Fort Towson</td> + <td class="br" align="center">36.32</td> + <td class="br" align="center">43.14</td> + <td class="br" align="center">49.29</td> + <td class="br" align="center">45.97</td> + <td class="br" align="center">59.55</td> + <td class="br" align="center">53.40</td> + <td class="br" align="center">1.01</td> + <td class="dent" align="center">2.00</td></tr> +<tr><td class="br">Forts Gibson,<br /><span style="margin-left: 1em;">Washita, and</span><br /><span style="margin-left: 1em;">Arbuckle, in</span><br /><span style="margin-left: 1em;">much the same</span><br /><span style="margin-left: 1em;">proportions.</span></td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="dent"> </td></tr> +<tr><td class="br" align="center"><br /><i>Arkansas</i></td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="dent"> </td></tr> +<tr><td class="br">Fort Smith</td> + <td class="br" align="center">33.92</td> + <td class="br" align="center">40.18</td> + <td class="br" align="center">47.01</td> + <td class="br" align="center">43.89</td> + <td class="br" align="center">57.01</td> + <td class="br" align="center">51.58</td> + <td class="br" align="center">1.37</td> + <td class="dent" align="center">2.05</td></tr> +<tr><td class="br" align="center"><br /><i>Missouri</i></td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="dent"> </td></tr> +<tr><td class="br">St. Louis Arsenal</td> + <td class="br" align="center">25.47</td> + <td class="br" align="center">31.44</td> + <td class="br" align="center">36.66</td> + <td class="br" align="center">33.43</td> + <td class="br" align="center">46.10</td> + <td class="br" align="center">42.30</td> + <td class="br" align="center">0.65</td> + <td class="dent" align="center">2.40</td></tr> +<tr><td class="br" align="center"><br /><i>Kentucky</i></td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="dent"> </td></tr> +<tr><td class="br">Newport Barracks</td> + <td class="br" align="center">31.75</td> + <td class="br" align="center">34.04</td> + <td class="br" align="center">39.60</td> + <td class="br" align="center">36.94</td> + <td class="br" align="center">46.74</td> + <td class="br" align="center">45.46</td> + <td class="br" align="center">3.20</td> + <td class="dent" align="center">5.30</td></tr> +<tr><td class="br" align="center"><br /><i>Pennsylvania</i></td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="dent"> </td></tr> +<tr><td class="br">Allegheny Arsenal</td> + <td class="br" align="center">29.08</td> + <td class="br" align="center">29.25</td> + <td class="br" align="center">33.49</td> + <td class="br" align="center">31.16</td> + <td class="br" align="center">40.36</td> + <td class="br" align="center">39.02</td> + <td class="br" align="center">2.23</td> + <td class="dent" align="center">2.33</td></tr> +<tr><td class="br" align="center"><br /><i>Delaware</i></td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="dent"> </td></tr> +<tr><td class="br">Fort Delaware</td> + <td class="br" align="center">32.38</td> + <td class="br" align="center">33.67</td> + <td class="br" align="center">34.56</td> + <td class="br" align="center">35.84</td> + <td class="br" align="center">43.18</td> + <td class="br" align="center">42.90</td> + <td class="br" align="center">2.30</td> + <td class="dent" align="center">5.45</td></tr> +<tr><td class="br" align="center"><br /><i>New York Harbor</i></td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="br"> </td> + <td class="dent"> </td></tr> +<tr><td class="bbr">Fort Columbus</td> + <td class="bbr" align="center">28.71</td> + <td class="bbr" align="center">30.18</td> + <td class="bbr" align="center">28.17</td> + <td class="bbr" align="center">30.44</td> + <td class="bbr" align="center">36.17</td> + <td class="bbr" align="center">38.28</td> + <td class="bbr" align="center">2.60</td> + <td class="bb" align="center">4.00</td></tr></table> + + +<p><span class="pagenum"><a name="Page_407" id="Page_407">[Pg 407]</a></span>We find, also, from this and table first, that every where, except at Fort +Brown, and upon the Atlantic coast, the temperature had risen above the +mean in February.</p> + +<p>The situation of the belt which supplied the western coast in winter, and +its excess of precipitation, are also represented upon the cut. The +intervening area was not without counter-trade and precipitation—the +latter, of course, greatest over the area of intensity—but they were +<i>comparatively</i> less, as the tables will show.</p> + +<p>The following cut and table show the situation of the concentrated +counter-trade in March.</p> + +<p> </p> +<div class="figcenter"><img src="images/i0432.jpg" alt="" /></div> +<p> </p> + +<p class="center">TABLE IV.</p> + +<table border="0" cellpadding="0" cellspacing="0" summary="table"> +<tr><td class="btr"> </td> + <td class="btr" align="center">JAN.</td> + <td class="btr" align="center">FEBR.</td> + <td class="btr" align="center">MAR.</td> + <td class="btr" align="center">APRIL.</td> + <td class="btr" align="center">MAY.</td> + <td class="btr" align="center">JUNE.</td> + <td class="bt" align="center">JULY.</td></tr> +<tr><td class="btr">Fort Barrancas, Pensacola Bay</td> + <td class="btr" align="center">3.45</td> + <td class="btr" align="center">5.55</td> + <td class="btr" align="center"><b>7.21</b></td> + <td class="btr" align="center">0.50</td> + <td class="btr" align="center">3.47</td> + <td class="btr" align="center">3.39</td> + <td class="bt" align="center">5.43</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">3.87</td> + <td class="br" align="center">4.95</td> + <td class="br" align="center">5.87</td> + <td class="br" align="center">2.94</td> + <td class="br" align="center">4.05</td> + <td class="br" align="center">4.66</td> + <td class="dent" align="center">6.80</td></tr> +<tr><td class="br">Baton Rouge, Louisiana</td> + <td class="br" align="center">2.85</td> + <td class="br" align="center">5.50</td> + <td class="br" align="center"><b>6.15</b></td> + <td class="br" align="center">3.58</td> + <td class="br" align="center">8.05</td> + <td class="br" align="center">4.00</td> + <td class="dent" align="center">6.55</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">5.26</td> + <td class="br" align="center">4.91</td> + <td class="br" align="center">4.68</td> + <td class="br" align="center">5.22</td> + <td class="br" align="center">5.18</td> + <td class="br" align="center">5.52</td> + <td class="dent" align="center">7.42</td></tr> +<tr><td class="br">Fort Towson, Indian Territory</td> + <td class="br" align="center">1.01</td> + <td class="br" align="center">2.00</td> + <td class="br" align="center"><b>5.10</b></td> + <td class="br" align="center">2.22</td> + <td class="br" align="center">Recr’d</td> + <td class="br" align="center">stops</td> + <td class="dent" align="center">here.</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">3.13</td> + <td class="br" align="center">2.97</td> + <td class="br" align="center">4.38</td> + <td class="br" align="center">5.33</td> + <td class="br" align="center"> </td> + <td class="br" align="center"> </td> + <td class="dent" align="center"> </td></tr> +<tr><td class="br">Fort Gibson, Indian Territory</td> + <td class="br" align="center">0.30</td> + <td class="br" align="center">1.43</td> + <td class="br" align="center"><b>7.83</b></td> + <td class="br" align="center">3.16</td> + <td class="br" align="center">7.67</td> + <td class="br" align="center">2.80</td> + <td class="dent" align="center">0.21</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">1.33</td> + <td class="br" align="center">2.26</td> + <td class="br" align="center">2.54</td> + <td class="br" align="center">4.19</td> + <td class="br" align="center">4.65</td> + <td class="br" align="center">4.30</td> + <td class="dent" align="center">2.75</td></tr> +<tr><td class="br">Fort Smith, Arkansas</td> + <td class="br" align="center">1.37</td> + <td class="br" align="center">2.05</td> + <td class="br" align="center"><b>7.05</b></td> + <td class="br" align="center">6.55</td> + <td class="br" align="center">6.25</td> + <td class="br" align="center">2.26</td> + <td class="dent" align="center">1.02</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">1.96</td> + <td class="br" align="center">2.17</td> + <td class="br" align="center">2.92</td> + <td class="br" align="center">5.10</td> + <td class="br" align="center">4.46</td> + <td class="br" align="center">4.74</td> + <td class="dent" align="center">3.82</td></tr> +<tr><td class="br">St. Louis Arsenal</td> + <td class="br" align="center">0.65</td> + <td class="br" align="center">2.40</td> + <td class="br" align="center"><b>7.10</b></td> + <td class="br" align="center">4.30</td> + <td class="br" align="center">4.65</td> + <td class="br" align="center">2.20</td> + <td class="dent" align="center">1.70</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">1.93</td> + <td class="br" align="center">3.37</td> + <td class="br" align="center">3.82</td> + <td class="br" align="center">4.16</td> + <td class="br" align="center">4.88</td> + <td class="br" align="center">6.94</td> + <td class="dent" align="center">0.04</td></tr> +<tr><td class="br">Newport Barracks, Kentucky</td> + <td class="br" align="center">3.20</td> + <td class="br" align="center">5.30</td> + <td class="br" align="center"><b>8.10</b></td> + <td class="br" align="center">2.10</td> + <td class="br" align="center"> </td> + <td class="br" align="center"> </td></tr> +<tr><td class="bbr"><span style="margin-left: 3em;">(No Mean given.)</span></td> + <td class="bbr"> </td> + <td class="bbr"> </td> + <td class="bbr"> </td> + <td class="bbr"> </td> + <td class="bbr"> </td> + <td class="bbr"> </td> + <td class="bb"> </td></tr></table> + +<p><span class="pagenum"><a name="Page_408" id="Page_408">[Pg 408]</a></span>We see from this table that its focus had extended west in Florida over +Fort Barrancas, and over Baton Rouge in Louisiana; N. W. to Forts Towson +and Gibson in the Indian Territory, and Smith in Arkansas; north to St. +Louis Arsenal at St. Louis, and to Newport barracks in Kentucky; but it +was spread over a larger surface east of the mountains. Its greatest +progress for the month, was a west and north-west progress.</p> + +<p>In April, we find it had progressed rapidly west and north-west, and its +position is shown by the following cut and table.</p> + +<p> </p> +<div class="figcenter"><img src="images/i0433.jpg" alt="" /></div> +<p> </p> + +<p class="center">TABLE V.</p> + +<table border="0" cellpadding="0" cellspacing="0" summary="table"> +<tr><td class="btr"> </td> + <td class="btr" align="center">JAN.</td> + <td class="btr" align="center">FEBR.</td> + <td class="btr" align="center">MAR.</td> + <td class="btr" align="center">APRIL.</td> + <td class="btr" align="center">MAY.</td> + <td class="btr" align="center">JUNE.</td> + <td class="bt" align="center">JULY.</td></tr> +<tr><td class="btr">Fort Riley, Kansas</td> + <td class="btr" align="center">0.00</td> + <td class="btr" align="center">0.94</td> + <td class="btr" align="center">1.86</td> + <td class="btr" align="center"><b>4.55</b></td> + <td class="btr" align="center">4.35</td> + <td class="btr" align="center">1.10</td> + <td class="bt" align="center">0.00</td></tr> +<tr><td class="br">Fort Leavenworth, Kansas</td> + <td class="br" align="center">0.04</td> + <td class="br" align="center">1.78</td> + <td class="br" align="center">1.33</td> + <td class="br" align="center"><b>3.35</b></td> + <td class="br" align="center"><b>5.55</b></td> + <td class="br" align="center">4.50</td> + <td class="dent" align="center">0.18</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">0.72</td> + <td class="br" align="center">1.01</td> + <td class="br" align="center">1.61</td> + <td class="br" align="center">2.74</td> + <td class="br" align="center">3.62</td> + <td class="br" align="center">5.80</td> + <td class="dent" align="center">3.15</td></tr> +<tr><td class="br">Alleghany Arsenal, Pittsburgh</td> + <td class="br" align="center">2.23</td> + <td class="br" align="center">2.33</td> + <td class="br" align="center">2.82</td> + <td class="br" align="center"><b>4.21</b></td> + <td class="br" align="center">2.24</td> + <td class="br" align="center">2.06</td> + <td class="dent" align="center">1.45</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">2.18</td> + <td class="br" align="center">2.17</td> + <td class="br" align="center">2.70</td> + <td class="br" align="center">3.10</td> + <td class="br" align="center">3.58</td> + <td class="br" align="center">3.56</td> + <td class="dent" align="center">2.97</td></tr> +<tr><td class="br">Fort Columbus, New York Harbor</td> + <td class="br" align="center">2.60</td> + <td class="br" align="center">4.00</td> + <td class="br" align="center">0.70</td> + <td class="br" align="center"><b>8.80</b></td> + <td class="br" align="center">7.70</td> + <td class="br" align="center">2.20</td> + <td class="dent" align="center">1.90</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">2.78</td> + <td class="br" align="center">2.92</td> + <td class="br" align="center">3.44</td> + <td class="br" align="center">3.33</td> + <td class="br" align="center">4.78</td> + <td class="br" align="center">3.46</td> + <td class="dent" align="center">3.17</td></tr> +<tr><td class="br">Fort Independence, Boston</td> + <td class="br" align="center">2.50</td> + <td class="br" align="center">3.36</td> + <td class="br" align="center">2.55</td> + <td class="br" align="center"><b>5.40</b></td> + <td class="br" align="center">4.28</td> + <td class="br" align="center">2.00</td></tr> +<tr><td class="br">West Point.</td> + <td class="br" align="center">3.52</td> + <td class="br" align="center">5.04</td> + <td class="br" align="center">2.81</td> + <td class="br" align="center"><b>10.53</b></td> + <td class="br" align="center">2.00</td> + <td class="br" align="center">1.62</td></tr> +<tr><td class="bbr"><span style="margin-left: 3em;">Mean</span></td> + <td class="bbr" align="center">3.50</td> + <td class="bbr" align="center">3.44</td> + <td class="bbr" align="center">3.71</td> + <td class="bbr" align="center">4.55</td> + <td class="bbr" align="center">6.18</td> + <td class="bbr" align="center">4.79</td> + <td class="bb" align="center"> </td></tr></table> + +<p>We see, too, that both east and west of the mountains, its focus of +precipitation was one month in advance of the mean. At all the<span class="pagenum"><a name="Page_409" id="Page_409">[Pg 409]</a></span> stations +where the greatest fall was in March, it should have been in April, and +the fall at those points was greatly in excess of the usual quantity. And +the same was true of stations reached in April. The concentrated trade, +instead of spreading out, and precipitating over the whole south-eastern +portion of the continent (its normal condition), was gathered into a wave +of greater volume, resulting in greater precipitation, and was rapidly +hastening its curve to the west over Texas, and to the north-west over the +Indian Territory, and northward on its usual curve to the north and east +of them.</p> + +<p>The observations for April disclose another singular and instructive +condition. The temperature, that had every where been above the mean in +March, fell below it in April under the concentrated trade. And snow fell +on three days in some localities, and four in others.</p> + +<p>Along the Ohio River, it fell to the depth of 8 to 10 inches on the 17th, +and east of the mountains to a greater depth on the 18th, one day later. +It fell to the depth of 4 inches at Marietta on the 29th also. Dr. +Hilldreth, American Journal of Science for March, 1855, says:—</p> + +<p>“It is a singular fact that the deepest snow, 8 inches, fell on the 17th +of April, and at the head waters about Pittsburg over a foot. Also, on the +29th of the month, at Marietta, 4 inches, a very rare occurrence.” This +depression of the temperature was quite general, but the fall of snow was +local. The latter was north of a line drawn from Fort Laramie, at the base +of the Rocky Mountains, in an E. S. E. direction—north of Forts Kearney +and Leavenworth, and of St. Louis, but south of Newport barracks in +Kentucky, and from thence to the Atlantic. Snow fell at every station +north of this line, at no station south of it. The depression of +temperature, however, was experienced over the continent, east of the +Rocky Mountains, under, and south of, the belt of precipitation. Now what +occasioned this general depression of temperature, and local fall of snow? +It will not do to say, as perhaps some calorific theorist may be inclined +to say, because the concentrated trade had been carried up where it was +cold, a month too soon; or that the sun had heated the land in advance of +it, and drawn it up.</p> + +<p>For, 1st, it might be asked how, if it was warm enough to draw it up, +could it be cold enough to make it snow; or, 2d, how happened it to start, +when, as we have seen, it was warmer than the mean under it, and colder +than the mean to the north and west of it, when it commenced its journey?</p> + +<p>But again, it snowed at posts north of the line, while the thermometer +remained above the mean; and the thermometer fell below the mean down to +Fort Brown in south-western Texas, and at Key West in the southern part of +Florida; and what is more remarkable still, at Key West, Fort Barrancas, +and every other south-eastern station, except Forts Brooke and Moultrie, +it not only fell below the <i>mean</i> of the month, but <i>below the actual +temperature of March</i>. (See <a href="#Page_405">Table I</a>.) At Forts Brooke and Moultrie it did +not rise above that temperature. West of the Rocky Mountains the +depression was not felt; nor at stations north, or north-west of the belt +of precipitation.</p> + +<p>It is obvious, the <ins class="correction" title="original: calorifice">calorific</ins> theory can furnish no rational explanation of +this matter; for the reason that, whatever the cause, it operated<span class="pagenum"><a name="Page_410" id="Page_410">[Pg 410]</a></span> not +only under, but south, and far south of the belt of precipitation. It +could not have been spots upon the sun, or other general cause, for then +it would have operated in New Mexico and California, and at the +north-western stations. It operated most intensely in Florida and the +South-Eastern States, which approach most nearly the volcanic areas of +South America and the West Indies. I believe it to have been occasioned by +volcanic action affecting the local magnetism of our intense area; but it +is a most important development, and should be thoroughly investigated. We +may find in it the key to the mysterious, but unquestionable, influence of +volcanic upon magnetic action; and I hope the distinguished +surgeon-general will cause the records of that month to be published “in +extenso.”</p> + +<p>In May and June, the trade became more concentrated, a perfectly developed +belt from the Rio Grande to the Lakes and British possessions, and +doubtless to the Atlantic, with every where a central focus of excessive +precipitation, gathering to itself in one vast wave the current that +should have been spread out over the whole country; and leaving every +where on its eastern and southern borders, down to the northern edge of +the inter-tropical belt of rains—(which extended up to lines drawn from +Baton Rouge to Charleston)—a <i>perfectly well developed</i> and <i>defined +drought</i>. That drought will long be remembered. The following cuts show, +approximately, the location of the belt of precipitation and drought for +those months, and the table which follows will show their correctness.</p> + +<p>The tables also show that this wave was occasionally a double, or divided +one—evinced by an intervening <i>partial</i> precipitation. Tables IV., V., +and VI., also show the commencement of the drought at the several +stations, as the wave moved to the west and north.</p> + +<p> </p> +<p class="center"><strong>MAY.</strong></p> +<div class="figcenter"><img src="images/i0435.jpg" alt="" /></div> +<p> </p> +<p><span class="pagenum"><a name="Page_411" id="Page_411">[Pg 411]</a></span></p> +<div class="figcenter"><img src="images/i0436.jpg" alt="" /></div> +<p> </p> + +<p class="center">TABLE VI.</p> + +<table border="0" cellpadding="0" cellspacing="0" summary="table"> +<tr><td class="btr"> </td> + <td class="btr" align="center">JAN.</td> + <td class="btr" align="center">FEBR.</td> + <td class="btr" align="center">MAR.</td> + <td class="btr" align="center">APRIL.</td> + <td class="btr" align="center">MAY.</td> + <td class="btr" align="center">JUNE.</td> + <td class="btr" align="center">JULY.</td> + <td class="btr" align="center">AUG.</td> + <td class="bt" align="center">SEPT.</td></tr> +<tr><td class="btr">Fort Brown</td> + <td class="btr" align="center">0.45</td> + <td class="btr" align="center">1.50</td> + <td class="btr" align="center">1.15</td> + <td class="btr" align="center">0.05</td> + <td class="btr" align="center">4.10</td> + <td class="btr" align="center"><b>7.65</b></td> + <td class="btr" align="center">4.25</td> + <td class="btr" align="center">5.00</td> + <td class="bt" align="center">11.31</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">1.61</td> + <td class="br" align="center">2.25</td> + <td class="br" align="center">1.20</td> + <td class="br" align="center">0.56</td> + <td class="br" align="center">2.21</td> + <td class="br" align="center">4.55</td> + <td class="br" align="center">1.95</td> + <td class="br" align="center">2.76</td> + <td class="dent" align="center">6.73</td></tr> +<tr><td class="br">Ringgold Barracks</td> + <td class="br" align="center">0.70</td> + <td class="br" align="center">1.69</td> + <td class="br" align="center">0.22</td> + <td class="br" align="center">0.00</td> + <td class="br" align="center">2.83</td> + <td class="br" align="center"><b>10.98</b></td> + <td class="br" align="center">4.06</td> + <td class="br" align="center">1.58</td> + <td class="dent" align="center">3.02</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">1.24</td> + <td class="br" align="center">1.18</td> + <td class="br" align="center">0.72</td> + <td class="br" align="center">1.08</td> + <td class="br" align="center">2.09</td> + <td class="br" align="center">3.47</td> + <td class="br" align="center">3.18</td> + <td class="br" align="center">1.50</td> + <td class="dent" align="center">3.22</td></tr> +<tr><td class="br">Fort Merrill</td> + <td class="br" align="center">0.11</td> + <td class="br" align="center">1.99</td> + <td class="br" align="center">0.05</td> + <td class="br" align="center">1.16</td> + <td class="br" align="center"><b>7.66</b></td> + <td class="br" align="center">4.70</td> + <td class="br" align="center">5.44</td> + <td class="br" align="center">3.13</td> + <td class="dent" align="center">5.01</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">0.23</td> + <td class="br" align="center">2.09</td> + <td class="br" align="center">0.09</td> + <td class="br" align="center">1.62</td> + <td class="br" align="center">3.43</td> + <td class="br" align="center">4.10</td> + <td class="br" align="center">6.13</td> + <td class="br" align="center">3.40</td> + <td class="dent" align="center">4.60</td></tr> +<tr><td class="br">Fort Duncan</td> + <td class="br" align="center">0.05</td> + <td class="br" align="center">0.69</td> + <td class="br" align="center">1.50</td> + <td class="br" align="center">0.00</td> + <td class="br" align="center">2.53</td> + <td class="br" align="center"><b>6.83</b></td> + <td class="br" align="center">0.83</td> + <td class="br" align="center">0.90</td> + <td class="dent" align="center">4.81</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">0.26</td> + <td class="br" align="center">1.27</td> + <td class="br" align="center">1.34</td> + <td class="br" align="center">0.71</td> + <td class="br" align="center">1.50</td> + <td class="br" align="center">5.63</td> + <td class="br" align="center">3.35</td> + <td class="br" align="center">0.93</td> + <td class="dent" align="center">3.28</td></tr> +<tr><td class="br">Fort Inge</td> + <td class="br" align="center">0.20</td> + <td class="br" align="center">2.15</td> + <td class="br" align="center">3.00</td> + <td class="br" align="center">0.75</td> + <td class="br" align="center"><b>3.88</b></td> + <td class="br" align="center">2.09</td> + <td class="br" align="center">0.97</td> + <td class="br" align="center">1.67</td> + <td class="dent" align="center">4.80</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">0.64</td> + <td class="br" align="center">2.21</td> + <td class="br" align="center">1.79</td> + <td class="br" align="center">1.26</td> + <td class="br" align="center">3.01</td> + <td class="br" align="center">5.38</td> + <td class="br" align="center">3.66</td> + <td class="br" align="center">2.02</td> + <td class="dent" align="center">2.21</td></tr> +<tr><td class="br">Fort McKavet</td> + <td class="br" align="center">0.01</td> + <td class="br" align="center">0.77</td> + <td class="br" align="center">2.10</td> + <td class="br" align="center">0.28</td> + <td class="br" align="center"><b>3.72</b></td> + <td class="br" align="center">0.15</td> + <td class="br" align="center">2.91</td> + <td class="br" align="center">0.04</td> + <td class="dent" align="center">3.86</td></tr> +<tr><td class="br"><span style="margin-left: .75em;">"</span><span style="margin-left: .75em;">Belknap</span></td> + <td class="br" align="center">0.11</td> + <td class="br" align="center">1.10</td> + <td class="br" align="center">1.42</td> + <td class="br" align="center">1.75</td> + <td class="br" align="center">4.97</td> + <td class="br" align="center"><b>8.33</b></td> + <td class="br" align="center">0.00</td> + <td class="br" align="center">0.75</td> + <td class="dent" align="center">1.53</td></tr> +<tr><td class="br"><span style="margin-left: .75em;">"</span><span style="margin-left: .75em;">Massachusetts,</span><br /><span style="margin-left: 2.25em;">Northern New</span><br /><span style="margin-left: 2.25em;">Mexico</span></td> + <td class="br" align="center"> </td> + <td class="br" align="center"> </td> + <td class="br" align="center"> </td> + <td class="br" align="center"> </td> + <td class="br" valign="bottom" align="center"><b>3.93</b></td> + <td class="br" valign="bottom" align="center">0.24</td> + <td class="br" valign="bottom" align="center">2.14</td> + <td class="br" valign="bottom" align="center">2.61</td> + <td class="dent" valign="bottom" align="center">1.53</td></tr> +<tr><td class="br">Fort Kearney</td> + <td class="br" align="center">0.23</td> + <td class="br" align="center">1.33</td> + <td class="br" align="center">1.87</td> + <td class="br" align="center">2.56</td> + <td class="br" align="center">4.15</td> + <td class="br" align="center"><b>5.40</b></td> + <td class="br" align="center">3.51</td> + <td class="br" align="center">1.18</td> + <td class="dent" align="center">4.60</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">0.50</td> + <td class="br" align="center">0.48</td> + <td class="br" align="center">1.55</td> + <td class="br" align="center">2.68</td> + <td class="br" align="center">6.57</td> + <td class="br" align="center">4.36</td> + <td class="br" align="center">5.07</td> + <td class="br" align="center">2.62</td> + <td class="dent" align="center">1.83</td></tr> +<tr><td class="br">Fort Laramie</td> + <td class="br" align="center">0.18</td> + <td class="br" align="center">0.40</td> + <td class="br" align="center">0.80</td> + <td class="br" align="center">3.98</td> + <td class="br" align="center"><b>4.46</b></td> + <td class="br" align="center">3.67</td> + <td class="br" align="center">3.26</td> + <td class="br" align="center">1.27</td> + <td class="dent" align="center">1.60</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">0.27</td> + <td class="br" align="center">0.71</td> + <td class="br" align="center">1.37</td> + <td class="br" align="center">1.93</td> + <td class="br" align="center">5.39</td> + <td class="br" align="center">2.95</td> + <td class="br" align="center">1.83</td> + <td class="br" align="center">0.92</td> + <td class="dent" align="center">1.33</td></tr> +<tr><td class="br">Fort Ridgley</td> + <td class="br" align="center">1.20</td> + <td class="br" align="center">0.01</td> + <td class="br" align="center">1.18</td> + <td class="br" align="center">2.83</td> + <td class="br" align="center"><b>6.84</b></td> + <td class="br" align="center">2.70</td> + <td class="br" align="center">2.49</td> + <td class="br" align="center">2.28</td> + <td class="dent" align="center">2.58</td></tr> +<tr><td class="br"><span style="margin-left: .75em;">"</span><span style="margin-left: .75em;">Snelling</span></td> + <td class="br" align="center">0.72</td> + <td class="br" align="center">0.03</td> + <td class="br" align="center">1.03</td> + <td class="br" align="center">2.51</td> + <td class="br" align="center"><b>4.30</b></td> + <td class="br" align="center">3.31</td> + <td class="br" align="center">3.92</td> + <td class="br" align="center">1.75</td> + <td class="dent" align="center">6.55</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">0.73</td> + <td class="br" align="center">0.52</td> + <td class="br" align="center">1.30</td> + <td class="br" align="center">2.14</td> + <td class="br" align="center">3.17</td> + <td class="br" align="center">3.63</td> + <td class="br" align="center">4.11</td> + <td class="br" align="center">3.18</td> + <td class="dent" align="center">3.32</td></tr> +<tr><td class="br">Fort Ripley</td> + <td class="br" align="center">0.67</td> + <td class="br" align="center">0.03</td> + <td class="br" align="center">0.79</td> + <td class="br" align="center">0.97</td> + <td class="br" align="center"><b>4.34</b></td> + <td class="br" align="center">3.68</td> + <td class="br" align="center">0.62</td> + <td class="br" align="center">1.69</td> + <td class="dent" align="center">4.40</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">0.86</td> + <td class="br" align="center">0.37</td> + <td class="br" align="center">1.80</td> + <td class="br" align="center">1.42</td> + <td class="br" align="center">3.09</td> + <td class="br" align="center">5.15</td> + <td class="br" align="center">5.20</td> + <td class="br" align="center">2.27</td> + <td class="dent" align="center">4.92</td></tr> +<tr><td class="br">Fort Mackinac</td> + <td class="br" align="center">2.59</td> + <td class="br" align="center">1.23</td> + <td class="br" align="center">1.56</td> + <td class="br" align="center">1.04</td> + <td class="br" align="center">2.65</td> + <td class="br" align="center"><b>6.35</b></td> + <td class="br" align="center">5.67</td> + <td class="br" align="center">4.26</td> + <td class="dent" align="center">3.22</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">1.25</td> + <td class="br" align="center">0.82</td> + <td class="br" align="center">1.14</td> + <td class="br" align="center">1.21</td> + <td class="br" align="center">2.32</td> + <td class="br" align="center">2.81</td> + <td class="br" align="center">3.20</td> + <td class="br" align="center">2.87</td> + <td class="dent" align="center">2.97</td></tr> +<tr><td class="br">Fort Brady</td> + <td class="br" align="center">2.49</td> + <td class="br" align="center">1.18</td> + <td class="br" align="center">1.34</td> + <td class="br" align="center">2.14</td> + <td class="br" align="center"><b>3.61</b></td> + <td class="br" align="center">1.23</td> + <td class="br" align="center">3.21</td> + <td class="br" align="center">3.86</td> + <td class="dent" align="center">3.18</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">1.84</td> + <td class="br" align="center">1.13</td> + <td class="br" align="center">1.37</td> + <td class="br" align="center">1.83</td> + <td class="br" align="center">2.24</td> + <td class="br" align="center">2.83</td> + <td class="br" align="center">3.73</td> + <td class="br" align="center">3.39</td> + <td class="dent" align="center">4.33</td></tr> +<tr><td class="br">Fort Niagara</td> + <td class="br" align="center">1.63</td> + <td class="br" align="center">2.52</td> + <td class="br" align="center">1.87</td> + <td class="br" align="center">2.25</td> + <td class="br" align="center">3.90</td> + <td class="br" align="center">1.71</td> + <td class="br" align="center">4.08</td> + <td class="br" align="center">1.52</td> + <td class="dent" align="center">2.61</td></tr> +<tr><td class="bbr"><span style="margin-left: 3em;">Mean</span></td> + <td class="bbr" align="center">2.25</td> + <td class="bbr" align="center">1.89</td> + <td class="bbr" align="center">2.12</td> + <td class="bbr" align="center">2.20</td> + <td class="bbr" align="center">2.55</td> + <td class="bbr" align="center">3.28</td> + <td class="bbr" align="center">3.49</td> + <td class="bbr" align="center">3.04</td> + <td class="bb" align="center">3.95</td></tr></table> + +<p><span class="pagenum"><a name="Page_412" id="Page_412">[Pg 412]</a></span>But the belt of trade continued its progress to the west and north, and +during the months of July and August the drought extended in both +directions, reaching, in August, from Mississippi, Alabama, Georgia, and +South Carolina, to the Lakes, and from the Rocky Mountains to the +Atlantic. Its position is shown by the following cut, and the position of +the belt of precipitation by the following table.</p> + +<p> </p> +<div class="figcenter"><img src="images/i0437.jpg" alt="" /></div> +<p> </p> + +<p class="center">TABLE VII.</p> + +<p class="center"><i>Situation of the focus of Precipitation in July and August.</i></p> + +<table border="0" cellpadding="0" cellspacing="0" summary="table"> +<tr><td class="btr"> </td> + <td class="btr" align="center">JUNE.</td> + <td class="btr" align="center">JULY.</td> + <td class="btr" align="center">AUG.</td> + <td class="btr" align="center">SEPT.</td> + <td class="bt" align="center">OCT.</td></tr> +<tr><td class="btr" align="center"><i>New Mexico.</i></td> + <td class="btr" align="center"> </td> + <td class="btr" align="center"> </td> + <td class="btr" align="center"> </td> + <td class="btr" align="center"> </td> + <td class="bt" align="center"> </td></tr> +<tr><td class="br">Fort Thorne</td> + <td class="br" align="center">0.08</td> + <td class="br" align="center">2.23</td> + <td class="br" align="center">6.01</td> + <td class="br" align="center">3.50</td> + <td class="dent" align="center">0.00</td></tr> +<tr><td class="br">Albuquerque</td> + <td class="br" align="center">0.28</td> + <td class="br" align="center">2.50</td> + <td class="br" align="center">1.19</td> + <td class="br" align="center">2.67</td> + <td class="dent" align="center">1.37</td></tr> +<tr><td class="br">Santa Fe</td> + <td class="br" align="center">0.32</td> + <td class="br" align="center">4.11</td> + <td class="br" align="center">3.86</td> + <td class="br" align="center">4.06</td> + <td class="dent" align="center">2.50</td></tr> +<tr><td class="br">Fort Defiance</td> + <td class="br" align="center">1.24</td> + <td class="br" align="center">3.94</td> + <td class="br" align="center">5.24</td> + <td class="br" align="center">3.47</td> + <td class="dent" align="center">0.62</td></tr> +<tr><td class="br"><span style="margin-left: .75em;">"</span><span style="margin-left: .75em;">Yuma</span></td> + <td class="br" align="center">0.00</td> + <td class="br" align="center">0.01</td> + <td class="br" align="center">2.37</td> + <td class="br" align="center">0.17</td> + <td class="dent" align="center">0.30</td></tr> +<tr><td class="br">San Diego</td> + <td class="br" align="center">0.02</td> + <td class="br" align="center">0.07</td> + <td class="br" align="center">1.35</td> + <td class="br" align="center">0.13</td> + <td class="dent" align="center">0.01</td></tr> +<tr><td class="br">Fort Snelling, Minnesota</td> + <td class="br" align="center">3.31</td> + <td class="br" align="center">3.92</td> + <td class="br" align="center">1.75</td> + <td class="br" align="center">6.35</td> + <td class="dent" align="center">1.23</td></tr> +<tr><td class="br"><span style="margin-left: .75em;">"</span><span style="margin-left: .75em;">Brady</span></td> + <td class="br" align="center">1.23</td> + <td class="br" align="center">3.21</td> + <td class="br" align="center">3.86</td> + <td class="br" align="center">3.18</td> + <td class="dent" align="center">3.40</td></tr> +<tr><td class="bbr"><span style="margin-left: .75em;">"</span><span style="margin-left: .75em;">Mackinac</span></td> + <td class="bbr" align="center">6.35</td> + <td class="bbr" align="center">5.67</td> + <td class="bbr" align="center">4.26</td> + <td class="bbr" align="center">3.22</td> + <td class="bb" align="center">2.28</td></tr></table> + +<p>I have not space for all the comment which this exposition is calculated +to induce. The reader will not only find in it an explanation of the +extraordinary character of the summer of 1854, but will see from the +<i>means</i>, that it was but an <i>excessive development</i> of an <span class="smcap">Annual +Phenomenon,—the Progress of a Concentrated Counter-trade</span>.</p> + +<p>It is not necessary to follow with particularity the return transit.<span class="pagenum"><a name="Page_413" id="Page_413">[Pg 413]</a></span> It +required no great degree of sagacity to predict, at the time, that the +drought would continue in the vicinity of New York till about the 10th of +September. The return of the belt to that latitude, was not to be expected +before that time, and the drought continued, in fact, until the 9th of +September.</p> + +<p>Its return progress was slow, and it was every where behind time. The +autumn was warm, and so, indeed, were December and January, west of the +area of magnetic intensity, although upon, and east of it, there was a +depression in December. The retreating but lingering edge of +counter-trade, with its excess of snow for the season, caught the Iron +Horse, with its train and passengers, upon the prairies of the west, and +laid its embargoing hands upon them. Few, if any, can have forgotten the +thrilling accounts which reached us from that section, of the sufferings +endured by those who were thus embargoed for days and nights, far from the +comfortable habitations of their fellow men.</p> + +<p>But the return transit, though slow, was extreme, and February and March +were exceedingly cold for the season. The transit to the north, again, did +not commence as early as usual, and the spring was backward, and the +summer cool. Both were without irregularity, and the season was +productive. The following table exhibits the temperature on a line of +posts, running north and south at the west, during the winter months of +1855, and will illustrate what has been said.</p> + +<p> </p> +<p class="center">TABLE VIII.</p> + +<table border="0" cellpadding="0" cellspacing="0" summary="table"> +<tr><td class="btr">1855.</td> + <td class="btr" align="center">JANUARY.</td> + <td class="btr" align="center">FEBRUARY.</td> + <td class="btr" align="center">MARCH.</td> + <td class="bt" align="center">APRIL.</td></tr> +<tr><td class="btr">Key West</td> + <td class="btr" align="center">67.18</td> + <td class="btr" align="center">65.94</td> + <td class="btr" align="center">70.28</td> + <td class="bt" align="center">75.09</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">66.58</td> + <td class="br" align="center">68.88</td> + <td class="br" align="center">72.88</td> + <td class="dent" align="center">75.38</td></tr> +<tr><td class="br">Fort Snelling</td> + <td class="br" align="center">17.09</td> + <td class="br" align="center">12.62</td> + <td class="br" align="center">25.30</td> + <td class="dent" align="center">49.86</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">13.76</td> + <td class="br" align="center">17.57</td> + <td class="br" align="center">31.41</td> + <td class="dent" align="center">46.34</td></tr> +<tr><td class="br">Fort Kearney</td> + <td class="br" align="center">23.55</td> + <td class="br" align="center">25.69</td> + <td class="br" align="center">32.86</td> + <td class="dent" align="center">54.39</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">21.14</td> + <td class="br" align="center">26.11</td> + <td class="br" align="center">34.50</td> + <td class="dent" align="center">47.13</td></tr> +<tr><td class="br">Fort Laramie</td> + <td class="br" align="center">35.85</td> + <td class="br" align="center">29.01</td> + <td class="br" align="center">36.41</td> + <td class="dent" align="center">52.94</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">31.03</td> + <td class="br" align="center">32.60</td> + <td class="br" align="center">36.81</td> + <td class="dent" align="center">47.60</td></tr> +<tr><td class="br">Fort Arbuckle</td> + <td class="br" align="center">41.94</td> + <td class="br" align="center">39.86</td> + <td class="br" align="center">49.09</td> + <td class="dent" align="center">67.43</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">39.10</td> + <td class="br" align="center">43.69</td> + <td class="br" align="center">53.22</td> + <td class="dent" align="center">61.85</td></tr> +<tr><td class="br">Fort Belknap</td> + <td class="br" align="center">45.92</td> + <td class="br" align="center">44.49</td> + <td class="br" align="center">53.09</td> + <td class="dent" align="center">70.00</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">42.80</td> + <td class="br" align="center">47.47</td> + <td class="br" align="center">56.90</td> + <td class="dent" align="center">65.79</td></tr> +<tr><td class="br">Fort Chadbourne</td> + <td class="br" align="center">48.89</td> + <td class="br" align="center">45.87</td> + <td class="br" align="center">56.68</td> + <td class="dent" align="center">68.51</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">44.29</td> + <td class="br" align="center">46.75</td> + <td class="br" align="center">58.01</td> + <td class="dent" align="center">65.52</td></tr> +<tr><td class="br">Fort McKavitt</td> + <td class="br" align="center">46.74</td> + <td class="br" align="center">44.51</td> + <td class="br" align="center">53.66</td> + <td class="dent" align="center">67.05</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">44.75</td> + <td class="br" align="center">46.87</td> + <td class="br" align="center">57.39</td> + <td class="dent" align="center">66.25</td></tr> +<tr><td class="br">Fort Merrill</td> + <td class="br" align="center">54.51</td> + <td class="br" align="center">54.65</td> + <td class="br" align="center">61.82</td> + <td class="dent" align="center">74.50</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">54.82</td> + <td class="br" align="center">57.20</td> + <td class="br" align="center">68.66</td> + <td class="dent" align="center">73.27</td></tr> +<tr><td class="br">Fort Brown</td> + <td class="br" align="center">60.23</td> + <td class="br" align="center">61.60</td> + <td class="br" align="center">66.24</td> + <td class="dent" align="center">74.98</td></tr> +<tr><td class="br"><span style="margin-left: 3em;">Mean</span></td> + <td class="br" align="center">60.41</td> + <td class="br" align="center">63.63</td> + <td class="br" align="center">68.95</td> + <td class="dent" align="center">75.05</td></tr> +<tr><td class="br">Fort Inge</td> + <td class="br" align="center">52.21</td> + <td class="br" align="center">50.63</td> + <td class="br" align="center">61.22</td> + <td class="dent" align="center">74.48</td></tr> +<tr><td class="bbr"><span style="margin-left: 3em;">Mean</span></td> + <td class="bbr" align="center">49.46</td> + <td class="bbr" align="center">55.39</td> + <td class="bbr" align="center">62.63</td> + <td class="bb" align="center">68.02</td></tr></table> + +<p>The return transit to the south for this winter, 1855-6, has been an +extreme one. It is too early yet (Feb. 18th) to write its history, but the +extreme southern transit is as obvious as the unusual severity of the +cold. The rains which usually fall upon the Southern States<span class="pagenum"><a name="Page_414" id="Page_414">[Pg 414]</a></span> are +precipitated further south upon the West Indies, and threaten a +deterioration of their sugar crop. The snow, and cold winds, and ice, of +the middle latitudes, are felt even in Florida. Our sheet of +counter-trade has been exceedingly thin, and the barometer has ranged, in +fair weather, much below the mean. Occasional, and for a part of the time, +<i>weekly</i> periods of an increase of its volume, with a corresponding +elevation of the barometer, and a consequent moderation of the intense +cold, and a storm, have occurred. But those periods have been few and +brief. No regular thaw has yet occurred. From the 26th of December to this +date, at Norwalk, there have been but two periods when the wind has blown +from the south-west with sufficient force to stir the limbs of the trees. +There has been no wind from south of that point, or east of north-east; +and even our storm-winds, with one exception, have been north of +north-east—owing to the situation of the focus of precipitation far to +the south of us—and there is reason to fear that a cold summer like those +of 1816 and 1836 may follow. If this extreme transit is owing to defect in +the influence of the sun, from spots, or other causes, such will probably +be the result. If from volcanic action at the south, the influence of that +action may cease, and a rapid return transit, and an ordinary season, may +follow. Believing in the laws of periodicity in relation to the weather +and disease, I planted an early kind of corn (the Dutton), in 1836, and +had a crop when few around me succeeded. We must watch this return +transit, with hope, indeed, but not without fear, and be wise in time.</p> + +<p>There is a mass of other evidence in these summaries which shows the truth +of what I have written. There is not a deduction of Mr. Blodget which it +will not explain. The ascent of the summer lines of temperature to the +west is explained by the diminution of magnetic intensity. Their descent +in winter by the location and attractions of the concentrated trade. The +excess of precipitation in Alabama and Mississippi by the succession of +summer and winter belts. That of the interior of the Atlantic slope in +summer, by the showers which fall upon the elevations; and of the coast, +by the easterly storms and their attraction of the surface atmosphere of +the ocean, at other seasons. But I cannot further particularize. Even the +influence of the spots is clearly demonstrated by the observations at +<i>interior stations</i>, which were unaffected by contiguous oceans or +elevations. At Forts Washita, Gibson, Scott, Smith, and others, the years +1847 and 1848 were below the mean. All that evidence, and those +deductions, however, I must pass by for want of space, and take leave of +the subject.</p> + + +<p> </p><p> </p> +<hr style="width: 50%;" /> +<p><b>Footnotes:</b></p> + +<p><a name="f1" id="f1" href="#f1.1">[1]</a> See the diagram for summer at page <a href="#Page_55">55</a>.</p> + +<p><a name="f2" id="f2" href="#f2.1">[2]</a> Law of Storms, p. 42.</p> + +<p><a name="f3" id="f3" href="#f3.1">[3]</a> Kearakakua Bay (called Cavrico above), is on the S. W. side of the +island, and the trade was reversed during the day by the cloud +condensation inland.</p> + +<p><a name="f4" id="f4" href="#f4.1">[4]</a> Lieutenant Wilkes spent twenty days upon the top of this or an +adjoining mountain, and his observations there will be alluded to in +another connection.</p> + +<p><a name="f5" id="f5" href="#f5.1">[5]</a> All attempts to produce this result by the sudden exhaustion of air +about the chickens in receivers, or shooting them from cannons, have +failed, and no patent for a chicken-picker has been applied for.</p> + +<p><a name="f6" id="f6" href="#f6.1">[6]</a> A meter is 1 yard, and .0936 of a yard.</p> + +<p><a name="f7" id="f7" href="#f7.1">[7]</a> See his map, accompanying the Geography of the Sea.</p> + +<p><a name="f8" id="f8" href="#f8.1">[8]</a> See Am. Jour. of Science, New Series, Vol. 18. p. 187.</p> + +<p><a name="f9" id="f9" href="#f9.1">[9]</a> Their estimate was 100 to 120 miles.</p> + +<p><a name="f10" id="f10" href="#f10.1">[10]</a> Since the text was in type, and, as might have been anticipated, we +have intelligence confirmatory of this, from the Cape De Verde Islands. +The inter-tropical belt of rains has not moved as far north as the +northern islands—they have had no rain—and the people are in a starving +condition.</p> + + +<p> </p><p> </p> +<hr style="width: 50%;" /> +<p><b>Transcriber’s Notes:</b></p> + +<p>Punctuation has been corrected without note.</p> + +<p>Other than the corrections noted by hover information, inconsistencies in +spelling and hyphenation have been retained from the original.</p> + + + + + + + + +<pre> + + + + + +End of the Project Gutenberg EBook of The Philosophy of the Weather, by +Thomas Belden Butler + +*** END OF THIS PROJECT GUTENBERG EBOOK THE PHILOSOPHY OF THE WEATHER *** + +***** This file should be named 33429-h.htm or 33429-h.zip ***** +This and all associated files of various formats will be found in: + http://www.gutenberg.org/3/3/4/2/33429/ + +Produced by Robin Monks and the Online Distributed +Proofreading Team at http://www.pgdp.net (This book was +produced from scanned images of public domain material +from the Google Print project and from The Internet Archive: +American Libraries.) + + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. 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You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: The Philosophy of the Weather + And a Guide to Its Changes + +Author: Thomas Belden Butler + +Release Date: August 14, 2010 [EBook #33429] + +Language: English + +Character set encoding: ASCII + +*** START OF THIS PROJECT GUTENBERG EBOOK THE PHILOSOPHY OF THE WEATHER *** + + + + +Produced by Robin Monks and the Online Distributed +Proofreading Team at http://www.pgdp.net (This book was +produced from scanned images of public domain material +from the Google Print project and from The Internet Archive: +American Libraries.) + + + + + + + + + + THE PHILOSOPHY OF THE WEATHER. + AND A GUIDE TO ITS CHANGES. + + + BY T. B. BUTLER. + + + NEW YORK: + D. APPLETON & COMPANY, + NOS. 346 & 348 BROADWAY. + 1856. + + + + + Entered according to Act of Congress, in the year 1856, by + T. B. BUTLER, + In the Clerks Office of the District Court of the District of + Connecticut. + + + ELECTROTYPED BY + THOMAS B. SMITH, + 82 & 84 Beekman Street. + + + PRINTED BY + J. F. TROW, + 379 Broadway. + + + + +INTRODUCTION. + + +The atmospheric conditions and phenomena which constitute "The Weather" +are of surpassing interest. Now, we rejoice in the genial air and warm +rains of spring, which clothe the earth with verdure; in the alternating +heat and showers of summer, which insure the bountiful harvest; in the +milder, ripening sunshine of autumn; or the mantle of snow and the +invigorating air of a moderate winter's-day. Now, again, we suffer from +drenching rains and, devastating floods, or excessive and debilitating +heat and parching drought, or sudden and unseasonable frost, or extreme +cold. And now, death and destruction come upon us or our property, at any +season, in the gale, the hurricane, or the tornado; or a succession of +sudden or peculiar changes blight our expected crops, and plant in our +systems the seeds of epidemic disease and death. These, and other normal +conditions, and varied changes, and violent extremes, potent for good or +evil, are continually alternating above and around us. They affect our +health and personal comfort, and, through those with whom we are +connected, our social and domestic enjoyments. They influence our business +prosperity directly, or indirectly, through our near or remote dependence +upon others. They limit our pleasures and amusements--they control the +realities of to-day, and the anticipations of to-morrow. None can +prudently disregard them; few can withhold from them a constant attention. +Scientific men, and others, devote to them daily hours of careful +observation and registration. Devout Christians regard them as the +special agencies of an over-ruling Providence. The prudent, fear their +sudden, or silent and mysterious changes; the timid, their awful +manifestations of power; and they are, to each and all of us, ever present +objects of unfailing interest. + +This _interest_ finds constant expression in our intercourse with each +other. A recent English writer has said: "The germ of meteorology is, as +it were, innate in the mind of every Englishman--the weather is his first +thought after every salutation." In the qualified sense in which this was +probably intended, it is, doubtless, equally true of us. Indeed, it is +often not only a "first thought" _after_ a salutation, but a part of the +salutation itself--an offspring of the same friendly feeling, or a part of +the same habit, which dictates the salutation--an expression of sympathy +in a subject of common and absorbing interest--a sorrowing or rejoicing +with those who sorrow or rejoice in the frowns and smiles of an +ever-changing, ever-influential atmosphere. + +If consistent with our purpose, it would be exceedingly interesting to +trace the varied forms of expression in use among different classes and +callings, and see how indicative they are of character and employment. + +The sailor deals mainly with the winds of the hour, and to him all the +other phases of the weather are comparatively indifferent. He speaks of +airs, and breezes, and squalls, and gales, and hurricanes; or of such +appearances of the sky as prognosticate them. The citizens, whose lives +are a succession of _days_, deal in such adjectives as characterize the +weather of _the day_, according to their class, or temperament, or +business; and it is pleasant, or fine, or _very_ pleasant or fine; +beautiful, delightful, splendid, or glorious; or unpleasant, rainy, +stormy, dismal, dreadful or horrible. The farmer deals with the weather +of considerable periods; with forward or backward _seasons_, with "cold +snaps" or "hot spells," and "wet spells" or "dry spells." And there are +many intermediate varieties. The acute observer will find much in them to +instruct and amuse him, and will probably be surprised to find how much +they have to do with his "first impressions" of others. + +But I have a more important object in view. I propose to deal with "The +PHILOSOPHY _of the Weather_"--to examine the nature and operation of the +arrangements from which the phenomena result; to strip the subject, if +possible, of some of the complication and mystery in which traditionary +axioms and false theories continue to envelop it; to endeavor to grasp +_its principles_, and unfold them in a plain, concise, and systematic +manner, to the comprehension of "_the many_," who are equal partners with +the scientific in its practical, if not in its philosophic interest; and +to deduce a few general rules by which its changes may be understood, and, +ultimately, to a considerable extent, foreseen. + +This is not an easy, perhaps not a prudent undertaking. Nor is my position +exactly that of a volunteer. A few words seem necessary, therefore, by way +of apology and explanation. + +In the fall of 1853, in the evening of a fair autumnal day, I started for +Hartford, in the express train. Just above Meriden, an acquaintance +sitting beside me, who had been felicitating himself on the prospect of +fine weather for a journey to the north, called my attention to several +small patches of scud--clouds he called them--to the eastward of us, +between us and the full clear moon, which seemed to be enlarging and +traveling south--and asked what they meant. + +"Ah!" said I, "they are scud, forming over the central and northern +portions of Connecticut, induced and attracted by the influence of a +storm which is passing from the westward to the eastward, over the +northern parts of New England, and are traveling toward it in a southerly +surface wind, which we have run into. They seem to go south, because we +are running north faster than they. You see them at the eastward because +they are forming successively as the storm and its influence passes in +that direction, and are most readily seen in the range of the moon; but +when we reach Hartford you will see them in every direction, more numerous +and dense, running north to underlie that storm." + +I had seen such appearances too many times to be deceived. It was so. When +we arrived at Hartford they were visible in all directions, running to the +northward at the rate of twenty-five miles an hour. In the space of forty +minutes we had passed from a clear, calm atmosphere (and which still +remained so), into a cloudy, damp air, and brisk wind blowing in the same +direction we were traveling, and toward a heavy storm. My friend passed +on, and met the southern edge of the rain at Deerfield, and had a most +unpleasant journey during the forenoon of the next day. Taking the cars +soon afterwards, in the afternoon, for the south, I found him on his +return. + +"Shall I have fair weather now till I get home?" said he. + +"There are no indications of a storm here, or at present," I replied, "but +we may observe them elsewhere, and at nightfall." + +He kept a sharp look-out, and, as we neared New Haven, discovered faint +lines of cirrus cloud low down in the west, extending in parallel bars, +contracting into threads, up from the western horizon, in an E. N. E. +direction toward the zenith. + +"Now, what is that?" said he. + +"The eastern outlying edge of a N. E. storm, approaching from the W. S. W. +It is now raining from 150 to 200 miles to the westward of the eastern +extremity of those bars of cirrus-condensation; perhaps more, perhaps +less; and under those bars of condensation the wind is attracted, and is +blowing from the N. E. toward the body of the storm, and where the +condensation is sufficiently dense to drop rain. That dense portion will +reach here, and it will rain from twelve to fifteen hours hence. As we +pass along the shore, and run under that out-lying advance +cirrus-condensation, we shall see that the vessels in the Sound have the +wind from the N. E., freshening, but we shall continue to have this light +and scarcely-perceptible air from the northward for a time--_the N. E. +wind always setting in toward an approaching storm, out on the Sound, much +sooner than upon the land_." + +As we approached the storm, and the storm us, the evidence of denser +condensation at the west, and of wind from the east, blowing toward it, +became more apparent. The fore and aft vessels were running "up Sound" +with "sheet out and boom off," before a fresh N. E. breeze, and my friend +was astonished. + +"I must understand this," said he; "how is it?" + +"All very simple. The page of nature spread out above us is intelligible +to him who will attentively study it. The laws which produce the +impressions and changes upon that page, are few and comprehensible. +Although there is great variety, even upon the limited portion which is +bounded by our horizon, there is also substantial uniformity; and, +although the changes are always extensive, often covering an area of one +thousand miles or more, and our vision can not extend in any direction +more than from thirty to fifty, yet those changes are always, to a +considerable extent, intelligible, and may often be foreseen." + +"Has meteorology made such progress?" + +"By no means. It has, indeed, been raised to the dignity of a science, and +professorships endowed for its advancement. Some books have been written, +and many theories broached in relation to it; and innumerable observations +of the states of the barometer and thermometer, of the clouds, and the +quantity of fallen rain, and the direction and force of the wind--made and +recorded simultaneously in different countries--have been published and +compared; and a great many important facts established, and tables of +'_means_' constructed, and just inferences drawn, yet the _few and simple +arrangements_ upon which all the phenomena depend, and _their philosophy_, +have not yet been clearly elicited or understood." + +"Have not the 'American Association for the Advancement of Science' +arrived at some definite and sound conclusion upon the subject?" + +"No; it has been with them, for many years, an interesting subject for +papers and debate. Some very valuable articles, upon particular topics, or +branches of the subject, have been read and published. But the +_Cyclonologists_, as they term themselves, and who seem to think the great +question is, '_Are storms whirlwinds?_' appear with new editions and +phases of their favorite views as regularly as the annual meeting recurs; +and, though they have not convinced, they seem to have silenced their +opponents. The only conclusion, however, judging from their debates, to +which the Association appear to have come with any considerable unanimity, +is, that they are yet without sufficient _authentic observations_ and +well-established facts, to authorize the adoption of the Huttonian, +Daltonian, Gyratory, or Aspiratory, or any of the other numerous theories +which abound. And they are right. The subject is mystified by these +theories and speculations of the study, founded on barometrical and +thermometrical records, and the direction and force of the surface winds. + +"The qualities of heat were among the earlier discoveries of science, and +all the phenomena of the weather were forthwith attributed to its +influence. Hastily-formed and erroneous views of its power, and the manner +of its action in particular localities, and under particular +circumstances, have retained the credence accorded to them when first +announced, although subsequent discoveries have shown their fallacy; some +new theory of _modification_ having been invented to reconcile the +discrepancies as soon as they appeared. Perhaps it is not too much to say +(however it may seem to one not thoroughly acquainted with the subject, +who does not know that the _primary_ and secondary modifying hypotheses +found in Kaemtz, may be counted by hundreds) that there is not remaining in +any other science, and possibly in all others, an equal amount of false +and absurd theory, and of forced and unnatural grouping of admitted facts +to sustain it, as in meteorology as at present taught and received. +Astronomy, as a science, is almost perfected--the nature, and size, and +orbits, of the distant worlds around us are known--while constant changes +and alternating atmospheric conditions, which all occur _within less than +six miles of us_, affecting all our important interests, and obvious to +our senses, although much talked off, and made the objects of many +theories, are but little understood." + +"How, then, did you acquire the information you seem to possess?" + +"By studying '_the countenance of the sky_,' for in no other way has such +information ever been, or can it ever be, acquired. By a long-continued, +daily, and sometimes hourly observation of the clouds and currents of the +atmosphere, in connection with such reports of the then state of the +weather elsewhere, as have fallen under my notice, and the effect of its +changes upon the animal creation--for very much can be learned from them. +Yonder flock of black ducks that sit on that inshore rock, above the +tide--the wildest and most suspicious of all their tribe--although the +air is calm about them, know well that a storm is at hand. They probably +both see and feel it. As twilight approaches they will fly away inland, +forty or fifty miles perhaps, and settle among the lilies or grass which +surround some fresh-water pond, certain of remaining while the storm +lasts, and for one day at least, out of danger, and undisturbed. Many a +time, in my boyhood, have I heard, in the stillness of evening, the +whistling of their wings, as they swept up the Connecticut valley, to +seek, on the borders of the coves, and in the creeks of the meadows, a +concealed and safe feeding-place during a coming storm. And many a time in +the autumn, after they had all passed down for the season, when the +indications of an approaching storm were clearly visible at nightfall, +have I waited for them to return, on the eastern margin of a bend in the +cove, on the eastern side of a creek, to shoot them, though invisible, by +shooting across the head of the wake, which they made upon the water in +alighting, and from which the few remaining rays of twilight that came +from the western sky were reflected. + +"But I am far from being singular in this. That page is more extensively +read than is generally supposed. Many plain, unassuming men--farmers, +shipmasters, and others within the circle of my acquaintance--know more, +practically, of the weather than the most learned closet-theorist, or the +most indefatigable recorder of its changes. Every one, by studying the +page of nature above him, as he would the page of any other science, and +testing, by observation, the numerous theories invented to account for the +varied phenomena, may learn much, very much, that will be useful and +interesting to him, and which he can never learn from books, or +instruments, or theories alone." + +"Well," said my friend, "I am too far advanced in life, as are many +others, to commence such observations, and you must publish." + +I demurred, and he insisted. + +"It is difficult to spare the time; and I can not neglect my profession," +I urged. + +"Where there is a will there is a way," he replied. + +"It is difficult to make one's self understood without many +illustrations." + +"Very well, they are easily obtained." + +"But they cost money, and it is said 'science will not pay its way' like +fiction and humbug." + +"That," said he, "is a libel--such science will. Every one is interested +in the weather--all talk about it--and thousands would carefully observe +it, if they could be correctly guided in their observations." + +"I may get into unpleasant controversy." + +"Suppose you do; you can yield your position if wrong, and maintain it if +right, and _magna est veritas_." + +"But I may be mistaken in some of the views to which it will be necessary +to advert, if I attempt to systematize the subject." + +"Be it so--your mistakes may lead others to the discovery of the truth. +Besides, the weather is _common property_, and every one has a right to +theorize about it, or to talk about it, as they please--even to call a +stormy day a pleasant one, or make any other mistaken remark concerning +it; and every other person is entitled to a like latitude of reply. And +further," said he, with some emphasis, "no important observation, in +relation to a subject of such interest, should be lost; and, if you have +observed one new fact, or drawn one new and just inference from those +which have been observed by others; and especially if, from observation +and reading, you can deduce from the phenomena an intelligible, +_observable, general system_, it is not only your right, but duty, to make +it known. Such a knowledge of the true system is greatly desired by every +considerate man." + +To my friend's last argument I was compelled to yield. I could make no +reply consistent with the great principles of fraternity, which I shall +ever recognize. The promise was given. My friend went on his way, and I +went to the daguerreotypist to procure a copy of the then appearance of +the sky, as the first step toward its fulfillment. The fulfillment of that +promise, reader, you will find in the following work. It was commenced as +an article for a magazine, but it has grown on my hands to a volume. +Justice could not well be done to the subject in less space. It has been +written during occasional and distant intervals of relaxation from +professional avocations, or during convalescence from sickness, and it is, +for these reasons, somewhat imperfect in style and arrangement. But I have +no time to rewrite. There is much in it which will be old to those who +read journals of science, but new to those who do not. There is more which +will be new to all classes of readers, and may, perhaps, be deemed +heretical and revolutionary by conservative meteorologists; yet I feel +assured that the work is a step in the right direction--that it contains a +substantially accurate exposition of the Philosophy of the Weather, and +valuable suggestions for the practical observer. + +I have inserted my name in the title-page, contrary to my original +intention, and at the suggestion of others; for I have no scientific +reputation which will aid the publisher to sell a copy. Nor do I desire to +acquire such reputation. It can never form any part of my "capital in +life." Nor has it influenced me at all in preparing the work. I have aimed +to fulfill a promise, too hastily given, perhaps--to put on record the +observations I have made, and the inferences I have drawn from those of +others--to induce and assist further observations, and, if possible, of a +_general_ and _connected character_--and to impress those who may read +what I have written with the belief, that _they will derive a degree of +pleasure from a daily familiarity with, and intelligent understanding of, +the "countenance of the sky," not exceeded by that which any other science +can afford them_. + +I have examined, with entire freedom and fearlessness (but I trust in a +manner which will not be deemed censurable or in bad taste) the theories +and supposed erroneous views of others, for, in my judgment, the +advancement of the science requires it. Says Sir George Harvey, in his +able article on Meteorology, written for the Encyclopaedia Metropolitana: + + "It is humiliating to those who have been most occupied in + cultivating the science of meteorology, to see an agriculturist or a + waterman, who has neither instruments nor theory, foretell the future + changes of the weather many days before they happen, with a precision + which the philosopher, aided by all the resources of science, would + be unable to attain." + +The admissions contained in this paragraph, in relation to the comparative +uselessness of instruments and theories, and the value of practical +observation, are both in a good measure true. And the time has come, or +should speedily come, when "_pride of opinion_," and "_esprit du corps_," +among theorists and philosophers, should neither be indulged in, nor +respected; and when their theories should be freely discussed, and rigidly +tested by the observations of practical men. Such measure, therefore, as I +have meted, I invite in return. Let whatever I have advanced, that is new, +or adopted that is old, be _as_ rigidly tested, and _as_ freely discussed. +Let the errors, if there be any--and doubtless there are--be detected and +exposed. Let the TRUTH be sought by all; and meteorology, as a PRACTICAL +SCIENCE, advance to that full measure of perfection and usefulness, of +which it is unquestionably susceptible. + + + + +TABLE OF CONTENTS. + + + PAGE + + CHAPTER I. + + Heat and moisture are indispensable to the fertillity of the + earth--Arrangements exist for their diffusion and distribution, + and all the phenomena of the weather result from their + operation--Heat furnished or produced mainly by the direct + action of the sun's rays--Manner in which it is diffused over + the earth--Other causes operate besides the sun's rays--The + earth intensely heated in its interior--Heat derived from the + great Oceanic currents, and the aerial currents which flow + from the tropics to the poles, and from magnetism and + electricity--Water distributed by an atmospheric machinery as + extensive as the globe--Evidences of this--Its distribution over + the continents of North America--Explanation of it--Source from + whence our supply of water is derived, and from which our rivers + return 1 + + + CHAPTER II. + + Our rivers return in the form of clouds, and in storms and + showers--Definition and character of storms--Differences in + the character of the clouds which constitute them--Nomenclature + of Howard--Its imperfections--New order of description--Low + fog--High fog--Storm fog--Storm scud--N. W. scud--Cumulus-- + Stratus--Cirrus--Compounds of the two latter--recapitulation in + tabular form 24 + + + CHAPTER III. + + Our rivers do not return from the North Atlantic--All storms and + showers move from the westward to the eastward--Seeming clouds + seen moving from the eastward to the westward are scud--They are + incidents of the storm, and not a necessary part of it--The + storm clouds are above them, moving to the eastward--Occasions + when this may be seen--Admitted facts prove it--Investigations + prove it--May be known from analogy--From the fact that there is + an aerial current pursuing the same course in which the storms + originate--Character of this current--Its influence upon our + country--Importance of a knowledge of its origin, cause, and the + reciprocal action between it and the earth--To this end necessary + to go down "to the chambers of the South" 43 + + + CHAPTER IV. + + The trade wind region--Its extent and arrangements--Its belt of + daily rains and movable character--The trade winds--The extra + tropical belt of rains--Connection between them and their annual + movements--The counter-trades--Their origin and situation--One + of them constitutes our aerial current--It originates in the + South Atlantic as a surface-trade--Anomalies of the trade wind + region--Dry seasons--Humboldt's description of them--Exist where + the surface trades are situated--The rainless countries-- + Concentrated counter-trade--Monsoons--Received theory in relation + to them a fallacy--Cause of the great central phenomena-- + Calorific theory a fallacy--Land not hotter under the belt of + rains, nor sea materially so--Theory should be abandoned 52 + + + CHAPTER V. + + The agent, magnetism--Its character and currents--Oxygen + magnetic--Precipitation at the belt of rains occasioned by + depolarization--Storms originate in this central belt, and move + toward the poles 82 + + + CHAPTER VI. + + Course and functions of the counter-trade--Ours come from the + South Atlantic--Reason why it can not come from the Pacific-- + Mistake of Mr. Redfield and Lieutenant Maury in regard to it-- + All our storms originate in it--Proofs of this--State of the + weather, whether hot or cold affected by it--Proofs of this--All + our surface winds are incidents of it, and due to its conditions + and attractions--Proofs of this--Character of the different + winds--Anomalies of Mr. Blodgett accounted for--Received theory + in regard to sea and land breezes a mistaken one--Proofs of + this--Peculiar character of the N. W. wind--Identity with the + winter Mexican northers--Character of the West India hurricanes-- + Of the thunder-gust--Of the tornado--Sundry particulars in + relation to the latter--Due to currents of electricity-- + Proportions of winds in different localities--Examination of the + work of Professor Coffin upon that subject--Examination of + Lieutenant Maury's theory of the monsoons 92 + + + CHAPTER VII. + + Height of the counter-trade in different latitudes--Cause of the + Calms of Cancer--Influence of mountains upon the counter-trade-- + Reports of Herndon and Gibbon--Focus of precipitation in the + extra-tropical belt north of its southern line--Evidences of + this--The elevation of the counter-trade above the earth varies + in the same latitude with the variations in the phenomena of the + weather--Temperature of the counter-trade--Rain dust, its origin + and indications--Volcanic ashes--How far they indicate its course + of progression--Question whether there is an eastern progression + of the body of the atmosphere above the machinery of distribution 179 + + + CHAPTER VIII. + + Important to understand the precise character of the reciprocal + action between the earth and the counter-trade--Connection + between the width and movements of the belt of inter-tropical + rains and the volume of the trades--Its peculiarities over + Africa, the Atlantic, and South America--The magnetic equator-- + Character of the storms which originate in the inter-tropical + belt indicate local magnetic action--Supposed influence of + volcanic action--Gulf Stream changes its position--This the + result of magnetic action--Alternating contrasts of heat and + cold, and rain and drought--Dr. Webster's history of the + weather--Spots upon the sun--Their character and influence--Cold + or warm periods during the same decade, and during different + decades--Connection between the spots and magnetic disturbances + and variations--Influence of the moon upon the weather--No + decisive inference to be drawn from these facts, and a more + critical examination necessary 204 + + + CHAPTER IX. + + Examination of existing theories--Calorific theory the prevailing + one--Lateral overflow of Professor Dove--Absurdity of his views + in relation to them--His theory of hurricanes--Its absurdity--A + new theory by Mr. Dobson--Three theories advanced by + meteorologists of this country--Professor Espy's theory--Mr. + Bassnett's theory--Mr. Redfield's theory--Extended examination of + the latter--His theory in relation to the fall of the barometer + contradictory in its character--Philosophy of the barometric + change--No aid to be derived from these theories 232 + + + CHAPTER X. + + Further inquiry in relation to the reciprocal action between the + earth and the counter-trade--Terrestrial magnetism, and what we + know of it--Its elements, and their variations--Their connection + with the variations of atmospheric condition--Magnetism acts + through its connection with electricity--Character of the latter + and its variations--Their connection with atmospheric conditions-- + Electricity as well as magnetism in excess over this country-- + Effects of it upon our climate--Closer consideration of the + atmospheric phenomena--Their diurnal changes and connections + compared with those of magnetism and electricity--Grouping of all + the diurnal variations--Particular and separate examination of + them--Classification of storms--Examination in detail of the + several classes and the primary influence of the earth or + counter-trade in relation to each 285 + + + CHAPTER XI. + + Prognostics 340 + + + + +THE PHILOSOPHY OF THE WEATHER. + + + + +CHAPTER I. + + +Heat and moisture are indispensable to the fertility of the earth. Without +suitable arrangements for their diffusion and distribution, and within the +limits of certain minima and maxima, it would not have been habitable, or +the design of its Creator perfected. These arrangements therefore exist, +and "while the earth remaineth seed time and harvest shall not cease." Few +and simple in their character, though necessarily somewhat complicated and +irregular in their operation, the ultimate result is always attained. A +beautiful system of compensations supplies the losses of every apparent +irregularity in one section or crop, by the abundance of others. + +From the operation of these few, simple, connected, and intelligible +arrangements for the diffusion of heat and the distribution of moisture +over the earth, result all the phenomena which constitute the weather; and +by studying them, and their operation, we may acquire an accurate +knowledge of its "_Philosophy_." + +The necessary heat is furnished, or produced, mainly by the direct action +of the sun's rays; and the most obvious feature in the arrangements for +its diffusion is that by which the sun is made to shine successively and +alternately upon different portions of the earth. Nothing animate or +organic could endure his burning rays, if they shone continuously or +vertically upon one point, or could exist without their occasional +presence. Hence the provision for a diurnal rotation, to prevent the +exposure of any portion of the globe to the action of those rays for +twenty-four consecutive hours, except for a limited period, and at a +considerable angle, in the polar regions. But the earth is spheroidal, and +a diurnal revolution would still leave that portion which lies under the +equator too much, and the other too little, exposed to the action of the +sun. This is obviated by an annual revolution of the earth around the sun, +and an obliquity of its axis, by reason of which the northern and southern +portions are alternately and, as far as the tropics vertically, exposed to +the sun; and it is made to travel (so to speak) from tropic to tropic, +producing summer and winter, and other important phenomena. + +This obliquity and consequent change of exposure are in degree precisely +what the wants of the earth would seem to require. If it was greater, the +sun would travel further north and south, but the alternate winters would +be longer and more severe. If it was less, the end would not be as +perfectly attained. + +The direct action of the sun's rays upon the earth, particularly those +portions which lie north and south of the tropics, is not the only source +from which the supply of heat is derived. Although there is a general +increase of heat in spring and summer when the sun travels north, and of +cold when he travels south in winter, yet there are frequent +irregularities attending both. Very sudden and great changes occur in each +of them. Frost sometimes, cool weather often, occurs in midsummer, and +considerable heat and tornadoes in midwinter. And ordinarily the maxima +and minima of each month and, indeed, of each week are widely apart. Even +in the polar regions, in midwinter, _where the sun does not shine at all_, +the same moderating changes with which we are conversant occur in degree. +An extract or two from the register found in Dr. Kane's narrative of the +"Grinnell Expedition" will illustrate this. + + JANUARY 1851, (LATITUDE ABOUT 74 deg., LONGITUDE ABOUT 70 deg.). + + Date. Wind. Force. Ther. Bar. Sky and Weather. + + Jan. 3 calm -26.1 29.62 blue sky, m. + " 4 W. gent breeze -21.3 29.53 blue sky, + detached clouds, m. + " 5 W. by N. gent breeze -3.9 29.59 blue sky, m., + clouded over. + " 6 W. by S. light breeze -0.8 29.67 clouded over, m., + snow. + " 7 W. gent breeze -14.4 29.96 blue sky, detached + clouds, m. + " 8 W.S.W. light air -21.2 30.14 blue sky, m. + " 29 W.N.W. light air -18.9 30.19 blue sky. + " 30 NW. by W. light air -13.5 30.17 clouded over, m. + " 31 NW. by W. gent breeze -4.4 29.35 clouded over, snow. + Feb. 1 W. light breeze -11.7 29.27 cloudy, blue sky, m. + " 2 W. light air -25.1 29.62 blue sky, detached + clouds, m. + +These extracts are instructive. It will be seen that on the 3d of +January, when the sun had been absent some weeks, it was calm, the +thermometer stood at 26 deg. below zero (the - or minus mark before the +figures indicates that), and the barometer at 29.62, with blue sky, +somewhat misty or hazy--(the letter "m." standing for misty or hazy)--a +state of the air which existed most of the time when it did not snow or +rain, and therefore is of no importance in this connection. The next day +the thermometer began to rise, and the barometer to fall. On the 5th it +clouded over, and the thermometer rose rapidly, and on the 6th it had +risen more than 25 deg., and snow fell. On the 7th it cleared off, the +thermometer fell rapidly, and the barometer rose. On the 8th the +thermometer had fallen to 21 deg. below zero, and the barometer had risen to +30.14. Another instance, in all respects similar, occurred the latter part +of the month. We shall see hereafter that these changes are precisely like +those which occur with us, and every where. That, as in the polar regions, +and whether the sun be present or absent, or obscured by clouds, and by +night as well as by day, the changes from warm to cold and from cold to +warm are sudden and great, and that the latter are connected with the fall +of rain and snow--that every where in winter it _moderates to storm_. + +Many other instructive instances, especially in relation to the great +difference in the seasons in our own country, and upon the same parallels +elsewhere, might be cited if it were necessary. But they will more +appropriately appear in the sequel. + + +[Illustration: Fig. 1. + +In the above cut the isothermal lines are Centigrade. The zero of the +Centigrade thermometer is the freezing point of water, or 32 deg. of +Fahrenheit. The boiling point of water is 100 deg. Centigrade, or 212 deg. +Fahrenheit. A degree of Centigrade is equal to one degree and four-fifths, +Fahrenheit. The 0 deg. line of the cut, therefore, is 32 deg. of Fahrenheit--the +line of 5 deg. above is 41 deg. Fahrenheit--the line of 5 deg. below is 23 deg. +Fahrenheit, and so on. The reader, who is not familiar with the difference +in the scale of the thermometer, is desired to remember this; for we shall +make occasional extracts in which the temperature is given in the +Centigrade scale.] + + + +The cause of those irregularities, especially in the same seasons of +different years, and when very great, is often sought and supposed to be +found in the presence or absence of spots on the sun, ice floes and bergs +in the Atlantic, etc., etc. But neither the spots, nor ice, nor other +local causes produce them. The cause will be found in the character of the +arrangements we are considering, and the irregular action of the power +which controls them. + +Nor is the temperature of the northern hemisphere, north of the tropics, +equal in the same latitudes. Very great diversities exist in the "annual +mean" as well as the "mean" of the different seasons. Accurate +observations at many points have enabled men of science to demonstrate +this by drawing isothermal lines (_i. e._, lines of equal average annual +heat) from point to point around the earth, which show at a glance these +differences. The annexed cut is a polar projection of the isothermal lines +of the northern hemisphere, as far down as the tropic, copied from +Kaemtz's Meteorology. The dotted lines show the parallels of latitude, the +dark lines the isothermal lines, or lines of equal annual average +temperature. The reader is desired to observe how rarely they correspond +with the parallels of latitude, and how they fall below in a few +instances, and in others with great uniformity rise almost to the pole. + +Take, for example, the isothermal line of 0 or zero--that is, the line +where the mean or _average_ height of the thermometer _for the year_ is at +zero. At Behring's Straits this line is a little below the Arctic circle, +or the parallel of 66.30 north latitude. Passing east over North America, +it descends into Canada, almost to Lake Superior, and to about the 50th +parallel: that is to say, it is on an average during the year as cold on +our continent at the 50th parallel as it is near Behring's Straits at the +65th parallel. Passing east, the line of zero rises again over the +Atlantic Ocean until, in the meridian of Spitzbergen, it reaches, within +the Arctic circle, up almost to the 75th parallel. So, too, the isothermal +of 5 deg. below zero, which is below the 60th parallel in Siberia, rises in +the North Sea, above Behring's Straits, to the parallel of 75 deg., descending +on the continent in North America to the 55th parallel, and rising again +almost to the pole at Spitzbergen, to descend again in Siberia, while the +isothermals of 10 deg. and 15 deg. below zero, which in North America are but just +above the latitude of 60 deg. and 75 deg. respectively, ascend abruptly +_surrounding the magnetic pole_, and _falling short of the geographical +one_. Let this projection of the lines of equal temperature, and +particularly the situation of the magnetic poles, be studied well, for we +shall recur to it hereafter in illustration of many important portions of +our subject. + +It is apparent from these facts, and were it necessary might be rendered +still more so by referring to others, that other causes operate in the +distribution of heat over the earth besides the direct action of the sun's +rays upon it. Doubtless very considerable allowance is to be made for the +difference of seasons, and difference during the same season upon the +land and upon the ocean; in mountainous countries and level ones. But +making every allowance for them, the fact that other causes have a +_controlling_ influence in producing the deviations still remains most +obvious. Neither the difference of temperature between the land and the +ocean, or land surfaces of unequal elevations, will account for the +elevation of the isothermal lines on different portions of the ocean, or +their extension around the magnetic poles. + +Returning to a consideration of the arrangements for the diffusion of +heat, we observe: First, that the earth itself is intensely heated in its +interior. This is inferred, and justly, from the fact that the thermometer +is found to rise about one degree for every fifty-five feet of +descent--whether in boring artesian wells, exploring caves, or sinking +shafts in mines. It is demonstrated, also, by the existence of hot springs +and the action of volcanoes. Heat is supposed to be conducted from the +center toward the surface every where, but with difficulty and slowly. It +is also supposed to be conducted from the tropical regions toward the +poles. Such is the opinion of Humboldt. (Cosmos, vol. i. p. 167.) + +Probably it reaches the surface and exerts an influence, also, upon the +weather through the ocean, and by heating it in its greatest depths. +Little attention has been paid, so far as I am informed, to the question +how far the ocean is thus heated in _tropical latitudes_. Doubtless a +portion of the warmth of the ocean there is derived from that source, and +it has its influence in changing the temperature of the deep-seated cold +polar currents of, the great oceans. Perhaps it may yet be found that the +icebergs are detached by it in the polar seas--the observations of Dr. +Kane point to such a result. (Grinnell Expedition, p. 113, and also chap. +48.) + +Little need be said of the inconsiderable quantities of heat supposed to +be derived by radiation from the stars, the planets, and from space. If +any such are derived they are too inconsiderable to be of importance in +this inquiry. + +Heat is also carried, and in quantities which exert very considerable +influence upon the weather, from the tropics to the poles by the great +oceanic currents which flow unceasingly from one to the other. + +The most important of these with which we are acquainted is the Gulf +Stream of the Atlantic. Gathering in the South Atlantic, and passing north +through the Caribbean Sea and the Gulf of Mexico, it issues out through +the Bahama Channel, and flows north along the eastern coast of the United +States, but some distance from it, to Newfoundland, and from thence +continuing to the north-east and spreading out over the surface of the +ocean--a portion of it mingling with the waters of the North Atlantic in +passing--it flows up on the western coast of Europe, around the Faroe +Islands, and Spitzbergen, to the polar sea; passing around Greenland, and +perhaps through its Fiords, it descends again through the sounds and +channels of the Arctic regions into Baffin's Bay, and through Davis's +Straits, burdened with the icebergs and floes of the polar waters, to +return again to the South Atlantic. For reasons which will appear in the +sequel, it has comparatively little influence upon the weather of the +United States. Western Europe, however, Greenland, the islands which lie +in its course, and the polar seas, are most materially influenced. +Although not the only cause, it has very much to do with the remarkable +elevation of the isothermal lines over the Northern Atlantic, and upon +Western Europe, as seen upon the map. + +A like oceanic current exists in the Pacific Ocean, the influence of which +may also be traced upon the map by the elevation of the isothermal lines +at the northern extremity of that ocean, and upon the north-west coast of +North America. A vast amount of heat is transported from the tropical to +the temperate and frozen regions of the earth by these great oceanic +currents. + +Another supply is derived from aerial currents which flow from the tropics +toward the poles. These currents exist every where over the entire surface +of the earth, but in more concentrated volumes along the great "lines of +no variation," and greater magnetic intensity, on the western side of the +great oceans, over the eastern portions of the two continents of North +America and Asia. Not, as meteorological writers suppose, in the upper +portions of the atmosphere, having risen in the trade-wind region and run +off at the top toward the poles by force of gravity, but near, and +sometimes in contact with the earth. The influence of these aerial +currents upon the temperature of the atmosphere, and in producing the +phenomena we are to consider, is exceedingly important. We shall have +occasion to examine them with great care and minuteness under another +head, for upon them, more than any other portion of the arrangements, +depend not only the diffusion of heat, but also the distribution of +moisture. + +Still another supply of heat, during the sudden changes, at least, is +produced by the action of terrestrial magnetism and electricity. Very +great progress has been made within a short period, in the investigation +of the nature of these agents. The identity, or at least intimate +association or connection of heat, light, electricity, and magnetism, +always suspected, has been in various ways, and by a variety of +experiments demonstrated. The influence of magnetism if distinct from +gravitation, is second only to that; and its agency in producing the +phenomena we are considering is primary and controlling. We will only, in +this connection, ask the reader to note the situation of the north +magnetic poles (for there are two of them); the manner in which the +isothermal lines _surround_ them; the fact that they are _poles of cold_, +_i. e._, that it is colder there than even to the north of them. We shall +recur to this part of the subject again. + +Such, briefly considered, are the principal arrangements by which heat is +diffused over the earth. + +Equally marked by infinite wisdom, and equally interesting and important, +are the arrangements by which moisture is distributed. Doubtless the +general belief is that this is a simple process; that water evaporates +and rises till it meets a colder stratum of atmosphere, and then condenses +and falls again; or that, according to the Huttonian theory, currents of +air of different temperatures mingle and equalize their heat, and the +aggregate mass when equalized in temperature is cooler, and therefore is +unable to hold as much moisture in solution as the most heated portion +had, and the excess falls in rain. But the process is by no means so +simple, nor is heat the sole or most powerful agent concerned in it. +Currents of air do not mingle, but stratify. Evaporation from the surface +of any given portion of the earth outside of the tropics does not alone +supply that portion with rain. _Vast and wonderful, coextensive with the +globe itself, and perfectly connected, is the machinery by which that +supply is furnished even to the most inconsiderable portion of its +surface._ + +Take your map of North America and note, in this respect, its +peculiarities. It extends from the Isthmus of Darien to the Arctic +regions, and from the 65th to the 160th meridian of west longitude from +Greenwich, and has upon its surface a type of every climate in the world. +For the purpose of simplifying and illustrating the matter in hand, let us +divide it into five sections. Let the first section embrace Central +America and Southern Mexico, south of 28 deg.; the second, Northern Mexico and +Southern New Mexico, California, etc., between the parallels of 28 deg. and +32 deg.; the third, Northern California, Utah, Southern Oregon, and Western +New Mexico, north of the parallel of 32 deg.; the fourth, the entire +continent north of 42 deg.; and the fifth, the eastern United States, east of +the meridian of 100 deg.. These divisions are not intended to be entirely +accurate in their separation, but substantially so for the purpose of +illustrating the differences which exist in each. + +The accompanying diagram shows approximately, by dotted lines, the +divisions. + + +[Illustration: Fig. 2.] + + +Now let us see in what a diverse manner, and to what a different extent, +they are severally supplied with moisture. + +Central America and Southern Mexico lie within the tropics--their rains +are tropical rains. The season is divided into wet and dry, as are the +seasons of all tropical countries which are not rainless. During the rainy +season it rains a portion of nearly every day, and during the dry season +the sky is clear, the air is pure, and rain seldom falls. + +All around the earth within the tropics, over the land and over the sea, +there is a belt of almost daily rains, varying in width, north and south, +in different sections, but averaging about five hundred miles. This belt +of daily rains is formed at and by the meeting of N. E. and S. E. trades, +and travels north and south with them, as they do with the sun, +_encircling the globe_. By this narrow belt a portion of the earth's +surface, an average of some 35 deg. of latitude, is supplied with moisture. +Wherever it is situated at any given period, the tropical rainy season +exists; and when it is absent in its northern or southern transit, the dry +season prevails. Southern Mexico is within the range of this moving belt, +and in its course to the northward with the sun, in our summer from May to +October, it arrives over, and covers that country with a rainy season. +When the sun returns to the south, taking with it the trades and this belt +of tropical rains, that portion of Mexico is without rain, and dry, and so +continues until the rainy belt returns in the following year. While the +belt is over Southern Mexico it is nearly all _precipitation_, and there +is little _evaporation_; while that belt is _absent_ it is all +_evaporation_, with little or no _rain_. Surely this is not consistent +with the prevailing belief of simple evaporation, ascent to a colder +stratum, commingling, and condensation, and rain. Southern Mexico at least +is not supplied by mere evaporation from its surface, and must therefore +form an exception to that belief, and to the Huttonian theory. + +But we shall recur again to the peculiarity of distribution within the +tropics. + +Turn now for a brief space to Northern Mexico, Southern New Mexico, and +Southern California. In Northern Mexico, Southern New Mexico, Utah, and +California, between the parallels of 28 deg. and 32 deg., and particularly west of +the mountain ranges, we find an almost rainless region, sterile and +worthless, resembling that which is found upon nearly the same parallels +of north latitude in Northern Africa, Egypt, Arabia, Beloochistan, +Afghanistan, and North-western India; and in corresponding latitudes south +of the Equator, in Peru, a portion of Southern Africa, and the northern +and middle portions of New Holland. Why Northern Mexico and the other +countries named are thus sterile and comparatively rainless, we shall see +hereafter, when we examine critically the machinery of distribution as it +operates within the tropics. It is the fact that it is thus sterile and +rainless to which we desire to call attention in this place. + +Mr. Bartlett thus describes it: + + "On leaving the head waters of the Concho, nature assumes a new + aspect. Here shrubs and trees disappear, except the thorny chaparral + of the deserts; the water-courses all cease, nor does any stream + intervene until the Rio Grande is reached, three hundred and fifty + miles distant, except the muddy Pecos, which, rising in the Rocky + Mountains, near Santa Fe, crosses the great desert plain west of the + Llano Estacado, or Staked Plain. + + "From the Rio Grande to the waters of the Pacific, pursuing a + westerly course along the 32d parallel, near El Paso Del Norte, there + is no stream of a higher grade than a small creek. I know of none but + the San Pedro and the Santa Cruz--the latter but a rivulet, losing + itself in the sands near the Gila--the other but a diminutive stream, + scarcely reaching that river. At the head-waters of the Concho, + therefore, begins that great desert region, which, with no + interruption save a limited valley or bottom-land along the Rio + Grande, and lesser ones near the small courses mentioned, extends + over a district embracing sixteen degrees of longitude, or about a + thousand miles, and is wholly unfit for agriculture. It is a + desolate, barren waste, which can never be rendered useful for man or + beast, save for a public highway."