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diff --git a/.gitattributes b/.gitattributes new file mode 100644 index 0000000..d7b82bc --- /dev/null +++ b/.gitattributes @@ -0,0 +1,4 @@ +*.txt text eol=lf +*.htm text eol=lf +*.html text eol=lf +*.md text eol=lf diff --git a/LICENSE.txt b/LICENSE.txt new file mode 100644 index 0000000..6312041 --- /dev/null +++ b/LICENSE.txt @@ -0,0 +1,11 @@ +This eBook, including all associated images, markup, improvements, +metadata, and any other content or labor, has been confirmed to be +in the PUBLIC DOMAIN IN THE UNITED STATES. + +Procedures for determining public domain status are described in +the "Copyright How-To" at https://www.gutenberg.org. + +No investigation has been made concerning possible copyrights in +jurisdictions other than the United States. Anyone seeking to utilize +this eBook outside of the United States should confirm copyright +status under the laws that apply to them. diff --git a/README.md b/README.md new file mode 100644 index 0000000..0f445ae --- /dev/null +++ b/README.md @@ -0,0 +1,2 @@ +Project Gutenberg (https://www.gutenberg.org) public repository for +eBook #54376 (https://www.gutenberg.org/ebooks/54376) diff --git a/old/54376-0.txt b/old/54376-0.txt deleted file mode 100644 index efa7240..0000000 --- a/old/54376-0.txt +++ /dev/null @@ -1,13869 +0,0 @@ -Project Gutenberg's Pleasant Ways in Science, by Richard A. Proctor - -This eBook is for the use of anyone anywhere in the United States and most -other parts of the world 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. If you are not located in the United States, you'll have -to check the laws of the country where you are located before using this ebook. - -Title: Pleasant Ways in Science - -Author: Richard A. Proctor - -Release Date: March 17, 2017 [EBook #54376] - -Language: English - -Character set encoding: UTF-8 - -*** START OF THIS PROJECT GUTENBERG EBOOK PLEASANT WAYS IN SCIENCE *** - - - - -Produced by Chris Curnow, Charlie Howard, and the Online -Distributed Proofreading Team at http://www.pgdp.net (This -file was produced from images generously made available -by The Internet Archive) - - - - - - - - - -PLEASANT WAYS IN SCIENCE. - - - - -WORKS BY RICHARD A. PROCTOR. - - - LIGHT SCIENCE FOR LEISURE HOURS: Familiar Essays on Scientific - Subjects. Crown 8vo, 3_s._ 6_d._ - - THE ORBS AROUND US: A Series of Essays on the Moon and Planets, - Meteors and Comets. With Charts and Diagrams. Crown 8vo, 3_s._ - 6_d._ - - OTHER WORLDS THAN OURS: The Plurality of Worlds Studied under the - Light of Recent Scientific Researches. With 14 Illustrations. - Crown 8vo, 3_s._ 6_d._ - - OTHER SUNS THAN OURS: A Series of Essays on Suns—Old, Young, and - Dead. With other Science Gleanings. Two Essays on Whist, and - Correspondence with Sir John Herschel. With 9 Star Maps and - Diagrams. Cr. 8vo, 3_s._ 6_d._ - - THE MOON: Her Motions, Aspects, Scenery, and Physical Condition. - With Plates, Charts, Woodcuts, &c. Crown 8vo, 3_s._ 6_d._ - - UNIVERSE OF STARS: Presenting Researches into and New Views - respecting the Constitution of the Heavens. With 22 Charts and - 22 Diagrams. 8vo, 10_s._ 6_d._ - - LARGER STAR ATLAS for the Library, in 12 Circular Maps, with - Introduction and 2 Index Pages. Folio, 15_s._; or Maps only, - 12_s._ 6_d._ - - NEW STAR ATLAS for the Library, the School, and the Observatory, - in 12 Circular Maps. Crown 8vo, 5_s._ - - HALF-HOURS WITH THE STARS: A Plain and Easy Guide to the - Knowledge of the Constellations. Showing in 12 Maps the - position of the principal Star Groups night after night - throughout the Year. With Introduction and a separate - Explanation of each Map. True for every Year. 4to, 3_s._ net. - - HALF-HOURS WITH THE TELESCOPE: A Popular Guide to the Use of - the Telescope as a means of Amusement and Instruction. With 7 - Plates. Fcp. 8vo, 2_s._ 6_d._ - - THE STARS IN THEIR SEASONS: An Easy Guide to a Knowledge of the - Star Groups, in 12 Large Maps. Imperial 8vo, 5_s._ - - THE SOUTHERN SKIES: A Plain and Easy Guide to the Constellations - of the Southern Hemisphere. Showing in 12 Maps the position - of the principal Star Groups night after night throughout the - Year. With an Introduction and a separate Explanation of each - Map. True for every Year. 4to, 5_s._ - - STAR PRIMER: Showing the Starry Sky Week by Week, in 24 Hourly - Maps. Crown 4to, 2_s._ 6_d._ - - ROUGH WAYS MADE SMOOTH: Familiar Essays on Scientific Subjects. - Crown 8vo, 3_s._ 6_d._ - - OUR PLACE AMONG INFINITIES: A Series of Essays contrasting our - Little Abode in Space and Time with the Infinities around us. - Crown 8vo, 3_s._ 6_d._ - - THE EXPANSE OF HEAVEN: Essays on the Wonders of the Firmament. - Crown 8vo, 3s. 6_d._ - - THE GREAT PYRAMID: OBSERVATORY, TOMB, AND TEMPLE. With - Illustrations. Crown 8vo, 5_s._ - - PLEASANT WAYS IN SCIENCE. Crown 8vo, 3_s._ 6_d._ - - MYTHS AND MARVELS OF ASTRONOMY. Crown 8vo, 3_s._ 6_d._ - - NATURE STUDIES. By GRANT ALLEN, A. WILSON, T. FOSTER, E. CLODD, - and R. A. PROCTOR. Crown 8vo, 3_s._ 6_d._ - - LEISURE READINGS. By E. CLODD, A. WILSON, T. FOSTER, A. C. - RANYARD, and R. A. PROCTOR. Crown 8vo, 5_s._ Cheap Edition, - 3_s._ 6_d._ - - STRENGTH: How to Get Strong and Keep Strong. With Chapters - on Rowing and Swimming, Fat, Age, and the Waist. With 9 - Illustrations. Crown 8vo, 2_s._ - - CHANCE AND LUCK: A Discussion of the Laws of Luck, Coincidences, - Wagers, Lotteries, and the Fallacies of Gambling, &c. Crown - 8vo, 2_s._ 6_d._ - - HOW TO PLAY WHIST: With the Laws and Etiquette of Whist. Crown - 8vo, 3_s._ net. - - HOME WHIST: An Easy Guide to Correct Play. 16mo, 1_s._ - - -LONDON: LONGMANS, GREEN, & CO. - - - - - PLEASANT WAYS - IN SCIENCE - - BY - RICHARD A. PROCTOR - - AUTHOR OF - “ROUGH WAYS MADE SMOOTH,” “THE EXPANSE OF HEAVEN,” “OUR PLACE - AMONG INFINITIES,” “MYTHS AND MARVELS OF ASTRONOMY,” - ETC. ETC. - - - _NEW IMPRESSION_ - - - LONGMANS, GREEN, AND CO. - 39 PATERNOSTER ROW, LONDON - NEW YORK AND BOMBAY - 1905 - - - - -CONTENTS. - - - PAGE - OXYGEN IN THE SUN 1 - - SUN-SPOT, STORM, AND FAMINE 28 - - NEW WAYS OF MEASURING THE SUN’S DISTANCE 56 - - DRIFTING LIGHT WAVES 77 - - THE NEW STAR WHICH FADED INTO STAR-MIST 106 - - STAR-GROUPING, STAR-DRIFT, AND STAR-MIST 136 - - MALLET’S THEORY OF VOLCANOES 151 - - TOWARDS THE NORTH POLE 156 - - A MIGHTY SEA-WAVE 178 - - STRANGE SEA CREATURES 199 - - ON SOME MARVELS IN TELEGRAPHY 232 - - THE PHONOGRAPH, OR VOICE-RECORDER 274 - - THE GORILLA AND OTHER APES 296 - - THE USE AND ABUSE OF FOOD 330 - - OZONE 347 - - DEW 357 - - THE LEVELLING POWER OF RAIN 367 - - ANCIENT BABYLONIAN ASTROGONY 388 - - - - -PREFACE. - - -It is very necessary that all who desire to become really proficient in -any department of science should follow the beaten track, toiling more -or less painfully over the difficult parts of the high road which is -their only trustworthy approach to the learning they desire to attain. -But there are many who wish to learn about scientific discoveries -without this special labour, for which some have, perhaps, little -taste, while many have scant leisure. My purpose in the present work, -as in my “Light Science for Leisure Hours,” the “Myths and Marvels of -Astronomy,” the “Borderland of Science,” and “Science Byways,” has been -to provide paths of easy access to the knowledge of some of the more -interesting discoveries, researches, or inquiries of the science of -the day. I wish it to be distinctly understood that my purpose is to -interest rather than to instruct, in the strict sense of the word. But -I may add that it seems to me even more necessary to be cautious, and -accurate in such a work as the present than in advanced treatises. For -in a scientific work the reasoning which accompanies the statements -of fact affords the means of testing and sometimes of correcting -such statements. In a work like the present, where explanation and -description take the place of reasoning, there is no such check. For -this reason I have been very careful in the accounts which I have given -of the subjects here dealt with. I have been particularly careful not -to present, as established truths, such views as are at present only -matters of opinion. - -The essays in the present volume are taken chiefly from the -_Contemporary Review_, the _Gentleman’s Magazine_, the _Cornhill -Magazine_, _Belgravia_, and _Chambers’ Journal_. The sixth, however, -presents the substance (and official report) of a lecture which I -delivered at the Royal Institution in May, 1870. It was then that I -first publicly enunciated the views respecting the stellar universe -which I afterwards more fully stated in my “Universe of Stars.” The -same views have also been submitted to the Paris Academy of Science, as -the results of his own investigations, by M. Flammarion, in words which -read almost like translations of passages in the above-mentioned essay. - - RICHARD A. PROCTOR. - - - - -PLEASANT WAYS IN SCIENCE. - - - - -_OXYGEN IN THE SUN._ - - -The most promising result of solar research since Kirchhoff in 1859 -interpreted the dark lines of the sun’s spectrum has recently been -announced from America. Interesting in itself, the discovery just made -is doubly interesting in what it seems to promise in the future. Just -as Kirchhoff’s great discovery, that a certain double dark line in the -solar spectrum is due to the vapour of sodium in the sun’s atmosphere, -was but the first of a long series of results which the spectroscopic -analysis of the sun was to reveal, so the discovery just announced that -a certain important gas—the oxygen present in our air and the chief -chemical constituent of water—shows its presence in the sun by bright -lines instead of dark, will in all probability turn out to be but the -firstfruits of a new method of examining the solar spectrum. As its -author, Dr. Henry Draper, of New York, remarks, further investigation -in the direction he has pursued will lead to the discovery of other -elements in the sun, but it was not “proper to conceal, for the sake -of personal advantage, the principle on which such researches are to -be conducted.” It may well happen, though I anticipate otherwise, that -by thus at once describing his method of observation, Dr. Draper may -enable others to add to the list of known solar elements some which -yet remain to be detected; but if Dr. Draper should thus have added but -one element to that list, he will ever be regarded as the physicist -to whose acumen the method was due by which all were detected, and to -whom, therefore, the chief credit of their discovery must certainly be -attributed. - -I propose briefly to consider the