--_Bartlett's Personal Narrative_, + vol. i. p. 138. + +Turning now to Central and Upper California, and Utah, and Southern +Oregon, we find still another peculiarity. Like Southern Mexico, they have +a rainy and dry season, but at a different period, and for a different +reason. The dry season of California, etc., is the summer of the northern +hemisphere, and her rainy season the winter. _California_ is, therefore, +_dry_ when Southern _Mexico_ is _wet_, and _vice versa_. The belt of rains +which supplies California with moisture during her rainy seasons is the +belt of _extra-tropical_ rains, which extends from the northern limit of +the north-east trades to the poles, encircling the earth. The southern +edge of this extra-tropical belt is _carried up_ on the western coast of +America, and in that portion of the continent in _summer_, when the sun +and trades, and the inter-tropical rainy belt travel to the north, and +uncover California, etc., leaving them without rain for a period of about +six months. + + +[Illustration: Fig. 3. IN SUMMER.] + + +As the sun, with the trades, travels south, the southern edge of the belt +of extra-tropical rain follows, and covers California, etc., again +extending gradually from the north to the south, and thus their wet +season returns. The annexed diagrams by the shading will show the +situation of the rainy belts which cover Mexico, Utah, New Mexico, and +California in summer and winter, and that the belts of rains are entirely +distinct and different in character. + + +[Illustration: Fig. 4. IN WINTER.] + + +Here again in this section of the continent, as in Mexico, evaporation is +going on for six months of the year, and were it not for the return of the +belt of rains from the north, in the fall, would go on for the entire year +without precipitation; and for the other six months precipitation is +vastly in excess. Nor can this be reconciled with, or explained by, the +Huttonian or any other received theory of rain. Here again it is obvious +that evaporation alone, however great or long continued, will not furnish +the evaporating section with rain. + +The northern portion of the continent lies beneath the zone of +extra-tropical rains, and north of the northern limit of the N. E. +trades--is never uncovered from it, and has no distinct rainy or dry +season, although more rain falls at certain periods, and in certain +localities, than at others. The climate of that part of Oregon which lies +upon the Pacific, and the character of its rains, resemble those of +North-western Europe, and will be further explained hereafter. + +Coming to the portion of the continent which we occupy, the 5th section, +we find it different still--a most favored region. Portions of it--Eastern +Texas, for instance--are upon the same parallels of latitude as the +rainless regions of Northern Mexico, etc. Eastern Texas, however, is not +rainless. Other portions are upon the same parallels as California, etc., +yet have no distinct rainy and dry season. We repeat, this section is a +most favored region--without a parallel upon any portion of the earth's +surface, except, in degree, in China and some other portions of Eastern +Asia. + +It is not only without a distinct rainy and dry season, but it is watered +by an average, annually, of more than forty inches of rain, while Europe, +although bounded on three sides by seas and oceans, and apparently much +more favorably situated, receives annually an average of only about +twenty-five--if we except Norway, and one or two other places, where the +fall is excessive. The distribution of this supply of moisture over the +United States is, in other respects, wonderful. Iowa, in the interior of +the continent, far away from the great oceans, on the east or west, or the +Gulf of Mexico on the south, receives fifty inches; some ten or fifteen +inches more than fall upon the slope east of the Alleghanies, and +contiguous to the great Atlantic (from which all our storms are, +erroneously, supposed to be derived), and the average over the entire +great interior valley is about forty-five inches, falling at all seasons +of the year. + +Observe, then, by way of recapitulation: Southern Mexico has a rainy +season furnished by the belt of _inter_-tropical rains, which _travels up +over it from the south_ in summer. California has a rainy season, which is +furnished by the _extra_-tropical belt of rains, which travels _down from +the north_, and covers it in winter. Northern Mexico and the adjoining +regions west of the 100th meridian are between the limits of the two, and +neither travels far enough to reach them, except for brief and uncertain +periods; they are comparatively rainless; while the eastern portion of +the continent, _in all latitudes_, unlike the others, is without a +distinctly marked dry season, or a rainless region, and with the exception +of occasional droughts, is abundantly supplied with rain at all seasons of +the year. + +And now, what is the explanation of all this? What produces the +extra-tropical belt of regular rains surrounding the earth, north of the +parallel of 30 deg. north, in some places, and 35 deg. in others, extending to the +pole, with its southern edge traveling up ten or more degrees in summer, +leaving large portions of the earth subject to a dry season; and back +again in the winter to give them a rainy one? What produces the narrow +belt of inter-tropical rains, encircling the earth; traveling up and down +every year over an average of 35 deg. of latitude, supplying every portion of +it alternately with rain? And what connects the two together over the +eastern portion of North America, so as to leave no distinctly marked wet +and dry season, and no rainless and sterile portion there? Are all these +the result of simple evaporation, ascent to a colder region, condensation, +and descent again? Demonstrably not. Of the forty inches which fall +annually upon the middle and eastern portions of the United States, an +average probably of one-half or twenty inches, runs off by the rivers to +the ocean, or is carried away eastward by the westerly and north-westerly +evaporating winds. The same is true, in degree, of the rain which falls +upon the other portions. Evaporation, therefore, could not keep up the +supply. From whence, then, does it come? this twenty inches, thus lost by +the rivers and winds, and with such wonderful regularity every year. + +"All the rivers run into the sea, yet the sea is not full. _Note the place +whence the rivers come, hither they return again._" + +But how is it that they thus return with such wonderful regularity, in a +narrow traveling belt of daily rains within the tropics, and a movable +belt of irregular rains without the tropics, extending to the poles, +leaving a space on each side of the equator encircling the earth in like +manner (except at two points, _viz._, Eastern Asia and Eastern North +America), from which they do not go, and to which they do not return, and +which is almost entirely unfurnished with rain? And all this without any +relation, whatever, to the contiguity of the oceans? Obviously this is not +the work of mere evaporation, or of the accidental or irregular +commingling of winds with different dew points, or quantities of moisture +in solution, or accidental, irregular changes of barometric pressure. _It +is one vast, wonderful, connected, and regular system--co-extensive with +the globe--necessary to the return of moisture from the oceans upon the +most inconsiderable portion of it, and to the condensation of the local +moisture of evaporation; and by it the waters are returned from the oceans +as regularly and bountifully upon the far interior of the great continents +in the same latitudes, as upon the "isles which rest in their bosoms."_ + + + + +CHAPTER II. + + +Before proceeding to an examination of this connected atmospheric +machinery, and an investigation of the particular ocean from which our +rivers return, it may be well to look at the form in which they appear to +return, that we may have a clear understanding of terms. + +They seem to return in the form of clouds, and in storms and showers, +although, in truth, they return in regular, uniform, ordinarily invisible +currents, and the storms and showers are but condensations in, and +discharges from portions of those currents, aided by the local moisture of +evaporation. + +The term _storms_, seems to be used by European meteorologists to denote +what we term thunder showers or gusts, and tornados; while what we call +storms are denominated by them regular rains. As the terms are extensively +in use in this country, we must adhere to the meaning attached to them +_here_ rather than _there_. + +Storms with us, then, are regular rains of from six to forty-eight or more +hours' continuance: generally without lightning, or thunder, or gusts, and +usually with wind of more or less force, from some easterly point. They +are called north-east storms, or south-east storms, according to the +point from which the surface winds blow. Practically we shall find that +this distinction is of some importance, for the north-east storms are the +longest, lasting generally twenty-four hours, or more, while the +south-east ones seldom, if ever, continue as long. + +These storms extend over a considerable surface, rarely less than one +hundred miles in one direction or another, and sometimes fifteen hundred, +or more. Distinct showers cover but a small surface, sometimes not more +than forty to one hundred rods, as in the tornado, and rarely more than +ten miles. Belts of showers, each new one forming a little more to the +south, often, in summer, pass across the country, following each other in +succession; and these belts may be of considerable width, say thirty to +one hundred and fifty miles. + +The clouds which constitute the storms and showers differ in appearance +and character, as well in the active as in the forming state. Clouds are +of distinct characters, alike, substantially, every where under like +circumstances; and a distinct nomenclature has been applied to them by Dr. +Howard, of London. He notes three kinds of primary clouds: _viz._, cirrus, +stratus, and cumulus; and inasmuch as the boundary line between them is +not very distinct, certain compounds of the three, _viz._: cirro-stratus, +cirro-cumulus, and cumulo-stratus. This nomenclature is every where +received, and portions of it are of great practical importance. + +The three principal descriptions of cloud, _viz._: the cirrus, the +stratus, and the cumulus, we have very much as they have in Europe, and +doubtless as they exist every where outside of the tropics. The nimbus, +another cloud described by him, is not distinct from the cumulus or +stratus. An isolated, limited thunder-shower in a clear sky, presents the +appearance of a nimbus, as shown in the cuts, but the basis of it is a +cumulus, and it differs from an ordinary fair-weather cumulus merely in +the dark and fringe-like appearance of the rain as it is falling from its +lower surface, and sometimes in the existence of a stratus above and in +connection with it. A similar form is often assumed by the peculiar clouds +of the N. W. winds in March or November, when they assume the form of +_squalls_, and drop flurries of snow. The nimbus, therefore, is not a +distinct cloud, but an appearance which the cumulus, stratus, or +cirro-stratus has in a stormy or showery state, and does not deserve a +distinct name. It is but a cumulus, or a stratus, or cirro-stratus +dissolving in snow or rain. It is important that this term should be +abandoned. It tends to confuse and prevent a clear understanding of the +difference in the character of the clouds, and in relation to which +precision is both difficult and desirable. + +The figures on pages 27 and 29, show the different kinds of clouds as +designated by Howard. They are copied from the engravings in the sixth +edition of Maury's "Sailing Directions." + + +[Illustration: Fig. 5.] + +[Illustration: Fig. 6.] + + + Figure 5. + The cirrus is indicated by 1 bird. + The cirro-cumulus by 2 " + The cirro-stratus by 3 " + The cumulo-stratus by 4 " + + Figure 6. + The cirrus by 1 " + The cumulus by 3 " + The stratus by 2 " + The nimbus by 4 " + +How far these representations correspond with the actual appearance of the +different compound forms in England, I can not say. But although they +convey a _general_ idea, _they are not sufficiently accurate for practical +illustration or observation here_. Indeed Howard himself has omitted from +his last edition his plate of the clouds, assigning as a reason, "that the +real student will acquire his knowledge in a more solid manner by the +observation of nature, without the aid of drawings, and that the _more +superficial are liable to be led into error by them_." The collection of +forms in the cuts _does not contain some very important ones_, and +contains some which are not distinct forms; but they may aid us somewhat +in this inquiry, and, therefore, I have copied them. It is well, also, for +the reader to have the generally received description before him. + +But for the purpose of _practical_ illustration hereafter, and greater +precision, I shall follow a somewhat different order in describing them, +and introduce two forms of _scud_ quite as important, practically, as any +other. + +First, then, commencing at the earth, we have what may be properly termed +_fog_, or low fog. This forms, in still clear weather, in the valleys, and +over the surface of the rivers and other bodies of water, during the +night, and most frequently the latter part of it, and is at its acme at +sunrise, or soon after, limiting vision horizontally and perpendicularly, +and dissolving away during the forenoon. It is rarely more than from two +to four hundred feet in height at its upper surface, and often much less, +and is composed of vesicular condensed vapor, sometimes sufficiently dense +to fall in mist, and is doubtless in composition substantially what the +clouds are in the other strata of the atmosphere, as observed by us, or +passed through by aeronauts. I have never seen it carried up to any +considerable height into the other strata by any of the supposed ascending +currents, to form permanent clouds, and shall have occasion to allude to +the fact in another connection. It disappears usually before mid-day, and +has, when thus formed, no connection with any clouds which furnish rain. + +To this Dr. Howard originally gave the name of stratus, and so it is +represented upon the cut; but the latter term may be with greater +propriety applied to the smooth uniform cloud in the superior strata from +which the rain or snow is known to fall, and I shall retain and so apply +it. + +The next in order, ascending, is high fog. This is usually from one to +two thousand feet in height at its lower surface. It forms, like low fog, +during the night and in still weather; and is rarely, if ever, connected +with clouds which furnish rain. It breaks away and disappears between ten +and twelve in the forenoon, usually passing off to the eastward. This fog +is most commonly seen in summer and autumn, particularly the latter, and +unless distinguished from cloud will deceive the weather-watcher. It is +readily distinguishable. Although often very dense, obscuring the light of +the sun as perfectly as the clouds of a north-east storm, it differs from +them. It forms in still clear weather, is present only in the morning, is +perfectly uniform, and, before its dissolution commences, without breaks, +or light and shade, or apparent motion, and unaccompanied by scud or +surface wind. The storm clouds are never entirely uniform, or without +spots of light and shade, by which their nature can be discerned, and +rarely, when as dense as high fog, without scud running under them and +surface winds. + +There is another fog still, connected with rain storms, but it does not +often precede them; occurring at all seasons, but most commonly in +connection with the warm S. E. thaws and rains of winter and spring; and +which usually comes on _after_ the rain has commenced and continued for +awhile, and the easterly wind has abated; occupying probably the entire +space from the earth to the inferior surface of the rain clouds or +stratus. Practically this does not require any further notice. It is an +_incident_ of the storm. When formed it remains while the storm clouds +remain, and passes off with them. It is sometimes exceedingly dense in +February and March, when it accompanies a thaw, and if there is a +considerable depth of snow, it has the credit of aiding essentially in its +dissolution. + +Mingled with the smoke of London, it produced there the memorable _dark +day_ of the 24th of February, 1832, and at various other times has +produced others of like character. (See Howard's Climate of London, vol. +iii. pp. 36, 207, 303.) These fogs have been so dense there that every +kind of locomotion was dangerous, even _with lanterns, at mid-day_. + +The next in order, ascending, are the storm scud, which float in the +north-east or easterly, south-east or southerly wind, before and during +storms. + +These, as the reader will hereafter see, are, _practically_, very +important forms of cloud condensation--although they have found no place +in any practical or scientific description given of the clouds, and are +not upon the cuts. They are patches of foggy seeming clouds of all sizes, +more or less connected together by thin portions of similar condensation, +often passing to the westward, south-westward, north-westward, or +northward with great rapidity. Their average height is about half a mile, +but they often run much lower. They are usually of an "ashy gray" color. +The annexed cut shows one phase of them, from among many taken by +daguerreotype. The arrows pointing to the west show the scud distinguished +from the smooth partially formed stratus above. This view was taken a few +hours prior to the setting in of a heavy S. E. rain storm. It is a +northerly view. + + +[Illustration: Fig. 7.] + + +At about the same height, but in a _different state of the atmosphere_, +float the peculiar fair-weather clouds of the N. W. wind. They usually +form in a clear sky, and pass with considerable rapidity to the S. E. +Sometimes they are quite large, approaching the cumulus in form, and +white, with dark under surfaces, and at others, in the month of November +particularly, are entirely dark, and assume the character of squalls and +drop flurries of snow; and then resemble the nimbus of Howard. They assume +at different times and in different seasons, different shapes like those +of the scud, the cumulus, or the stratus. + + +[Illustration: Fig. 8.] + + +They form and float in the peculiar N. W. current which is usually a +fair-weather wind, and are never connected with storms. In mild weather +they are usually white, and in cold weather sometimes very black, and at +all times differ _in color_ from the ashy gray scud of the storm. This +variety is not represented upon the general cuts. The annexed diagram +shows one phase of them, but they are readily observable at all seasons of +the year, when the N. W. wind is prevailing; differing in appearance +according to the season. Let these, as well as the storm scud, be +carefully observed and studied by the reader, and let no opportunity to +familiarize himself with their appearance be lost. A brief glance at +each recurrence of easterly or north-westerly wind will suffice. + + +[Illustration: SUMMER CUMULI.] + + +The _cumuli_ appear in isolated clouds of every size, or in vast clouds +composed of aggregated masses, as the peculiar cloud of the thunder +shower. They form as low down as the scud or fair-weather cloud of the N. +W. wind, which, for convenience, I will call N. W. _scud_; and often in +violent showers, and particularly in hail storms, extend up as far as the +density of the atmosphere will permit them to form. Professor Espy thinks +he has measured their tops at an altitude of ten miles. Others have +estimated their height, when most largely developed, at twelve miles; but +it is very doubtful whether the atmosphere can contain the moisture +necessary to form so dense a cloud at that elevation. It is their immense +height, however, whether it be six, or eight, or ten miles, together with +the sudden and violent electric action, condensing suddenly all the +moisture contained in the atmosphere within the space occupied by the +cloud, which produces such sudden and heavy falls of rain or hail. As the +rain drops or hail, when formed at such an elevation, in falling through +the partially condensed vapor of the cloud must necessarily enlarge by +accretion from the particles with which they come in contact, and probably +also by attraction, their size when they reach the earth, though +frequently very considerable, is not a matter of astonishment. The cumulus +is represented in the general plate with sufficient accuracy to show its +peculiar character. + +In summer, when the air is calm, the weather warm, and no storm is +approaching, there is always, in the day time, a tendency to the formation +of cumuli. This tendency exhibits itself about ten o'clock in the +forenoon, and they gradually form and enlarge until about two in the +afternoon; and after that, if they do not continue to enlarge and form +showers, they melt away and disappear before nightfall. Sometimes in July +and August the atmosphere will be studded with them at mid-day, floating +about three-quarters of a mile from the earth (in a level country), gently +and slowly away to the eastward. At times it may seem as if they must +coalesce and form showers, yet they frequently do not, but gradually melt +away, as before stated. + +The cumulus is the principal cloud of the tropics, and is not often seen +with us except in summer, or when our weather is tropical in character. + +The engraving on the preceding page, shows a phase of these fair-weather +summer cumuli. + +The last in order occupying (with their compounds) the higher portions of +the atmosphere, are the cirrus and stratus. The cirrus is often the +skeleton of the other, and precedes it in formation. + +These are the proper clouds of the storm, in our sense of the term. While, +however, the cirrus remains a cirrus, it furnishes no rain. When it +extends and expands, and its threads widen and coalesce into cirro-stratus +and stratus, or it induces a layer of stratus below it, the rain forms. + +The following is Dr. Howard's description of cirrus: "Parallel, flexuous +or diverging fibers, extensible by increase in any or in all directions. +Clouds in this modification appear to have the least density, the greatest +elevation, and the greatest variety of extent and direction. They are the +earliest appearance after serene weather. They are first indicated by a +few threads penciled, as it were, on the sky. These increase in length, +and new ones are in the mean time added to them. Often the first-formed +threads serve as stems to support numerous branches, which in their turn, +give rise to others." + +The illustrations in the general cut are imperfect, and do not represent +the delicate fibers of the cloud, for it is a difficult cloud to +daguerreotype or engrave, but the representation is sufficiently accurate +to give the reader a general idea of the different varieties, and enable +him to discover them readily by observation. They are the most elevated +forms, always of a light color, and often illuminated about sunset by the +rays of the sun shining upon their inferior surface; the sun, however, +often illuminates, in like manner, the dense forms of cirro-stratus, and +the latter, from their greater density, are susceptible of a brighter and +more vivid illumination. + +The stratus is a smooth, uniform cloud--the true rain cloud of the storm; +often forming without much cirrus above, or connected with it. It may be +seen in its partially formed state in the bank in the west, at nightfall, +or in the circle around the moon in the night. When it becomes +sufficiently condensed, rain always falls from it, but in moderation. If +there be large masses of scud running beneath it for its drops to fall +through (especially as is sometimes the case, in two or more currents), +the rain may be very heavy. But more of this hereafter. + + +[Illustration: Fig. 10.] + + +The annexed cut shows the forming stratus, light and thin, passing to the +east, as indicated by the short arrows just before a storm, while the scud +beneath is running to the west. + +It was copied from a daguerreotype view, facing northwardly. + +Intermediate between the fibrous, tufted, cirrus, and the smooth uniform +stratus, there is a variety of forms partaking more or less of the +character of one or the other, and termed _cirro-stratus_. No single +correct representation of cirro-stratus as a distinct cloud, can be +given--but several varieties will be hereafter alluded to, under the head +of prognostics. Several modifications are represented with tolerable +accuracy upon the cuts. + +The cirro-cumulus is a collection in patches of very small distinct heaps +of white clouds; they are called fleecy clouds, from their resemblance to +a collection of fleeces of wool, and are imperfectly represented on the +general cut. They do not appear often, and are usually _fair-weather +clouds_. + +This form has none of the characteristics of the cumulus, and does not +appear in the same stratum. It was probably called cumulus because its +small masses are distinct, as are those of the ordinary cumulus. It occurs +in the same stratum as cirro-stratus, and properly belongs to that +modification. I retain the name inasmuch as the cloud is of some practical +importance. + +The cumulo-stratus is seldom seen in our climate, as it is represented in +the cut. Stratus condensation _above_, and in connection with cumulus +condensation, is not uncommon, but that precise form is rare. + +This, too, is practically of no consequence, and I shall take no further +notice of it. + +Recapitulating, I give (in a tabular form) the three principal strata and +their modifications, located with sufficient accuracy for illustration. +The clouds which are found in an upper or lower portion of a stratum are +so represented by the location of their names; those which appear at all +heights in the stratum, with the names across. The elevation is the +average one--although there is no limit to the cirrus above, except the +absence of sufficient moisture. It was seen by Guy Lussac, and has been by +other aeronauts, at an elevation of five miles, or more, when too delicate +to be visible below. + + +------------------------------------------------+ + | | 3 miles. + |Cirrus. | + | Cirro-cumulus. | + | Cirro-stratus. | + | | + Primary | { Cumulus extending up | + stratum. | { in violent showers. | + | | + | | + |Stratus. | + |------------------------------------------------| + | | 1-1/2 miles. + Scud & |N. W. scud. { Cumulus Storm scud. | + cumulus |Fair-weather { ordinarily and | + stratum. | { its base always. | + | | + |------------------------------------------------| + | | 1/2 mile. + Fog |High fog. Storm fog. | + stratum. | | + | Low fog at the surface of the earth. | + | | + +------------------------------------------------+ + +With the assistance of this table of elevations, and a careful +observation, the reader can soon become familiar with the forms of clouds +and their relative situations. + + + + +CHAPTER III. + + +Having thus taken a brief view of the different clouds, let us return to +the inquiry, from what ocean, and by what machinery, _our_ "rivers +return." + +Not wholly or mainly from the North Atlantic, although it lies adjacent to +us, and they often _seem_ to do so; for, first, all storms, showers, and +clouds, which furnish, _independently_, any appreciable quantity of rain +to the United States, and even adjacent to the Atlantic, or indeed to the +Atlantic itself, come from a westerly point, and pass to the eastward. +_This is a general, uniform, and invariable law, although there is in +different places, and in the same place at different times, some variation +in their direction; ranging in storms from W. by S. to S. S. W., and in +showers between S. W. and N. W., to the opposite easterly points of the +compass; the most general direction, east of the Alleghanies, being from +W. S. W. to E. N. E._ + +But do we not see, you inquire--at least those of us who live east of the +Alleghanies--that when it rains, the wind is from the eastward; and that +the _clouds_ follow the wind from the east to the west? You do indeed, +generally, in all considerable storms, observe that the wind blows from +some easterly point, and that _seeming_ clouds are blown by it to the +westward; but what you see, and call clouds, are not the clouds which +furnish the rain. Far above the seeming clouds you notice, directly over +your head when it rains or snows, are the rain or snow clouds, dense and +dark, passing to the eastward, how strong soever the wind may blow from +the quarter to which they tend, or any other quarter, between you and +them. What you see below them are _scud_. So the sailors call them, and so +I have termed them. It is a "dictionary name," and a good one, expressive +of a distinction between them and _clouds_. They are thin, and the sun +shines through them, although with some difficulty, when the rain clouds +above are absent or broken. _This east wind and the scud are not the +storm, or essential parts of it._ Storms occasionally exist, particularly +in April, without either. They are but _incidents_, _useful_, but not +_necessary incidents_, as all surface winds are. + +If you could see a section of the storm, you would see the rain cloud +above, moving to the east, and the scud beneath running to the west, as +indicated by the arrows in the cut on page 40. Opportunities frequently +occur when these appearances may be seen. Storms are sometimes very long, +a thousand miles, perhaps, from W. S. W. to E. N. E., and not more than +one to three hundred miles wide from S. E. to N. W., and their sides, +particularly the northern ones, regular, and without extensive partial +condensation. Then the storm cloud above, moving to the eastward, and the +scud running under to the westward, may be seen as in the cut. + +So they may be seen before, at the commencement, and at the conclusion of +easterly storms, in a majority of cases, and the reader is desired to +notice them particularly as opportunities occur. + +The term _running_, too, is a very expressive one, used by sailors as +applicable to _scud_. For while the forming or formed storm clouds may be +moving moderately along, at the rate of twelve to fifteen or twenty miles +an hour, from about W. S. W. to E. N. E., the scud may be running under +them in a different direction--opposite, or diagonal, or both--at the rate +of twenty, fifty, sixty, and, in hurricanes, even ninety miles an hour. +You have doubtless seen these scud running from N. E. to S. W., and +without dropping any moisture, a day or sometimes two days, before the +storm coming from the S. W. reached the place where you were; and then, +sometimes the storm cloud slipped by to the southward, and the expected +storm at that point proved "a dry northeaster." Sometimes the +condensation, although sufficiently dense to influence and attract the +surface atmosphere, and create an easterly wind and scud, does not become +sufficiently dense to drop rain, and then, too, we have a dry northeaster, +which may melt away or increase to a storm after it has passed over us. _I +have never seen, except, perhaps, in a single instance, one of these +masses of scud, however dense, which had not a rain (stratus) cloud above +it, drop moisture enough to make the eaves run._ So you see it may be +true, and if you will examine carefully, you may satisfy yourself that it +is true, that the storms all move from a westerly point to the eastward, +notwithstanding the wind under them is blowing, and the scud under them +are running to the westward. + +There are many other methods by which the reader may determine this matter +himself. He may catch an opportunity for a view, when there is a break in +the stratus cloud above, and the sun or moon, no longer obscured by the +_storm cloud_, shines through the scud beneath. Then he may see they are +moving in different directions. _The upper cloud, if there be any of it +left, always to the eastward._ + +Again, we may see the storm approach from the westward, as it often does, +before the wind commences to blow, and the scud to run from the eastward; +particularly snow storms in winter, and the gentle showers and storms of +spring. + +Again, thunder storms, we know, come from the westward, and apparently +against an east wind. It is sometimes said they approach from the east, +but it is a mistake. During thirty years attentive observation in +different localities, I have never seen an instance. They sometimes _form_ +over us, or just east of us, or one may form at the east and another at +the west, and as they _spread out in forming_, one may seem to be coming +from the east, or there may be an easterly current, with dense flocculent +scud at the under surface of the shower cloud running westward, but they +finally pass off to the eastward, and never to the westward. It is +possible that a _patch of scud_ may become sufficiently _dense_ and +_electrified_ to make a _shower_, but I have never observed one. Such an +_apparent_ instance may be found recorded in "Sillman's Journal," vol. +xxxix. page 57. I have seen the scud assume a distinct cumulus form, but +never to become sufficiently dense to make a thunder shower. + +Thunder and lightning sometimes attend portions of regular storms in +spring and autumn, but the thunder is always heard first in the west, and +last in the east. + +Again, there are admitted facts with which you are conversant, which prove +this proposition. When it has been raining all day, and just at night the +storm has nearly all passed over to the eastward, and the sun shines under +the western edge of it, and "_sets clear_," as it is termed--you say that +"_it will be clear the next day_." Why? Because the storm will not pass to +the westward, covering the sun and continuing, how strong soever the wind +may be from the east; and because it is passing, and will continue to pass +off to the eastward, leaving the sky clear. _The easterly wind will stop +as soon as the storm clouds have passed, and it will fall calm, or the +wind will "come out" from the westward._ + +So, too, when the clouds are dark in the west in the morning, and the sun +rises clear, but "_goes into a cloud_," as it is expressed, you say that +it will rain. And if the clouds are dense this generally proves true; +because there is a storm or shower approaching from the west, and passing +over to the east, the western edge of whose advance condensation has met +the sun in his coming, and obscured him from your vision. + +When, too, it has been storming, and lights up in the N. W. you say it +will clear off; the N. W. wind will blow all the clouds away. It is, +indeed, generally true that when it so lights up it is about to clear off; +although it sometimes shuts down again, in consequence of the approach of +another storm from the westward, following closely behind the one which is +passing off. It is a great mistake, however, to suppose the N. W. wind +blows away the clouds. Watch the smooth stratus rain cloud at its lower +edge, where the clear sky is seen, and you will see that it is moving on +steadily to the N. E., in obedience to the laws of its current, and will +do so, even when its retreating edge has passed up to the zenith, and down +to the S. E. + +The storm uncovers us from the N. W. by the contraction of its width, _or_ +because it has a _southern lateral extension_ and _dissolution_, and not +by being blown away by the N. W. wind; although that wind, by its peculiar +fair-weather clouds, may be, perhaps, observed beneath, ready to follow +its retreating edge. + +Again, when it has been clear all day, and the sun sets in a bank of +cloud, you say--"_it will rain to-morrow, the sun did not set clear_," and +unless that bank is a thunder cloud, merely, which will pass over or by +you, with or without rain, before morning, it is generally true that it +will. The bank will prove the eastern edge of an approaching storm. + +From these generally admitted and understood facts, you may know that +storms pass from the west to the east. + +This proposition is also proved by all the investigations of storms, which +have taken place since the settlement of this country. Storms of great +severity attract particular attention, and are said to "back up" against +the wind, because they are observed to commence storming first at the +westward, although the wind is from the eastward. Doubtless you recollect +many such instances recorded in the newspapers. No season occurs without +such notices. + +Many storms have been investigated by Mr. Redfield, for the purpose of +sustaining his theory. Many others by Professor Espy, to sustain his. One +by Professor Loomis, with great research and ability--and some by others, +accounts of all which have been published; and every one yet investigated, +north of the parallel of 30 deg., has been shown to pass from a westerly to an +easterly point. + +So, too, we may know it from analogy. The laws of nature are uniform. +There is a great end to be accomplished, _viz._: the distribution of forty +inches of water, at regular intervals, over a large extent of country. The +rivers are to return, and the clouds are to drop fatness, and seed time +and harvest are not to cease. It is to be done and is done, by means of +storms and showers, and pursuant to general laws, as immutable as the +result. Most of these storms and showers, it has been found, and may be +observed, move from the westward to the eastward. Then we may know, from +analogy, that they do so in obedience to a general, uniform law; and so I +might say with confidence, if our inquiry stopped here, it will ever be +found by those who may hereafter examine them. + +But, 2d. There is a current in the atmosphere, all over the continent +north of the N. E. trades, but in great volume over the United States, +east of the meridian of 105 deg. W. from Greenwich--varying in different +seasons, and upon different parallels, and flowing near the earth, when no +surface wind interposes between them. In the vicinity of New York, the +usual course of this current is from about W. S. W. to E. N. E. In the +western and south-western portion of the United States, it is, doubtless, +more southerly--varying somewhat according to the season--and in other +sections varies in obedience to the general law of its origin, and +progress. + +I have observed its course in many places, between the parallels of 38 deg. +and 44 deg. N. _This current comes from the South Atlantic Ocean._ It is our +portion of the aerial current, which flows every where from the tropics +toward the poles, to which I have already alluded in connection with the +distribution of heat. _It brings to us the twenty inches of rain which we +lose by the rivers, and by the westerly winds, which carry off a portion +of the local moisture of evaporation, and its action precipitates the +remaining portion of that moisture. It spreads out over the face of our +country, with considerable, but not entire uniformity. All our great +storms originate in it, and all our showers originate in or are induced +and controlled by it._ + +_From the varied action, inherent or induced, of this current, most of our +meteorological phenomena, whether of wet or dry, or cold or warm weather, +result_; and a thorough knowledge of its origin, cause, and the reciprocal +action between it and the earth, is essential to a knowledge of the +"_Philosophy of the Weather_." + +Let us then go down to the "chambers of the south," to the inter-tropical +regions, of which we have said something in connection with a notice of +Southern Mexico, and see where, and how this great aerial current +originates. + + + + +CHAPTER IV. + + +Between the parallels of 35 deg. north latitude, and 35 deg. south +latitude--changing its location within this limit at different seasons of +the year--encircling the earth, and covering about one-half of its +area--we find the trade-wind region. In this region are the simple and +uniform arrangements, which extend every where, and produce all the +atmospheric phenomena. In the center of it we find that movable belt of +continual or daily rains, and comparative calms, particularly _near its +center_, about four hundred and fifty miles in width upon the Atlantic, +and over Africa, and the eastern portions of the Pacific, and something +more over South America and the West Indies, the western portion of the +Pacific and the Indian Ocean, to which we have already alluded. This belt +of rains and calms follows the trades and sun, in their transit north and +south, from one tropic to the other--its width and extension depending +upon the volume of trade-winds existing on the sides of it. Its southern +edge, when the sun is at the southern solstice, extends to 7 deg. south in the +Atlantic, to 10 deg. south in the Indian Ocean, and still further, probably, +over South America: on this point I do not pretend to be accurate, for +accuracy is not essential. When the sun is at the northern solstice the +southern edge is carried up as far as 12 deg. north, over the Atlantic, and +still further over the northern portions of South America, the West +Indies, and Mexico. It travels, therefore, from south to north, over from +twenty to forty degrees of latitude. The presence of this belt of rains +over any given portion of the inter-tropics, gives that portion its rainy +season, and its absence, as it moves to the north, or the south, gives the +portion from which it has moved, its dry season. It passes in its transit +twice each year over some portions of the country, Bogota, for instance, +and two corresponding rainy and dry seasons result. Its presence, and +character, and movements, are as fixed and regular, over from twenty-five +to forty degrees of the earth's surface, _and all around it_, as the +presence and movements of the sun over the same area. + +At the northern edge of this movable belt of rain, and extending in some +places, particularly in the Pacific Ocean, north about 20 deg., or about one +thousand four hundred miles, and in other places a less distance, the N. +E. trade winds prevail, blowing toward and into it from N. N. E., N. E., +and E. N. E., averaging about N. E. At the south line of this belt of +rains, extending south from twenty-five to thirty degrees, or from sixteen +hundred to two thousand miles, the S. E. trades blow toward and into it, +from the S. E., S. S. E., or E. S. E., averaging about S. E. Of course the +northern limit of the N. E. trades travels north and south with the belt +of rain, toward which it blows; and so the southern limit of the S. E. +trades travel in like manner with the rainy belt, or rather, to speak with +entire accuracy, the belt of rain moves with the trades, and the trades +follow the verticality of the sun. The following diagrams exhibit +approximately, and with sufficient accuracy for illustration, the +situations of the rainy belt and the trades, when at their northern and +southern limit, as well as the manner in which it must give certain +localities two rainy seasons each year, in its transit north and south. + +At the northern and southern limits of the trade-winds, and extending from +them to the poles, are found the variable winds and irregular +extra-tropical rains, all over the earth, which are shown by the shading +on the maps. This line of extra-tropical rains descends to the south, +following the retreating trades as they descend in our winter, and recedes +north before the trades when they return in spring and summer, so that at +the outer limit of the trades respectively, toward the poles, the line of +extra-tropical rains will be found, receding or following that limit, as +the trades pass up and down with the sun. From the north pole to the +northern limit of the N. E. trade-winds, wherever found, whether at 38 deg. +north latitude, as in some places in summer when the sun is at the tropic +of Cancer; or whether at 20 deg. to 30 deg. north latitude, as in our winter, when +the sun is at the tropic of Capricorn; the extra-tropical rains prevail. A +state of things precisely similar exists between the south pole and the +southern limit of the S. E. trades. Between this northern limit of the +N. E. trades and the northern line of the inter-tropical belt of +rains, wherever situated (with two exceptions, to which we have alluded +and shall allude again), there is, for the time being, a dry season; and a +like dry season between the southern line of the belt of rains and the +southern limit of the S. E. trades. We have, therefore, extending around +the earth, a belt of daily tropical rains, near the center,--two belts of +drought which are mainly trade-wind surfaces, one on each side of the +central rainy belt,--extending to the outward limits of the trades and the +line of extra-tropical rains; and these rainy and dry belts, moving up and +down after the sun, a distance of from twenty to forty degrees of +latitude, each year. + + +[Illustration: Fig. 10. IN SUMMER.] + +[Illustration: Fig. 11. IN WINTER.] + + +Such are the _main_ phenomena, _at the surface_, in the trade-wind region. +Ascending a step higher in the atmosphere, we find, above the +surface-trades, a counter-trade, running, not in the opposite direction, +but at right angles, or nearly so. The counter-trade which issues from the +northern side of the rainy belt, running to the N. W. or W. N. W., and the +counter trade which issues from the southern side, running to the S. W. or +W. S. W., varying, as the trades do in direction in different localities. +These counter-trades are continuations of the surface trades, which, +ascending in their course, have threaded their way through the opposite +trade in the rainy belt, and are continuing on at the same angle, and in +the same direction at which they blew upon the surface, and in obedience +to the same law. This is apparent from several considerations. + +1st. They issue at the same angle, and over the top of the surface trades. +In the West Indies and elsewhere, this has been ascertained and proved by +the course of the storms, and the rotation of their surface winds, and +observation. + +2d. We can not suppose the N. E. trade to be reflected, and turn back over +itself at a right angle. That would be impossible, even if there were a +wall of solid material there for it to blow against. Air is a peculiar +fluid, and it stratifies with astonishing ease. He who supposes that a +current of air put in motion can be turned aside by another current, or by +the atmosphere at rest, or can be made to mingle, is mistaken. It will +stratify, and force itself onward through the adjacent and opposing +atmosphere, and in a right line. I have observed some remarkable instances +of this character. + +3d. The cause which operates to produce the surface trades, still operates +upon the current to carry it over into the other hemisphere; a +counter-trade, as we shall see. It is impossible, therefore, to believe +that the surface-trades as they arrive at the belt of rains and calms, +turn at a right angle, or at any angle, and return: and impossible to +doubt that they pass through each other in this belt, and out at the +opposite side, as upper currents, at the same angle at which they entered. +Of course the N. E. trade of the Atlantic becomes the N. E. counter-trade +of South America, carrying their storms in a S. W. direction, and the S. +E. trade of the Atlantic the S. E. counter-trade of the West Indies, +carrying all their storms in a N. W. direction; and what is true of them +is true of the trade winds _every where, all over the globe, over the land +and over the sea_. + +Doubtless here some one will say, our upper current is a S. W. current. +True, the S. E. trade which enters the belt of rains, and issues out on +the north, a S. E. upper current or counter-trade, keeps that course until +it arrives at the northern limit of the surface trade, when, in _obedience +to another law_, which we shall notice, it gradually _decends near the +surface, curves to the eastward_, and becomes _the S. W. current which +passes over us_. And so we have the S. E. trade-wind of the South +Atlantic, with its moisture, warmth, electricity, and polarity, over, and +perhaps sometimes around us, dropping the electric rain which makes glad +our fields; giving us, when not prevented by other conditions, the balmy +air of spring, the Indian summer of autumn, and the mild mitigating +changes of winter; and thus, _our rivers, which run into the sea, return +to us again_. + +But let us go back to the trade-wind region--the region of regularity and +uniformity--and examine somewhat more attentively its features, that we +may more fully understand the character of this counter-trade. + +Here are 60 deg. at least of the 180 deg. of the earth's surface, and at its +largest diameter, covered in the course of the year, and of their travels, +by the trade-winds at the surface, the counter-trades above, and the belt +of rains and comparative calms, formed by the action of the opposite +trades, as they thread their way through each other, to assume the +relation of counter-trades. Truly the magnitude, simplicity, and +regularity of this machinery are most wonderful. + +There are, however, some _apparent_ anomalies which deserve attention. +Here are most distinctly marked the _rainy_ and _dry seasons_, existing +side by side. Here are the _rainless portions_ of the earth, already but +briefly alluded to; here the _monsoons_, and another peculiarity, _viz._: +the _gathering of the counter-trades_ upon the western sides of the two +great oceans, into two _aerial currents of greater volume_, _analogous_ +somewhat to the two _gulf streams_ of those oceans. Let us examine these +anomalies. + +The rainy and dry seasons depend, as we have seen, upon the transit north +and south of the rainy belt, or belt of comparative calms. Wherever this +belt may happen on any given day to be situated, each side of it the +trades prevail, it is dry, the earth is parched, and vegetation withers. +These changes are graphically described by Humboldt in his "Views of +Nature," as they occur on the northern portions of South America, as +follows: "When, beneath the vertical rays of the bright and cloudless sun +of the tropics, the parched sward crumbles into dust, then the indurated +soil cracks and bursts, as if rent asunder by some mighty earthquake. The +hot and dusty earth forms a cloudy vail, which shrouds the heavens from +view, and increases the stifling oppression of the atmosphere; while the +east wind (_i. e._ trade-wind), when it blows over the long heated soil, +instead of cooling, adds to the burning glow. + +"Gradually, too, the pools of water, which had been protected from +evaporation by the now seared foliage of the fan-palm, disappear. As in +the icy north animals become torpid from cold, so here the crocodile and +the boa-constrictor lie wrapped in unbroken sleep, deeply buried in the +dried soil. Every where the drought announces death, yet every where the +thirsty wanderer is deluded by the phantom of a moving, undulating, watery +surface, created by the deceptive play of the reflected rays of light (the +mirage). A narrow stratum separates the ground from the distant +palm-trees, which seem to hover aloft, owing to the contact of currents of +air having different degrees of heat, and therefore of density. Shrouded +in dark clouds of dust, and tortured by hunger and burning thirst, oxen +and horses scour the plain, the one belowing dismally, the other with +outstretched necks snuffing the wind, in the endeavor to detect, by the +moisture in the air, the vicinity of some pool of water not yet wholly +evaporated. + +"Even if the burning heat of day be succeeded by the cool freshness of the +night, here always of equal length, the wearied ox and horse enjoy no +repose. Huge bats now attack the animals during sleep, and vampyre-like +suck their blood; or, fastening on their backs, raise festering wounds, in +which mosquitos, hippobosces, and a host of other stinging insects, burrow +and nestle. Such is the miserable existence of these poor animals, when +the heat of the sun has absorbed the waters from the surface of the +earth. + +"When, after a long drought, the genial season of rain arrives, the scene +suddenly changes. The deep azure of the hitherto cloudless sky assumes a +lighter hue. Scarcely can the dark space in the constellation of the +Southern Cross be distinguished at night. The mild phosphorescence of the +Magellanic clouds fades away. Even the vertical stars of the +constellations Aquila and Ophiuchus, shine with a flickering and less +planetary light. Like some distant mountain, a single cloud is seen rising +perpendicularly on the southern horizon. Misty vapors collect and +gradually overspread the heavens, while distant thunder proclaims the +approach of the vivifying rain. Scarcely is the surface of the earth +moistened, before the teeming steppe becomes covered with Killingiae, with +the many-panicled Paspalum, and a variety of grasses. Excited by the power +of light, the herbaceous Mimosa unfolds its dormant, drooping leaves, +hailing, as it were, the rising sun in chorus with the matin song of the +birds, and the opening flowers of aquatics. Horses and oxen, buoyant with +life and enjoyment, roam over and crop the plains. The luxuriant grass +hides the beautiful and spotted jaguar, who, lurking in safe concealment, +and carefully measuring the extent of the leap, darts, like the Asiatic +tiger, with a cat-like bound on his passing prey." + +Such is Humboldt's description of the dry season on the Orinoco, and the +return of the belt of rains from the south. + +Again, within this trade-wind region are the _rainless countries_. These +are portions of the earth which the equatorial rainy belt does not ascend +far enough north in summer to cover, nor does the southern edge of the +extra-tropical regular rains descend, in winter, far enough south to cover +them, and where, of course, rain seldom, if ever, falls. Such are the +central parts of the Desert of Sahara, Egypt, Arabia, portions of +Affghanistan, Beloochistan, and the western parts of Hindoostan, to the +north of the inter-tropical belt, and a similar state of things exists +south of the equator in parts of South America, Africa, and New Holland, +although upon a comparatively small surface. + +Again, another anomaly is the gathering of the trade winds into greater +volumes, on the westerly side of the great oceans, and the consequent +carrying of the equatorial rainy belt up to the region of extra-tropical +rains, on the eastern side of the great continents of Asia and North +America, and the peculiar liability of these aerial gulfs to hurricanes +and typhoons. Such an aerial gulf gathers over the Caribbean Sea, and the +West Indies. Passing across the Gulf of Mexico, it enters over Texas, and +Louisiana, and the other southern states; its western edge passing north +in autumn and winter, on the eastern side of the highlands of Western +Texas, New Mexico, and the Great Desert; curving, as all counter-trades +do, to the eastward as soon as it passes the limit of the N. E. trades, +and spreading out over our favored country, leaving the evidence of its +pathway in the greater quantities of rain, which fall annually upon its +surface. This gathering deprives a portion of the Atlantic, north of the +tropics, of its share of the counter trade, and there, as every where, +where the volume of counter-trade is small, storms and gales are +infrequent, and of less force, and comparative calms prevail. That portion +of the Atlantic has long been known as "the horse latitudes," a name given +to it by our Yankee sailors, because, there, in former times, the +old-fashioned, low-decked, flat-bottomed, horse-carrying craft of New +England, bound for the West Indies, often floundered about in the calms +and baffling winds, until their animals perished for want of water, and +were thrown overboard. Lieutenant Maury, in his most praiseworthy and +exceedingly useful investigation of "The Winds and Currents of the Ocean," +has defined the situation of these calms and baffling winds at different +seasons--for they move up and down, of course, with the motion of the +whole machinery--and enabled navigators to avoid them, by running _east_ +before they attempt to make _southing_; and very materially shortened the +voyages to the equator. + +A like gathering, in volume, of the S. E. trade, on the western side of +the Pacific, enters over Asia, and covers China and Malaysia, extending, +in its western course, nearly as far as the western edge of Hindoostan. In +this concentrated volume of counter-trade, and owing to its concentrated +action, form and float the typhoons of the China Sea, and of the Bay of +Bengal; and to this anomalous aerial gulf stream, the S. E. portions of +Asia, from the western desert of Hindoostan, to the eastern portion of +China, north of the rainy belt, owe their great supply of moisture and +fertility, and their peculiar climate. The western line of this volume of +counter-trade is marked by the eastern portion of the rainless region of +Beloochistan, and the north-western deserts of India, as the western edge +of our concentrated volume of counter-trade, is marked by the arid plains +of northern Mexico, western Texas, and New Mexico. On the south of the +equatorial rainy belt, there is no corresponding aerial gulf of equal +volume, as there is no corresponding gulf stream of equal magnitude. On +the western side of the Indian Ocean we find a gathering of the N. E. +trades from the Bay of Bengal and the Indian Ocean, in which form and +travel the hurricanes which prevail--traveling to the southward and +westward--about the Isle of France or Mauritius; and the lagullus oceanic +current, which runs down to the S. W. toward the Cape of Good Hope. But +the extension of South America to the eastward, under, or just south of +the N. E. trades, does not permit the formation of such a concentrated +volume on the western side of the Atlantic, nor is the strength or +regularity of the N. E. trades, on that ocean, equal to those of the S. E. + +Nor is the magnetic intensity on the eastern and middle portions of the +Pacific, sufficient to produce such a concentration, in large volume, +there. The trades over that ocean, therefore, curve without concentration, +except a partial one, over the western groups of Polynesia, which the +Asiatic line of magnetic intensity approaches and where hurricanes are +sometimes found, until we arrive near the eastern line of magnetic +intensity, on the eastern side of Asia. We shall, hereafter, have occasion +to follow the anomalous concentrated volumes of the S. E. counter-trade, +of the northern tropic, on the western side of the great oceans, in +explanation of some of the phenomena which we find north of the trade-wind +region. Suffice it here to add, that if it were not for the concentration +of these counter-trades, on the western side of the great oceans, the +rainless region between the parallels of 20 deg. and 30 deg. would encircle the +earth; and China and the Eastern United States would have a distinctly +marked rainy and dry season, as have California, the Barbary States, +Syria, Persia, and other countries which lie north of the rainless region, +within the summer range of the N. E. trades, but also within the winter +descending range of the belt of extra-tropical rains. + +Another anomaly which we find in the trade-wind region, is the monsoon. +There are several of them, but they are found, in the greatest strength +and regularity, in the Indian Ocean. Another, defined by the +investigations of Maury, is found on the west coast of Africa, extending +out over the Atlantic. Another prevails on the western coast of South and +Central America. The etesian winds of the Mediterranean are but the N. E. +trades, whose northern limit is carried up in summer, by the transit of +the connected machinery, to the north, over that sea. The N. E. and S. E. +monsoons, so called, of the Indian Ocean, are but the regular trades, +blowing when the belt of rains is absent, as they do all over the globe. +The N. W. monsoon, south of the equator, in the vicinity of New Holland; +the S. W. monsoon which blows from the Arabian Sea, in upon Hindoostan; +the S. W. monsoon of the Atlantic, south of the Cape De Verde Islands; and +the variable west monsoon winds of the west coast of Southern and Central +America, and Southern Mexico (known under several different names, but +chiefly by that of Tapayaguas), are all that deserve attention as such. + +At first sight they appear to be anomalies, but the facts declare their +character with perfect certainty. First, they are not continuous, like the +trades, but _prevailing_ winds, and are _storm winds_; _they always blow +toward a region_, _or portion of the ocean_, _covered at the time by +clouds and falling weather_. + +Second, they do not blow upon, or toward, heated surfaces of land or +water--_i. e._, toward the dry and parched surfaces, where the dry season +prevails, or from adjoining cold waters on to warm surfaces, but toward +the land or water _situated under the rainy belt_. They are therefore +incident storm winds, (as our easterly winds are incident storm winds) of +the rain clouds of the tropics. They blow in upon the land, under the belt +of rains, while that belt with its daily cloud, and inducing electric +action, is over it, and follow that belt in its transit north and south. +They blow from the warm south polar current of the Atlantic, which flows +N. W. from the coast of Africa, toward the inshore north polar current, +which is there flowing south, but under the belt of rains. In the Indian +Ocean they blow from the center of that ocean, and the Arabian Sea, toward +the belt which hangs over Hindoostan, from the S. W.; and when the rainy +belt travels south they still blow toward, and under it, from the Indian +Ocean, but of course from the N. W. The heated character of the waters of +the Indian Ocean and Arabian Sea, which receive no polar currents, but +heated waters from the Persian Gulf, and from rivers which flow into the +Bay of Bengal over the heated plains of a tropical country, explain this. +So, too, the monsoon of the Atlantic Ocean, does not blow north of the +Cape De Verde Islands,--where the heated surface of Sahara, burning with +the rays of a vertical sun, has a temperature sometimes ranging from one +hundred and forty to one hundred and sixty degrees--but remains under the +rainy belt, drawn from the heated waters which flow up from the South +Atlantic, and travels north as the rainy belt travels north in summer, and +south to the Gulf of Guinea, as that travels south in winter. The same is +true of the Pacific monsoon, the Tapayaguas, the least marked of all, +which blows in during the rainy season upon the west coast of Southern +Mexico, and of Southern and Central America. They are all incident rain or +storm winds, blowing in upon the land, or on to a colder surface of +different polarity, _during the rainy season_; and if it were possible to +catch one of our north-easters, in its passage over our country to the +eastward, and anchor it to the Alleghanies, "paying out" so to have it +reach in part over the Atlantic, and keep it there in operation six +months, we should have a continual easterly wind under it; a _monsoon_ +more strongly marked than the monsoons of the Indian, or Atlantic Oceans. +_The received theory in relation to them is a fallacy._ + +Recapitulating, then, all the phenomena, we have,--_Surface-trades_, +blowing toward the center, passing through each other, and continuing on +as upper or counter-trades; a _belt of rains_, with calms near the center, +formed by the trades where they meet and pass through each other, which +travels with them north and south following the sun; _two belts of +drought_, following the belt of rains and the trades, and followed by the +_extra_-tropical line of rains, as it travels with the trades and the +rainy belt, leaving a part of the earth which the equatorial rainy belt +does not travel far enough north, nor the extra-tropical line of rains far +enough south to cover, and which is consequently a _rainless region_; _the +monsoons_, which are but incidents of the rainy belt, and the _gathered +volumes_ of counter-trade, on the west of the two great oceans, which +usurp the place of the N. E. trades, carrying the rainy belt up to the +region of extra-tropical rain, and preventing the rainless region from +encircling the earth. + +Upon _what cause_ do these great central phenomena, so vast, so regular, +so wonderful, depend? What is the _motive power_ of this connected +atmospheric machinery, whose action and influence extend over the entire +globe? + +"_Heat, heat_," say the text books, the Professors, the votaries of +meteorology. "All these phenomena are owing to the heat of the sun. It +heats the ocean and the earth--the air is thereby heated and rises, the +cold air rushes in from below, then the ascended current rolls off each +way at the top toward the pole, acquiring a westerly motion from the +rotation of the earth, slipping away from under it, and a different, +_viz._: an easterly motion, after reaching the latitude of 30 deg., from the +_same rotation_; and all the winds and disturbances of the atmosphere are +produced in the same way. They are produced by the action of heated +surfaces upon the adjacent atmosphere." + +This is the great theory of meteorologists, by which they attempt to +account for the various atmospherical disturbances, of both tropical and +extra-tropical regions. + +The whole theory is a fallacy--it will not stand the test of a careful +examination. The bases of the theory, which are assumed to be facts, are +not so. The agent has not the power claimed for it. A heated surface, +alone, never caused any considerable ascending current, or if it did, +never produced a mile of wind. I repeat it, the theory and all incidental +ones--the thousand explanatory and modifying theories, and +hypotheses--_the whole system_--is without foundation in fact, and will +not bear a critical examination. + +Let us see if this language is stronger than the facts will warrant. + +The theory assumes that both the land and water, under this central belt, +where the air is supposed to be rising are _materially hotter_ than the +land and ocean are on _either side of it_. Now, how much hotter are the +air and the land under the belt of rains and calms, upon Hindoostan, or +Africa, or South America, where the former is supposed to be acquiring +heat and expansion so rapidly, and to be ascending, than under, and in the +dry belts on either side? None; it is cooler by the thermometer--_much +cooler_. + +The central belt of rains in midsummer over Africa, extends up as far as +17 deg. north latitude, and perhaps further. North of this line over the whole +surface of the desert, the Barbary States, a part of the Mediterranean, +and some portion of Italy, the dry season extends, and from the entire +surface the N. E. trade blow into the central belt.[1] Over the desert +they all pass. Now this desert is a sea of sand, under a vertical sun, +intensely heated, blistering the skin with which it comes in contact, and +often acquiring a temperature of 150 deg. to 160 deg. of Fahrenheit. Under the +central belt of rains neither the earth nor air exceed the temperature of +84 deg.. And yet the hot air of the desert does not ascend, but blows into +this cooler central belt; and when it is felt as it blows off the western +coast by the mariner, or even in Guinea, when the belt of rains has gone +south in winter, as it often is as the _harmattan_, it is suffocating and +intolerable. There, then, not only is it untrue, that the land and the air +over it under the rainy belt are hotter, but it is true that intensely +heated air blows horizontally from the Desert of Sahara. Nay, as it will +appear in the sequel, this hottest of all surfaces not only can not have a +vortex, but it can not induce a monsoon, and scarcely a sea breeze. The +same is true in a great degree of the surface, and the air over it, on +either side of the supposed vortex of the rainy belt upon South America. +See the description of Humboldt, already given, where the thermometer +stood as high as 115 deg. of Fahrenheit in the shade, while the N. E. winds, +the regular trades, were blowing over the land. And it is equally true of +Arabia, and indeed of every portion of the earth. There is not a spot upon +the globe where the land and the air are cooler _by the side_ of the +central belt of rains, than _under it_. _And the opposite is true every +where upon the land._ + +How much hotter is the ocean and air under this supposed vortex? But +little hotter than they are on the side where the sun is not vertical, +_and none on the other_. Let us be a little more particular. The +temperature of the Atlantic under the belt of rains in our winter, and on +the south of the belt at the latitude of 3 deg. south, and down to 9 deg. or more +south, is 82 deg.. The air may range a degree, or possibly two, higher than +the water at either point. On the north this difference is from nothing at +the meeting of the trades and belt of rains, to about 4 deg. at their northern +limit. This is too _trifling_ to be worth one moment's consideration. It +is less, far less than the difference between the water and air of the +Gulf Stream which runs along our coast, and the adjoining waters and air +over them. While on the south side of the belt of rains the _difference is +actually against the theory_--and the same state of things is reversed in +summer, when the sun is vertical at the north. + +From the log of an intelligent shipmaster, found in the wind and current +charts of Lieutenant Maury, I abridge the following, which will illustrate +this. Captain Young in February, found the N. E. trades at about 17 deg. north +latitude, with the water at 75 deg. and air at 76 deg., trade-wind N. E. + + At 12 deg. 16' the water was 75 deg. the air 76 deg. wind N. E. + Feb. 22d. 9 deg. 49' " 76-1/2 deg. " 77 deg. " N. E. + " 23d. 7 deg. 13' " 78 deg. " 78 deg. " N. E. + " 24th. no obs. " 79-1/2 deg. " 79 deg. " N. E., + E. S. E. rain. + " 25th. 3 deg. 10' " 81 deg. " 83 deg. " E. S. E. rain. + " 26th. no obs. " 82 deg. " 82 deg. " S. E. to + E. S. E. hazy, + rain & sqs. + " 27th. 2 deg. 24' " 82 deg. " 82 deg. " calm, + with rain. + " 28th. no obs. " 82 deg. " 82 deg. " calm rain. + March 1st. 0 deg. 29' " 82 deg. " 82 deg. " E. S. E. + sqs. rain. + " 2d. 1 deg. 27' S. L. " 82 deg. " 82 deg. " S. E. sqs. + rain. + " 3d. 2 deg. 44' " 82 deg. " 83 deg. " S. E. & + S. S. E. + weather + settled. + " 4th. 4 deg. 17' " 82 deg. " 83 deg. " S. S. E. & + S. E. fair + weather. + " 5th. 6 deg. 08' " 82 deg. " 84 deg. " S. E. fair + wthr. + " 6th. 8 deg. 08' " 82 deg. " 84 deg. " S. E. & + E. S. E. fair + weather. + +Here the air was seven degrees colder at the extreme limit of the N. E. +trades than in the _center_ of the belt of rains, as it is, usually, in +mid-winter, but not in summer. On the other hand, _after he left the +region of calms and rains_, where the water and air stood with almost +entire uniformity at 82 deg., on the 3d of March, and for three days +thereafter, during which he was in the S. E. trades with fair weather, +the water was the same as under the supposed vortex, _viz._, 82 deg., _and the +air rose to 83 deg. and 84 deg._! _This is demonstration._ + +I also take from a letter of Lieutenant Walsh to Lieutenant Maury, +relative to the cruise of the "Taney" the following, showing the warmth of +the Gulf Stream compared with the adjacent ocean. + + "We first crossed the Gulf Stream on the 31st of October; we struck + it in latitude 37 deg. 22', longitude 71 deg. 26' as indicated by the + temperature of the water, which was as follows: + + 8 A.M. water at surface 66 deg. + 9 " " " 73 deg. + 10 " " " 76 deg. + 11 " " " 77 deg. + + 77 deg. was the highest temperature found in crossing at this time. + + Re-crossing it in May, in latitude 35 deg. 30', longitude 72 deg. 35', he + found the water as follows: + + 8 A.M. water at surface 71 deg. 8' + 9 " " " 73 deg. + 10 " " " 75 deg. 5' + 11 " " " 78 deg. 5' + 12 M. " " 78 deg. 5' + + 79 deg. being the highest temperature found." + +The average difference between the temperature of the water of the Gulf +Stream and the adjoining ocean, at the line of division, is about ten +degrees, increasing to more than twenty on approaching the coast, and +within one hundred miles--a far greater difference than is ever found on +the winter side of the inter-tropical rainy belt. + +It is not only not so, then, that the surface of the ocean is materially +warmer under the belt of rains than the adjoining surface under the +trades, especially on the summer side, but if it were so, the trades would +not be created thereby, any more than upon the Gulf Stream. And the +opposite is true of the land where the line of calms, and rains, and +drought meet, all around the globe. The fact assumed is therefore untrue. +The hottest surfaces, even at the rainless portion, where there is no +vortex, no storm, and no wind but the continual uniform N. E. horizontal +trade-wind, _never_ created, by reason of the heat alone, a mile of wind, +a storm or shower. + +But, again, the belt of calms, where the air is supposed to rise and +create a suction which draws the trades on either side a distance of from +one thousand to two thousand miles, an average of three thousand miles in +all, at least, is not itself, on an average, over five hundred miles in +breadth from north to south. What a wonder of meteorology is here! + +With a breadth of five hundred miles, the rising of the atmosphere is +supposed to be so rapid and of such immense volume that it draws the +surface atmosphere, one thousand to fifteen hundred miles on one side and +two thousand on the other, with a uniform steady velocity of twenty miles +per hour. Is this vast suction found by the unlucky mariner who may be +drawn within the vortex? _Not at all._ He finds no rapid suction there, +but _horizontal currents_, not steady, indeed, like the trades, and +sometimes calms _at the center_, but still the _currents are there_, and, +_except near the center, there as squalls, showers, and baffling winds +and as monsoons_. + +Again, is there at the mouth of this vortex, or as you approach it, an +increased rapidity in the trade corresponding to the magnitude of its +influence? Does the trade become a hurricane as it approaches the spot +where it is to supply the place of that which has suddenly "expanded by +heat, and been forced to rise, boil over, and run off at the top in turn?" +Not at all. It blows gently, even up to the very line of the rainy belt, +and becomes squally and baffling, falls gradually calm near the center, or +changes to a monsoon. + +But, again, the belt of rains is so far from being a belt of calms +strictly, that its monsoons in the Indian, Atlantic, and Pacific Oceans, +at times, extend hundreds of miles out over the ocean. That of the +Atlantic, triangular, with its base resting on Africa, according to +Lieutenant Maury, extends sometimes almost to the coast of South America, +a distance of one thousand miles, and thus under the supposed ascending +vortex. Where is the great uprising suction during the prevalence of this +extensive surface horizontal monsoon beneath it? Manifestly it does not +exist. Nay, that monsoon is blowing from the warm current which sets up +from the Cape of Good Hope toward the Caribbean Sea, and over the cold +north polar current, which runs down between the continent and the Cape de +Verdes. Equally untrue is the presumption that the air rises over heated +portions of the earth elsewhere, and by reason of such heating. +_Perpendicular currents of the atmosphere are rarely seen, never +extensive, or attaining any considerable altitude._ I have watched for +them thirty years. I have seen currents of air ascend, with their moisture +condensing as they ascended, and unite with the under surface of a highly +electrified cloud--the advance condensation of a thunder shower--but that +cloud was moving horizontally at a distance of from one to two thousand +feet above the surface of the earth, and did not rise. I have seen patches +of scud rising from the surface during the intervals of a showery and +highly electrified storm, toward, and uniting with, the clouds above, when +very low, as I have seen them approach and unite horizontally; and +doubtless there is a tendency upwards of the wind, created and attracted +by the summer shower, as may be seen in the ascending dust before the +rain, but I have never been able to detect an ascending current, except as +induced and attracted by a cloud above moving horizontally, in the hottest +day or dryest time. None of the clouds of our climate, even when the earth +is heated and parched by a two months' unbroken drought, can be detected +rising above the strata in which they form. I have watched the cumuli at +such periods when they filled the air, and can assert that they never +rise. The atmosphere moves, invariably, in horizontal strata, and the +whole theory of ascending currents is fallacious. + +But let us look still further at the tropical currents. The true harmattan +of north-western Africa (for the term is sometimes misapplied), hot and +blistering, generated upon the sand of the desert--why does it blow from +Sahara horizontally, on or over cooler surfaces, following the belt of +rains as a N. E. trade? Why does it not ascend? The sirocco of north +Sahara, the kamsin or chamsin of eastern Sahara, and the simoon of Arabia, +which blow hot and suffocating from those deserts--why do they blow _from_ +heated surfaces and _horizontally over_ cooler ones? Why do they not +ascend? Arabia is surrounded on three sides by seas and gulfs, from which +evaporation is rapid. Her interior deserts are extensive and intensely +hot--why are they rainless? Why do they not have a _vortex_, a _monsoon_, +or even a _shower_? Because there is no such law or action as this theory +supposes. Those winds blow horizontally in obedience to other laws, and +under the control of other and more powerful agents. But further still, +what heating and ascending process is it that makes the variable winds +north of the tropics? that brings in the warm air and fog of the Gulf +Stream upon our _snow-clad coast_, in mid-winter, to increase the January +thaw? Nay, what heating process is it that disturbs the calms of the polar +regions with fresh breezes and gales, sometimes of the force of 6, when +the _sun does not shine_, the thermometer is from 20 deg. to 40 deg. below zero, +the _earth and sea one frozen surface_, and the hardy explorer dressed in +furs, barely lives in his cabin covered by an embankment of snow, and +heated by a stove? + +Gentlemen, meteorologists, it will not do. The theory is unsound; the +assumed facts do not exist. The whole universe has not an agent, organic +or inorganic, which can play such absurd and inconsistent pranks in the +face of its Creator, as your various and complicated theories assign to +caloric. + +Away with the theory and all its incidental and complicated and mystified +hypotheses, they rest like a pall upon the science;--away with the whole +system, and let us seek some agent whose _power_ and _adaptation_ +correspond with the _extent_, and _simplicity_, and _magnificence_ of the +phenomena, and, in some degree, with the _power_ and _wisdom of their +Author_. + + + + +CHAPTER V. + + +One, and the principal end attained by the power of the agent, is the +gathering of a volume of atmosphere from, or near, the _surface_ of the +land and sea, so as to ensure its possession of all the moisture of +evaporation which rises from the locality, and the highest degree of +temperature, and from a space ranging from one to two thousand miles in +width, in one hemisphere, and to carry it over into the other. Not over +the top, or upon the top, of the whole mass of atmosphere situated in the +opposite hemisphere--_out of reach of all influences from the earth_--but +through it, and curving gradually down near to, and within influential +distance of the surface of the earth, soon after it passes the outward +limit of its fellow trade; and to continue the current onward, leaving +portions of it and its heat and moisture on the way, but taking a +considerable volume up and around the magnetic poles--it being impossible +for the entire volume to be thus carried around the poles in consequence +of the diminished circumference of the earth. To this end it is obvious it +must possess _polarity_. + +Another end to be attained is to combine the moisture of evaporation with +the air, so that the cold atmosphere through which, or the earth over +which it passes, may not be _continually condensing its moisture_, and +thereby _enveloping the earth in a perpetual mist_; but so that it may +part with it at _intervals_, making _cloudy_ and _clear days_; and part +with it in _portions_, so that a _regular_ and _necessary supply_ may be +furnished to the _entire hemisphere_, even up to the geographical poles. +Is there such an agent? There is, precisely and perfectly adapted to the +ends to be attained, ever there and ever active, and that agent is +_magnetism_. + + +[Illustration: Fig. 12.] + + +The earth is a magnet. It has its magnetic poles, and they are distinct +from its geographical ones; and there are two in each hemisphere. They are +situated from 17 deg. to 19 deg. distant from the geographical poles; and ours is +not far from longitude 97 deg. W. from Greenwich, and 71 deg. north latitude. +Navigators have gone north and north-west of it, and found its situation +by the declination of the needle. From these poles, lines of magnetic +intensity extend to the opposite and corresponding pole of the other +hemisphere, and upon or near those lines the needle points north without +variation; and toward these lines of no variation the needle every where, +on either side declines. The foregoing diagram shows the situation of our +magnetic pole and line of no variation, the dip of the needle by the +arrows, and the magnetic equator. + +Recent discoveries have shown that the magnetic force is exerted in lines +and currents; that such currents, as physical lines of force, surround +magnets, and currents of electricity. Doubtless such lines of force exist +around the earth and the magnetic poles. There are also _longitudinal_ +lines of force existing and active, between the poles, and extending from +one side of the center to the other, occupying nearly one third of the +magnet. If you take a large needle thoroughly magnetized, place it upon +paper and drop filings of iron upon it, they will become arranged about it +in circular and perpendicular, and also in _longitudinal lines_, +conforming to the currents. + + +[Illustration: Fig. 13.] + + +This experiment is illustrated in all our books on natural philosophy. + +The foregoing diagram, copied from Olmstead's Philosophy, does not show as +accurately as Faraday's projection of the lines upon a globe-magnet the +comparative distance from the poles of the needle, at which the +longitudinal currents commence and terminate, and _where the filings will +not adhere_ to any considerable extent. The lines shown upon the needle +should bear the same proportion to its length as the trade-winds bear to +that of the earth, measured from pole to pole, and if the needle had a +globular form they would so appear. + +These lines are made by currents arising from one side of the magnetic +equator, and passing over to the other. Doubtless, just such currents +rise, and pass over upon the earth. + +Magnetic and electric currents carry the air with them. This is well +settled by experiment. _Oxygen_, too, is _magnetic_, and capable both of +receiving and retaining polarity and of combining with, or attracting and +retaining vapor, and of course the moisture of evaporation. Here then we +have a power existing, capable of producing the result--precisely, and +with evident wisdom adapted to its production--ever present and active; +and no other known agent can. + +Is it not then the agent? + +Let us look a little further. This result is affected by the action of the +sun: the trades with the central belts of rains travel north and south +after it; so does the sun affect the magnetic currents every where, even +the magnetic needle is daily affected by its action, as it increases the +intensity of the terrestrial magnetic currents, and hence its well +established diurnal oscillations. + +Again, along the eastern lines of the continents which skirt the great +oceans on the west, run the northerly and southerly lines of no variation, +and of greatest magnetic intensity. Here are the trade currents gathered +into a volume, which curve and carry unusual fertility to South-eastern +Asia, and North America, and in those great aerial gulf streams we find +the _intense_ electric action which produces the typhoons of the former, +and the hurricanes of the latter. It may still be said that these +conditions and phenomena of the trade-wind region, are not produced by +magnetism or magneto-electricity, _but the objector can point to no other +adequate power_. That it must be heat, electricity, or magnetism, must be +admitted. There is no other power known. Heat demonstrably can not produce +them. Magnetism or electricity therefore must, and they are doubtless +states or phases of the same power, producing in their different states or +phases the different results. And even heat--atmospheric temperature, is +often, if not always the result of their action. In the present state of +science, it is enough for me that the _magnetic longitudinal currents are +there_; that they are _lines of force_ and _adequate_; that _oxygen is +magnetic_, and therefore the atmosphere must be affected by them--that so +far as we can reason from analogy, they ought to produce the effect upon +the atmosphere which we find produced, and until further light is thrown +upon the subject I shall presume that they do. Every step we take +hereafter in this investigation will confirm the presumption. + +There is one peculiarity to be more particularly noticed before we leave +the trade-wind region, and we are now prepared to notice it. + +The belt of rains, formed by the currents of the two trades, threading +their way through each other--how are they produced? Why should the place +where the currents thus pass through each other be a place of almost daily +precipitation? There is, in fact, no ascension, except that which the +currents have in their line of ascent to attain the elevation which the +magnetic law of the current requires. + +The trades have passed over an evaporating surface and are charged with +moisture. This moisture they hold in magneto-electric combination. +_Evaporation_ does not depend upon _temperature_. Ice and snow evaporate +at all temperatures (Howard, vol. 1, p. 86). So the cold N. W. wind, full +of positive electricity, will lap up, as it were, the pools from the +earth, with astonishing quickness; and when this electricity is deranging +the action of the machinery and material of the manufacturer, he allays it +by a supply of moisture, with which the electricity can combine. Nor does +the air lose its moisture when below the freezing point. In all parts of +the atmosphere, as at the surface of the earth in winter, moisture is held +in large quantities in the coldest and severest weather; and it is not +till it moderates, and a perceptible _electric_ change takes place, that +it is precipitated as rain or snow. Doubtless there is an exposure of +considerable surfaces, of opposite currents, charged with opposite +polarity, and a constant depolarization where their surfaces meet. May +there not be a consequent dissolution of the electro-magnetic combination +between the air and moisture, or the excitation of that electric action +which attends or produces like rains every where? and hence the constant +precipitation. This is rendered probable, by the fact that precipitation, +at the meeting of the trades, takes place in level countries in the +day-time, between 10 A. M. and sunset, in showers, with thunder and +lightning, as with us in summer, although among the mountains the rain +sometimes falls in the night also. The precipitation in the heat of the +day is obviously induced by the action of the sun, although it is by no +means certain that the friction of the opposing surfaces does not assist +in the operation. + +I am well aware that the lines of magnetic force curve upward and carry +the trades with them, and that, therefore, precipitation by condensation +from the mere cold of the upper stratum of the atmosphere is possible. +But, there are three reasons why I do not believe such to be the fact. + +1st. Precipitation takes place in the day time mainly, and in sudden, +isolated, heavy showers and not in steady continuous rain. Nor is there +condensation or continual mist at other hours of the day. + +2d. They occur at a time of day when the sun is affecting the magnetic +currents most powerfully, _viz._, between ten o'clock A. M. and sunset, +and mainly at the time of greatest heat. + +3d. The counter-trades _do not precipitate_ after they leave the rainy +belt, although at a great elevation, until they reach the outward limits +of the trades; and they _do precipitate again_, although they gradually +descend _nearer the earth_, as soon as they become subject to the action +of the currents of an opposite magnetism. Their precipitation is partial +too, even then, and they carry a portion of their moisture through an +atmosphere of the coldest temperature up to the geographical poles. + +A similar result attends the action of the sun in the extra-tropical +regions. Cumuli commence forming in the counter-trade, or at the line +between that and the surface current, at the same time of day that the +diurnal motion of the magnetic needle commences, or the rain clouds form +in the tropics; they continue to enlarge here as there, till about the +same hour of the day that the _needle_ obtains its maximum diurnal +variations; and when the influence of the sun upon the needle ceases, and +it returns to its original status, the cumuli disappear. Hail storms too, +it is said, always, or generally occur in the day time. + +In like manner the sea-breezes and other fair-weather surface winds, rise +in the forenoon with the influence of the sun upon the magnetic currents +and the needle, and die away at nightfall when the influence ceases. + +There are other electro-magnetic, or to speak more correctly, +magneto-electric, effects of the sun's action equally illustrative, which +tend to show that the precipitation at the passing of the trades, is the +result of their action upon each other, aided by the sun, to which we +shall allude when we come to speak of the causes and character of the +surface winds of the extra-tropical regions. + +As, however, this takes place only, or mainly, where the threading +surfaces meet, it is but partial, and the body of the respective polarized +currents pursue their way unaffected, toward the opposite magnetic +pole--and there for the present we leave them. + +Storms sometimes originate in these currents, when concentrated, as in the +West Indies, the China Sea, the Bay of Bengal, and Indian Ocean, while +passing through the rainy belt, and move with the current to the +north-west if issuing on the north side of it, and to the south-west if +issuing on the south side of it, until they respectively get beyond the +extreme limits of the trades, and then they curve to the eastward, +imbedded in and following their current. The peculiar extension of the +land to the east on the northern portions of South America, prevents the +gathering of an aerial gulf similar to the one which we have described to +the north-west, entering upon our division of the continent over the Gulf +of Mexico. It is otherwise in the Indian Ocean, and there the storms are +found issuing from the rainy belt on the southern side, sweeping over the +Mauritius and other islands of that ocean, and _often simultaneously_ with +storms issuing on the north over the Bay of Bengal. Colonel Reid mentions +instances and gives a diagram.[2] + +These storms in milder forms issue from the rain belt at other points, and +may issue any where, but will always be found most extensive and most +violent, that is to say, as hurricanes and typhoons, in the concentrated +volumes of counter-trade on the western side of the great oceans, within a +few hundred miles of the lines of magnetic intensity and no variation, and +when they form in the rainy belt they are highly electric. Most +frequently, however, as we shall see, they form in these currents after +they have issued from the rainy belt, and after they have passed the +extreme limits of the trades and become subject to the circular and +perpendicular magnetic currents which exist north and south of the +longitudinal ones, and which when seen upon the magnetic needle, attract +the filings and cause them to adhere--although but slight attraction or +adhesion takes place where the longitudinal currents exist. + +Such, then, are the atmospheric arrangements and phenomena of the +trade-wind region, and the cause that produces them; such is the character +and cause of the enlarged volume of counter-trade, which spreads out and +blows over our country as permanently as the S. E. trades blow on the +South Atlantic and South America, returning to us the rivers which had run +from us to the sea. + + + + +CHAPTER VI. + + +Coming back now, to a consideration of the course and functions of the +counter-trade after it leaves the northern limit of the surface-trades, we +find it curves to the eastward and gradually assumes about an E. N. E. +course, and becomes a W. S. W. current where it crosses the line of no +variation, and continues on until it passes off over the Atlantic; and +this course and curve is analogous to what may be found true of the +counter-trades every where. It is best illustrated by the course of all +the storms (in the American sense of the word, as distinguished from +thunder showers and other brief rains), which have been traced north or +south of the limits of the trades. It was found by Mr. Redfield in most of +the storms investigated by him, which originated within, or north of the +tropics. + +Doubtless it was the actual course of the others, and that the +investigation was imperfect. All the great autumnal, winter, or spring +storms which have traversed the whole or any considerable portion of the +territory of the United States, east of New Mexico, which have been +investigated by Professors Espy, Loomis, Redfield, or others, have been +found to follow this course. A storm which passed over Madeira, appears +from the investigations of Colonel Reid to have followed the same law of +curvature. + +And so, doubtless, did another which he has described as passing over the +Levant. The storms which supply the winter rains of California and Utah, +reach them by this law of curvature and progress, after the northern +limits of the trades have descended to the south with the sun, so that the +counter-trades of the Pacific may descend to the surface and curve in upon +them. But the absence of a concentration of the counter-trade, and its +deficient action because of its passage over mountain ranges, and their +location so near the northern limit of the trades that their storms can +not expand and become extensive, as well as their weaker magnetic +intensity, prevent their storms from becoming violent, and their supply of +rain is not large and much of it falls in showers. The same is true of the +Barbary States, of Syria, and Persia, and of Southern Europe; and indeed +of all the countries of the globe which lie between the winter and summer +extreme limits of the surface-trades, and without the limits of the two +concentrated counter-trades. Enough appears in the writings of the +meteorologists of Europe to show, that their long continued rains, which +are analogous to our storms and are _preceded by the formation of the true +cirrus of the counter-trade_, follow the same great law of curvature and +progress; although the presence of the Gulf Stream with its mass of south +polar waters on the western side of the British Islands, Denmark, and +Norway supplies them with showers, and fogs, and cumuli from the west and +north-west, and makes the mean of the surface winds of their storms +somewhat variant from ours. A like law reversed prevails in the southern +hemisphere. The storms of New Holland and the Indian Ocean, south of the +limits of the trade, curve to the eastward and travel about south-east, +their _south-west_ being a _clearing off wind_ as our _north-west_ is, and +_precisely similar in all its other characteristics_, where the relation +of magnetic intensity is the same. + +The storms of the Pacific on the S. W. coast of South America, in like +manner travel to the S. E., flooding the western slopes of the mountain +ranges with rain, and aggravated by the intensity of the magnetic currents +at the extremity of the continent in a high latitude, meet the mariner in +the face as he emerges from under the lee of the land and attempts to pass +the Horn. It will ultimately be shown that the precipitation which takes +place, as the storms and counter-trades pass north and east in the +northern hemisphere and south and east in the southern hemisphere, is +owing less to cold than increased magnetic intensity. And all this is the +result of one great uniform law, existing every where, varying in its +phenomena only in consequence of the difference in volume, and +magneto-electric intensity of the portions of the counter-trade, as of the +surface-trade at different places, and the different magnetic intensity of +the local perpendicular and circular currents of the earth over which they +pass, at different periods and at different points. + +Mr. Redfield and Lieutenant Maury have assumed that our S. W. current +comes from the Pacific Ocean. Aside from the adverse evidence which the +investigations of the former in relation to the course of the West Indian +storms, and their curving over the continent, furnish to the contrary, and +that which has herein before been stated in relation to the law of +curvature, it is obvious they are mistaken, for another and conclusive +reason. + +In order to reach us from the Pacific in a direction from S. W. to N. E., +it must pass the table lands and mountain ranges of Mexico and New Mexico, +and it would supply them bountifully, even if it did not thereby leave us +comparatively rainless and sterile. Every where currents passing from the +ocean _over mountain ranges_ part with a large share of their moisture. +Thus the counter-trade which curves over the Andes and over Peru, is +deprived of its moisture and leaves the western coast rainless. So in +degree of the counter-trade which curves over the Himalaya and Kuenlon +Mountains, and from there passes over the Desert of Cobi, to the north and +east--it is deprived by those elevated ranges of its moisture. So the +mountains on the south-western coast of South America are drenched with +rain, while Patagonia, which lies on the east of them is comparatively +dry. And so of every other country similarly situated. + +Now the mountain ranges and table lands of Mexico are not thus supplied +with moisture. For the space of four months in Southern and less in +Northern Mexico, and in summer, and while the belt of the tropics is +extended up over them, they have rain and in daily showers which _travel +up from the south_, indicating the course of the counter-trade. (See +Bartlett's Personal Narrative, vol. ii. p. 286.) At other seasons, and +while we are bountifully supplied, they are dry. In short, there are no +two portions of the earth that differ more widely in regard to their +supply of moisture, and all their climatic characteristics and relations. +It is therefore, according to all analogy, impossible that our +counter-trade should come from the South Pacific across the continent and +below 35 deg., and in this also those gentlemen are mistaken. + +Messrs. Espy and Redfield recognizing the existence of "a prevailing" S. +W. current, but considering the surface-winds beneath it as the principal +actors in producing the atmospherical conditions and changes, have +attributed no office to that current, except that of giving direction and +progression to our storms. This is their great mistake. It plays no such +unimportant part in the philosophy of the weather, as we have already +incidentally seen, and will proceed still further to consider. + +_All our storms originate in it._ This we may know from analogy. + +_Where there is no counter-trade, outside of the equatorial belt of rains, +and within influential distance of the earth, there are neither storms nor +rain._ So, when, as we have seen, the concentration of the volume of +northern counter-trade in the West Indies, gathered by the hauling of the +S. E. trades more from the east, as they approach the central belt, +diminishing the volume of the counter-trade over the North Atlantic, the +calms and drought of the horse-latitudes are found. And when the +counter-trade is small in volume and weak in intensity, by reason of the +fact that the surface-trades from the opposite hemisphere which constitute +it, formed upon land where evaporation was small, as upon Southern Africa +and New Holland, or formed where the magnetic intensity was weak, or +passed over mountain ranges in their course, the annual supply of rain, +the ranges of the barometer, and the alternations of atmospheres +conditions are remarkably less. + +We have already seen where the rainless portions of the earth are, and why +they are so; because those lying north of the northern limit of the +equatorial rainy belt were yet too far south to be covered by the line of +extra-tropical rains; or in other words, too far south to be uncovered by +the surface N. E. trades and the longitudinal magnetic currents, and to be +covered by the counter-trades in contact, or nearly so with the earth, and +influenced by the perpendicular north polar magnetic currents. Thus we +have seen that the rains of Southern Mexico were summer rains, due to the +northern extension of the equatorial rainy belt; those of California were +winter rains, due to the southern extension of the extra-tropical rains +following the N. E. surface trades. We have also briefly alluded to the +fact that either side of the equatorial rainy belt, evaporation is going +on for months under a vertical sun, without precipitation--unless it be +from an occasional brief storm of great intensity which originates in that +belt at the line of it, and passing on in the counter-trade, reverses, for +the time being, by its concentrated and powerful action, like a magnetic +body introduced into the field of another magnet, the surface-trades. Mere +evaporation then, does not produce the storm, or shower, or rain, where +most active in the dry torrid zone. It may be said that those dry portions +are, for the time being (as the rainless portions of the earth are +continually), within the operation of the surface-trades, and that +therefore the evaporated moisture is carried away by them toward the +equatorial rainy belt. Precisely so; but why carried away? Why should it +not condense, occasionally, at least, and drop the rain as it passes +along, if a great supply of moisture from excessive evaporation could +furnish rain. Perhaps it may still be said it is going from a cold to a +warm section. This is not true, as we have shown. + +But, it may be said that the rainless regions at any rate receive no +moisture, and therefore can not supply any by evaporation. This would not +meet the case, as it would still be true that when the rainy belt has left +a given spot, the dry weather sets in with excessive evaporation, and the +north-east trades in summer, blowing from the countries lying north of the +rainless regions, and which have been supplied during the interval by the +extra-tropical rains, and are loaded with evaporation, are passing over +the rainless regions on their way to enter the central belt. So blow the +N. E. trades from the Mediterranean, and the Barbary States _over the +Desert of Sahara_ and into the rainy belt south of it; but drop no +moisture on their way, because exposed to no magnetic currents of an +opposite polarity. + +But it is not true that all the rainless regions are without evaporation. +Egypt is an exception. The annual freshets of the Nile saturate its +central valley, and vast reservoirs of water are saved from it and let out +over its surface, and it all evaporates, but produces no rain. And so are +large quantities turned aside and scattered over the bottom lands of +Northern Mexico, and other countries, during the dry season, and their +evaporation furnishes no rain. Hygrometers and dew points are of no +consequence there--nor are they of any, on either side of the rainy belt, +where six perpendicular feet of moisture is evaporated in six months. + +Again we have alluded to a strip of coast on the Pacific west of the +mountain ranges of South America, lying partly in Peru, partly in Bolivia, +and partly in Northern Chili, which, although long and narrow, washed by +the broad Pacific Ocean, is without rain. South America has no other +_wholly_ rainless region, so far as is known. A part of this region would +lie between the equatorial belt of rain, and the southern extra-tropical +one, and never be covered by either; but the volume of N. E. trades from +the Atlantic, although from the make of the land not concentrated to so +great an extent as the volume of S. E. trade on the north, and therefore +not so liable to hurricanes and other violent storms, is yet sufficiently +so to carry the southern line of the equinoctial rainy belt down in winter +to the summer line of extra-tropical rains, and give a supply of rain to +all the continent--leaving no strictly rainless region south of the +equatorial rainy belt and east of the Andes. Those mountains, however, +present a barrier to its south-western progress which it doubtless passes +to some extent, but deprived of its moisture, and unable to supply the +rainless coast region of Peru, Bolivia, and Northern Chili. There is, +therefore, a portion of this rainless line of coast which is within the +region of extra-tropical rains, over which a portion of the N. E. trades +of the Atlantic, as a counter-trade, should or do, curve, and where there +should therefore be extra-tropical rains. It is washed by the Pacific, an +evaporating surface, and westerly and south-west breezes are drawn in from +that ocean over it. Why then is it rainless? The only reason which can be +assigned why rain does not fall there is that the high mountain ranges of +the Andes intercept and perhaps in part divert the counter-trade, and +deprive that portion of it which passes them, of its moisture, by that +reciprocal action of opposite polarities which takes place whenever and +wherever the trade approaches so near the earth; and it curves over the +narrow line of coast with the feeble condensation, and imperfect forms, +and varied coloring which mark so peculiarly the rainless clouds of that +region. (See Stewart's Journal of a Voyage to the Sandwich Islands, page +72.) + +Again, it is estimated, and on reliable data, that twelve perpendicular +feet of water are annually evaporated from the surface of the Red Sea, +between Nubia on one side, and Arabia on the other; yet they are both +rainless countries, except so far as the inter-tropical belt of rains +extends up on to a small portion of them. The moisture of evaporation, +floated up from a surface covered by the surface-trade is invariably so +combined as to remain uncondensed till it has passed south into the +equatorial rainy belt, and over to the opposite hemisphere, and been +exposed to the currents of an opposite magnetism. + +Again, the N. E. trades extended up in summer over the Mediterranean Sea, +an evaporating surface, blow over the Barbary States in June and July, but +furnish no rain. And so of the S. E. or N. E. trades which blow over +Brazil and other countries in the absence north or south of the tropical +belt of rains. + +It is obvious from these facts--and more like them might be cited--that +mere evaporation, however copious or long continued, does not make the +storm or shower in the locality where it takes place, and _without the +existence and influential agency_ of a counter-trade; and that _reciprocal +action_, whatever it may be, that takes place _between it and the earth_. + +Again, our own experience is conclusive of this. We have no surface-trade +north of 30 deg., and yet a long drought and great evaporation may follow a +wet spring. Belts of droughts and frequent rains occur every year in +different portions of the country side by side, and _the dividing line +follows the course of the counter-trade_, and is sometimes distinctly +marked for weeks. When a change occurs in the counter-trade, whether from +causes existing there or the influence of terrestrial magnetism (in +relation to which we shall inquire hereafter), showers form or storms come +on: until it does they will not. Efforts at condensation will occasionally +appear, but they will be feeble and ineffectual, and occasion a repetition +of the axiom that "all signs fail in a drought." And we may know it from +direct observation. + +The first indications of a storm, and of most if not all showers, are +observable in the counter-trade. These indications, so far as they are +visible, are of course to be looked for in the west; although the +direction and character of the surface-winds are often indicative of these +changes when not visible at the west as we shall see. + +The indications are those of condensation, and vary very much in different +seasons of the year. It is not my purpose in this place to examine them +particularly. They will be alluded to hereafter under the head of +prognostics. Suffice it now to say, then, that whether it be the long +threads or lines of cirrus which occur in the trade in the winter after a +period of severe cold, following the interposition of a large volume of N. +W. cold air and the elevation of the counter-trade; or the forms of cirrus +which occur at other times and other seasons; or whether it be the +ordinary bank at night-fall, or the evening condensation which makes the +"circle" around the moon, or the morning cirro-stratus haze which +gradually thickens, passes over and obscures the sun, all which may be +followed by the easterly scud and winds: they are alike condensation in +the trade, the advance or forming condensation of a storm or showers. + +The state of the weather, whether hot or cold, is extensively affected by +this trade current. As we have already suggested, the mere presence of the +sun in its summer solstice, or its absence in winter, is not an adequate +cause of all the sudden and various changes to which we are subject. The +state of the counter-trade, which is always over, or _within influential +distance of us_, and sometimes probably in contact with us--the nature of +the surface-winds which it is at any given time creating and attracting +around us, and the electric condition of the surface-atmosphere _induced_ +by it, or by the immediate action of the earth's magnetism, produce those +sudden changes which mark our climate. When no intervening surface-winds +elevate it above us, and there is no storm or other condensation within +influential distance, it induces the gentle balmy S. W. wind of +spring--the cooling S. W. wind of summer--the peculiar Indian summer air +of autumn, or the comparatively moderate, although cold, open weather of +winter. If there be a partial tendency to condensation in it, the cumuli +form under the magnetic influence excited by the sunbeams from ten to +three o'clock in the day, and float gently away to the eastward, +disappearing before night-fall. If the disposition to condensation is +stronger, whether inherent or induced by an increased local activity of +terrestrial magnetism, these cumuli will increase toward night-fall, or +earlier, and terminate me showers; and if it is in a highly electrical +state, the still oppressive sultriness which precedes the tornado, and +that devastating scourge may appear. If this disposition to condensation +becomes extensive, cirri form and run into cirro-stratus, or they extend, +coalesce, and form stratus; the surface-wind will be attracted under them, +the thermometer fall in summer or rise in winter, and a storm begin. +Intense action and sudden cold may exist in and under this counter-trade +over the southern portion of the country, while all is calm, warm, and +balmy at the north. Heavy snow storms sometimes pass at the south when +there are none at the north, and a corresponding state of the weather +follows. If a large body of snow fall at the north, the winter is cold, +regular, and "old fashioned;" if little snow falls at the north and more +at the south, the winter at the north is open and broken. I have known the +ice make several inches thick at Baltimore and Washington, when none could +be obtained for the ice-houses on the Connecticut shore of Long Island +Sound. In short, although heat and cold are mainly dependent upon the +altitude of the sun, aided by the other arrangements we have alluded to, +yet the counter-trade, and the reciprocal action which takes place between +it and the earth, are most powerful agents, mitigating the rigors of +winter, bringing about the changes from cold to warm weather which the +sun is too far south to produce. And on the other hand, by this reciprocal +action, producing the electrical phenomena, the gusts, the tornadoes, the +hail storms, and the cool seasons of summer, and the period of intense +cold in winter. + +_All our surface-winds, except the light, peculiar W. S. W. wind which is +felt where the counter-trade is in contact with the earth, and which is a +part of it, and perhaps the genuine N. W. wind which is very peculiar, are +incidents of the trade, and are due to its conditions and attractions._ We +have already said this was true of the easterly wind and scud of a +storm--it is alike true of all. The storm winds east of the Alleghanies +are usually, though not always, from the eastward. They are sometimes from +the southward, as they doubtless are still more frequently in the interior +of the continent. + +There is occasionally a southerly afternoon wind, followed by short rains +in spring and fall, or a succession of showers in summer, which is rather +a precedent wind than a storm wind; blowing toward and under an advance +portion of the storm at the north, and hauling to the eastward when the +rain sets in, or to the westward when the showers reach us. + +When there are no storms, or showers, or inducing electric action in the +counter-trade, within influential distance to disturb the surface +atmosphere, it is calm. If a storm approaches, or forms within inducing +distance, the surface atmosphere is _affected_ and _attracted toward the +storm_, from one or more points, and "blows," as we say, toward and under +it. It commences blowing first nearest the storm, and extends as the +storm travels, or becomes more intense and extends its inducing influence. +I have repeatedly noticed this in traveling on steamboats and railroads +running _toward_ or _from_, and in several instances _through_ a storm, +and telegraphic notices and other investigations prove it. The point from +which the surface atmosphere is attracted and blows, depends very much +upon the position of the storm in relation to bodies of water and the +point of observation, and its shape; and the force with which it may blow +will depend much upon its intensity. + +Let us take an instance or two by way of illustration of all these points; +and as I have given instances of summer in the introduction, we will take +those of winter. It is January of an "old fashioned winter;" the snow is +about three feet deep in Canada, about one foot in Southern New York, and +a few inches in Philadelphia, and so extends west to the Alleghanies at +least. For several days the sky has been clear, the thermometer rising in +the day-time, in the vicinity of New York to about 25 deg. Fahrenheit, falling +at night to about 6 deg., with light airs from the N. W. during the middle and +latter part of the day; the counter-trade and the barometer both running +high; cold but pleasant, steady, winter weather. There is a warm +south-east rain and thaw coming, as one or more such almost invariably +occur in January. How coming? The sun is far south, and shines aslant, but +through a pure and windless atmosphere; he has tried for several days to +melt the snow from the roof; a few icicles are pendant from the eaves; +but the body of the snow is still there. How can a thaw come? not from the +sun, surely. No, indeed, not from the action of the sun directly, upon our +country, nor from the Atlantic or the Gulf Stream which is off our coast. +But a portion of the current of counter-trade is coming, heated by his +rays and the warm water in the South Atlantic, in an intense +magneto-electric state, capable of inducing an electro-thermal change in +the surface atmosphere which it approaches, and of being reciprocally +acted upon by the north polar terrestrial magnetism. It is now over +Northern Texas and Western Louisiana, it will be here day after tomorrow. +The day passes as the day previous had passed; the sleigh-bells jingle +merrily in the evening; the moon shines clear all night; the storm is +coming steadily on, but its influence has not reached us, and the morning +and midday are like those which preceded it. As nightfall approaches, +however, the thermometer does not fall as rapidly as on the day previous; +the sun shines dimly and through lines of whitish cirrus cloud extending +from the horizon at the west, appearing darker as the sun descends and +shines more _horizontally_ through them--perhaps mainly in the N. W.--and +which extend up and over toward the E. N. E. The air next the earth begins +to feel raw; it is changing, not from warm to cold, but _electrically_ +from positive to negative; and dampening, from a tendency to condensation +by induction, as we shall see--the same condensation which in warm +weather may be seen on flagging stones, and walls, and vessels containing +cold water. The advance cirrus condensation of the storm is over us and +affecting us; the earth too is affecting the adjacent atmosphere by action +extended from beneath the storm. Still there is no wind, although sounds +seem to be heard a little more distinctly from the east, and so ends the +day. Evening comes, and the moon wades in a smooth bank of cirro-stratus +haze, with a very large circle around her; the cirrus bands of haze have +coalesced and formed a thin stratus. The storm is coming steadily on, its +condensation is seen to be thicker as it approaches, it is now raining +from one hundred to one hundred and fifty miles to the west, but we do not +know it. + +That it is about to storm all believe, for all are conscious of a change. +The candle if extinguished will not relight as readily, if at all, on +being blown; there is a crackling almost too faint for snow in the fire; +the sun did not set clear; the old rheumatic joints complain, and the +venerable corns ache. + +Morning comes, and the storm is on. The wind is blowing from the S. E., +the scud are running rapidly from the same quarter to the N. W., the +thermometer continues rising, and it rains. The storm has reached us and +the thaw has commenced. Gradually, as the densest portion of the storm +cloud reaches us, it darkens; the scud are nearer the earth, and run with +more rapidity; the rain falls more heavily and continuously, and by the +middle of the day a thick fog has enveloped the earth; the wind is dying +away, and the trade itself, with its southern tendency to fog, has settled +near us; the barometer has fallen, the thermometer is up to fifty degrees, +the water is running down the hills, the snow is saturated with water and +is disappearing under the influence of the fog, the rain, and the warm +air. Evening comes; the south-east wind and the rain have ceased; the rain +clouds have passed off to the eastward; the fog has followed on and +disappeared; there is a light trade air from the S. W.; the moon shines +out, and a few patches of stratus, broken up into fragments and melting +away, are following on in the trade: the storm is past. + +Hark! to the tones of Boreas as he bursts forth from the N. W., and +rushing, whistling, howling, dashes on between the trade and the earth, +following the storm. Now the barometer rises rapidly, the thermometer +falls, and in an incredibly short time all is congealed, and cold and +wintery as before. The cold N. W. wind has again interposed between the +trade and the earth; the trade is elevated a mile or more above it and is +entirely free from its influence and from condensation; the deep blue of a +sky "as pure as the spirit that made it" is over us, and steady winter +reigns again. + +It is obvious that there was nothing in the action of the sun upon our +snow-clad country, to induce the thaw or the storm. It began, continued, +approached, and passed off to the N. E. in the counter-trade. The S. E. +wind which existed every where within its influence: in the interior +States, Missouri, Illinois, Indiana, Ohio, Michigan, and in Canada, as +well as upon the Atlantic coast, commencing in the former earlier than +upon the last, was the result of its induction and attraction. Of the N. +W. wind that followed we shall speak hereafter. If any one doubts whether +this be a true sketch let him examine the investigation of a storm +published by Professor Loomis, or observe for himself hereafter. If, +however, the storm of Professor Loomis is referred to, it should be +remembered that his notes show the occurrence of a slight distinct snow +storm at the N. W. stations one day in advance of the principal storm. The +latter appears first as rain at Fort Towson, on the nineteenth, moving +north and curving to the east--its center passing near St. Louis, and +south of Quebec, and the whole storm enlarging as it advanced. + +Take another instance. Since the thaw it has not been quite as cold as +before; but the rain-soaked snow is hard and solid, the ground, where the +snow was blown or worn off, icy and slippery--the thermometer falls during +the night to about 12 deg., and rises to about 30 deg.; the sun makes no +impression upon the snow; the firmament is of the deepest blue, the +borealis at night vivid. "O, for a storm of some kind, to mitigate the +still severe cold;" for the thaw has made us more sensitive, and storm +winds do blow warm in their season. But patience, it will come. Another +day, or two, perhaps, pass: the sun rises as usual, the thermometer has +the same range still. "Long cold snap," we exclaim; "how long will it +last?" + +A change is coming, but this time it will snow. About an hour or two after +sunrise the cirrus threads are discoverable again in the west, but now +they are most numerous in the S. W. As the day passes on they thicken and +advance toward the E. N. E., the sun begins to be obscured, the +thermometer rises, and it slowly "_moderates_." There is a snow storm +approaching from the S. W. + +But the thermometer rises slowly; it must get up to 26 deg. or 28 deg. before it +can snow much. I have known in one instance, at Norwalk, a considerable +fall of snow, although much mingled with hail, when the thermometer stood +at 13 deg. above zero, and one, a moderate fall, some two inches, with it at +24 deg., but these were exceptions. The snow range of the thermometer on the +parallel of 41 deg. north latitude, and south of it, is from 26 deg. to 30 deg. above +0 deg.; when colder or warmer it may snow to whiten the ground, or perhaps +barely cover it, but usually rains or hails. We have seen that in the +polar regions, according to Dr. Kane, it is about zero, but the rise of +the thermometer there, previous to the snow, was about the same as here, +_i. e._, from 15 deg. to 25 deg.. This fact is instructive. Since the foregoing +was written, and on the 7th of February, 1855, a snow-storm of +considerable length set in, with the thermometer at 5 deg., and continued more +than twenty-four hours, the thermometer gradually rising. The snow was +very fine, like that described by Arctic voyagers as falling in extreme +cold weather. + +As the dense and darker portions of the storm approach, and although the +sun is obscured, and the ground frozen, it continues to moderate, and at +evening, when the thermometer is up to 28 deg., and the dense portion of the +storm has reached us, gently and in calmness the snow begins to fall. +Perhaps a light air following the storm, or the presence of the trade near +the earth, at first inclines the snow-flakes to the eastward. This is +frequently so at the commencement of snow storms. Ere long, however, the +wind rises from the N. E., and the snow is driven against the windows, +rounded and hardened by the attrition of its flakes upon each other, in +their descent through the eddying and opposite currents. The next day we +rise to witness a heavy fall of snow, perhaps, and a continued driving N. +E. storm, in full blast; the snow whirling and settling in drifts under +the lee of every fence or building. + +Can it be, you ask, that this driving wind is but an _incident_ of the +storm? the result of _attraction_, while the storm clouds are sailing +quietly and undisturbed on in the counter-trade above, directly over the +gale which is blowing below? It is even so. Nor has it "backed up," as it +is termed by those who have ascertained that it has commenced snowing +first, and cleared off first, at a point west of them. You saw, or might +have seen, the cirro-stratus cloud passing to the E. N. E. in the +afternoon, and until the snow-flakes filled the air, and the clouds became +invisible. You may still see that the wind will die away before the storm +breaks, and "come out" gently from the S. W., unless it should back into +the northward and westward, and in either event you may see the last of +the storm clouds, as you did see, or might have seen the first of them, +pass to the eastward. Toward night the wind dies away, and the storm +passes off abruptly, or the sky becomes clear in the N. W. Now you may see +the smooth stratus storm cloud, continuous, or breaking up into fragments +and passing off to the east, even at the edge which borders the clear sky +in the west or north-west, to be followed that evening or the next day, by +the north-west wind and its peculiar fair-weather scud. + +I have given these as instances illustrating the manner in which rain and +snow storms originate the surface easterly winds in winter. + +But it must not be supposed that they commence with precisely the same +appearances in every case in winter; much less in summer. There is very +great diversity in this respect, in different seasons, and in different +storms during the same season. A great many different and accurate +descriptions might be given, if time and space would permit, which all +would recognize as truthful. Very frequently in summer, and sometimes in +winter, the wind will set in from the eastward, and blow fresh toward a +storm, before the condensation in the trade, which forms the eastern and +approaching edge of the storm, has assumed the form of a distinct cloud. +Not unfrequently, when it is calm next the surface, a narrow stratum of +easterly wind, a half a mile or a mile above the earth, may be seen with a +continuous fog, condensing, but not in considerable patches like the +usual scud, running with great rapidity toward the storm. Such a stream of +fog blew with great rapidity for thirty-six hours toward the storm which +inundated Virginia and Pennsylvania, in 1852, and carried away the Potomac +bridge at Washington. Such a stream of fog was visible the evening before +the great flood of 1854, which inundated Connecticut, and curried away so +many railroad and other bridges. I have also seen such a stream of fog +running at about the same height, when it was calm at the surface, from +the S. W. toward a violent storm which formed over central New +England--and from the north toward a heavy storm passing south of us. Such +strata form, as far as I have been able to discover, the _middle current_ +of storms which are accompanied with very heavy falls of rain. These +double currents are much more common than is supposed. East of the +Alleghanies, short and heavy rain storms, which commence north-east, +hauling to the south and lighting up about mid-day _after a very rainy +forenoon_, frequently have a S. E. or S. S. E. middle current of this +character, which involves the whole surface atmosphere when the storm has +nearly passed, and the N. E. wind dies away, and the wind seems to haul to +the S. S. E. and S.; so that it is rather the prevalence of a _different_ +and _coexisting current_, than a hauling of the _same wind_, which marks +the period of lighting up in the south. + +Sometimes the easterly wind will set in and blow a day or two before the +border of the storm reaches us. Sometimes the storm is passing, or will +pass, in its lateral southern extension, south of us, and the +condensation in the trade extends over us sufficiently dense to induce an +easterly current beneath it, but not dense enough to drop rain, and then +we have a dry north-easter. I can not, within the limits I have +prescribed, allude to all the peculiarities attending the induction and +attraction of an easterly wind, by the storm in the counter-trade. They +are readily noticeable by the attentive and discriminating observer, and +their existence and cause is all with which I have to do at present. + +Winds from the north, or any point from N. N. E. to N. N. W., are +comparatively infrequent in the United States, east of the +Alleghanies--though it is otherwise in the vicinity of the great lakes. + +Sometimes the wind "backs," as sailors term it, during a N. E. storm, from +the N. E. through the N. N. E., N., and N. N. W. to N. W. When this takes +place, it is toward the close of the storm. Occasionally, though very +rarely, it continues to storm after the wind has passed the point of N. N. +E., and until it gets N. W. I have known a few instances in the course of +thirty years, and but a few. They are exceptions--rare exceptions. When +the wind thus backs from the N. E. to the N. W. through the N., you may be +very certain that the body of the storm, or at least the point of greatest +intensity and greatest attraction, is at the time passing to the southward +of you. This is most commonly the course of the wind when the storm +extends far south and lasts several days, and does not extend north far, +or if so, with much intensity, beyond the point of observation. The +change of the wind is explained by the situation of the focus of intensity +and attraction, to the south of the observer, and its passage by on that +side. + +Probably in locations further north and (as I think I have observed) south +of the lakes, it may be more frequent than upon the parallel of 44 deg. east +of the Alleghanies (which is as far north as I have observed), inasmuch as +the further north the locality, the more likely storms and other +disturbances in the counter-trade will be to pass to the southward of it. + +Between the N. E. and S. E. the wind may blow from any point, before and +during storms, and in a clear day in the morning, as a light variable +breeze, or, after mid-day, toward approaching showers. I have known it +blow all day during a storm from due east; to change back and forth +between south-east and north-east, and to blow for hours from any +intermediate point--as different portions of the storm were of different +intensity, and exerted a more or less powerful inducing influence; and +doubtless this often takes place at sea. It depends upon the situation of +the focus of attraction of the storm, its shape relative to the particular +locality, and with reference to the atmosphere east of it, and peculiar +local magnetic action; or, as is sometimes the case in low latitudes, is +owing to the fact that the storm is made up of many imperfectly connected +showers, which have different force, and induce changeable and baffling +winds. + +The inducing and attracting influence of the approaching storm is exerted +sooner, and with most force, upon the surface atmosphere, over bodies of +water like the ocean and the lakes. Thus, the wind will set from the +eastward toward an approaching storm out upon Long Island Sound, for hours +before it is felt upon either shore; and when all is calm in the evening +on land, and often before the moon forms a halo or circle in the milky +condensation of the approaching storm, or any sign of condensation is +visible, the breaking of the waves upon the shores may be heard. Doubtless +this may be observed on the shores of the Atlantic at other points. + +This power of attracting the surface atmosphere from bodies of water like +the ocean and the great lakes, will account for two apparent anomalies, +mentioned by Mr. Blodget in a valuable and instructive article read to the +Scientific Convention, in 1853, regarding the annual fall of rain over the +United States. + +First--the influence of mountains in extracting the water from the +atmospheric currents which pass over them, is well known and readily +explainable. Mr. Blodget, however, found that the source of our rains, +whatever it might be, when it reached the Alleghanies, was so far +exhausted of its moisture that those mountains extracted less from it than +fell to the westward, by some five to ten inches annually; and that the +fall of rain upon them was less than upon the Atlantic slope eastward of +them, to the ocean. This does not accord with observation elsewhere, but +is easily explained. As the storm approaches the ocean, it attracts in +under it the surface atmosphere of the ocean, loaded with vapor, +condensing in the form of fog and scud, as it becomes subject to the +increasing influence of the storm. Although the scud and fog would not of +itself make rain, it aids materially in increasing the quantity of that +which falls through it. The drops, by attraction and contact, enlarge +themselves as they pass through, in the same manner as a drop of water +will do in running down a pane of glass which is covered with moisture. +The small drop which starts from the upper portion of a fifteen-inch pane, +will sometimes more than double its size before it reaches the bottom. _It +is by this power of attracting the surface atmosphere, which contains the +moisture of evaporation, under it, and inducing condensation in it, that +the moisture of evaporation which rarely rises very far in the atmosphere +is made to fall again during storms and showers._ This attraction of a +moist atmosphere from the ocean accounts for the excess of rain on the +east of the Alleghanies, compared with its fall upon them. So the great +valley of the Mississippi is comparatively level, and less of its water +runs off than of that which falls upon the Alleghanies. There is, +therefore, more moisture of evaporation in the atmosphere of the former to +be thus precipitated and add to the annual supply of rain upon that +valley, and it exceeds that which falls upon the Alleghanies. Those +mountains, too, are elevated but about 1,500 feet above the table-lands at +their base, and exert little influence on the counter-trade. If they, were +6,000 or 8,000 feet high, a different state of things would exist. + +Second--Mr. Blodget found the quantity of rain which fell in Iowa, and to +the south and west of the lake region, to be greater than fell over the +lake region itself. This is doubtless in part owing to the same cause. The +counter-trade, in a stormy state, attracts the surface atmosphere from the +lake region, with its evaporated moisture, before it arrives over it, and +therefore more rain falls S. W. of the lake region than upon it. This +power of attracting the surface wind of the ocean in under it, produces +the heavy gales which affect our coast, and which are rarely felt west of +the Alleghanies to any considerable degree; and a storm coming from the W. +S. W., extending a thousand miles or more from S. S. E. to N. N. W., may +have the wind set in violently at S. E. on the _southern coast first_, and +at later periods, successively, at points further north, and thus induce +the belief that the storm traveled from south to north. + +Mr. Redfield finding that some of the gales which he investigated, +particularly that of September 3d, 1821, did not extend far inland, and +commenced at later periods regularly, at more northern points, concluded +that the gale traveled along the line of the coast to the northward. In +this, and in relation to the storm of 1821 (and perhaps some others), he +has been deceived. My recollections of that storm are accurate and +distinct. But I shall recur to this again when I come to speak of his +theory. + +Toward storms, or belts of showers which would be storms if it were not +summer and the tropical tendency to showers active in the trade, which +pass mainly to the north of us, or commence north and pass over us, +condensing south while progressing east, the wind may commence blowing +before the body of the storm reaches us, from any point between south by +west and south east, particularly in the summer season and in the +afternoon. When the rain in a storm of this character sets in, in the +night, it will sometimes haul into the S. E., if the focus of attraction +be situated north of us, and so remain until just before the storm is to +break. + +There are, however, a class of southerly summer winds which deserve more +particular notice. For two or three months in the year--say from the +middle of June to the 20th of August--storms on the eastern part of the +continent, except in wet seasons, are rare, and most of our rain is +derived from showers. During these periods belts of drought are frequent, +sometimes in one locality, and sometimes in another, extending with +considerable regularity from W. S. W. to E. N. E. in the course of the +counter-trade, while rain falls in frequent and almost daily showers to +the northward or southward of them. If the daily rains are at the north, +over the belt of drought, S. S. W. and S. W. by S. winds blow, sometimes +with cumuli or scud, during the middle of the day and afternoon, to +underlie the showery counter-trade on the north of the line of drought. +Thus, sometimes nearly every day for several days, the evaporated moisture +of the dry belt will be carried over to increase the store of those who +have a sufficient supply without. During the latter part of the afternoon +the clouds in the west may look very much like a gathering shower, but the +attractions of the counter-trade fifty or one or two hundred miles to the +north, will absorb them all, and at nightfall the wind will haul to the S. +W. on a line with the counter-trade, and die away. + +If there be a drought on any given line of latitude, and frequent showers +or heavy rains at the south of it, although there may not be a like +surface-wind, with cumuli and fog, blowing from the north toward it, yet a +general, gentle set of the atmosphere, from the N. N. W., or N. W., or +other northerly point, toward the belt of rains, some distance above the +earth, will often be observable, with a barometer continually depressed, +and perhaps a cool atmosphere. + +During set fair weather, when the attracting belt of rains is far north, +on the north shore of Long Island Sound, the wind, like a sea breeze, will +set in gently from about S. S. E. or S. by E. in the forenoon, blowing a +gentle breeze through the day, and hauling to W. S. W. on a line with the +trade at nightfall, and dying away. During a drought I have known this to +happen for seventeen successive days. It is obvious to an attentive +observer that this is the result of the influence of the sun in exciting +the magnetic influence of the earth, and producing a state of the trade +not unlike that which induces the formation of cumuli, and which attracts +the surface atmosphere from the Sound in over the land: for the _tendency +to cumulus condensation precedes the breeze_, and the breeze is often +wanting in the hottest days where no such tendency to the formation of +cumuli exists. The same is true of sea breezes elsewhere. They do not blow +in upon some of the hottest surfaces. Where they do exist, they do not +always blow, but are wanting during the hottest days; and careful +observers have identified their appearance with the formation of cumuli, +or other condensation, upon the hills inland. They are not, therefore, the +result of ascending currents of heated air. + +The received theory regarding sea and land breezes is a mistaken one in +another respect. There is no such thing as a land wind corresponding in +force to, and the opposite of, the sea breeze--occasioned by the +comparative warmth of the ocean. These breezes blow mainly within the +trade-wind region. Of course they are either beneath the belt of rains or +the adjoining trades. They are said to be, and doubtless are, most active +and strongly marked on lines of coast, particularly the Malabar coast, and +where the trade-winds are drawing usually from them. In the day-time, when +the action of the sun increases the action of the magnetic currents upon +the land, or there are _elevations inland_ which approach the +counter-trade, and especially if it is elevated near the coast, as the +Malabar coast is by the Ghauts, the attraction of this atmosphere over it +_reverses the trade_, or inclines it in upon the land, and it blows in +obliquely or perpendicularly, according to the relative trending of the +coast and the direction of the surface-trade. Thus, where islands are +situated within the range of the trades, the latter will be _reversed_ +during the day on the _leeward_ side, but continue to blow as land winds +during the night. So they are sometimes deflected in upon the land on the +sides, during the day, and in like manner return to their course in the +night. So, too, the north-east trades of Northern Africa, are occasionally +(though feebly where the coast is flat) deflected during the day-time, and +blow in as N. W. winds. Upon the southern coast of Africa the S. E. trade +is deflected, and blows in as a S. W. wind. Upon the south-western coast +of North America, the N. E. trades are deflected in like manner, and so +are the S. E. trades upon the western coast of South America. Where the +coast mountain ranges are very elevated, as upon the western coast of the +American continent, this attracting influence and consequent deflection +extends to a considerable distance seaward, and hence the westerly winds +of California, etc. It must be understood that we are now speaking of the +winds which blow within the range and during the existence of the +trade-winds or the presence of the dry belt--for the trades are not always +perceptible on the land. Captain Fitzroy thus describes the sea breezes of +the western coast of Peru, at 23 deg. south latitude. "The tops of the hills +on the coast of Peru are frequently covered with heavy clouds. The +prevailing winds are from S. S. E. to S. W., seldom stronger than a fresh +breeze, and often very slight. _Sometimes during the summer, for three or +four successive days, there is not a breath of wind, the sky is +beautifully clear, with a nearly vertical sun._ On the days that a sea +breeze sets in, it generally commences about ten in the morning, then +light and variable, but gradually increasing till one or two in the +afternoon. From that time a steady breeze prevails till near sunset, when +it begins to die away, and soon after the sun is down there is a calm. +About eight or nine in the evening _light winds_ come off the land, and +continue till sun-rise, when it again becomes calm until the sea breeze +sets in as before." + +To illustrate this further, I take the following letter from Professor +Espy's Philosophy of Storms: + + CLINTON HOTEL, N. Y., Dec. 20, 1839. + + TO PROFESSOR ESPY, + + DEAR SIR,--Understanding you are desirous of collecting curious + meteorological facts, I take the liberty of communicating to you what + I saw in the month of December, 1815, at the Island of Owhyhee. I lay + at that island in the Cavrico Bay,[3] in which Captain Cook was + killed, three weeks, and every day during that time, very soon after + the sea breeze set in, say about nine o'clock, a cloud began to form + round the lofty conical mountain in that island, in the form of a + ring, as the wooden horizon surrounds the terrestrial artificial + globe, and it soon began to rain in torrents, and continued through + the day. In the evening the sea breeze died away and the rain ceased, + and the cloud soon disappeared, and it remained entirely clear till + after the sea breeze set in next morning. The land breeze prevailed + during the night, and was so cool as to render fires pleasant to the + natives, which I observed they constantly kindled in the evening. I + was particularly struck with the phenomena of the cloud surrounding + the mountain, when none was ever seen in any other part of the sky, + and none then till after the sea breeze set in, in the morning, which + it did with wonderful regularity. The mountain stood in bold relief, + and its top could always be seen from where the ship lay, above the + cloud, even when it was the densest and blackest, with the lightning + flashing and the thunder rolling, as it did every day. I passed up + through the cloud once, and I know, therefore, how violently it + rains, especially at the lower side of the cloud. This rain never + extends beyond the base of the mountain;[4] and all round the horizon + there is eternally a cloudless sky. The dews, however, are very + heavy, and there seems to be no suffering for want of rain. That this + state of things continues all the year, I have no doubt, from what an + American, by name Sears, who had spent four years there, told me; he + had seen no change in regard to the rain. + + CALEB WILLIAMS. + + Providence, R. I. + +Similar citations might be made to show that the sea breeze is induced by +the same cause which forms the clouds over the land--that it is frequently +wanting for three or four days under a vertical sun, and that the land +breeze blows gently and not with corresponding force where there is no +surface trade, or where it is deflected, not reversed. + +A succession of showers passing across the country to the north, within +one hundred to one hundred and fifty miles, almost always produces a +southerly wind to the southward of them. There is more that is peculiar +about these belts of showers. Although they consist of large +highly-electrified cumuli, there is a strong tendency to cirro-stratus +condensation in the lower part of the trade over them; and it is that +condensation rather than the cumuli, which attracts the surface atmosphere +from the south. They would be storms, if the atmosphere had not a +summer-tropical tendency to showers. There is, too, a tendency in these +belts to extend to the south, and it is generally, as far as I have +observed, the extension southerly of those belts, by the formation of new +showers which terminate the "hot spells" or "heated terms" of mid-summer. +The very oppressive and fatal one of the summer of 1853, was, in +character, a type of all--although exceeding them in severity. The first +three or four days were calm, hot, and smoky--an appearance which attends +all similar periods more or less, refracting the red ray of the light, and +giving the sun a peculiar dry-weather, red appearance. (This smoky haze is +usually atmospheric, and occasionally seen even in March, although not +unfrequently fires in the woods fill the air with actual smoke, and very +much increase it, and when this is so, the odor of the smoke is often +perceptible.) Then we began to have a fresh south-west by south breeze in +the day-time, hauling to the south-west, and dying away at nightfall. The +next day, the tendency to condensation and consequent belt of showers +having extended further south and approached nearer to us, the S. S. W. +wind blew _fresher_ toward it, and _did not die away at nightfall_. During +the evening the reflection of the lightning playing upon the tops of the +thunder clouds, just visible at the north (heat-lightning, it is termed, +because supposed to be unaccompanied by thunder, but in reality lightning +reflected from clouds at too great a distance for the thunder to be +heard), and the continuance of the southerly wind after nightfall, gave +sure evidence of the coming showers the next day, and an end of the +excessive heat for that time. So ended both of those long-to-be-remembered +"heated terms" of 1853. + +The same is probably true of the interior of the country every where. +Lieutenant Maury, in the course of his investigations, and in order to +ascertain the direction of the winds in the Mississippi valley during +rain, addressed a number of gentlemen, and received their replies, which +are published with his wind and current charts. Several answered, among +other things, that, "whenever the lightning appears to linger at the north +at eventide, rain almost invariably follows speedily; not so in the +south." Thus it frequently is with us. If, during a hot, dry time, of a +few days continuance, the lightning so lingers in the evening, and the +wind continues to blow _fresh_ from the southward _after nightfall_, +showers will generally follow within forty-eight hours, most commonly the +next day, and a cool N. N. W. or N. W. wind with a favorable change ensue. +Such, at least, has been the result of my observation for many years. + +Indeed this seems to be the general law in summer in the Mississippi +valley, where the easterly winds are not so common as with us. To +illustrate this further, I copy from a recent work by T. Bassnett, +entitled the "Mechanical Theory of Storms," two short extracts, showing +the manner in which belts of showers extend southerly, while progressing +north-eastwardly, at Ottawa. The first occurred in August, 1853; the last, +December, 1852. The first was a belt of showers; the latter would have +been in August, but the lateness of the season changed its character +somewhat, though not entirely, to a more regular rain, especially toward +the close. + + "AUGUST 6th.--Very fine and clear all day: wind from S. W.; a light + breeze; 8 P.M. frequent flashes of lightning in the northern sky; 10 + P.M., a _low bank of dense clouds in north_, fringed with cirri, + visible during the flash of the lightning; 12 P.M., same continues. + + "7th.--very fine and clear morning; wind S. W. moderate; noon, clouds + accumulating in the northern half of the sky; _wind fresher_, _S. + W._; 3 P.M., a clap of thunder over head, and black cumuli in west, + north, and east; 4 P.M., much thunder and scattered showers; six + miles west rained very heavily; 6 P.M., the heavy clouds passing over + to the south; 10 P.M., clear again in north. + + "8th.--Clear all day; wind the same (S. W.); a hazy bank visible all + along on _southern horizon_. + + "DECEMBER 21st, 1852.--Wind N. E., fine weather. + + "22d.--Thick, hazy morning, wind east, much lighter in S. E. than in + N. W.; 8 A.M., a clear arch in S. E. getting more to south; noon, + _very black in W. N. W._; above, a broken layer of cirro-cumulus, the + sun visible sometimes through the waves; wind around to S. E., and + fresher; getting thicker all day; 10 P.M., _wind south, strong_; + thunder, lightning, and heavy rain all night, with strong squalls + from south. + + "23d.--Wind S. W., moderate, drizzly day; 10 P.M., wind west, and + getting clearer." + +It is obvious that the showers at the north passed east on the evening of +the 6th of August; that new showers, taking the same course, originated in +the north, but more southerly next day, with S. W. wind, and that they +passed east, and others formed successively further south, which passed +over the place of observation late in the afternoon, and that others +formed south and passed east during the night and next day, visible in a +bank on the southern horizon. + +Later or earlier in the spring and autumn, these brisk afternoon +southerly winds continuing after nightfall, indicate moderate rains from a +rainy belt extending in a similar manner, without the cumuli and thunder +which attend those of mid-summer. I shall recur to this class of showers +and storms when we come to their classification. + +Light surface winds from south-west to west are not often storm-winds, and +are usually those which the trade near the earth draws after it. Sometimes +the trade seems to draw the surface wind from the S. W. and W. S. W. with +considerable rapidity, and some scud a little distance above the earth. +When this is so, it will be found that a storm has passed to the north of +us, or a belt of rains is passing north, which may or may not have +sufficient southern extension to reach us. When there have been heavy +storms at the south in the spring, especially if of snow, the S. W. wind +which the trade draws after it, and which comes from the snowy or chilled +surface, is exceedingly "raw"--that is, damp and chilly, although not +thermometrically very cold. Probably every one has noticed these "_raw_" +S. W. winds of spring. + +Usually, when storms and showers, which have not a southern lateral +extension, pass off, the trade is very near the earth, and a light S. W. +wind or calm follows for a longer or shorter period. Not unfrequently, +however, our N. E. storms terminate with a S. W. wind, shifting suddenly, +perhaps, just at the close of the storm, during what is sometimes called a +"clearing-off-shower," or, more frequently, dying gradually away as a N. +E. wind, and coming out gently from the S. W., following the retreating +cloud of the storm. In such cases it is said to "clear off warm." + +With us the wind rarely blows from the west, except while slowly hauling +from some southerly point to the N. W. It is probably otherwise east of +the lakes and in some other localities to the north-west. + +Occasionally, and most frequently in March, a W. to W. N. W. wind follows +storms, and blows with considerable severity, with large irregular, +squally masses of scud, and sometimes a gale. Such was the character of +the dry gale which crossed the country, particularly Northern New York, in +March, 1854, doing great damage. These westerly winds are always +accompanied by a continued depression of the barometer, and peculiar, +foggy, scuddy, condensation, and should be distinguished with care from +the regular and peculiar N. W. wind, as they may be, by the continued +depression of the barometer, and the character of the scud. They are +doubtless magnetic storms. + +The remaining surface wind, the N. W., the genuine Boreas of our climate, +the invariable fair-weather wind, is one of great interest. It is unique +and peculiar. It is not the left-hand wind of a rotary gale, and has no +immediate connection with the storm. I have known it blow moderately, +fifteen successive days in winter; rising about ten A.M., and dying away +at nightfall. Occasionally, but very rarely indeed, a light wind exists +from the N. W. during a storm, owing probably to a focus of intensity in +relation to some surface the storm covers, like the focus which exhibits +itself as a clearing-off shower near the close of a storm; but the real +fair-weather Boreas is a different affair altogether. Let us observe with +care its peculiarities; they are instructive. + +1st. It rarely blows with any considerable force beneath the trade while +there are storm clouds, or any considerable condensation in it. It does +not interfere with that reciprocal action which takes place between the +trade and the earth, during approaching or existing storms. I have +frequently seen it with its peculiar scud clouds in the N. W., waiting for +the storm condensation of the trade to pass by, that full of positive +electricity it might commence its sports; rushing and eddying along the +surface, licking up the warm, south polar, electric rain, which stood in +pools upon the ground, or rose in steamy vapor from the surface, and with +its cool breath dry up the muddy roads as no degree of heat can dry them. + +The annexed figure (14) shows the appearance of the northern edge of a +stratus storm cloud, passing off E. N. E. at the close of the storm, which +was "_clearing off from the north-west_." It is from a daguerreotype view, +looking W. N. W., taken at eight o'clock in the morning, in the fall of +the year. Near the horizon maybe seen the N. W. scud, forming in the N. W. +wind, which is about to follow the retreating edge of the storm cloud. + +Figure 15 is from a daguerreotype view, taken at eleven o'clock the same +day, when the storm cloud had passed off and its edge remained visible +only south of the zenith, and the north-east scud had risen up and covered +the northern half of the sky, and the wind was blowing a gale from that +quarter. + + +[Illustration: Fig. 14.] + + +Another view was taken about two P.M. of the same day, when the scud had a +very dark, gloomy appearance--as _dark_ and _gloomy_ as those of a Mexican +norther--too dark to represent by a cut. + +Not unfrequently in a moist summer season, after a day of showers or rain, +which have had an extending formation or lateral extension from north to +south, it will commence blowing in the morning, and encourage the +hay-maker with the hope of fine weather. But often before noon, the milky +stratus condensation above with cumuli below, will appear in the trade; +the N. W. wind die away and variable airs from the east or south appear, +to be followed toward night by an enlargement of the cumuli and showers. +It rarely, if ever, blows fresh till the storm condensation of the trade +has passed; or continues to blow after that condensation reappears. When +it commences blowing after a storm, and the northern edge of the storm is +not over us, we may frequently see the latter low down in the S. E. +passing eastward. + + +[Illustration: Fig. 15. NORTH VIEW.] + + +2d. Its scud are peculiar. Every one, probably, has noticed them. They are +distinct, more or less disconnected, irregular, with every form between +those of the easterly scud, cumulus, and stratus, according to the season. +If large, with _dark under surfaces_; forming _rapidly_ and as _rapidly +dissolving_; rarely dropping any rain, sometimes dropping a flurry of +snow, in November or March, oftener than at any other period; sailing away +to the S. E., and casting a traveling shadow as they pass on over the +surface of the earth. Their electricity, particularly when white, is +probably always positive, as that of all whitish clouds is supposed to be. + +3d. _It is emphatically a surface wind._ The incident storm winds, the N. +E. and S. E., frequently _commence blowing_ under the storm, toward its +point of greatest intensity, _up near the line of cirro-stratus +condensation_, evidenced by the running scud; or blow there with most +rapidity, and so continue for hours before the whole surface atmosphere +from thence to the earth becomes involved in the movement; and sometimes +without being felt below at all. Not so with the N. W. wind; it _begins at +the surface_ and blows there with more rapidity than above; it seems to be +attracted by the earth; it interposes between the earth and the trade, +wedging the trade up and occupying its place. It blows under at all +seasons of the year, but most readily and strongly from a surface of snow +whose electricity is always positive. Hence it blows most strongly and +_continuously_ when snow has fallen at the north, and prevails during +winter very much in proportion to the extent and continuance of the +covering of snow which invests the earth in that direction. It follows +after storms, and particularly warm rains, during the autumn, winter, and +spring months, which have a lateral southern extension. Whether it is +increased by the snow from the surface from which it blows, or is caused +by the same magnetic action which causes the great fall of snow, is a +question we shall consider hereafter. + +4th. It does not connect or mingle with the trade current in any way, or +change or divert the course of that current; but interposes between it and +the earth, elevating the trade in proportion to its own volume, above the +influences of the earth (when the trade becomes free from condensation, +and singularly, clear); and raising _proportionately_ the barometer. An +experienced observer can frequently estimate, with considerable accuracy, +the rise of the barometer, by measuring with his eye, (when the clouds +will enable him to do so,) the depth of this interposed N. W. current. The +barometer rarely rises after a storm, for twenty-four or forty-eight hours +if the wind continues at any point from S. W. to W. N. W., but always +rapidly as soon as the genuine N. W. current with any considerable depth +interposes and elevates the trade. + +It will be obvious to every one, I think, certainly, if they will +hereafter study the subject and observe for themselves, that the N. W. +wind does not blow away the storm; and that it follows after it, blowing +over the surface which is uncovered by the storm; rarely, if ever, with +any force when the body of the storm passed south of us; and that it is a +purely surface wind, seemingly attracted by the peculiar magneto-electric +state in which the surface of the earth is left, compared with a snow-clad +surface to the north, by a recent storm, or that peculiar state of the +trade which is left by the action of the storm. It seems to follow that +magnetic wave which, passing from north to south, acts in its course upon +the counter-trade, producing the storm, or belt of showers, and giving +them their southern lateral extension, and will well repay future +telegraphic investigation. Its electricity is intensely positive--that of +the earth by the action of the storm as intensely negative. + +5th. This N. W. wind occurs in all parts of the northern hemisphere, so +far as we have data to determine, and its corresponding wind from the S. +W. occurs in the southern hemisphere. It is identical with a class of the +northers of the Gulf of Mexico, as a brief analysis of the character of +the latter will show. + +1st. The fall and winter _norther_ is a dry wind without rain or falling +weather--so is our N. W. wind. + +2d. It is preceded by a falling barometer; S. E. scud and rain at the +point where it blows, or to the eastward of it. So is ours when it blows a +gale in the fall and spring months, which bear the nearest resemblance in +climatic character to the periods when the northers blow. With this +distinction, however, that our precedent rains either pass over us or to +the southward, the direction of storms being E. N. E.; their precedent +storms passing over or to the eastward of them as they move more to the +northward. + +3d. It is often preceded by a copious dew; so is ours--such dews often +following light fall rains in our climate, and preceding N. W. wind. + +4th. The most peculiar characteristic, however, is that the barometer +rises rapidly and invariably while the norther prevails, and very much in +proportion to its violence. The same is true of our genuine N. W. wind, +and is not true _of any other wind_ on this continent which I have +observed or read of. + +5th. While they are thus alike in these respects, they are unlike in no +respect. + +Mr. Redfield has traced them in _supposed_ connection with storms which +continue from that vicinity across the United States to the E. N. E., and +endeavored to connect them with those storms, as the left-hand winds of a +rotary gale. Obviously, I think, they are identical with our N. W. winds +which also _follow_, indeed, but _are distinct from the storms_. + +There are a class of northers in the Gulf of Mexico--the "Nortes del Muero +Colorado"--sometimes occurring in the summer months, beginning at N. E., +veering about and settling at N. N. W., and as they decline hauling round +by the west to the southward. These winds correspond precisely with the +hurricane winds of the West Indies, and are doubtless the incident winds +of a storm traveling thence to the N. N. W. precisely as our N. E. or E. +N. E gales are incident storm winds to the N. E. storms of our latitude. + +In this connection we will look at the peculiarities of a West India +hurricane. + +"It is not a little remarkable," says Mr. Espy, speaking of the storms and +hurricanes of the West Indies, "that all these storms, and _all others +which have been traced to the West Indies_, traveled N. W. almost at right +angles to the direction of the trade-wind in those latitudes, but very +nearly, if not exactly, in the direction of an upper current of the air +known to exist there toward the N. W." Substantially the same facts have +been repeated by Mr. Redfield, and demonstrated by his able +investigations, both there and in the Eastern Pacific, and are confirmed +by the observations of Edwards, Lawson, and others, while residents there. +It is a matter of surprise that gentlemen like Messrs. Redfield and Espy, +who have certainly displayed great ability in the investigations of +meteorological phenomena, should fail to recognize a more intimate +relation between this upper current and the storms they were +investigating, and to detect the general laws which govern both. The +storms and hurricanes of the West Indies are comparatively of small +diameter, and have little advance condensation. When they pass on to the +south-western portion of North America and curve to the N. E., as they +frequently do, they enlarge in front and at the sides, and their advance +condensation, which is not dense enough to drop rain, extends in some +cases from one to three hundred miles; and the storm itself, by the time +it reaches the Alleghanies, may extend one thousand to fifteen hundred +miles, and perhaps in certain magnetic states of the surface, and +occasionally, may cover the entire portion of the continent, from north to +south. Such, probably, was very nearly the extension of the storm +investigated by Professor Loomis. In the West Indies, however, at the +commencement, they vary from twenty to one hundred miles, or possibly +more, in width. + +First, they are preceded by a hot, sultry and oppressive atmosphere--_as +are electric storms every where_--a peculiar electric state of the earth +and adjacent air. + +Second, the black clouds and lightning which indicate the approaching +hurricane are seen to the S., S. E., and E. S. E., according to the season +of the year, as we see them at the westward. During the rainy season, and +when the storm, as is usual at that period, is small, and the S. E. trade +blows more eastwardly, the wind at the Windward Islands, possibly, may set +in at the north, and back round by the east as it progresses. So Colonel +Reid thinks it sometimes does, at Barbadoes. But when the belt of rains is +south, and the hurricane comes from the south-east, and is larger and more +violent in its action, and the north-east winds prevail, the first effect +is an increase of these trades. Soon, however, the wind hauls to the north +and north-west, in opposition to its course, bearing the same relation to +it that our east and north-east winds bear to storms in the United States; +and the wind hauls around during the passage of the storm to the west, +south-west, and south-east, and at the latter point it clears off. Mr. +Edwards in his History of Jamaica says--and as a resident, his authority +should be decisive as to this Island--"_that all hurricanes begin from the +north_, veer back to the W. N. W., W., and S. S. W., and when they get +around to the S. E. the foul weather breaks up." Doubtless the same is +true of the class of northers of which we are speaking on the Gulf of +Mexico. _But with this class the barometer does not rise during the gale, +and in proportion to its length and violence._ With the other class of N. +W. winds--the northers of winter--it does. + +The following description of two winter northers, copied from Colonel +Reid's valuable work, will illustrate what has been said. _Precisely such +changes from S. E. rains to N. W. winds, with blue sky and detached dark +clouds--fair-weather N. W. scud--occur every autumn in October and +November_, and the falling of the thermometer and rising of the barometer, +after rain, and a change of the wind, are perfectly characteristic. + + ------------------------------------------------------------------------ + 1843. | Wind. |Force.|Weather.| Bar.|Ther.| + ------------------------------------------------------------------------ + Jan. 30.| | | | | | + A.M. 4. |S. S. W. | 2 |b. c. |29.90| 77 |Off Tampico. + Noon. |South. | 5 |b. c. r.|29.86| 76 | {Lat. 23 deg. 41' N., + P.M. 8. |South. | 6 |b. c. r.|29.84| 76 | {Long. 94 deg. 50' W. + Jan. 31.| | | | | | + A.M. 4. |S. Easterly.| 3 |b. c. |29.90| 74 | {Between 6 and 10 + | | | | | | {A.M., wind was + | | | | | | {variable. + Noon. |N. by W. | 9 |c. q. w.|29.96| 76 |Norther commenced at + | | | | | | 10 A. M. + P.M. 8. |N. N. W. | 9 |c. |30.09| 73 |Lat. 22 deg. 36' N., + | | | | | | Long. 95 deg. 48' W. + Feb. 1. | | | | | | + A.M. 4. |N. N. W. | 7 |c. g. |30.29| 63 |Lat. 22 deg. 9' N., + | | | | | | Long. 94 deg. 50' W. + Noon. |Westerly. | 6 |c. |30.30| 67 | + P.M. 8. |Calm. | 0 |c. |30.26| 67 | + ------------------------------------------------------------------------ + Feb. 14.| | | | | | + A.M. 4. |S. E. | 3 |b. c. r.|29.66| 73 |At Sacraficios. + Noon. |S. W. | 4 |b. c. |29.62| |Norther comc'd at 5.30 + | | | | | | P.M. + P.M. 8. |N. W. by N. | 10 |c. q. u.|29.72| 65 | + Feb. 15.| | | | | | + A.M. 4. |N. W. by N. | 10 |c. q. u.|30.10| 61 | {Gale moderated and + | | | | | | {again freshened + | | | | | | {about 8 A.M. + Noon. |N. W. by N. | 10 |c. g. q.|30.19| 61 | + P.M. 8. |N. W. | 4 |c. g. |30.20| 65 | + Feb. 16.