circumstances which preceded the -great discovery which it is now my pleasing duty to describe, in order -that the reader may the more readily follow the remarks by which I -shall endeavour to indicate some of the results which seem to follow -from the discovery, as well as the line along which, in my opinion, the -new method may most hopefully be followed. - -It is generally known that what is called the spectroscopic method -of analyzing the sun’s substance had its origin in Kirchhoff’s -interpretation of the dark lines in the solar spectrum. Until -1859 these dark lines had not been supposed to have any special -significance, or rather it had not been supposed that their -significance, whatever it might be, could be interpreted. A physicist -of some eminence spoke of these phenomena in 1858 in a tone which ought -by the way seldom to be adopted by the man of science. “The phenomena -defy, as we have seen,” he said, “all attempts hitherto to reduce them -within empirical laws, and no complete explanation or theory of them is -possible. All that theory can be expected to do is this—it may explain -how dark lines of any sort may arise within the spectrum.” Kirchhoff, -in 1859, showed not only how dark lines of any sort may appear, but how -and why they do appear, and precisely what they mean. He found that -the dark lines of the solar spectrum are due to the vapours of various -elements in the sun’s atmosphere, and that the nature of such elements -may be determined from the observed position of the dark lines. Thus -when iron is raised by the passage of the electric spark to so intense -a degree of heat that it is vaporized, the light of the glowing -vapour of iron is found to give a multitude of bright lines along the -whole length of the spectrum—that is, some red, some orange, some -yellow, and so on. In the solar spectrum corresponding dark lines are -found along the whole length of the spectrum—that is, some in the -red, some in the orange, yellow, etc., and precisely in those parts -of these various spectral regions which the bright lines of glowing -iron would occupy. Multitudes of other dark lines exist of course in -the solar spectrum. But those corresponding to the bright lines of -glowing iron are unquestionably there. They are by no means lost in -the multitude, as might be expected; but, owing to the peculiarity of -their arrangement, strength, etc., they are perfectly recognizable as -the iron lines reversed, that is, dark instead of bright. Kirchhoff’s -researches showed how this is to be interpreted. It means that the -vapour of iron exists in the atmosphere of the sun, glowing necessarily -with an intensely bright light; _but_, being cooler (however intensely -hot) than the general mass of the sun within, the iron vapour absorbs -more light than it emits, and the result is that the iron lines, -instead of appearing bright, as they would if the iron vapour alone -were shining, appear relatively dark on the bright rainbow-tinted -background of the solar spectrum. - -Thus was it shown that in the atmosphere of the sun there is the -glowing vapour of the familiar metal, iron; and in like manner other -metals, and one element (hydrogen) which is not ordinarily regarded as -a metal, were shown to be present in the sun’s atmosphere. In saying -that they are present in the sun’s atmosphere, I am, in point of fact, -saying that they are present in the sun; for the solar atmosphere is, -in fact, the outer part of the sun himself, since a very large part, -if not by far the greater part, of the sun’s mass must be vaporous. -But no other elements, except the metals iron, sodium, barium, -calcium, magnesium, aluminium, manganese, chromium, cobalt, nickel, -zinc, copper, and titanium, and the element hydrogen, were shown -to be present in the sun, by this method of observing directly the -solar dark lines. In passing, I may note that there are reasons for -regarding hydrogen as a metallic element, strange though the idea may -seem to those who regard hardness, brightness, malleability, ductility, -plasticity, and the like, as the characteristic properties of metals, -and necessarily fail to comprehend how a gas far rarer, under the -same conditions, than the air we breathe, and which cannot possibly -be malleable, ductile, or the like, can conceivably be regarded as a -metal. But there is in reality no necessary connection between any one -of the above properties and the metallic nature; many of the fifty-five -metals are wanting in all of these properties; nor is there any reason -why, as we have in mercury a metal which at ordinary temperatures is a -liquid, so we might have in hydrogen a metal which, at all obtainable -temperatures, and under all obtainable conditions of pressure, is -gaseous. It was shown by the late Professor Graham (aided in his -researches most effectively by Dr. Chandler Roberts) that hydrogen will -enter into such combination with the metal palladium that it may be -regarded as forming, for the time, with the palladium, an alloy; and -as alloys can only be regarded as compounds of two or more metals, the -inference is that hydrogen is in reality a metallic element. - -Fourteen only of the elements known to us, or less than a quarter -of the total number, were thus found to be present in the sun’s -constitution; and of these all were metals, if we regard hydrogen as -metallic. Neither gold nor silver shows any trace of its presence, -nor can any sign be seen of platinum, lead, and mercury. But, most -remarkable of all, and most perplexing, was the absence of all trace -of oxygen and nitrogen, two gases which could not be supposed wanting -in the substance of the great ruling centre of the planetary system. -It might well be believed, indeed, that none of the five metals just -named are absent from the sun, and indeed that every one of the -forty metals not recognized by the spectroscopic method nevertheless -exists in the sun. For according to the nebular hypothesis of the -origin of our solar system, the sun might be expected to contain all -the elements which exist in our earth. Some of these elements might -indeed escape discovery, because existing only in small quantities; -and others (as platinum, gold, and lead, for example), because but a -small portion of their vaporous substance rose above the level of that -glowing surface which is called the photosphere. But that oxygen, which -constitutes so large a portion of the solid, liquid, and vaporous mass -of our earth, should not exist in enormous quantities, and its presence -be very readily discernable, seemed amazing indeed. Nitrogen, also, -might well be expected to be recognizable in the sun. Carbon, again, -is so important a constituent of the earth, that we should expect to -discover clear traces of its existence in the sun. In less degree, -similar considerations apply to sulphur, boron, silicon, and the other -non-metallic elements. - -It was not supposed, however, by any one at all competent to form an -opinion on the subject, that oxygen, nitrogen, and carbon are absent -from the sun. It was perceived that an element might exist in enormous -quantities in the substance of the sun, and yet fail to give any -evidence of its presence, or only give such evidence as might readily -escape recognition. If we remember how the dark lines are really -caused, we shall perceive that this is so. A glowing vapour in the -atmosphere of the sun absorbs rays of the same colour as it emits. If -then, it is cooler than the glowing mass of the sun which it enwraps, -and if, notwithstanding the heat received from this mass, it remains -cooler, then it suffers none of those rays to pass earthwards.[1] It -emits rays of the same kind (that is, of the same _colour_) itself, -but, being cooler, the rays thus coming from it are feebler; or, to -speak more correctly, the ethereal waves thus originated are feebler -than those of the same order which _would_ have travelled earthwards -from the sun but for the interposed screen of vapour. Hence the -corresponding parts of the solar spectrum are less brilliant, and -contrasted with the rainbow-tinted streak of light, on which they lie -as on a background, they appear dark. - -In order, then, that any element may be detected by its dark lines, it -is necessary that it should lie as a vaporous screen between the more -intensely heated mass of the sun and the eye of the observer on earth. -It must then form an enclosing envelope cooler than the sun within it. -Or rather, some part of the vapour must be thus situated. For enormous -masses of the vapour might be within the photospheric surface of the -sun at a much higher temperature, which yet, being enclosed in the -cooler vaporous shell of the same substance, would not be able to send -its light rays earthwards. One may compare the state of things, so -far as that particular element is concerned, to what is presented in -the case of a metallic globe cooled on the outside but intensely hot -within. The cool outside of such a globe is what determines the light -and heat received from it, so long as the more heated mass within has -not yet (by conduction) warmed the exterior shell. So in the case of -a vapour permeating the entire mass, perhaps, of the sun, and at as -high a temperature as the sun everywhere except on the outside: it is -the temperature of the outermost part of such a vaporous mass which -determines the intensity of the rays received from it—or in other -words, determines whether the corresponding parts of the spectrum shall -be darker or not than the rest of the spectrum. If the vapour does -not rise above the photosphere of the sun in sufficient quantity to -exercise a recognizable absorptive effect, its presence in the sun will -not be indicated by any dark lines. - -I dwell here on the question of quantity, which is sometimes overlooked -in considering the spectroscopic evidence of the sun’s condition, but -is in reality a very important factor in determining the nature of the -evidence relating to each element in the solar mass. In some cases, -the quantity of a material necessary to give unmistakable spectroscopic -evidence is singularly small; insomuch that new elements, as thallium, -cæsium, rubidium, and gallium, have been actually first recognized -by their spectral lines when existing in such minute quantities in -the substances examined as to give no other trace whatever of their -existence. But it would be altogether a mistake to suppose that some -element existing in exceedingly small quantities, or, more correctly, -existing in the form of an exceedingly rare vapour in the sun’s -atmosphere, would