| | | | | | + A.M. 4. |N. W. | 3 |q. |30.18| 62 | + P.M. 8. | N. N. W. | 2 | c. g. |30.21| 66 | + ------------------------------------------------------------------------ + + b. indicates blue sky--c. detached clouds--r. rain--v. visibility of + objects--q. squalls--w. wet dew--u. ugly threatening appearance--g. + gloomy weather. + +The exact counterpart of the first norther may be observed with us every +fall. On the 30th January, with a rising thermometer and falling +barometer, there was rain at midday. The night following was moist--the +next day, about ten A.M., the wind came out N. W., with squalls and gloomy +weather, a falling thermometer, and rising barometer. + +The norther of Feb. 14th differed from the other only in regard to the +time of the day when it commenced; the order of events was the same. The +rain fell in the night--it cleared off early in the day, and the norther +followed in the afternoon. This also is frequently the case with us, as +every one may observe. + +This brief notice of the surface winds of our climate would be incomplete +without a description of those of the thunder-gust and tornado. + +The former is exceedingly simple. The showers, which are accompanied with +much wind, form suddenly in hot weather, and have a considerable advance +condensation (frequently with obvious lateral internal action), extending +eastwardly from the line of smooth cloud from which the rain is falling, +or rather where the falling rain obscures the inequalities of the cloud. +_The gust is never felt until the advancing condensation has passed over +us_, when it takes the place of the gentle easterly breeze which +previously set toward the shower. _The gust ceases as soon as the cloud +has passed._ It is obviously the result of the inducing and attracting +influence of the cloud upon the atmosphere near the surface of the earth +as it passes over it. Let the reader watch attentively this advance +condensation, from its eastern edge to the line of smooth cloud and +falling rain, and he will understand at a glance this internal action of +gust-clouds. The whole phenomena are simple and intelligible. A cloud +approaching from a westerly point, dark and irregular from its eastern +edge to the line of falling rain, where it appears smooth and of a light +color; wind from the east blowing gently toward it, till the condensation +is over us; then the gust following the cloud; then the rain, and in a few +minutes the cloud, and wind, and rain have passed on to the east, and +"sunshine" returns. + +The tornado, as it is termed when it occurs upon land, "spout," if on the +water, is sometimes of a different character, and as it undoubtedly had +great influence in inducing the gyrating theory of Mr. Redfield, and the +aspiratory theory of Mr. Espy, and has been cited by both in support of +their respective theories, it deserves a more particular notice. There are +several marked peculiarities attending it which determine its character. + +1st. It occurs during a _peculiarly sultry and electric_ state of the +trade and surface atmosphere, and at a time when thunder showers are +prevailing in and around the locality, and at every period of the year +when such a state of the atmosphere exists. One recently occurred in +Brandon, Ohio, in midwinter. + +2d. There is always a cloud above, but very near the earth, between which +and the earth the tornado forms and rages. It is usually described as a +black cloud, ranging about 1000 feet or less above the earth, often with +a whitish shaped cone projecting from it, and forming a connection with +the earth; at intervals rising and breaking the connection, and again +descending and renewing it with devastating energy. Its width at the +surface varies from forty to one hundred and eighty rods--the most usual +width being from sixty to ninety rods. Sometimes when still wider, they +have more the character of thunder-gusts, and are brightly luminous. + +3d. Two motions are usually visible, one ascending one near the earth and +in the middle, and a gyratory one around the other. The latter is rarely +felt, or its effects observed, near the earth. Occasionally, and at +intervals, objects are thrown obliquely backward by it. + +4th. It is composed, at the surface of the earth, of _two lateral +currents_, a northerly and southerly one, varying in direction, but +normally at right angles in most cases, although not always, with its +course of progression, extending from the extreme limits of its track to +the axis; which currents are most distinctly defined toward the center, +and upward. These currents prostrate trees, or elevate and remove every +thing in their way which is detached and movable. There does not seem to +be any current in advance of these lateral ones tending toward the +tornado, save in rare and excepted cases, and then owing to the make of +the ground or the irregular action of the currents; nor any following, +except that made by the curving of the lateral currents toward the center +of the spout as it moves on, and perhaps a tendency of the air to follow +and supply the place of that which has been carried upward and forward, +like that of water following the stern of a vessel. The south current is +always the strongest, and often a little in advance of the other, and +covers the greatest area. The proportion of the two currents to each other +is much the same that the S. E. trades bear to the N. E. This excess in +volume and strength of the southerly current will explain the +irregularities in most cases, and the fact that objects are so often +_taken up and carried from the south to the north side_, and so rarely +from the north and carried south of the axis. These irregularities are +such as attend all violent forces, and something can be found which will +favor almost any theory; but the two lateral currents appear always to be +the principal actors, except, perhaps, when it widens out and assumes more +the character of a straightforward gust. See a collection by Professor +Loomis, American Journal of Science, vol. xliii. p. 278. + +The following diagram is a section of the New Haven tornado, from +Professor Olmstead's map accompanying his article in the "American Journal +of Science and Art," vol. 37. p. 340. + +The manner in which the main currents flow is shown by their early and +unresisted effect in a cornfield, as represented by the dotted lines. The +direction in which the fragments of buildings were carried by the greater +power of the southerly currents is shown also. And so is this irregular +action, where a part of the southerly current broke through the northerly +one, and prostrated two or three trees backward on the north side of the +axis. + + +[Illustration: Fig. 16.] + + +5th. This cloud, and its spout, move generally with the course of the +counter-trade in the locality--_i. e._, from some point between S. W. and +W., to the eastward, but occasionally a little south of east, deflected by +the magnetic wave beneath the belt of showers. + +6th. Several exceedingly instructive particulars have been observed and +recorded. + +_a_. _No wind is felt outside of the track_, as those assert who have +stood very near it, and its effects show. + +_b_. The track is often as distinctly marked, where it passed through a +wood, as if the grubbers had been there with their axes to open a path for +a rail-road. The branches of the trees, projecting within its limits, are +found twisted and broken off, or stripped of their leaves, while not a +leaf is disturbed at the distance of a foot or two on the opposite side of +the tree, and outside of the track. + +_c_. As the spout passes over water, the latter seems to _boil up_ and +_rise to meet it_, and _flow up_ its trunk in a _continued stream_. + +_d_. As it passes over the land, and over buildings, fences, and other +movable things, they appear to _shoot up_, instantaneously, as it were, +into the air, and into fragments. If buildings are not destroyed or +removed, the doors may be burst open _on the leeward side_, and gable ends +_snatched out_, and roofs taken off on the _same side_, while that portion +of the building which is to the windward remains unaffected. + +_e_. Articles of clothing, and other light articles, have been carried out +of buildings through open doors, or chimneys, or holes made in the roofs, +and to a great distance, without _any opening_ being made for the air to +_blow_ in. + +_f_. If there be a discharge of electricity up the spout from the earth, +like that of lightning, the intense action ceases for a time or entirely. + +_g_. Vegetation in the track is often scorched and killed, and so of the +leaves on one side of a tree, which is within the track, while those on +the other side, and without the track remain unaffected. (Espy's +Philosophy of Storms, 359, cited from Peltier.) + +_h_. The active agent whatever it is, has been known to _seize hold of a +chain attached to a plow_ and _draw the plow about, turning the stiff sod +for a considerable distance_. (See Loomis on the tornado at Stow, Ohio, +American Journal of Science, vol. xxxiii. p. 368.) + +_i_. In passing over ponds, the spout has taken up all the water and fish, +and scattered them in every direction, and to a great distance. + +_j_. The barometer falls very little during the passage of the spout. (See +the Natchez hurricane of 1827, Espy page 337.) Not more than it +_frequently_ does during gentle showers. + +_k_. Persons have been taken up, carried some distance, and if not +projected against some object in the way, or some object against them, +have usually been _set down gently and uninjured_. + +_l_. Buildings which stood upon posts, with a free passage for the air +under them, although in the path of the tornado, escaped undisturbed. +(Olmstead's account of the New Haven tornado, American Journal of Science, +vol. xxxvii. p 340.) + +_m_. A chisel taken from a chest of tools, and stuck fast in the wall of +the house. (Ibid.) + +_n_. Fowls have had all their feathers stripped from them in an instant +and run about naked but uninjured.[5] + +_o_. Articles of furniture, etc., have been found torn in pieces by +antagonistic forces. + +_p_. Frames taken from looking-glasses without breaking the glass. Nails +drawn from the roofs of houses without disturbing the tiles. + +_q_. Hinges taken from doors--_mud taken from the bed of a stream_ (the +water being first removed), and let down on a house covering it +completely--a farmer taken up from his wagon and carried thirty rods, his +horses carried an equal distance in another direction, _the harness +stripped from them_, and the wagon carried off also, _one wheel not found +at all_. (American Journal of Science, vol. xxxvii. p. 93.) + +Pieces of timber, boards, and clapboard, driven into the side of a hill, +_as no force of powder could drive them, etc., etc._ + +Now to my mind, these circumstances indicate clearly, that it is not wind, +_i. e._, mere currents of air, which produces the effect, but that a +_continuous current_ or _stream of electricity_ from the earth to the +cloud exists, and carries with it from near the earth, such articles as +are movable: That this stream collects from the _northerly_ and +_southerly_ side upon the _magnetic meridian_, in _two currents_ with +_polarity_, which meet in their passage up at the center; curving toward +the center in the posterior part as the spout moves on, when acting in a +normal manner, and making the "_law of curvature_" observed: That no +conceivable movement of the air alone in such limited spaces could produce +such effects; or if so, that no agent but electricity could so move the +air: That the air in a building could not shoot the roof upward, and into +fragments; much less could the air in a cellar by any conceivable force, +be made to elevate _or shoot up_ the entire house, and its inmates, and +contents--effects so totally unlike what takes place in gales, +hurricanes, and typhoons: That elastic free air never did nor could take +hold of the plow chain, and plow up the ground; or scorch and kill the +vegetation; or twist the _limbs_ from one side of a tree, while the most +delicate leaves on the other, and within two or three feet, remained +unaffected and undisturbed; or pick the chickens: That even if the +expansion of the air could produce these effects--if a sudden vacuum were +produced--_nothing but currents of electricity could produce the sudden +vacuum_, by removing the air above. + +It is well settled that atmospheric electricity can and does flow in +currents with light, by experiments in relation to the brush discharge, +etc. That it may do so without light or disruptive discharge, and in a +stream, or as it is termed, by convection, with the force and effect seen +in the tornado, is perfectly consistent with what we know of it--and it +is, I think clearly evinced that such is the character of the phenomena, +by the fact that a sudden powerful _disruptive_ discharge, _with light, up +the spout_, produces an instantaneous partial or total suspension of its +action; to be renewed as the cloud passes over _another_ and more highly +charged _portion_ of the _earth's surface_. Peltier gives instances where +the spout has been entirely and instantaneously destroyed by such a sudden +and powerful discharge of electricity; marking the spot where it was so +destroyed by a large hole in the earth, from which the discharge issued. +And in fact these tornados are often steadily luminous, and so much so, +when they occur in the night, as to enable persons to read without +difficulty. + +The lateral inward and upward currents, are accompanied, after they meet +and unite, or seem to unite, by gyratory or circular ones. How are they +produced? This question can only be answered by analogy. No permanent +impressions are left by the circular currents, except to a limited extent, +and in occasional instances; and observation of them has been, and must +necessarily be limited and uncertain. I have witnessed one or two on a +moderate scale; but owing to the suddenness of their passage, and the +confusion of the objects taken up, it was difficult to determine what the +circular currents were. When the southerly current is much the strongest, +it appears sometimes to cross the axis, and curve round the northerly one. +Perhaps this may be all the curving that really takes place, except at the +posterior part of the axis, for evidence of a curving on the south of the +axis is rarely, if ever seen. + +Assuming, however, that the main currents unite and form one from the +earth to the cloud, _induced_ circular currents would be in perfect +keeping with the known laws of electricity. Such currents, and with +magnetic properties, are always induced by powerful currents of voltaic +electricity passing through wires. And doubtless _in all cases_ powerful +currents of electricity _induce attendant circular currents_. This may +account for the external gyration of the spout. + +Or it may be that the two lateral currents of air which attend the +currents of electricity, do not unite; having opposite polarity, but pass +by and around each other, in connection with the circular magnetic +currents. Future observation and perhaps experimental research will +determine this. But it may not be accomplished by the present generation; +for the belief that tornados are mere whirlwinds, produced by the action +of the sun in heating the land, is adhered to, notwithstanding they cross +the intense magnetic area of Ohio in mid-winter, and seems to be +ineradicable. + +The proportions of different winds vary in different localities. For the +benefit of those who are curious, I copy a table from an able compilation +by Professor Coffin, published by the Smithsonian Institute, showing the +proportion of the winds at New Haven (the station nearest to me). It will +be noticed that during the year the N. W. winds blow the greatest number +of days; the S. W. next; the N. E. and S. E. less than either, and about +equal. It may be observed that the two latter bear about the same +proportion to the whole, that our number of cloudy and stormy days, +averaging about ninety, bear to the whole number of days in the year. + + +------------------------------------------------+ + |Course.| 1804. | 1811. | 1812. | 1813. | Total. | + |------------------------------------------------| + | N. | 143 | 105 | 90 | 111 | 449 | + | N. E. | 99 | 207 | 138 | 138 | 582 | + | E. | 33 | 18 | 22 | 23 | 96 | + | S. E. | 131 | 108 | 135 | 110 | 484 | + | S. | 58 | 69 | 113 | 80 | 320 | + | S. W. | 224 | 255 | 153 | 261 | 893 | + | W. | 81 | 69 | 102 | 57 | 309 | + | N. W. | 329 | 264 | 345 | 315 | 1253 | + +------------------------------------------------+ + +This work of Mr. Coffin has been brought to my notice since the foregoing +pages were written. The facts embodied in it will be found to comport with +what I have observed and stated. In relation to the proportionate number +of days in the year during which the wind blows from the different points +of the compass at the several stations it is very full and able. + +But it has cardinal defects. It does not show the _main currents_ of the +atmosphere. It treats the surface-winds, which are incidental, as +principals. The direction of the main currents is indeed shown frequently +by the mean course of the surface winds, but not uniformly or +intelligibly. Nor does it distinguish between the fair weather and storm +winds; nor always between the trade winds during their northern transit, +and the variable winds north of the trade-wind region. Hence, the +deductions derived from it disclose no general system, and sustain no +theory, although many very important facts appear. Some of these, +Professor Coffin found it difficult to reconcile with received theories, +or satisfactorily explain. For instance, he found the prevailing winds of +the United States, in Louisiana and Texas, S. and S. E.; in western +Arkansas, and Missouri, southerly, and in Iowa and Wisconsin, S. W., +forming a curve, and evidently connected together. + +Thus, alluding to the winds west of the Mississippi, and between the +parallels of 36 deg. and 60 deg., he says: + + "On the American continent, west of the Mississippi, there appears to + be more diversity in the mean direction of the wind, yet here it is + westerly at sixteen stations out of twenty, from which observations + have been obtained. The most peculiar feature in this region, is the + _line_ of southerly winds on the western borders of Arkansas and + Missouri. It seems to form a connecting link between the winds of + this zone and the south-easterly ones that we find south of it; and, + in some degree, to favor an idea that has been advanced, that there + is a vast eddy, extending from the western shore of the Gulf of + Mexico, to the eastern shore of the Atlantic; that the easterly + trade-winds of the Atlantic Ocean, when they strike the American + continent, veer northwardly, and then N. E., and thus recross the + Atlantic, and follow down the coast of Portugal and Africa, till they + complete the circuit." + +This mean prevalence of the curving winds indicates the course of the +western portion of the concentrated counter-trade, of which we have so +fully spoken, and to which that portion owes its rains and fertility. +Doubtless the curve would have been traced somewhat further west, if +observations had been obtained from more westerly stations. + +The idea of an eddy, to which Professor Coffin alludes, is of course +unsound; that of a counter-trade, most fully confirmed; the curve +corresponding with that of the regular rains and fertility as they are +known to exist. + +Professor Coffin is a believer in the generally-received theory of +rarefaction, as the cause of all winds. His work is published by the +Smithsonian Institution, and the theory is, so far forth, nationalized. +But he found it very difficult to reconcile all the facts he obtained, +with the theory, and, possessing a truth-loving mind, he frankly admits +it. Alluding to the prevalence of N. E. winds off the coast of Africa in +the summer months, as shown by certain numbered wind-roses, he says: + + "Nos. 81, 83, 86, and 91, have caused me much perplexity. The arrows + for the warmer months evidently indicate a point of rarefaction + situated to the _south_ or _south-west_, and yet all the observations + from which they were computed were taken within a few hundred miles + of the African coast and desert of Sahara; a region, the annual range + of whose temperature must be exceedingly great. The only way in which + I can account for a fact so astonishing, is, by supposing the + deflecting forces at these numbers to be secondary to the influence + which we see so strongly marked in Nos. 88, 89, and 90. Let us, then, + first devote our attention to these." + +(We have not space for the map of Professor Coffin, nor is it necessary to +insert it. The numbers 81, 83, 86, and 91, refer to respective portions of +the Atlantic, west of Africa, North of the Cape de Verdes, of 5 deg. of +latitude each, where the N. E. trades are drawing off from the coast. The +Nos. 88, 89, and 90 refer to like portions _below_ the Cape de Verde, +where the S. W. monsoons are found under the rainy belt; and the +explanation of the distinguished author is an attempt to account for the +blowing of the trades _from_ Sahara, by supposing them connected with the +monsoons further south, which seem to blow toward it.) + + "The intense heat of the Great Desert rarefies the air exceedingly + from June to October, inclusive, and hence the arrows of unparalleled + length (Plate XII.)," (showing the monsoon winds below the Cape de + Verdes,) "pointing toward it during those months, the longest being + longer than that which represents the most uniform of the + trade-winds, in the ratio of 104 to 89. The influence of this + rarefaction is sufficient to curve the powerful current of the + trade-winds in the manner exhibited on Plate VII. Nos. 89 and 90, and + to produce the not less remarkable change in No. 88, holding the + current back and retarding it, so that its progressive motion in the + _three_ months of July, August, and September united, hardly exceeds + that during any _one_ of the colder months of the year. But while + this is so, the trades on the western side of the Atlantic are + pursuing nearly their regular track, being but slightly affected by + these influences. As a consequence, the latter must leave, as it + were, a partial vacuum behind them, which is filled by air flowing in + from the north-east and south-east. This will account for the seeming + anomaly of having a somewhat strong deflecting force directed toward + mid-ocean, in the hottest part of the year, as in the numbers above + referred to. _And yet it may be very naturally asked, Why does not + the air from these parts supply the Great Desert directly, instead of + taking a circuitous route to supply the region that supplies it? A + question which, I confess, it seems difficult to answer._" + +(The italicization in the foregoing extract is mine). + +Here the worthy professor finds a fact inconsistent with the theory of +rarefaction--viz.: that the winds blow off shore, and toward mid-ocean, +opposite Sahara, and he is "perplexed and astonished." The theory, +however, must be maintained, and one of those modifying hypotheses which +have made meteorology such a complicated piece of patch-work, must be +invented; some "deflecting forces" found. There is the Great Desert, +bordering upon the ocean, north of the Cape de Verde Islands, for a +distance of six hundred miles, widening as it extends inland, whose +temperature, as he says, "_must be exceedingly great_;" and doubtless is +so, and yet the air, instead of blowing in upon it in a hurricane, is +actually drawing off from it, and blowing towards the S. W., where the +water and air do not rise above 84 deg.. Well may he be "perplexed and +astonished." + +Turning south, however, to the distance of five hundred miles or more, he +finds the S. W. monsoon winds, which in those months blow under the belt +of rains, toward the land, in the direction of, but at a great distance +from, Sahara. It is an easy matter to suppose that they reach the Great +Desert and supply its vortex of rarefaction, inasmuch as they blow in a +direction toward it, and distance is no impediment to supposition. + +Then it is necessary to _suppose_ that the S. E. and N. E. trades, at the +south-west, draw so strongly to the westward as to create a partial vacuum +to the S. W. of Sahara, which is filled by the winds which draw off shore, +and then we have the supply brought from the distance of five hundred +miles or more, by an ascending vortex, which creates a vacuum, and the air +near the vortex taken away in _another_ direction by a _partial_ vacuum; +and so an ascending _vortex_, which creates a vacuum is supplied from a +distance, and a _partial vacuum_ at a distance is supplied by the air near +the perfect vacuum. Such an idea of a supply by a circuitous route, and +secondary influence, is not very philosophical, to say the least, and +Professor Coffin feels it; and to the question, Why is it so? which, he +says, may very naturally be asked, he confesses there is no answer. And +there would be none, even if his suppositions were based upon facts. But +other questions might be asked equally difficult to be answered, viz.: + +1st. Is there any rarefaction which can draw the trades to the west, and +in that particular locality, in opposition to the supposed vortex of +Sahara, by creating a _partial vacuum_? + +2d. Are they in fact so drawn? + +3d. Do the S. W. winds, south of the Cape de Verdes, and _under the rainy +belt_, which in the summer months extend up to these islands, _reach the +desert at all_? + +These are pertinent questions, _and every one of them must be answered in +the negative_. The hypothesis is without foundation, and Professor's +Coffin's perplexity and astonishment must remain, until he abandons the +theory of rarefaction entirely. The winds which so perplex him are nothing +but the regular N. E. trades, made to originate on the coast and continent +of Africa, in summer, by the northern transit of the whole machinery. They +not only draw off from the desert coast, but they _blow over the desert +itself_ on to the ocean, and into the rainy belt upon the land, as we have +already seen, and the supposed vortex of rarefaction does not exist. + +That the monsoons do not reach the desert is demonstrated by the tables of +Professor Coffin, and to set it at rest we will make the necessary +extracts. Commencing with the region from the equator to 5 deg. N., and from +10 deg. to 55 deg. W. longitude, we have the observed winds in proportion, as +follows, for July and August--the south-east trades prevailing, inasmuch +as the belt of rains is at this season situated further north. + +LATITUDE 0 deg. TO 5 deg., LONGITUDE FROM GREENWICH 10 deg. TO 55 deg.. + + +-------------------------------------------------------+ + | Course. | July. | August. | Course. | July. | August. | + |-------------------------------------------------------| + | North. | 0 | 0 | S. S. W.| 54 | 111 | + | N. N. E.| 8 | 2 | S. W. | 1 | 29 | + | N. E. | 6 | 2 | W. S. W.| 6 | 19 | + | E. N. E.| 27 | 16 | West. | 2 | 9 | + | East. | 31 | 20 | W. N. W.| 1 | 6 | + | E. S. E.| 120 | 96 | N. W. | 1 | 0 | + | S. E. | 216 | 276 | N. N. W.| 0 | 2 | + | S. S. E.| 218 | 443 | Calm. | 8 | 4 | + | South. | 69 | 279 |---------------------------| + | | | | Total | 768 | 1,314 | + +-------------------------------------------------------+ + +Here, it is evident that the S. E. trades are the prevailing winds, but +their course is variable. + +Ascending to the region between 5 deg. and 10 deg. north latitude, and 10 deg. to 55 deg. +west longitude, the northern part of which at this season is covered by +the rainy belt; we find the monsoon, the S., S. S. W., and S. W. winds, +the prevailing ones in August, although the winds are variable, as usual +under the rainy belt. + + +-------------------------------------------------------+ + | Course. | July. | August. | Course. | July. | August. | + |-------------------------------------------------------| + | North. | 19 | 6 | S. S. W.| 188 | 368 | + | N. N. E.| 26 | 11 | S. W. | 63 | 94 | + | N. E. | 104 | 32 | W. S. W.| 73 | 93 | + | E. N. E.| 30 | 16 | West. | 33 | 48 | + | East. | 45 | 29 | W. N. W.| 30 | 18 | + | E. S. E.| 36 | 40 | N. W. | 21 | 9 | + | S. E. | 93 | 53 | N. N. W.| 17 | 13 | + | S. S. E.| 225 | 307 | Calm. | 109 | 74 | + | South. | 239 | 514 |---------|-------|---------| + | | | | Total | 1,351 | 1,725 | + +-------------------------------------------------------+ + +Ascending to the region of 10 deg. to 15 deg. north latitude, and 15 deg. to 45 deg. west +longitude, we find the winds exceedingly variable, and the monsoons +diminished remarkably. If Professor Coffin's theory was correct, they +should increase as they approach the desert; but they in fact, diminish, +and the N. E. trades are found at the north portion. + + +-------------------------------------------------------+ + | Course. | July. | August. | Course. | July. | August. | + |-------------------------------------------------------| + | North. | 17 | 55 | S. S. W.| 30 | 71 | + | N. N. E.| 64 | 74 | S. W. | 33 | 63 | + | N. E. | 155 | 149 | W. S. W.| 19 | 43 | + | E. N. E.| 91 | 71 | West. | 12 | 25 | + | East. | 83 | 60 | W. N. W.| 17 | 21 | + | E. S. E.| 25 | 26 | N. W. | 13 | 24 | + | S. E. | 17 | 26 | N. N. W.| 24 | 56 | + | S. S. E.| 13 | 33 | Calm. | 62 | 78 | + | South. | 9 | 44 |---------|-------|---------| + | | | | Total | 684 | 919 | + +-------------------------------------------------------+ + +Ascending to the region between 15 deg. and 20 deg. north latitude, and 15 deg. to 45 deg. +west longitude, we get north of the belt of rains _and lose the monsoons +entirely although still below the desert_; and find the regular N. E. +trades, with less variable winds than are found in almost any other part +of the ocean. + + +-------------------------------------------------------+ + | Course. | July. | August. | Course. | July. | August. | + |-------------------------------------------------------| + | North. | 39 | 20 | S. S. W.| 0 | 5 | + | N. N. E.| 210 | 185 | S. W. | 0 | 5 | + | N. E. | 112 | 87 | W. S. W.| 8 | 3 | + | E. N. E.| 114 | 104 | West. | 0 | 1 | + | East. | 20 | 36 | W. N. W.| 0 | 4 | + | E. S. E.| 21 | 17 | N. W. | 3 | 4 | + | S. E. | 0 | 2 | N. N. W.| 3 | 31 | + | S. S. E.| 2 | 11 | Calm | 20 | 8 | + | South. | 5 | 1 |---------|-------|---------| + | | | | Total, | 557 | 526 | + +-------------------------------------------------------+ + +Ascending still further to the region between 20 deg. and 25 deg. north latitude, +and 15 deg. and 45 deg. west longitude, which borders, in part, on the S. W. +corner of the desert, and we have not, during the month of August, a +single wind between S. S. E. and W. N. W., which blows in upon the land; +and _only twelve instances out of three hundred and ninety-four in this +hottest month in the year, and on the southern portion of the desert, when +the wind blows on shore from any quarter_. This is demonstration. The +monsoon winds are confined to the rainy belt; they do not reach the +desert, nor does the desert attract the winds from the ocean, or +reverse, hold back, or disturb the trades. + + +-------------------------------------------------------+ + | Course. | July. | August. | Course. | July. | August. | + |-------------------------------------------------------| + | North. | 25 | 20 | S. S. W.| 3 | 0 | + | N. N. E.| 210 | 153 | S. W. | 2 | 0 | + | N. E. | 129 | 77 | W. S. W.| 13 | 0 | + | E. N. E.| 110 | 86 | West. | 0 | 0 | + | East. | 8 | 20 | W. N. W.| 0 | 3 | + | E. S. E.| 4 | 11 | N. W. | 2 | 1 | + | S. E. | 0 | 3 | N. N. W.| 5 | 8 | + | S. S. E.| 1 | 7 | Calm. | 2 | 5 | + | South. | 1 | 0 |---------|-------|---------| + | | | | Total, | 515 | 394 | + +-------------------------------------------------------+ + +Ascending once more, to the region between the degrees of 25 and 30, north +latitude, and 15 and 45, west longitude, we find it bounded east entirely +on the center of the desert. Now here, certainly, there must be evidence +of the truth of the rarefaction theory, if any where on the face of the +earth. Yet here, in July and August, we find the trades as regular as any +where, and not more variable winds than are found in the trades toward +their northern limits every where, and in August, only forty out of four +hundred and twenty-nine winds, blowing directly or indirectly on shore. + + +-------------------------------------------------------+ + | Course. | July. | August. | Course. | July. | August. | + |-------------------------------------------------------| + | North. | 32 | 19 | S. S. W.| 9 | 6 | + | N. N. E.| 155 | 125 | S. W. | 3 | 9 | + | N. E. | 144 | 35 | W. S. W.| 13 | 14 | + | E. N. E.| 140 | 89 | West. | 12 | 3 | + | East. | 48 | 57 | W. N. W.| 7 | 7 | + | E. S. E.| 31 | 23 | N. W. | 11 | 1 | + | S. E. | 8 | 7 | N. N. W.| 36 | 6 | + | S. S. E.| 8 | 12 | Calm. | 18 | 12 | + | South. | 5 | 4 |---------|-------|---------| + | | | | Total, | 680 | 429 | + +-------------------------------------------------------+ + +It would seem to be impossible for any man to believe in the theory of +rarefaction, after an examination of these tables. + +Professor Coffin discovers other anomalies, for which he finds it +difficult to account. Among these are the northerly tendency, in the +afternoon, of the winds in Ohio, south of Lake Erie; the winds of +south-western Asia, which, he says, "Are so irregular as to defy all +attempts to reduce them to system;" particularizing the N. W. at +Jerusalem, the westerly at Bagdad, the N. E. at Constantinople, the +northerly at Trebizond, etc., etc. Jerusalem has the Mediterranean at the +N. W., Bagdad has it at the west, Constantinople has the Black Sea at the +N. E., Trebizond N. N. W. and N. E., and the counter-trade, as it passes +over them, draws its storm-surface wind or sea-breeze, from the quarter +where evaporation is greatest, and the atmosphere is most susceptible of +electrical inductive influence. Precisely as it draws from the ocean and +the eastward, east of the Alleghanies, from the lake region, west of the +lakes, and from the northward, south of the lakes, and from the westward, +east of them. + +This law of attraction will explain, too, the mean prevalence of easterly +winds north of the parallel of 60 deg., at the stations named in his work. +Great Bear Lake, Great Slave Lake, and Fort Enterprise, lie east of the +Rocky Mountain range which interposes between them and the Pacific, and +have Hudson's Bay and other large bodies of water on the east and north. +Hence, easterly winds prevail at these places. At Norway House, on +Nelson's River, near the north end of Lake Winnipeg, a large body of +water, which stretches off to the south, we find the south wind the +prevalent one, especially in December, when the northern and north-eastern +waters are frozen up, and the N. E. largely present at all seasons of the +year. + +At New Hernhut, in winter, when Davis' Straits are covered with floes, the +prevailing wind is east, drawn from the warm, open sea east of Greenland, +where the Gulf Stream is evaporating. But in June and July, when +evaporation is going on over Davis' Straits and Baffin's Bay, the +prevailing winds are west and south, and the east winds fall off. + +Other stations are equally instructive, but I must forbear. + +In relation, however, to the easterly zone of wind, of which Professor +Coffin speaks, it should be added that the counter-trade, south of the +magnetic pole, in high latitudes, pursues an easterly course, is near the +earth, and attracts an opposite wind as it does on the east and north of +the pole, in localities where the surface atmosphere is not peculiarly +susceptible to its influence, and, therefore, the _winds are mainly +opposite to its course_. Thus, at Melville Island, they are almost all +westerly and north-westerly, for there the remnant of the counter-trade is +passing west around the magnetic pole. These westerly and north-westerly +winds are very light, and like the gentle easterly breeze which sets +toward the cumulus clouds and summer showers. + +Since most of this work was written, I have procured, and read with great +pleasure, Lieutenant Maury's "Geography of the Sea." It is a work of +great interest, and should be in the hands of every one. The extent of +ground covered, however, made it necessary for Lieutenant Maury to +introduce much matter not derived from his own investigations. In doing +this, he has taken received opinions, and has thereby introduced much +heresy. The view he adopts in relation to the monsoons, although the +popular one with philosophers, is of that character. He says (page 222): + + "Monsoons are, for the most part, formed of trade-winds. When a + trade-wind is turned back, or diverted, by over-heated districts, + from its regular course at stated seasons of the year, it is regarded + as a monsoon. Thus, the African monsoons of the Atlantic, the + monsoons of the Gulf of Mexico, and the Central American monsoons of + the Pacific, are, for the most part, formed of the north-east + trade-winds, which are turned back to restore the equilibrium which + the over-heated plains of Africa, Utah, Texas, and New Mexico have + disturbed. When the monsoons prevail for five months at a time--for + it takes about a month for them to change and become settled--then + both they and the trade-winds, of which they are formed, are called + monsoons." + +Again (Sec. 476-7): + + "The agents which produce monsoons reside on the land. These winds + are caused by the rarefaction of the air over large districts of + country situated on the polar edge, or near the polar edge, of the + trade-winds. Thus, the monsoons of the Indian Ocean are caused by the + intense heat which the rays of a cloudless sun produce, during the + summer time, upon the Desert of Cobi and the burning plains of + Central Asia. When the sun is north of the equator, the force of his + rays, beating down upon these wide and thirsty plains, is such as to + cause the vast superincumbent body of air to expand and ascend. There + is, consequently, a rush of air, especially from toward the equator, + to restore the equilibrium; and, in this case, the force which tends + to draw the north-east trade-winds back becomes greater than the + force which is acting to propel them forward. Consequently, they obey + the stronger power, turn back, and become the famous south-west + monsoons of the Indian Ocean, which blow from May to September + inclusive. + + "Of course, the vast plains of Asia are not brought up to monsoon + heat _per saltum_, or in a day. They require time both to be heated + up to this point and to be cooled down again. Hence, there is a + conflict for a few weeks about the change of the monsoon, when + neither the trade wind nor the monsoon force has fairly lost or + gained the ascendency. This debatable period amounts to about a month + at each change. So that the monsoons of the Indian Ocean prevail + really for about five months each way, viz.: from May to September, + from the south-west, in obedience to the influence of the over-heated + plains, and from November to March inclusive from the north-east, in + obedience to the trade-wind force." + +What the "trade-wind force" is, Lieutenant Maury tells us in another +paragraph, viz.: "Calorific action of the sun and diurnal rotation of the +earth"--the received calorific theory. I have already shown, I think, +conclusively, that there is no expansion and ascent in the supposed region +of calms, which induces, or can induce, the trades; and that, in point of +fact, the air on the land is cooler under the belt of rains. But as +Lieutenant Maury, whose reputation is national, adopts the theory, I shall +be pardoned for copying the following table, showing the difference of +temperature at two cities of India, before, after, and while the belt of +inter-tropical rains is over them. It will be seen that the temperature is +actually less when the belt is there, viz., in July and August, than in +April and May. _This should be conclusive upon that point._ + + +----------------------------------------------------+ + | | Anjarakandy. | Calcutta. | + | Months. |--------------------|-------------------| + | | Rain. | Temp. | Rain. | Temp. | + |-----------|----------|---------|---------|---------| + | | M. M. | | M. M.| | + | January, | 2,26 | 26 deg.,5 | 0,0 | 18 deg.,4 | + | February, | 2,26 | 27 deg.,7 | 67,68 | 21 deg.,5 | + | March, | 6,77 | 28 deg.,4 | 24,82 | 25 deg.,6 | + | April, | 29,33 | 29 deg.,8 | 130,84 | 28 deg.,5 | + | May, | 175,96 | 28 deg.,6 | 16,24 | 29 deg.,7 | + | June, | 794,05 | 26 deg.,6 | 575,24 | 29 deg.,3 | + | July, | 807,59 | 25 deg.,8 | 338,38 | 28, deg.1 | + | August, | 572,98 | 26 deg.,0 | 311,31 | 28 deg.,3 | + | September,| 311,31 | 26 deg.,4 | 254,91 | 28 deg.,0 | + | October, | 157,91 | 26 deg.,8 | 42,86 | 27 deg.,2 | + | November, | 65,42 | 26 deg.,9 | 20,30 | 23 deg.,0 | + | December, | 29,33 | 26 deg.,5 | 0,0 | 19 deg.,2 | + |-----------|----------|---------|---------|---------| + | Year, | 2955,14 | 27 deg.,2 | 1928,74 | 26 deg.,4 | + +----------------------------------------------------+ + +Anjarakandy is on the Malabar coast, between 12 deg. and 13 deg. north latitude. +Calcutta in an angle of the Bay of Bengal, at 22 deg. 30' north latitude. The +former is in and near the focus of the monsoons, and has a temperature in +July (when 18 inches of rain fall), about as low as in December. + +In the foregoing table from Kaemptz, the rain is in millimetres, about +twenty-five of which make an inch, and the temperature is centigrade, +which may be raised to Fahrenheit by adding four fifths of the quantity +and also 32 deg.--thus, if the height of the centigrade thermometer be 25 deg., +add to this four fifths of 25 deg., which is 20 deg., and also 32 deg., the result is +77 deg.. Twenty-five centigrade is therefore equal to seventy-seven +Fahrenheit. + +Lieutenant Maury is not, and should not be a theorist. He occupies the +position, in some sort, of a national _investigator_, and, of course, of +national _instructor_. Opinions which emanate from him, or which are +endorsed by him, should be accurate. Sooner or later that which he has +adopted in relation to the monsoons, and some others, must be abandoned. +In addition to what has already been said, I wish to call his, and the +reader's attention, to several other facts and considerations in relation +to the monsoons, and particularly those of India. + +1st. The deserts of Cobi and Bucharia, which constitute the "burning +plains" of _Central_ Asia, north-east of the Indian Ocean, lie between 38 deg. +and 45 deg. of north latitude, and under the zone of extra-tropical rains. +They are not wholly rainless. They partake of that saline character which +affects so much of Asia and the western part of this continent. South of +them, running nearly east and west, are the lofty ranges of the Himmalaya +and Kuenlun Mountains, and the table lands of Thibet. To their saline +character, in part, but mainly to the interposition of these mountain +ranges, depriving the counter-trade of moisture, they owe their +comparative sterility. _If bountifully supplied with rains, this salt +would doubtless ere this have been washed to the ocean, as it has been +from other countries, once as salt as they._ But they have some rain, and +more or less vegetation, and are not intensely hot. They lie too far +north, and are too elevated. Their temperature is not materially different +from that of the western, and comparatively desert portions of our own +country, and they are utterly incapable of creating a monsoon at the +Indian Ocean, and especially from the long line of Malabar coast, where +the south-west monsoons are found in most strength. The sterile portions +of Utah, New Mexico, and Texas are alike incapable of such effect upon the +atmosphere of Central America and Mexico. These monsoons commence in May, +and prevail until October, and the temperature of the air where they blow +ranges with considerable regularity between 76 deg. at night, and 84 deg. at +mid-day, on the Malabar coast, and a trifle lower in Central America. + + At Fort Fillmore, El Paso, New Mexico, in latitude 32 deg.03, the mean + temperature for + + May is 68 deg. + June " 78 deg., 5' + July " 80 deg., 1' + August " 83 deg., 8' + September " 77 deg., 9' + ------- + And for the whole period, 77 deg., 1' + + At Santa Fe, New Mexico, the mean for + May is 66 deg., 9' + June " 72 deg., 5' + July " 75 deg., 3' + August " 72 deg., 9' + September " 62 deg., 3' + ------- + And for the whole period, 69 deg., 3' + + Mean of the two united, 73 deg., 2' + +The mean of Western Texas is about 2 deg. higher than at Fort Fillmore, and of +Utah not materially different; and the mean of _Central_ Asia between 38 deg. +and 45 deg. does not materially vary from them. + +Now, it is perfectly evident that during May and September the temperature +of Central Asia is far below that of the Indian Ocean and India, and never +materially exceeds it. Central Asia is hot, "burning," if you please, +compared with more elevated, fertile, or better watered territory _in the +same latitude_, and so it has been characterized; but not so, compared +with the Indian Ocean, or India, where the sun is vertical. During the +greater part of the time, therefore, that the monsoons are in full blast, +Utah, Texas, and New Mexico, and Cobi, and the burning plains of Asia, are +from 5 deg. to 10 deg. colder than the temperature of the place where the monsoons +are blowing. Would not such a fact be perfectly conclusive in any other +science except theory-swathed meteorology? + +2d. The theory assumes that the heated air has an ascensive force, which +causes it to rise and create a vacuum, and this vacuum, by its suction, +draws in the adjoining air, which immediately ascends. The adjoining air, +drawn away from its locality, leaves a vacuum, and that is filled by +another rush from the S. W., and so on, till the Indian Ocean is reached, +and the monsoons are accounted for. + +Now, look at the difficulties: + +The highest temperature that can be assumed for the air over Cobi, at any +time, without disregarding facts and analogy, is 100 deg.. What is the +ascensive power of an area of atmosphere of 100 deg.? For this we have no +problem or formula, although problems and formulas abound in the science. +Professor Espy relied on heated air only to give the storm a _start_. His +main reliance was on the latent heat supposed to be given out during +condensation, for his ascensive storm power. But over these "burning +plains" there is, according to the theory, no storm or cloud, or +condensation on which that supposed reliance for expansion can be placed. +What, then, is the ascension force of air at 100 deg.? _We ought to know, for +we sometimes have it as high, or within two or three degrees as high, in +all the eastern and middle States._ + +The monsoons blow at from twenty to twenty-five miles an hour, and +sometimes more. Is that the ascensive force of air at 100 deg.? At 25 miles an +hour it would be 2,200 feet; at 20 miles, 1,760 feet; and at 10 miles, 880 +feet per minute. + +Does any man believe that either current exists? Why, then, do we not have +our hats taken off, or light objects carried up, or have a monsoon, or, at +least, have the clouds running up, when we have such elevated +temperatures. _Nothing of the kind occurs with us._ Our hottest days are +comparatively still days; and I have seen the cumulus sailing gently to +the east, horizontally, when the air was at 98 deg.. Why should we be exempt? +Is not our air the same and our heat the same? + +Again, suppose we grant that the ascensive force is equal to 20 or even 10 +miles an hour, will not the adjoining air hold back somewhat to avoid +leaving behind an entire vacuum? or, will it all voluntarily rush in, and +leave a new complete vacuum? and, if so, why the preference of vacuums by +the air, and _when, where, and why_, should the _successive vacuums stop_? +Nay, would not gravity fill the second vacuum from _above_, rather than +from the south-west side? and will not the air incline to rush in, to some +or all these successive vacuums, from some other side than south-west? or, +have these deserts the power of selecting the quarter from which their +vacuum shall be filled, and of delegating it to succeeding vacuums? Would +it not incline to rush in from the east and west where there are no +elevations, rather than from the S. W. and over the Kuenlun Mountains, the +intervening ridges and valleys of Thibet, the lofty Himmalayas, the extent +of India, and the Ghaut Mountains, from three to four thousand feet high, +on its eastern coast? Would it not, at least, _leak in a little_, and +lessen the force with which the vacuums would draw from the far-off Indian +Ocean, so that the monsoon could not blow with equal force? or, if Cobi +and its fellow deserts _must_ and _can_ draw from an _ocean_, why not from +the head of the Arabian Sea, or Bay of Bengal, or the China Sea, which are +nearer, or from the Japan Sea, which is still nearer, or the Yellow Sea, +which is close by? Why draw only from under the central belt of rains? +Nay, what shall be done with Professor Dove? In a recent article, +republished in the American Journal of Science and Art, for January, 1855, +he says: "A greatly diminished atmospheric pressure taking place in summer +over the _whole continent_ of Asia must produce an influx from all +surrounding parts; and thus we have west winds in Europe, north winds in +the Icy Sea, east winds on the east coast of Asia, and south winds in +India. _The monsoon itself becomes, as we see, in this point of view, only +a secondary phenomena._" This looks very like _antagonism_. Who shall we +believe? + +Again, suppose you get one atmosphere from the whole area, raised up by +the supposed ascensive force, and at the rate of twenty-five, twenty, or +even ten miles an hour, and a new volume drawn in from the south-west, +and _over the mountains_: will it not take a _little time_ for _that_ to +_heat up_? Does it heat so fast as to _keep up the ascensive force_ +without intermission, at twenty-five, or twenty, or ten miles the hour? +What says Mr. Ericsson to this? Can he not arrange with a moderate lens, +to move his engine with the rays of the summer sun? Nay, Lieutenant Maury +says they can not heat up "_per saltum_, or in a day." But according to a +reasonable calculation, they must heat up the air from 80 deg., or less, to +100 deg., at the rate of 2,000 feet per minute. Heating 2,000 feet in depth, +in the proportion of 20 deg. per minute, night and day, for five months, is +"_per saltum_" in a minute, and 1,440 "_saltums_" per day! + +And further still, the Indian Ocean, from which the monsoons are drawn to +Cobi and Central Asia to the N. E., is during those months covered by the +belt of calms and rains, as heretofore stated; and the S. E. trades +blowing into it are attributed to the suction created by the ascent of +heated air _there_. So, then, the monsoons are blowing away from under the +rainy belt, from 500 to 1000 miles, to Cobi and the burning plains of +Asia, while the ascensive force of that belt is such as to draw the S. E. +trades toward the very spot, a distance of 1,200 or 1,500 miles, at 20 +miles an hour! What must the ascensive force over Cobi, etc., be, if, as a +"stronger power," it can overcome an ascensive force over the Indian Ocean +sufficient to draw the S. E. trades 1,500 miles, at 20 miles an hour; and, +in addition to the force necessary to resist this central suction, not +only stop or hold back the N. E. trade, but reverse it and draw it back, +at 20 miles an hour, as a monsoon? Must it not be, at least, double that +of the belt of calms, or the "great region of expansion," as Professor +Dove calls it? + +Now, I am irresistibly tempted to ask whether a meteorological theory can +be too absurd for credence, and whether it would not be as well to endow +the deserts with ribs and lungs, and a proboscis long enough to reach the +Indian Ocean, and the necessary power of inspiration and expiration? Such +a theory would avoid all difficulties, conflict with no more analogies, +and, in my judgment, be as much entitled to credit as the one to which +meteorologists adhere. + +3d. North of the Malabar coast, in the north-west of India, lies an +extensive desert. West of that is Beloochistan, with its rainless deserts. +Further west are the rainless deserts of Arabia, and these three, +including the Persian deserts further north, cover _as much surface_ as +the deserts of Cobi and Bucharia--have the sun vertical in part, and +nearly so over the entire surface--_are more intensely hot_, and lie +within _one third of the distance_ which intervenes between that desert +and the Indian Ocean off the Malabar coast, with _an open sea and_ no +_mountains between_. Now, look at it. The north-west desert of India, and +the rainless deserts of Beloochistan and Arabia _reverse no trade_ and +_have no monsoon_, although the Arabian Sea heads right up among them. +They do not attract one from the Indian Ocean off the Malabar coast, +although not more than one third of the distance off, and without such +mountains and table lands intervening as separate that coast from Cobi. It +is said by Lieutenant Maury that the monsoons, "_obey the stronger +force_." But which is the stronger force? Cobi, not _wholly_ rainless, +lying north of 35 deg., under the zone of extra-tropical rains, with India and +the Ghauts, the Himmalaya Mountains, the table lands of Thibet, and the +Kuenlun Mountains between? or the deserts of India, Beloochistan, and +Arabia, _wholly rainless_, and _intensely hot, near by_, and in _open +view_. There can be but one answer to this question. Nothing in the way of +desert barrenness, or elevated temperature, unless it be those of Sahara, +can exceed the deserts about the head of the Arabian Sea and Persian Gulf. +Certainly those of Cobi can not compare with them; yet the trades blow +steadily over them, although more northerly there, as every where, near +their northern limits, especially on land. Says Hopkins, in his +atmospheric changes: + + "If any one part of the broad expanse of the continent of Asia could + be heated so as to draw air from the Arabian Sea and the Indian Ocean + during the summer, it would be that part which lies between + Hindoostan and the Lake of Aral, including the region between the + Valley of the Oxus and Persia, and the land of this part, unlike + Hindoostan, is not screened from the sun by thick vapors. But what + says Burnes respecting the winds of this part? Why, that about the + latter end of June, though the thermometer was at 103 deg. in the day, + 'In this country a steady wind generally blows from the north.' And + on the 23d of August, after having passed the Oxus--'The heat of the + sand rose to 150 deg., and that of the atmosphere exceeded 100 deg., but the + wind blew steadily, nor do I believe that it would be possible to + traverse this tract in summer if it ceased to blow. The steady manner + in which it comes from one direction is remarkable in this inland + country.' Again--'The air itself was not disturbed but by the usual + north wind that blows steadily in this desert.' And he has many other + similar passages." + +Here there is a vast tract of country south of 35 deg. which has a temperature +often of 103 deg., and does not reverse the trade and create a monsoon. How +utterly unphilosophical, then, to attribute the monsoons to Cobi because +they "obey the stronger force!" or to attribute them to it at all. + +4th. The monsoons can not be _traced from_ the Malabar coast _to Cobi_. +They do not exist on the south-west of Cobi and near it, where they should +in greatest force, and there is no connection, in fact, shown between +them. They do not often extend more than twenty-five miles inland, or to +the east of the Ghauts. There are no corresponding intervening monsoons +crossing India to the mountains--none over the mountains and table +lands--none under the northern lee of the mountains--nor, in short, on the +whole track, nor any S. W. winds except such as naturally belong to the +action of the curving counter-trade. + +Finally, the investigations of Commodore Wilkes on Mauna Loa, a mountain +upon Hawaii, more than 13,000 feet high, and the observations of Professor +Wise and other aeronauts are sufficient to put this whole matter of heated +lands and ascent of the atmosphere as the cause of winds, at rest. +Commodore Wilkes was encamped for about _twenty days_ on Pendulum Peak, in +December and January 1840. Although not up to the elevation of the +counter-trade in that latitude, he was above the local clouds which form +over the island during the day, where the sea breezes blow in with as +great strength as any where. Indeed, he was on the top of the "lofty +conical mountain" to which Caleb Williams alludes in the letter to +Professor Espy I have quoted, and above the spot where Professor Espy +assumed that the clouds were rising with such force as to induce the +strong sea breezes of that island. During this time there were two +snow-storms on Mauna Loa, and they had the wind from the S. W. during the +storm, as might be expected, looking at the situation of the mountain on +the western side of the island. These storms moved to the N. W., and were +observed at the other islands in that direction as rain. + +The local clouds lay over the island every day, as they do over active +volcanic islands which are very elevated, although it was the dry season. +_Nothing like an ascent of the clouds or of the currents of air from the +ocean was observed._ On the contrary, the clouds formed before the sea +breezes set in, and the latter blew from the different sides of the island +in under the clouds, and outward again, probably on the opposite side. The +whole interior of the island is elevated, and its temperature low; and +_there was no elevation of temperature on the high portions of the island +over which the clouds formed, and toward which the winds blew, which could +create an upward current_. + + "During our stay on the summit, we took much pleasure and interest in + watching the various movements of the clouds; this day in particular, + they attracted our attention; the whole island beneath us was + covered with a dense white mass, in the center of which was the cloud + of the volcano rising like an immense dome. All was motionless until + the hour arrived when the sea-breeze set in from the different sides + of the island; a motion was then seen in the clouds, at the opposite + extremities, both of which seemed apparently moving toward the same + center, in undulations, until they became quite compact, and so + contracted in space as to enable us to see a well defined horizon; at + the same time there was a wind from the mountain, at right angles, + that was affecting the mass, and drawing it asunder in the opposite + direction. The play of these masses was at times in circular orbits, + as they became influenced alternately by the different forces, until + the whole was passing to and from the center in every direction, + assuming every variety of form, shape and motion. + + "On other days clouds would approach us from the S. W. when we had a + strong N. E. trade-wind blowing, coming up with cumulus front, + reaching the height of about eight thousand feet, spreading + horizontally, and then dissipating. At times they would be seen lying + over the island in large horizontal sheets as white as the purest + snow, with a sky above of the deepest azure blue that fancy can + depict. I saw nothing in it approaching to blackness at any time." + (Exploring Expedition, vol iv. p. 155). + +Here, in the last paragraph, we have the whole truth disclosed. The N. E. +trade was blowing on Mauna Loa, 13,000 feet above the sea, and the +sea-breeze blew in on the _leeward side_, its moisture condensing over the +volcanic island, but without rising _up the mountain_, or _through the +surface-trade_, or _above 8,000 feet_. + +So, too, the celebrated aeronaut, Mr. Wise, in the course of more than a +hundred ascensions, some during high wind, and others during rain storms, +never met with an ascending current, except in a single instance, in the +body of a hail-cloud, and then there were descending currents also, the +usual intestine motion of hail-cloud with its opposite polarities. + +I copy a description of his passage through the clouds of a rain-storm, +and his floating a long period above them; and there was no ascending +current which disturbed their horizontal repose or progression. The double +layer is not uncommon--condensation taking place at the connection of the +upper and lower portions of the trades, with the surrounding atmosphere; +or in the trade, and by _induction in the surface atmosphere_ at the same +time. Such instances are frequently visible, and if his ascensions had +been undertaken at other times in stormy weather he would have seen more +of them. + + "Before I passed the limits of the borough, a parachute, containing + an animal, was dropped, which descended fast and steady, and, just as + it reached the earth, my aerial ship entered a dense black body of + clouds. Ten minutes were consumed in penetrating this dismal ocean of + rainy vapor, occasionally meeting with great chasms, ravines, and + defiles, of different shades of light and darkness. When I emerged + from this ocean of clouds, a new and wonderfully magnificent scene + greeted my eyes. A faint sunshine shed its warmth and luster over the + surface of this vast cloud sea. The balloon rose more rapidly after + it got above it. Viewing it from an elevation above the surface, I + discovered it to present the same shape of the earth beneath, + developing mountains and valleys, corresponding to those on the + earth's surface. The profile of the cloud-surface was more depressed + than that on the earth, and, in the distance of the cloud-valley a + magnificent sight presented itself. Pyramids and castles, rocks and + reefs, icebergs and ships, towers and domes--every thing belonging to + the grand and magnificent could be seen in this distant harbor; the + half-obscured sun shedding his mellow light upon it, gave it a rich + and dazzling luster. They were really "castles in the air," formed of + the clouds. Casting my eyes upward, I was astonished in beholding + another cloud-stratum, far above the lower one; it was what is + commonly termed a "mackerel sky," the sun faintly shining through it. + The balloon seemed to be stationary; the clouds above and below + appeared to be quiescent; the air castles, in the distance, stood to + their places; silence reigned supreme; it was solemnly sublime. + Solitary and alone in a mansion of the skies, my very soul swelled + with emotion; I had no companion to pour out my feelings to. Great + God, what a scene of grandeur! Such were my thoughts; a reverence for + the works of nature, an admiration indescribable. The solemn + grandeur--the very stillness that surrounded me--seemed to make a + sound of praise. + + "This was a scene such that I never beheld one before or after + exactly like it. Two perfect layers of clouds, one not a mile above + the earth; the other, about a mile higher; and, between the two, a + clear atmosphere, in the midst of which the balloon stood quietly in + space. It was, indeed, a strange sight--a meteorological fact, which + we cannot possibly see or make ourselves acquainted with, without + soaring above the surface of the earth." (History and Practice of + Aeronautics, p. 209). + +This is graphic. Perhaps in relation to the conformity of the upper +surface of the inferior layer of clouds, to the irregularities of the +earth's surface, he was misled during the enthusiasm of the moment. He is +certainly mistaken as to the possibility of observing these double layers +from the earth; I have seen them in hundreds of instances. But in relation +to the _quiescence_ of the clouds for an hour, and _the entire absence of +ascending currents_, he could not be mistaken. + +And now, in the absence of all direct proof to sustain the hypothesis, +that the heating of the land produces ascending currents, and thereby the +winds, and especially the monsoons, and in view of all the adverse +evidence, I put it to Lieutenant Maury, and every sincere searcher after +meteorological truth, whether the theory should not be abandoned. + + + + +CHAPTER VII. + + +The counter-trade of the northern hemisphere ranges at different heights +in different latitudes, in the same latitude at different seasons, and +also upon different days of the same season; and, like the line of +perpetual snow, has its greatest elevation in the tropics, descending +gradually to the surface of the ocean at the poles. At the northern limit +of the N. E. trades, it does not, ordinarily, approach the earth +sufficiently near for decided reciprocal action. Hence, at that point, +storms do not often originate; the winds are lighter and more variable, +and calms are more frequent than at any point, except at the meeting and +elevation of the trades, or in the polar regions. Doubtless this state of +things is increased by the feebler action of north polar magnetism, and +the irregular action of the longitudinal magnetic currents, evinced by the +irregular, and often, feeble action of the trades, near their extreme +limits. They are not unfrequently wholly wanting, near the northern limit, +for several days in succession, and calms and baffling winds are found in +their place--another effect of the irregular action of terrestrial +magnetism, consequent upon the ever-changing transit of central activity +from south to north, and from north to south. Upon the islands, however, +and continents, which have elevated mountain peaks and ridges, especially +if of volcanic origin and activity, which approach more nearly the path of +the counter-trade, a different state of things exists. There, showers and +gusts are frequent. Thus, upon the Sandwich Island, Kauai, the most +northern one, which is within the region of the N. E. trade during ten +months of the year, and upon its volcanic peaks and elevated table-lands, +and north-easterly from them, over the district of Waioli, rain falls in +abundance during the year, while the coastlines upon other portions of the +island can not be cultivated without irrigation. (See Wilkes' Exploring +Expedition, vol. iv. pp. 61 and 71; and American Journal of Science and +Art, for May, 1847). + +A like state of things, in degree, may be found upon the Canaries, and the +more elevated of the West India Islands. The Cape de Verdes are an +exception, and the Christian world are quite often called upon for +contributions of provisions, to save the inhabitants of these islands from +starvation. They lie at the northern limit of the equatorial belt, and for +a period of two months only (July and August), are supplied with rain. If, +from any cause, the belt does not move as far north as usual during any +season, unbroken drought and famine are sure to overtake them. The islands +contain some elevated peaks, and are of volcanic origin, but not of +present volcanic activity, and the counter-trades as they issue from the +equatorial belt at their highest elevation, are too far above them for +reciprocal, influential action. If the islands could be placed 10 deg. further +north, we should hear no more of drought or famine from them, and their +quantity of rain and fertility would be not only more permanent, but much +increased. Superadded to this, is the fact, that at that point the belt of +rains precipitates feebly because the S. E. trade originates upon the +southern part of the continent of Africa, and the N. E. mainly, upon the +desert and the Barbary States--and both are sparingly supplied with +moisture. + +The same state of things is strikingly obvious upon continents wherever +the mountains are sufficiently elevated, even within the trade-wind +region. Thus, in South America, the Andean ranges are of great elevation, +and spurs and table-lands extend from them a considerable distance to the +eastward. There, the S. E. and N. E. trades of the Atlantic meet in very +considerable volumes, and not only is the equatorial belt much wider than +upon the Atlantic and Pacific, but the counter-trades are met upon the +elevated peaks and mountain-ranges, and showers and storms on their +eastern slopes and summits are frequent during the dry season--down even +to the extra-tropical belt. I have already said that it was probable that +the great elevation of the Andes diverted and turned south a portion of +the N. E. counter-trade which would otherwise pass over the western coast +of Peru. + +The report of Lieutenant Herndon, which has come to my notice since that +was written, states facts which strongly corroborate that opinion. It +seems that the trades and counter-trades actually _bank up_, in their +passage to the westward, against those mountains, and the true elevation +of their eastern slopes can not be barometrically ascertained. (See report +of the Exploration of the Amazon, p. 261). Lieutenant Herndon says: + + "I was surprised to find the temperature of boiling water at Egas to + be but 208 deg. 2', the same within 2' of a degree that it was at a point + one day's journey below Tingo Maria, which village is several hundred + miles above the last rapids of the Huallaga river; at Santa Cruz, two + days above the mouth of the Huallaga, it was 211 deg. 2'; at Nauta, three + hundred and five miles below this, it was 211 deg. 3'; at Pebas, one + hundred and seventy miles below Nauta, 211 deg. 1'. I was so much + surprised at these results that I had put the apparatus away, + thinking that its indications were valueless; but I was still more + surprised, upon making the experiment at Egas, to find that the + temperature of the boiling water had fallen 3 deg. below what it was at + Santa Cruz, thus giving to Egas an altitude of fifteen hundred feet + above that village, which is situated more than a thousand miles up + stream of it. I continued my observations from Egas downward, and + found a regular increase in the temperature of the boiling water + until our arrival at Para, where it was 211 deg. 5'. + + "From an after-investigation, I am led to believe that the cause of + this phenomenon arises from the fact that the trade-winds are dammed + up by the Andes, and that the atmosphere in those parts is, from this + cause, compressed, and, consequently, heavier than it is further from + the mountains, though over a less elevated portion of the earth. The + discovery of this fact has led me to place little reliance in the + indications of the barometer for elevation, at the eastern foot of + the Andes. It is reasonable, however, to suppose that this cause + would no longer operate at Egas, nearly one thousand miles below the + mouth of the Huallaga." + +The report of Lieutenant Gibbon, is also exceedingly instructive. +Separating from Lieutenant Herndon at Tarma, upon the Andes, he pursued a +southern course, along the eastern slopes of the chain from 11 deg. 30' +south, almost to 18 deg. south, at Ohuro, making a journey of about 7 deg. 30' of +latitude. + +A considerable portion of this journey was over eastern and less elevated +portions of the Andes; but little below, however, the line of perpetual +snow. Here, during the dry season, he met with frequent showers and fogs +from the eastward, but left them as he descended into the plains upon the +table-land. There he found the dry season more distinctly marked; but +occasional irregularities were found upon the table-lands, as every where +upon corresponding elevations. The S. E. trades, however, were there +obvious, during the dry season, notwithstanding the irregularities. The +rainy season, from December to May, he spent at Cochabamba, and at its +close he traveled north down the Madeira and its tributaries, to the +Amazon. Although scarcely consistent with my prescribed limits, I can not +forbear making a few extracts. Thus, when on the mountains, east of +Huanvelica, in the N. E. counter-trade, he says: + + "Our course is to the eastward. The snow-capped mountains are in + sight to the west. Temperature of a spring 48 deg.; air 44 deg.. Lightning + flashes all around us; as the wind whirls from _north-east_ to + south-west, rain and snow-flakes become hail, half the size of peas. + Thunder roars and echoes through the mountains; the mules hang their + heads, and travel slowly; the thinly-clad aboriginal walks shivering + as he drives the train ahead; the dark cumulus cloud seems to wrap + itself around us." + +Again, at the Bombam Post-house, in the focus of change from cirrus to +cumulus, and stratus, and storm: + + "The winds are very gentle, and curl the cirrus or hairy clouds in + most graceful shapes about the hoary-headed Andes, in rich and + delicate clusters; when the peak is concealed, all but the blue tinge + below the snow, we see a natural bridal vail. An _easterly wind_ + lifts and turns them to dark, cumulus clouds, settled on the frosty + crown, like an old man's winter cap; the physiognomical expression is + that of anger. The change is accompanied by thunder, and seems to + command all around to clothe themselves for storms. The cold rain + comes down in _fine drops_ upon us; the day grows darker, and the + _clouds press close upon the earth_." + +During an excursion east of Cuzco-- + + "Turning from the river, we ascend a steep ridge of mountains--the + eastern range at last. A heavy mist _wafts upward as the winds drive + it against the side of the Andes_, so that our view is shortened to a + few hundred yards. We hope the curtain will rise that we may view the + productions of the tropical valley below; but the mist thickens, and + the day gets dark with heavy, heaped-up black clouds; a rain-storm + follows. The grasses are thrifty, and the top of the ridge covered + with a thick sod. By barometer, we stand eleven thousand one hundred + feet above the level of the sea." + +In May following, having spent the rainy season in Cochabamba, he travels +north-- + + "Our route from Tarma to Oruro was south. We traveled ahead of the + sun. In December, when we arrived in Cochabamba, the sun had just + passed us. As soon as he did so, the rains descended heavily on this + side of the ridge; it was impossible to proceed. The roads were + flooded, the ravines impassable, and the arrieros put off their + journey until the dry season had commenced. After the sun passed the + zenith of Cochabamba, and had fairly moved the rain belt after him + toward the north, then we came out from under shelter, and are now + walking behind the rain belt in dry weather, while the inhabitants + are actively employed in tending their crops." + +So on the north of the equatorial belt, along the whole line of the Andes, +up to the northern boundary of the desert valley of the Gila, rain falls +on the high mountain-ranges, owing to the contiguity of the counter-trade +and the diversion of showers to the north, along their eastern sides. + +During the survey of the boundary line between Mexico and California, +etc., by the commission under Mr. Bartlett, it became necessary to find +some spot where water and grass were abundant, for the head quarters of +the commission. This was found, and _could only be found_, upon the +Mimbres Mountains, at an old abandoned Spanish copper mine, 7,000 or 8,000 +feet above the level of the sea, surrounded with peaks of still greater +height. These elevated ranges were within influential distance of the +counter-trade, and here snow fell in the winter, from the extra-tropical +belt, and rain, in showers, in summer, at the period of the most northerly +extension of the tropical belt; when fifteen miles off, in the valley, it +was unbroken drought. Mr. Bartlett thus describes it in his Personal +Narrative: + + "We reached this district on the 2d of May. Vegetation was then + forward, though there had been no rain. But it must be remembered + that during the winter there is snow, and hence a good deal of + moisture in the earth when the spring opens. The months of May and + June were moderately warm. On the third of July the first rain fell. + It then came in torrents, accompanied by hail, and lasted three or + four hours. Many of our adobe houses were deluged with water, and the + mountain-sides exhibited cataracts in every direction. The Arroyo, + which passes through the village, and which furnishes barely water + enough for our party and the animals, became so much swollen as to + render it difficult to cross; and, by the time it had received the + numerous mountain torrents, which fall into it within a mile from our + camp, it became impassable for wagons, or even mules. The dry gullies + became rapid streams, five or six feet deep, and sometimes fifty feet + or more across. On this day, a party, in coming to the copper mines, + from the plain below, _where there had been no rain_, found + themselves suddenly in a region overflowing with water, so that + their progress was arrested, and they were obliged to wait until the + flood had subsided. After this we had occasional showers, during the + months of July and August." + +The location of this mountain station is near the thirty-third degree of +north latitude, while the northern limit of the equatorial belt, nowhere, +except upon the mountain ranges and table-lands of Mexico, extends above +25 deg.. + +There, for the reason we have been considering, it does extend further +north during July and August, in occasional showers, and in the vicinity +of Mount Picacho, Mr. Bartlett met one of its mountain thunder-storms on +the 13th of July, on his return south through Mexico, in latitude 32 deg., in +the following year. (Personal Narrative, vol. ii. p. 285). These showers +originated in strata of counter-trade, which had followed up along the +eastern side of the mountains and not from strata which had crossed them +and curved to the eastward, as is shown by the course of progression of +the showers. + +Let us look, in this connection, at a fact or two of great interest, +though not directly connected with the point in hand. The southern limit +of the extra-tropical belt in winter, on the Pacific coast of North +America, is in the vicinity of San Diego, at about 32 deg.. In summer, that +limit is carried up above Astoria, which is in latitude 46 deg. 11'--about +14 deg.--yet New Mexico receives little if any rain in winter in the vicinity +of Albuquerque, but does receive a limited supply of about seven inches in +summer and autumn, five and a half inches of which falls in June, July, +and August. Albuquerque is in latitude 35 deg. 13', below the southern summer +limit of the extra-tropical belt, and north of the northern limit of the +equatorial belt. This anomaly is explained by the extension west over +northern New Mexico, of the extreme western edge of our concentrated +counter-trade, by reason of its issuing further west from the equatorial +belt in its northern extension in the summer months. This western edge, in +curving to the east, north-east of New Mexico, covers the north-western +States, Iowa, Minnesota, Wisconsin, etc., and furnishes them that great +excess of summer precipitation which is a peculiarity of their climate; +and its absence further east in winter, and the very great elevation of +the Rocky Mountains and other ranges over which their ordinary +counter-trade of that season curves, account for the absence of much +precipitation and snow there, or over the valley of the Rio Grande in New +Mexico, in winter. + +We may now see, too, why the western coast and the Pacific region of the +continent, below 45 deg., are so deficient in moisture. The S. E. trades, +which arise from the western portion of the south Atlantic and the +continent of South America, which, if it were not for the Andes chain, in +their natural course, after passing the equatorial belt, would continue on +to the north-west until they passed the limits of the N. E. trades, and +curve in upon the western portion of our continent below 45 deg., and supply +it bountifully with rain, are, in part, perhaps, diverted along the +eastern side of those mountains to swell the volume of our counter-trade, +and in part pass them, almost exhausted of their supply of moisture by +their contiguous reciprocal action. Hence, too, the deficiency of +precipitation at the base of the Andes, on the western side, and the +peculiar and irregular character of the winds under the western lee of the +Andean range. Baffling airs and bands of calms prevail on this portion of +the Pacific, except where the mountains fall off, and then there is a +westerly or south-westerly monsoon under the equatorial belt. Says +Lieutenant Maury in his Charts, sixth edition, p. 731: + + "The passage, under canvass, from Panama to California, as at present + made, is the most tedious, uncertain, and vexatious that is known to + navigators. + + "My investigations have been carried far enough to show that at + certain seasons of the year a vessel bound from Panama to California, + must cross at least three, at some seasons four, such meetings of + winds or bands of calms, before she can enter the region of the N. E. + trades. Hence the tedious passage." + +Such will ever be the state of things on this continent and upon the +eastern Pacific, so long as the S. E. counter-trades are compelled to pass +over the mountain chain of South and Central America. + +Again, if we examine carefully the belt or zone of extra-tropical rains, +we shall find that the focus of greatest precipitation is considerably +north of its southern limit, and that, other things being equal, this +focus travels north in summer, and gives to higher latitudes their needed +summer rains. This is very apparent upon the north-western portion of our +continent, as the following table will show: + + +----------------------------------------------------------- + | | Lat. |Jan.|Feb.|Mar.|Apr.|May.|June.| + | |-------|----|----|----|----|----|-----| + |San Diego, Cal. |32 deg. 41'| 0.3| 1.7| 1.1| 0.9| 0.5| 0.0 | + |San Francisco. |37 deg. 48'| 1.7| 0.5| 4.4| 2.1| 0.4| 0.0 | + |Cant., Far W., Cal.|39 deg. 02'| 3.3| 0.6| 6.4| 2.2| 0.9| 0.0 | + |Astoria, Oregon. |46 deg. 11'|27.0|10.9| 6.1| 4.4| 5.9| 2.6 | + |Puget's S'd, Ore. |47 deg. 07'|11.8| 3.9| 4.7| 4.1| 0.8| 0.6 | + |Sitka, Russ. Am. |57 deg. 3'| 2.5| 9.6| 3.5| 3.3| 1.9| 5.9 | + +----------------------------------------------------------- + + ---------------------------------------+ + |July.|Aug.|Sept.|Oct.| Nov.|Dec.|Year.| + |-----|----|-----|----|-----|----|-----| + | 0.0 | 0.2| 0.0 | 0.1| 1.5 | 3.4| 9.6| + | 0.0 | 0.0| 0.4 | 0.6| 3.0 | 5.5| 18.8| + | 0.0 | 0.0| 0.3 | 0.1| 3.5 | 4.6| 21.9| + | 0.0 | 2.3| 1.9 | 6.7|13.2 | 6.2| 87.2| + | 0.5 | 1.3| 1.6 | 3.6| 5.9 | 6.1| 44.8| + | 3.7 |10.1|14.8 |12.7| 7.4 | 4.2| 79.5| + ---------------------------------------+ + + The figures are for inches and tenths of an inch of rain. + +Thus, it will be seen that in January, when the southern line is at San +Diego, at the south line of California, the focus of precipitation is over +Oregon; and that in August and September when the southern line is carried +up and over Oregon, the focus has traveled north to Sitka, and that it is +always at least 10 deg. north of the southern line of the belt upon that +coast. The increased quantities of rain which fall at the focus of +precipitation there, from Oregon up, are doubtless much enhanced by the +equatorial oceanic current which flows over opposite that part of the +continent. A like effect, precisely, is produced in Europe. The quantity +of rain which falls at Bergen, in Norway, being 87-61/100 inches per year, +more than three times the average for that continent. + +The difference shown in the foregoing table, between Astoria and Puget's +Sound, is owing to the fact that the latter lies in the interior and +within the coast range of mountains, while Astoria is situated at the +mouth of the Columbia River, with an open view of the ocean. + +A like comparative increase of precipitation in northern latitudes, in +summer, is found every where varying according to the local influences +which operate in the particular case. Thus, + + ------------------------------------------------------------------------ + There falls in |Winter.|Spring.|Summer.|Aut'mn.| Year. + ---------------------------------|-------|-------|-------|-------|------ + Burlington, Vt., lat. 44 deg. 20' | 5.7 | 7.3 | 11.4 | 9.8 | 33.9 + Albany, N. Y., lat. 42 deg. 39' | 8.3 | 9.8 | 12.3 | 10.3 | 40.7 + Minnesota, Iowa, lat. 41 deg. 28' | 7.3 | 12.3 | 17.4 | 11.7 | 48.8 + St. Peters'g, Russ., lat. 59 deg. 56'| 3.89 | 3.20 | 5.70 | 4.71 | 17.51 + Pekin, China, lat. 40 deg. | .54 | 3.35 | 18.80 | 2.29 | 25.68 + ------------------------------------------------------------------------ + +Pekin lies in the northern part of China, and would have a much larger +fall of rain from a concentrated counter-trade, but for the numerous +mountain-ranges which intersect its path in winter, but over which it +passes at a greater elevation during the summer--a peculiarity from which +the eastern section of this country is most remarkably and happily free. + +Thus, it is obvious that the focus of precipitation in the zone of extra +tropical rains, is some 8 deg. to 12 deg. north of its southern line, and travels +with the whole machinery in its annual transit north and south. + +It is a question of some difficulty, perhaps, whether this focus is +increased by the increase of magnetic action at this point, for both the +line of descent of the counter-trade, and the focus of magnetic action, +are carried up in a like manner, and for a like cause, and, in all +probability, both concur in the result. + +There is exceeding wisdom in this provision for the gradual subsidence of +the counter-trade, and gradual increase of magnetic intensity, and +consequent gradual precipitation. On the European continent, and over +western Asia, there are 50 deg. of latitude to be supplied with moisture by +this polar belt of rains. If the focus of precipitation was at its +southern border, the counter-trade would be deprived of its moisture at +that point, and little would reach the more northern portions of the globe +which are to be supplied by it. But the movement of the whole machinery +carries up the southern line from the south boundaries of the Barbary +States on to the Mediterranean and portions of southern Europe, and the +focus of precipitation and of near approach of the counter-trade to the +earth, being situated far north of the southern line, is carried up +correspondingly, while the combination of the moisture with the atmosphere +by south polar magnetism and electricity, and the gradual descent of the +counter-trade, enable it to resist, to some extent, the influence of north +polar magnetism and cold, and thus retain portions of its moisture for +distribution in the polar regions. + +_The elevation of the counter-trade above the earth varies in the same +latitude with the variations in the phenomena of the weather._ An +attentive observation of the clouds of our climate will soon satisfy any +one of this, after he has become familiar with them, so as to distinguish +with certainty the clouds of the trade. Its range, in this country, is +from 3,000 feet, or less, to 12,000 feet above the earth, and its depth +with us probably, from 6,000 to 8,000 feet. Gay-Lussac, in his scientific +experimental balloon ascension, the first of _that character_ ever made, +except an imperfect one just previous, by himself and Biot, found it at +about 12,000 feet over Paris, and about 4,000 feet in depth. It is +detected by the thermometer when much elevated. + +The atmosphere grows cool as it is ascended on mountains, or by balloons. +The rate of cooling is ordinarily about 1 deg. of Fahrenheit for every 300 +feet. If it were not for the equatorial current, this progressive decrease +of temperature would doubtless be perfectly uniform. Of Gay-Lussac's +ascension, on this point it was said: + + "At forty minutes after 9 o'clock, on the morning of the 15th + September, 1804, the scientific voyager ascended, as before, from the + garden of the repository of models. The barometer then stood at 30.66 + English inches, the thermometer at 82 deg. Fahrenheit, and the hygrometer + at 57-1/2 deg.. The sky was unclouded, but misty. + + "During the whole of this gradual ascent, he noticed, at short + intervals, the state of the barometer, the thermometer, and the + hygrometer. Of these observations, amounting in all to twenty-one, he + has given a tabular view. We regret, however, that he has neglected + to mark the times at which they were made, since the results appear + to have been very materially modified by the progress of the day. It + would likewise have been desirable to have compared them with a + register, noted every half hour, at the Observatory. From the surface + of the earth to the height of 12,125 feet, the temperature of the + atmosphere decreased regularly, from 82 deg. to 47 deg. 3' by Fahrenheit's + scale; _but afterward it increased again, and reached to 53 deg. 6' at + the altitude of 14,000 feet_; evidently owing to the influence of the + warm currents of air which, as the day advanced, rose continually + from the heated ground. From that point the temperature diminished, + with only slight deviations from a perfect regularity. At the height + of 18,636 feet the thermometer subsided to 32 deg. 9', on the verge of + congelation; but it sunk to 14 deg. 9' at the enormous altitude of 22,912 + feet above Paris, or 23,040 feet above the level of the sea, the + utmost limit of the balloon's ascent." + +The high range of the barometer indicated a very considerable elevation +of the trade at the time Gay-Lussac made his ascension. I am not aware +that it has since been found at so great an elevation, in so high a +latitude, though it is undoubtedly elevated by the interposition of a +large volume of N. W. air, upon some occasions, to nearly the same +altitude with us. + +In the extract in relation to the ascension of Gay-Lussac, we have another +of the thousand hastily-adopted and absurd hypotheses connected with the +caloric theory. It is obviously and utterly _impossible_ that in addition +to the ordinary accumulation of heat at the surface of the earth "_as the +day advanced_"--that is, _during the forenoon_, warm currents should +ascend, unobserved by Gay-Lussac during an ascent of 12,000 feet--not +_affecting in the least_ so large an intervening body of the atmosphere or +his thermometer, and in such immense volumes as to increase the warmth of +a stratum of 4,000 feet in depth, an average of 3 deg. of Fahrenheit, and to +the extent of 6 deg. at the center. + +Very few balloon ascensions have been made with a view to scientific and +accurate observation. But other aeronauts have met the counter-trade at +different altitudes, and in both clear and stormy weather. + +Recently, in 1852, four ascensions were made in England, under the +direction of the Kew Observatory Committee, of the British Association. I +copy from the August number of the "London, Edinburg, and Dublin +Magazine," for 1853, the following condensed amount of the result: + + "The ascents took place on August 17th, August 26th, October 21st, + and November 10th, 1852, from the Vauxhall Gardens, with Mr. C. + Green's large balloon. + + "The principal results of the observations may be briefly stated as + follows: + + "Each of the four series of observations shows that the progress of + the temperature is not regular at all heights, but that at a certain + height (_varying on different days_) the regular diminution becomes + arrested, and for the space of about 2,000 feet the temperature + remains constant, or even increases by a small amount. It afterward + resumes its downward course, continuing, for the most part, to + diminish regularly throughout the remainder of the height observed. + There is thus, in the curves representing the progression of + temperature with height, an appearance of _dislocation_, always in + the same direction, but varying in amount from 7 deg. to 12 deg.. + + "In the first two series, viz.: August 17th and 26th, this peculiar + interruption of the progress of temperature is strikingly coincident + with a _large_ and _rapid fall_ in the temperature of the + _dew-point_. The same is exhibited in a less marked manner on + November 10th. On October 21st a dense cloud existed at a height of + about 3,000 feet; the temperature decreased uniformly from the earth + up to the _lower_ surface of the cloud. When a slight rise commenced, + the rise continuing through the cloud, and to about 600 feet above + its upper surface, when the regular descending progression was + resumed. At a short distance above the cloud, the dew-point fell + considerably, but the rate of diminution of temperature does not + appear to have been affected in this instance in the same manner as + in the other series; the phenomenon so strikingly shown in the other + three cases being perhaps modified by the existence of moisture in a + _condensed_ or vesicular form. + + "It would appear, on the whole, that about the principal plane of + condensation heat is developed in the atmosphere, which has the + effect of raising the temperature of the higher air above what it + would have been had the rate of decrease continued uniformly from the + earth upward." + +These gentlemen do not adopt the absurd explanation of the French +philosophers; they account for the phenomenon by supposing heat to be +_developed_ at that particular part of the atmosphere; but they are +equally wide of the mark. They found the excess of heat there to the +extent of 7 deg. to 12 deg., and on days when there was no condensation, or other +assignable cause for its _development_. + +The temperature of the counter-trade partakes, doubtless, of the +temperature of the adjoining strata at its upper and lower portion, and +has never been found much, if any, higher than 60 deg. at the center. Nor +could it be expected. The trade, in its upward curving course, within the +tropics, attains a considerable altitude where the atmosphere is +comparatively cold, and necessarily loses a portion of its heat there, and +during its northern flow. Probably its central summer range, in the +latitude of Paris, is not far from 55 deg., and with us 60 deg.. + +The contrast between the trade and the surrounding atmosphere, in winter, +is much more striking, and this has been observed particularly upon the +Brocken of the Alps, and in the polar regions. + +"In all seasons the temperature is higher on the Brocken, on a serene, +than on a cloudy day, and, in the month of January, _the serene days were +warmer than at Berlin_." (Kaemtz's Meteorology, by Walker, p. 217.--Note.) + +As the portion of the counter-trade, which does not become depolarized--in +diminished volume--progresses toward the polar regions, it settles nearer +the earth, and within the Arctic circle is found but little way above it. +Thus, in December, 1821, Parry, at Winter Island, in latitude 66 deg. 11', +flew a kite, with a thermometer attached, to the height of 379 feet, and +found that the temperature, instead of falling 1-1/4 deg., the usual ratio of +decrease, rose 3/4 of a degree. + +The same thing was observed at Spitzbergen, in latitude 77 deg. 30' north, and +at Bosekop, latitude 69 deg. 58', by a scientific commission, and by means of +kites, confined balloons, and the ascent of elevations. + + "In winter the temperature goes on increasing with the height, up to + a certain limit, which is variable, according to the different + atmospheric circumstances, the influence of which is not yet very + exactly known. The hour of the day appears to be indifferent, since + there exists no thermometric diurnal variation in the strata of the + surface. The mean of thirty-six experiments, made with kites, or with + captive balloons, at Bosekop, latitude 69 deg. 58' north, has given a + mean rate of increase of 1 deg. 6' for the first hundred meters.[6] + Beyond this limit, and even beyond the first 60 or 80 meters, the + temperature again becomes decreasing, at first very slowly, but + afterward the decrease is accelerated. The observations that have + been made on the flanks, or on the summits, of mountains, during the + same expeditions, entirely confirm these results. The cooling + influence of a soil, that radiates its own heat for several weeks, + without receiving any thing on the part of the sun, in compensation + of its losses, the influence of _counter-currents from above_, coming + from the west and the south-west, with a high temperature, account + for this anomaly, which, in winter, represents the normal state of + the most northern parts of the European continent." (Walker's Kaemtz, + p. 515.--Note.) + +Mr. Walker is the only author, so far as I know, who has suspected the +true cause of the phenomenon, viz.: "currents from above coming from the +west and south-west, with a high temperature;" but the caloric theory +"sticks like a burr," and he adheres also to the idea that a snow-clad +surface, in the absence of the sun, can aid, by radiation, in warming the +atmosphere for a distance of several hundred yards above it, increasing +the warmth as the distance from the earth increases! + +This contrast between the counter-trade and the adjacent atmosphere, in +winter, in latitudes as low as that of the Brocken, is probably heightened +by the increased warmth of the former, at that season. The S. E. trades +then form under a vertical sun, and the difference of temperature can not +be less than from 6 deg. to 8 deg.. Not unfrequently in winter and spring the rain +will fall with a temperature of 50 deg. to 55 deg., when the atmosphere near the +earth is 10 deg. or 20 deg. or more, below those points; and it is frozen to every +object upon which it falls. The trade stratum, from which it descends, is +not warmed by "radiation" or by ascending currents from a snow-clad +surface, and during a cloudy day; nor by a "development of heat" at that +particular altitude, but it has brought its heat from the South Atlantic, +and imparts it to the rain which forms within it. There is every reason to +believe that the counter-trade flows north in a regular descending plane, +not materially differing from that of the line of perpetual snow. The +descent of the latter is well ascertained to be from about 16,000 feet at +the equator, to _the surface_ at the poles. The plane of the counter-trade +is probably much the same, varying over different localities, from the +varied action between it and the earth which we are considering; and +probably both correspond with the increase of magnetic intensity. + +Lieutenant Maury, in an able and original article upon the circulation of +the atmosphere, conceives the bands of comparative calms at the northern +limits of the trades, which he appropriately terms the "_Calms of +Cancer_," to be nodes in the circulation of the atmosphere, and that the +upper or counter-trade here decends and becomes a surface wind from the S. +W., as the N. E. trade is a surface wind; and that an upper current from +the poles approaches and descends at the same node, to make the N. E. +trade. But it is evident he adopted that conclusion too hastily, as he +obviously did the conclusion that the calms of the horse latitudes were a +type of all. We have seen that the latter are increased by a diversion of +the counter-trade, and that they are avoided by making easting. So it may +be observed that our upper current is a S. W. current, and no northerly +upper current is visible, or exists over the country, however it may be in +western Europe and the North Pacific, on the west of the magnetic poles, +where cold, dry northerly and north-easterly winds are found. The origin +and progress of storms withal demonstrates that no such node can exist. + +Two points have been made in relation to the course of the counter-trade +in the tropics, and are relied upon to show its progress there to the N. +E., which deserve consideration. + +In the first place, it is well known that "rain dust" falls in +considerable quantities on the western coast of Africa, particularly about +the Cape de Verde Islands, and also upon the Mediterranean and +south-western Europe, where it is termed "sirocco dust." + + "This dust," says Lieutenant Maury, "when subjected to microscopic + examination, is found to consist of infusoria and organisms, whose + _habitat_ (place of abode) is not Africa, but South America, and in + the S. E. trade-wind region of South America. Professor Ehrenberg has + examined specimens of sea dust, from the Cape de Verdes and the + regions thereabout, from Malta, Genoa, Lyons, and the Tyrol, and he + has found such a similarity among them as would not have been more + striking had these specimens been all taken from the same pile. + + "South American forms he recognizes in all of them; indeed, they are + the prevailing form in every specimen he has examined. + + "It may, I think, be now regarded as an established fact, that there + is a perpetual upper current of air from South America to north + Africa, and that the volume of air in these upper currents, which + flows to the northward, is nearly equal to the volume which flows to + the southward with the N. E. trade-winds, there can be no doubt," + etc. + +Now, it is doubtless true that this dust is transported in a +counter-trade, and that such dust is found in South America, and is taken +up there by sand-spouts, like those of the ocean in form and action. Both +Humboldt and Gibbon have graphically described them. Yet I do not think +the point well taken. South-eastward of the Cape de Verdes, where the +surface-trades--which, becoming counter-trades, pass over these islands, +and, recurving, pass over the Mediterranean and south-western +Europe--should originate, there is a vast extent of unexplored continent +in the same latitude as the portion of South America where the dust is +found; and the same dry seasons, and the same spouts, in all probability, +exist in both. Until it be shown that such forms have no "_habitat_" in +central and southern and unexplored Africa, upon the same latitudes as in +South America, it may fairly be presumed that the dust is taken up there. +Indeed, the _curve_ upon which this dust is found to fall, in the greatest +quantities, is very remarkable, and corresponds remarkably with the _law +of curvature_ of the counter-trade we have considered, and with the +progress of a storm upon that coast, and over the Mediterranean, +investigated by Colonel Reid. (See Reid, on Storms and Variable Winds, p. +276.) This _curve clearly indicates the origin of the dust in South +Africa_. + +The second point is, that ashes from the volcanos of Mexico and Central +America have fallen to the north-east of the place where they were +ejected. Mr. Redfield has grouped these instances of volcanic eruption +usually cited, and I copy from him: + + "We learn from Humboldt, that in the great eruption of Jorullo, a + volcano of southern Mexico, which is 2,100 feet above the sea, in + latitude 18 deg. 45', longitude 161 deg. 30', the roofs of the houses in + Queretaro, more than 150 miles north, 37 deg. east from the volcano, were + covered with the volcanic dust. In January, 1845, an eruption took + place in the volcano of Cosiguina, on the Pacific coast of Central + America, in latitude 13 deg. north, and having an elevation of 3,800 + feet, the ashes from which fell on the island of Jamaica, distant 730 + miles north, 60 deg. east from the volcano. The elevated currents by + which volcanic ashes are thus transported are seldom or never of a + transient or fortuitous character; and these results, therefore, + afford us one of the best indications of their general course. Thus, + the progress of the higher portion of the trade-wind was marked by + the eruption of Tuxtla, latitude 18 deg. 30', longitude 95 deg., which + covered the houses in Vera Cruz with ashes, at the distance of 80 + miles north, 55 deg. west, and also at Perote, 160 miles north, 60 deg. west. + The ashes from the volcano, at St. Vincent, which fell at Barbadoes, + and east of that island, in 1812, mark the course of a current from + the westward, which appears there at times, in the region of clouds, + and may, perhaps, be connected with the permanent winds on the + Pacific coast of Mexico." + +As to one of the instances cited in the foregoing paragraph, that of +Tuxtla, it may be laid out of the case--the direction conforming +substantially to the assumed course of the counter-trade at that point. +St. Vincent lies W. N. W., or nearly so, of Barbadoes, and a N. W. or +westerly surface-wind, prior to, and during storms, is common in the West +Indies as the N. E. is here--both alike, blowing in opposition to the +progressive course of the storm. There is nothing strange or peculiar, +therefore, respecting that instance, or the existence of variable and +especially S. W. currents, between the trades, with occasional partial +condensation. + +The falling of the ashes from Cosiguina, upon Jamaica, has long and often +been cited, as proof that in the West Indies the prevailing upper currents +run from the S. W. But it has been ascertained that, _during the same +eruption, ashes fell 700 miles to the westward, on the deck of the +Conway_, a vessel then upon the Pacific Ocean. That case, therefore, does +not prove the absence of the S. E. counter-trade at the time, but only the +presence of another, and a different current above or below it--and it may +have been either, and transient. + +So of the Jorullo instance. Investigation would probably have shown that +ashes fell to the N. W., and that they were carried N. E. by a transient +S. W. wind produced by the existence of a storm to the eastward, or one of +those states of partial condensation of the counter-trade which often +produce currents at greater distances without a storm. Not one of these +cases disproves the existence of a S. E. counter-trade, and the invariable +N. W. progression of the storms of those latitudes demonstrates it. + +Occasional anomalous currents, depending upon storm action at considerable +distance, are found in our atmosphere, and doubtless are there also. Thus, +although the N. W. wind is almost invariably a surface wind, I have, in a +few instances, seen a N. W. set at a considerable elevation, converging +toward a peculiarly stormy state of atmosphere far south of us, about the +period of the spring equinox. And so in one or two instances I think I +have seen light cirro-stratus clouds _above_ the counter-trade, when it +ran very low, setting from the N. E., although the usual and almost +invariable location of the N. E. wind is below the counter-trade and the +stratus clouds of the storm. Aeronauts, too, have found these secondary +currents beneath a serene and cloudless sky. Indeed, the S. E. +counter-trade doubtless often induces a thin secondary current of S. W. +wind between itself and the surface-trade, in the same manner that similar +currents are induced with us, and every where. + +A question arises here of considerable interest, which, I confess, I can +not answer to my own satisfaction. It is, whether there be, or not, _an +eastern progression of the body of the atmosphere above the machinery of +distribution_. I have thought there was, and that in set fair weather I +had seen a peculiar kind of cirro-cumulus cloud, in patches, the small +cumuli very distinct and rounded, moving due east, which indicated such a +current. But I am not satisfied, from my own observation, that it is so, +nor is it easy to determine the question. The moisture of evaporation +rarely, if ever, ascends to any considerable elevation, and the upper +strata must be very dry. Hence, condensation, if it takes place, is thin, +and perhaps often undiscernable. Investigations upon mountains prove +little, for the winds of the inferior strata rush up their sides and over +them. It is an open question, and future observation may solve it. The +prevailing opinion seems to be that there is. If the theory of Oersted, in +relation to the circular currents of a magnet, be true, there should be +such a progression produced by opposite secondary currents, unless, +indeed, it be also true that those currents are inoperative at so great a +distance, or their influence barely suffices to retain the attenuated +atmosphere in its place. Perhaps the investigations of Ampere conflict +with it. But it is worth while, I think, for philosophers to inquire +whether the transverse position of the needle upon the wire is not the +effect of the central _longitudinal_ currents, conforming to the circular +currents of the wire, and whether it is not owing to the production of the +same currents in a globe by the circular currents of Ampere, that the +globe is magnetized, and the needles made to dip. + + + + +CHAPTER VIII. + + +It is exceedingly desirable, in a practical point of view, to understand +the precise character of the reciprocal action which takes place between +the earth and the counter-trade, and produces the varied phenomena which +mark our climate. We have seen that the same laws, other things being +equal, operate every where, and that analogies may be sought in the +character of those phenomena elsewhere, under the same, or different, +modifying circumstances. Looking, therefore, at the magneto-electric +movable machinery as a whole, and its influence upon the atmospheric +circulation and conditions, we find many facts which point to a primary +action in the counter-trade, and others that point as significantly to a +primary local-inducing-action in the earth. Let us briefly review those to +which we have alluded, and advert to some others, and see what solution of +the question they will justify: + +The belt of inter-tropical rains appears to be, in width, and amount of +precipitation, and annual travel north and south, proportionate to the +volume of trades which blow into it, the quantity of moisture they +contain, and the elevation of the surface over which they meet. + +South America is the most thoroughly-watered country within the tropics, +except, perhaps, portions of Hindoostan, Burmah, Siam, etc., on +south-eastern Asia. The contrast between both, and Africa, as far as +explored, and as shown by its rivers, is most obvious. The Amazon, alone, +delivers more water to the ocean than all the rivers of Africa. + +Of the width of the belt of rains over Africa, in the interior, we know +little. Its northern extension is less, by from 7 deg. to 10 deg., than the same +belt over South America, the West Indies, and Mexico. Probably its +southern is also. Upon South America, the southern edge is carried down to +Cochabamba, in latitude 18 deg., and probably to 25 deg., to the northern edge of +the coast-desert of Peru, while it is rarely, if ever, found over the +Atlantic below 7 deg., a difference of 12 deg. to 20 deg.. Over South America, too, +the quantity of water which falls is also vastly in excess of that which +falls upon the Atlantic. The main cause of these differences is obvious. +The N. E. counter-trades which blow over Africa, originate on a surface +which is rainless, as eastern Sahara, Egypt, Arabia, etc., or subject to a +dry season by the northern ascent of the southern line of the +extra-tropical belt, as the Barbary States, Syria, Persia, etc., and their +supply of moisture is necessarily scanty. On the south, the S. E. trades +originate, in part, upon the eastern portion of southern Africa, and, in +part, upon the Indian Ocean, and from the latter source, and a portion of +the Mediterranean, doubtless most of the water which falls upon Central +Africa, is derived. + +The N. E. and S. E. trades which blow into the inter-tropical belt upon +the eastern portion of the Atlantic, originate upon similar surfaces, and +with like effect. Thus, the S. E. trades, in summer, are from the Southern +portion of Africa, and the N. E., in part, from the Mediterranean; and, in +winter, the N. E. from the deserts, Senegambia, Nigritia, etc., and the S. +E., owing to the narrowing of the African continent, mainly from the South +Atlantic and Indian Oceans. Going west, the belt widens, and its range +increases until the Andes are reached; but under their lee, on the western +side, a totally different state of things is found, and the belt of the +coast becomes broken and irregular, as we have seen in the citation from +Maury. + +The width, extension, and excessive precipitation of the belt, over South +America, follow the same law. The South Atlantic widens out by the +trending of the coast to the S. W., and furnishes a large area for the +unobstructed formation and evaporative action of the S. E. trades. So the +trending of the coast to the N. W., from 5 deg. south to the northward, opens +a large area for a like formation and action of the N. E. trades. No +correspondingly favorable circumstances exist any where, except, perhaps, +around Hindoostan, and there the fall of rain is very excessive in some +places, as on the Kassaya hills, to the extent of 400 inches per annum. In +addition to this, the magnetic line of no variation, and of greater +intensity, which runs from our magnetic pole, obliquely, S. S. E., to its +opposite and corresponding pole in the southern hemisphere, enters the +Atlantic on the coast of North Carolina, and traverses it, and the eastern +portion of South America, through the whole trade-wind region. The +table-lands, and slopes, and high mountain peaks, meet the trades +successively, as they go west, and the latter wrench from them, to an +unusual extent, their moisture; depressing the line of perpetual snow, by +an increase of quantity on the eastern sides, several thousand feet, as it +is for a like cause depressed on the southern side of the Himmalayas. On +the eastern slopes and tops of the Andes, as we have seen, and owing to +their elevation, falls the moisture which, according to the working of the +machinery, and the law of curvature, should bless the coast line of Peru +and northern Chili, the eastern Pacific, northern Mexico, California, +Utah, and New Mexico; and, while the Andes stand, the curse of comparative +aridity must rest upon them all. + +Southern Chili, and western Patagonia are supplied by the N. E. trades, +which originate in the West Indies, the Gulf of Mexico, and the Caribbean +Sea, and the Pacific, off Central America, in the neighborhood of the Bay +of Panama. But there, again, the same effect of elevation is seen. The +mountain slopes of southern Chili and Patagonia are abundantly supplied, +and their mountain ranges are drenched with rain, while eastern Patagonia +and southern Buenos Ayres, under their lee, are comparatively dry. So the +S. E. trades, which originate off the western coast of South America, +curve in upon, and aided by the oceanic currents, supply, abundantly, the +N. W. coast of this continent, north of California; and there, too, the +coast, and its elevated ranges, receive, as we have seen, a very large +proportionate supply of their moisture. Substantially, the same state of +things, as far as circumstances permit, is reproduced upon Malaysia, +Hindoostan, etc., and the interposition of arid New Holland upon the +evaporating trade-surface may be distinctly traced upon south-western +Asia. Deserts abound there; the Caspian Sea receives the drainage of a +very large surface, without an outlet; their southern line of +extra-tropical rains is carried up very far in summer, and their dry +season is intensely hot. (See an article in the American Journal of +Science, for July, 1846, by Azariah Smith.) + +Another fact in this connection is worthy of a moment's consideration. The +magnetic equator, as sought by the dipping needle, is not coincident with +the geographical one. Humboldt found it, on the Andes, at 7 deg. 1' south, and +it has been found still lower in the Atlantic. Over Africa it rises above +the geographical equator, and descends again on the Indian Ocean. About +midway the Pacific, it becomes coincident with the equator of the earth +again. (See diagram, on page 83.) Perhaps it is not known, with certainty, +why this is so. The south pole may be situated nearer the geographical +pole than the north one--but this is not believed to be so, nor could it +make the difference. The greatest southern depression of the magnetic +equator is found where the lines of greatest intensity, and of no +variation, are found; and at the more intense of these lines exists the +greatest depression. From this, I think, it may be inferred that the +needle is affected by the greater magnetic intensity of the northern +hemisphere, to which it may yet appear the obliquity of the earth's axis +is owing. However this may be, or whatever the cause, no marked effect is +produced upon the trades. The S. E. trades, by reason of the greater +extent of ocean-surface on which they originate, are every where the most +extensive, regular, and forcible. The south polar waters, from which they +rise, are every where trenching upon, and overriding, the north polar +ones; and thus, by a most beneficent provision, the greater portion of the +habitable surface is placed in the northern hemisphere, and the principal +portion of the southern is left open to an extensive, active evaporative +action, which supplies the northern habitable surface with a large excess +of the needed moisture. + +The condensation, and consequent precipitation, which takes place at the +passing of the trades, as we have already said, over the ocean and +lowlands, takes place mainly in the day-time. Upon the table-lands and +mountain-ranges, it often continues during the evening and night. The +morning, and early part of the day, however, in tropical countries, are +generally fair at all elevations. + +Storms also originate in the equatorial belt, and issuing forth in great +volume and with great intensity of action, find their way up even within +the Arctic circle. Those which pass over this continent, or the northern +Atlantic, generally originate in the West Indies, some of them over the +Caribbean Sea, some over the islands, and some over the open ocean to the +east of them; and, nearly all the most violent, during the months of +August, September, and October. It would seem most probable that the +primary action in such cases was in the trades themselves, but it is by no +means certain that such is the case. This is the class of storms of which +Mr. Redfield has industriously investigated some twenty or more; Mr. Espy +some, and Lieutenant Porter two. Their course, when very violent, is often +more directly north than that of storms, however violent, which originate +north of the calms of Cancer, owing, perhaps, to their greater +paramagnetic character. This course I have myself observed, in several +instances, about the period of the autumnal equinox--never, however, more +southerly than from S. W. to N. E., on the parallel of 41 deg., except in +three, and, perhaps, four, instances, when it has been S. W. by S. to N. +E. by N. I know of no class of storms in relation to which the evidence of +primary action in the counter-trade is stronger than in those of the class +which originate on the ocean east of the Windward Islands. But it is not +satisfactory as to them. Doubtless the conflict of polarities between the +passing trades is sufficient to produce the showers and rains which are +ordinarily found over the ocean and lowlands, in the equatorial belt; but +it is doubtful whether it is sufficient to produce such extensive, +long-continued, and violent action, as that which characterizes the +hurricane autumnal gales. + +They occur, too, at the time when the whole machinery of distribution has +reversed its course, and is rapidly pursuing its journey south. It is a +period of great magnetic disturbance, over both land and sea; of more +active gales and local-increased precipitation. At the Magnetic +Observatory of Toronto, Canada West, these disturbances are carefully and +systematically observed, and their maxima, or periods of greatest +disturbance occur in April and September. (See Silliman's Journal, new +series, vol. xvii. p. 145.) + +The tendency to volcanic action is not as great at the autumnal, as at the +vernal equinox, for the reason that most of the volcanic action of the +western hemisphere develops itself now upon South rather than North +America. But both exist, and are active, and what are improperly termed +equinoctial storms, and gales, and rains, are proverbial during, or just +subsequent to, both periods with us--as they are when the same change, +called the breaking up of the monsoons, takes place in the line of +magnetic intensity, over southern and eastern Asia. A volume might be +filled with extracts, showing, at least, most remarkable coincidences +between violent volcanic action and great atmospheric disturbance. Perhaps +the increased fall of rain at and after the equinoxes, in the northern +hemisphere, and in certain localities subject to volcanic activity, is as +strikingly illustrated by the register, kept by Mr. Johnson, on the +volcanic Island of Kauai, one of the Hawaiian group, already alluded to, +as in any other case, although it is by no means a singular one. The +greatest fall of rain, in any month except April and October, was eight +inches. In April, the fall was fourteen inches, in October, eighteen +inches. Neither the equatorial, nor extra-tropical belt, were over the +island during those months; but they were the N. E. trades, and the result +was owing solely to the interposition of high volcanic mountains, _in a +state of disturbance_, into, or near, the strata of the counter-trade. Mr. +Dobson, in stating a theory to which we shall hereafter advert, advances +the following proposition: + +"7. _Cyclones (hurricanes) begin in the immediate neighborhood of active +volcanoes._ The Mauritius cyclones begin near Java; the West Indian, near +the volcanic series of the Caribbean Islands; those of the Bay of Bengal, +near the volcanic islands on its eastern shores; the typhoons of the China +Sea, near the Philippine Islands, etc." + +The peculiar stormy state of the atmosphere, over the Gulf Stream, to +which I have alluded, certainly affords no evidence of primary atmospheric +action. It is a body of south polar water, pursuing its way under the +guidance of magnetism--maintaining its polarity--arched somewhat like the +roof of a house, by the outward pressure of a cold north polar current +which it has met to the east of the Banks of Newfoundland, and forced to +take an in-shore course to the southward, and the bodies of water which +the rivers discharge, and a conflict with the north polar surface-winds +which sweep over it, and fogs, and thunder, and rain, are a matter of +course. Dr. Kane met a portion of this singular current in Baffin's Bay, +north of 75 deg., which had preserved its characteristics and a considerable +proportionate excess of heat, although it probably had been around +Greenland, or found its way to the west, toward the magnetic pole, through +some of its northern fiords or straits. (Grinnel Expedition, p. 120.) + +The investigations of Lieutenant Maury show, that when the Gulf Stream +turns to the eastward, crossing the lines of declination at right angles, +as the counter-trades also seem to do in the same latitude, it is _carried +up, in summer, several degrees to the north_, and descends again in +winter--thus demonstrating its connection with the shifting magnetic +machinery which controls alike the ocean, the atmosphere, and the +temperature of the earth.[7] + +There are other irregularities which deserve to be noticed, in this +connection, although the analogical evidence they afford is far from being +decisive. + +I have already said that it was within my own observation, that +alternating lines of heat and cold, as well as rain and drought, existed +frequently, without regard to latitude, following, to some extent, the +course of the counter-trade. Such lines have been observed by others. + +Thus, Mr. Espy, after describing a snow-storm, which was followed by a +very cold N. W. wind, of several days' continuance, says: + + "This cold air covered the whole country, from Michigan to the + eastern coast of the United States, till the beginning of the great + storm of the 26th January; and, what is worthy of particular notice + is, that _the temperature began to increase first in the north and + north-west_. On the morning of the 25th, in the north-western parts + of Pennsylvania, and northern parts of New York, the _thermometer_ + had already _risen in some places 30 deg._, and, in others, _above 40 deg._. + While in the S. E. corner of Pennsylvania, and in the S. E. corner of + New York it had not _begun to rise_. The _wind_ also began to change + from the _north-west_ to _south_ and _south-east_, _first_ in the + north-west parts of Pennsylvania and New York, some time before it + commenced in the south-east of those States; and, during the whole of + the 25th, the thermometer, in the north of New York, continued to + rise, though the wind was blowing from the southward, where the + thermometer was many degrees lower." + +Thus, too, Mr. Redfield (American Journal of Science, November, 1846, p. +329): + + "On the contrary, in times of the greatest depression of the + thermometer, in numerous instances, the cold period has been found to + have first taken effect in, or near, the tropical latitudes, and the + Gulf of Mexico, and has thence been propagated toward the eastern + portions of the United States, in a manner corresponding to the + observed progression of storms." + +This was because the cold N. W. wind which _followed_ storms began to +follow them as the storms curved and passed to the N. E. + +They occur in Europe also. Says Kaemtz: + + "Such contrasts are not uncommon in Europe, and, in this respect, the + Alps form a remarkable limit; for they separate the climates of the + north of Europe from the Mediterranean climates, where the + distribution of rain is not the same as in the center of Europe. + Hence the differences between the climates of the north and south of + France. _If the winter is mild in the north_, the newspapers are + filled with the lamentations of the _Italians_ and _Provencals_ at + the _severity of the cold_." + +These facts seem to indicate a primary action in the counter-trade. +Probably in connection with one class of storms they do, and with another +do not. I shall endeavor to show the distinction when I come to the +classification of storms. + +The difference of seasons in this country, and over the entire northern +hemisphere, is often very great. In a remarkable work of a remarkable +man--"A Brief History of Epidemic and Pestilential Diseases," by Noah +Webster, published in 1799, 2 vols.--a history of the weather for about +two centuries--1600 to 1799 inclusive, is given generally, and then in a +tabular form. Those who think that every considerable extreme which occurs +exceeds any thing before known, will do well to consult that work. +Droughts are described, where "there was not a drop of rain for three or +four months, and cattle were fed upon the leaves of the trees." Winters, +so intensely cold that the thermometer fell to 20 deg. below zero, at +Brandywine; or so mild that there was little frost, and people upon +Connecticut River plowed their fields, and the _peach trees blossomed in +Pennsylvania in February_. These extremes generally existed in Europe and +America at the same time, but occasionally they were opposite and +alternate. Says Mr. Webster, in summing up the facts (vol. ii. p. 12): "It +is to be observed that in some cases a severe winter extends to both +hemispheres, sometimes to one only, and in a few cases to a part of a +hemisphere only. Thus in 1607-8, 1683-4, 1762-3, 1766-7, 1779-80, 1783-4, +the severity extended to both hemispheres. In 1640-41, 1739-40, and in +other instances, the severe winter in Europe preceded, by one year, a +similar winter in America. In a few instances, severe frost takes place in +one hemisphere during a series of mild winters in the others; but this is +less common. In general, the severity happens in both hemispheres at once, +or in two winters, in immediate succession; and, as far as this evidence +has yet appeared, this severity is closely attendant on volcanic +discharges, with very few exceptions." + +It will be seen that Dr. Webster (LL.D. and not M.D., and therefore the +remarkable character of the work) attributes great influence to +earthquakes and volcanic action. Probably he is correct in this. The +present active volcanic action of the western hemisphere is nearly all +within the trade-wind region, from Mexico to Peru inclusive. The West +India islands are of volcanic origin, and the influence of volcanic action +is not confined to a concussion of the earth, or the eruption of mud and +lava. Its connection with magnetic action, and disturbance, is +unquestionable. But whether they operate to increase or diminish the +trades, and the extent to which they induce violent electric action and +storms within and without the tropics, is a question which further +observation must determine. The ripples of the ocean, compared by +Lieutenant Banvard to that of a "boiling cauldron, or such as is formed by +water being forced from under the gate of a mill-pond," are met with in +the vicinity of volcanic islands, where hurricanes and water-spouts +originate, and have been observed to precede storms, and be connected with +a falling barometer. But whether they are volcanic or magneto-electric, +it is difficult to determine. Dr. Webster remarks, as the result of +observation, during the 17th century, that earthquakes had a N. W. and S. +E. progression in the United States, and especially in New England. In a +recent article, Professor Dana has examined, with great ability, the +general and remarkable trending of coast lines, groups of islands, and +ranges of mountains, from N. E. to S. W. and from N. W. to S. E. (American +Journal of Science, May, 1847.) + +The line of magnetic intensity, which connects our magnetic pole with its +opposite, is now upon this continent nearly a N. W. and S. E. line, and +the pole is fast traveling to the west. It may, and probably will yet, be +established, that there is an intimate connection between the cause of +volcanic action within the earth, to which the upheaval of the N. W. and +S. E., and N. E. and S. W. ranges were due, and of magnetic action +without, and between both, and the cause of _the S. E. extension_ of our +summer storms and belts of showers and barometric _waves_, and the +_peculiar N. W. wind_. Our limits do not permit us to pursue the subject. + +Much influence upon the weather has been attributed to the spots upon the +sun. These spots are supposed to be breaks or openings in the luminous +atmosphere or photosphere of the sun, through which its dark nucleus body +is seen. Counselor Schwabe, of Dessau, has made them his study since 1826, +and has arrived at some singular results. They seem to be numerous--in +groups--and to appear periodically with minima and maxima of ten years. +As the result of his observations, from 1826 to 1850, he gives us the +following table and remarks: + + +-----------------------------------------------+ + | Year. | Groups. | Days showing | Days of | + | | | no spots. | Observation. | + |-------|---------|--------------|--------------| + | 1826 | 118 | 22 | 277 | + | 1827 | 161 | 2 | 273 | + | 1828 | 225 | 0 | 282 | + | 1829 | 199 | 0 | 244 | + | 1830 | 190 | 1 | 217 | + | 1831 | 149 | 3 | 239 | + | 1832 | 84 | 49 | 270 | + | 1833 | 33 | 139 | 267 | + | 1834 | 51 | 120 | 273 | + | 1835 | 173 | 18 | 244 | + | 1836 | 272 | 0 | 200 | + | 1837 | 333 | 0 | 168 | + | 1838 | 282 | 0 | 202 | + | 1839 | 162 | 0 | 205 | + | 1840 | 152 | 3 | 263 | + | 1841 | 102 | 15 | 283 | + | 1842 | 68 | 64 | 307 | + | 1843 | 34 | 149 | 312 | + | 1844 | 52 | 111 | 321 | + | 1845 | 114 | 29 | 332 | + | 1846 | 157 | 1 | 314 | + | 1847 | 257 | 0 | 276 | + | 1848 | 330 | 0 | 278 | + | 1849 | 238 | 0 | 285 | + | 1850 | 186 | 2 | 308 | + +-----------------------------------------------+ + + "I observed large spots, visible to the naked eye, in almost all the + years not characterized by the minimum; the largest appeared in 1828, + 1829, 1831, 1836, 1837, 1838, 1839, 1847, 1848. I regard all spots, + whose diameter exceeds 50", as large, and it is only when of such a + size that they begin to be visible to even the keenest unaided sight. + + "The spots are, undoubtedly, closely connected with the formation of + faculae, for I have often observed faculae, or narben, formed at the + same points from whence the spots had disappeared, while new solar + spots were also developed within the faculae. Every spot is surrounded + by a more or less bright, luminous cloud. I do not think that the + spots exert any influence on the annual temperature. I register the + height of the barometer and thermometer three times in the course of + each day, but the annual mean numbers deduced from their observations + have not hitherto indicated any appreciable connection between the + temperature and the number of the spots. Nor, indeed, would any + importance be due to the apparent indication of such a connection in + individual cases, unless the results were found to correspond with + others derived from many different parts of the earth. If the solar + spots exert any slight influence on our atmosphere, my tables would, + perhaps, rather tend to show that the years which exhibit _a larger + number of spots_ had a _smaller number of fine days_ than those + exhibiting few spots." + +These observations _seem_ to show that the spots exert no influence upon +the weather, and to be satisfactory. But, perhaps, they are not entirely +so. No effect would, of course, be expected from day to day, and perhaps +the annual mean may not be seriously disturbed, and yet the spots may +seriously affect the seasons. Popular tradition has fixed upon certain +periods, of 10, 20, and 40 years, for the return of winters of unusual +severity; and the tables of Mr. Webster, and other facts, show that it is +not wholly without foundation. If we, and those we have cited, are not +mistaken in most of the views expressed, the natural effect of a partial +interception or failure of the sun's rays, by or from the existence of the +spots, would be to decrease the exciting power of the solar rays upon +terrestrial magnetism, and, as a consequence, the volume of the trades and +their amount of moisture. This would increase the _mean_ heat of the +summer in the temperate zone--for the _less_ the volume of trade, the less +precipitation and variable wind, and succeeding polar waves of cooler air, +and the greater mean heat. On the other hand, the same cause, and the +feebler heating power of the sun's rays, would make the winters more +severe, both from an absence of a portion of heat, derived directly from +the sun's rays, and a less mitigating influence, from the action of the +trade, by reason of its decreased volume. So, too, the absence of spots, +and a more powerful influence from the solar rays, may gradually carry +the machinery further north in summer, and further south in winter, and +thus make the _seasons extreme_ without seriously disturbing the mean of +the year. And both these may occur in a more marked degree over our +intense magnetic area than in Europe. I am satisfied that they do so +occur. That the partial failure of the sun's rays limits the transit of +the machinery, and the volume of the trades during the latter half of the +decade, and extends the transit and increases the volume during the first +half, producing an occasional severe summer drought and severe winter, in +the warmest portion of the decade. And that the variations correspond with +the difference in the character and number of the spots in different +decades, and hence the longer and shorter periods. + +Turning to the tables of Dr. Webster, we find that a general tendency to +extreme seasons does seem to exist from the 6th to the 10th year of every +decade, and especially of every alternate decade. The periods of 1707-8, +1728, 1737 and 1739, 1749-50, 1758-9, 1779-80, 1798-9, are those in which +the tendency was seen most decided. These tables are very general. The +thermometer was not perfected till about 1700, and did not get into +general use before 1750. There were very few meteorological registers +kept, or accessible to Dr. Webster. Hence he was obliged to resort to such +other sources of information as were open to him, and such statements as +he found are not always entirely reliable. The oldest inhabitant is apt to +express himself very strongly respecting present extremes, and fail +somewhat in his recollection of those which have past. Still his tables +afford general and obvious evidence of the regularity of those periodic +conditions. + + +---------------------------------------------------------+ + |A. D.| Summer. | Winter. | + |-----|-------------------------|-------------------------| + | 1701| hot and dry | .... | + | 1702| hot and dry | .... | + | 1703| .... | .... | + | 1704| dry Europe | .... | + | 1705| .... | .... | + | 1706| hot, dry Europe | .... | + | 1707| very hot | .... | + | 1708| .... | very severe | + | 1709| .... | .... | + | 1710| .... | .... | + | 1711| .... | cold Europe | + | 1712| wet England | .... | + | 1713| wet England | mild | + | 1714| dry and hot | .... | + | 1715| dry | .... | + | 1716| very dry | severe | + | 1717| .... | severe | + | 1718| hot and wet | .... | + | 1719| .... | cold America | + | 1720| dry Europe | .... | + | 1721| .... | .... | + | 1722| cold, wet | .... | + | 1723| .... | cold | + | 1724| wet England | .... | + | 1725| wet England | .... | + | 1726| .... | .... | + | 1727| dry, hot Amer. | .... | + | 1728| hot Amer. | severe Europe | + | 1729| .... | .... | + | 1730| .... | very cold Eng. | + | 1731| .... | .... | + | 1732| .... | severe Amer. | + | 1733| dry Eng. | .... | + | 1734| .... | .... | + | 1735| wet | .... | + | 1736| wet | .... | + | 1737| .... | very severe Am. | + | 1738| .... | .... | + | 1739| wet England | very severe Eng. | + | 1740| .... | very severe Am. | + | 1741| .... | .... | + | 1742| .... | severe Syria | + | 1743| hot | .... | + | 1744| .... | .... | + | 1745| .... | .... | + | 1746| .... | .... | + | 1747| hot and dry | severe | + | 1748| dry | .... | + | 1749| very dry | .... | + | 1750| very hot | very severe | + | 1751| wet England | severe Amer. | + | 1752| very hot Amer. | .... | + | 1753| .... | severe | + | 1754| .... | mild Amer. | + | 1755| .... | severe Europe | + | 1756| .... | severe Syria | + | 1757| .... | .... | + | 1758| hot | .... | + | 1759| .... | severe | + | 1760| .... | .... | + | 1761| very dry Amer. | .... | + | 1762| very dry Amer. | severe | + | 1763| .... | .... | + | 1764| hot Europe | .... | + | 1765| hot Europe | severe Europe | + | 1766| hot and dry Eur. | very severe | + | 1767| .... | cold | + | 1768| hot | .... | + | 1769| hot | .... | + | 1770| wet England | .... | + | 1771| wet Am. & Eng. | cold Europe | + | 1772| hot America | Am., great snow | + | 1773| .... | .... | + | 1774| .... | severe Europe | + | 1775| .... | .... | + | 1776| hot | severe Europe | + | 1777| .... | .... | + | 1778| hot | mild | + | 1779| hot Eng. | very severe | + | 1780| .... | .... | + | 1781| .... | .... | + | 1782| dry Amer. | .... | + | 1783| hot | very severe | + | 1784| hot | .... | + | 1785| dry Europe | cold | + | 1786| cool | cold | + | 1787| cool | .... | + | 1788| rainy Amer. | cold | + | 1789| cool spring, hot summer | severe Eur., mild Amer. | + | 1790| .... | .... | + | 1791| very hot Am. | cold | + | 1792| .... | .... | + | 1793| hot, dry Am. | mild Amer. | + | 1794| .... | severe Europe | + | 1795| Amer., hot, rainy | .... | + | 1796| Autumn very Dry Am. | cold Amer. | + | 1797| cool Am. | severe Amer. | + | 1798| very hot } | { long & severe | + | 1799| very dry Am. } | { Amer. & Eur. | + +---------------------------------------------------------+ + +Still more definite evidence is found in the meteorological tables of Dr. +Holyoke and Dr. Hildreth, and an account, by Dr. Hildreth, of the seasons +when the Ohio River was closed or obstructed by ice, found in Silliman's +Journal, new series, vol. xiii. p. 238. + +Thus, we have, from the tables of Dr. Holyoke, the following annual means, +from 1786 to 1825, inclusive. I have arranged them in periods of five +years. It will be seen that there are three peculiarities observable. +First, a marked difference between the first and second periods of the +decade, corresponding, generally, with the presence or absence of the +spots. Second, a difference in the mean of the decades which may well be +supposed to correspond with the difference in the number or size of the +spots since a like difference is observable in number and size, and the +time when they reached their maxima and minima, in the table of Schwabe. +And, third, there are occasional single cold years during the warm period, +and these correspond with what the tables of Dr. Webster show for both the +sixteenth and seventeenth centuries. In relation to this, it should be +remembered that volcanic action is a frequent and powerful disturber of +the regular action of terrestrial magnetism, and that the extremes, for +that reason, are frequently meridional or local and alternating; and to +that cause very great extremes, and marked exceptions, may be due, +notwithstanding the spots upon the sun may exert an influence in producing +hot summers and cold winters toward the close of each decade. Thus, to +select an instance to illustrate this and explain an anomaly: The coldest +season during the whole period, embraced in the following tables, is that +of 1812. This occurs during the decrease of spots, and the warm half of +the decade. Turning to the table of volcanic action, and of earthquakes, +found in the Report of the British Association for 1854, we find that year +was remarkable for earthquakes in the United States and South America. In +December, 1811, earthquakes commenced in the valley of the Mississippi, +Ohio, and Arkansas, felt also at places in Tennessee, Kentucky, Missouri, +Indiana, Virginia, North and South Carolina, Georgia, and Florida, though +not so severely east of the Alleghanies, _which continued until 1813_. +About the same time they commenced in Caraccas, and, in March, 1812, +became severe over the greater portion of the northern section of South +America, and in the Atlantic. No such general and continued succession of +earthquakes occurred during the other periods embraced in the tables, and +the mean of the following five years was very low, embracing the memorable +cold summer of 1816. + + +---------------------------------------------------------------+ + | Cold Period. | Warm Period. | Cold Period. | Warm Period. | + |---------------|---------------|---------------|---------------| + |1786 48 deg..53 |1791 48 deg..963|1796 48 deg..678|1801 50 deg..432| + |1787 47 deg..88 |1792 48 deg..44 |1797 48 deg..135|1802 50 deg..794| + |1788 47 deg..676|1793 50 deg..96 |1798 49 deg..471|1803 50 deg..24 | + |1789 47 deg..68 |1794 50 deg..768|1799 48 deg..291|1804 48 deg..328| + |1790 46 deg..53 |1795 50 deg..173|1800 49 deg..989|1805 50 deg..792| + |---------------|---------------|---------------|---------------| + |Mean of | | | | + |period 47 deg..659|Mean 49 deg..901|Mean 48 deg..910|Mean 50 deg..117| + |---------------|---------------|---------------|---------------| + |---------------|---------------|---------------|---------------| + |1806 47 deg..982|1811 50 deg..76 |1816 47 deg..113|1821 48 deg..15 | + |1807 48 deg..132|1812 45 deg..28 |1817 46 deg..277|1822 49 deg..81 | + |1808 49 deg..485|1813 47 deg..702|1818 48 deg..009|1823 47 deg..58 | + |1809 47 deg..92 |1814 48 deg..279|1819 50 deg..75 |1824 49 deg..25 | + |1810 49 deg..001|1815 47 deg..607|1820 48 deg..70 |1825 50 deg..99 | + |---------------|---------------|---------------|---------------| + |Mean 48 deg..505|Mean 47 deg..925|Mean 48 deg..169|Mean 49 deg..15 | + +---------------------------------------------------------------+ + +The tables of Dr. Hildreth, from 1826 to 1854, inclusive, furnish, +generally, evidence of a like character. There are, however, an anomaly or +two which will be observed. From 1826 to 1830, the mean is high during +the period when spots were at a maximum. But that maximum embraced a much +less number of spots than the two succeeding ones. A contrast appears in +the tables of Dr. Hildreth, during the early period, for Dr. Holyoke's +register, for 1827, puts it _below the mean_, but Dr. Hildreth's one of +the _highest of the half century_. In 1835 commenced a period when the +spots were much more numerous, and from 1835 to 1838, inclusive, the +seasons were correspondingly below the mean. From that period to 1844 a +gradual and slightly irregular rise took place, excepting the year 1843, +when another cold year intervened. The table of earthquakes, published by +the British Association, closes with 1842, and I have not access to any +others. The occurrence of such cold years, in the warm period, at +intervals during the two centuries previous, and in 1812, and onward, and +evidently owing to increased volcanic action beneath the western portion +of the northern hemisphere, justifies the belief that the low temperature +of 1843 was owing to the same cause. The following are the means from the +tables of Dr. Hildreth: + + +----------------------------------------------------------------+ + |1826 54 deg..00|1831 50 deg..87|1836 50 deg..03|1841 52 deg..18|1846 53 deg..64| + |1827 54 deg..92|1832 52 deg..42|1837 51 deg..57|1842 52 deg..83|1847 52 deg..00| + |1828 55 deg..22|1833 54 deg..56|1838 50 deg..62|1843 50 deg..77|1848 52 deg..50| + |1829 52 deg..38|1834 52 deg..40|1839 52 deg..54|1844 53 deg..25|1849 52 deg..09| + |1830 54 deg..93|1835 50 deg..65|1840 52 deg..35|1845 52 deg..73|1850 51 deg..48| + |------------|------------|------------|------------|------------| + |Mean 54 deg..29|Mean 52 deg..18|Mean 51 deg..52|Mean 52 deg..35|Mean 52 deg..32| + +----------------------------------------------------------------+ + +The observations of Dr. Holyoke were made at Salem, Massachusetts; those +of Dr. Hildreth at Marietta, Ohio. + +The following, in relation to the freezing of the Ohio River, is evidence +of a different kind, but shows the same general correspondence, and +particularly _the mildness of the winters when there were few spots_, and +their severity from 1836 to 1838, inclusive, when the spots were most +numerous: + + 1829.--River open all winter--some floating ice. + 1830.--River closed 27th January. + 1831.--Floating ice--closed 23d January--opened 20th February. + 1832.--Closed in December, which was a very cold month--opened January + 8, and remained open all winter. + 1833.--Open all winter. + 1834.--Open all winter. + 1835.--Closed January 6--opened the last of the month--cold. + 1836.--Closed 28th January--opened 25th February. + 1837.--Closed from 8th December to 8th February. Cold year. + 1838.--Closed from 13th January to 13th March. Cold year. + 1839.--Closed from 6th December to 13th January. + 1840.--Closed 29th December--opened 15th January. + 1841.--Closed 3d January--opened 8th do. + 1842.--Open all winter. + 1843.--Closed 28th November--opened 5th December--open all the rest of + the winter. + 1844.--Open all winter. + 1845.--Open all winter. + 1846.--Closed 5th December--opened again a few days--closed again on the + 26th. It is not stated how long it remained closed. + 1847.--Open all winter. + 1848.--Much floating ice, but not closed--heavy rains and floods. + 1849.--Floating ice in January, but not closed. + 1850.--Floating ice, but not closed. + 1851.--Open all winter--a little ice. + + (December in the above table, means December previous). + +This is more reliable as to the winter season than the tables of annual +means--although the evidence they afford, making due allowance for the +exceptions, is very striking. + +I shall return to this part of the subject again. + +But there is other evidence of the influence of these spots. Their +connection with the irregular magnetic disturbance of the earth has been +distinctly traced. Colonel Sabine, President of the British Association, +in his opening address, September, 1852, after reviewing the recent +discoveries in magnetism, says:-- + + "It is not a little remarkable that this periodical magnetic + variation is found to be identical in period, and in epochs of maxima + and minima, with the periodical variation in the frequency and + magnitude of the _solar spots_, which M. Schwabe has established by + twenty-six years of unremitting labor. From a cosmical connection of + this nature, supposing it to be finally established, it would follow + that the decennial period, which we measure by our magnetic + instrument, is, in fact, a solar period, manifested to us, also, by + the alternately increasing and decreasing frequency and magnitude of + observations on the surface of the solar disc. May we not have in + these phenomena the indication of a cycle, or period of _secular + change in the magnetism of the sun_, affecting visibly his gaseous + atmosphere or photosphere, and sensibly modifying the magnetic + influence which he exercises on the surface of our earth?"--American + Journal of Science, new series, vol. xiv. p. 438. + +I think it may fairly be inferred, that although these spots do not +occasion the "cold spells" and "hot spells," and other transient +peculiarities, they do materially affect the _mean_ temperature of the +year, and exert an obvious influence when at their maxima; and there is a +tendency to an increase of the heat and dryness of summer, and the +severity of winter, at the periods named, in our excessive climate, and a +well-established connection between the spots and magnetic disturbances +and variations. + +Popular opinion has ever attributed to the moon a controlling effect upon +the changes of the weather. If it be dry, a storm is expected _when the +moon changes_; or if it be wet, dry weather. Such popular opinions are +usually entitled to respect, and founded in truth. But every attempt to +verify _this opinion_, by careful observation and registration, has +failed. Weather-tables and lunar phases, compared for nearly one hundred +years, show four hundred and ninety-one new or full moons attended by a +change of the weather, and five hundred and nine without. The celebrated +Olbers, after _fifty years of careful observation_ and comparison, decided +against it. So did the more celebrated Arago, at a more recent +date--summing up the result of his observations by saying--"Whatever the +progress of the sciences, never will observers, who are trustworthy and +careful of their reputation, venture to foretell the state of the +weather." Still, the moon may influence the weather, though she may not +effect changes at her syzygies or quadratures, and this subject should not +be too summarily dismissed. That the moon can not effect changes at the +periods named seems philosophically obvious. She changes, for the _whole +earth_, within the period of twenty-four hours; yet, how varied the state +of things on different portions of its surface. The equatorial belts of +trades, and drought, and rains, cover from fifty to sixty degrees of its +surface, and know nothing of lunar disturbance. The extra-tropical belt of +rains and variable weather moves up in its season, uncovering 10 deg., or +more, of latitude, and admitting the trades and a six months' drought over +it, as in California, regardless of the moon. Under the zone of +extra-tropical rains, even upon the eastern part of the continent of North +America, "dry spells" and "wet spells" exist side by side; the focus of +precipitation is now in one parallel, and now in another--_storms_ exist +_here_ and _fair weather there_, on the same continent at the same time; +and as the moon's rays in her northing pass round the northern hemisphere +during the twenty-four hours, they, doubtless, pass from ten to thirty or +more storms, of all characters and intensities, moving in opposition to +her orbit--and as many larger intervening areas of fair weather, not one +of which are indebted to her for their existence, or "take thought of her +coming." + +The storm, which originates in the tropics, pursues its curving way now N. +W., then N. E., and again north, to the Arctic circle, and, perhaps, +around the magnetic pole, over gulf, and continent, and ocean, _occupying +one third the time of a lunation, and two changes, perhaps, in its +progress_, without any perceptible or conceivable influence from her. Yet +every inhabitant of mother-earth, influenced by _coincidences remembered_, +and uninfluenced by _exceptions forgotten_, looks up within his limited +horizon, and devoutly expects from the agency of some phase of the moon, a +change for the special benefit of his _dot_ upon the earth's surface. Upon +how many of these countless dots is the moon at a particular phase, or +relative distance from the sun, to change fair weather to foul, or foul to +fair? Upon none. The storms keep on their way;--the wet spells, and the +dry spells, the cold and the hot spells alternate in their time, and +though the moon turns toward them in passing, her dark face, her half +face, or her full orb (the gifts of the sun, which confer no power), they +do not heed her. They are originated, and are continued, by a more potent +agent. They are the work of an atmospheric mechanism, as _ceaseless_ in +its operation as _time_, as _regular_ as the _seasons_, _as extensive as +the globe_. + +Indeed, it seems as if it was expressly designed by the Creator that the +moon should not interfere materially with this atmospheric machinery. She +is the nearest orb; her influence would be controlling and continuous; +would follow her monthly path from south to north, and with changes too +violent, and intervals too long; and would interfere with the regular +fundamental operation in the trade-wind region, where she is _vertical_. +Aside from the attraction of gravitation, therefore, she seems to have +been so created as to be incapable of exerting any influence. She is +without an atmosphere; the rays which she reflects are polarized, and +without chemical or magnetic power; and, if it be true that Melloni has +recently detected heat in them, by the use of a lens three feet in +diameter, which could not previously be effected, its quantity is +exceedingly small, and incapable of influence. Doubtless, the attraction +of her mass is felt upon the earth, as the tides attest; and upon the +atmosphere as well as the ocean. But the atmosphere is comparatively +_attenuated_, and exceedingly so at its upper surface. Her attraction, +therefore, although felt, is not influential. She seemed, to Dr. Howard, +to produce in her northing and southing, a lateral tide which the +barometer disclosed, but owing to the attenuated character of the +atmosphere, neither the sun nor moon create an easterly and westerly tide, +that is observable, except with the most delicate instruments. Sabine is +believed to have detected such a tide by the barometer, at St. Helena, of +one four thousandth of an inch. But even this _infinitesimal influence_ +may prove an error upon further investigation. There is a diurnal +variation of the barometer, but it is not the result of her attraction, +for it is not later each day as are the tides, exists in the deepest mines +as well as upon the surface, and is demonstrably connected with the +_group_ of _diurnal_ changes produced by the action of the sun-light and +heat upon the earth's magnetism. + +Can the lateral tide, if there be one, affect the weather? for in the +present state of science it seems entirely certain that the moon can exert +an influence in no other way. + +If the received idea of many, perhaps most, meteorologists, on which all +wheel barometers are constructed, that a _high barometer_ necessarily +produces _fair weather_, and a _low one foul_, were true, she certainly +might do so. But that idea can not be sustained, and there is no known +certain influence exerted by the moon upon the weather, in relation to +which we have any reliable practical data. + +Humboldt appears to have adopted the impression of Sir W. Herschell, that +the moon aids in the dispersion of the clouds. (Cosmos, vol. iv. p. 502.) +But the tendency to such dispersion is always rapid during the latter part +of the day and evening, when there is no storm approaching, and the full +moon renders their dissolution visible, and attracts attention to them. +The Greenwich observations, also, carefully examined by Professor Loomis, +fail to confirm the impression of Herschell and Humboldt, and those +eminent philosophers are doubtless in this mistaken. + +From this general and somewhat desultory view of the general facts, which +bear analogically upon the question, no decisive inference can be drawn in +relation to the seat of the primary influence which produces the +atmospheric changes. The preponderance is in favor of the magnetic, or +magneto-electric, action of the earth. We must come back to our own +country and grapple with the question at home. + + + + +CHAPTER IX. + + +Before proceeding to do this, however, it may be well to look at some +theories which have been advanced, and to a greater or less extent +adopted, and at their bearing upon the question. + +The calorific theory is at present the prevailing one in Europe and in +this country. Meteorologists there and here refer all atmospheric +conditions and phenomena to the influence of heat. The principal +applications of that theory have been considered. But within the last few +years the elasticity and tension of the aqueous vapor of the atmosphere +have received much attention, as exerting an auxiliary or modifying +influence. Professor Dove, of Berlin, who ranks perhaps as the most +distinguished meteorologist of that continent, attributes barometric +variations to _lateral overflows_, and, in the upper regions, resulting +from the elevation of the atmosphere by expansion; and in this view +meteorologists of Europe seem generally to acquiesce. In an article sent +to Colonel Sabine, and recently republished in the American Journal of +Science, January, 1855, in thus attempting to account for the annual +variation of barometric pressure, which occurs in Europe and Asia, and, +indeed, over the entire hemisphere. He says: + + "From the combined action or the variations of aqueous vapor, and of + the dry air, we derive immediately the periodical variations of the + whole atmospheric pressure. As the dry air and the aqueous vapor + mixed with it, press in common on the barometer, so that the up-borne + column of mercury consists of two parts, one borne by the dry air, + the other by the aqueous vapor, we may well understand that as with + increasing temperature the air expands, and by reason of its + augmented volume rises higher, and _its upper portion overflows + laterally_," etc. + +And in another place he says: + + "From the magnitude of the variations in the northern hemisphere, and + the extent of the region over which it prevails, we must infer that + _at the time of diminished pressure a lateral overflow probably takes + place_," etc. + +Doubtless, the mean pressure of the atmosphere, in summer, in the northern +hemisphere, is less than in winter, in some localities, and greater in +others, and it differs in different countries of equal temperature. And +this is all very intelligible. The mean of the pressure for the month is +made up by _averaging_ all the _elevations_ and _depressions_. During a +month, showing a very low mean, the barometer may, at times, attain its +_highest altitude_, if the depressions below the mean are great or more +frequent. The barometer is depressed during storms, and ranges high during +_set fair_ weather. Ordinarily, therefore, the more stormy the season the +more diminished the mean pressure; and it is a mistake to look to an +overflow to account for the fact. The changes in the location of the +atmospheric machinery, and consequent change in the amount and severity of +falling weather, and the periodic frequency and character of storms, and +consequent _periodic_ depressions and elevations of the barometer, +explain the annual mean variations, as they do the other phenomena. But it +is perfectly consistent with the calorific theory to attempt to account +for these differences by another of those ever-necessary modifications, +viz.: the different tension and elasticity of aqueous vapor in different +countries of equal temperature; and then to _suppose_ an expansion of the +whole body of the atmosphere and a lateral overflow from the place where +the air is expanded, on to some other, where it is not; and thus _suppose_ +all necessary currents in the upper regions, setting hither and yon, by +the force of gravity alone. And apparently he who is best at supposition +becomes the most distinguished meteorologist. Perhaps I have already said +all that I ought to be pardoned for saying, in relation to the utter +absurdity of attributing all meteorological phenomena to the agency of +heat; but when I find such views as those which that article contains, +emanating from so distinguished a man, sanctioned by the President of the +British Association, and copied into the leading journal of science in +this country, I can not forbear a further and a somewhat critical +examination of them. There is more error of supposition and less truth in +it, than in any other article regarding the science, of equal length, +which has fallen under my notice. + +What is the height of this expansion? The moisture of evaporation ascends, +ordinarily, but a few thousand feet. The atmosphere grows regularly +cooler, from the earth to the trade, and _the increased warmth that is +felt at the surface extends but little way_. Currents of warm air do not +ascend. The strata maintain, substantially, their relative positions; and +this is a most beneficent provision. In northern latitudes of the +temperate zone, all the warmth derived from a few hours' sunshine is +needed at the surface; and, deplorable, indeed, would be our condition, if +the atmosphere, as fast as warmed by the rays of the sun, were to hasten +up, and the frigid strata descend in its place. The earth would not be +habitable. All the warm air on its surface would be rising as soon as it +became warmed, and the cold air above be descending, and enveloping us +with the chilling strata which are ever floating within two or three miles +above us. No. Infinite wisdom has ordered it otherwise. The laws of +magnetism and of static-electric induction and attraction keep the strata +in their places, and preserve to us the warmth which the solar rays afford +or produce. The inhabitant of the valley, in a high northern latitude, in +summer, can plant, and sow, and reap, at the base of the mountain whose +summit penetrates the stratum of continual congelation, and up its sides, +almost to the line of perpetual snow; and, as he looks upon the fruits of +his labor, and up to the snow-clad peak that towers above him, can thank +his Maker for placing a warm equatorial current, a perpetual barrier, +between the fertility and warmth which surround him, and the cold +destructive strata above; and thank Him for not creating such a state of +things, as certain meteorologists insist we shall believe He has created. +Again, where are the _upper regions_, from which the lateral overflow +takes place? The atmosphere is differently estimated, at from thirty to +forty-five miles, or more, in height. Whatever its height may be, it is +exceedingly attenuated in its "upper regions." + +Gay-Lussac marked the barometer at 12-95/100 inches at the height of +23,040 feet. Two thirds of the atmospheric density, then, is within five +miles of the earth. Air, too, is _compressible_. Allowing for the latter +and the attenuation, how many miles in vertical depth, of its "_upper +regions_," must move from one portion to another, to depress the barometer +two inches--its range sometimes in twenty-four hours--or even half an +inch? Let the computation be made, and see how startling the proposition, +how utterly impossible that the theory can be true. + +The distinguished Professor, in the paper referred to, introduces his +theory of the formation of hurricanes, and we quote-- + + "If we suppose the upper portions of the air ascending over Asia and + Africa to flow off laterally, and if this takes place suddenly, it + will check the course of the upper or counter-current above the + trade-wind, and force it to break into the lower current. + + "An east wind coming into a S. W. current must necessarily occasion a + rotatory movement, turning in the opposite direction to the hands of + a watch. A rotatory storm, moving from S. E. to N. W., in the lower + current or trade, would, in this view, be the result of the encounter + of two masses of air, impelled toward each other at many places in + succession, the further cause of the rotation (originating primarily + in this manner) being that described by me in detail in a memoir 'On + the Law of Storms,' translated in the 'Scientific Memoirs,' vol. iii. + art. 7. Thus, it happens that the West India hurricanes, and the + Chinese typhoons occur near the lateral confines on either side of + the great region of atmospheric expansion, the typhoons being + probably occasioned by the direct pressure of the air from the region + of the trade-winds over the Pacific, into the more expanded air of + the monsoon region, and being distinct from the storms appropriately + called by the Portuguese 'temporales,' which accompany the out-burst + of the monsoon when the direction of the wind is reversed." + +The analogy between this, and a theory of Mr. Redfield's, will be noticed +further on. But I remark, in passing, that there is not a fact or +inference in this paragraph which will bear examination. + +1. There is no such regular S. W. wind over the surface trade, as he +supposes. Doubtless, there are, occasionally, secondary S. W. currents +between the counter-trade and the surface one, with partial condensation, +for much of both becomes depolarized by their reciprocal action and +precipitation, and these induced S. W. currents are sometimes so strong as +to usurp the place of the surface-trade, and become very violent in the +latter part of hurricanes; but such is not the usual course of the upper +currents of the West Indies, as the progress of storms there, and +observation, prove. + +2. There can not be any _periods_ of extensive and _sudden_ expansion over +Africa. If there is any place on the earth which has a more uniformly +progressive temperature, either way, and is more free from _sudden_ +extremes, or which is more arid and destitute of aqueous vapor, and sudden +aqueous expansions, than another, it is Africa. No such occasional sudden +expansions are there possible. + +3. Winds do not, and can not, "_encounter_." They stratify upon each +other. They are produced by the action of opposite electricity, and are +_connected together_ in their origin and action. The atmosphere is never +free from the regular and irregular currents, however invisible for the +want of condensation. Aeronauts find them in the most serene days. They +exist without encounter or tendency to rotation, every where, and at all +times; even over the head of the distinguished Professor, whether he +sleeps or is awake. We can all see them when there is condensation, and it +is rarely the case that there is not some degree of it in some of them. + +4. That "Great region of expansion" is a chimera. It does not exist. It is +a region of _lower temperature_, and of _condensation_, instead of +_expansion_ of _aqueous vapor_. The trade does not rise in it, or the S. +W. wind overflow from it. See the table cited page 165. + +5. The hurricanes do not originate _in the surface trades_, as he +supposes. They originate in the belt of rains, the supposed "region of +expansion," and issue out of it; or in the counter-trade, where volcanic +elevations rise far into or above the surface trade. + +6. This hypothesis can not be sustained upon his own principles. The +distance between Africa and the West India Islands, where most of the +hurricanes originate, is from 2,500 to 3,000 miles. These gales are small +when they commence, not ordinarily over one or two hundred miles in +diameter, and often less. There are trades all the way over from Africa, +and S. W. winds also, if they exist, as he supposes, in the West Indies. +How can it happen that this lateral overflow should pass _without effect_, +over 2,500 miles of S. W. wind and trade, and concentrating the overflow +of a continent over one small and chosen spot of the West Indies, _pitch +down_ there, and there only, and crowd the S. W. wind into the trade +below? This is too much for sensible men to believe. + +What does Professor Dove mean by the term _impulsion_, as applied to the +winds? How are they _impelled_? It is the fundamental idea of his +calorific theory, that they are _drawn_ by the _suction_ caused by a +_vacuum_, and the vacuum created by expansion and overflow above, in +obedience to the law of gravity; that the S. E. trade is drawn to the +great region of expansion, and the S. W. runs from it as an overflow. But +if the S. W. is driven down into the plane and place of the +surface-trades, how does it continue to be impelled, and why is it not +then subject to the suction of the vacuum which draws the trade? Does that +vacuum _select its air_, and so attract the trade, in preference to the +depressed portion of the S. W. current, that the former runs around the +latter to get to the vacuum, and the latter around the former to get away +from it? And does the trade, when it has got around the S. W. current, +instead of going to the vacuum, continue to gyrate, and the S. W. current, +instead of pursuing its regular course, gyrate also about the trade, and +both move off together, regardless of the vacuum of the great region of +expansion, in a new direction to the N. W., in an independent, +self-sustaining, cyclonic movement, increasing in power and extent, +involving extended and increasing condensation, producing the most violent +electrical phenomena, and thus continuing up, even to the Arctic circle? +Yes, says Professor Dove. No, say all fact, all analogy, and his own +principles. + +7. His theory relative to the typhoons is unintelligible. If they +originate near the lateral confines of the great region of atmospheric +expansion, they originate in the region of the trade-winds, for the two +are identical. How the direct pressure of the air from the trade-wind over +the Pacific, in the more expanded air of the monsoon region, can occasion +a typhoon upon any principles, passes my comprehension. If, as Lieutenant +Maury supposes, the monsoons are reversed trades, then the trade-wind and +monsoon region are identical. If the monsoons are found in the belt of +rains, then, the trades, upon Professor Dove's principles, pass into the +monsoon region by attraction or suction, without pressure. Either way the +theory is undeserving of consideration. + +A new theory has recently been started by Mr. Thomas Dobson, and, although +it is (like all other efforts to get the _upper strata down_ to produce +condensation, or those below _up_, that they may be condensed), without +foundation, his collection of facts is brief and interesting. I copy his +article from the London, Edinburgh, and Dublin Phil. Mag., for December, +1853. It adds to the collection of facts in relation to the connection +between volcanic action and storms for the seventeenth century, made by +Dr. Webster: + + The following appear to be the main facts which are available as a + basis for a theory which shall comprehend all the meteors in + question: + + 1st. The eruption of a submarine volcano has produced water-spouts. + + "During these bursts the most vivid flashes of lightning continually + issued from the densest part of the volcano, and the volumes of smoke + rolled off in large masses of fleecy clouds, gradually expanding + themselves before the wind in a direction nearly horizontal, and + drawing up _a quantity of water-spouts_."--(Captain Tilland's + description of the upheaval of Sabrina Island in June, 1811, Phil. + Trans.) + + With this significant fact may be compared the following analogous + ones: + + "In the Aleutian Archipelago a new island was formed in 1795. It was + first observed _after a storm_, at a point in the sea from which a + column of smoke had been seen to rise."--(Lyell, Principles of + Geology.) + + "Among the Aleutian Islands a new volcanic island appeared in the + midst of _a storm_, attended with flames and smoke. After the sea was + calm, a boat was sent from Unalaska with twenty Russian hunters, who + landed on this island on June 1st, 1814."--(Journal of Science, vol. + vii.) + + "On July 24th, 1848, a submarine eruption broke out between the + mainland of Orkney and the island of Strousa. Amid thunder and + lightning, a very dense jet black cloud was seen to rise from the + sea, at a distance of five or six miles, which _traveled toward the + north-east_. On passing over Strousa, the wind from a slight air + became _a hurricane_, and a thick, well-defined belt of large + hailstones was left on the island. The barometer fell two + inches."--(Transactions Royal Society, Edinburg, vol. ix.) + + 2d. Hurricanes, whirlwinds, and hailstones accompany the paroxysms of + volcanos. + + "1730. A great volcanic eruption at Lancerote Island, and _a storm_, + which was equally new and terrifying to the inhabitants, as they had + never known one in the country before."--(Lyell, Principles of + Geology, vol. ii.) + + "1754. In the Philippine Islands a terrible volcanic eruption + destroyed the town of Taal and several villages. Darkness, + hurricanes, thunder, lightning, and earthquakes, alternated in + frightful succession."--(Edinburgh Philosophical Journal.) + + "In 1805, 1811, 1813, and 1830, during eruptions of Etna, caravans in + the deserts of Africa perished by violent whirlwinds. In 1807, while + Vesuvius was in eruption, a whirlwind destroyed a caravan."--(Rev. W. + B. Clarke in Tasw. Journal.) + + "1815, Java. A tremendous eruption of Tombow Mountain. Between nine + and ten P.M., ashes began to fall, and soon after _a violent + whirlwind_ took up into the air the largest trees, men, horses, + cattle, etc."--(Raffles' History of Java.) + + "1817, Dec. Vesuvius in eruption. In the evening _a hail storm_, + accompanied with red sand."--(Journal of Science, vol. v.) + + "1820, Banda. A frightful volcanic eruption, and in the evening an + earthquake and a violent hurricane."--(Annales de Chimie.) + + "1822, Oct. Eruption of Vesuvius. Toward its close the volcanic + thunder-storm produced an exceedingly violent and abundant fall of + rain."--(Humboldt, Aspects of Nature.) + + "1843, Jan. Etna in eruption. Violent hurricanes at Genoa, in the Bay + of Biscay, and in Great Britain. + + "1843, Feb. Destructive earthquakes in the West Indies, a volcanic + eruption at Guadaloupe, followed by hurricanes in the Atlantic." + + "1846, June 26. Volcano of White Island, New Zealand, in eruption. + Heavy squalls of wind and hail; it blew as hard as in a + typhoon."--(Commodore Hayes, R.N., in Naut. Mag., 1847.) + + "1847, March 20. Volcanic eruption and earthquake in Java; and on the + 21st of March, and 3d of April, violent hurricanes."--(Java Courant.) + + "1851, Aug. 5. A frightful eruption of the long dormant volcano of + the Pelee Mountain, Martinique. Aug. 17. Hurricane at St. Thomas, + etc.; earthquake at Jamaica, etc. + + "1852, April 14. Earthquake at Hawaii, and on the 15th a great + volcanic eruption. On the 18th _a gale of unusual violence_ lasted + thirty-six hours, and did great damage."--(The Polynesian, April 22, + 1852.) + + 3d. In volcanic regions, earthquakes and hurricanes often occur + almost simultaneously, but in no certain order, and without any + volcanic eruption being observed. + + In 1712, 1722, 1815, and 1851, earthquakes and hurricanes occurred + together at Jamaica; in 1762 at Carthagena; in 1780 at Barbadoes; in + 1811 at Charleston; in 1847 at Tobago; in 1837 and 1848 at Antigua; + in 1819, an awful storm at Montreal, rain of a dark inky color, and a + slight earthquake. People conjectured that a volcano had broken out. + In 1766 the great Martinique hurricane, a _waterspout_ burst on Mount + Pelee and overwhelmed the place. Same night, an earthquake. + + 1843, Oct. 30. Manilla.--Twenty four hours' rain and two heavy + earthquakes. 10 P.M., a severe hurricane. + + "1852, Sept. 16. Manilla--An earthquake destroyed a great part of the + city; many vessels wrecked by a great hurricane in the adjacent seas, + between the 18th and 26th of September."--(Singapore Times.) + + "1731, Oct. Calcutta.--Furious hurricane and violent earthquake; + 300,000 lives lost." + + "1618, May 26. Bombay.--Hurricane and earthquakes; 2,000 lives + lost."--(Madras Lit. Tran., 1837.) + + "1800. Ongole, India, and in 1815, at Ceylon, a hurricane and + earthquake shocks."--(Piddington.) + + "1348. Cyprus.--An earthquake and a frightful hurricane."--(Hecker.) + + "1819. Bagdad.--An earthquake and _a storm_--an event quite + unprecedented. + + "1820, Dec. Zante.--Great earthquake and hurricane, with + manifestations of a submarine eruption."--(Edinburg Phil. Journal.) + + "1831, Dec. Navigator's Islands.--Hurricane and + earthquakes."--(Williams' Missionary Enterprise.) + + "1848, Oct., Nov. New Zealand.--Succession of earthquake shocks, and + several tempests. + + "1836, Oct. At Valparaiso, a destructive tempest and severe + earthquakes."--(Nautical Magazine, 1848.) + + When an earthquake of excessive intensity occurs, as at Lisbon, in + 1755, the volcanic craters, which act as the safety-valves of the + regions in which they are placed, are supposed to be sealed up; and + it is a remarkable and highly-suggestive fact, that _no hurricane + follows such an earthquake_. The number of instances of the + concurrence of ordinary earthquakes and hurricanes might easily be + increased, but the preceding suffice to show the _generality_ of + their coincidence, both as _to time_ and place. + + 4th. The breaking of water-spouts on mountains sometimes accompanies + hurricanes. + + In 1766, during the great Martinique hurricane, before cited. + + "1826, Nov. At Teneriffe, enormous and most destructive water-spouts + fell on the culminating tops of the mountains, and a furious cyclone + raged around the island. The same occurred in 1812 and in + 1837."--(Espy and Grey's Western Australia.) + + "1829. Moray.--Floods and earthquakes, preceded by water-spouts and a + tremendous storm."--(Sir T. D. Lander.) + + "1826, June. Hurricanes, accompanied by water-spouts and fall of + avalanches, in the White Mountains."--(Silliman's American Journal, + vol. xv.) + + 5th. The fall of an avalanche sometimes produces a hurricane. + + "1819, Dec. A part (360,000,000 cubic feet) of the glacier fell from + the Weisshorn (9,000 feet). At the instant, when the snow and ice + struck the inferior mass of the glacier, the pastor of the village of + Randa, the sacristan, and some other persons, _observed a light_. A + frightful hurricane immediately succeeded."--(Edinburg Philosophical + Journal, 1820.) + + 6th. Water-spouts occur frequently near active volcanos. + + This is well known with regard to the West Indies and the + Mediterranean. The following notices refer to the Malay Archipelago + and the Sandwich Islands: + + "Water-spouts are often seen in the seas and straits adjacent to + Singapore. In Oct., 1841, I saw _six_ in action, attached to one + cloud. In August, 1838, one passed over the harbor and town of + Singapore, dismasting one ship, sinking another, and carrying off the + corner of the roof of a house, in its passage landward."--(Journal of + Indian Archipelago.) + + "1809. An immense water-spout broke over the harbor of Honolulu. A + few years before, one broke on the north side of the island (Oahu), + washed away a number of houses, and drowned several + inhabitants."