be detected by means of its dark lines, or _by any -other method depending on the study of the solar spectrum_. When we -place a small portion of some substance in the space between the carbon -points of an electric lamp, and volatilize that substance in the -voltaic arc, we obtain a spectrum including all the bright lines of the -various elements contained in the substance; and if some element is -contained in it in exceedingly small quantity, we may yet perceive its -distinctive bright lines among the others (many of them far brighter) -belonging to the elements present in greater quantities. But if we have -(for example) a great mass of molten iron, the rainbow-tinted spectrum -of whose light we examine from a great distance, and if a small -quantity of sodium, or other substance which vaporizes at moderate -temperatures, be cast into the molten iron so that the vapour of the -added element presently rises above the glowing surface of the iron, -no trace of the presence of this vapour would be shown in the spectrum -observed from a distance. The part of the spectrum where the dark lines -of sodium usually appear would, undoubtedly, be less brilliant than -before, in the same sense that the sun may be said to be less brilliant -when the air is in the least degree moist than when it is perfectly -dry; but the loss of brilliancy is as utterly imperceptible in the one -case as it is in the other. In like manner, a vapour might exist in -the atmosphere of the sun (above the photosphere, that is), of whose -presence not a trace would be afforded in the spectroscope, for the -simple reason that the absorptive action of the vapour, though exerted -to reduce the brightness of particular solar rays or tints, would not -affect those rays sufficiently for the spectroscopist to recognize any -diminution of their lustre. - -There is another consideration, which, so far as I know, has not -hitherto received much attention, but should certainly be taken into -account in the attempt to interpret the real meaning of the solar -spectrum. Some of the metals which are vaporized by the sun’s heat -below the photosphere may become liquid or even solid at or near the -level of the photosphere. Even though the heat at the level of the -photosphere may be such that, under ordinary conditions of pressure and -so forth, such metals would be vaporous, the enormous pressure which -must exist not far below the level of the photosphere may make the -heat necessary for complete vaporization far greater than the actual -heat at that level. In that case the vapour will in part condense into -liquid globules, or, if the heat is considerably less than is necessary -to keep the substance in the form of vapour, then it may in part be -solidified, the tiny globules of liquid metal becoming tiny crystals -of solid metal. We see both conditions fulfilled within the limits of -our own air in the case of the vapour of water. Low down the water -is present in the air (ordinarily) in the form of pure vapour; at a -higher level the vapour is condensed by cold into liquid drops forming -visible clouds (cumulus clouds), and yet higher, where the cold is -still greater, the minute water-drops turn into ice-crystals, forming -those light fleecy clouds called cirrus clouds by the meteorologist. -Now true clouds of either sort may exist in the solar atmosphere even -above that photospheric level which forms the boundary of the sun we -see. It may be said that the spectroscope, applied to examine matter -outside the photosphere, has given evidence only of vaporous cloud -masses. The ruddy prominences which tower tens of thousands of miles -above the surface of the sun, and the sierra (or as it is sometimes -unclassically called, the chromosphere) which covers usually the -whole of the photosphere to a depth of about eight thousand miles, -show only, under spectroscopic scrutiny, the bright lines indicating -gaseity. But though this is perfectly true, it is also true that we -have not here a particle of evidence to show that clouds of liquid -particles, and of tiny crystals, may not float over the sun’s surface, -or even that the ruddy clouds shown by the spectroscope to shine with -light indicative of gaseity may not also contain liquid and crystalline -particles. For in point of fact, the very principle on which our -recognition of the bright lines depends involves the inference that -matter whose light would _not_ be resolved into bright lines would -not be recognizable at all. The bright lines are seen, because by -means of a spectroscope we can throw them far apart, without reducing -their lustre, while the background of rainbow-tinted spectrum has its -various portions similarly thrown further apart and correspondingly -weakened. One may compare the process (the comparison, I believe, has -not hitherto been employed) to the dilution of a dense liquid in which -solid masses have been floating: the more we increase the quantity of -the liquid in diluting it with water, the more transparent it becomes, -but the solid masses in it are not changed, so that we only have to -dilute the liquid sufficiently to see these masses. _But_ if there were -in the interstices of the solid masses particles of some substance -which dissolved in the water, we should not recognize the presence of -this substance by any increase in its visibility; for the very same -process which thinned the liquid would thin this soluble substance in -the same degree. In like manner, by dispersing and correspondingly -weakening the sun’s light more and more, we can recognize the light of -the gaseous matter in the prominences, for this is not weakened; but if -the prominences also contain matter in the solid or liquid form (that -is, drops or crystals), the spectroscopic method will not indicate the -presence of such matter, for the spectrum of matter of this sort will -be weakened by dispersion in precisely the same degree that the solar -spectrum itself is weakened. - -It is easy to see how the evidence of the presence of any element -which behaved in this way would be weakened, if we consider what would -happen in the case of our own earth, according as the air were simply -moist but without clouds, or loaded with cumulus masses but without -cirrus clouds, or loaded with cirrus clouds. For although there is not -in the case of the earth a central glowing mass like the sun’s, on -whose rainbow-tinted spectrum the dark lines caused by the absorptive -action of our atmosphere could be seen by the inhabitant of some -distant planet studying the earth from without, yet the sun’s light -reflected from the surface of the earth plays in reality a similar -part. It does not give a simple rainbow-tinted spectrum; for, being -sunlight, it shows all the dark lines of the solar spectrum: but the -addition of new dark lines to these, in consequence of the absorptive -action of the earth’s atmosphere, could very readily be determined. In -fact, we do thus recognize in the spectra of Mars, Venus, and other -planets, the presence of aqueous vapour in their atmosphere, despite -the fact that our own air, containing also aqueous vapour, naturally -renders so much the more difficult the detection of that vapour in the -atmosphere of remote planets necessarily seen through our own air. -Now, a distant observer examining the light of our own earth on a day -when, though the air was moist, there were no clouds, would have ample -evidence of the presence of the vapour of water; for the light which he -examined would have gone twice through our earth’s atmosphere, from its -outermost thinnest parts to the densest layers close to the surface, -then back again through the entire thickness of the air. But if the -air were heavily laden with cumulus clouds (without any cirrus clouds -at a higher layer), although _we_ should know that there was abundant -moisture in the air, and indeed much more moisture then there had been -when there had been no clouds, our imagined observer would either -perceive no traces at all of this moisture, or he would perceive traces -so much fainter than when the air was clear that he would be apt to -infer that the air was either quite dry, or at least very much drier -than it had been in that case. For the light which he would receive -from the earth would not in this case have passed through the entire -depth of moisture-laden air twice, but twice only through that portion -of the air which lay above the clouds, at whose surface the sun’s light -would be reflected. The whole of the moisture-laden layer of the air -would be snugly concealed under the cloud-layer, and would exercise -no absorptive action whatever on the light which the remote observer -would examine. If from the upper surface of the layer of cumulus clouds -aqueous vapour rose still higher, and were converted in the cold upper -regions of the atmosphere into clouds of ice-crystals, the distant -observer would have still less chance of recognizing the presence of -moisture in our atmosphere. For the layer of air between the cumulus -clouds and the cirrus clouds would be unable to exert any absorptive -action on the light which reached the observer. All such light would -come to him after reflection from the layer of cirrus clouds. He would -be apt to infer that there was no moisture at all in the air of our -planet, at the very time when in fact there was so much moisture that -not one layer only, but two layers of clouds enveloped the earth, the -innermost layer consisting of particles of liquid water, the outermost -of particles of frozen water. Using the words ice, water, and steam, -to represent the solid, liquid, and vaporous states of water, we may -fairly say that ice and water, by hiding steam, would persuade the -remote observer that there was no water at all on the earth—at least -if he trusted solely to the spectroscopic evidence then obtained.