--(Jarves' History of Sandwich Islands.) + + 7th. Cyclones begin in the immediate neighborhood of active volcanos. + + The Mauritius cyclones begin near Java; the West Indian, near the + volcanic series of the Caribbean Islands; those of the Bay of Bengal, + near the volcanic islands, on its eastern shores; the typhoons of the + China Sea, near the Philippine Islands, etc. + + 8th. Within the tropics, cyclones move toward the west; and, in + middle latitudes, cyclones and water-spouts move toward the N. E., in + the northern hemisphere, and toward the S. E. in the southern + hemisphere. + + 9th. In the northern hemisphere, cyclones rotate in a horizontal + plane, in the order N. W., S. E.; and in the southern hemisphere, in + the order N. E., S. W. + + By applying the principles of electro-dynamics to the electricity of + the atmosphere, I shall endeavor to connect and explain the preceding + well-defined facts. The continuous observations of Quetelet, on the + electricity of the atmosphere, from 1844 to 1849 (Literary Journal, + February, 1850), show that it is always positive, and increases as + the temperature diminishes. It therefore increases rapidly with the + height above the earth's surface. We may, consequently, regard the + upper and colder regions of the atmosphere as an immense reservoir of + electric fluid enveloping the earth, which is insulated by the + intermediate spherical shell formed by the lower and denser + atmosphere. Now, whenever a vertical column of this atmosphere is + suddenly displaced, the surrounding aqueous vapor will be immediately + condensed and aggregated, and the cold rarefied air and moisture will + form a vertical conductor for the descent of the electrical fluid. + This descent will take place down a spiral, gyrating in the order N. + W., S. E., in the northern hemisphere, since the electric current is + under the same influence as that of the south pole of a magnet; and + in the order N. E., S. W., in the southern hemisphere. The air + exterior to the conducting cylinder will partake of the violent + revolving motion, and a tornado or cyclone will be produced. + +Upon the foregoing facts I shall comment in another place. + +Three theories have been advanced by meteorologists of this country, two +of which profess to explain all the phenomena of the weather. Professor +Espy attributed the production of storms and rain to an ascending column +of air, rarefied by heat, and the rarefaction increased by the latent heat +of vapor given out during condensation, and an inward tendency of the air, +from all directions, toward the ascending vortex, constituting the +prevailing winds. Thus, Professor Espy conceived, and to some extent +proved, that the wind blew inward, from all sides, toward the center of a +storm, either as a circle, or having a long central line, and he conceived +that it ascended in the middle, and spread out above; and that clouds, +rain, hail, and snow, were formed by condensation consequent upon the +expansion and cooling of the atmosphere, as it attained an increased +elevation. + +_This ascent_ was not, in fact, _proved_ by Professor Espy, _has not been +found by others_, and _is not discoverable, according to my observations_. +The theory was ingenious, founded on the theory of Dalton, that the vapor +was maintained in the atmosphere by reason of a large quantity of latent +heat, which was given out when condensation took place. This theory is +also unsound. No such elevation of temperature is found in clouds or fogs +when they form near the earth, however dense. Thus the two principal +elements of Professor Espy's theory are found to be untrue, and the theory +untenable. But it was sustained with great ability and research, and the +distinguished theorist deserves much for the discovery and record of +important facts in relation to the weather. Aside from its theoretical +views, his book contains a great mass of valuable information, and will +well repay the cost of purchase and perusal. + +Another theory, by Mr. Bassnett, is of recent date, founded on the +influence of the moon, and the supposed creation of vortices in the ether +above, whose influence extends to the earth, producing storms and other +phenomena. No one can peruse his book without conceding to him great +ability and scientific attainment; and if his theory was true, the periods +of fair and foul weather could be calculated with great mathematical +certainty. But it contains inherent and insuperable objections. I will +only add that all herein before contained is in direct opposition to it. + +Mr. W. C. Redfield, of New York, as early as 1831, first advanced in this +country the theory of gyration in storms, and investigated their lines of +progress on our coast and continent. His theory is limited in its +character, and does not profess, except indirectly, to explain all, or +indeed any, of the other phenomena of the weather. As far as it goes, +however, it is generally received in this country and Europe, and has +been adopted by Reed, Piddington, and others, who have written on the law +of storms. The position of Mr. Redfield is honorable to himself and his +country. Science and navigation are much indebted to him for his industry +in the collection of facts. Nevertheless, his theory is not in accordance +with my observation, and I deem it unsound. Although expressed disbelief +of the theory has been characterized as an "attack" upon its author, I +propose, with that _respect_ which is due to him, but with that _freedom_ +and _independence_ which a search for _truth_ warrants, to examine it with +some particularity. It is a part of the subject, and I can not avoid it. + +When the theory was first announced, I adopted it as probably true; and +being then engaged in a different profession, which took me much into the +open air by night and day, I watched with renewed care the clouds and +currents for evidence to confirm it. I discovered none; on the contrary, I +found much, very much, absolutely and utterly inconsistent with its truth. +The substance only of these observations will be adduced. + +Mr. Redfield admits that the progression of our storms in the vicinity of +New York, is from some point between S. S. W. and W. S. W., to some point +between N. N. E. and E. N. E. According to my observation, except perhaps +in occasional autumnal gales, they are not often, if ever, from S. of S. +W., and the great majority of them, including, I believe, all N. E. +storms, are between S. W. and W. S. W. Now, the card of Mr. Redfield, +moving over any place from any point between S. W. and W. S. W., calls for +a S. E. wind at its axis, an E. wind at its north front, and a S. wind at +its south front, and does not call _for a N. E. wind on its front at all, +except at the north extreme_, where it could _not continue for any +considerable period_. + + +[Illustration: Fig. 17.] + + +In relation to this, I observe, 1st. _About one-half of our N. E. storms, +including some of the most severe ones, not only set in N. E., but +continue in that quarter without veering at all, during the entire period +that the storm cloud is over us_; usually for twenty-four hours; not +unfrequently for forty-eight hours, sometimes for seventy-two or more +hours. This every one can observe for himself, and it can not, of course, +be reconciled with his theory. + +2d. N. E. storms, whether they set in from that quarter in the +commencement, or veer to it afterward, when they do "change" round, more +frequently veer by the S. to the S. W. in clearing off, than back through +the N. into the N. W. The former, in accordance with his theory, they can +not do, as the reader can see by passing the left side of the card over +his place of residence on the map from S. W. to N. E. + +3d. N. E. storms often pass off without hauling by S. or backing by N., +and with or without a clearing off shower, the _wind shifting and coming +out suddenly at S. W._ This they could not do in accordance with his +theory, as slipping the card will show. + +4th. From June to February it is _exceedingly uncommon_ for a N. E. storm +to back into the N. W. They do so more frequently from February to May, +especially about the time of the vernal equinox and after; and then, +because the focus of precipitation and storm intensity of the extra +tropical zone of rains is S. of 42 deg. east of the Alleghanies. His theory +requires them to back by N. into N. W. _in all cases, when they set in N. +E._ + +5th. When they do back from the N. E. into the N. W., it rarely indeed +continues to storm after the wind leaves the point of N. E. by N., and +generally, if it does continue stormy, _the wind is light_, and not a +gale, how violent soever the gale from the eastward may have been. +Usually, by the time the wind gets N. W., it has cleared off. This, Mr. +Redfield, as we shall see, evades by embracing the N. W. fair wind as a +part of the same gale. According to my observation, therefore, a _very +large proportion_ of the _N. E. storms_, and they are a majority of the +most violent ones of our climate east of the Alleghanies, do not +_commence, continue_, or _veer_ in accordance with his theory, but the +_reverse_; and so long as this is so, I can not receive his theory as +true. + +6th. S. E. storms do not always, or indeed often, conform to the +requirements of his card. When they set in violently at S. E., and +continue so for hours without veering, the axis of the storm should be +over us, and the wind should change _suddenly_ to N. W. This did not occur +in the storm of Sept. 3, 1821, nor does it often, if ever, occur in the +summer or early gales of the autumnal months. In the later storms of +autumn, and as often in those which are very gentle as any, and in the +winter months when S. E. gales are rare, it does sometimes so change after +the storm cloud has passed. But in the winter months, as in the storm +investigated by Professor Loomis, the storms are frequently long from S. +E. to N. W., and the S. E. wind blows nearly in coincidence with its long +axis, for a thousand or fifteen hundred miles, till the barometric minimum +is passed, and the inducing and attracting force of this part of the storm +cloud is spent, and then the N. W. wind follows; sometimes blowing in +under the storm cloud, turning the rain to snow; but oftener following the +storm within a few hours, or the next day. The storm of Professor Loomis, +when over Texas, was not probably more than four or five hundred miles in +length. As it curved more, and passed north and east, it extended +laterally, its center traveling with most rapidity, and when it reached +the eastern coast was about fifteen hundred miles long, and not more than +six hundred broad. Along the eastern part of that storm, except when by +its more rapid progress the front projected much further eastward over New +England than its previously existing line, the S. E. winds blew. When it +bulged out, so to speak, by reason of the increased progress of the +center, the wind veered to the N. E. The center of the storm passed near +St. Louis and south of Quebec, as the _fall of rain_, the _bulging_ of the +_rapidly-moving center_, and the _line of subsequent cold_, attest. It is +utterly impossible for any unbiased mind to look at the description of +that storm, and attribute to it a rotary character. With all the data +before him, Mr. Redfield himself has not attempted it directly.[8] + +The September storm of 1821 was more violent in character than any which +have since occurred. My recollection of it is as distinct as if it +occurred yesterday. Peculiar circumstances, not important in this +connection, fixed my attention upon the weather during that day and night. +There were cirro-stratus clouds passing all day, from about S. W. to N. +E., thickening toward night with fresh S. S. W. wind and flocculent scud, +such as I have since seen at the setting-in of S. E. autumnal gales. In +the evening the wind (in the immediate neighborhood of Hartford, Ct.), +veered to S. E., the cloud floated low, it became very dark, and the wind +blew a most violent gale. The trees were falling about the house where I +then resided, the windows were burst in, and I was up and observant. When +the cloud passed off to the east, it was suddenly light, and almost calm. +The western edge of the storm cloud was as perpendicular as a steep +mountain side, and was enormously elevated, and very black. I have +sometimes seen the western side of a summer thunder cloud, which had drawn +a violent gust along beneath it, as elevated and perpendicular, but never +a storm cloud. No cloud of that _depth_, or _intensity_ as exhibited by +its peculiar blackness, ever floated or will float so near the earth, +without inducing a devastating current beneath. After it had passed the +ridges east of the Connecticut valley, its top could be seen for a long +and unusual period over the elevated ranges. + +Now that storm was but an _intense portion_ of an extensive stratus-rain +cloud. Such portions frequently exist, and Mr. Redfield admits the fact. +Another like portion, in the same storm, passed over Norfolk, Virginia, +and the adjacent section, where the wind was N. E., and veered round by N. +W. to S. W. Baltimore, and some vessels at sea, were between the two +intense portions of the storm, and were not affected by either. Its +northern limit was bounded by a line, drawn from some point not far north +of Trenton, New Jersey, north-eastward, and north of Worcester, +Massachusetts. I was about forty miles south of its northern limit, and +north of its center. During that day, and the next, there was wind from +S. W. to S. E., inclusive, including the gale, and _from no other +quarter_. It did not at any time veer to the W. or N. W. After the passage +of the storm-cloud, the wind was very light. When this intense portion of +the storm passed over the valley of the Connecticut, its longest axis was +from S. S. E. to N. N. W., and the _wind was S. E. the whole length of +it_. In its passage from the longitude of Trenton to Boston, there was N. +W. wind at one point, and but one, and that was in the iron region, at the +N. W. corner of Connecticut, at the northern limit of the intense cloud, +and owing, doubtless, to some local cause. The direction of the wind in +that storm was in accordance with what is generally true of our storms. +The wind on the front of the storm depends upon its shape. If the storm is +long in proportion to its width (and no other _violent_ autumnal or winter +storm has been investigated, to my knowledge), the wind blows axially, or +obliquely, on its front. Thus, if long from S. E. to N. W., the wind on +its front will blow from the S. E. So, if the storm is long from S. W. to +N. E., and has a south-eastern lateral extension, with an easterly +progression, the wind will blow axially in the center, and obliquely at +the edges. Instances might be multiplied, but I refer to one of recent +date and striking character. All of us remember the drought of 1854. It +ended in drenching rain on the 9th of September. This rain fell from a +belt, half showery and half stormy in character, which had a S. E. lateral +extension. + +The evening of the previous day there was some lightning visible at the +north, and the usual S. S. W. afternoon wind _continued fresh after +nightfall_. The next day we had a brisk wind from the same quarter, and, +after noon, the clouds appeared to pile up in the far north, seeming very +elevated. They continued to do so, extending southerly during the +afternoon, _with a high wind from S. S. W._, the cumulus clouds moving E. +N. E. At 5 P.M., gentlemen who left New York at 3 P.M., reported that a +dispatch had been received from Albany, dated 1 P.M., stating that it was +raining very heavily there. About 7 P.M., the belt reached us, and it +rained heavily from that time till morning. Not far from 8 P.M., and +during the heaviest rain, the wind shifted from the S. S. W. to N. E., and +blew fresh and cold from that quarter during the night, and till the belt +had passed south, and then from N. E. by N., cool, with heavy scud, during +the forenoon, veering gradually to the N. N. E., and dying away. After the +rain ceased, the northern edge of the belt was distinctly visible in the +S. and S. E., its stratus-cloud moving E. N. E., and its scud to the +westward. + +The front of that storm did not pass over us. It was long and narrow. The +wind blew somewhat obliquely inward, along its southern border, to the +eastward, and, in like manner, to the westward, on its northern border, +but from the N. E. axially along its central portions. + +In the last instance, the wind changed from S. W. to N. E. This, too, is +impossible, according to Mr. Redfield's theory. Similar instances, in +summer, and early autumn, are not uncommon. But I shall recur to this in +connection with the different _classes_ of storms. + +Again, the manner in which these S. E. winds co-exist with the N. E., and +become the prevailing wind, toward the close of the storm, is instructive, +and inconsistent with the theory of Mr. Redfield. In the West Indies, the +first effect of the storm is to increase the N. E. trade; the wind then +becomes baffling, but settles in the N. W. or N. N. W., _in direct +opposition to the admitted progress of the storm_. At this point, or at S. +W., it blows with most force. Sometimes it veers gradually, and sometimes +falls calm, and comes out from the S. W., blowing violently. It ends by +veering to the S. E., following gently the course of the storm. Thus, Mr. +Edwards, in the third volume of his History of Jamaica, as herein before +cited, "_all hurricanes begin from the north, veer back to W. N. W., W., +and S. S. W., and when they get round to S. E. the foul weather breaks +up_." + +A short, sudden gale, resembling those of our summer thunder-showers, is +sometimes met with from the S. E.; but the violent hurricanes of any +considerable continuance are, in almost every case, as just stated. + +Now, there is, in our latitudes, an obvious law on the subject, and it is +this:--If the storm is not disproportionately long, northerly and +southerly, there is a general tendency to induce and attract a surface +current, in opposition to the course of the storm on its front, and +especially its north front. At the same time, there is a tendency to +induce a lateral current on its side, particularly the southerly side, and +sometimes its south front: that the latter current is, in the first part +of the storm, above the former; in the middle and latter part, it becomes +the prevailing current at the surface, and the wind changes accordingly, +with or without a calm--that this lateral change sometimes takes place on +either side, but usually occurs on the side where the water is warmest, or +there is, for other and local reasons, a _greater susceptibility in the +atmosphere to inductive and attractive influence_. Thus, our N. E. storms +very frequently have a southerly current also, drawn from the ocean, south +of us, which forms the middle current, and, in the middle and latter part +of it, becomes the prevailing one. _I have seen more than a hundred such +instances, clearly and distinctly marked._ Since I have been writing this +chapter, January 29th, 1855, such an instance has occurred. On Sunday, the +28th, the cirro-stratus were all day passing from the S. W. to N. E., and +gradually thickening with light air from the E. N. E., in the afternoon. +During the evening the wind set in _violently_ from the N. E., with a +deluging rain. During the night, and after a brief calm, it changed +suddenly to the southward, and blew in like manner. This morning the storm +was gone, and with it, six inches of hard, frozen icy snow; the trade was +clear, with the exception of here and there a broken, melting piece of +stratus, but scud were still running from the southward, and the wind has +been from the south, veering to S. W., all day, with sunshine. As I have +before remarked, this middle current is always present, in this locality, +in stratus storms, when there is a heavy fall of rain or snow, although, +when the latter happens, the middle current is sometimes from the +northward; if it be from the southward, it turns the snow first into very +large flakes, and then to rain in our part of the storm. + +Doubtless, the same thing occurs every where. In the West Indies, and +especially over the Leeward Islands, the middle current is most commonly +from the stream of warm water which runs off to the westward into the +Caribbean Sea; as the S. W. moonsoon is from the same current below the +Cape de Verdes. The S. W. winds, which come from those south polar waters, +in the West Indies, appear to be the most violent. But it may be on either +or both sides. + +The hurricane cloud of the West Indies moves confessedly N. W. in most +instances, and undoubtedly it does in all. There is an immutable law that +requires it. The seeming exceptions are not such; they are but instances +imperfectly investigated. Now, a circular storm moving N. W. can set in N. +W. only on the left front, and _can not change to S. W. on that side of +the axis_. Nor can the wind blow at the axis from N. W. at all. It should +be N. E. in first half, and S. W. in last half. Strange as it may seem, +the axis of a West India hurricane in conformity with Mr. Redfield's +theory, and a N. W. progression, has never been found, with perhaps a +single exception, in any one of which I have seen a description. On the +west coast of Europe, the gale is commonly from the Atlantic, either +following under the storm from the S. W., or blowing in diagonally from +the W. or N. W.; the N. E. wind of western Europe being a cold, dry wind, +which there is reason to believe has been around the Siberian pole and is +returning, as the cold northerly winds of the North Pacific have around +the North American magnetic pole. "If the N. E. winds always prevailed," +says Kaemtz, speaking of Berlin, "even at a considerable height it would +never rain." This was based on an observation of showers, and not fully +reliable. But the dry and cool character of the N. E. wind of western +Europe is unquestionable. The S. E. wind is also a storm wind, but owing +to the character of the surface from which it is attracted, it is not as +violent as the westerly winds are. + +Such, too, is the general course and character of the side wind in the +southern hemisphere. There gales are less frequent, the magnetic intensity +is less, the counter-trades are less; it is not in "the order of +Providence" that as much rain shall fall there. Nevertheless, gales occur, +although rarely, if ever, with equal violence. About New Holland, where +storms are pursuing a S. E. course, they have the wind N. E., +corresponding to our S. E., veering from thence, _by the north_, to the +westward, clearing off from S. W., with a rising barometer, as ours do +from N. W. + +In the Bay of Bengal, the Indian Ocean, and the Arabian Sea, there is more +irregularity. + +But the law of progress and lateral winds can be distinctly traced as +_present_ and prevailing, notwithstanding the irregularities. Our limits +do not permit an analysis. In the celebrated case of the Charles Heddle, +there was much evidence to show that she was driven across the front of +the storm by one lateral wind, and back by another. (Diagram of Colonel +Reid, p. 206.) + +The waters of the Indian Ocean are hot and confined. Storms there are +often composed of detached masses, move slower--sometimes not more than +three or four miles an hour--and they curve over the ocean, where it is +hotter than in any similar latitude. Yet, notwithstanding all +peculiarities and irregularities, the law we have been considering is +probably the _prevailing_ law there. + +No man knows better the existence of these different currents than Mr. +Redfield. Doubtless it has escaped his attention that the upper of two, +after the passage of a considerable proportion of the storm, becomes the +lower, and causes a seeming change of the same wind. + +In a series of elaborate articles, substantially reviewing the whole +subject, published in the American Journal of Science, for 1846, he says: + + "In nearly all great storms which are accompanied with rain, there + appear two distinct classes of clouds, one of which, comprising the + storm scuds in the active portion of the gale, has already been + noticed. Above this is an extended stratum of stratus cloud, which is + found moving with the general or local current of the lower + atmosphere which overlies the storm. It covers not only the area of + rain, but often extends greatly beyond this limit, over a part of the + dry portion of the storm, partly in a broken or detached state. This + stratus cloud is often concealed from view by the nimbus, and scud + clouds in the rainy portion of the storm, but by careful + observations, may be sufficiently noticed to determine the general + uniformity of its specific course, and, approximately, its general + elevation. + + "The more usual course of this extended cloud stratum, in the United + States, is from some point in the horizon between S. S. W. and W. S. + W. Its course and velocity do not appear influenced in any + perceptible degree by the activity or direction of the storm-wind + which prevails beneath it. On the posterior or dry side of the gale, + it often disappears before the arrival of the newly condensed cumuli + and cumulo-stratus which not unfrequently float in the colder winds, + on this side of the gale." + + "The general height of the great stratus cloud which covers a storm, + in those parts of the United States which are near the Atlantic, can + not differ greatly from one mile; and perhaps is oftener below than + above this elevation. This estimate, which is founded on much + observation and comparison, appears to comprise, at the least, the + limit or thickness of the proper storm-wind, which constitutes the + revolving gale. + + "It is not supposed, however, that this disk-like stratum of + revolving wind is of equal height or thickness throughout its extent, + nor that it always reaches near to the main canopy of stratus cloud. + It is probably higher in the more central portions of the gale than + near its borders, in the low latitudes, than in the higher, and may + thin out entirely at the extremes, except in those directions where + it coincides with an ordinary current. Moreover, in large portions of + its area, there may be, and often is, more than one storm-wind + overlying another, and severally pertaining to contiguous storms. In + the present case, we see, from the observations of Professor Snell + and Mr. Herrick, at Amherst, Massachusetts, and at Hamden, Maine (115 + and 135 b.), that the true storm wind, at those places, was + super-imposed on another wind; and various facts and observations may + be adduced to show that brisk winds, of great horizontal extent, are + often limited, vertically to a very thin sheet or stratum." + +Much of the foregoing is graphically described, and unquestionably true. +But it may well be asked how he, or others, distinguish which of two or +more currents (for there are frequently three, and sometimes four +visible), are the true currents of the storm, and which interlopers from +another storm? Is the true one always the upper one, and why? If the +upper one, why is the interloper at the surface noted and quoted to prove +what a storm is? How does he know what proportions of the winds he has +recorded to show the revolving motion of gales, were the true storm winds +of the particular storm? or, that every one of them was not an interloping +wind on which the true storm wind was superimposed? + +These inquiries are pertinent, for obviously, unless some rule for +distinguishing between the currents is given, and there be evidence of +direct observation to show that the surface wind, whose direction is +noted, is the true wind of the storm, and that the _latter_ is not +_superimposed_, no reliance can be placed upon logs, or newspaper +accounts, or registers. There is another element besides direction, viz.: +superimposition, a determination of which _is_ essential to _truth_. It +will be difficult for Mr. Redfield to say that a determination of that +element has been made, with certainty, in a single storm he has +investigated; and in relation to the convergence of storms, and blending, +and superimposition of their winds, I think he is mistaken. + +Mr. Redfield is right in saying (American Journal of Science, vol. ii., +new series, p. 321) that "too much reliance may be placed upon mere +observations of the surface winds in meteorological inquiries," and yet +_they_ only have thus far been regarded, and he has proved gyration in no +other way. I have frequently, with a vane in sight, asked intelligent men +how the wind was, and been amused and instructed by their inability to +state it correctly. Mr. Redfield, in his inquiries, often found two +reports of the weather at the _same time_, from the _same place_, +materially different; and I have known, from my own observation, +newspapers and meteorological registers to be several points out of the +way; and this, because the vanes are influenced by local elevations, and +change several points, and very often; because few know the exact points +of the compass in their own localities, and because entire accuracy has +not been deemed essential. For these reasons, newspaper and telegraphic +reports are not always reliable; and therefore, and because, also, +storm-winds are easterly and fair winds westerly, and the former veer from +east around to west, on one or both sides in many cases, there are few +storms which can not be represented as whirlwinds, by a proper _selection_ +of _reports_, a corresponding _location_ of the _center_, and an +_extension_ of the lines of supposed gyration, so as to include the +_preceding_ winds, the actual winds of the storm, and the _lateral_, and +_succeeding_ fair weather ones. + +But, again, Mr. Redfield is right in saying there is, in such cases, "an +extended stratum of stratus cloud," and it is always present. But why does +he say this _covers the storm_? Is it distinct from it, and if so, what is +it doing there? What power placed it there, and for what purpose? Has this +extended stratum of cloud, which forms the canopy of a vast chamber--five +hundred to one thousand miles in diameter, and less than two miles in +vertical depth, while the earth forms the floor--any agency in producing +the whirl that is supposed to be going on within it, and if so, what? Has +the earth any agency, and if so, what? If neither the ceiling nor floor of +the chamber have any agency in producing it, what does? Are we to consider +the _storm-scud_ as possessing the power, and as waltzing around the +aerial chamber, carrying the air with them in a hurricane-dance of +devastation? _What, in short, is the power, and how is it exerted?_ + +To these questions, Mr. Redfield's essays furnish no comprehensive answer. +There is an intimation that the cause of storms will be, at some future +day, developed. One attempt, and but one, has thus far been made, and that +I quote entire: + + "We have seen that the two Cuba storms, as well as the Mexican + northers, have appeared to come from the contiguous border of the + Pacific Ocean. + + "Now, are there any peculiarities in the winds and aerial currents of + those regions, which may serve to induce or support a leftwise + rotation in extensive portions of the lower atmosphere, while moving + on, or near the earth's surface? I apprehend there are such + peculiarities, which have an extensive, constant, and powerful + influence. First, we find on the eastern portion of the Pacific, from + upper California to near the Bay of Panama, an almost constant + prevalence of north-westerly winds at the earth's surface. Next, we + have an equally constant wind from the southern and south-western + quarter, which, having swept the western coast of South America, + _extends across the equator to the vicinity of Panama_, thus meeting, + and commonly over-sliding the above-mentioned westerly winds, and + tending to a deflection or rotation of the same, from right to left. + As this influence may thus become extended to the Caribbean or + Honduras Sea, we have, next, the upper or S. E. trade of this sea, + which is here frequently a surface-wind, and must tend to aid and + quicken the gyrative movement, ascribed to the two previous winds; + and lastly we have the N. E. or lower trade, from the tropic, which, + coinciding with the northern front of the gyration, serves still + further to promote the revolving movement which may thus result from + the partial coalescence of these great winds of Central America, and + the contiguous seas. + + "Thus, while a great storm is, in part, on the Pacific Ocean, its N. + E. wind may be felt in great force on that side of the continent, + through the great gorges or depressions near the bays of Papagayo or + Tehuantepec, as noticed by Humboldt, Captain Basil Hall, and others, + the elevations which there separate the two seas being but + inconsiderable; and, when the gyration is once perfected, the whole + mass will gradually assume the movement of the predominant current, + which is generally the higher one, and will move off with it, + integrally, as we see in the cases of the vortices, which are + successively found in particular portions of a stream, where subject + to disturbing influences." + +The analogy between this and the theory of Professor Dove, cited above, +and prior, in point of time, is obvious. They are substantially alike in +principle, with different locations. They differ also in this, Professor +Dove appears to think something more than over-sliding necessary, and +assigns the duty of crowding the upper current down in to the lower, to +make an _encounter_, to a lateral overflow from Africa. Mr. Redfield seems +to think there may be a tendency to deflection when they "over-slide" each +other. They are both closet hypotheses, the poetry of meteorology, with +something more than poetical license as to facts. + +In the first place, _no such concurring winds exist in the same locality +at the same time_. When the inter-tropical belt of rains is over Central +America and Southern Mexico, a S. W. monsoon blows in under it, but it +usurps the place of all other surface winds; and, when the belt is absent, +that portion of the eastern Pacific is most remarkably calm, or is covered +by the N. E. trades. Secondly, the _trade-winds every where pursue their +appointed course without "tendency to deflection" by the meeting, or +"over-sliding," or "breaking in," or "encounter,"_ of other winds. The +great laws of circulation do not admit of any such _confusion_. And, +lastly, _no storm ever came over the eastern United States from that +quarter_. The unchangeable laws of atmospheric circulation forbid it. +Recent observations also have shown that the storms on the west coast of +Central America, and the eastern Pacific, pursue a N. W. course, precisely +as in the West Indies, and every where over the surface-trades of the +northern hemisphere. Indeed _Mr. Redfield himself has recently +investigated several of them, and admits their course to be +north-westerly_. (See American Journal of Science, new series, vol. xviii. +p. 181.) + +But, suppose the co-existence of the winds and the course of the storms +admitted as claimed, let us seek for clearer views. What do these +gentlemen mean? Do they intend to have us believe the air has inherent +moving power, and that the "tendency" of which they speak is an attribute +of the winds, and that when they thus meet, and "come into each other," +"encounter," or "over-slide," and become acquainted, they wheel into a +waltz, and move off northward, "integrally," with unceasing circular +movement, even until they arrive at the Arctic circle? Or is it a mere +mechanical effect of meeting, "coming into each other," or "over-sliding?" +If the latter, why a tendency to rotation from right to left? The +trade-winds, at least, are _continuous, unbroken sheets_, and not +disconnected portions which meet and blow past each other, and there is no +warrant for placing them _side and side_, and attributing to them any +such mechanical effect, and as little respecting the other winds. Outside +of the fanciful hypothesis, there are no facts to show such a tendency one +way rather than the other; and, in accordance with the known facts +regarding stratification of the currents of air, no such "tendency" can +exist. + +But what _power_ impels the winds, which thus meet at these points? If +they be impelled, is it consistent with the action of this power that the +_winds_ it has _created_ and _controls_, should thus assume an _opposite +"tendency,"_ and whirl away to the north-eastward, regardless of the power +that originated and controls them? What must this "_tendency_" be, which +thus _occasionally_ not only diverts the winds from the _usually regular +course_ given them by their originating power, but increases their action, +from gentle, ordinary winds, to hurricanes? Nay, which gives them a new, +resistless gyratory and electric energy, increasing as the new, +independent, supposed cyclonic organization moves off, "_integrally_," +away from "the home of its many fathers," on a devastating journey towards +the north pole? + +And, further, if all this were true as to the West Indies and Central +America, what is to be said of the billions of other storms, originating +on a thousand other portions of the earth's surface, and how are they to +be accounted for, inasmuch as such other "meetings," "coming into each +other," and "over-sliding," and "tendency to deflection," is not assumed +to exist? + +These questions cannot be satisfactorily answered. The distinguished +theorists are mistaken. The stratus-cloud does not over-lie or cover the +storm. IT IS THE STORM. The winds beneath, whether surface or +superimposed, are but its incidents, due to its static induction and +attraction. Their _direction_ depends on the shape of the storm cloud, and +its course of progression, and the susceptibility of the surface +atmosphere in this direction or that, to its inductive and attractive +influence. Their _force_ to its depth, its contiguity to the earth, and +the intensity of its action; and the scud, are but patches of +condensation, occasioned by the same inductive action which affects and +attracts the surface current in which they form. + +Another objection to Mr. Redfield's theory of gyration is based upon the +fact that in order to constitute his _storm_, to get the _gyration_, he +has to include, at least, an equal amount, generally a great deal more, of +_fair weather_. The N. W. wind, the "posterior, or dry side of the gale," +as he calls it (in the foregoing extract), is a _fair weather wind_. It is +_necessary_, however, to complete the supposed _circle_, and it is +_pressed into the service_. The practical answer given to the question, +"_what are storms?_" is, they are cyclones, part storm, so called, and +_part fair weather_; that is, the stratus-cloud, the scud, the easterly +wind, and rain or snow of day before yesterday, were the _wet side_, or +front part of the storm, and the sunshine, clear sky, and N. W. wind of +yesterday, to-day, and, perhaps, to-morrow, are the posterior or dry side. +When a storm clears off from the N. W. it is not _over_, it is, perhaps, +_just begun_; and, inasmuch as it storms again, very soon after the wind +changes back from the N. W. to the southward, in winter, our weather then +is pretty much all _storms_. + +The statement of this claim seems so absurd that it may appear like +injustice to make it. But gyration can not be made out without it, and it +is evident in the extract quoted above; in the claim that the winter +northers of the Mexican Gulf are parts of passing storms; and clearly and +unequivocally advanced as a distinct proposition, as follows: + +"1. The body of the gale usually comprises an area of rain or foul +weather, together with another, and, perhaps equal, or greater, area of +fair or bright weather." (Am. Jour. of Science, vol. xlii. p. 114.) + +Now, in the first place, we must distinguish between a storm and fair +weather, before we can tell what the former is, and it is difficult to +assent to a theory which explains what a S. E. storm of _twelve hours'_ +continuance is, by including _two or three days of succeeding N. W. fair +weather wind_, as a part of it. There is no proportionate relation as to +_time_, nor any relation as to _qualities_, or the attending conditions of +the atmosphere, nor any conceivable _connection_, except the hypothetical +one of _gyration_, between the two winds. + +And, in the second place, it is true, and Mr. Redfield is well aware of +the fact, that winds often blow for many days from the N. E., S. W., or N. +W., without any preceding or succeeding winds to which they have any +discoverable relation. If, therefore, truth would justify Mr. Redfield in +including the fair weather wind, a difficulty would remain which his +theory does not cover or explain. + +No American, except Mr. Redfield, has been able to discover satisfactory +evidence of the gyration of storms, by actual careful observation, or a +careful unbiased collation of the observation of others. Professor Coffin +is reported to have read to the Scientific Association, at their Buffalo +meeting, a paper, confirmatory, in part, but I have not been able to see +it. The tracks of tornados have been searched as with candles. When they +have been narrow, from forty to eighty rods, their action has been +substantially similar, and, although, as we have herein before stated, +some irregularities have been found which were consistent with +gyration--for irregularities attend the violent action of all forces, and +particularly the motion of electricity through the atmosphere, as every +one who has seen the zig-zag course of a flash of lightning knows--yet the +evidence of two lateral inward currents, or lines of force, has +predominated over all others. In all cases, where the path is narrow, +those lateral currents are the actors; they constitute the tornado; their +_irregularities_ of action produce the exceptions; but the exceptions are +neither numerous nor uniform, and do not prove either the theory of Mr. +Espy or that of Mr. Redfield. The action is not that of moving air, +merely, but of a power exceeding in force that of powder, which nothing +but electricity or magnetism can exert. As the path widens, the wind +becomes more like the straight-line gust which follows beneath the +ordinary severe thunder-showers. His theory finds no substantial +confirmation or support in the path of the tornado. + +Several storms were investigated by Professor Espy, some of them the same +which Mr. Redfield had attempted to show were of a rotary character; one +or two by the Franklin Institute of Philadelphia; one by Professor Loomis, +already alluded to; and recently, two by Lieutenant Porter, from logs +returned to the National Observatory. None of these investigations confirm +the theory of Mr. Redfield. Indeed, Mr. Redfield himself has found it +necessary to resort to suppositions of _modifying causes_ to explain the +evident inconsistencies. It is assumed that the axis, or center, +oscillates, and describes a series of circles; and thus, one class of +difficulties is avoided. Again, it is assumed that simultaneous storms +converge and blend upon the same field, and another class of difficulties +are surmounted. And, again, inasmuch as it is notorious that violent gales +are rarely if ever felt with equal violence around the area of a circle, +but from one or two points only, it is assumed, that the storm winds +ascend, superimpose, and descend again, when they return to the place of +their first violent action, etc. The _simple truth_ requires no such +resort to _modifying hypothesis_. + +Still, another objection is, that the changes in the barometer, which +occur before, during, and after storms, do not sustain the claims of Mr. +Redfield or the requirements of his theory. + +The barometer sometimes rises before storms. It generally commences +falling about the time, or soon after the storm sets in, continues to fall +during its progress, and rises again, sooner or later, afterward. This is +the general rule. + +On this subject Mr. Redfield's claim is this: + + "EFFECT OF THE GALE'S ROTATION ON THE BAROMETER.--The extraordinary + fall of the mercury in the barometer, which takes place in gales or + tempests, has attracted attention since the earliest use of this + instrument by meteorologists. But I am not aware that the principal + cause of this depression had ever been pointed out, previously to my + first publication in this journal, in April, 1831, when I took the + occasion to notice this result as being obviously due to the + _centrifugal force_ of the revolving motion found in the body of the + storm. + + "Since that period, inquiries have been continued by meteorologists + in regard to the periodical and other fluctuations of the barometer, + and the relations of these fluctuations to temperature and aqueous + vapor. But these incidental causes of variation, in the atmospheric + pressure, prove to be of minor influence, and we are left to the + sufficient and only satisfactory solution of this marked phenomenon + which is found in the centrifugal force of rotation." + +The average pressure of the atmosphere, at the surface of the ocean, or in +the interior of the country, allowing for elevation, is about equal to the +weight of a column of quicksilver, thirty inches in height; hence the +barometer is said to stand at about thirty inches at the level of the sea. + +This is sufficiently accurate for the northern hemisphere, north of the N. +E. trades; but the average is somewhat lower in the trades and in the +southern hemisphere. Thus, the average of sixteen months, during which the +Grinnell expedition was absent, was 30.08/100. + +From a large number of logs examined by Lieutenant Maury, the mean +elevation in the N. E. trades of the Atlantic was 29.97/100; the S. E. +trades of the Atlantic, 29.93/100; off Cape Horn, 29.23/100; S. E. trades +of the Pacific, 30.05/100; N. E. trades of the Pacific, 29.96/100. The +height of the barometer off Cape Horn is not a fair index of the general +elevation of the southern hemisphere, inasmuch as it stands lower there +than at the coast of Patagonia and Chili, or at most, if not all, other +stations in that hemisphere. + +As the barometer is constantly oscillating up and down (irrespective of +its diurnal oscillation), it has no known fair weather standard. The point +of 30 inches is taken only as it is a mean. I have known it to commence +storming when the barometer was at 30.70, and not to fall before it +cleared off, below 30.30. And I have known it to be below 30 for several +days consecutively, with fair weather. In our climate there is no reliable +fair weather standard for the barometer. It falls below 30 without +storming; it rises far above, and storms without falling below. No +reliance can be placed upon its elevation, except by comparison; but of +that hereafter. + +The general rule, nevertheless, is, that it falls more or less during +storms, whatever its height, and rises sooner or later, more or less, +after they clear off. + +The difference between its highest and lowest points is called its range. +The greatest range observed, and recorded, is about 3 inches--from about +28 to 31--but this range is rare. The range, in the trade-wind region, is +comparatively small; in this country it is greater than in Europe; and, +generally, the range will be found greatest where the volume of +counter-trade, and magnetic intensity, and the corresponding amount of +precipitation, and extremes of heat and cold are greatest. One of the +greatest ranges during one storm, or two successive portions of a storm, +in this country, which I have seen recorded, occurred at Boston, in +February, 1842. It was as follows--counting the hours as 24, and from +midnight: + + Feb. 15..10h..30.36. + " 16..13h..28.47 fall of 1.89 in 27 hours. + " 17..19h..30.39 rise of 1.92 in 30 hours. + " 18.. 2h..30.39 stationary 5 hours. + " 19.. 2h..29.46 fall of 0.93 in 24 hours. + " 20.. 2h..30.43 rise of 0.97 in 24 hours. + Amount of oscillation, 5.71 in 4 days, 11 hours. + +These ranges were owing to the alternation of S. E. storms, and N. W. +winds. + +Taking the first range as a basis, and allowing the height of the +atmosphere to be 1,100 feet for the first inch, we have nearly 2,000 feet +displaced during one day, if we look for the displacement near the earth, +or some 30 or 35 miles, if we soar aloft in the upper regions to look for +the _lateral overflow_ of Professor Dove, and about the same quantity +restored the next. This brings us to the inquiry, how was it done? It is +perfectly idle to talk about _difference_ of _temperature_ or _tension_ of +_vapor_, the _ascent_ of warm air, or _descent_ of cold in a case like +this; or to say that they were occasioned by a lateral overflow of some +thirty miles of its upper portion, first this way and then that, in such a +brief space of time. The change is equal to nearly 1/15 of the weight of +the whole atmosphere, and the cause, whatever it was, existed within two +or three miles of the earth. Mr. Redfield's explanation I give in his own +words, at length: + + "One of the most important deductions which may be drawn from the + facts and explications which are now submitted, is an explanation of + the causes which produce the fall of the barometer on the approach of + a storm. This effect we ascribe to the centrifugal tendency or action + which pertains to all revolving or rotary movements, and which must + operate with great energy and effect upon so extensive a mass of + atmosphere as that which constitutes a storm. Let a cylindrical + vessel, of any considerable magnitude, be partially filled with + water, and let the rotative motion be communicated to the fluid, by + passing a rod repeatedly through its mass, in a circular course. In + conducting this experiment, we shall find that the surface of the + fluid immediately becomes depressed by the centrifugal action, except + on its exterior portions, where, owing merely to the resistance which + is opposed by the sides of the vessel, it will rise above its natural + level, the fluid exhibiting the character of a miniature vortex or + whirlpool. Let this experiment be carefully repeated, by passing the + propelling rod around the exterior of the fluid mass, in continued + contact with the sides of the vessel, thus producing the whole + rotative impulse, by an external force, analagous to that which we + suppose to influence the gyration of storms and hurricanes, and we + shall still find a corresponding result, beautifully modified, + however, by the quiescent properties of the fluid; for, instead of + the deep and rapid vortex before exhibited, we shall have a concave + depression of the surface, of great regularity: and, by the aid of a + few suspended particles, may discover the increased degree of + rotation, which becomes gradually imparted to the more central + portions of the revolving fluid. The last-mentioned result obviates + the objection, which, at the first view, might, perhaps, be + considered as opposed to our main conclusion, grounded on the + supposed equability of rotation, in both the interior and exterior + portions of the revolving body, like that which pertains to a wheel, + or other solid. It is most obvious, however, that all fluid masses + are, in their gyrations, subject to a different law, as is + exemplified in the foregoing experiment; and this difference, or + departure from the law of solids, is doubtless greater in aeriform + fluids than in those of a denser character. + + "The whole experiment serves to demonstrate that such an active + gyration as we have ascribed to storms, and have proved, as we deem, + to appertain to some, at least, of the more violent class; must + necessarily expand and spread out, _by its centrifugal action, the + stratum of atmosphere subject to its influence, and which must, + consequently, become flattened or depressed by this lateral movement, + particularly toward the vortex or center of the storm_; lessening + thereby the weight of the incumbent fluid, and producing a consequent + fall of the mercury in the barometrical tube. This effect must + increase, till the gravity of the circumjacent atmosphere, superadded + to that of the storm itself, shall, by its counteracting effect, have + produced an equilibrium in the two forces. Should there be no + overlaying current in the higher regions, moving in a direction + different from that which contains the storm, the rotative effect + may, perhaps, be extended into the region of perpetual congelation, + till the medium becomes too rare to receive its influence. But + whatever may be the limit of this gyration, its effect must be to + _depress_ the _cold stratum_ of the upper atmosphere, particularly + toward the more central portions of the storm; and, by thus bringing + it in contact with the humid stratum of the surface, to produce a + permanent and continuous stratum of clouds, together with a copious + supply of rain, or a deposition of congelated vapor, according to the + state of the temperature prevailing in the lower region." + +The italics in the foregoing extract are mine; and, in relation to it, I +observe: + +1st. There is no cylindrical vessel around storms, and _air will not thus +resist air_. Confessedly, such resistance is necessary. Let any one watch +his cigar smoke, and see how readily it moves on, with little momentum. +Let any one try the experiment of creating a whirl in the _open air_, or +in a room, or box of paper, or other material, which can be suddenly +removed, with air colored by smoke. I am exceedingly mistaken if he does +not find the presence of a "cylindrical vessel," absolutely essential to +prevent the instantaneous tangential escape of the air. + +2d. Turn back to page 3 and look at the fall of the barometer in the polar +regions (recorded in the extract from Dr. Kane), with _scarcely any +wind_, and _as little variation_ in its _direction_, and see how utterly +Mr. Redfield's theory fails to account for the phenomena. + +3d. If I understand Mr. Redfield correctly, he has abandoned the claim as +originally made, that the wind moves in circles, expanding, and _spreading +out_ by a "_lateral movement_," and now asserts that it blows spirally +inward, and elevates the air in the center. I quote: + + "VORTICAL INCLINATION OF THE STORM WIND.--By this is meant some + degree of involution from a true circular course. In the New England + storm above referred to, this convergence of the surface-winds + appeared equal to an average of about 6 deg. from a circle. In the + present case, such indication seems more or less apparent in the + arrows on the storm figures of the several charts, where the + concentrical circle afford us means for a just comparison of the + general course of wind which is approximately shown by the several + observations. + + "Perhaps we may estimate the average of the vorticose convergence, as + observed in the entire storm for three successive days, at from 5 deg. to + 10 deg.--out of the 90 deg. which would be requisite for a congeries of + _centripetal_ or center-blowing winds. This rough estimate of the + degree of involution is founded only on a bird's-eye view of the + plotted observations. But, however estimated, this involution seems + to afford a measure of the air and vapor which finds its way to a + _higher elevation_ by means of the vortical movement in the body of + the storm." + +If the elevation of the air at the borders of the storm, and depression in +the middle, resulted from the outward tendency and "lateral movement" of +the revolving air, and from the _centrifugal force_, as in the experiment +with the water in a cylindrical vessel, as stated in the first paragraph +quoted, an _involution_ of from 5 deg. to 10 deg. from the action of a +_centripetal force_, must carry the air _inward_, and the _barometer +should stand highest in the middle of the storm_. The change is fatal to +his theory. The two are diametrically opposite in character and effect. In +one, the superior strata would be brought down in the center by the +_lateral pressure outward_; in the other, they would be elevated by the +_involution_, which "affords a measure of the air and vapor which finds +its way to a higher elevation," etc. It is perfectly obvious Mr. Redfield +has refuted his own hypothesis. + +In doing this, he is met by the other difficulty alluded to, which he does +not attempt to explain. This gathering of the air inward, spirally, by a +centripetal force, if it took place, not only would not depress, but _must +elevate the barometer in the center, above that of the adjoining +atmosphere_. + +When he first attributed the depression of the barometer to a lateral +movement and centrifugal force, he supposed the superior strata descended +into the depression, and their frigidity occasioned the condensation, and +cloud, and rain. How he now proposes to account for the formation of cloud +and rain during storms, while the warm air of the inferior stratum finds +its way to a higher elevation in the center of the storm, he does not +inform us, and we must wait his time. + + "I have," he says, "long held the proper inquiry to be, _what are + storms_? and not, _how are storms produced_? as has been well + expressed by another. It is only when the former of these inquiries + has been solved that we can enter advantageously upon the latter." + +The former does not seem to be yet solved, or the solution of the latter +commenced. Mr. Redfield tells us (page 259, and onward), that there is an +extended stratum of stratus-cloud, which overlies the storm, and that it +does not differ greatly from one mile in height. We are not told how the +air, which finds its way to a higher elevation during several days +continuance of such a storm, _gets through the stratum_. If he is right it +_must_ do so, and it would not answer to _suppose_ a very small opening or +gentle current through it, to carry off all the air which works inward in +a hurricane, during several days continuance. But he does not seem to +recognize either the necessity or existence of any _vent_ at all; nor is +there any; and this fact is open to the observation of every school-boy in +the country; and it is equally open to his observation that _when and +where the barometer is most depressed, the stratus storm-cloud is nearest +the earth_. Colonel Reid has much to say about the "_storm's eye_," or +"treacherous center" of a storm. A careful analysis of the instances where +the "storm's eye" is noticed will show that the term is applied, in the +northern hemisphere, to that lighting up in the W. or N. W., which is the +commencement of the clearing-off process, and attended with a shift of +wind to the fair-weather quarter: _i. e._, to W. or N. W. Just such an +"eye" as is seen when the last of the storm cloud has passed so far to the +east as to admit the rays of the sun under the western or north-western +edge of it. The same kind of "storm's eye" is described in the southern +hemisphere, except that the wind shifts to S. W. instead of N. W., that +being the clearing-off wind there. No instance of a "_storm's eye_" in +the center of the extended stratum of stratus-cloud, which overlies the +storm, can be found recorded, to my knowledge; and it is obvious that +Colonel Reid adopts the view of Mr. Redfield, that the westerly and N. W. +_fair weather_ winds are a part of the storm. So long as these gentlemen +hold to that opinion they will never solve the question, "_what are +storms?_" or reach the other, "_how are storms produced?_" + +Notwithstanding, Mr. Redfield asserts, or adopts the assertion, that the +inquiry should be, "What are storms?" not "How are storms produced?" that +inquiry should be a _rational_ one, and should not violate all analogy, or +call for an explanation which science can not _rationally_ furnish. Mr. +Redfield does not seem to have formed any just conception of the +_immeasurable power_ of a hurricane, _five hundred miles in diameter_; or +of the nature of that _rod_ which the _Almighty must insert in it, to +whirl it with such violent and long-continued force_; nor any just +conception of the tendency of the whirling mass, in the absence of his +"cylindrical vessel," to fly off, tangentially, into the surrounding air; +or of the nature or power of the centripetal force necessary to hold the +gyratory mass in its current, and gather it in involute spirals toward a +center. Nor has any other man who has witnessed, or read of +mountain-tossed waves; of the largest ships blown down and engulfed; of +towns submerged, and vessels carried far inland, and left in cultivated +fields, by the subsidence of the sea; of sturdy forests and strongly-built +edifices prostrated; or listened to the howling of the tempest, and felt +his own house rock beneath him, been able to conceive of any known form of +calorific or mechanical, or other power, acting from a comparatively small +center, which could hold such an immense irresistable mass of whirling air +in a circle, and _gather it_ in toward the center in gradually contracting +spirals. I confess that, to my mind, it seems little less than a mockery +of our intelligence for Mr. Redfield, or Professor Dove, or any other man, +how distinguished soever he may be, to tell us that all this is the result +of a "tendency to left-wise rotation" of ordinary winds, "coming into each +other," or "over-sliding," or "meeting," or "encountering," on this +"front," or that, down in Central America, or in the West Indies, or the +monsoon region; or to talk of "lateral overflows" from mere gravity; of +the ascent of warm air, or the descent of cold strata; of the _resistance +of adjacent passive air_, or other mere _atmospheric resistances_ in +connection with such _awful manifestations of power_. Their explanations +of these phenomena are not rational, nor can they be believed by any +rational man, who will bestow upon them half an hour of _comprehensive, +unbiased reflection_. + +Waiving many minor points of great force, for this notice of Mr. +Redfield's theory is already too much extended for my limits, I am +constrained to take issue with him on the fact, and to assert, +unhesitatingly, that in a _majority of instances no such barometric curve +exists_. + +Doubtless the depression beneath the storm is found, and exterior lateral +elevations may also be had by _extending the line into the usual fair +weather elevation on each side_, as Mr. Redfield is obliged to do, to get +his supposed circle of winds at all. Doubtless, too, the seamen sailing +out of a storm, on either _side_, and approaching fair weather, will have +a rising barometer. But from _front to rear, on the line of progression_, +in tropical storms, the curve does not exist on shore, in this latitude, +oftener than in two, or possibly three, cases in ten; and then only upon a +single state of facts--that is, when there is an interposition of N. W. +wind; and this, at some seasons, rarely occurs. An elevation usually +occurs before the storm, on its front, if it present an extensive easterly +front, as one of these classes does, and a _depression is left_ after it +has passed off, unless a considerable body of N. W. wind interposes, as +heretofore stated. But when there is not such interposition of N. W. wind +(for W., W. N. W., or even N. W. by W. will not suffice), there is not an +immediate rise of the barometer corresponding in rapidity and extent with +the fall, and frequently none during the first twenty-four hours of +bright, fair weather. Let the reader, if he has access to a barometer, +note this fact, for it is obvious and conclusive. + +Finally, there are other atmospheric conditions to which the barometric +changes are obviously due: + +1st. The counter-trade is of a different _volume_, at different times, +over the same locality, and hence a difference in the normal elevations of +the barometer. + +2d. It is at a different _elevation_, at different times, over the same +locality. It was so found by the investigations of the Kew Observatory +Committee referred to; has been so found by other aeronauts, and may +readily be seen by a careful, practiced observer. + +It is highest, with a high barometer, in serene weather, when a storm is +not at hand; and can sometimes be plainly seen to ascend when a +considerable volume of N. W. wind is blowing in beneath, and elevating, +simultaneously, the trade and the barometer. + +Opportunities occur every year, when the northern edge of the dissolving +stratus-cloud is attenuated, and the storm is clearing off in the N. W., +with wind from that quarter, and a rising barometer, when its gradual +elevation may be observed to correspond with the _volume_ of that wind. + +3d. During storms, with a low barometer, the _trade_ and the _clouds run +low_. This, too, is clearly observable, especially when the stratus-cloud +passes off abruptly, very soon after the rain ceases. In such cases the +barometer will remain depressed for a considerable time, unless another +storm supervenes speedily, or the wind sets in from the N. W. + +4th. The _trade, in a stormy state, moves faster_ than when in a normal +condition. This is observable during the partial breaks which frequently +occur in storms, and at other times. It is also inferable from the more +rapid progress of the more intense center, and other intense portions of +storms, and the consequent greater depression of the barometer, under such +centers or intense portions. (See the storm of Professor Loomis.) It is +obvious, also, from the greater rapidity of progress attending the more +intense and violent storms which all investigations discloses. + +These simple facts explain all the phenomena: + +1st. The trade stratum is a continuous unbroken sheet, and its descent +must displace a portion of the surface atmosphere. A portion of it is +impelled forward, aiding in the precedent elevation of the barometer, and +a portion is attracted backward, into the space from which a like portion +had been previously attracted by the passing storm cloud, forming the +easterly wind. + +2d. The increased progress of the stormy portion of the counter-trade +occasions an accumulation in front of the storm, and an elevation of the +barometer, and tends also to increase the _depression_ under the spot from +which it moves. The latter is, to some extent, counteracted by the thin +sheets of surface wind which are drawn in under the stratus from the +sides. That which is drawn from the front in successive portions, fills +the space from which like portions had been drawn to the westward, and +left behind in a passive state by the passing storm. Thus, the surface +atmosphere of New England may pass under the entire width of a storm, as a +gale; moving now in puffs with great violence, as it passes beneath +irregular and intense portions of the cloud, and now moderately; and be +left, in a passive state, in Kentucky, occupying the space from which the +atmosphere had been previously drawn by the same storm, _in like manner_, +on to northern Texas. + +3d. The nearer the stratus-cloud to the earth, the greater the +displacement of surface atmosphere, the lower the barometer, and, +ordinarily, the more violent the wind. First, because the same intensity, +which, by attraction, brings the trade near the earth, acts with greater +force upon the surface atmosphere; and, secondly, the storm winds, which +are often most rapid beneath the clouds and above the earth, are likely to +be felt with more violence at its surface, where the stratus cloud runs +low, especially at sea. + +I desire to commend all these facts, in relation to the theory of Mr. +Redfield, to the careful attention and observation of those who, although +believers in the theory, are not wedded to it; and who have a sincere +desire to understand the phenomena which are continually, and thus far, +_mysteriously_, occurring within two or three miles of us, while our +knowledge of the distant worlds around us--the science of astronomy--seems +almost perfect. + +I will return to a further and a careful consideration of the nature of +the reciprocal action between the earth and the counter-trade, and the +facts bearing upon the question, in another chapter. It is obvious that +received theories can not aid us materially in the inquiry. + + + + +CHAPTER X. + + +We are yet ignorant of the true nature of magnetism. We trace its lines, +as in the diagrams, upon and around the magnet; but we can only do this +with soft iron, or other substance, in which magnetic action may be +induced. We know that these lines are currents, or lines of force, for +that force produces sensible effects, and we measure it by the movements +of the needle. We know that these lines may be _deflected_ by other +magnetic bodies, and concentrated upon them. We know that the earth, and +the smallest magnets, exhibit properties in common. The poles of the +magnet are some distance from its extreme ends--so are those of the earth. +The intensity increases, from the center, or near it, to the poles of the +magnet, as shown by its attraction; and the same increase of magnetic +intensity, from the magnetic equator to the magnetic poles, or near them, +is traced upon the earth. + +We know that there are two lines, or rather _areas_, of greater intensity +upon the globe. One extending from the American magnetic pole, +south-eastwardly, to a corresponding pole in the southern hemisphere; and +another, the Asiatic, extending from the Siberian pole to a corresponding +southern one, in like manner. We know that, from those lines or areas, +the intensity, east and west, on the same parallel of latitude, decreases +each way, to about midway between them. Thus, calling the intensity where +Humboldt found the magnetic equator over South America, in 7 deg. 1' south +latitude, 1, or unity--the least intensity known is, .706, found at the +magnetic equator, over the South Atlantic, and at its most southern +depression; and it increases to 1.4 in the West Indies, and to 2.0099 upon +one or more points of the North American continent, south of the magnetic +pole, and about the meridian of 92 deg.. That it is 1.805, at Warren, Ohio, in +latitude 41 deg. 16', and longitude 72 deg. 57', and decreases to 1.774 at New +Haven, Connecticut, in latitude 41 deg. 18'. That it is but 1.348 at Paris, +nearly one third less than on the same latitude in some portions of this +continent. That the line of equal intensity, or "_iso-dynamic_" line, of +1-8/10, is a closed curve of an oval shape, extending somewhat below 40 deg., +in the longitude of Cincinnati, and reaches off nearly to Bhering's +Straits, on the west; rising in a similar manner, though not so abruptly, +on the east; including the great northern lakes and a considerable part of +Hudson's Bay. While the iso-dynamic lines of 1-85/100, and 1-875/1000, are +smaller ovals, included within the former. Such, at least, is the present +belief from such investigations as have been made. (See an article by +Professor Loomis, American Journal of Science, new series, vol. iv. p. +192.) + +Our subject demands a still closer examination of the elements of +magnetism and its associated electricities, and their influence upon +climate and the atmosphere with a view to the solution of the questions in +hand, and we will pursue the inquiry in the present chapter. + +Waiving, for the present, any further notice of the fact that the +counter-trades are concentrated over, and contiguous to, this area of +intensity, for the purpose of examining the magnetic phenomena +independently, and intending to return to a consideration of their +connection with it, we observe:--That it is now well settled that the +iso-geothermal lines, or lines of equal terrestrial heat, are coincident, +or nearly so, with the lines of equal magnetic intensity. The points where +the magnetic intensity is at a minimum, on the magnetic meridian, are the +warmest points of that meridian, and those where it is most intense, the +coldest. + +The magnetic elements of a place may be computed from its thermal ones. +The laws producing or governing the distribution of one, have an intimate +physical relation with those producing or governing the other. Professor +Norton ably sums up a discussion of the subject (in the American Journal +of Science for September, 1847), omitting the theoretic propositions, as +follows: + + "1. All the magnetic elements of any place on the earth may be + deduced from the thermal elements of the same; and all the great + features of the distribution of the earth's magnetism may be + theoretically derived from certain prominent features in the + distribution of its heat. + + "2. Of the magnetic elements, the horizontal intensity is nearly + proportional to the mean temperature, as measured by Fahrenheit's + thermometer; the vertical intensity is nearly proportional to the + difference between the mean temperatures, at two points situated at + equal distances north and south of the place, in a direction + perpendicular to the iso-geothermal line; and, in general, the + direction of the needle is nearly at right angles to the + iso-geothermal line, while the precise course of the inflected line + to which it is perpendicular may be deduced from Brewster's formula + for the temperature, by differentiating and putting the differential + equal to zero. + + "3. As a consequence, the laws of the terrestrial distribution of the + physical principles of magnetism and heat must be the same, or nearly + the same; and these principles themselves must have, toward one + another, the most intimate physical relations." + +The magnetic elements, of which Professor Norton speaks, are the +declination, dip, and horizontal and vertical forces or intensities. + +I have said, that toward the areas of greatest magnetic intensity, the +needle every where declines. So as intensity increases, from the magnetic +equator toward the poles, the needle, when so suspended as to permit of +the motion, _dips_, inclines downward, and the dip is greatest, on the +same parallel, where intensity is greatest. To my mind, the magnetic +elements are very intelligible. They are all attributable to attraction, +and attraction is greatest where intensity is greatest. There is nothing +in the earth or atmosphere to make the needle point northerly rather than +in any other direction, except magnetic intensity. Thus, the greater +intensity of magnetism near the northern and southern points of the globe, +attracts the corresponding ends of the needle in those directions. And, as +magnetism increases in quantity or intensity, and the poles are +approached, the attraction increases, and the needle dips more and more, +till the focus of intensity and attraction is reached, and then it becomes +perpendicular. So magnetism is unequally diffused, meridionally, in or +over the earth, and there are two equidistant areas where its quantity or +intensity is greatest. These exert a lateral attraction upon the needle; +it yields to this attraction, and hence its declination. If it is carried +on to one area of intensity, and to the center of it, it will point to the +northern focus of intensity or magnetic pole; and, if carried a trifle +further west, it will yield to an eastern attraction, and point directly +north. If carried still further west, its declination _east_ will +increase. Thus its normal direction is to the pole, on the central focus +of intensity, and when it points directly north it is west of the central +line of intensity. And thus, it seems to me, all the magnetic elements may +be resolved into the one element of attraction by excess of intensity or +activity. + +This impression is strengthened by the fact that the needle moves to the +east in the morning, when the solar rays increase magnetic activity in +that direction, and west again, as their influence increases there. + +Now, these elements--the declination and horizontal and vertical +forces--all these periodical, regular, and irregular variations of +magnetic activity, are intimately connected with the variations of +atmospheric condition: + +First, They show an increase of activity during certain hours of the day, +corresponding to, and obviously connected with, the diurnal atmospheric +changes. + +Second, They show an increase of activity during the northern transit of +the atmospheric machinery--an _annual_ variation. + +Third, They show an increase in that activity during the latter portion of +each decennial period, conforming to the occurrence of solar spots. + +And, fourth, _Irregular variations_ of activity, corresponding with the +_irregular changes_ of atmospheric condition. + +We will examine these results, and in doing so, take those of the element +of declination--one answering for all. + +The magnetic needle moves to the west in summer, from about 8 A.M. till +about 2 P.M., and the extent of its progress, during that period, +constitutes the magnitude of its daily variation. It is found that this +variation differs in different months, and that it is normally greatest in +the summer months, and least in the winter, in the ratio of about two to +one. It is further found, that in different years the maximum activity +occurs in different months, and that the years differ also, and there is a +distinctly marked decennial period, corresponding most remarkably with the +decennial maxima of recurring solar spots, as observed by Schwabe. Dr. +Lamont, of Munich, gives us the following table of magnitude of +declination there, for the ten years preceding 1851, which clearly +exhibits this fact, and also the greater intensity during the northern +transit of the atmospheric machinery. He says: + + "The magnitude of the variations of declination have a period of ten + years. For five years there is a uniform increase, and during the + following five years a uniform decrease in the variations. With us + the magnetic declination is a minimum at about eight o'clock in the + morning, and is greatest at two o'clock in the afternoon. Subtracting + the declination at eight o'clock from that at two o'clock, we obtain + _the magnitude of the diurnal motion_. From the hourly observations, + conducted in this observatory since the month of August, 1840, we + ascertain the following to be the magnitude of the diurnal motion for + each month separately." + + +-------------------------------------------------------------------+ + | | Jan. | Feb. | March.| April.| May. | June. | July. | Aug. | + +-------------------------------------------------------------------| + | 1841 | 3.72 | 5.13 | 8.43 | 11.49 | 11.47 | 11.49 | 10.07 | 9.86| + | 1842 | 3.65 | 4.74 | 8.34 | 10.33 | 9.31 | 9.78 | 8.38 | 9.03| + | 1843 | 3.82 | 4.08 | 6.87 | 9.71 | 9.24 | 10.14 | 9.57 | 10.08| + | 1844 | 2.81 | 3.43 | 6.95 | 9.53 | 8.42 | 8.88 | 8.38 | 9.28| + | 1845 | 2.20 | 4.69 | 8.26 | 11.93 | 10.88 | 10.73 | 9.44 | 10.42| + | 1846 | 3.30 | 6.94 | 9.53 | 12.27 | 12.58 | 11.21 | 11.37 | 11.49| + | 1847 | 3.30 | 6.35 | 9.85 | 12.43 | 11.81 | 11.76 | 10.94 | 12.87| + | 1848 | 6.52 | 9.01 | 11.96 | 14.56 | 14.22 | 13.80 | 14.67 | 15.40| + | 1849 | 7.27 | 8.42 | 14.08 | 16.86 | 13.67 | 13.86 | 12.57 | 11.54| + | 1850 | 5.98 | 8.84 | 12.15 | 14.32 | 14.05 | 13.39 | 12.53 | 12.68| + +-------------------------------------------------------------------+ + +----------------------------------------------------+ + | Sept. | Oct. | Nov. | Dec. | Autmn | Spring| Year.| + | | | | |& Wint.| & Sum.| | + |----------------------------------------------------| + | 8.78 | 6.82 | 3.71 | 2.89 | 5.12 | 10.53 | 7.82| + | 7.72 | 7.05 | 3.86 | 2.81 | 5.07 | 9.09 | 7.03| + | 8.81 | 6.82 | 3.82 | 2.79 | 4.70 | 9.59 | 7.15| + | 8.23 | 6.54 | 3.94 | 2.98 | 4.44 | 8.79 | 6.61| + | 8.82 | 7.34 | 4.49 | 8.34 | 5.89 | 10.87 | 8.13| + | 10.39 | 7.82 | 5.66 | 3.22 | 6.08 | 11.25 | 8.81| + | 12.06 | 11.53 | 7.06 | 4.70 | 7.63 | 11.98 | 9.55| + | 14.00 | 10.30 | 5.78 | 3.53 | 7.85 | 14.44 | 11.05| + | 10.79 | 9.12 | 5.41 | 4.09 | 8.06 | 13.21 | 10.64| + | 12.64 | 9.04 | 6.20 | 3.45 | 7.61 | 13.27 | 10.44| + +----------------------------------------------------+ + +The Philadelphia and Toronto observations disclose the same state of +facts. + +Dr. Lamont, also, in his article, gives us the following table of the +magnitude of the variations derived from observations at Gottingen: + + +--------------------+ + | Year.|Mean of Year.| + |--------------------| + | 1835 | 9.57 | + | 1836 | 12.34 | + | 1837 | 12.27 | + | 1838 | 12.79 | + | 1839 | 11.03 | + | 1840 | 9.91 | + | 1841 | 8.70 | + +--------------------+ + +A comparison of these tables, and particularly the latter, with Schwabe's +table of spots, is interesting. There is obviously a greater mean +variation when the spots are most numerous. Comparing the two with the +tables of Hildreth, in relation to the temperature, from 1830 to 1840, +there is, to say the least, a most remarkable coincidence. And there are +others equally remarkable. + +There are also irregularities of action disclosed by all, in different +months of the different years, and of the same year, which are obviously +connected with the difference of the seasons; and there are constantly +occurring irregularities and disturbances which correspond with the, as +constantly occurring, irregular atmospheric phenomena. A wide field is +here opened for investigation and research. I have not time or opportunity +to pursue it. Enough appears, so far as I have examined, to confirm the +belief that magnetism is actively concerned in the production of the +varied changes, as well as the normal conditions of the weather. + +In what manner does it act? An answer to this requires an extension of the +inquiry. The lines of magnetic force are every instant passing upward from +the earth, _around_ and _through_ us. Their connection with heat is +unquestionable. They are intimately associated, also, with another equally +obvious and intensely active agent--electricity. We speak of this as an +independent, imponderable, elementary body, but how little we yet know of +it. It is every where, in every thing, easily excited into action, and +then traceable to a certain, but limited extent. It is set in motion, and +becomes obvious to us, by the chemical action of the acids and metals of +a galvanic apparatus. We separate it from the atmosphere by friction and +excitation, upon non-conductors, as in the electric machine; by the +cleavage of crystals and other exciting operations. We obtain it from +magnets, by the magneto-electric machine, and from the lines of magnetic +force which are ever passing into the atmosphere from the earth, by +intersecting them with a movable iron wire, properly insulated. _From the +current of magnetism which has passed through us from the earth, +electricity may thus be separated and collected over our heads._ We set it +in motion, and obtain it _by heating_ different metals in connection, or +the same metal unequally; and from certain animals--like the torpedo and +the gymnotus--whose organization is such as to enable them to evolve it. +In all these cases, and they constitute an epitome of the principal +methods by which we obtain it in a distinct form, it is made to flow in +currents. When thus obtained, and imprisoned in non-conductors, it may be +discharged, and with somewhat different effect, as it is discharged in a +mass, disruptively, as it is called, as from the clouds in lightning, or +permitted to flow convectively, in currents, along the wires of a galvanic +apparatus, or in heated air, as from the earth to a cloud in the tornado. + +It is, moreover, capable of division into positive and negative, and when +concentrated or disturbed in one body, it tends to create a similar +disturbance or division in a contiguous mass. To this action of +electricity, the term static induction is applied. Thus, a positively +electrified body _induces_ a division of the electricity in a contiguous +body, if both are insulated or surrounded by a non-conducting medium; the +negative electricity of the contiguous body being attracted by, and +tending to pass to, the positive of the adjoining body, and the positive +being repelled to the opposite side. That, in its turn, if sufficiently +powerful, tends to disturb the electricity of its neighbor, and attract +away its negative electricity; or, if the body which contains it is free +to move, to attract that. Thus, by the conflicting action of a positive +atmosphere, and a negative earth, and perhaps counter-trade, influenced by +magnetism and the solar rays, the currents and winds of the atmosphere are +produced, the atmosphere moving with exceeding ease and rapidity. +Electricity, excited into currents, or obtained and discharged in either +of the methods enumerated, is identical in character, and produces certain +well-known effects: + +1st. Physiological.--Shocking and convulsing the animal system; producing +a peculiar sensation on the tongue, and a flash before the eyes, and in +sufficient quantity destroying life. + +2d. Magnetic.--_Deflecting the needle_, and, by a suitable arrangement of +wire into helices, _conferring magnetic power_, or constituting magnets. + +3d. Luminous.--Producing light--by a spark, as it does in natural +phenomena--by the glow, the brush discharge, the ball of flame, the flash, +or the chain of lightning, and probably the aurora. + +4th. Evolving heat.--Melting metallic substances by concentration, with a +great intensity of heat--as the wire of the galvanic apparatus, and as is +sometimes seen in the effects of lightning in fusing metals on persons +stricken; and setting combustibles on fire. + +5th. Attraction and repulsion.--Attraction, when the currents flow +parallel with each other, or are of opposite natures, and repelling when +of like character. + +6th. Induction.--Inducing attendant circular or other secondary currents, +such as may be seen in the atmosphere during its most violent displays of +active energy. + +7th. Capable of being dissipated by heated air, or carried off by +moisture, although isolated by dry air, of ordinary temperature, which is +a bad conductor. + +Now, although magnetism can not be collected, imprisoned, or discharged, +like electricity, or collected at all, but by its adherence to some +substance capable of magnetization, it is obvious there is an intimate +association, at least, between it and electricity. _They are never found +alone._ All _electricity_ will _magnetize_. All _magnetism_ will evolve +electricity. All _currents_ of _electricity_ have _encircling currents_ of +_magnetism_, and all deflect the magnetic needle. All magnetic currents +give out to intersecting wires, _currents of electricity_, and all magnets +_induce_ them. + +Electricity, therefore, whether identical in substance with magnetism, but +differing in form, or whether merely associated with it, as is variously +believed, should be present with magnetism in greater quantity or +intensity where magnetism is most intense, and active, and whenever +present, should be active and influential. And so we find, from +observation, the fact to be. No inconsiderable effort has been made by the +advocates of the caloric and mechanical theories, to ignore the agency of +electricity and of magnetism, in the production of the varied +meteorological phenomena. But it will not do. The phenomena, grouped and +analyzed, disclose a potential-controlling, magneto-electric agency, and +meteorology will advance rapidly to perfection, as a simple, intelligible, +and practical science, _as soon as that agency is admitted_. + +Electricity is always perceptibly present in storms and showers within the +tropics. Most of the rain, from the tropical belt, falls from "thunder +showers." So hurricanes and typhoons, and all tropical storms, are +confessedly, and in proportion to their intensity, "_highly electric_." +This excess of quantity or activity of electricity, exists in connection +with the movable atmospheric machinery. When it moves up north in summer, +and arrives at its highest point of northern transit, _storms_ are very +_uncommon_, and the tropical forms of cloud and showers, with thunder and +lightning, prevail. This is most obvious, if not most influential, where +the magnetic intensity is greatest. Violent showers, and gusts, and +tornadoes, are more frequent in this country than in Europe; and over the +area of greatest intensity, as in Ohio, than at a distance on the extreme +eastern or western coast. And the same is true over the intense magnetic +area of Asia. + +Electricity, too, like magnetism, has its diurnal, and doubtless its +annual and decennial variations, and also its irregular ones, and they are +most obviously and intimately connected. Magnetism and electricity +together, constitute the aurora. Its culmination is in the magnetic +meridian--it affects the telegraph wires--is connected with the irregular +disturbances which affect the magnetic needle, and does not exist in the +limits of the trades, although occasionally seen from thence, when it +passes south, and near them. + +The aurora sometimes extends south in waves, as do the magneto-electric, +atmospheric, periodical changes of cold and heat, and storm, and sunshine. +_The aurora is connected with the formation of cloud_, and with a smoky +atmosphere, similar to that with which we are familiar in summer and +autumn. Thus Humboldt (Cosmos, vol. i. pp. 191, 192). + +"This connection of the polar light with the most delicate cirrus clouds, +deserves special attention, because it shows that the electro-magnetic +evolution of light is a part of a meteorological process. Terrestrial +magnetism here manifests its influence on the atmosphere, and on the +condensation of aqueous vapor. The fleecy clouds seen in Iceland, by +Thienemann, and which he considered to be the northern light, have been +seen in recent times by Franklin and Richardson, near the American north +pole, and by Admiral Wrangel on the Siberian coast of the Polar Sea. All +remarked 'that the aurora flashed forth in the most vivid beams when +masses of cirrus-strata were hovering in the upper regions of the air, and +when these were so thin that their presence could only be recognized by +the formation of a halo round the moon.' These clouds sometimes range +themselves, even by day, in a similar manner to the beams of the aurora, +and then disturb the course of the magnetic needle in the same manner as +the latter. On the morning after every distinct nocturnal aurora, the same +superimposed strata of clouds have still been observed that had previously +been luminous. The apparently converging polar zones (streaks of clouds in +the direction of the magnetic meridian), which constantly occupied my +attention during my journeys on the elevated plateaux of Mexico, and in +northern Asia, belong, probably, to the same group of diurnal phenomena." + +Mr. William Stevenson gives us (in the London, Edinburgh, and Dublin +Philosophical Magazine for July, 1853) an interesting article on the +connection between aurora and clouds. His observations on this most +important branch of the subject trace a connection between the aurora and +the formation of cloud, and open up, as he says, "a most interesting field +for observation which promises to lead to very important results." Such +observations point with great significance, to the primary influence of +the magneto-electricity of the earth. + +To the difference in the magnetic intensity of the eastern portion of this +continent, compared with Europe and our western coast, very much of the +difference of climate, so far as temperature is involved, may be +attributed. We have seen in what manner the iso-thermal lines surround +these areas of intensity. So the most excessive climate--that is, the +climate where the greatest extremes alternate, other things being equal, +is upon or near the line or area of greatest magnetic intensity. I say +other things being equal, because large bodies of water modify climates by +equalizing the seasons--making the summers cooler and the winters warmer +than the mean of the parallel. + +Thus, our great interior lakes modify the climate in relation to +temperature in their vicinity. Their summers are cooler and their winters +warmer; but westward of them the same line of equal summer temperature, or +iso-thermal line, rises with considerable abruptness, and the winter, or +iso-cheimal line of equal temperature, falls in a similar manner. Thus, +the range of the thermometer, from the highest elevation to the lowest +depression, for the year, is very great, while in the tropics the range is +comparatively small. From observations made at the military posts of the +United States, Dr. Forrey deduced summer and winter lines of equal +temperature, starting from the vicinity of Boston and running west, which +showed most remarkably the rise of the summer lines as intensity +increased, and the fall of the winter lines in like manner. + +The influence of the lakes was also most obvious. The elevation of the +earth increases, going west, to about 700 feet at the surface of the +lakes, and to nearly 4,000 feet at the eastern base of the Rocky +Mountains; and, although temperature does not decrease to as great a +degree when the elevation above the level of the sea is _gradual_, yet +some allowance should doubtless be made for that elevation on this line. +When that allowance is made, the ascent of the summer line, to the north, +over the area of greatest intensity, is strikingly apparent. + +Dr. Forrey also instituted a comparison between Fort Snelling, where the +climate is as excessive, and the range of the thermometer as great, as in +any portion of the continent in the same latitude, with Key West, and I +copy his diagram. It is very instructive, showing the gradual mean rise of +the temperature, from January to December, inclusive, while the cross +lines show the _extremes of each month_. + +Perhaps the most interesting part of it, is the illustration of the +monthly extremes, and the contrast between them, in the excessive climate +of Fort Snelling, and the tropical one of Key West. Each is a type of the +climate in which it is situated. The annual range and monthly extremes are +small in tropical countries, and large in extra-tropical ones. The extreme +range, or greatest elevation of heat, contrary to what is generally +supposed, is greater at Fort Snelling than at Key West. But the climate of +the latter is modified by the adjoining ocean. + +I copy, also, a table (p. 304), showing the range of the thermometer for +the year, and the maxima and minima, during each month, at several other +places in this country, and at London and Rome, for the purpose of showing +the extent of the ranges compared with those places; and also, that these +great changes in each month occur very uniformly all over the country, +and may always be expected, and with considerable regularity. They are +incident to our climate. I wish I could engrave the foregoing diagram, and +the following table, upon the mind of every man, woman, and child in the +country; and under it, in ever-visible letters, these words of precaution: +CONFORM TO THE PECULIARITIES OF YOUR CLIMATE, AND CLOTHE YOURSELVES, AT +ALL TIMES, IN ACCORDANCE WITH THE ALTERNATIONS OF THE WEATHER. If heeded, +they would save thousands, every year, from premature death. + + +[Illustration: Fig. 18.] + + +The effect of this difference of magnetic intensity upon the climate of +Europe is marked. There, the excessive summer heat, which our greater +magnetic intensity and larger volume of counter trade give us, is unknown. +Hence, while we can grow Indian corn (which requires the excessive summer +heat) over all the Eastern States, up to 45 deg., and in some localities east +of the lakes to 47 deg. 30', and to 50 deg. west of them, to the base of the Rocky +Mountains, and notwithstanding the increase of elevation, they can not +grow it except over a limited area, and with limited success. Nor can +they, or the inhabitants of any other country except China, grow +profitably the kind of cotton which is so successfully grown in the +Southern States of the Union. Nor can China do so to a considerable +extent, because of the mountainous character of the surface. To a level +and remarkably watered country, greater magnetic and electric intensity, +and a greater volume of counter-trade, we are, and ever shall remain, +indebted, for an almost exclusive monopoly in the growth of two of the +most important staple productions of the earth. On the other hand, +although the same magnetic intensity, and its winter excess of positive +electricity and cold, make our winters extreme, there are but few of the +productions of temperate latitudes which we can not grow successfully, and +they are comparatively unimportant. + + A Fort Vancouver, Oregon Territory + B Fort Brady, outlet of Lake Sup. + C Hancock Barracks, Houlton, Me. + D Fort Armstrong, Rock Island, Ill. + E West Point, New York + F Washington, D. C. + G Jefferson Barracks, near St. Louis + H Fort King, interior of East Florid. + I Environs of London + K Rome, Italy + + A B C D E F H I J K + + Lat. 45 deg. 46 deg. 46 deg. 41 deg. 41 deg. 38 deg. 38 deg. 29 deg. 51 deg. 41 deg. + 37' 39' 10' 28' 22' 53' 28' 12' 31' 54' + Annual + Range. 