[2] - -We might in like manner fail to obtain any spectroscopic evidence of -the presence of particular elements in the sun, because they do not -exist in sufficient quantity in the vaporous form in those outer layers -which the spectroscope can alone deal with. - -In passing, I must note a circumstance in which some of those who have -dealt with this special part of the spectroscopic evidence have erred. -It is true in one sense that some elements may be of such a nature that -their vapours cannot rise so high in the solar atmosphere as those of -other elements. But it must not be supposed that the denser vapours -seek a lower level, the lighter vapours rising higher. According to -the known laws of gaseous diffusion, a gas or vapour diffuses itself -throughout a space occupied by another gas or several other gases, -in the same way as though the space were not occupied at all. If we -introduce into a vessel full of common air a quantity of carbonic -acid gas (I follow the older and more familiar nomenclature), this -gas, although of much higher specific gravity than either oxygen or -nitrogen, does not take its place at the bottom of the vessel, but so -diffuses itself that the air of the upper part of the vessel contains -exactly the same quantity of carbonic acid gas as the air of the -lower part. Similarly, if hydrogen is introduced, it does not seek -the upper part of the vessel, but diffuses itself uniformly throughout -the vessel. If we enclose the carbonic acid gas in a light silken -covering, and the hydrogen in another (at the same pressure as the air -in the vessel) one little balloon will sink and the other will rise; -but this is simply because diffusion is prevented. It may be asked -how this agrees with what I have said above, that some elements may -not exist in sufficient quantity or in suitable condition above the -sun’s photospheric level to give any spectroscope evidence of their -nature. As to quantity, indeed, the answer is obvious: if there is only -a small quantity of any given element in the entire mass of the sun, -only a very small quantity can under any circumstances exist outside -the photosphere. As regards condition, it must be remembered that the -vessel of my illustrative case was supposed to contain air at a given -temperature and pressure throughout. If the vessel was so large that -in different parts of it the temperature and pressure were different, -the diffusion would, indeed, still be perfect, because at all ordinary -temperatures and pressures hydrogen and carbonic acid gas remain -gaseous. But if the vapour introduced is of such a nature that at -moderate temperatures and pressures it condenses, wholly or in part, or -liquefies, the diffusion will not take place with the same uniformity. -We need not go further for illustration than to the case of our own -atmosphere as it actually exists. The vapour of water spreads uniformly -through each layer of the atmosphere which is at such a temperature -and pressure as to permit of such diffusion; but where the temperature -is too low for complete diffusion (at the actual pressure) the aqueous -vapour is condensed into visible cloud, diffusion being checked at -this point as at an impassable boundary. In the case of the sun, as -in the case of our own earth, it is not the density of an element -when in a vaporous form which limits its diffusion, but the value -of the temperature at which its vapour at given pressure condenses -into liquid particles. It is in this way only that any separation can -be effected between the various elements which exist in the sun’s -substance. A separation of this sort is unquestionably competent to -modify the spectroscopic evidence respecting different elements. But -it would be a mistake to suppose that any such separation could occur -as has been imagined by some—a separation causing in remote times -the planets supposed to have been thrown off by the sun to be rarest -on the outskirts of the solar system and densest close to the sun. -The small densities of the outer family of planets, as compared with -the densities of the so-called terrestrial planets, must certainly be -otherwise explained. - -But undoubtedly the chief circumstance likely to operate in veiling -the existence of important constituents of the solar mass must be that -which has so long prevented spectroscopists from detecting the presence -of oxygen in the sun. An element may exist in such a condition, either -over particular parts of the photosphere, or over the entire surface -of the sun, that instead of causing dark lines in the solar spectrum -it may produce bright lines. Such lines may be conspicuous, or they -may be so little brighter than the background of the spectrum as to be -scarcely perceptible or quite imperceptible. - -In passing, I would notice that this interpretation of the want of all -spectroscopic evidence of the presence of oxygen, carbon, and other -elements in the sun, is not an _ex post facto_ explanation. As will -presently appear, it is now absolutely certain that oxygen, though -really existing, and doubtless, in enormous quantities, in the sun, has -been concealed from recognition in this way. But that this might be so -was perceived long ago. I myself, in the first edition of my treatise -on “The Sun,” pointed out, in 1870, with special reference to nitrogen -and oxygen, that an element “may be in a condition enabling it to -radiate as much light as it absorbs, or else very little more or very -little less; so that it either obliterates all signs of its existence, -or else gives lines so little brighter or darker than the surrounding -parts of the spectrum that we can detect no trace of its existence.” -I had still earlier given a similar explanation of the absence of all -spectroscopic evidence of hydrogen in the case of the bright star -Betelgeux.[3] - -Let us more closely consider the significance of what we learn from -the spectral evidence respecting the gas hydrogen. We know that when -the total light of the sun is dealt with, the presence of hydrogen is -constantly indicated by dark lines. In other words, regarding the sun -as a whole, hydrogen constantly reduces the emission of rays of those -special tints which correspond to the light of this element. When we -examine the light of other suns than ours, we find that in many cases, -probably in by far the greater number of cases, hydrogen acts a similar -part. But not in every case. In the spectra of some stars, notably in -those of Betelgeux and Alpha Herculis, the lines of hydrogen are not -visible at all; while in yet others, as Gamma Cassiopeiæ, the middle -star of the five which form the straggling W of this constellation, -the lines of hydrogen show bright upon the relatively dark background -of the spectrum. When we examine closely the sun himself, we find that -although his light as a whole gives a spectrum in which the lines of -hydrogen appear dark, the light of particular parts of his surface, -if separately examined, occasionally shows the hydrogen lines bright -as in the spectrum of Gamma Cassiopeiæ, while sometimes the light of -particular parts gives, like the light of Betelgeux, no spectroscopic -evidence whatever of the presence of hydrogen. Manifestly, if the whole -surface of the sun were in the condition of the portions which give -bright hydrogen lines, the spectrum of the sun would resemble that of -Gamma Cassiopeiæ; while if the whole surface were in the condition of -those parts which show no lines of hydrogen, the spectrum of the sun -would resemble that of Betelgeux. Now if there were any reason for -supposing that the parts of the sun which give no lines of hydrogen -are those from which the hydrogen has been temporarily removed in some -way, we might reasonably infer that in the stars whose spectra show no -hydrogen lines there is no hydrogen. But the fact that the hydrogen -lines are sometimes seen bright renders this supposition untenable. -For we cannot suppose that the lines of hydrogen change from dark -to bright or from bright to dark (both which changes certainly take -place) without passing through a stage in which they are neither bright -nor dark; in other words, we are compelled to assume that there is -an intermediate condition in which the hydrogen lines, though really -existent, are invisible because they are of precisely the same lustre -as the adjacent parts of the spectrum. Hence the evanescence of the -hydrogen lines affords no reason for supposing that hydrogen has become -even reduced in quantity where the lines are not seen. And therefore -it follows that the invisibility of the hydrogen lines in the spectrum -of Betelgeux is no proof that hydrogen does not exist in that star in -quantities resembling those in which it is present in the sun. And -this, being demonstrated in the case of one gas, must be regarded as -at least probable in the case of other gases. Wherefore the absence of -the lines of oxygen from the spectrum of any star affords no sufficient -reason for believing that oxygen is not present in that star, or that -it may not be as plentifully present as hydrogen, or even far more -plentifully present. - -There are other considerations which have to be taken into account, as -well in dealing with the difficulty arising from the absence of the -lines of particular elements from the solar spectrum as in weighing the -extremely important discovery which has just been effected by Dr. H. -Draper. - -I would specially call attention now to a point which I thus presented -seven years ago:—“The great difficulty of interpreting the results -of the spectroscopic analysis of the sun arises from the circumstance -that we have no means of learning whence that part of the light comes -which gives the continuous spectrum. When we recognize certain dark -lines, we know certainly that the corresponding element exists in the -gaseous form at a lower temperature than the substance which gives the -continuous spectrum. But as regards that continuous spectrum itself -we can form no such exact opinion.” It might, for instance, have -its origin in glowing liquid or solid matter; but it might also be -compounded of many spectra, each containing a large number of bands, -the bands of one spectrum filling up the spaces which would be left -dark between the bands of another spectrum, and so on until the entire -range from the extreme visible red to the extreme visible violet were -occupied by what appeared as a continuous rainbow-tinted streak. “We -have, in fact, in the sun,” as I pointed out, “a vast agglomeration -of elements, subject to two giant influences, producing in some sort -opposing effects—viz., a temperature far surpassing any we can form -any conception of, and a pressure (throughout nearly the whole of -the sun’s globe) which is perhaps even more disproportionate to the -phenomena of our experience. Each known element would be vaporized by -the solar temperature at known pressures; each (there can be little -question) would be solidified by the vast pressures, did these arise -at known temperatures. Now whether, under these circumstances, the -laws of gaseous diffusion prevail where the elements _are_ gaseous in -the solar globe; whether, where liquid matter exists it is in general -bounded in a definite manner from the neighbouring gaseous matter; -whether any elements at all are solid, and if so under what conditions -their solidity is maintained and the limits of the solid matter -defined—all these are questions which _must_ be answered before we -can form a satisfactory idea of the solar constitution; yet they are -questions which we have at present no means of answering.” Again, we -require to know whether any process resembling combustion can under -any circumstances take place in the sun’s globe. If we could assume -that some general resemblance exists between the processes at work upon -the sun and those we are acquainted with, we might imagine that the -various elements ordinarily exist in the sun’s globe in the gaseous -form (chiefly) to certain levels, to others chiefly in the liquid form, -and to yet others chiefly in the solid form. But even then that part -of each element which is gaseous may exist in two forms, having widely -different spectra (in reality in five, but I consider only the extreme -forms). The light of one part is capable of giving characteristic -spectra of lines or bands (which will be different according to -pressure and may appear either dark or bright); that of the other is -capable of giving a spectrum nearly or quite continuous. - -It will be seen that Dr. H. Draper’s discovery supplies an answer to -one of the questions, or rather to one of the sets of questions, thus -indicated. I give his discovery as far as possible in his own words. - -“_Oxygen discloses itself_,” he says, “_by bright lines or bands in -the solar spectrum_, and does not give dark absorption-lines like the -metals. We must therefore change our theory of the solar spectrum, -and no longer regard it merely as a continuous spectrum with certain -rays absorbed by a layer of ignited metallic vapours, but as having -also bright lines and bands superposed on the background of continuous -spectrum. Such a conception not only opens the way to the discovery -of others of the non-metals, sulphur, phosphorus, selenium, chlorine, -bromine, iodine, fluorine, carbon, etc., but also may account for some -of the so-called dark lines, by regarding them as intervals between -bright lines. It must be distinctly understood that in speaking of the -solar spectrum here, I do not mean the spectrum of any limited area -upon the disc or margin of the sun, but the spectrum of light from the -whole disc.” - -In support of the important statement here advanced, Dr. Draper submits -a photograph of part of the solar spectrum with a comparison spectrum -of air, and also with some of the lines of iron and aluminium. The -photograph itself, a copy of which, kindly sent to me by Dr. Draper, -lies before me as I write, fully bears out Dr. Draper’s statement. It -is absolutely free from handwork or retouching, except that reference -letters have been added in the negative. It shows the part of the solar -spectrum between the well-known Fraunhofer lines G and H, of which G -(an iron line) lies in the indigo, and H (a line of hydrogen) in the -violet, so that the portion photographed belongs to that region of -the spectrum whose chemical or actinic energy is strongest. Adjacent -to this lies the photograph of the air lines, showing nine or ten -well-defined oxygen lines or groups of lines, and two nitrogen bands. -The exact agreement of the two spectra in position is indicated by -the coincidence of bright lines of iron and aluminium included in the -air spectrum with the dark lines of the same elements in the solar -spectrum. “No close observation,” as Dr. Draper truly remarks, “is -needed to demonstrate to even the most casual observer” (of this -photograph) “that the oxygen lines are found in the sun as bright -lines.” There is in particular one quadruple group of oxygen lines in -the air spectrum, the coincidence of which with a group of bright lines -in the solar spectrum is unmistakable. - -“This oxygen group alone is almost sufficient,” says Dr. Draper, “to -prove the presence of oxygen in the sun, for not only does each of -the four components have a representative in the solar group, but the -relative strength and the general aspect of the lines in each case is -similar.[4] I shall not attempt at this time,” he proceeds, “to give -a complete list of the oxygen lines, ... and it will be noticed that -some lines in the air spectrum which have bright anologues in the sun -are not marked with the symbol of oxygen. This is because there has not -yet been an opportunity to make the necessary detailed comparisons. In -order to be certain that a line belongs to oxygen, I have compared, -under various pressures, the spectra of air, oxygen, nitrogen, carbonic -acid, carburetted hydrogen, hydrogen, and cyanogen. - -“As to the spectrum of nitrogen and the existence of this element in -the sun there is not yet certainty. Nevertheless, even by comparing -the diffused nitrogen lines of this particular photograph, in which -nitrogen has been sacrificed to get the best effect for oxygen, the -character of the evidence appears. There is a triple band somewhat -diffused in the photograph belonging to nitrogen, which has its -appropriate representative in the solar spectrum, and another band of -nitrogen is similarly represented.” Dr. Draper states that “in another -photograph a heavy nitrogen line which in the present one lies opposite -an insufficiently exposed part of the solar spectrum, corresponds to a -comparison band in the sun.” - -But one of the most remarkable points in Dr. Draper’s paper is what -he tells us respecting the visibility of these lines in the spectrum -itself. They fall, as I have mentioned, in a part of the spectrum where -the actinic energy is great but the luminosity small; in fact, while -this part of the spectrum is the very strongest for photography, it is -close to the region of the visible spectrum, - - “Where the last gleamings of refracted light - Die in the fainting violet away.” - -It is therefore to be expected that those, if any, of the bright lines -of oxygen, will be least favourably shown for direct vision, and most -favourably for what might almost be called photographic vision, where -we see what photography records for us. Yet Dr. Draper states that -these bright lines of oxygen can be readily seen. “The bright lines -of oxygen in the spectrum of the solar disc have not been hitherto -perceived, probably from the fact that in eye-observation bright lines -on a less bright background do not make the impression on the mind that -dark lines do. When attention is called to their presence they are -readily enough seen, even without the aid of a reference spectrum. The -photograph, however, brings them into greater prominence.” As the lines -of oxygen are not confined to the indigo and violet, we may fairly hope -that the bright lines in other parts of the spectrum of oxygen may be -detected in the spectrum of the sun, now that spectroscopists know that -bright lines and not dark lines are to be looked for. - -Dr. Draper remarks that from purely theoretic considerations derived -from terrestrial chemistry, and the nebular hypothesis, the presence of -oxygen in the sun might have been strongly suspected; for this element -is currently stated to form eight-ninths of the water of the globe, -one-third of the crust of the earth, and one-fifth of the air, and -should therefore probably be a large constituent of every member of the -solar system. On the other hand, the discovery of oxygen, and probably -other non-metals, in the sun gives increased strength to the nebular -hypothesis, because to many persons the absence of this important group -has presented a considerable difficulty. I have already remarked on the -circumstance that we cannot, according to the known laws of gaseous -diffusion, accept the reasoning of those who have endeavoured to -explain the small density of the outer planets by the supposition that -the lighter gases were left behind by the great contracting nebulous -mass, out of which, on the nebular hypothesis, the solar system is -supposed to have been formed. It is important to notice, now, that if -on the one hand we find in the community of structure between the sun -and our earth, as confirmed by the discovery of oxygen and nitrogen -in the sun, evidence favouring the theory according to which all the -members of that system were formed out of what was originally a single -mass, we do not find evidence against the theory (as those who have -advanced the explanation above referred to may be disposed to imagine) -in the recognition in the sun’s mass of enormous quantities of one -of these elements which, according to their view, ought to be found -chiefly in the outer members of the solar system. If those who believe -in the nebular hypothesis (generally, that is, for many of the details -of the hypothesis as advanced by Laplace are entirely untenable in -the present position of physical science) had accepted the attempted -explanation of the supposed absence of the non-metallic elements in the -sun, they would now find themselves in a somewhat awkward position. -They would, in fact, be almost bound logically to reject the nebular -hypothesis, seeing that one of the asserted results of the formation of -our system, according to that hypothesis, would have been disproved. -But so far as I know no supporter of the nebular hypothesis possessing -sufficient knowledge of astronomical facts and physical laws to render -his opinion of any weight, has ever given in his adhesion to the -unsatisfactory explanation referred to. - -The view which I have long entertained respecting the growth of the -solar system—viz., that it had its origin, not in contraction only or -chiefly, but in combined processes of contraction and accretion—seems -to me to be very strongly confirmed by Dr. Draper’s discovery. This -would not be the place for a full discussion of the reasons on which -this opinion is based. But I may remark that I believe no one who -applies the laws of physics, _as at present known_, to the theory of -the simple contraction of a great nebulous mass formerly extending -far beyond the orbit of Neptune, till, when planet after planet had -been thrown off, the sun was left in his present form and condition -in the centre, will fail to perceive enormous difficulties in the -hypothesis, or to recognize in Dr. Draper’s discovery a difficulty -added to those affecting the hypothesis _so presented_. Has it ever -occurred, I often wonder, to those who glibly quote the nebular theory -as originally propounded, to inquire how far some of the processes -suggested by Laplace are in accordance with the now known laws of -physics? To begin with, the original nebulous mass extending to