78 110 118 106 91 84 89 78 67 62 + + Jan. Min. 17 -21 -24 -10 -1 14 10 33 16 29 + Max. 58 40 41 48 53 57 60 83 49 58 + Feb. Min. 32 -22 -11 -6 2 16 11 43 19 33 + Max. 55 44 42 56 56 62 70 84 54 60 + Mar. Min. 32 -7 -1 13 16 28 31 39 24 37 + Max. 60 51 54 70 72 70 76 87 60 65 + Apr. Min. 32 18 24 33 40 36 38 54 26 44 + Max. 70 62 74 78 62 73 83 93 69 74 + May. Min. 32 32 81 44 47 50 45 64 33 52 + Max. 75 79 83 84 72 85 88 97 78 80 + June. Min. 45 41 38 57 57 59 59 73 39 60 + Max. 95 86 90 89 79 92 95 105 80 88 + July. Min. 40 39 45 62 64 64 50 73 41 64 + Max. 95 84 90 95 86 94 96 102 83 91 + Aug. Min. 44 49 46 60 62 63 66 72 42 62 + Max. 95 84 85 91 87 93 96 104 79 91 + Sept. Min. 43 40 33 51 56 51 51 70 34 55 + Max. 88 75 78 87 83 88 88 99 75 85 + Oct. Min. 50 27 24 82 42 33 38 41 30 46 + Max. 66 70 72 73 69 77 80 91 68 77 + Nov. Min. 32 15 4 26 36 28 27 30 22 39 + Max. 58 58 60 64 63 66 69 82 56 67 + Dec. Min. 32 -7 -4 15 20 17 14 36 20 31 + Max. 55 42 53 62 56 61 64 79 53 60 + +This excess of magnetic intensity and electricity not only gives a +peculiar character to our vegetation, but also to our race, our animals, +and every thing. He who supposes that the restless activity and energy of +the people of the United States is the result of habit, or education, or +any fortuitous circumstances alone, is mistaken. Let him watch the +contrast in his own feelings during those occasional languid, damp, and +sultry, although not thermometrically, hot days--which so much resemble +the summer weather of England--with those days of bright, bracing, N. W. +and S. W. air, so much more frequent here, and he will appreciate the +difference. That term "bracing," so much in use, will express the effect +of this peculiar weather. It "girds up the loins," both of body and mind. +Men and animals can work with more ease, even in our peculiar extremes of +heat, than they can in England, and fatten with less. + +A similar difference in degree is found between our climate and that of +the Pacific portion of our country. Something is due to the difference in +the volume and moisture of the counter-trades, and something to the +contiguity of the Pacific Ocean; but to the difference in +magneto-electric intensity, the contrast is mainly due. Corn and cotton +will be grown, to some extent, in the valleys west of the meridian of +105 deg., but never as successfully as east of it. + +The aurora is periodical, like all the other atmospheric phenomena, but +its periodicity is not accurately ascertained. It is believed to have +occurred much oftener during the second quarter of this century, than +during the first. It is known, however, to occur most frequently in the +spring and fall; and during those periods when the active and rapid +transit of the atmospheric machinery produces the greatest degree of +magnetic disturbance. This identifies it with terrestrial magnetism. +Dalton gives us the following table of observations, arranged according to +the months when they were seen. + + Jan. Feb. Mar. Apr. May. June. July. Aug. Sept. Oct. Nov. Dec. + + (1) 18 18 26 32 21 5 2 21 23 36 38 9 + (2) 21 18 23 13 3 2 1 3 35 22 22 21 + (3) 21 27 22 12 1 5 7 9 34 50 26 15 + (4) 5 6 4 8 10 7 6 14 14 17 5 6 + +(1) contains those observed by him at Kendall; (2) are taken from another +list; (3) is MARIAN'S list of those observed before 1732; and (4), those +seen in the State of New York in 1828 and 1830. + +Mr. Stevenson's table of those observed by him at Dunse, from 1838 to +1847, inclusive, is as follows: + + Jan. Feb. Mar. Apr. May. June. July. Aug. Sept. Oct. Nov. Dec. + 32 20 18 18 3 0 2 14 43 34 30 23 + +Observations in this country correspond substantially with the foregoing. +They are, however, seen here in the summer months more frequently than in +Europe. See an article by Mr. Herrick (American Journal of Science, vol. +33. p. 297). In this, also, they conform to our greater magnetic intensity +and more excessive climate. + +The auroras appear to follow the polar belts of condensation and +precipitation. Dalton considers them indications of fair weather. They are +often most brilliant just after a storm has passed, but their continuance +is no indication that another will not follow within the usual period. + +The condensation with which the aurora is connected, is not, in my +judgment, often in the counter-trade, or below it, but above, where feeble +condensation has been seen by aeronauts when invisible at the surface of +the earth. Neither the height of this condensation, not that of the +aurora, have been satisfactorily ascertained. The aurora of April 7th, +1847, was a favorable one for observation. It was carefully and +attentively watched by Professor Olmsted, Mr. Herrick, Dr. Ellsworth, and +others, and they are intelligent and skillful observers.[9] But the nature +of the aurora forbids reliance on parallax, or measurements founded on the +time when, any portion of the bow or arch rises in range of a particular +star. The bow or arch moves southwardly, but the same rays or currents do +not. The wave of magnetic _activity_ moves south, and each successive +current, as it is reached by the _impulse_, becomes luminous. Hence the +observers, when distant, do not see, at the same time, or at different +times, the same rays. The phenomenon is unquestionably magneto-electric. +Electricity becomes luminous in a vacuum, and De la Rive, by combining the +electric currents with those of magnetism, produced all the peculiarities +of the aurora. The magnetic currents, passing from the earth, have +associated electric ones in connection, and these, in the upper attenuated +atmosphere, become luminous. Whether, as De La Rive supposes, by combining +with the positive electricity existing there, or because the associated +electric currents are _then_ in excess, not being intercepted by +atmospheric vapor and returned to the earth in rain, we can not know, nor +is it very important we should. + +Having thus taken a general view of the nature of magnetism and its +associated electricities, and their connection with the general and +obvious peculiarities of climate, let us approach more nearly the varied +atmospheric phenomena, resulting from variations of pressure, temperature, +condensation, and wind, and give them a closer consideration. They all +have regularity and periodicity--they all occur in degree, and in +connection with magnetism and electricity, during the twenty-four hours of +every serene and normal summer's day. Grouped together, in comparison with +the changes in the activity and force of the magnetic elements, their +connection is clearly discernible. + +The day may be said, with truth, to commence, in some portion of the +summer, at 4 A.M. The atmospheric does at all seasons. At that hour the +barometer is at its morning minimum. It has, as we have said, a +perceptible diurnal variation of two maxima and two minima. Its periods of +depression are at 4 A.M., and 4 P.M., and of elevation at 10 A.M., and 10 +P.M. The difference between the elevation and depression is considerable +within the tropics, where Humboldt tells us the hour of the day can be +known by the height of the barometer, and it decreases toward the poles. +At 4 A.M. it is then at one of its minima, and rises till 10 o'clock. + +At, or about the same period, and sometimes when the barometer is falling, +and previous thereto, there is a tendency to fog in localities subject to +that condensation. This tendency is sometimes observed at the other +barometric minimum, late in the afternoon or early in the evening, but +less frequently. The tendency to fog condensation is greatest in this +country about the morning minimum. It seems to be owing to the influence +of the earth; it is confined to the surface atmosphere, and is apparently +produced by the inductive agency of the negative electricity of the earth. +It disappears, whether it be high or low fog, about the time when the +barometer attains its morning maximum, or about 10 A.M. + +At about that period, when there has been fog, or earlier, when there has +not, and sometimes as early as 8 A.M., there is a tendency to trade +condensation--cirrus in mid-winter, and a cumulus in mid-summer, and, +during the intermediate time, a tendency to cirro-stratus, partaking more +or less of the character of one or the other, according to the season. + +Temperature, in summer, commences its diurnal elevation about 4 A.M., +also, and rises till about 2 P.M. From that time it falls with very little +variation till 4 o'clock the next morning. It has but one maximum and one +minimum in the twenty-four hours. + +As the morning barometric maximum approaches, and the heat increases the +magnetic activity, condensation in the trade appears, or induced +condensation in the upper portion of the surface atmosphere, that portion +near the earth is affected and attracted--and the "wind rises," according +to the locality, the season, and the activity of the condensation. The +tendency to blow increases with the tendency to trade and cumulus +condensation, and continues till toward night, when it gradually dies +away, unless there be a storm approaching. As the heat increases, and +stimulates magnetism into activity, the magnetic needle commences moving +to the west, its regular diurnal variation, and continues to do so until +about 2 P.M., when it commences returning to the east, and so continues to +return until 10 P.M., when it moves west again until 2 A.M., and from +thence to the east, till 8 A.M. + +Similar variations also take place in the horizontal force, as evinced by +the action of the magnetometer needle, and in the vertical force, as shown +by the oscillations. So that it is evident that there are two maxima, and +two minima of magnetic activity every day, shown by all the methods by +which we measure magnetic action and force--more than double at the acme +of northern summer transit over that of winter, and proceeding _pari +passu_, with the other daily phenomena--evincing the same irregular action +which the other phenomena evince. Still another phenomenon, which has a +daily change, is electric tension, or the increase or decrease in the +tension of the positive or true atmospheric electricity. + + +[Illustration: Fig. 19.] + + +The following table shows the mean two hourly tensions for three years, at +Kew, viz.: + + Hours 12 P.M. 2 A.M. 4 A.M. 6 A.M. 8 A.M. 10 A.M. + Number of observations 655 784 804 566 1,047 1,013 + Tension 22.6 20.1 20.5 34.2 68.2 88.1 + + Hours 12 A.M. 2 P.M. 4 P.M. 6 P.M. 8 P.M. 10 P.M. + Number of observations 848 858 878 874 878 1,007 + Tension 75.4 71.5 69.1 84.8 102.4 104 + +From this it will be seen that the tension of electricity is at a minimum +at 4 A.M., also, that it rises till 10, falls till 4 P.M., but not as +rapidly, rises till 10, falls again till 4 A.M., or the close of the +meteorological day--having two maxima and minima, as have most of the +phenomena thus far considered. + +In order to see what the connections between these ever-present, daily +phenomena are, and their connection with other phenomena, and that we may +understand their normal conditions, I will trace them approximately in a +diagram (figure 17.) + +The foregoing diagram of the daily phenomena of a summer's day, when no +disturbing causes are in operation, no storm existing within influential +distance, and no unusual intensity or irregular action of any of the +forces present, affords a basis for considering the various phenomena of +the weather in all its changes and conditions. + +It is obvious that the other phenomena do not all depend upon temperature +merely, if indeed any of them do. + +Temperature has but one maximum and minimum, and that is exceedingly +regular, and does not correspond with any other. + +The barometer has two; electric tension, two; magnetic activity, two; +condensation, two--one the formation of cloud, and the other the formation +of fog and dew; wind, one--resembling temperature in that respect, but +embracing a much less period. + +Fog forms at one barometric minimum, and cloud at another. + +Fog forms at one period of the magnetic variation, cloud at another. + +The formation of cloud corresponds with the greatest intensity of magnetic +action, and its associate electricities. But the oscillations of the +barometer do not correspond with either. And thus, then, we connect them: + + CAUSE. | EFFECT. | EFFECT. + | | + Increase of magnetic|Decrease of pressure. |Increase of primary + or magneto-electric | |condensation. + activity, as shown |Of positive electric | + by declination and |tension. |Of wind. + increase of | | + horizontal and |Of surface condensation,|Of electrical disturbance + vertical force. |_i. e._, fog and dew. |and phenomena in the + | |trade and its vicinity. + +This connection is equally obvious if the order is reversed--thus; + + CAUSE. | EFFECT. | EFFECT. + | | + Decrease of magnetic|Increase of pressure. |Disappearance of primary + or magneto-electric | |condensation. + activity. |Of tension of | + |atmospheric electricity.|Of wind, and + | | + |Of surface condensation,|Of electric disturbance + |_i. e._, fog and dew. |in the trade and its + | |vicinity. + +If we examine still more particularly the different phenomena, we shall +find the same relative action of the forces carried into all the +atmospheric conditions, however violent. + +1. The barometer falls when horizontal magnetic force, and a tendency to +cloud and wind, increase; and rises when they decrease. This corresponds +with the character of the irregular barometric oscillation. Barometric +depressions accompany clouds and winds, and are in proportion to them, and +are all greatest where magnetic force is greatest. The barometer also +rises as the magnetic energy decreases. Do the magnetic currents, passing +upward with increased force, lift, elevate the atmosphere? How, then, are +we to explain the increased range of the oscillations, as the center of +atmospheric machinery is reached, where magnetism has least intensity, and +the perpendicular currents are less, and attraction is less? Attraction is +greatest where intensity is greatest, and there the barometer stands +highest, and the diurnal range is least. Is it then the attraction of +magnetism which produces the barometric oscillations? If so, how then can +we explain the diurnal fall while magnetism is most active? + +Perhaps we have not yet arrived at such a knowledge of the nature of +magnetism as is necessary to a correct answer of those questions. Faraday +has taught us that the lines of magnetic force are close curves, passing +into the atmosphere, and over to the opposite hemisphere, and returning +through the earth, out on the opposite side in like manner, and back +again, passing twice through the earth and twice through the atmosphere. +All we know of this is what the iron filings indicate, and we do not know +how much reliance to place upon the indications they give. But if Faraday +is right, the sun will, twice each day, intersect and stimulate into +increased activity the same closed magnetic curve--once when it is coming +out of the earth, during our day, when its influence will be the most +active, and once when it is returning on the opposite side of the earth; +and a second, but feebler magnetic and electric maximum, may be occasioned +by its action on the opposite and returning closed curve of the same +current. However this may be, it is exceedingly difficult to conceive, of +any adequate influence exerted by the tension of vapor. + +So the mid-day barometric minimum may be caused by the attraction of the +earth, in a state of increased magnetic activity and intensity, upon the +counter-trade, and its consequent approach or settling toward the earth. +Observation, as I have already said, pointedly indicates such a state of +things. So the increased magnetic activity, with or by its associate +electricity, acts upon the electricity of the counter-trade, condensation +takes place, the electricity is disturbed in the surface-atmosphere, by +induction, and its tension is changed. Opposite electrical conditions are +induced in the surface strata, and attraction takes place. The air moves +easily, and thus the attractions originate the winds. Secondary currents +are induced, as in all other cases of electric activity, and winds, in +_different strata_ and directions, occur, with or without cumulus, or scud +condensation, according to their activity, and the proportion of moisture +of evaporation they may contain. + +I am well aware that the various received theories of meteorology +attribute condensation to the action of cold, mingling of colder strata, +etc. But I think that view will have to be abandoned. + +It assumes that moisture is evaporated and held in the atmosphere by +latent heat, which is given out during condensation, and actually warms +the surrounding atmosphere. Thus, the Kew Committee undertook to explain +the development of greater heat, at the elevation where they, in fact, +found the counter-trade. But how unphilosophical to suppose a portion of +the air or vapor contained in it, can give out to another adjoining +portion _more heat than is necessary to produce an equilibrium_. This can, +indeed, be done by experiment--_but the experiment is made with currents +of electricity_. How unphilosophical, too, to talk of latent heat in +connection with evaporation, _at the lowest temperature known_. +Meteorologists must revise their opinions on the subject of condensation. +This latent heat has never been actually met with; on the contrary, the +most sudden and complete condensations of the vapor of the atmosphere are +attended by as sudden and extraordinary productions of cold, and +consequent hail, and the connection between condensation and electricity +is shown by too many facts to permit the old theory to stand. + +_Fog never forms with the thermometer below 32 deg.._ It is mainly a _summer +condensation_, especially high fog. It has been attributed to the cooling +effect of an atmosphere colder than the earth, but it often occurs when +the earth is the coldest, and when the vapor, as it rises, is colder than +the air, and could not give out heat to a warmer medium. (See American +Journal of Science, vol. xliv. p. 40.) Again, it is not mere condensation, +but a formation of globules or vesicles, hollow, and the air expanded in +them, by means of which they float like a soap bubble which contains the +warm air of the breath. Is not every vesicle a model shower, positively +electrified on the outside, negatively in the center, or the reverse, +according to the strata, with the air expanded in the middle by the excess +of heat which negative electricity detains? Look at them, as they attach +themselves to the slender nap of the cloth you wear, when passing through +them, and see how many of them it would require to form a large drop of +rain. The clouds are of a similar vesicular character, and rain does not +fall till the vesicles unite to form drops. Sudden and extreme cold is +indeed produced in the hail-storm, when, above, below, and around it, the +temperature is unaffected. Testu, Wise, and other aeronauts, have so found +it, and the hail tells us it is so. But it is idle to say it results from +radiation. All the phenomena of the sudden, violent hail-storms are +electric in an extraordinary degree. The electricity is disturbed and +separated--the associated heat continues with the negative, and leaves the +positive portion of the cloud, and a corresponding reduction of +temperature results. So Masson found in his eudiometrical analytical +experiments the _negative_ wire would heat to fusion, while the positive +was cold. (See London, Edinburgh, and Dublin Journal of Science for +December, 1853.) This disturbed electricity is diffused over the vesicles. +Listen to the thousand _crackling_ sounds which initiate the clap of +thunder, and may be heard when the lightning strikes near you; produced by +the gathering of the lightning from as many points of the cloud where it +was diffused, to unite in one current and produce the "clap" or +"peal"--and to the "pouring" of the rain, which follows the union of the +vesicles, after the excess of repelling electricity is discharged. + +No _change_ of temperature is observed when fogs form, except the ordinary +change between night and day; and it seems perfectly obvious, in looking +at all the phenomena, that fogs form at a temperature of 70 deg. or 75 deg., in +consequence of the electric influence of the earth upon the adjoining +surface-atmosphere; and, when formed, they withstand the most intense +action of a summer sun, till the time of day arrives for the barometric +and electric tension to fall, condensation to take place in the +counter-trade above, and wind to be induced. Who that has noticed the +almost blistering force of the solar rays, as they break through a section +of high fog, about 10 A.M., can forget them. + +Fogs form near the earth, during the night, when the atmosphere above is +loaded with moisture many degrees colder, and yet remains free from +condensation. On the other hand, during the heat of the day, and of the +hottest days, the heavy rains condense above--nay, they frequently fall at +a temperature of 75 deg. to 80 deg., in the tropics, and of 50 deg. to 55 deg. in +mid-winter here. + +Thus far, an adherence to the opinion that condensation was simply a +cooling process; the driving out of its latent heat, not merely to another +body to make an equilibrium, but "_getting rid of it_" by positive active +radiation, or in some other way, so as to cool off and condense, has +involved the formation and classification of clouds in obscurity. Hopkins +(Atmospheric Changes, p. 331) laments this, but fettered by a false and +imperfect theory, in relation to the tension of vapor, he falls into a +similar error. + +Now, there are, as we have seen, peculiar, distinctly-marked varieties of +cloud, connected with peculiar and distinctly-marked conditions of the +atmosphere, _irrespective of temperature_. None of the theories advanced, +account, or profess to account for the differences in either. No +modification of the calorific theory will account for them. They differ in +shape, in color, in tendency to precipitation, in line of progress, and in +electrical character. The explanation of this is found in the fact, that +they form in distinct and different strata, partake of the positive +electric character of the one, or the negative of the other; or are +secondary, induced by the action of a primary condensation in a different +stratum. There is not any mingling of the different strata, as has been +supposed; and many other facts than those to which we have alluded, show +that the formation of cloud is a magneto-electric process. + +The observations of Reid show that every violent shower cloud has the +electricities disturbed, and portions of it are positive, and others +negative. Howard gives us the following _resume_ of Reid's observations: + + "From an attentive examination of Reid's observations I have been + able to deduce the following general results: + + "1. _The positive electricity, common to fair weather, often yields + to a negative state before rain._ + + "2. _In general, the rain that first falls, after a depression of the + barometer, is_ NEGATIVE. + + "3. _Above forty cases of rain, in one hundred, give negative_ + electricity; although the state of the atmosphere is positive, before + and afterward. + + "4. _Positive rain, in a positive atmosphere, occurs more rarely_: + perhaps fifteen times in one hundred. + + "5. _Snow and hail, unmixed with rain, are positive, almost without + exception._ + + "6. _Nearly forty cases of rain, in one hundred, affected the + apparatus with both kinds_ of electricity; sometimes with an + interval, in which no rain fell; and so, that a positive shower was + succeeded by a negative; and, _vice versa_; at others, the two kinds + alternately took place during the same shower; and, it should seem, + _with a space of non-electric rain between them_." + +Howard attributes, with great apparent probability, the successive +differences in the electrical character of the rain, to the passage of +different portions of the cloud, having different polarity, over the place +of observation. So _positive hail_, and _negative rain_ fall in _parallel +bands_ from the same cloud. Many such instances are on record. It should +be remembered that he is describing the phenomena in the showery climate +of England. + +But the most decisive, perhaps, as well as practically important evidence +of the influence of magnetism, or magneto-electricity, in meteorological +phenomena, is derived from the action of storms. My observation has been +limited, for my life has been, and must be, a practical one. But, subject +to future, and I hope speedy corroboration, or correction, by extensive +systematic observation, I think I may venture to divide all storms into +four kinds: + +1. Those which come to us from the tropics, and constitute the class +investigated by Mr. Redfield. That these are of a magneto-electric +character is evident. They originate near the line of magnetic intensity, +over, or in the vicinity of, the volcanic islands of the tropics; are +largely accompanied by electrical phenomena; extend laterally as they +progress north; induce and create a change of temperature in advance of +them, and do not abate until they pass off over the Atlantic to the E. or +N. E., and perhaps not until they reach the Arctic circle. Their extensive +and continued action is not owing to any mere _mechanical agency_ of the +adjoining passive air, or other supposed currents, originated, no man can +tell how, but they concentrate upon themselves the local magnetic currents +as they pass over and intersect them, and, by their inductive action upon +the surface-atmosphere, in different directions, attract it under them, +and within their more active influence. Here the action of the magnetic +currents is probably the primary cause, but the power of the storm to +concentrate upon itself the new magnetic currents which it intersects as +it enters each new, successive field, enables them to maintain and extend +their action. + +The following diagram illustrates the course and gradual enlargement of a +mid-autumn tropical storm, which induces a S. E. wind in front, and +occasions a thaw. + + +[Illustration: Fig. 20.] + + +2. Another class originate at the N. W., and extend gradually south +easterly on the magnetic meridian. These are most frequent in summer, +forming belts of showers, but occur, I believe, at all seasons of the +year. They seem to be produced by magnetic waves passing south, and are +followed in autumn and winter, and sometimes in summer, by the peculiar N. +W. wind and scud, and a term of cooler weather. + +Thus, it is believed that many, perhaps all of the alternating terms of +heat and cold, are dependent on magnetic waves passing over the country in +a similar manner, with a greater or less belt of condensation between +them, and depending on peculiar magnetic action traveling in the same +way. The S. E. extension of showers and storms, and the cooler changes of +temperature which immediately follow them; with light N. W. wind in +mid-summer, and with it fresher at earlier and later periods, in the form +of northers blowing violently, according to the season, are intimately +connected, and indicate such waves. The indication is strengthened also by +the frequent progress of auroras in like manner, occurring usually after +the belt of condensation has passed, and frequently following it. The +clouds and currents of the atmosphere, so far as I have been able to +discover, show no permanent current from the pole to the atmospheric +equator, compensating for the counter-trade; and that compensation is +furnished by the periodical but frequent atmospheric waves, connected with +the periodical changes of storm, and cloud, and sunshine, which gradually +extend from north to south, in or near the magnetic meridian. Perhaps such +compensating currents are found west of the magnetic poles, as we have +suggested, and make the N. E. and northerly dry winds of Western Europe +and the Pacific; but, in the present state of our knowledge, it is +impossible to say that they are. If it be so, the compensation they +furnish must be small; for the volume of counter-trade which is not +depolarized before it reaches the Arctic circle, and which passes round +the magnetic pole, must be very small. A majority of our periodical +changes, during the northern transit, and I believe at all seasons, are of +this character; and, I have reason to believe, from observation, in one +or two cases, that where belts of rains and showers begin, over _any +locality_ in the United States, they may assume this character. I have +been in Saratoga when an easterly storm commenced _south of that place_; +the condensation and mackerel sky being visible at the south, and no cloud +formation or rain occurring there at the time, and have traced it +afterward as a belt which had a lateral extension south-eastward. Leaving +that place immediately after a belt had passed south, I have overtaken it +by railroad, and run into it again before arriving at New York; and +witnessed its subsequent extension south-eastwardly, out over the +Atlantic. I have witnessed the approach of such a belt in the spring, at +Sandusky, upon Lake Erie, and its passage over to the S. E., followed by +the N. W. wind, as Mr. Bassnett describes them at Ottawa, and run under +the attenuated edge of the same belt, on the same day, on the way to +Pittsburg, leaving the N. W. wind behind, but finding it present again +with clear sky on the following morning. I have seen hundreds of them +approach from the north, and pass to S. E., out over the Atlantic; +followed by the N. W. wind in spring and autumn. This class of storms pass +off toward, and doubtless over the track, of our European steamers and +packets. I know this, for I witness it nearly every month in the year. It +is not a matter of speculation, but of actual, long-continued observation. +Probably, as one approaches the Gulf Stream, and when over it, its induced +winds may be more violent. It is time our navigators understood this; and +that all the gales of the North Atlantic, certainly, are not rotary; and +do not approach from the S. W. in the same manner as the class +investigated by Mr. Redfield do. Where a fresh southerly or south-westerly +wind is followed by any considerable cirro-stratus or stratus-condensation, +it is usually of this character. + +The following diagram exhibits the peculiarities of this class of storms. +It is intended to represent the same storm or belt of showers, on _two +successive_ days, and, of course, its usual rate of southerly extension: + + +[Illustration: Fig. 21.] + + +This class of storms, or belts of showers, present the following +succession of phenomena in summer: + +1. Still warm weather, one or more days. + +2. Fresh southerly wind, one or more days; if more than one, dying away at +the S. W., at night-fall, but continuing into the evening of the day +before the belt of condensation arrives. + +3. Belt of condensation, with or without rain or showers, with the +easterly wind blowing axially, if the condensation is heavy and the belt +wide; westerly if the condensation is feeble or the belt narrow--the +clouds moving about E. N. E. + +4. Cooler air, light N. W. in summer, heavy N. W. in autumn, winter, and +spring. + +And, the next period-- + +5. Still warm weather or light airs. + +6. Southerly wind, fresh. + +7. Belt of condensation. + +8. Cool northerly wind. + +And so on, successively, unless broken in upon by some other class. + +Sometimes these periods are exceedingly regular, at other times the other +classes prevail. I have much reason to believe that this is the _normal, +periodic_ provision for condensation of our portion of the northern +hemisphere, and probably of every other where rain falls regularly in the +summer season, and that the other classes are exceptions, as the +hurricanes are exceptions to the normal condition of the weather every +where. Perhaps in some seasons, during the northern transit, the +exceptions may equal the rule, but I do not now remember such a season. In +other years nearly all the storms are of this character. Thus, Dr. +Hildreth (in Silliman's Journal for 1827), speaking of the year 1826, in a +note to his register of that year, says: "There have been, this year, an +unusual number of winds from N. or N. W. Nearly every rain the past summer +has been followed with winds from the northward, when, in many previous +summers, the wind continued to the southward after rain." The immediate +occurrence of northerly wind after the passage of the belt of +condensation, is a peculiar feature of this class of storms. + +As this also will be new, and is of great practical interest, I shall be +pardoned for referring to other evidence. Bermuda is in latitude 32 deg. +north. In the summer season they are within the range of the Calms of +Cancer, as Lieutenant Maury terms them, and not subject to storms. From +November to May, inclusive, they have successions of revolving wind. +Colonel Reid gave them much attention, and studied them barometrically: +that is, he studied the changes of the wind during the successive periodic +depressions. He found them revolving like ours, and hence inferred the +truth of the gyratory theory in relation to all winds. But it is perfectly +evident the same polar belts which pass over us reach them during the +southern transit. The precedent southerly wind, the _central +condensation_, the appearance of lightning, and the rotation of the wind +by both the east and west, but most frequently by west, are the same. In +his chapter on observations at the Bermudas, he gives us many examples. +Probably the existence of the Gulf Stream to the west and north has a +modifying influence upon them, and their action becomes less intense in +that latitude, but they are very similar. I copy a record of the weather, +for a month, which may be found on pages 252, 253, and 254, and a portion +of his remarks: + + "The month of December, 1839, presents a continual succession of + revolving winds passing over the Bermudas, with scarcely an + irregularity, as regards the fall and rise of the barometer + accompanying the veering of the wind. One, however, occurred on the + 10th and 11th. The S. W. wind abated, and changed to W. N. W., with + the barometer still falling. But in the column of remarks it is noted + that there was lightning seen in the N. and N. W., from 7 P.M., + during the night. This irregularity may, therefore, have been + occasioned by a gale passing over the banks of Newfoundland, + influencing the direction of the wind at Bermuda. + +"REVOLVING WINDS. + + +-----------------------------------------------------------------+ + | Date. | Hour. |Direction of| Wind's | Weather. | Bar.|Ther.| + | | | Wind. | Force. | | | | + |--------|---------|------------|--------|-----------|------|-----| + | 1839. | | | | | | | + |Nov. 30 |Midnight.| S. S. E. | 1 |b. c. | 30.06| 65 | + |Dec. 1 | Noon. | S. S. W. | 3 |b. c. | 30.07| 71 | + | 2 | " | S. W. | 5 |g. m. q. | 29.86| 70 | + | 3 | " | S. S. W. | 3 |g. c. | 29.76| " | + | 4 | " | S. W. | 6 |g. m. r. | 29.62| 68 | + | 5 | " | W. N. W. | 5 |p. q. | 29.56| " | + | 6 | " | N. W. | 6 |p. q. |*29.55| " | + | 7 | " | N. N. W. | 5 |b. c. | 29.78| 70 | + | " |Midnight.| N. N. W. | 3 |b. c. | 29.89| 68 | + | 8 | Noon. | W. N. W. | 2 |b. c. | 29.82| 71 | + | 9 | " | S. S. W. | 5 |p. q. | 29.84| 70 | + | 10 | " | S. W. | 2 |b. c. | 29.96| " | + | 11 | " | W. N. W. | 6 |b. c. m. |*29.88| 68 | + | 12 | " | S. S. W. | " |b. v. | 29.99| 69 | + | 13 | " | N. N. by W.| " |b. v. | 30.01| 66 | + | 14 | " | N. N. W. | 5 |b. c. v. | 30.06| 64 | + | " |Midnight.| N. W. | 2 |b. c. p. | 30.05| 63 | + | 15 | Noon. | S. W. by S.| 6 |g. m. r. | 29.72| 65 | + | " | P.M. 2 | S. S. W. | 7 |m. q. r. | 29.92| 64 | + | " | " 4 | S. S. W. | " |g. m. q. r.| 29.55| " | + | " | " 6 | W. S. W. | " |q. w. |*29.53| " | + | " | " 8 | N. W. | 6 |b. c. q. | 29.54| " | + | " | " 10 | N. N. W. | " |b. c. | 29.55| " | + | 16 | Noon. | N. W. | 7 |b. c. m. | 29.53| 62 | + | 17 | " | N. W. by N.| " |p. q. | 29.67| 60 | + | 18 | " | N. W. | 6 |c. q. | 29.86| " | + | 19 | " | N. W. by N.| 7 |m. q. r. |*29.73| 59 | + | 20 | " | N. N. W. | " |p. q. c. | 29.89| 58 | + | 21 | " | N. W. by N.| 6 |c. q. | 29.96| 56 | + | " |Midnight.| S. W. | 1 |b. c. | 29.95| 55 | + | 22 | Dawn. | ---- | 0 | | | | + | " | Noon. | S. S. W. | 5 |g. m. | 29.83| 56 | + | " | P.M. 4 | S. | 7 |g. m. | 29.79| " | + | " | " 6 | S. S. E. | " |g. m. r. | 29.61| " | + | " | " 8 | S. S. E. | " |w. r. | 29.52| " | + | " | " 10 | S. E. | " |m. w. r. | 29.48| " | + | 23 | Noon. | S. W. | 6 |b. c. m. |*29.44| 57 | + | 24 | " | W. N. W. | " |b. m. | 29.71| 59 | + | 25 | " | W. N. W. | 5 |b. c. | 29.88| 56 | + | 26 | " | N. | 3 |c. | 30.09| 62 | + | 27 | " | S. E. | 5 |c. q. r. | 30.07| 61 | + | 28 | " | S. W. | 6 |c. q. | 29.88| 66 | + | " |Midnight.| S. S. W. | " |b. c. | 29.76| 65 | + | 29 | Noon. | S. W. | 7 |c. b. |*29.48| 64 | + | 30 | " | W. N. W. | 6 |b. c. q. | 29.83| 55 | + | 31 | " | N. W. | 5 |b. c. | 30.12| 58 | + +-----------------------------------------------------------------+ + + "_Remark printed in the Register._ + + "The changes of the wind during the December gales have been nearly + the same in all: _i. e._, commencing with a southerly wind at first, + the wind has veered by the west, toward the north-west, sometimes + ending as far round as N. N. W." + +These extracts show the passage of several successive belts, each with the +phenomena in regular order. + +The first commences with blue sky and detached clouds, barometer up, +thermometer down to 65 deg., and nearly calm, on the 30th of November. + +Dec. 1 (at noon). Wind freshens from S. S. W.; thermometer rises; +barometer still up. + +Dec. 2. Barometer has fallen; thermometer up; wind increasing from S. W., +with gloomy, squally appearance. + +Dec. 3. Wind S. S. W.; barometer slowly falling; thermometer slightly. + +Dec. 4. Wind fresh; S. W.; condensation and rain has reached them, and it +carries barometer and thermometer down. + +Dec. 5. Wind shifting by the west, and squally. + +Dec. 6. Winds gets N. W.; blows fresh; barometer at its minimum, probably +at the time of the change of wind, although the register does not show the +precise time. + +Dec. 7. Wind N. N. W.; blue sky and detached clouds (N. W. scud), cleared +off; barometer elevated by the N. W. wind, from 29.55 to 29.78. Midnight: +blue sky; detached clouds (N. W. scud probably); barometer up to 29.89; +thermometer fallen, from the cooler character of the northerly wind. + +Dec. 8. Wind having lulled as a northerly wind has got round to S. W. +again; thermometer up; barometer falling, and another belt approaching, +and so on. + +The first and last part of December show each two regular occurrences of +substantially the same phenomena. The middle is somewhat more irregular. + +There were five distinctly-marked periods, and one squally, long-continued +period, with a slight tendency to condensation, and a slight fall of +barometer and rain on the 19th (N. W. squall probably), but not sufficient +to reverse the wind to the south. In Colonel Reid's opinion there were +five revolving gales which passed over Bermuda during the month. In my +opinion, there were five perfect polar waves of condensation, and one +imperfect one, with as many successive southerly winds preceding the +condensation, with or without rain in the center, followed by as many cold +N. W. or N. N. W. winds, with squalls, in the rear, about five days apart. +(See the * in the barometric column.) + +_We are at issue._ Let the question be determined by _actual observation_, +and not by _speculation_. It is of fundamental and exceeding importance to +the science. + +Now, let us take a month in summer, from the observations of Mr. Bassnett, +at Ottawa. Here the climate differs somewhat from that east of the +Alleghanies; the magnetic intensity is greater, and the action more +violent and irregular. That part of the country, it should be remembered, +has a greater fall of rain in summer, for reasons we have stated, and +those periodic revolutions are more frequent. + + "A brief abstract from a journal of the weather for one sidereal + period of the moon, in 1853. + + "_June_ 21st. Fine clear morning (S. fresh): noon very warm 88 deg.; 4 + P.M., plumous _cirri in south_; ends clear. + + "22d. Hazy morning (S. very fresh) arch of cirrus in west; 2 P.M., + black in W. N. W.; 3 P.M., overcast and rainy; 4 P.M., a heavy gust + from south; 4.30 P.M., blowing furiously (S. by W.); 5 P.M., + tremendous squall, uprooting trees and scattering chimneys; 6 P.M., + more moderate (W.). + + "23d. Clearing up (N. W.); 8 A.M., quite clear; 11 A.M., bands of + mottled cirri pointing N. E. and S. W., ends cold (W. N. W.); the + cirri seem to rotate from left to right, or with the sun. + + "24th. Fine clear, cool day, begins and ends (N. W.). + + "25th. Clear morning (N. W. light); 2 P.M. (E.), calm; tufts of + tangled cirri in north, intermixed with radiating streaks, all + passing eastward; ends clear. + + "26th. Hazy morning (S. E.), cloudy; noon, a heavy, windy-looking + bank in north (S. fresh), with dense cirrus fringe above, on its + upper edge; clear in S. + + "27th. Clear, warm (W.); bank in north; noon bank covered all the + northern sky, and fresh breeze; 10 P.M., a few flashes to the + northward. + + "28th. Uniform dense cirro-stratus (S. fresh); noon showers all + round; 2 P.M., a heavy squall of wind, with thunder and rain (S. W. + to N. W.); 8 P.M., a line of heavy cumuli in south; 8.30 P.M., a very + bright and high cumulus in S. W., protruding through a layer of dark + stratus; 8.50 P.M., the cloud bearing E. by S., with three rays of + electric light. + + "29th. A stationary stratus over all (S. W. light); clear at night, + but distant lightning in S. + + "30th. Stratus clouds (N. E. almost calm); 8 A.M., raining gently; 3 + P.M., stratus passing off to S.; 8 P.M., clear, pleasant. + + "_July_ 1st. Fine and clear; 8 A.M., cirrus in sheets, curls, wisps, + and gauzy wreaths, with patches beneath of darker shade, all nearly + motionless; close and warm (N. E.); a long, low bank of haze in S., + with one large cumulus in S. W., but very distant. + + "2d. At 5 A.M., overcast generally, with hazy clouds and fog of + prismatic shades, chiefly greenish-yellow; 7 A.M. (S. S. E. + freshening), thick in W.; 8 A.M. (S. fresh), much cirrus, thick and + gloomy; 9 A.M., a clap of thunder, and clouds hurrying to N.; a + reddish haze all around; at noon the margin of a line of + yellowish-red cumuli just visible above a gloomy-looking bank of haze + in N. N. W. (S. very fresh); warm, 86 deg.; more cumuli in N. W.; the + whole line of cumuli N. are separated from the clouds south by a + clearer space. These clouds are borne rapidly past the zenith, but + never get into the clear space--they seem to melt or to be turned off + N. E. The cumuli in N. and N. W., slowly spreading E. and S.; 3 P.M., + the bank hidden by small cumuli; 4 P.M., very thick in north, + magnificent cumuli visible sometimes through the breaks, and beyond + them a dark, watery back-ground (S. strong); 4.30 P.M., wind round to + N. W. in a severe squall; 5 P.M., heavy rain, with thunder, etc.--all + this time there is a bright sky in the south visible through the rain + 15 deg. high; 7 P.M., clearing (S. W. mod.). + + "3d. Very fine and clear (N. W.); noon, a line of large cumuli in N., + and dark lines of stratus below, the cumuli moving eastward; 6 P.M., + their altitude 2 deg. 40'. Velocity, 1 deg. per minute; 9 P.M., much + lightning in the bank north. + + "4th. 6 A.M., a line of small cumulo-stratus, extending east and + west, with a clear horizon north and south 10 deg. high. This band seems + to have been thrown off by the central yesterday, as it moves slowly + south, preserving its parallelism, although the clouds composing it + move eastward. Fine and cool all day (N. W. mod.)--lightning in N. + + "5th. Cloudy (N. almost calm), thick in E., clear in W.; same all + day. + + "6th. Fine and clear (E. light); small cumuli at noon; clear night. + + "7th. Warm (S. E. light); cirrus bank N. W.; noon (S.) thickening in + N.; 6 P.M., hazy but fine; 8 P.M., lightning in N.; 10 P.M., the + lightning shows a heavy line of cumuli along the northern horizon; + calm and very dark, and incessant lightning in N. + + "8th. Last night after midnight commencing raining, slowly and + steadily, but leaving a line of lighter sky south; much lightning all + night, but little thunder. + + "8th. 6 A.M., very low scud (500 feet high) driving south, still calm + below (N. light); 10 A.M., clearing a little; a bank north, with + cirrus spreading south; same all day; 9 P.M., wind freshening (N. + stormy); heavy cumuli visible in S.; 10.30 P.M., quite clear, but a + dense watery haze obscuring the stars; 12 P.M., again overcast; much + lightning in S. and N. W. + + "9th. Last night (2 A.M. of 9th) squall from N. W. very black; 4 + A.M., still raining and blowing hard, the sky a perfect blaze, but + very few flashes reach the ground; 7 A.M., raining hard; 8 A.M. (N. + W. strong); a constant roll of thunder; noon (N. E.); 2 P.M. (N.); 4 + P.M., clearing; 8 P.M., a line of heavy cumuli in S., but clear in N. + W., N., and N. E. + + "10th. 3 A.M., Overcast, and much lightning in south (N. mod.); 7 + A.M., clear except in south; 6 P.M. (E.); 10 P.M., lightning south; + 11 P.M., auroral rays long, but faint, converging to a point between + Epsilon Virginis and Denebola, in west; low down in west, thick with + haze; on the north the rays converged to a point still lower; + lightning still visible in south. This is an aurora in the west. + + "11th. Fine, clear morning (N. E.); same all day; no lightning + visible to-night, but a bank of clouds low down in south, 2 deg. high, + and streaks of dark stratus below the upper margin. + + "12th. Fine and clear (N. E.); noon, a well-defined arch in S. W., + rising slowly; the bank yellowish, with prismatic shades of + greenish-yellow on its borders. This is the O. A. At 6 P.M., the bank + spreading to the northward. At 9 P.M., thick bank of haze in north, + with bright auroral margin; one heavy pyramid of light passed through + Cassiopeia, traveling _westward_ 1-1/2 deg. per minute. This moves to the + other side of the pole, but not more inclined toward it than is due + to prospective, if the shaft is very long; 11.10 P.M., saw a mass of + light more diffuse due east, reaching to _Markab_, then on the prime + vertical. It appears evident this is seen in profile, as it inclines + downward at an angle of 10 deg. or 12 deg. from the perpendicular. It does + not seem very distant. 12 P.M., the aurora still bright, but the + brightest part is now west of the pole, before it was east. + + "13th. 6 A.M., clear, east and north; bank of cirrus in N. W., _i. + e._, from N. N. E. to W. by S.; irregular branches of cirrus clouds, + reaching almost to south-eastern horizon; wind changed (S. E. fresh); + 8 A.M., the sky a perfect picture; heavy regular shafts of dense + cirrus radiating all around, and diverging from a thick nucleus in + north-west, the spaces between being of clear, blue sky. The shafts + are rotating from north to south, the nucleus advancing eastward. + + "At noon (same day), getting thicker (S. E. very fresh); 6 P.M., moon + on meridian, a prismatic gloom in south, and very thick stratus of + all shades; 9 P.M., very gloomy; wind stronger (S. E.); 10 P.M., very + black in south, and overcast generally. + + "14th. Last night, above 12 P.M., commenced raining; 3 A.M., rained + steadily; 7 A.M., same weather; 8.20 A.M., a line of low storm-cloud, + or scud, showing very sharp and white on the dark back-ground all + along the southern sky. This line continues until noon, about 10 deg. at + the highest, showing the northern boundary of the storm to the + southward; 8 P.M., same bank visible, although in rapid motion + eastward; same time clear overhead, with cirrus fringe pointing north + from the bank; much lightning in south (W. fresh); so ends. + + "15th. Last night a black squall from N. W. passed south without + rain; at 3 A.M., clear above but, very black in south (calm below all + the time); 9 A.M., the bank in south again throwing off rays of cirri + in a well-defined arch, whose vortex is south; these pass east, but + continue to form and preserve their linear direction to the north; no + lightning in south to-night. + + "16th. Clear all day, without a stain, and calm. + + "17th. Fine and clear (N. E. light); 6 P.M., calm. + + "18th. Fair and cloudy (N. E. light); 6 P.M., calm. + + "19th. Fine and clear (N. fresh); I. V. visible in S. W. + + "20th. 8 A.M., bank in N. W., with beautiful cirrus radiations; 10 + A.M., getting thick, with dense plates of cream-colored cirrus + visible through the breaks; gloomy looking all day (N. E. light)." + +The letters in a parenthesis signify the direction of the wind. + +During this month there were three distinctly marked periods of belts of +showers, preceded by "fresh" or "strong" south wind, and followed by the +N. W. There was a period when a belt of less intense stratus, without much +wind, occurred (28th, 29th, and 30th of June). This was followed by a +distinct belt of showers and _fresh_ S. wind, on the 2d of July, and by +the N. W. wind and clear weather, on the 3d. + +During the rest of July it was more irregular, with the exception of the +7th, 8th, and 9th, when another belt and revolution occurred. + +Now, these periods, when distinctly marked, exhibit the same succession of +phenomena--viz., elevation of temperature, fresh southerly wind, belt of +condensation, cumulus or stratus with cirrus running east, but extending +south, followed by N. W. wind, and clear, cold air. Can any one believe +they were successive rotary gales? + +I wish, in this connection, to make a suggestion to Lieutenant Maury and +others. The descriptions of M. Bassnett, although not perfect, are very +intelligible. He describes things as they were, and as they should be +described. He distinguishes the clouds, and the scud, and other +appearances. + +But Colonel Reid's descriptions are unmeaning and unintelligible. G. +M.--Gloomy, misty! Gloomy from what? fog, or stratus, or a stratum of +scud, or what? We can not know. Again, C. The table tells us this stands +for detached clouds. But of what kind? Cumulus, broken stratus, patches of +cirro-cumulus or cirro-stratus, or scud? All these, and indeed every kind +of cloud or fog formation, except low fog, may exist in detached portions. + +These abbreviations will not answer; they do not describe the weather. The +clouds must be studied and described. There is no difficulty in doing it. +Sailors will learn them very soon after their teachers have; and those who +teach them should see to it that the logs contain terms of description +which convey the meaning which may, and ought to be, conveyed. The use of +these indefinite terms can not be continued without culpability. + +Again, the observations of seamen off our coast are in accordance with the +progress of this class of storms on land, and prove that they continue S. +E. over the Atlantic, abating in action as they approach the tropics. +There is abundant evidence of this in the work of Colonel Reid, and the +charts of Lieutenant Maury, but I can not devote further space to them. + +The third class form in the counter-trade, over some portion of the +country, from excessive volume or action of the counter-trade, or local +magnetic activity, without coming from the tropics or being connected with +a regular polar wave of magnetic disturbance. + +The following diagram exhibits their form, progress, and accompanying +induced winds. + + +[Illustration: Fig. 22.] + + +The gentle rains of spring, particularly April, and the moderate and +frequent snow-storms of winter, are often of this character; and so are +the heavy rains, which commence at the morning barometric minimum, rain +heavily through the forenoon, and light up near mid-day in the south, +followed by gentle, warm, S. W. winds. This class are more frequent in +some years than others--probably the early years of the decade, while +polar storms are, during the later ones. It is this class which have +_violent_ easterly winds _in front_, and on the _south side_, with two or +more currents, and which Mr. Redfield has also supposed to be cyclones. + +The fourth class are isolated showers, occurring over particular +localities, or belts of drought and showers alternating; sometimes a +general disposition to cloudy and showery weather for a longer or shorter +interval over the whole country; at others, limited to particular +localities in the course of the trade. Such a period occurred during the +wheat harvest of 1855. This class I attribute to a general increased +magnetic action, but it may be induced by an increased volume, or greater +south polar magnetic intensity of the counter-trade, exciting and +concentrating the regular currents of the field, and increasing their +activity and energy. These also often work off south gradually, and are +followed by a cold N. W. air for a day or two; showing a tendency, in the +excited magnetism, to pass as a wave toward the tropics. + +The following diagram will give some idea of this class: + + +[Illustration: Fig. 23.] + + +There are sometimes very obvious local tendencies to precipitation over +portions adjoining an area affected with drought, as there are other +magnetic irregularities over particular areas. + +All these classes of storms are variant in intensity. Sometimes the +general or local cloud-formation is weak, and does not produce +precipitation at all; so of that which extends southerly. Probably the +tropical storm are always sufficiently dense and active to precipitate. +Their action is often violent over particular localities, and hence the +more frequent occurrence of the tornado over the more intense area of +Ohio, and other portions of the west. All violent local storms are +doubtless owing to local magneto-electric activity. + + + + +CHAPTER XI. + + +The reader who has attentively perused and considered the facts stated, +and the principles deduced, in the preceding pages, and is ready to make a +practical application of them by careful observation, will have little +difficulty in understanding the varied atmospheric conditions; and will +soon be able to form a correct judgment of the immediate future of the +weather, so far as his limited horizon will permit. + +But there are other facts and considerations, not specifically alluded to, +which will materially aid him in his observations; and there is a degree +of philosophical truth in the proverbs and signs, which ancient popular +observation accumulated, and poetry and tradition have preserved, that +meteorologists have been slow to discover or admit, but which will be +obvious upon examination, and commend them to his attention. + +The classical reader is doubtless familiar with that part of the first +Georgic of Virgil, which contains a description of the signs indicative of +atmospheric changes. Much of it is beautifully poetic, and, if read in the +light of a correct philosophy, is equally truthful. + +I copy from a creditable translation, found in the first volume of +Howard's "Climate of London": + + "All that the genial year successive brings, + Showers, and the reign of heat, and freezing gales, + Appointed signs foreshow; the Sire of all + Decreed what signs the southern blast should bring, + Decreed the omens of the varying moon: + That hinds, observant of the approaching storm, + Might tend their herds more near the sheltering stall." + + + PROGNOSTICS.--_1st. Of Wind._ + + "When storms are brooding--in the leeward gulf + Dash the swell'd waves; the mighty mountains pour + A harsh, dull murmur; far along the beach + Rolls the deep rushing roar; the whispering grove + Betrays the gathering elemental strife. + Scarce will the billows spare the curved keel; + For swift from open sea the cormorants sweep, + With clamorous croak; the ocean-dwelling coot + Sports on the sand; the hern her marshy haunts + Deserting, soars the lofty clouds above; + And oft, when gales impend, the gliding star + Nightly descends athwart the spangled gloom, + And leaves its fire-wake glowing white behind. + Light chaff and leaflets flitting fill the air, + And sportive feathers circle on the lake." + + + _2d. Of Rain._ + + "But when grim Boreas thunders; when the East + And black-winged West, roll out the sonorous peal, + The teeming dikes o'erflow the wide champaign, + And seamen furl their dripping sails. The shower, + Forsooth, ne'er took the traveler unawares! + The soaring cranes descried it in the vale, + And shunn'd its coming; heifers gazed aloft, + With nostrils wide, drinking the fragrant gale; + Skimm'd the sagacious swallow round the lake, + And croaking frogs renew'd their old complaint. + Oft, too, the ant, from secret chambers, bears + Her eggs--a cherished treasure--o'er the sand, + Along the narrow track her steps have worn. + High vaults the thirsty bow; in wide array + The clamorous rooks from every pasture rise + With serried wings. The varied sea-fowl tribes, + And those that in Caeyster's meadows seek, + Amid the marshy pools, their skulking prey, + Fling the cool plenteous shower upon their wings, + Crouch to the coming wave, sail on its crest, + And idly wash their purity of plume. + The audacious crow, with loud voice, hails the rain + A lonesome wanderer on the thirsty sand. + Maidens that nightly toil the tangled fleece, + Divine the coming tempest; in the lamp + Crackles the oil; the gathering wick grows dim." + + + _3d. Of Fair Weather._ + + "Nor less, by sure prognostics, mayest thou learn + (When rain prevails), in prospect to behold + Warm suns, and cloudless heavens, around thee smile. + Brightly the stars shine forth; Cynthia no more + Glimmers obnoxious to her brother's rays; + Nor fleecy clouds float lightly through the sky. + The chosen birds of Thetis, halcyons, now + Spread not their pinions on the sun-bright shore; + Nor swine the bands unloose, and toss the straw. + The clouds, descending, settle on the plain; + While owls forget to chant their evening song, + But watch the sunset from the topmost ridge. + The merlin swims the liquid sky, sublime, + While for the purple lock the lark atones: + Where she, with light wing, cleaves the yielding air, + Her shrieking fell pursuer follows fierce-- + The dreaded merlin; where the merlin soars, + _Her_ fugitive swift pinion cleaves the air. + And now, from throat compressed, the rook emits, + Treble or fourfold, his clear, piercing cry; + While oft amid their high and leafy roosts, + Bursts the responsive note from all the clan, + Thrill'd with unwonted rapture--oh! 'tis sweet, + When bright'ning hours allow, to seek again + Their tiny offspring, and their dulcet homes. + Yet deem I not, that heaven on them bestows + Foresight, or mind above their lowly fate; + But rather when the changeful climate veers, + Obsequious to the humor of the sky; + When the damp South condenses what was rare, + The dense relaxing--or the stringent North + Rolls back the genial showers, and rules in turn, + The varying impulse fluctuates in their breast: + Hence the full concert in the sprightly mead-- + The bounding flock--the rook's exulting cry." + + + _4th. The Moon's Aspects, etc._ + + "Mark with attentive eye, the rapid sun-- + The varying moon that rolls its monthly round; + So shalt thou count, not vainly, on the morn; + So the bland aspect of the tranquil night + Will ne'er beguile thee with insidious calm. + When Luna first her scatter'd fires recalls, + If with blunt horns she holds the dusky air, + Seamen and swains predict th' abundant shower. + If rosy blushes tinge her maiden cheek, + Wind will arise: the golden Phoebe still + Glows with the wind. If (mark the ominous hour!) + The clear fourth night her lucid disk define, + That day, and all that thence successive spring, + E'en to the finished month, are calm and dry; + And grateful mariners redeem their vows + To Glaucus, Inoeus, or the Nereid nymph." + + + _5th. The Sun's Aspects, etc._ + + "The sun, too, rising, and at that still hour, + When sinks his tranquil beauty in the main, + Will give thee tokens; certain tokens all, + Both those that morning brings, and balmy eve. + When cloudy storms deform the rising orb, + Or streaks of vapor in the midst bisect, + Beware of showers, for then the blasting South + (Foe to the groves, to harvests, and the flock), + Urges, with turbid pressure, from above. + But when, beneath the dawn, red-fingered rays + Through the dense band of clouds diverging, break, + When springs Aurora, pale, from saffron couch, + Ill does the leaf defend the mellowing grape; + Leaps on the noisy roof the plenteous hail, + Fearfully crackling. Nor forget to note, + When Sol departs, his mighty day-task done, + How varied hues oft wander on his brow; + Azure betokens rain: the fiery tint + Is Eurus's herald; if the ruddy blaze + Be dimm'd with spots, then all will wildly rage + With squalls and driving showers: on that fell night, + None shall persuade me on the deep to urge + My perilous course, or quit the sheltering pier. + But if, when day returns, or when retires, + Bright is the orb, then fear no coming rain: + Clear northern airs will fan the quiv'ring grove. + Lastly, the sun will teach th' observant eye + What vesper's hour shall bring; what clearing wind + Shall waft the clouds slow floating--what the South + Broods in his humid breast. Who dare belie + The constant sun?" + +I copy also the following from Howard: + + "Dr. Jenner's signs of rain--an excuse for not accepting the + invitation of a friend to make a _country_ excursion. + + "The hollow winds begin to blow, + The clouds look black, the glass is low, + The soot falls down, the spaniels sleep, + And spiders from their cobwebs creep. + Last night the sun went pale to bed, + The moon in halos hid her head, + The boding shepherd heaves a sigh, + For see! a rainbow spans the sky. + The walls are damp, the ditches smell; + Closed is the pink-eyed pimpernel. + Hark! how the chairs and tables crack; + Old Betty's joints are on the rack. + Loud quack the ducks, the peacocks cry; + The distant hills are looking nigh. + How restless are the snorting swine!-- + The busy flies disturb the kine. + Low o'er the grass the swallow wings; + The cricket, too, how loud it sings! + Puss, on the hearth, with velvet paws, + Sits smoothing o'er her whisker'd jaws. + Through the clear stream the fishes rise + And nimbly catch the incautious flies; + The sheep were seen, at early light, + Cropping the meads with eager bite. + Though _June_, the air is cold and chill; + The mellow blackbird's voice is still; + The glow-worms, numerous and bright, + Illumed the dewy dell last night; + At dusk the squalid toad was seen, + Hopping, crawling, o'er the green. + The frog has lost his yellow vest, + And in a dingy suit is dress'd. + The leech, disturbed, is newly risen + Quite to the summit of his prison. + The whirling wind the dust obey + And in the rapid eddy plays. + My dog, so altered in his taste, + Quits mutton-bones, on grass to feast; + And see yon rooks, how odd their flight! + They imitate the gliding kite: + Or seem precipitate to fall, + As if they felt the piercing ball. + 'Twill surely rain; I see, with sorrow, + Our jaunt must be put off to-morrow." + +Howard attributes the foregoing to Jenner; but Hone, in his "Every-Day +Book," attributes it to Darwin, and gives it, with several couplets, not +found in that attributed to Jenner. These I add from Hone, as follows: + + "Her corns with shooting pains torment her-- + And to her bed untimely send her." + +That couplet is included by Hone with what is said of Aunt Betty. + + "The smoke from chimneys right ascends, + Then spreading back to earth it bends. + The wind unsteady veers around; + Or, settling in the south is found." + +Those are as philosophically accurate and valuable as any. + + "The tender colts on back do lie; + Nor heed the traveler passing by. + In fiery red the sun doth rise, + Then wades through clouds to mount the skies." + +The first of those couplets is untrue. It is doubtless alluded to as one +of the acts of the animal creation, indicating sleepiness and inaction, +which precede storms; but colts do not lie on the back. The other couplet +is both true and important. This collection entire, whether written by +Darwin or Jenner, contains most of the signs which have been preserved, +and which are of much practical importance in our climate. + +It is unquestionably true that "appointed signs foreshow the weather," to +a great extent, every where, but with more certainty in the climate in +which Virgil wrote than in our variable and excessive one. "Showers" and +"freezing gales" we can, perhaps, as well understand; but the "_reign of +heat_," by which he probably meant the dry period, when the southern edge +of the extra-tropical belt of rains is carried up to the north of them, we +do not experience. Something like it we did indeed have, during the +excessive northern transit, in the summer of 1854; but it was an +exception, not the rule. + +Some of the most important of those signs from Virgil and Jenner I propose +to allude to in detail; but it is necessary to look; in the first place, +to the character of the season and the month. + +We have seen that the years differ during different periods of the same +decade. That they incline to be hot and irregular during the early part of +it, and cool, regular, and productive during the latter portion--subject, +however, to occasional exceptions. The latter half of the third decade of +this century (1826 to 1830, inclusive) was comparatively warm; and, in the +latitude of 41 deg., was very unhealthy, and so continued during the early +part of the next, over the hemisphere, embracing the _cholera seasons_. +The spots upon the sun were much less numerous than usual, during the +latter half of the third decade. Thus the spots from + + 1826 to 1830, inclusive, were 873 + 1836 to 1840 " " 1201 + 1846 to 1850 " " 1168 + + and the size of those from 1836 to 1840 exceeded those of the other + years. + +The attentive observer will very soon be satisfied that the seasons have a +character; and those of every year differ in a greater or less degree from +those of other years in the same decade, and those of one decade not +unfrequently from those of some other. _Periodicity_ is stamped upon all +of them, and upon all resulting consequences. Like seasons come round, +and, like productiveness or unproductiveness, healthy or epidemic +diatheses, attend them. We have seen that, in relation to mean +temperature, there are such periodical diversities, but they are more +strongly marked in the character of storms, and other successions of +phenomena. "_All signs fail in a drouth_," for then all attempts at +condensation are partial, imperfect, and ineffectual. "_It rains very +easy_," it is said, at other times, and so it seems to do, and with +comparatively little condensation. In the one case, no great reliance can +be placed upon indications which are entirely reliable in the other. So +"_all our storms clear off cold_," or, "_all our storms clear off warm_," +are equally common expressions--as the _prevailing classes_ of storms give +a _character_ to the _seasons_. It "_rains every Sunday now_," is +sometimes said, and is often peculiarly true--the storm waves having just +then a weekly or semi-weekly period, and one falls upon Sunday for several +successive weeks; and when it is so, _that_ coincidence is sure to be +noticed and commented upon, and the other perhaps disregarded. + +If the seasons depended upon the northward and southward journey of the +sun alone, entire regularity might be expected--for we have no reason to +believe that magnetism and electricity contain, within themselves, +inherently, any tendency to irregularity, or periodicity; and, the sun +being constant in his _periods_, would be constant in his _influence_. But +he is inconstant and variable in his influence, and it is apparently +traceable to the existence of spots; but I am not quite sure that it is +occasioned by the _observable_ spots alone. Grant that the intensity and +power of his rays differ on the same day, in different years, and that +difference may be attributable in part to causes which our telescopes can +not discover. + +But the differences in the seasons do not depend on the variability of the +sun's influence alone. This appears from the frequent meridional and +latitudinal diversities and contrasts, to which allusion has been made. +The sun can not be supposed to exert a _less_ influence on a middle, than +a more northern latitude; nor on one series of meridians, than another. +There must, therefore, be another local and powerful disturbing cause, +varying the magnetic and electric activity and influence upon the trades, +as well in their incipiency as in their circuits, and thus controlling the +atmospheric conditions locally and in _the opposite hemispheres_. That +other disturbing cause is _volcanic action_. We can conceive of none +other, and we can detect and trace the influence of that to a considerable +extent. Unfortunately we know, and can practically know, comparatively +little of it. It has been busy with the earth since the creation, and will +continue to be so till, possibly, by a collision, it shall burst into +asteroids--its molten interior flowing out in seeming combustion--each +fragment retaining its magnetic polarities entire, and continuing on in an +independent orbit in the heavens, an asteroid, or meteorite. + +While, therefore, the agency of magnetism in itself may be regular, and +the transit of the sun is regular, and "seed-time and harvest shall not +cease," yet the sun is not regular in his influence, and the magnetic +agency is disturbed by another and irregular power. And, although we can +trace the influence of both upon the seasons, we can not measure that +influence, and from it reliably foretell the weather. The discoveries of +Swabe, and future ones, relative to solar irregularities, will assist us, +but, till we understand better, and to some extent anticipate, the +changes of volcanic action, we shall not be able to understand or foresee +all the differences in the seasons. That time may come; for progress is +yet to be read in the front of meteorology, and simultaneous practical +observations made and interchanged at every important point on the globe. +Nevertheless, the seasons have a character--often a regular one--one class +of storms prevailing over all others--one series of phenomena occurring to +the exclusion of others--and we must regard it if we would arrive at +intelligent estimates of their future condition. + +The most difficult part to understand are the meridional contrasts. Last +year we had one of the worst drouths which has occurred since the +settlement of the country. But while all the eastern portion of the United +States was dry, New Mexico was unusually wet; and the North-western +States, on the same curving line of the counter-trade, were not affected +by the drouth. + +Extract from a letter written by Governor Merriweather, to Mr. Bennett, in +answer to a circular, published in the "New York Herald," and dated + + "SANTA FE, NEW MEXICO, Oct. 25th, 1854. + + "More rain has fallen during the last six months, within this + territory, than ever was known to have fallen in the same length of + time, in this usually dry climate. Generally, little or no crops have + been produced without irrigation; but this season some good crops + have been produced without any artificial watering." + +We have seen that there was an apparent connection between the remarkable +volcanic action, exerted beneath the western continents during the second +decade of this century, and the remarkable coldness of that decade. And +it is easy to see that the comparative absence of volcanic action from +immediately beneath the Old World, and its presence in great excess +beneath the New, may disturb the regular action of terrestrial magnetism +above it in the earth's-crust here, and affect seasons, diatheses, and +health unfavorably; while from its absence they may be favorably affected +there. I have some general views in relation to this, but they are +necessarily speculative, for the data are few, and I reserve them. + +I am, however, induced to believe that the transit of the atmospheric +machinery is greater over some portions of the northern hemisphere, in +some seasons, than others. The most natural explanation of the unusual +contrast between the drouth of the Eastern States, and the wet of the +Territories, during the last summer, is, that the concentrated +counter-trade was carried west, by some irregular magnetic action in the +South Atlantic or West Indies. But there was much evidence that the +northern extension of the atmospheric machinery was greater than usual. +The transit began _early_--it was evidently _rapid_; the rains of May fell +in April, and the spring was wet; _summer set in earlier_--all the +appearances then were unusually tropical--the polar belts of condensation +descended upon us, but they were feeble, as they doubtless become, when +they reach the tropics, and did not precipitate; the summer continued full +twenty days later--no rain falling till about the 10th of September. The +season throughout was excessive, but otherwise regular. Spring came +earlier; summer commenced earlier and continued longer; autumn held off +later, and cold weather, when it came, was uniform and severe. This season +the transit has seemed to be less than for several years.[10] The spring +was backward; the summer cool, but exceedingly regular; the autumn thus +far without extremes, and the whole year healthy and productive. It is the +normal period of the decade, between the irregular heat of the first part, +and the irregular cold of the last; and it has been normal in character, +and conformed beautifully to its location. If the transit of 1854 was +further north than the mean, as it seemed to be over this country, that of +itself would convey the showers which follow up in the western portion of +the concentrated trade, on the east of the mountains of Mexico, and cause +them to precipitate further north, over New Mexico, and thus, rather than +from a diverted trade, they may have derived their unusual supply of +moisture during the summer of 1854. On this subject I can but conjecture, +and leave to future observation a discovery of the truth. + +Enough appears, however, to show the importance of taking the location of +the year in the decade, and even the character of the decade itself, into +the account. + +But whatever the remote cause of the difference in the seasons, the +character of the seasons is directly influenced by the character of +storms, or periodic changes. Sometimes the tropical storms are most +numerous; at others the polar waves; and at others the irregular local +storms, or general tendency to showers. The seasons when the polar waves +are most prevalent, are the most regular, healthy, and productive. Those +where the tropical tendency is greatest, are irregular; and so are those +where the other classes predominate. These differences in the character of +the storms, are but the varying forms in which magnetic action develops +itself. I have said that there was a decided tendency to cirrus without +cumulus, in mid-winter, and cumulus without cirro-stratus or stratus, in +midsummer, and during the intermediate time an intermediate tendency. But +there is a difference between spring and autumn. Dry westerly (not N. W.) +gales prevail in March, and N. E. storms in April and May, but violent S. +E. gales are not as common. On the other hand, the dry westerly gales of +March are comparatively unknown in autumn, and the violent, tropical, +south-easters are then common. + +Snow-storms occur during the northern transit, not unfrequently in April +and May; but they do not occur so near the acme of the northern transit on +its return; nor until it approaches very near its southern limit. The +quiet, warm, and genial air of April, is reproduced in the Indian summer +of autumn, but they present widely different appearances. Those, and many +other peculiarities of the seasons, deserve the attentive consideration of +every one who would become familiar with the weather and its prognostics. + +These irregularities in the character of the seasons have doubtless always +existed, and always been the objects of popular observation. There are +some very old proverbs which show this. I copy a few of the many, which +may be found in Foster's collection. Mr. Graham Hutchison does not seem to +think any of those ancient proverbs worthy of notice. But he misjudges. +They are the result of popular observation, and many of them accord with +the true philosophy of the weather. + +_Irregular_ seasons are unhealthy, and unreliable for productiveness. When +the southern transit was late, or limited, and the autumn ran into winter, +our ancestors feared the consequences in both particulars, and expressed +their fears, and hopes also, in proverbs. Thus, + + "A green winter + Makes a fat churchyard." + +There is very great truth in this proverb. Again, + + "If the grass grows green in Janiveer, + It will grow the worse for it all the year." + +This is emphatically true, for the season which commences irregularly will +be likely to continue to be irregular in other respects. + +Another of the same tenor: + + "If Janiveer Calends be summerly gay, + It will be winterly weather till Calends of May." + +Janiveer is an alteration of the French name for January, and the proverb +is very old. + +So March should be normally dry and windy. + +This, too, they understood, and hence the strong proverb: + + "A bushel of March _dust_ + Is worth a king's ransom." + +And another: + + "March hack ham, + Come in like a lion, go out like a lamb." + +So April and May should be cool and moist. It is their normal condition in +regular, healthy, and productive seasons. The grass and grain require such +conditions; and the spring rains are needed to supply the excessive summer +evaporation. This, too, they well understood. And hence the proverbs: + + "A cold April the barn will fill." + + "A cool May, and a windy, + Makes a full barn and a findy." + +And-- + + "April and May are the keys of the year." + +This was not very favorable, to be sure, for corn; but their consolation +was found, as we find it, in the truth of another proverb: + + "Look at your corn in May, and you'll come sorrowing away; + Look again in June, and you'll come singing in another tune." + +This difference in the character of the seasons occasioned the adoption of +a great variety of "Almanac days;" and they are still very much regarded. +Candlemas-day (2d of February) was one of them. + +Says Hone, in his "Every-Day Book": + + "Bishop Hall, in a sermon, on Candlemas-day, remarks, that 'it has + been (I say not how true) an old note, that hath been wont to be set + on this day, that if it be clear and sunshiny, it portends hard + weather to come; if cloudy and lowering, a mild and gentle season + ensuing.'" + +To the same effect is one of Ray's proverbs: + + "The hind had as lief see + His wife on her bier, + As that Candlemas-day + Should be pleasant and clear." + +St. Paul's day, or the 25th of January, was another great "Almanac day," +and so the verse: + + "If Saint Paul's day be fair and clear, + It does betide a happy year; + But if it chance to snow or rain, + Then will be dear all kinds of grain. + If clouds or mists do dark the sky, + Great store of birds and beasts shall die; + And if the winds do fly aloft, + Then war shall vex the kingdom oft." + +St. Swithin's day was another of these "Almanac days." Gay said truly, + + "Let no such vulgar tales debase thy mind; + Nor Paul, nor Swithin, rule the clouds or wind." + +Yet "_Almanac days_" are still in vogue to a considerable extent--such as +the _three first days_ of the year, old style--the first three of the +season--the last of the season--different days of the month--of the +lunation, etc., etc. And some still look to the breastbone of a goose, in +the fall, to judge, by its whiteness, whether there is to be much snow +during the Winter, etc. + +These _Almanac days should all be abandoned_; they have no foundation in +philosophy or truth. There is one proverb, however, in relation to +Candlemas-day, which the "oldest inhabitant" will remember, and which it +may be well to retain. It has a practical application for the farmer, and +in relation to the length of the winter: + + "Just half of your wood and half of your hay + Should be remaining on Candlemas-day." + +The months, too, have a character which must be remembered and regarded. + +_January_ is the coldest month of the year, in most localities. The +atmospheric machinery reaches its extreme southern transit, for the +season, during the month--usually about the middle. It remains stationary +a while--usually till after the 10th of February. One or more thaws, +resulting from tropical storms, occur during the month, in normal winters, +but they are of brief duration. Boreas follows close upon the retreating +storm with his icy breath. There is a remarkable uniformity in the +progress of the depression of temperature, to the extreme attained in this +month, over the entire hemisphere. It differs in degree according to +latitude and magnetic intensity; but it progresses to that degree, +whatever it may be, with as great uniformity in a southern as northern +latitude. The table, copied from Dr. Forrey, discloses the fact, and so +does the following one, taken from Mr. Blodget's valuable paper, published +in the Patent Office Report for 1853: + + +TABLE SHOWING THE MEAN TEMPERATURE FOR EACH MONTH AT SEVERAL PLACES, VIZ.: + + +---------------------------------------------------------------------+ + | | Lat. | Jan. | Feb. |March.|April.| May. |June. | + |-------------------|-------|------|------|------|------|------|------| + |Quebec, Canada E. |46 deg. 49'| 9.9 | 12.8 | 24.4 | 38.7 | 52.9 | 63.7 | + |New York, N. Y. |40 deg. 42'| 30.2 | 30.8 | 38.5 | 49.1 | 59.6 | 69.1 | + |Albany, N. Y. |42 deg. 39'| 24.5 | 24.3 | 34.8 | 47.7 | 59.8 | 68.0 | + |Rochester, N. Y. |42 deg. 45'| 26.1 | 25.8 | 33.0 | 45.8 | 56.2 | 64.5 | + |Baltimore, Md. |39 deg. 17'| 33.1 | 34.3 | 42.4 | 53.0 | 63.2 | 71.6 | + |Savannah, Ga. |32 deg. 05'| 52.6 | 54.7 | 60.0 | 68.4 | 74.8 | 79.4 | + |Key West, Fla. |24 deg. 33'| 70.0 | 70.7 | 73.8 | 76.3 | 80.2 | 82.1 | + |Mobile, Ala. |30 deg. 40'| 51.3 | 53.7 | 59.4 | 67.1 | 74.1 | 77.8 | + |New Orleans, La. |30 deg. 00'| 54.8 | 54.5 | 61.5 | 67.6 | 74.0 | 78.6 | + |Marietta, Ohio |39 deg. 25'| 32.2 | 34.1 | 42.6 | 53.0 | 61.8 | 69.2 | + |San Antonio, Tex. |29 deg. 25'| 52.7 | 57.9 | 65.5 | 69.7 | 76.4 | 80.5 | + |San Francisco, Cal.|37 deg. 48'| 50.1 | 51.0 | 53.8 | 57.7 | 55.9 | 58.8 | + +---------------------------------------------------------------------+ + + +-----------------------------------------+ + |July. | Aug. | Sept.