a -distance exceeding the earth’s distance from the sun more than thirty -times (this being only the distance of Neptune), if we assign to it a -degree of compression making its axial diameter half its equatorial -diameter, would have had a volume exceeding the sun’s (roughly) about -120,000,000,000 times, and in this degree its mean density would have -been less than the sun’s. This would correspond to a density equal -(roughly) to about one-400,000th part of the density of hydrogen gas at -atmospheric pressure. To suppose that a great mass of matter, having -this exceedingly small mean density, and extending to a distance of -three or four thousand millions of miles from its centre, could under -any circumstances rotate as a whole, or behave in other respects after -the fashion attributed to the gaseous embryon of the solar system -in ordinary descriptions of the nebular hypothesis, is altogether -inconsistent with correct ideas of physical and dynamical laws. It is -absolutely a necessity of any nebular hypothesis of the solar system, -that from the very beginning a central nucleus and subordinate nuclei -should form in it, and grow according to the results of the motions (at -first to all intents and purposes independent) of its various parts. -Granting this state of things, we arrive, by considering the combined -effects of accretion and contraction, at a process of development -according fully as well as that ordinarily described with the general -relations described by Laplace, and accounting also (in a general way) -for certain peculiarities which are in no degree explained by the -ordinary theory. Amongst these may specially be noted the arrangement -and distribution of the masses within the solar system, and the fact -that so far as spectroscopic evidence enables us to judge, a general -similarity of structure exists throughout the whole of the system. - -Inquiring as to the significance of his discovery, Dr. Draper remarks -that it seems rather difficult “at first sight to believe that an -ignited[5] gas in the solar atmosphere should not be indicated by dark -lines in the solar spectrum, and should appear not to act under the -law, ‘a gas when ignited absorbs rays of the same refrangibility as -those it emits.’ But, in fact, the substances hitherto investigated in -the sun are really metallic vapours, hydrogen probably coming under -that rule. The non-metals obviously may behave differently. It is easy -to speculate on the causes of such behaviour; and it may be suggested -that the reason of the non-appearance of a dark line may be that -the intensity of the light from a great thickness of ignited oxygen -overpowers the effect of the photosphere, just as, if a person were to -look at a candle-flame through a yard thickness of sodium vapour, he -would only see bright sodium lines, and no dark absorption.” - -The reasoning here is not altogether satisfactory (or else is not -quite correctly expressed). In the first place, the difficulty dealt -with has no real existence. The law that a gas when glowing absorbs -rays of the same refrangibility as it emits, does not imply that a -gas between a source of light and the observer will show its presence -by spectroscopic dark lines. A gas so placed _does_ receive from the -source of light rays corresponding to those which it emits itself, if -it is cooler than the source of light; and it absorbs them, being in -fact heated by means of them, though the gain of temperature may be -dissipated as fast as received; but if the gas is hotter, it emits more -of those rays than it absorbs, and will make its presence known by its -bright lines. This is not a matter of speculation, but of experiment. -On the other hand, the experiment suggested by Dr. Draper would not -have the effect he supposes, if it were correctly made. Doubtless, -if the light from a considerable area of dully glowing sodium vapour -were received by the spectroscope at the same time as the light of a -candle-flame seen through the sodium vapour, the light of the sodium -vapour overcoming that of the candle-flame would indicate its presence -by bright lines; but if light were received only from that portion of -the sodium vapour which lay between the eye and the candle-flame, then -I apprehend that the dark lines of sodium would not only be seen, but -would be conspicuous by their darkness. - -It is in no cavilling spirit that I indicate what appears to me -erroneous in a portion of Dr. Draper’s reasoning on his great -discovery. The entire significance of the discovery depends on the -meaning attached to it, and therefore it is most desirable to ascertain -what this meaning really is. There can be no doubt, I think, that we -are to look for the true interpretation of the brightness of the oxygen -lines in the higher temperature of the oxygen, not in the great depth -of oxygen above the photospheric level. The oxygen which produces -these bright lines need not necessarily be above the photosphere at -all. (In fact, I may remark here that Dr. Draper, in a communication -addressed to myself, mentions that he has found no traces at present -of oxygen above the photosphere, though I had not this circumstance -in my thoughts in reasoning down to the conclusion that the part of -the oxygen effective in showing these bright lines lies probably below -the visible photosphere.) Of course, if the photosphere were really -composed of glowing solid and liquid matter, or of masses of gas so -compressed and so intensely heated as to give a continuous spectrum, -no gas existing below the photosphere could send its light through, -nor could its presence, therefore, be indicated in any spectroscopic -manner. But the investigations which have been made into the structure -of the photosphere as revealed by the telescope, and in particular the -observations made by Professor Langley, of the Alleghany Observatory, -show that we have not in the photosphere a definite bounding envelope -of the sun, but receive light from many different depths below that -spherical surface, 425,000 miles from the sun’s centre, which we call -the photospheric level. We receive more light from the centre of -the solar disc, I feel satisfied, not solely because the absorptive -layer through which we there see the sun is shallower, but partly, -and perhaps chiefly, because we there receive light from some of the -interior and more intensely heated parts of the sun.[6] Should this -prove to be the case, it may be found possible to do what heretofore -astronomers have supposed to be impossible—to ascertain in some degree -how far and in what way the constitution of the sun varies below the -photosphere, which, so far as ordinary telescopic observation is -concerned, seems to present a limit below which researches cannot be -pursued. - -I hope we shall soon obtain news from Dr. Huggins’s Observatory that -the oxygen lines have been photographed, and possibly the bright lines -of other elements recognized in the solar spectrum. Mr. Lockyer also, -we may hope, will exercise that observing skill which enabled him early -to recognize the presence of bright hydrogen lines in the spectrum -of portions of the sun’s surface, to examine that spectrum for other -bright lines. - -I do not remember any time within the last twenty years when the -prospects of fresh solar discoveries seemed more hopeful than they do -at present. The interest which has of late years been drawn to the -subject has had the effect of enlisting fresh recruits in the work of -observation, and many of these may before long be heard of as among -those who have employed Dr. Draper’s method successfully. - -But I would specially call attention to the interest which attaches -to Dr. Draper’s discovery and to the researches likely to follow from -it, in connection with a branch of research which is becoming more -and more closely connected year by year with solar investigations—I -mean stellar spectroscopy. We have seen the stars divided into orders -according to their constitution. We recognize evidence tending to show -that these various orders depend in part upon age—not absolute but -relative age. There are among the suns which people space some younger -by far than our sun, others far older, and some in a late stage of -stellar decrepitude. Whether as yet spectroscopists have perfectly -succeeded in classifying these stellar orders in such sort that the -connection between a star’s spectrum and the star’s age can be at -once determined, may be doubtful. But certainly there are reasons for -hoping that before long this will be done. Amongst the stars, and -(strange to say) among celestial objects which are not stars, there -are suns in every conceivable stage of development, from embryon -masses not as yet justly to be regarded as suns, to masses which have -ceased to fulfil the duties of suns. Among the more pressing duties of -spectroscopic analysis at the present time is the proper classification -of these various orders of stars. Whensoever that task shall have been -accomplished, strong light, I venture to predict, will be thrown on our -sun’s present condition, as well as on his past history, and on that -future fate upon which depends the future of our earth. - - - - -_SUN-SPOT, STORM, AND FAMINE._ - - -During the last five or six years a section of the scientific world -has been exercised with the question how far the condition of the -sun’s surface with regard to spots affects our earth’s condition as to -weather, and therefore as to those circumstances which are more or less -dependent on weather. Unfortunately, the question thus raised has not -presented itself alone, but in company with another not so strictly -scientific, in fact, regarded by most men of science as closely related -to personal considerations—the question, namely, whether certain -indicated persons should or should not be commissioned to undertake the -inquiry into the scientific problem. But the scientific question itself -ought not to be less interesting to us because it has been associated, -correctly or not, with the wants and wishes of those who advocate -the endowment of science. I propose here to consider the subject in -its scientific aspect only, and apart from any bias suggested by the -appeals which have been addressed to the administrators of the public -funds. - -It is hardly necessary to point out, in the first place, that all -the phenomena of weather are directly referable to the sun as their -governing cause. His rays poured upon our air cause the more important -atmospheric currents directly. Indirectly they cause modifications -of these currents, because