| Oct. | Nov. | Dec. | + |------|------|------|------|------|------| + | 66.8 | 65.5 | 56.2 | 44.1 | 31.5 | 17.3 | + | 74.9 | 73.3 | 65.9 | 54.3 | 43.5 | 33.9 | + | 72.2 | 70.3 | 61.4 | 49.2 | 39.4 | 28.3 | + | 69.7 | 67.8 | 60.1 | 47.7 | 38.2 | 28.8 | + | 76.6 | 74.5 | 67.7 | 55.8 | 45.0 | 37.8 | + | 81.3 | 80.6 | 76.9 | 67.2 | 58.3 | 52.2 | + | 83.3 | 83.5 | 82.5 | 79.1 | 75.6 | 72.8 | + | 79.8 | 79.4 | 76.1 | 65.7 | 57.0 | 52.8 | + | 80.4 | 79.6 | 77.1 | 69.1 | 57.5 | 56.2 | + | 72.7 | 70.9 | 63.5 | 51.8 | 42.6 | 34.7 | + | 82.3 | 83.3 | 79.9 | 72.2 | 62.2 | 52.1 | + | 57.9 | 62.2 | 61.6 | 61.9 | 56.2 | 50.0 | + +-----------------------------------------+ + +Snows during this month are much heavier, and more frequent, in some +localities than others. The reasons why this is so have been stated. The +mountainous portions of the country receive the heaviest falls. They +affect condensation somewhat, and according to their elevation. They +intercept the flakes before they melt, and retain them longer without +change. The thaws, or tropical storms, also sometimes have a current of +cold air, with snow setting under them on their northern and north-western +border. Such was the case with that investigated by Professor Loomis. +January is without other marked peculiarities. It shows, of course, those +extremes of temperature found, to a greater or less degree, in all the +months, and differs, as the others differ, in different seasons. Normally, +in temperate latitudes, it is a healthy month. The digestive organs have +recovered from that tendency to bilious diseases which characterizes the +summer extreme northern transit, and the tendency to diseases of the +respiratory organs, which characterizes the southern extreme and the +commencement of its return, is not often developed till February. +February, in its normal condition until after the 10th, and about the +middle, is much like January. Often the first ten days of February are the +coldest of the season. The average of the month is a trifle higher, in +most localities, as the tables show. This results from the increasing +warmth of the latter part of the month. There are localities, however, +where the entire month is as cold as January. Such (as will appear from +Blodget's table) are Albany and Rochester, in the State of New York, and +New Orleans, in Louisiana. At most places the difference is slight, either +way. South of the latitude of 40 deg. heavy snows are more likely to occur in +the last half of January and first half of February than earlier. About +the middle of the month we may expect thaws of more permanence in normal +seasons. They are followed, as in January, by N. W. wind and cold weather, +but it is not usually as severe. Many years since, an observing old man +said to me, "_Winter's back breaks about the middle of February_." And I +have observed that there is usually a yielding of the extreme weather +about that period. Here, again, it is interesting and instructive to look +at the tables, and see how regularly and uniformly the temperature rises +in all latitudes, at the same time; as early and as rapidly at Quebec as +at New Orleans or San Antonio; and subsequently rises with greatest +rapidity where the descent was greatest. The elevation of temperature does +not progress northwardly, a wave of heat accompanying the sun, but is a +magneto-electric change, commencing about the same time over the whole +country, and indeed over the hemisphere. + +March is a peculiar month--the month of what is termed, and aptly termed, +"unsettled weather." It, may "come in like a lion," or be variable at the +outset. The northern transit is fairly started, and is progressing +rapidly, and there is great magnetic irritability. A reference to the +table of Dr. Lamont will show that the declination has increased with +great rapidity. Normally, the early part is like the latter part of +February, and the latter part approaches the milder but still changeable +weather of April. Its distinguishing feature is violent westerly wind. Not +the regular N. W. only--although that is prevalent--but a peculiar +westerly wind, ranging from W. by N. to N. W. by W., often blowing with +hurricane violence. This wind was alluded to on page 130. With the change +and active transit to the north, in February and in March, comes the +tendency to diseases of the respiratory organs--pneumonias and lung +fevers--and this is the most dangerous period of the year for aged people. + +April is a milder and more agreeable month. During some period of it, in +normal seasons, and at other times in March, there is a warm, quiet, +genial, "lamb-"like _spell_, exceedingly favorable for oat seeding. When +it comes, advantage should be taken of it, for long heavy N. E. storms are +liable to occur, and frequently with snow. On the latitude of 41 deg. heavy +snow-storms are not uncommon in April. Within the last fifteen years two +such have occurred after the 10th of the month. April, as we have seen, +should be cool and moist. If dry, the early crops are endangered by a +spring drouth; if very wet, there is danger of an extreme northern +transit, and an early summer drouth. It is emphatically true that + + "April and May are the keys of the year." + +Its distinguishing peculiar feature is the gentle, _warm_, _trade_ +rains--"_April showers_"--which, in the absence of great magnetic +irritability, that current drops upon us. There is great _mean_ magnetic +activity, but it is not so _irregularly excessive_ as in March. + +May, in our climate, should be, and normally is, a wet month, and a cool +one, considering the altitude of the sun. The atmospheric machinery which +the sun moves is, however, ordinarily about six weeks behind it--the +latter reaching the tropic the 20th of June, and the former its farthest +northern extension about six weeks later. Hence it is not a cause for +alarm if May be wet and cool. The great staples, wheat, grass, and oats, +are benefited; and corn, according to the proverb, will not be seriously +retarded. The movable belt of excessive magneto-electric action, with its +tropical electric rains, so exciting to vegetation, and its periods or +terms of excessive heat, is on its way north, and sure to arrive in +season, and remain long enough to mature the corn. There have been but two +seasons in this century when corn did not mature in the latitude of 41 deg.. +One during the cold decade, and the cold part of it, between 1815 and +1820; and the other, during the cold half of the fourth decade, between +1835 and 1840. + +The distinguishing feature, if there be one, of May, is its long, and, for +the season, cool storms. These have, in different localities, different +names. In pastoral sections we hear of the "_sheep storms_"--those which +effect the sheep severely when newly shorn--killing them or reducing them +in flesh by their coldness and severity. + +In relation to this too early shearing, there is an old English proverb, +in "Forster's Collection," viz.: + + "Shear your sheep in May, + And you will shear them all away." + +So there are others called "_Quaker storms_," which occur about the time +when that estimable sect hold their yearly meeting. And there are other +names given in different localities to these long spring storms. But they +are all _mere coincidences_--equinoctial and all. + +Notwithstanding the storms, however, the temperature rises at a mean. The +declination is often as great as in mid-summer. The earth is growing +warmer by the increase of magneto-electric action, whatever the state of +the atmosphere. The yellow, sickly blade of corn is extending its roots +and preparing to "_jump_" when the atmosphere becomes hot, as it is sure +to do, when the machinery attains a sufficient altitude, how backward +soever it may seem to be. The farmer need not mourn over its backwardness, +unless the season is a very extraordinary one, like those of 1816 and +1836. The storms ensure his hay, wheat, and oat crops; the warming earth +is at work with the roots of his corn, and is filling with water, and +preparing for the hot and rapidly-evaporating suns of mid-summer. The +earth would grow warmer if every day was cloudy. + +By the middle of June the atmospheric machinery approaches its northern +acme, the summer sets in, and not unfrequently, as extremely hot days +occur during the latter part of the month, as at any period of the +summer. But the heat is not so continuous, or great, at a mean. + +From the middle of June to the latter part of August is summer in our +climate, and during that period from one to three or four terms of extreme +heat occur, continuing from one to five or six days, and possibly more, +terminating finally in a belt of showers overlaid with more or less +cirro-stratus condensation in the trade, and controlled by the S. E. polar +wave of magnetism, and followed by a cool but gentle northerly wind. +During these "heated terms," a general showery disposition sometimes, +though rarely, appears, with isolated showers, which bring no mitigation +of the heat. Not until a southern extension of them appears, followed by a +N. W. air, does the term change, so far as I have observed. + +By the 20th of August, in the latitude of 42 deg., an evident change of +transit is observable, by one who watches closely, although the range of +the thermometer in the day-time may not disclose it. A greater tendency to +cirrus-formation is visible. The nights grow cooler in proportion to the +days. The swallows are departing, or have departed; the blackbirds, too, +and the boblinks, with their winter jackets on, _their plumage all changed +to the same colors_, are flocking for the same purpose, and hurrying away. +The pigeons begin to appear in flocks from the north, and the first of the +blue-winged teal and black duck are seen straggling down the rivers. At +this season, and nearly coincident with the change, the peculiar annual +catarrhs return. These are colds (so called) which at some period of the +person's life were taken about or soon after the period of change, and +have returned every year, at, or near the same period. They soon become +_habitual_, and no care or precaution will prevent them. I know one +gentleman who has had this annual cold in August for twenty-seven years, +with entire regularity; and another who has had it nineteen years; and +many others for shorter periods. I never knew one which had recurred for +two or three years that could be afterward prevented, or broken up. _Very +instructive are these annual catarrhs_ to those who think health worth +preserving, and in relation to the change of transit. + +_The change is felt over the entire hemisphere._ Between the 20th of +August and the 10th of September hurricanes originate in the tropics and +pursue their curving and recurving way up over us; or long "north-easters" +commence in the interior and pass off to E. N. E. on to the Atlantic, +followed now in a more marked degree by the peculiar N. W. wind, so common +over the entire Continent in autumn and winter. + +By the 10th of September the pigeons may be seen in flocks in the morning, +and just prior to the setting in of a brisk N. W. wind, hurrying away +southward with a sagacity that we scarcely appreciate, to avoid the +anticipated rigors of winter, and to be followed soon by all the migratory +feathered tribes that remain. + +The nights grow cooler, although the sun shines hot in the day-time, and +woe to the person, unless with an iron constitution, who disregards the +change, and exposes himself or herself without additional protection, to +its influence. Nature has taken care of those who depend upon her, or upon +instinct, for protection. The feathers of birds and water-fowl are full; +the hair and the fur are grown. Beasts and birds have been preparing for +the change, and are ready when it begins. They know that the earth is +changing. The shifting machinery is fast carrying south that excess of +negative electricity which has so much to do with giving it its summer +heat. They feel its absence, even during the day, and the contrast between +that and the positively electrified northern atmosphere, which now follows +every retreating wave of condensation. + +The musk-rat builds, of long grass and weeds, his floating nest in the +pond, that he may have a place to retire to, when the rain fills it up and +drives him from his burrow in its banks. + +But man, with all his intellect, is too heedless of the change. Additional +clothing is now as necessary to him as to animals, but it is burdensome to +him in the day time, and therefore he will not wear it, how much soever it +would add to his comfort and safety during the night. He stands with his +thin summer soles upon the changed ground, or sits in a current, or in the +night air, less protected than the animals, and dysentery or fever sends +him to his long home. He has _intelligence_, but he lacks _instinct_. He +has time for the changes of dress which fashion may require, but none for +those which atmospherical changes demand. _Fashion_ has attention in +_advance_; _death_ none till _at the door_. + +Now the southern line of the extra-tropical belt of rains descends upon +those who, living between the areas of magnetic intensity, have a dry +season; and the focus of precipitation in that belt descends every where. +"_Winter no come till swamps full_," the Indians told our fathers, and +there is truth in the remark; although like other general truths +respecting the weather, it is not always so in our climate. Rains fall +during the autumnal months, as during the spring months, and while the +transit of the machinery is active and the evaporation is less. And the +magnetic comparative rest, and the seed time and equable "spell" of April +is reproduced in the Indian summer of autumn. + +The machinery gradually and irresistibly descends, and with an excess of +polar positive electricity, comes snow; Boreas controls, and winter sets +in, reaching its maximum of cold in January again. + +Remembering, then, the differences in the normal conditions of the seasons +and months, and the different characters that the winds, and storms, and +clouds, and other phenomena bear in them respectively, let us now look at +the signs of foul or fair weather not herein before fully stated, upon +which practical reliance may be placed. + +In the first place, we must look to the forming condensation. There are +many days when the atmosphere is without visible clouds, but few when it +is entirely without condensation. Such days are seen during the dry season +in the trade-wind region; and with us, in mid-summer drouths, which +partake of this tropical character; and when, at any season, but +particularly in winter, the N. W. wind in large volume has elevated the +trade very high. Condensation is not necessarily in form of visible cloud. +It may be of that smoky character which sometimes attends mid-summer +drouths, giving the sun a blood-red appearance; or it may be like that +change from deep azure to a "lighter hue," obscuring the vision, which +Humboldt describes as preceding the arrival of the inter-tropical belt of +rains. Gay-Lussac, and other aeronauts, have seen a thin cloud stratum at +the height of 20,000 to 30,000 feet, not visible at the earth, although +some degree of mistiness and obscurity were observed. At that elevation +the clouds are thin, and always white and positive. Some degree of +turbidness is frequent; it may occur, as we have stated, with N. W. wind, +but, if it does, the wind soon changes round to the southward. + +This turbidness or mistiness, where it exists, and indicates rain, does +not disappear toward night, as it should do if but the daily cloudiness +which results from ordinary diurnal magnetic activity, but becomes more +obvious at nightfall; and, when hardly visible at mid-day, or during the +afternoon, may then be observed, obscuring in a degree, the sun's rays; +and, later in the evening, forming a circle round the moon. Thus Jenner-- + + "Last night the sun went _pale to_ bed, + The moon in _halos_ hid her head." + +And so, too, Virgil-- + + "The sun, too, rising, and at that still hour, + When sinks his tranquil beauty in the main, + Will give thee tokens; certain tokens all, + Both those that morning brings, and balmy eve. + + * * * * * + + When Sol departs, his mighty day-task done, + How varied hues oft wander on his brow. + + * * * * * + + If the ruddy blaze + Be _dimm'd_ with _spots_, then all will wildly rage + With squalls and driving showers: on that fell night + None shall persuade me on the deep to urge + My perilous course, or quit the sheltering pier. + But if, when day returns, or when retires, + _Bright_ is the orb, then fear no coming rain: + Clear northern airs will fan the quiv'ring grove. + Lastly, the sun will teach th' observant eye + What vesper's hour shall bring; what clearing wind + Shall waft the clouds slow floating--what the South + Broods in his humid breast. Who dare belie + The constant sun?" + +More frequently this kind of condensation is sufficiently dense at +night-fall to take shape, and show a bank when the sun shines horizontally +through a mass of it. I am now speaking of _storm_ condensation, or that +which indicates the approach of a storm. Thunder clouds at nightfall, +dark, dense, and isolated, are, of course, to be distinguished. Those, +every one understands to indicate a shower, and immediate succeeding fair +weather. + +The halos do not, in cases of incipient storm condensation, always appear. +The moon may not be present: though, in her absence, I have seen them in +the light of the primary planets; or she may be in the eastern portion of +the heavens. When this is so, and the condensation forms slowly, there may +be less appearance of it, after the sun disappears, than before, although +a storm is approaching, and sure to be on by the middle of next day, and +perhaps with great violence. When the failure of the light no longer +reveals the denser condensation in the west, the stars may shine, as did +the sun, dimly but visibly, through the partial and invisible +condensation; and one who did not notice the bank in the west, at +nightfall and before dark, may be deceived by the seeming clearness of the +evening. Thus Virgil-- + + "Mark, with attentive eye, the rapid sun-- + The varying moon that rolls its monthly round; + So shalt thou count, not vainly, on the morn; + _So the bland aspect of the tranquil night + Will ne'er beguile thee with insidious calm_." + +All early condensation and indications derived from it, must be looked for +in the west. From that quarter all storms come. These indications at +nightfall are of a varied character. They may consist of primary +condensation in the trade, or of secondary condensation, scud running +north toward a storm, the condensation of which has not yet visibly +reached us, but which will extend south and pass over us. It may be a +heavy bank, or consist of narrow cirrus bands. Cirro-stratus cloud banks, +in the S. W., in the fall and winter, of a foggy and uniform character, +are indicative of snow. The body of the storm will pass south of us, and a +portion over us, the wind be north of east, and the snow will not be +likely to turn to rain before it reaches the earth, by reason of a +southern middle current. + +Banks in the N. W. indicate rain at all seasons. The storm is north of us, +working southerly, and such storms rain on the southern border--in winter +even--because they have the wind on that border from south of east. It +may, indeed, snow, but if so, probably in large flakes, soon turning to +rain. There are other appearances at nightfall which deserve +consideration. A red sun, with smoky air, is indicative of continued dry +weather, a frequent appearance in dry terms, lasting three or four days, +at least, from the commencement. So is a red appearance of the sky, when +there are no clouds, indicative of a fair day following. On this subject +we have an allusion to the weather, by our Saviour while on earth, which, +like all such allusions found in the Bible, is of remarkable philosophical +accuracy. It is found in Matthew, chapter xvi., verses 2 and 3: "He +answered and said unto them, When it is evening ye say, It will be fair +weather, for the sky is red. And in the morning, It will be foul weather +to-day, for the sky is red and lowering. O, ye hypocrites, ye _can +discern_ the face of the sky," etc. + +Another allusion to the weather, though not applicable to this point, I +will refer to in passing. It is found in Luke, chapter xii., verses 54 and +55: "And he said also to the people, When ye see a cloud rise out of the +west straightway ye say, There cometh a shower; and so it is. And when ye +see the south wind blow, ye say, There will be heat; and it cometh to +pass." + +This is all very true, and might have been cited to show the universality +of the phenomena. But to return. + +We have an old English proverb alluding to the same phenomena, of great +value and truth, viz.: + + "An evening red and a morning gray + Are sure signs of a fair day; + Be the evening gray and the morning red, + Put on your hat or you'll wet your head." + +The sky is red if there be no condensation at the west to obscure the rays +of the sun; if there be, it is gray, or there is a bank or cloud, and it +is obscured. So if there be no condensation over, or to the east of us, in +the morning, to reflect the rays of the sun, the sky is gray; if there be +such condensation, the sun is reflected from it, and the sky is red. Such +morning condensation is indicative of foul weather. It is, as we have +said, the eastern edge of an approaching storm, on, or under which, the +sun shines and illumines it. Thus, at night, it shines through a portion +at the west, which is situate between the sun and us, making the sky gray: +but shines on, or under, a portion in the morning, east of us, but not far +enough east to obscure the horizon, and the rays of the rising sun are +reflected from it. In either case the red or gray appearance results from +the relative situation of the sun and the eastern edge of an approaching +storm. + +The following couplet of Darwin is an apt description of the morning +appearance: + + "In fiery red the sun doth rise, + Then wades through clouds to mount the skies." + +The sun is often reflected in vivid colors, from the under surface of +clouds, at sunset. This is an indication of fair weather. It is evident +the sun shines through a _clear atmosphere beyond the cloud_, or his rays +would not reach and illume the lower surface of the cirro-stratus with +such distinctness. He "_sets clear_," as is said; the clouds are passing +off, and there are none beyond. It is this appearance, in different forms, +when there happen to be patches of broken, melting cirro-stratus above the +horizon, which makes the beautiful sunsets that attract attention. So the +sun is reflected, in beautiful colors sometimes, from the cumulus clouds +which have passed over to the east. The most beautiful and variegated I +have ever seen, were reflected from that imperfect cumulus condensation +which takes place occasionally during long drouths--doubtless resembling +that which is seen over Peru, hereinbefore alluded to, as described by +Stewart. + +It is not, then, the presence of cloud condensation at the west, at +nightfall, which alone indicates foul weather; but such condensation, +whatever its form, as evinces that it is not the _dissolving_ cloud of the +day, but the eastern, approaching portion of a _still denser portion +beyond, through, or under which, the sun can not shine clearly, but which +wholly or partially obscures it_. _Remembering this philosophy of the +matter_, the observer will soon be able to detect the various forms of +condensation which originate or exhibit themselves at nightfall, and +whether they indicate an approaching storm or not, without a more explicit +specification of them. It is an important hour for observation; "Let not +the sun go down" without attention. + +When the condensation is obvious, but thin, at nightfall, it may not, as I +have said, be discernible in the evening. But there are methods by which +the incipient storm condensation may be detected. The number of the stars +visible, and the _distinctness_ with which they may be seen, indicate the +absence or presence of condensation and its density. Virgil, alluding to +the indications of fair weather, says: + + "_Brightly_ the stars shine forth; Cynthia no more + _Glimmers_ obnoxious to her brother's rays; + Nor fleecy clouds float lightly through the sky." + +The brightness of the stars and the clear appearance of the moon show the +absence of condensation and the _dissolution_ of the fleecy clouds at the +close of the day is, as we have seen, always a fair-weather indication. + +There is much true philosophy in the allusions of Virgil to the moon. +Thus-- + + "When Luna first her scatter'd fires recalls, + If with _blunt horns_ she holds the _dusky_ air, + Seamen and swains predict th' abundant shower." + +The horns, or angles of the moon will, of course, appear distinct and +sharp or indistinct and blunt, in proportion to the amount of +condensation in the atmosphere which impedes the passage of the light. For +the same reason, when the moon is new, her entire disk is visible when the +atmosphere is very clear, by reason, as is supposed, of light reflected +from the earth to the moon and back to us. This double reflection can only +take place when the atmosphere is very clear. Hence, Virgil alludes to it, +and correctly, as an indication of continued fair weather: + + "If (mark the ominous hour!) + The clear fourth night her lucid disk define, + That day, and all that thence successive spring, + E'en to the finished month, are calm and dry." + +Probably Virgil alluded to a month of the summer trade-wind drouth which +reaches up on Southern Italy. But that appearance of the moon is +occasionally seen here, and the indication is, in degree, philosophically +true. + +It is somewhat more difficult to determine what will be the result of the +condensation seen at the west in the morning, and which is not so far +east, or of such a character, as to reflect the rays of the sun; for, +although always suspicious, it is sometimes of a foggy character, and +disappears between eight and nine o'clock. If it increases in density +after ten o'clock, or is of a dense cirro-stratus character, rain may +generally be expected. If of a decided _cirro-cumulus_ character, it is +certain to disappear. Cirro-cumulus is seen in small patches, with small, +distinct, and rounded masses, in summer, in the morning, and sometime, +during the day, after high fog has disappeared, and at other times, and is +always, when of that _distinct_ character, a fair weather indication. I +have seen it thus when the wind was blowing from the N. E., and the scud +running toward a storm passing near, but to the south of us, when those +who relied upon the existence of the wind and scud as evidences that we +were to have the desired rain, were deceived. Thus, the couplet from an +old almanac: + + "If _woolly fleeces_ strew the heavenly way, + Be sure no rain disturb the summer day." + +When this morning condensation is not high fog, and is dense and passing +east with a wavy appearance, it is very certain to rain. Jenner says: + + "The boding shepherd heaves a sigh, + _For see, a rainbow spans the sky_." + +An old almanac had the following verse: + + "A rainbow in the morning + Is the shepherd's warning; + A rainbow at night + Is the shepherd's delight." + +So the proverb was originally made; but as our ancestors were not +shepherds, and had a horror of ocean storms, it was commonly quoted, in +this country, in the following form: + + "A rainbow in the morning, + The sailors take warning," etc. + +Rainbows are not reflected from _clouds_, but falling rain, and a morning +rainbow at the west is, of course, evidence that it is _actually raining +there_, and will, in all probability, pass over us. "Thunder in the +morning, rain before night," is a common saying, and a true one. There is +a belt of showers, or showery period approaching, of unusual +intensity--for thunder showers in the morning are rare. The afternoon is +their most common period, and they are very apt to appear then, when the +morning is showery. + +Of the different forms of cirrus and cirro-stratus, which appear during +the day, and indicate approaching storms, or of cumulus indicative of +showers, it is difficult to give an intelligible description without very +many illustrations. I have many daguerreotype views, taken at different +seasons of the year, and at a time when different forms of cirrus and +cirro-stratus condensation, indicative of storms, exhibited themselves. +They differ, as I have said, and it must be remembered, very much at +_different seasons_ of the year, and in _different years_, and their +delicate shades are taken with difficulty by the artist, and reproduced +with difficulty, and only at considerable expense, by the engraver; and I +have omitted them. The time will come when a knowledge of their language +will be sought for and read--when the "countenance of the sky" will be an +object of intelligent interest to all whose business may be affected by +the weather, or who love to learn of nature. But it is not yet. This is +the age of theory and speculation. The time of actual, practical, +connected observation and prognostication, which may justify expensive +illustration, is yet to arrive. + +The reader will find in the general plates representations of several +kinds of cirri. They are delicate, always white, more or less fibrous, and +form in the upper part of the trade or the adjoining atmosphere above it. +Their character and elevation should be studied, and the observer should +be careful to distinguish which is the most elevated. Not unfrequently it +may seem, to a hasty observer, that the cirrus is below the cirro-stratus +or forming stratus. But the genuine cirrus never is. It forms near, and +above, the point of congelation, and is often composed of crystals of ice +or snow. If they fall, they melt and evaporate, when there is no storm, +before reaching the earth. Aeronauts have met with them and their crystals +when there was no fall of moisture at the surface of the earth; and the +angles of reflection exhibited by halos and other optical phenomena which +form in them, enable us to detect their crystallization and the form of +it. + +They are produced by electric changes which condense the vapor, and the +coldness of the air at that elevation freezes it at the _instant of its +condensation_. + +Congelation is crystallization, and all crystallization is electric, or +magneto-electric. The snow-flakes differ in form and size according to the +suddenness of the condensation, the amount of moisture condensed, the +polarity of the strata through which they pass, and their consequent +attraction and adhesion to each other. + +The connection of electricity with these formations of cirri has +frequently been admitted, and it is perfectly obvious that the long +fibrous bands, shooting from horizon to horizon, could not be formed by +commingling of currents any more than the perfectly isolated, distinct, +enlarging-outward cumulus hail-storm, could be so formed. Cirri form at +the line of meeting, between the trade and the upper atmosphere, and in +one or the other, or both, very much according to the season, and the +suddenness with which storms are produced. These often _induce_ a layer of +cirro-stratus or stratus at the lower line of the counter-trade, and in +the surface-atmosphere, which precipitates; and this operation is clearly +discernible, and very frequently, before gentle rains. Condensation in the +whole body of the trade is usually in the form of turbidness or mistiness, +a bank or incipient stratus, without cirri. + +It seems matter of astonishment that water should float so far condensed, +in strata where the air is so much lighter, without being precipitated. +But electric attraction and repulsion between the different strata and the +vesicles, explain it. + +In mid-winter, the cirrus forms are prevalent and most distinct. After +severe cold weather, when a storm approaches, the cirri form in long, +narrow threads, parallel to each other, extending from about W. S. W. to +E. N. E., gradually thickening and forming, or inducing, cirro-stratus and +stratus, and dropping snow. This form is called the _linear_-cirrus. The +tufted, and other fibrous forms, are seen in patches also, in great +distinctness, during these mid-winter days, when the wind gets around to +the southward, and the weather is pleasant. Such days are called +"_weather-breeders_," and their _offspring_ the patches of cirrus, which +are to extend and compose, or induce the storm, and indeed are an advance +part of it, are then never absent. A clear, moderate day, in a normal +winter, with wind from any southern point, however light, between the 1st +of January and the middle of February, without these patches of cirrus, is +very uncommon. Watch and see whether they tend to cirro-stratus, or +whether the wind gets around to the N. W. at nightfall, and they +disappear. If the former, a storm may be expected; if the latter, fair +weather. + +Thus there are three peculiarities attending the forming cirrus of +mid-winter (1st of January to 10th of February): long, fibrous, parallel +bands in the morning (linear cirrus), gradually coalescing as the day +advances, after severe cold; the comoid, curled, or tufted cirrus, in +curling bunches, called "_mares'-tails_," and the _transverse_, when the +fibers are in bands or threads, which are not parallel, but cross each +other at angles, more or less acute. The two former varieties are +represented on Figure 5, page 26, indicated by one bird, but the last form +is a very prevalent one in our atmosphere. + +Various names have been given to different forms of _cirro-stratus_. Those +represented in Figure 5, page 26, are the "_cymoid_" on the right, the +"_mottled_" on the left, below the cirro-cumulus; and the "_linear_" +below that. The form known as the "_mackerel sky_" is not represented +there. It consists of regular forms, resembling the _waves_ on the surface +of the water when the wind blows a gentle breeze. But the _wavy_ form, and +of all sizes, is very frequently assumed by cirro-stratus, which is +rapidly condensing, and turning to stratus. In the "mackerel sky," +strictly so called, the waves are small, parallel, nearly distinct and +equi-distant, and resembling the appearance of a school of mackerel, +swimming in the same direction, one above another. All _wavy_ forms of +cirro-stratus indicate a disposition to increased condensation and rain. +When the waves are very large and dense, and cross obliquely, or unite at +one end, rain is very certain to fall soon, if the line of progress of the +condensation is over the observer, and the clouds are seen in the western +or N. W. quarter of the sky. + +But there are few forms which are not occasionally seen when no rain or +snow falls. The intensity of the electric action which produces them may +not be sufficient to effect precipitation, or they may be the attendant, +attenuated _lateral_ condensation, which frequently "thins out" a +considerable distance from the dense, precipitating portions of the storm. + +If that denser portion is north of us, the probabilities of rain are +greater, for there is always a probability that the storm may be of the +character which is extended south, by a polar wave. The observer must +watch the formation of cirri, and the different forms of cirro-stratus and +stratus, and become familiar with their appearance. It is not a difficult +task. With the aid of a few general directions he will soon be familiar +with them: + +1. Get a correct idea of the different characters of the primary clouds. +The true fibrous _cirrus_--the different forms of _cirro-stratus_--the +smooth, uniform _stratus_--the _cirro-cumulus_, which is nothing but a +cirro-stratus, separated into _distinct masses_ by the repulsion of static +electricity--and the _cumulus_, too distinct ever to be mistaken. There is +no difficulty, except with the varied forms of cirro-stratus. It is +useless to attempt to give, or the observer to rely on, names for these +numerous forms, without as numerous illustrations. Those in use are rarely +applied correctly. I have never met with ten persons who applied even the +term "mackerel sky" to the same precise form of cirro-stratus. In relation +to all of them it is to be observed that polar belts of condensation, and +local appearances of considerable extent, are often too feeble in action +to precipitate, even when the mackerel form is present; and all may be the +lateral attendants of passing storms. Therefore, + +2. Satisfy yourself whether the cirrus or cirro-stratus increases in +density and tends to the formation, or induction, of stratus; and whether +it is isolated, or an extension of the condensation of a storm, and if the +latter, _where that storm is_. The time will come when an intelligent use +of the telegraph will do this for you. + +3. Look also to the character of the wind, if there be any. On this +subject I have perhaps said all that is necessary in the preceding pages. +Next to condensation, the direction and character of the wind is the most +valuable prognostic. Indeed it often tells us that a storm is approaching, +and the quarter from which it will come, and its character, before the +condensation is visible. + +4. See if there is any _secondary_ condensation or scud. These are +sometimes seen running toward a storm, when there are not distinct clouds +visible in the western horizon, at nightfall, or in the evening, as in the +instance stated in the introduction, and sometimes from the north-east, as +in cases heretofore so often stated. But the easterly scud do not often +form in winter, until after the cirrus has passed into the form of +cirro-stratus, or has induced the latter forms in the inferior portion of +the trade, or the surface atmosphere. + +The inductive effect of the primary condensation, therefore, is not +always, and especially in winter, sufficient to create the easterly +current and scud, and it is often the case that the easterly wind is not +felt, or the scud seen, in snow-storms, until the snow has begun to fall, +and the first snow will fall with a S. W. air, as I have heretofore +stated. But when the condensation has so far advanced toward stratus that +the easterly wind and scud are obvious, there is little or no doubt that +rain or snow will fall speedily. The occasional occurrence of easterly +wind and scud, without rain, however--dry north-easters, as I have termed +them--in connection with storms passing south of us, or condensation too +feeble to precipitate, should be remembered. The long, dry, +north-easterly winds of spring have been attributed to the icebergs, but +they are overlaid by feeble stratus or cirro-stratus condensation, or are +the result of attraction, by a more southern precipitation. The observer +must be careful to distinguish between the various forms of N. W. scud and +cirro-stratus, which they sometimes resemble. This he may do _from the +direction in which they move_. Cirro-stratus always moves from some point +between S. S. W. and W. S. W. to some point between N. N. E. and E. N. E. +The various forms of N. W. scud move to the S. E. The March, foggy scud, +from between W. and N. W., rarely have any cirro-stratus above them, but +rather a peculiar turbid condensation. + +The character of the primary condensation, the direction and force of the +wind, and the direction of the secondary condensation or scud, must be the +main reliance of the observer. But I must reiterate that they all differ +in different kinds of storms, in different seasons of the same year, and +the same seasons of different years; and the observer must be careful to +make due allowance for those differences. + +There are, however, divers other secondary signs, which, although not +alone to be relied upon, will aid the observer, if carefully studied, when +the character of the clouds, and the pressure of easterly or southerly +wind and scud, are not decisive. Of these, a large class are electrical. + +The smoke descends the adjoining chimney-flues, or outside of the chimney, +toward the ground. + +Thus, Darwin, as quoted by Hone: + + "The smoke from chimneys right ascends, + Then, _spreading_, back to earth it bends." + +Smoke is electrified _positively_, by the act of combustion; the earth and +the adjacent atmosphere, when storms are gathering or approaching, is +_negative_. Hence the smoke spreads, and is attracted downward by an +opposite electricity. On the other hand, it is interesting to see, at +other times, and when the difference in temperature is not material, but +the whole atmosphere is positive, with what rapidity and compactness the +smoke will ascend in a _straight and elevated column_ from the chimney, +repelled by a similar electricity. I am aware it is generally supposed the +smoke descends because the _air is lighter_. But it is a mistake. I have +seen it descend when the barometer was at 30 deg..60, or .60 above the mean. + +There is, too, a draught downward in chimneys, in such cases when there is +no smoke or fire in any of its flues. Thus Jenner says: "The soot falls +down;" whether he meant by this that there was an actual fall of soot +other than what is occasioned by the rain falling in through the chimney +top, and disturbing the soot, as sometimes happens, I do not know. It +occurs rarely, and is of very little practical importance. But every +housewife knows that chimneys, which have been used in winter, and are +full of soot, _smell_ before storms. The odor results from a downward +draught and the dampness of the air. So the smoke from one flue will +descend another, into some unused room, on such occasions. Another class +of these electrical signs are felt by those who are suffering from chronic +diseases, which have affected the nerves and made them sensitive. Thus +Jenner: + + "Old Betty's joints are on the rack." + +And Hone adds: + + "Her corns with shooting pains torment her, + And to her bed untimely send her." + +But Old Betty's rheumatism or corns are not alone in this. Those whose +bones have been broken feel it. All invalids feel it. And, indeed, all +observing healthy persons may, and do, although all are not distinctly +conscious of it. It is common for such to say, I feel sleepy, or I feel +dull, or, It _feels_ like snow, or _feels_ like rain, and thus from their +own feelings to be able to predict, not only falling weather, but its +_character_, whether snow or rain, at a time when either may occur +consistently with appearances. + +This change is a change from the positive electricity which is so +congenial to the active--"bracing" is the usual term--to negative and +damp--for this change is accompanied by condensation, as I believe all +changes from positive to negative are. Certain it is, if the atmosphere is +highly charged with negative electricity, condensation takes place; if +with positive, evaporation. Perhaps it is a change of the associated +electricity which accompanies magnetism, and not of the free atmospheric +electricity alone. Hence another phenomenon alluded to by Jenner: + + "The walls are damp, the ditches smell." + +There are localities where this dampness is very obvious. The celebrated +William Cobbett, many years since, when a farmer on Long Island, observed +and published the fact that the stones grew damp before a storm. I know of +flagging stones that usually grow damp two or three hours before rain, +especially in spring and fall, and every step taken upon them is made +visible by a corresponding increase of condensation. + +The reverse of this takes place just before the close of storms. Flagging +stones, and walls under cover, will frequently become dry before the rain +ceases. The negative electricity becomes less as the positive prevails, +although the clouds above are still dropping rain. + +In the comparatively moist, showery climate of England, these changes from +positive to negative alternate rapidly between successive showers; but +observations of electric phenomena, or of clouds, in that climate, are +not, without qualification, safe guides for us. + +So "the ditches smell," particularly in the evening before a rain, when +the immediate surface-atmosphere is charged with negative electricity, and +the _condensing moisture_ prevents the diffusion of the odors. For the +same reason the candle will not relight, and there is crackling in the +ashes or lamp. Thus, again, Virgil: + + "Maidens that nightly toil the tangled fleece + Divine the coming tempest; in the lamp + _Crackles_ the oil, the gathering wick grows dim." + +Virgil did not live in our cold climate, and knew nothing of the crackling +in the fire, or in the ashes or coals which remain after the wood is +consumed. The lamp exhibits it on a smaller scale, and perhaps he had +noticed it when in company with the maidens. But it is sometimes +noticeable even in the lamp or candle with us. A small particle of +moisture will produce it, in a marked degree, at any time. + +In winter, when the air is highly positive and cold, the candle can be +blown out, and by another puff of the breath relighted, with ease. But +when the electricity before a storm becomes negative, and partial +condensation takes place, this can not be done. This partial condensation +before storms and showers shows itself upon vessels containing cold-water, +in summer. It seems to be the received opinion, that the condensation is +evidence of a greater _quantity_ of moisture in the atmosphere. But this, +too, is a mistake, and hence the little reliance to be placed on +hygrometers. + +This partial condensation is sometimes visible. When the sun shines +clearly, at the east or west, through a _small opening_ in the clouds, the +condensing vapor is shown by the streaks of sunlight, just as the fine +particles of dust are seen in a dark room, when a few rays of sunlight are +admitted through a small aperture. This phenomenon is often observed, and +it is said of it--"It's a going to rain; _the sun is drawing water_." + +Virgil alludes to this as seen in the east in the morning, thus: + + "But when beneath the dawn _red-fingered rays_ + Through the dense band of clouds _diverging_ break, + + * * * * * + + Ill does the leaf defend the mellowing grape; + Leaps on the noisy roof the plenteous hail, + Fearfully crackling." + +It is well ascertained that storm-clouds of great intensity have polarity +in the different portions, and that in the less intense magneto-electrical +climate of England isolated showers are often of this character--the +polarity existing in rings. Showers are doubtless thus found with us. Mr. +Wise got into one of them; see his description (Theory and Practice of +Aeronautics page 240). + +I have, in another place, alluded to the upward attraction of the dust +beneath the advance condensation of a shower. Jenner alludes to it in the +following lines: + + "The whirling winds the _dust_ obeys, + And in the rapid eddy plays." + +So Virgil: + + "Light chaff and leaflets, _flitting, fill the air_, + And sportive feathers circle on the lake." + +All these are electrical. + +In England, where the action of such isolated clouds is less intense, the +different electricities in different portions of the cloud, whose opposite +and changing action produce all the phenomena, the condensation, the cold +and congelation, the currents, etc., have been accurately ascertained. We +can not get into the situation occupied by Mr. Wise. But every man may +observe these _intestine motions_ occasionally, in the advance +condensation of an isolated thunder-shower, in front of, but near the +smooth line of falling rain. They are more lateral than upward or +downward, and are often exceedingly rapid in movement. + +I have said that hail has often been found to fall from particular and +well-defined portions of a cloud, and rain from the other portions, the +hail being positive, and rain negative. An instance of very striking +character may be found in Espy's Philosophy of Storms (Introduction, page +xx.) Doubtless in all cases thunder-showers, which are isolated and +distinct, have opposite electricity in different portions, to whose active +agency all the phenomena are owing. And the return of electricity to the +earth in the rain explains the greater fertilizing effect of the latter +compared With all artificial watering. He was a true philosopher who +attempted to stimulate vegetation by electricity. + +Sounds may sometimes aid the observer in doubtful cases in foretelling the +weather. The roar of the surf, or breaking of the waves on the shore, when +great bodies of water are disturbed by a precedent storm-wind, often heard +before the wind is perceived on the land, I have already alluded to. And +thus Virgil: + + "When storms are brooding--in the _leeward gulf_ + Dash the swelled waves; the mighty mountains pour + A harsh, dull murmur; far along the beach + Rolls the deep rushing roar." + +The moaning or whistling of the wind all have noticed. It is not uncommon +to hear the expression, "The wind sounds like rain." Jenner says: + + "The _hollow_ winds begin to blow." + +And Virgil: + + "The _whispering_ grove + Betrays the gathering elemental strife." + +This whispering is the motion of the leaves; and they are often stirred by +a peculiar motion which is not that of wind. Sometimes every leaf upon a +tree may be seen _vibrating_ with an _upward and downward_ motion, when +there is not wind enough to stir a twig. This interesting phenomenon is +electrical. Trees, and all vegetables, confessedly discharge electricity, +and such discharges move the leaves, when very active. + +With us, sounds can be heard more distinctly from the east or south, +before storms, according to the character of the coming wind. Howard +mentions an instance when he heard carriages five miles off. Steamboat +paddles, rail-road cars, and other sounds, are often heard a great +distance. The distance at which the now common steam-whistle is heard, and +the direction, is not an unimportant auxiliary indication of the weather. +Howard attributes these peculiar phenomena to the "_sounding board_," made +by the _stratum of cloud_; but sounds may be heard from the north-west, +when there is no condensation, and the wind is from that quarter, and also +from the east when it is not cloudy; and in a level country the village +bells often tell the direction of the current of air just over our heads +when we do not feel it at the surface. The wind is undoubtedly moving in a +rapid, and perhaps invisible current, not far above us. If from the east +or south, it betokens rain; if from the western quarter, fair weather. + +The conduct of the different animals furnish a considerable portion of the +signs alluded to by Virgil and Jenner, and are never unimportant auxiliary +evidence of the approaching changes, whether from dry to wet, or wet to +dry. + +The observer will find, in the conduct of our birds and animals, +especially those which are not domestic, ample evidence of the truth of +the descriptions of Virgil. He denies the animals and birds foresight, but +he does not seem to have observed that the swallow leaves for the south as +soon as the _autumnal_ change begins to be felt, and in August; nor the +evident sagacity of other _migratory_ birds. They do not act from the +"_varying impulse_" produced by an actual state of things, but a knowledge +or apprehension of those which are to come. This is nothing more or less +than foresight. So foresight tends to prudence and skill, and they +exercise both, and with reference to the future. The goldfinch does not +build her nest in the hole of the tree, or in the crotch of the limb; but +_hangs it_ with _exquisite skill_ on the slender _waving, outward branch_, +where no animal, or larger bird, or any depredator, can be sustained. She +is not more timid than others; why does she invariably thus build? What +makes her "_impulses_" differ from those of other birds, and always in the +_same manner_? + +Jenner, too, has grouped, in admirably descriptive language, many of the +peculiarities exhibited by animals and birds before approaching storms, +some of which exhibit foresight, and others not. + +Perhaps the rooster, who keeps ceaseless watch over his harem, is the most +reliable weather-watcher we have. In my earlier days, when it was the +practice to keep valuable birds of the kind much longer than it now is, +and they had opportunity to become _experienced_, it was interesting to +observe how closely they watched the weather. I well remember a venerable +chanticleer, who, perched on the tree among his hens, would always +foretell the coming storm of the morrow, by sounding forth _in the +evening_, and _often_, his defiant note. Such note in the evening was +invariable evidence of foul weather. And during the night, their earlier +and more frequent crowing is often indicative of it. It is, however, in +the earlier part of the day, in doubtful cases, that no inconsiderable +reliance may be placed on their sagacity. Often, when a storm is gathering +in the forenoon, they will announce it by an almost incessant crowing. The +habits of an _experienced_, old-fashioned bird, of this kind, will well +repay attention; but I can not answer for the Shanghai and other _fancy +breeds_. + +Jenner says: + + "The leech disturbed, is newly risen + Quite to the summit of his prison." + +Few have had, or will have, opportunities to observe this, but it is +strikingly true. It is difficult to conceive how mere condensation, from +an increase of vapor in the atmosphere, should be foreseen by the leech in +his watery prison. It is obvious, I think, there is an electric change +which reaches him, as it does the whole animal creation, the once broken +bones, and the joints of Aunt Betty. Thus much of the philosophy of signs. + +_The barometer_ is a useful instrument, in connection with observations of +the other phenomena. It is especially useful to the sailor, as its +indications relative to the winds are much the most certain. But it is +not, _alone_, to be relied upon. This is well settled, although the +reasons for it have not been understood. Why it should rise sometimes +before storms, in opposition to the general rule--or fall at others +without rain--or rise occasionally during the heaviest gales, has been a +mystery, and impaired the confidence in its accuracy and usefulness even +of the class of philosophers of whom Sir George Harvey spoke, in the +sentence quoted in the introduction. But, as I have already intimated, it +is all very intelligible. + +I have said that the barometer has no fair weather standard--the mean of +30 inches at the level of the sea being an _average_ of the _fair weather_ +elevations and the _foul weather_ depressions. Its fair weather position, +it would seem, must be above the mean, therefore, and as much above as its +foul weather depressions are below. But this is not precisely true. Its +extreme fair weather range is 31 inches, and it rarely reaches that; while +its lowest storm range is down to 28, and is the most often reached of +the two. My barometer stands about 40 feet above ordinary high-water mark. +It is not a "wheel," but an open, "scale" barometer, and a perfectly good +one. Its most reliable fair weather standard is about 30-30/100 inches. It +is its _most common summer, set fair position_, but that position is often +at other and different elevations, at other periods of the year, during +fair weather. The reader must observe for his own locality, and satisfy +himself what the most common set fair position for the barometer is, at +the different periods of the year, where he resides. When he has +ascertained this, he may apply the following principles to illustrate its +exceptional action, and in judging of the future of the weather: + +1st. _As to its rise before storms._--Supposing it to have been +stationary, at or about a set fair position, _for the period_, and for one +or two or more days, a very _gradual_ and _moderate_ rise is an indication +of continued fair weather; and a _sudden_ and _considerable rise_ is +indicative of a storm. If the sudden and considerable rise occurs in the +latter part of spring, summer, or early autumn, it indicates a storm of +the _first_ or _third classes_ described in Chapter X., if in winter, a +storm of the _first class_ only. If the elevation is _very_ sudden and +considerable, the storm will probably be _severe_. The philosophy of this, +according to my present apprehension of it, is, that these storms present +an _extended easterly front_--_settle very near the earth_--and _have a +rapid progress_--thus accumulating the atmosphere somewhat, in advance of +them. + +2d. _As to its fall before storms without previous rise._--This is always +very regular before the second class of storms, or polar belts of showers +and storms. It is very fairly exemplified in the table from Reid, on page +329. The barometer, so far as I have opportunity to observe, does not rise +from a stationary position on the approach of this class of storms. At the +commencement of heated, summer, dry terms, my barometer has most +frequently ranged at about 30.30, and gradually, but slowly, fallen below +30 inches before the belt of showers arrived, and the term closed. The +fourth rule of Dalton (Meteorology, page 183) indicates a similar law in +England. It is as follows: + + "In summer, after a long continuance of fair weather, with the + barometer high, it generally falls gradually, and for one, two, or + more days, before there is much appearance of rain. If the fall be + sudden and great for the season, it will probably be followed by + thunder." + +3d. _It falls frequently and considerably without rain._--This is owing to +the fact that _all_ regular, periodic efforts at condensation do not +result in rain. The second, third, and fourth classes of storms described, +may not (as we have said) _be sufficiently active to precipitate_, +although the _series of phenomena_ (including the fall of the barometer) +may be, in other respects, perfect. Such an instance may be found in +Reid's table, on page 329, and on the 11th of the month. But the fall in +such cases is not as great, unless the wind be violent. + +4th. _It rises during considerable gales._--But these are of the kind so +often alluded to--viz., the N. W., in the northern hemisphere, and the S. +W., in the southern; and the _philosophy_ of it has been explained, and is +observable. + +With these explanations, the reader will be able to understand, and +practically apply, the barometric changes, in connection with the other +phenomena, in forming an opinion of the weather. + +_The thermometer_ is also an auxiliary. It _rises_, during the winter half +of the year, in the _advance portion of the storm_, and falls when it +passes off again; and the reverse is true, as we have seen, when its range +is very high in summer. It is, therefore, to some extent, a useful +auxiliary, although of minor importance. + +_The hygrometer_ is of less importance still. It is not in general use as +a practical guide to the changes of the weather, and does not deserve to +be. + +A question, which has been much mooted, deserves a passing notice in this +connection--viz., whether our climate has gradually become ameliorated and +milder on the eastern part of our continent, since its settlement. I have +not space left for its discussion. Humboldt (Aspects of Nature, page 103) +is of opinion that there has been no material change. He says: + + "The statements so frequently advanced, although unsupported by + measurements, that since the first European settlements in New + England, Pennsylvania, and Virginia, the destruction of many forests + on both sides of the Alleghanys, has rendered the climate more + equable--making the winters milder and the summers cooler--are now + generally discredited. No series of thermometric observations worthy + of confidence extend further back, in the United States, than + seventy-eight years. We find, from the Philadelphia observations, + that from 1771 to 1824, the mean annual heat has hardly risen 2 deg..7 + Fahrenheit--an increase that may fairly be ascribed to the extension + of the town, its greater population, and to the numerous + steam-engines. This annual increase of temperature may also be owing + to accident, for in the same period I find that there was an increase + of the mean winter temperature of 2 deg. Fahrenheit; but, with this + exception, the seasons had all become somewhat warmer. Thirty-three + years' observation, at Salem, in Massachusetts, show scarcely any + difference, the mean of each one oscillating within 1 deg. of Fahrenheit, + about the mean of the whole number; and the winters of Salem, instead + of having been rendered more mild, as conjectured, from the + eradication of the forests, have become colder, by 4 deg. Fahrenheit, + during the last thirty-three years." + +The facts hereinbefore stated show that there is nothing like a _regular_ +amelioration; that the seasons differ during the same decade, and +different decades. The cold decade, from 1811 to 1820, has not been +reproduced. But it may be, and we know not how soon. Since that period +there has certainly been a change--for even the cold period from 1835 to +1840 did not equal that from 1815 to 1820, nor indeed those of 1775 to +1780 or 1795 to 1800. But as these variations, so far as we are enabled to +judge, depend upon the varying influence of the sun's rays, and of +volcanic action, it is impossible to say that equally cold periods will +not return, during the latter half of this century. + +If the influence of the sun was constant, and volcanic action regular, two +causes would tend to modify the seasons: + +1st. The exposure of the surface to a more effective action of the solar +rays, by a removal of the forests, and by drainage. That such action would +be more effective upon a surface thus uncovered and drained, can not be +doubted. + +2d. _The movement of the area of magnetic intensity, and the magnetic +pole, to the west._--There is such a movement, and its progress can be +measured by the increase of declination on the east of it, and its +decrease on the west. And the effect of it on climate is unquestionable. +In all probability it has had an influence upon ours; and a removal of +that area and pole still further west--60 deg. or 80 deg.--would change the +location of the concentrated trade, and the Gulf Stream, and restore to +Greenland the fertility she once had, and which the Faroe Islands now +enjoy. And, on the other hand, its removal as far east of its present +position would again depopulate Greenland, and render it again +inaccessible. But I can not pursue this subject. + +Finally, assistance may be derived from the occasional, although +imperfect, accounts of the state of the weather elsewhere, which the +newspapers afford. I have been much indebted to the Associated Press of +New York for intelligence contained in their telegraphic reports. +Occasionally they have been very full and instructive. + +On this point, however, there is less of reality in the present than of +hope in the future. The time must come when the collection and +dissemination of meteorological truth, will be deemed an object of +national importance, and national duty. Population is increasing, by +immigration and propagation, in a rapidly progressive ratio. There has +been great danger that it would outrun agricultural production. A short +crop this year would have been disastrous to our prosperity--and the +danger was imminent. Every description of business, and every financial +circle, felt that fever of anxiety it was so well calculated to induce. +The importance of extended agricultural production, and the dependence of +all classes upon its success, are now in a greater measure appreciated; +and none can fail to see the value of a correct understanding of the +weather to the agriculturist, how short-sighted soever they may be, in +relation to its direct influence upon their own prosperity and happiness. + +Our country is, physically, a most favored one. The facts disclosed or +alluded to in this volume show that it is without a parallel on the face +of the globe; and our facilities for meteorological observation, and the +ascertainment and practical application of meteorological truth, are +equally pre-eminent. The great extent and unbroken surface of the eastern +portion of the continent; its excessive supply of magnetism and +atmospheric currents, and the consequent marked character of the +phenomena; the existence and prospective increase of telegraph lines over +most of its surface; the homogeneous and energetic character of a +population united, upon so large a surface, under one government; the +freedom of that government from debt, and the excess of its revenue; the +possession of a National Observatory, with a competent philosopher at its +head; and a national institution, liberally endowed, and adapted to the +collection and diffusion of practical and scientific intelligence, give +us an opportunity and a capacity for connected observation and +investigation, and an ability to profit by it, that no other nation can +boast. + +We have, too, a just national pride. Our exploring ships have penetrated +and made discoveries in both hemispheres, and our travelers have visited +successfully every clime; and thus our national interests, and +obligations, and pride, demand an organization, practical and permanent, +in relation to this subject, and the time will come when we shall have it. + +When that time comes--when the present _limited horizon_ of each of us is +_practically extended over the entire country_--and when the actual state +of the weather over every part of it is known, at the same time, to the +inhabitants of every other, and every where _read in the light of a +correct philosophy_, prognostication will be comparatively simple and +certain; and A PROGRESS will have been made, productive of an amount of +pecuniary, intellectual, and social benefit to the people, which can not +be overestimated. May it come before the shadows of the night of death +have gathered around us, that we may have a more perfect view of that +atmospheric machinery which distinguishes our planet from others, and is, +with such infinite wisdom, adapted to make it a fit habitation for man! + + +THE END. + + + + +APPENDIX. + + +Since this work was completed I have received a very valuable publication, +entitled, the "Army Meteorological Register." It is a compilation of the +observations made by the officers of the medical department of the army, +at the military Posts of the United States, from 1843 to 1854 inclusive, +prepared under the supervision of the Surgeon-general, and published by +direction of the Secretary of War. To this, there is appended a report or +general review of the prominent features of American climatology, so far +as the basis afforded by the published observation of the army medical +Bureau would warrant positive deduction, by Mr. Lorin Blodget, a +distinguished meteorologist, accompanied by temperature and rain charts, +for each of the four seasons;--exhibiting the various local differences +and peculiarities relative to temperature and precipitation in each. + +These local differences and peculiarities and contrasts are deduced and +delineated by Mr. Blodget with much ability. He was fettered, however, by +the prevailing calorific theories, and the unfortunate practice of +grouping the phenomena into means for the seasons, Spring, Summer, Autumn, +and Winter, which grouping is arbitrary, and comparatively uninstructive. +Hence, he failed to discover what the tables and summaries most clearly +disclose--the principles and system unfolded in the foregoing work. + +But the summaries of this register contain observations made at posts in +Western and Southwestern Texas, in Kansas and Nebraska, and in New Mexico +and California, where there has been a dearth of such observations +hitherto, and enable me to demonstrate, more conclusively, and I think so +that none can fail to understand it, the truth of the philosophy I have +endeavored to exhibit. + +To do this, I will take a _year_,--divide it into two seasons, the periods +of northern and southern transit, the only natural and correct +division--and note the phenomena in each, as each progresses. + +And I will take the year 1854, because that is the last year for which the +record of observation is complete; because it had marked peculiarities +which are remembered; and because I have alluded to those peculiarities, +and those allusions should be confirmed or disproved by the record. Unless +I mistake exceedingly, the confirmation will be found signal and +convincing. + +I have assumed, pp. 187, 351, that the transits were greater in some +seasons than others; that the drought of 1854 was owing to an extreme +northern transit, or to an extension west of the concentrated +counter-trade, or both, leaving us less supplied with moisture than +usual. + +In point of fact, it appears from these observations that it resulted from +_both_ causes, operating _connectedly_; and the annals of Science rarely +furnish a more striking instance of analogical inference proved true by +subsequent investigation. + +Commencing then with the commencement of the northern transit about the +1st of February, we are enabled to trace the then location of our +concentrated trade, and its subsequent progress to the north till August, +and its influence upon temperature and precipitation. And we can also +trace the situation during the same period, of the intervening drought, +and the inter-tropical belt of rains, and the extension of the latter +north over Florida and the cotton-planting States. + +On the 1st of February, 1854, our counter-trade was somewhat more +concentrated on its extreme winter curve, over the Southern States, than +usual. Its line of excess reached up from Fort Brooke, on the peninsula of +Florida, to the northwest, a little east of Pensacola on the gulf, cutting +Mount Vernon Arsenal north of Pensacola, and extending thence +north-westwardly on to Eastern Louisiana, and curving thence and passing +N. E. or E. N. E., to the Atlantic, about the waters of the Chesapeake +Bay. It thinned out to the west over New Orleans and Baton Rouge, +supplying them moderately, but did not extend to the forts of Texas on the +west, nor the posts in the Indian Territory at the N. W. It was east of +Fort Towson, which is the south-eastern one. It did not reach St. Louis on +the north, nor extend north of the Ohio River, as will appear from the +tables hereinafter given. The following cut shows substantially its +situation on the 1st of February. + + +[Illustration] + + +Now, during the month of January, we find the following state of things. +_Under_ this concentrated trade, the temperature was above the mean, even +if Forts Monroe and McHenry on the Atlantic are included; but Mr. Blodget +discredits their returns, and some others which do not conform to general +results. On the west and north of its curving line, both precipitation and +temperature were below the mean. + +Under the counter trade, we have the following stations, with their actual +and mean temperature. I have inserted the temperature for several +subsequent months, to show a depression in April. + + +TABLE I. + + ------------------------------------------------------------------------- + | LAT. | LON. | JAN. | FEB. | MAR. | APRIL.| MAY. | + ------------------------------------------------------------------------| + Fort Moultrie | 32.45 | 79.51 | 50.83 | 53.09 | 62.72 | 62.76 | 73.35 | + Mean of 28 yrs.| | | 50.36 | 52.41 | 58.68 | 65.44 | 73.42 | + Fort Pierce | 27.30 | 80.20 | 67.91 | 67.33 | 73.01 | 71.10 | 78.41 | + Mean of 5 yrs. | | | 62.75 | 64.42 | 69.77 | 73.63 | 76.92 | + Fort Meade | 28.01 | 82.00 | 63.75 | 63.33 | 70.64 | 68.10 | 76.31 | + Mean of 3 yrs. | | | 58.40 | 63.23 | 69.02 | 69.89 | 76.69 | + Fort Brooke | 28.00 | 82.28 | 62.94 | 62.36 | 70.06 | 70.07 | 77.49 | + Mean of 25 yrs.| | | 61.53 | 63.54 | 67.72 | 71.82 | 76.64 | + Fort Myers | 26.38 | 82.00 | 67.56 | 67.39 | 73.74 | 71.07 | 79.13 | + Mean of 4 yrs. | | | 63.39 | 67.98 | 72.19 | 73.86 | 80.13 | + Key West | 24.32 | 81.48 | 71.75 | 71.95 | 76.56 | 73.89 | 80.84 | + Mean of 14 yrs.| | | 66.68 | 68.88 | 72.88 | 75.38 | 79.10 | + Fort Barrancas | 30.18 | 87.27 | 54.71 | 54.56 | 64.98 | 62.93 | 75.40 | + Mean of 17 yrs.| | | 53.61 | 55.58 | 61.80 | 68.51 | 75.45 | + Mt. Vernon Ars'l| 31.12 | 88.02 | 51.52 | 53.18 | 65.24 | 62.30 | 74.64 | + Mean of 14 yrs.| | | 50.44 | 53.69 | 60.26 | 66.87 | 73.92 | + Baton Rouge | 30.26 | 91.18 | 53.43 | 56.48 | 66.24 | 64.63 | 75.10 | + Mean of 24 yrs.| | | 53.47 | 55.02 | 61.93 | 69.30 | 75.60 | + ------------------------------------------------------------------------- + + ------------- + JUNE. | JULY. + ------------- + 78.55 | 82.06 + 79.01 | 81.72 + 82.09 | 84.16 + 79.02 | 82.50 + 79.10 | 80.17 + 78.24 | 79.76 + 80.51 | 81.08 + 79.46 | 80.72 + 82.35 | 81.91 + 81.25 | 82.87 + 83.34 | 83.30 + 81.63 | 83.00 + 81.00 | 84.55 + 80.80 | 82.26 + 79.17 | 78.90 + 78.03 | 78.62 + 80.61 | 80.09 + 80.56 | 81.81 + ------------- + +It will be seen that the temperature was above the mean in January at +every post except Baton Rouge, and there it was at the mean. We shall see +hereafter that Baton Rouge was near its western line. + +Under this trade during this month, and at the same posts, the fall of +rain was as follows, compared with the mean:-- + + +TABLE II. + + -------------------------------------------------------------- + | JANUARY. | FEBR'Y. | MARCH. | + -------------------------------------------------------------- + | 1854. | Mean.| 1854. | Mean.| 1854.| Mean.| + -------------------------------------------------------------- + Key West. | 1.77 | 2.86 | 2.55 | 1.38 | 0.51 | 4.21 | + Fort Myers. | 1.15 | 3.90 | 4.70 | 2.16 | 0.20 | 4.60 | + " Brooke. | 3.88 | 2.20 | 6.89 | 3.01 | 2.44 | 3.37 | + " Mead. | 1.30 | 1.07 | 2.21 | 1.01 | 1.85 | 1.64 | + " Pierce. | 3.55 | 4.45 | 3.40 | 2.72 | 1.05 | 3.01 | + " Barrancas. | 3.45 | 3.87 | 5.55 | 4.95 | 7.21 | 5.87 | + Mt. Vernon Ars'l | 11.01 | 6.80 | 12.83 | 6.04 | 6.22 | 4.59 | + Baton Rouge. | 2.85 | 5.26 | 5.50 | 4.91 | 6.15 | 4.68 | + Fort Moultrie. | 3.80 | 2.39 | 2.84 | 2.33 | 0.25 | 4.06 | + -------------------------------------------------------------- + + ------------------------------------------- + | APRIL. | MAY. | JUNE.| JULY. + | 1854.| Mean.| 1854. | Mean.| | + ------------------------------------------- + | 2.99 | 1.55 | 3.14 | 2.58 | 4.54 | 3.45 + | 2.75 | 3.14 | 5.65 | 3.33 | 6.75 | 9.70 + | 8.82 | 1.95 | 6.21 | 3.24 | 9.44 | 15.53 + | 3.19 | 1.78 | 10.51 | 5.34 | 7.24 | 8.55 + | 7.00 | 3.85 | 5.70 | 4.27 | 6.63 | 4.97 + | 0.50 | 2.94 | 3.47 | 4.05 | 3.39 | 5.43 + | 1.96 | 4.21 | 4.45 | 4.62 | 6.72 | 6.13 + | 3.58 | 5.22 | 8.05 | 5.18 | 4.00 | 6.55 + | 2.20 | 1.75 | 3.70 | 4.08 | 4.20 | 5.69 + ------------------------------------------- + +It will be observed that in February the counter-trade and extra-tropical +belt had moved up from Key West, and a drought, which sometimes intervenes +between the concentrated counter-trade and the inter-tropical belt, +appeared there in February and March. In April, the inter-tropical belt +appeared at that point, and went on increasing till September. As the +counter-trade commenced moving north in February, an increased +precipitation above the mean commenced at all the more southern stations +under the concentrated-trade--an earnest of that irregularity which +followed, and marked the season as the most excessive of the century. + +In March, the intervening drought appeared at the other posts on the +peninsula, and also at Fort Moultrie, followed _much more closely than +usual_, by the inter-tropical belt of rains. In April, the drought +appeared at Fort Barrancas and Mount Vernon Arsenal (the wave of +precipitation having moved to the west), and slightly in comparison at +Baton Rouge. + +If now we look at the condition of things, _west_ and _north_ of the +curving line of concentrated trade, from Fort Brown, at the mouth of the +Rio Grande, in South-western Texas, through that State, the Indian +Territory, Arkansas, Missouri, Kentucky, and Northern Pennsylvania, to the +Atlantic, we find the thermometer every where in January below the mean. +The following table will show this, and the precipitation for that month +and February:-- + + +TABLE III. + + ------------------------------------------------------------------------ + | JANUARY. | FEBRUARY. | MARCH. | + |-----------------------------------------------| + | 1854. | Mean. | 1854. | Mean. | 1854. | Mean. | + -----------------------------------------------------------------------| + _Western Texas._ | | | | | | | + Fort Brown | 59.34 | 60.41 | 62.45 | 63.63 | 71.87 | 68.95 | + " Ewell | 50.47 | 52.92 | 58.12 | 57.61 | 70.34 | 67.00 | + " Inge | 47.24 | 49.46 | 56.04 | 55.39 | 67.54 | 62.63 | + | | | | | | | + _Indian Territory._ | | | | | | | + Fort Towson. | 36.32 | 43.14 | 49.29 | 45.97 | 59.55 | 53.40 | + Forts Gibson, Washita, | | | | | | | + and Arbuckle, in much| | | | | | | + the same proportions.| | | | | | | + | | | | | | | + _Arkansas._ | | | | | | | + Fort Smith. | 33.92 | 40.18 | 47.01 | 43.89 | 57.01 | 51.58 | + | | | | | | | + _Missouri._ | | | | | | | + St. Louis Arsenal. | 25.47 | 31.44 | 36.66 | 33.43 | 46.10 | 42.30 | + | | | | | | | + _Kentucky._ | | | | | | | + Newport Barracks. | 31.75 | 34.04 | 39.60 | 36.94 | 46.74 | 45.46 | + | | | | | | | + _Pennsylvania._ | | | | | | | + Allegheny Arsenal. | 29.08 | 29.25 | 33.49 | 31.16 | 40.36 | 39.02 | + | | | | | | | + _Delaware._ | | | | | | | + Fort Delaware | 32.38 | 33.67 | 34.56 | 35.84 | 43.18 | 42.90 | + | | | | | | | + _New York Harbor._ | | | | | | | + Fort Columbus. | 28.71 | 30.18 | 28.17 | 30.44 | 36.17 | 38.28 | + ------------------------------------------------------------------------ + + -------------------------------------- + | Rain in January. | Rain in February. + -------------------------------------- + | 0.45 | 1.50 + | 0.22 | 2.86 + | 0.20 | 2.15 + | | + | 1.01 | 2.00 + | | + | 1.37 | 2.05 + | | + | 0.65 | 2.40 + | | + | 3.20 | 5.30 + | | + | 2.23 | 2.33 + | | + | 2.30 | 5.45 + | | + | 2.60 | 4.00 + -------------------------------------- + +We find, also, from this and table first, that every where, except at Fort +Brown, and upon the Atlantic coast, the temperature had risen above the +mean in February. + +The situation of the belt which supplied the western coast in winter, and +its excess of precipitation, are also represented upon the cut. The +intervening area was not without counter-trade and precipitation--the +latter, of course, greatest over the area of intensity--but they were +_comparatively_ less, as the tables will show. + +The following cut and table show the situation of the concentrated +counter-trade in March. + + +[Illustration] + + +TABLE IV. + + ------------------------------------------------------------------------ + | JAN.|FEBR.| MAR.| APR.| MAY.|JUNE.|JULY. + ------------------------------------------------------------------------ + Fort Barrancas, Pensacola Bay| 3.45| 5.55| 7.21| 0.50| 3.47| 3.39| 5.43 + Mean. | 3.87| 4.95| 5.87| 2.94| 4.05| 4.66| 6.80 + Baton Rouge, Louisiana | 2.85| 5.50| 6.15| 3.58| 8.05| 4.00| 6.55 + Mean. | 5.26| 4.91| 4.68| 5.22| 5.18| 5.52| 7.42 + Fort Towson, Indian Territory| 1.01| 2.00| 5.10| 2.22|Recr'd stops here. + Mean. | 3.13| 2.97| 4.38| 5.33| | | + Fort Gibson, Indian Territory| 0.30| 1.43| 7.83| 3.16| 7.67| 2.80| 0.21 + Mean. | 1.33| 2.26| 2.54| 4.19| 4.65| 4.30| 2.75 + Fort Smith, Arkansas | 1.37| 2.05| 7.05| 6.55| 6.25| 2.26| 1.02 + Mean. | 1.96| 2.17| 2.92| 5.10| 4.46| 4.74| 3.82 + St. Louis Arsenal | 0.65| 2.40| 7.10| 4.30| 4.65| 2.20| 1.70 + Mean. | 1.93| 3.37| 3.82| 4.16| 4.88| 6.94| 0.04 + Newport Barracks, Kentucky | 3.20| 5.30| 8.10| 2.10| | | + (No Mean given.) | | | | | | | + ------------------------------------------------------------------------ + +We see from this table that its focus had extended west in Florida over +Fort Barrancas, and over Baton Rouge in Louisiana; N. W. to Forts Towson +and Gibson in the Indian Territory, and Smith in Arkansas; north to St. +Louis Arsenal at St. Louis, and to Newport barracks in Kentucky; but it +was spread over a larger surface east of the mountains. Its greatest +progress for the month, was a west and north-west progress. + +In April, we find it had progressed rapidly west and north-west, and its +position is shown by the following cut and table. + + +[Illustration] + + +TABLE V. + + ------------------------------------------------------------------------ + | JAN.|FEBR.| MAR.| APR.| MAY.|JUNE.|JULY. + ------------------------------------------------------------------------ + Fort Riley, Kansas. | 0.00| 0.94| 1.86| 4.55| 4.35| 1.10| 0.00 + Fort Leavenworth, Kansas. | 0.04| 1.78| 1.33| 3.35| 5.55| 4.50| 0.18 + Mean | 0.72| 1.01| 1.61| 2.74| 3.62| 5.80| 3.15 + Alleghany Arsenal, Pittsburgh | 2.23| 2.33| 2.82| 4.21| 2.24| 2.06| 1.45 + Mean | 2.18| 2.17| 2.70| 3.10| 3.58| 3.56| 2.97 + Fort Columbus, New York Harbor| 2.60| 4.00| 0.70| 8.80| 7.70| 2.20| 1.90 + Mean | 2.78| 2.92| 3.44| 3.33| 4.78| 3.46| 3.17 + Fort Independence, Boston | 2.50| 3.36| 2.55| 5.40| 4.28| 2.00| + West Point. | 3.52| 5.04| 2.81|10.53| 2.00| 1.62| + Mean | 3.50| 3.44| 3.71| 4.55| 6.18| 4.79| + ---------------------------------------------------------------------- + +We see, too, that both east and west of the mountains, its focus of +precipitation was one month in advance of the mean. At all the stations +where the greatest fall was in March, it should have been in April, and +the fall at those points was greatly in excess of the usual quantity. And +the same was true of stations reached in April. The concentrated trade, +instead of spreading out, and precipitating over the whole south-eastern +portion of the continent (its normal condition), was gathered into a wave +of greater volume, resulting in greater precipitation, and was rapidly +hastening its curve to the west over Texas, and to the north-west over the +Indian Territory, and northward on its usual curve to the north and east +of them. + +The observations for April disclose another singular and instructive +condition. The temperature, that had every where been above the mean in +March, fell below it in April under the concentrated trade. And snow fell +on three days in some localities, and four in others. + +Along the Ohio River, it fell to the depth of 8 to 10 inches on the 17th, +and east of the mountains to a greater depth on the 18th, one day later. +It fell to the depth of 4 inches at Marietta on the 29th also. Dr. +Hilldreth, American Journal of Science for March, 1855, says:-- + +"It is a singular fact that the deepest snow, 8 inches, fell on the 17th +of April, and at the head waters about Pittsburg over a foot. Also, on the +29th of the month, at Marietta, 4 inches, a very rare occurrence." This +depression of the temperature was quite general, but the fall of snow was +local. The latter was north of a line drawn from Fort Laramie, at the base +of the Rocky Mountains, in an E. S. E. direction--north of Forts Kearney +and Leavenworth, and of St. Louis, but south of Newport barracks in +Kentucky, and from thence to the Atlantic. Snow fell at every station +north of this line, at no station south of it. The depression of +temperature, however, was experienced over the continent, east of the +Rocky Mountains, under, and south of, the belt of precipitation. Now what +occasioned this general depression of temperature, and local fall of snow? +It will not do to say, as perhaps some calorific theorist may be inclined +to say, because the concentrated trade had been carried up where it was +cold, a month too soon; or that the sun had heated the land in advance of +it, and drawn it up. + +For, 1st, it might be asked how, if it was warm enough to draw it up, +could it be cold enough to make it snow; or, 2d, how happened it to start, +when, as we have seen, it was warmer than the mean under it, and colder +than the mean to the north and west of it, when it commenced its journey? + +But again, it snowed at posts north of the line, while the thermometer +remained above the mean; and the thermometer fell below the mean down to +Fort Brown in south-western Texas, and at Key West in the southern part of +Florida; and what is more remarkable still, at Key West, Fort Barrancas, +and every other south-eastern station, except Forts Brooke and Moultrie, +it not only fell below the _mean_ of the month, but _below the actual +temperature of March_. (See Table I.) At Forts Brooke and Moultrie it did +not rise above that temperature. West of the Rocky Mountains the +depression was not felt; nor at stations north, or north-west of the belt +of precipitation. + +It is obvious, the calorific theory can furnish no rational explanation of +this matter; for the reason that, whatever the cause, it operated not +only under, but south, and far south of the belt of precipitation. It +could not have been spots upon the sun, or other general cause, for then +it would have operated in New Mexico and California, and at the +north-western stations. It operated most intensely in Florida and the +South-Eastern States, which approach most nearly the volcanic areas of +South America and the West Indies. I believe it to have been occasioned by +volcanic action affecting the local magnetism of our intense area; but it +is a most important development, and should be thoroughly investigated. We +may find in it the key to the mysterious, but unquestionable, influence of +volcanic upon magnetic action; and I hope the distinguished +surgeon-general will cause the records of that month to be published "in +extenso." + +In May and June, the trade became more concentrated, a perfectly developed +belt from the Rio Grande to the Lakes and British possessions, and +doubtless to the Atlantic, with every where a central focus of excessive +precipitation, gathering to itself in one vast wave the current that +should have been spread out over the whole country; and leaving every +where on its eastern and southern borders, down to the northern edge of +the inter-tropical belt of rains--(which extended up to lines drawn from +Baton Rouge to Charleston)--a _perfectly well developed_ and _defined +drought_. That drought will long be remembered. The following cuts show, +approximately, the location of the belt of precipitation and drought for +those months, and the table which follows will show their correctness. + +The tables also show that this wave was occasionally a double, or divided +one--evinced by an intervening _partial_ precipitation. Tables IV., V., +and VI., also show the commencement of the drought at the several +stations, as the wave moved to the west and north. + + +[Illustration: MAY.] + + +[Illustration] + + +TABLE VI. + + JAN. FEBR. MAR. APR. MAY. JUNE. JULY. AUG. SEPT. + Fort Brown 0.45 1.50 1.15 0.05 4.10 7.65 4.25 5.00 11.31 + Mean 1.61 2.25 1.20 0.56 2.21 4.55 1.95 2.76 6.73 + Ringgold Barracks 0.70 1.69 0.22 0.00 2.83 10.98 4.06 1.58 3.02 + Mean 1.24 1.18 0.72 1.08 2.09 3.47 3.18 1.50 3.22 + Fort Merrill 0.11 1.99 0.05 1.16 7.66 4.70 5.44 3.13 5.01 + Mean 0.23 2.09 0.09 1.62 3.43 4.10 6.13 3.40 4.60 + Fort Duncan 0.05 0.69 1.50 0.00 2.53 6.83 0.83 0.90 4.81 + Mean 0.26 1.27 1.34 0.71 1.50 5.63 3.35 0.93 3.28 + Fort Inge 0.20 2.15 3.00 0.75 3.88 2.09 0.97 1.67 4.80 + Mean 0.64 2.21 1.79 1.26 3.01 5.38 3.66 2.02 2.21 + Fort McKavet 0.01 0.77 2.10 0.28 3.72 0.15 2.91 0.04 3.86 + " Belknap 0.11 1.10 1.42 1.75 4.97 8.33 0.00 0.75 1.53 + " Massachusetts, + Northern New + Mexico 3.93 0.24 2.14 2.61 1.53 + Fort Kearney 0.23 1.33 1.87 2.56 4.15 5.40 3.51 1.18 4.60 + Mean 0.50 0.48 1.55 2.68 6.57 4.36 5.07 2.62 1.83 + Fort Laramie 0.18 0.40 0.80 3.98 4.46 3.67 3.26 1.27 1.60 + Mean 0.27 0.71 1.37 1.93 5.39 2.95 1.83 0.92 1.33 + Fort Ridgley 1.20 0.01 1.18 2.83 6.84 2.70 2.49 2.28 2.58 + " Snelling 0.72 0.03 1.03 2.51 4.30 3.31 3.92 1.75 6.55 + Mean 0.73 0.52 1.30 2.14 3.17 3.63 4.11 3.18 3.32 + Fort Ripley 0.67 0.03 0.79 0.97 4.34 3.68 0.62 1.69 4.40 + Mean 0.86 0.37 1.80 1.42 3.09 5.15 5.20 2.27 4.92 + Fort Mackinac 2.59 1.23 1.56 1.04 2.65 6.35 5.67 4.26 3.22 + Mean 1.25 0.82 1.14 1.21 2.32 2.81 3.20 2.87 2.97 + Fort Brady 2.49 1.18 1.34 2.14 3.61 1.23 3.21 3.86 3.18 + Mean 1.84 1.13 1.37 1.83 2.24 2.83 3.73 3.39 4.33 + Fort Niagara 1.63 2.52 1.87 2.25 3.90 1.71 4.08 1.52 2.61 + Mean 2.25 1.89 2.12 2.20 2.55 3.28 3.49 3.04 3.95 + +But the belt of trade continued its progress to the west and north, and +during the months of July and August the drought extended in both +directions, reaching, in August, from Mississippi, Alabama, Georgia, and +South Carolina, to the Lakes, and from the Rocky Mountains to the +Atlantic. Its position is shown by the following cut, and the position of +the belt of precipitation by the following table. + +[Illustration] + + TABLE VII. + + _Situation of the focus of Precipitation in July and August._ + + ----------------------------------------------------------- + | JUNE.| JULY.| AUG. | SEPT.| OCT. + ----------------------------------------------------------- + _New Mexico._ | | | | | + | | | | | + Fort Thorne | 0.08 | 2.23 | 6.01 | 3.50 | 0.00 + Albuquerque | 0.28 | 2.50 | 1.19 | 2.67 | 1.37 + Santa Fe | 0.32 | 4.11 | 3.86 | 4.06 | 2.50 + Fort Defiance | 1.24 | 3.94 | 5.24 | 3.47 | 0.62 + " Yuma | 0.00 | 0.01 | 2.37 | 0.17 | 0.30 + San Diego | 0.02 | 0.07 | 1.35 | 0.13 | 0.01 + Fort Snelling, Minnesota | 3.31 | 3.92 | 1.75 | 6.35 | 1.23 + " Brady | 1.23 | 3.21 | 3.86 | 3.18 | 3.40 + " Mackinac | 6.35 | 5.67 | 4.26 | 3.22 | 2.28 + ----------------------------------------------------------- + +I have not space for all the comment which this exposition is calculated +to induce. The reader will not only find in it an explanation of the +extraordinary character of the summer of 1854, but will see from the +_means_, that it was but an _excessive development_ of an ANNUAL +PHENOMENON,--THE PROGRESS OF A CONCENTRATED COUNTER-TRADE. + +It is not necessary to follow with particularity the return transit. It +required no great degree of sagacity to predict, at the time, that the +drought would continue in the vicinity of New York till about the 10th of +September. The return of the belt to that latitude, was not to be expected +before that time, and the drought continued, in fact, until the 9th of +September. + +Its return progress was slow, and it was every where behind time. The +autumn was warm, and so, indeed, were December and January, west of the +area of magnetic intensity, although upon, and east of it, there was a +depression in December. The retreating but lingering edge of +counter-trade, with its excess of snow for the season, caught the Iron +Horse, with its train and passengers, upon the prairies of the west, and +laid its embargoing hands upon them. Few, if any, can have forgotten the +thrilling accounts which reached us from that section, of the sufferings +endured by those who were thus embargoed for days and nights, far from the +comfortable habitations of their fellow men. + +But the return transit, though slow, was extreme, and February and March +were exceedingly cold for the season. The transit to the north, again, did +not commence as early as usual, and the spring was backward, and the +summer cool. Both were without irregularity, and the season was +productive. The following table exhibits the temperature on a line of +posts, running north and south at the west, during the winter months of +1855, and will illustrate what has been said. + +TABLE VIII. + + --------------------------------------------------- + 1855. |JANUARY |FEBRUARY.| MARCH.| APRIL. + --------------------------------------------------- + Key West | 67.18 | 65.94 | 70.28 | 75.09 + Mean | 66.58 | 68.88 | 72.88 | 75.38 + Fort Snelling | 17.09 | 12.62 | 25.30 | 49.86 + Mean | 13.76 | 17.57 | 31.41 | 46.34 + Fort Kearney | 23.55 | 25.69 | 32.86 | 54.39 + Mean | 21.14 | 26.11 | 34.50 | 47.13 + Fort Laramie | 35.85 | 29.01 | 36.41 | 52.94 + Mean | 31.03 | 32.60 | 36.81 | 47.60 + Fort Arbuckle | 41.94 | 39.86 | 49.09 | 67.43 + Mean | 39.10 | 43.69 | 53.22 | 61.85 + Fort Belknap | 45.92 | 44.49 | 53.09 | 70.00 + Mean | 42.80 | 47.47 | 56.90 | 65.79 + Fort Chadbourne | 48.89 | 45.87 | 56.68 | 68.51 + Mean | 44.29 | 46.75 | 58.01 | 65.52 + Fort McKavitt | 46.74 | 44.51 | 53.66 | 67.05 + Mean | 44.75 | 46.87 | 57.39 | 66.25 + Fort Merrill | 54.51 | 54.65 | 61.82 | 74.50 + Mean | 54.82 | 57.20 | 68.66 | 73.27 + Fort Brown | 60.23 | 61.60 | 66.24 | 74.98 + Mean | 60.41 | 63.63 | 68.95 | 75.05 + Fort Inge | 52.21 | 50.63 | 61.22 | 74.48 + Mean | 49.46 | 55.39 | 62.63 | 68.02 + --------------------------------------------------- + +The return transit to the south for this winter, 1855-6, has been an +extreme one. It is too early yet (Feb. 18th) to write its history, but the +extreme southern transit is as obvious as the unusual severity of the +cold. The rains which usually fall upon the Southern States are +precipitated further south upon the West Indies, and threaten a +deterioration of their sugar crop. The snow, and cold winds, and ice, of +the middle latitudes, are felt even in Florida. Our sheet of +counter-trade has been exceedingly thin, and the barometer has ranged, in +fair weather, much below the mean. Occasional, and for a part of the time, +_weekly_ periods of an increase of its volume, with a corresponding +elevation of the barometer, and a consequent moderation of the intense +cold, and a storm, have occurred. But those periods have been few and +brief. No regular thaw has yet occurred. From the 26th of December to this +date, at Norwalk, there have been but two periods when the wind has blown +from the south-west with sufficient force to stir the limbs of the trees. +There has been no wind from south of that point, or east of north-east; +and even our storm-winds, with one exception, have been north of +north-east--owing to the situation of the focus of precipitation far to +the south of us--and there is reason to fear that a cold summer like those +of 1816 and 1836 may follow. If this extreme transit is owing to defect in +the influence of the sun, from spots, or other causes, such will probably +be the result. If from volcanic action at the south, the influence of that +action may cease, and a rapid return transit, and an ordinary season, may +follow. Believing in the laws of periodicity in relation to the weather +and disease, I planted an early kind of corn (the Dutton), in 1836, and +had a crop when few around me succeeded. We must watch this return +transit, with hope, indeed, but not without fear, and be wise in time. + +There is a mass of other evidence in these summaries which shows the truth +of what I have written. There is not a deduction of Mr. Blodget which it +will not explain. The ascent of the summer lines of temperature to the +west is explained by the diminution of magnetic intensity. Their descent +in winter by the location and attractions of the concentrated trade. The +excess of precipitation in Alabama and Mississippi by the succession of +summer and winter belts. That of the interior of the Atlantic slope in +summer, by the showers which fall upon the elevations; and of the coast, +by the easterly storms and their attraction of the surface atmosphere of +the ocean, at other seasons. But I cannot further particularize. Even the +influence of the spots is clearly demonstrated by the observations at +_interior stations_, which were unaffected by contiguous oceans or +elevations. At Forts Washita, Gibson, Scott, Smith, and others, the years +1847 and 1848 were below the mean. All that evidence, and those +deductions, however, I must pass by for want of space, and take leave of +the subject. + + + + +Footnotes: + +[1] See the diagram for summer at page 55. + +[2] Law of Storms, p. 42. + +[3] Kearakakua Bay (called Cavrico above), is on the S. W. side of the +island, and the trade was reversed during the day by the cloud +condensation inland. + +[4] Lieutenant Wilkes spent twenty days upon the top of this or an +adjoining mountain, and his observations there will be alluded to in +another connection. + +[5] All attempts to produce this result by the sudden exhaustion of air +about the chickens in receivers, or shooting them from cannons, have +failed, and no patent for a chicken-picker has been applied for. + +[6] A meter is 1 yard, and .0936 of a yard. + +[7] See his map, accompanying the Geography of the Sea. + +[8] See Am. Jour. of Science, New Series, Vol. 18. p. 187. + +[9] Their estimate was 100 to 120 miles. + +[10] Since the text was in type, and, as might have been anticipated, we +have intelligence confirmatory of this, from the Cape De Verde Islands. +The inter-tropical belt of rains has not moved as far north as the +northern islands--they have had no rain--and the people are in a starving +condition. + + + + +Transcriber's Notes: + +Passages in italics are indicated by _italics_. + +Punctuation has been corrected without note. + +The following misprints have been corrected: + "appearnces" corrected to "appearances" (page 44) + "Faroday's" corrected to "Faraday's" (page 84) + "gentleman" corrected to "gentlemen" (page 96) + "two" corrected to "too" (page 105) + "surise" corrected to "sunrise" (page 111) + "acion" corrected to "action" (page 164) + "Stanta corrected to "Santa" (page 167) + "Augugst" corrected to "August" (page 167) + "baloon's" corrected to "balloon's" (page 192) + "mannner" corrected to "manner" (page 214) + "1198" corrected to "1798" (page 221) + "sevententh" corrected to "seventeenth" (page 240) + "maner" corrected to "manner" (page 254) + "particulary" corrected to "particularly" (page 256) + "are are" corrected to "are" (page 288) + "iso-theral" corrected to "iso-thermal" (page 299) + "the the" corrected to "the" (page 360) + "phenonema" corrected to "phenomena" (page 403) + "calorifice" corrected to "calorific" (page 409) + +Other than the corrections listed above, inconsistencies in spelling and +hyphenation have been retained from the original. + +Tables throughout this text version have been adjusted for readability. + + + + + + +End of the Project Gutenberg EBook of The Philosophy of the Weather, by +Thomas Belden Butler + +*** END OF THIS PROJECT GUTENBERG EBOOK THE PHILOSOPHY OF THE WEATHER *** + +***** This file should be named 33429.txt or 33429.zip ***** +This and all associated files of various formats will be found in: + http://www.gutenberg.org/3/3/4/2/33429/ + +Produced by Robin Monks and the Online Distributed +Proofreading Team at http://www.pgdp.net (This book was +produced from scanned images of public domain material +from the Google Print project and from The Internet Archive: +American Libraries.) + + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. 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