where they fall on water or on moist -surfaces they raise aqueous vapour into the air, which, when it -returns to the liquid form as cloud, gives up to the surrounding air -the heat which had originally vaporized the water. In these ways, -directly or indirectly, various degrees of pressure and temperature -are brought about in the atmospheric envelope of the earth, and, -speaking generally, all air currents, from the gentlest zephyr to the -fiercest tornado, are the movements by which the equilibrium of the -air is restored. Like other movements tending to restore equilibrium, -the atmospheric motions are oscillatory. Precisely as when a spring -has been bent one way, it flies not back only, but beyond the mean -position, till it is almost equally bent the other way, so the current -of air which rushes in towards a place of unduly diminished pressure -does more than restore the mean pressure, so that presently a return -current carries off the excess of air thus carried in. We may say, -indeed, that the mean pressure at any place scarcely ever exists, and -when it exists for a time the resulting calm is of short duration. -Just as the usual condition of the sea surface is one of disturbance, -greater or less, so the usual condition of the air at every spot on -the earth’s surface is one of motion not of quiescence. Every movement -of the air, thus almost constantly perturbed, is due directly or -indirectly to the sun. - -So also every drop of rain or snow, every particle of liquid or of -frozen water in mist or in cloud, owes its birth to the sun. The -questions addressed of old to Job, “Hath the rain a father? or who -hath begotten the drops of dew? out of whose womb came the ice? and -the hoary frost of heaven, who hath gendered it?” have been answered -by modern science, and to every question the answer is, The Sun. He -is parent of the snow and hail, as he is of the moist warm rains of -summer, of the ice which crowns the everlasting hills, and of the mist -which rises from the valleys beneath his morning rays. - -Since, then, the snow that clothes the earth in winter as with a -garment, and the clouds that in due season drop fatness on the earth, -are alike gendered by the sun; since every movement in our air, from -the health-bringing breeze to the most destructive hurricane, owns him -as its parent; we must at the outset admit, that if there is any body -external to the earth whose varying aspect or condition can inform us -beforehand of changes which the weather is to undergo, the sun is that -body. That for countless ages the moon should have been regarded as -the great weather-breeder, shows only how prone men are to recognize -in apparent changes the true cause of real changes, and how slight -the evidence is on which they will base laws of association which -have no real foundation in fact. Every one can see when the moon is -full, or horned, or gibbous, or half-full; when her horns are directed -upwards, or downwards, or sideways. And as the weather is always -changing, even as the moon is always changing, it must needs happen -that from time to time changes of weather so closely follow changes -of the moon as to suggest that the two orders of change stand to each -other in the relation of cause and effect. Thus rough rules (such as -those which Aratus has handed down to us) came to be formed, and as -(to use Bacon’s expression) men mark when such rules hit, and never -mark when they miss, a system of weather lore gradually comes into -being, which, while in one sense based on facts, has not in reality a -particle of true evidence in its favour—every single fact noted for -each relation having been contradicted by several unnoted facts opposed -to the relation. There could be no more instructive illustration of -men’s habits in such matters than the system of lunar weather wisdom in -vogue to this day among seamen, though long since utterly disproved by -science. But let it be remarked in passing, that in leaving the moon, -which has no direct influence, and scarcely any indirect influence, on -the weather, for the sun, which is all-powerful, we have not got rid of -the mental habits which led men so far astray in former times. We shall -have to be specially careful lest it lead us astray yet once more, -perhaps all the more readily because of the confidence with which we -feel that, at the outset anyway, we are on the right road. - -I suppose there must have been a time when men were not altogether -certain whether the varying apparent path of the sun, as he travels -from east to west every day, has any special effect on the weather. -It seems so natural to us to recognize in the sun’s greater mid-day -elevation and longer continuance above the horizon in summer, the cause -of the greater warmth which then commonly prevails, that we find it -difficult to believe that men could ever have been in doubt on this -subject. Yet it is probable that a long time passed after the position -of the sun as ruler of the day had been noticed, before his power as -ruler of the seasons was recognized. I cannot at this moment recall -any passage in the Bible, for example, in which direct reference is -made to the sun’s special influence in bringing about the seasons, or -any passage in very ancient writings referring definitely to the fact -that the weather changes with the changing position of the sun in the -skies (as distinguished from the star-sphere), and with the changing -length of the day. “While the earth remaineth,” we are told in Genesis, -“seed-time and harvest, and cold and heat, and summer and winter, and -day and night, shall not cease;” but there is no reference to the sun’s -aspect as determining summer and winter. We find no mention of any of -the celestial signs of the seasons anywhere in the Bible, I think, but -such signs as are mentioned in the parable of the fig tree—“When his -branch is yet tender, and putteth forth leaves, ye know that summer is -nigh.” Whether this indicates or not that the terrestrial, rather than -the celestial signs of the progress of the year were chiefly noted by -men in those times, it is tolerably certain that in the beginning a -long interval must have elapsed between the recognition of the seasons -themselves, and the recognition of their origin in the changes of the -sun’s apparent motions. - -When this discovery was effected, men made the most important and, I -think, the most satisfactory step towards the determination of cyclic -associations between solar and terrestrial phenomena. It is for that -reason that I refer specially to the point. In reality, it does not -appertain to my subject, for seasons and sun-spots are not associated. -But it admirably illustrates the value of cyclic relations. Men might -have gone on for centuries, we may conceive, noting the recurrence -of seed-time and harvest-time, summer and winter, recognizing the -periodical returns of heat and cold, and (in some regions) of dry -seasons and wet seasons, of calm and storm, and so forth, without -perceiving that the sun runs through his changes of diurnal motion in -the same cyclic period. We can imagine that some few who might notice -the connection between the two orders of celestial phenomena would -be anxious to spread their faith in the association among their less -observant brethren. They might maintain that observatories for watching -the motions of the sun would demonstrate either that their belief -was just or that it was not so, would in fact dispose finally of the -question. It is giving the most advantageous possible position to those -who now advocate the erection of solar observatories for determining -what connection, if any, may exist between sun-spots and terrestrial -phenomena, thus to compare them to observers who had noted a relation -which unquestionably exists. But it is worthy of notice that if those -whom I have imagined thus urging the erection of an observatory for -solving the question whether the sun rules the seasons, and to some -degree regulates the recurrence of dry or rainy, and of calm or -stormy weather, had promised results of material value from their -observations, they would have promised more than they could possibly -have performed. Even in this most favourable case, where the sun is, -beyond all question, the efficient ruling body, where the nature of -the cyclic change is most exactly determinable, and where even the way -in which the sun acts can be exactly ascertained, no direct benefit -accrues from the knowledge. The exact determination of the sun’s -apparent motions has its value, and this value is great, but it is most -certainly not derived from any power of predicting the recurrence of -those phenomena which nevertheless depend directly on the sun’s action. -The farmer who in any given year knows from the almanac the exact -duration of daylight, and the exact mid-day elevation of the sun for -every day in the year, is not one whit better able to protect his crops -or his herds against storm or flood than the tiller of the soil or the -tender of flocks a hundred thousand years or so ago, who knew only when -seed-time and summer and harvest-time and winter were at hand or in -progress. - -The evidence thus afforded is by no means promising, then, so far as -the prediction of special storms, or floods, or droughts is concerned. -It would seem that if past experience can afford any evidence in such -matters, men may expect to recognize cycles of weather change long -before they recognize corresponding solar cycles (presuming always that -such cycles exist), and that they may expect to find the recognition -of such association utterly barren, so far as the possibility of -predicting definite weather changes is concerned. It would seem that -there is no likelihood of anything better than what Sir J. Herschel -said _might_ be hoped for hereafter. “A lucky hit may be made; nay, -some rude approach to the perception of a ‘cycle of seasons’ may -_possibly_ be obtainable. But no person in his senses would alter -his plans of conduct for six months in advance in the most trifling -particular on the faith of any special prediction of a warm or a cold, -a wet or a dry, a calm or a stormy, summer or winter”—far less of a -great storm or flood announced for any special day. - -But let us see what the cycle association between solar spots and -terrestrial weather actually is, or rather of what nature it promises -to be, for as yet the true nature of the association has not been made -out. - -It has been found that in a period of about eleven years the sun’s -surface is affected by what may be described as a wave of sun-spots. -There is a short time—a year or so—during which scarce any spots are -seen; they become more and more numerous during the next four or five -years, until they attain a maximum of frequency and size; after this -they wane in number and dimensions, until at length, about eleven years -from the time when he had before been freest from spots, he attains -again a similar condition. After this the spots begin to return, -gradually attain to a maximum, then gradually diminish, until after -eleven more years have elapsed few or none are seen. It must not be -supposed that the sun is always free from spots at the time of minimum -spot frequency, or that he always shows many and large spots at the -time of maximum spot frequency. Occasionally several very large spots, -and sometimes singularly large spots, have been seen in the very heart -of the minimum spot season, and again there have been occasions when -scarcely any spots have been seen for several days in the very heart -of the maximum spot season. But, taking the average of each year, -the progression of the spots in number and frequency from minimum -to maximum, and their decline from maximum to minimum, are quite -unmistakeable. - -Now there are some terrestrial phenomena which we might expect to -respond in greater or less degree to the sun’s changes of condition -with respect to spots. We cannot doubt that the emission both of light -and of heat is affected by the presence of spots. It is not altogether -clear in what way the emission is affected. We cannot at once assume -that because the spots are dark the quantity of sunlight must be less -when the spots are numerous; for it may well be that the rest of the -sun’s surface may at such times be notably brighter than usual, and the -total emission of light may be greater on the whole instead of less. -Similarly of the emission of heat. It is certain that when there are -many spots the surface of the sun is far less uniform in brightness -than at other times. The increase of brightness all round the spots is -obvious to the eye when the sun’s image, duly enlarged, is received -upon a screen in a darkened room. Whether the total emission of light -is increased or diminished has not yet been put to the test. Professor -Langley, of the Alleghany Observatory, near Pittsburg, U.S., has -carefully measured the diminution of the sun’s emission of light and -heat on the assumption that the portion of the surface not marked by -spots remains unchanged in lustre. But until the total emission of -light and heat at the times of maximum and minimum has been measured, -without any assumption of the kind, we cannot decide the question. - -More satisfactory would seem to be the measurements which have been -made by Professor Piazzi Smyth, at Edinburgh, and later by the -Astronomer Royal at Greenwich, into the underground temperature of -the earth. By examining the temperature deep down below the surface, -all local and temporary causes of change are eliminated, and causes -external to the earth can alone be regarded as effective in producing -systematic changes. “The effect is very slight,” I wrote a few years -ago, “indeed barely recognizable. I have before me as I write Professor -Smyth’s sheet of the quarterly temperatures from 1837 to 1869 at -depths of 3, 6, 12, and 24 French feet. Of course the most remarkable -feature, even at the depth of 24 feet, is the alternate rise and fall -with the seasons. But it is seen that, while the range of rise and fall -remains very nearly constant, the crests and troughs of the waves lie -at varying levels.” After describing in the essay above referred to, -which appears in my “Science Byways,” the actual configuration of the -curves of temperature both for seasons and for years, and the chart in -which the sun-spot waves and the temperature waves are brought into -comparison, I was obliged to admit that the alleged association between -the sun-spot period and the changes of underground temperature did -not seem to me very clearly made out. It appears, however, there is a -slight increase of temperature at the time when the sun-spots are least -numerous. - -That the earth’s magnetism is affected by the sun’s condition with -respect to spots, seems to have been more clearly made out, though -it must be noted that the Astronomer Royal considers the Greenwich -magnetic observations inconsistent with this theory. It seems to have -been rendered at least extremely probable that the daily oscillation -of the magnetic needle is greater when spots are numerous than when -there are few spots or none. Magnetic storms are also more numerous at -the time of maximum spot-frequency, and auroras are then more common. -(The reader will not fall into the mistake of supposing that magnetic -storms have the remotest resemblance to hurricanes, or rainstorms, or -hailstorms, or even to thunderstorms, though the thunderstorm is an -electrical phenomenon. What is meant by a magnetic storm is simply such -a condition of the earth’s frame that the magnetic currents traversing -it are unusually strong.) - -Thus far, however, we have merely considered relations which we might -fairly expect to find affected by the sun’s condition as to spots. -A slight change in his total brightness and in the total amount of -heat emitted by him may naturally be looked for under circumstances -which visibly affect the emission of light, and presumably affect the -emission of heat also, from portions of his surface. Nor can we wonder -if terrestrial magnetism, which is directly dependent on the sun’s -emission of heat, should be affected by the existence of spots upon his -surface. - -It is otherwise with the effects which have recently been associated -with the sun’s condition. It may or may not prove actually to be the -case that wind and rain vary in quantity as the sun-spots vary in -number (at least when we take in both cases the average for a year, or -for two or three years), but it cannot be said that any such relation -was antecedently to be expected. When we consider what the sun actually -does for our earth, it seems unlikely that special effects such as -these should depend on relatively minute peculiarities of the sun’s -surface. There is our earth, with her oceans and continents, turning -around swiftly on her axis, and exposed to his rays as a whole. Or, -inverting the way of viewing matters, there is the sun riding high in -the heavens of any region of the earth, pouring down his rays upon that -region. We can understand how in the one case that rotating orb of the -earth may receive rather more or rather less heat from the sun when -he is spotted than when he is not, or how in the other way of viewing -matters, that orb of the sun may give to any region rather more or -rather less heat according as his surface is more or less spotted. -But that in special regions of that rotating earth storms should be -more or less frequent or rainfall heavier or lighter, as the sun’s -condition changes through the exceedingly small range of variation due -to the formation of spots, seems antecedently altogether unlikely; and -equally unlikely the idea that peculiarities affecting limited regions -of the sun’s surface should affect appreciably the general condition -of the earth. If a somewhat homely comparison may be permitted, we -can well understand how a piece of meat roasting before a fire may -receive a greater or less supply of heat on the whole as the fire -undergoes slight local changes (very slight indeed they must be, that -the illustration may be accurate); but it would be extremely surprising -if, in consequence of such slight changes in the fire, the roasting of -particular portions of the joint were markedly accelerated or delayed, -or affected in any other special manner. - -But of course all such considerations as to antecedent probabilities -must give way before the actual evidence of observed facts. Utterly -inconsistent with all that is yet known of the sun’s physical action, -as it may seem, on _à priori_ grounds, to suppose that spots, currents, -or other local disturbances of the sun’s surface could produce any but -general effects on the earth as a whole, yet if we shall find that -particular effects are produced in special regions of the earth’s -surface in cycles unmistakably synchronizing with the solar-spot-cycle, -we must accept the fact, whether we can explain it or not. Only let it -be remembered at the outset that the earth is a large place, and the -variations of wind and calm, rain and drought, are many and various in -different regions. Whatever place we select for examining the rainfall, -for example, we are likely to find, in running over the records of the -last thirty years or so, some seemingly oscillatory changes; in the -records of the winds, again, we are likely to find other seemingly -oscillatory changes; if none of these records provide anything which -seems in any way to correspond with the solar spot-cycle, we may -perchance find some such cycle in the relative rainfall of particular -months, or in the varying wetness or dryness of particular winds, and -so forth. Or, if we utterly fail to find any such relation in one -place we may find it in another, or not improbably in half-a-dozen -places among the hundreds which are available for the search. If we -are content with imperfect correspondence between some meteorological -process or another and the solar-spot cycle, we shall be exceedingly -unfortunate indeed if we fail to find a score of illustrative -instances. And if we only record these, without noticing any of the -cases where we fail to find any association whatever—in other words, -as Bacon puts it, if “we note when we hit and never note when we -miss,” we shall be able to make what will seem a very strong case -indeed. But this is not exactly the scientific method in such cases. -By following such a course, indeed, we might prove almost anything. If -we take, for instance, a pack of cards, and regard the cards in order -as corresponding to the years 1825 to 1877, and note their colours as -dealt _once_, we shall find it very difficult to show that there is any -connection whatever between the colours of the cards corresponding to -particular years and the number of spots on the sun’s face. But if we -repeat the process a thousand times, we shall find certain instances -among the number, in which red suits correspond to all the years when -there are many spots on the sun, and black suits to all the years -when there are few spots on the sun. If now we were to publish all -such deals, without mentioning anything at all about the others which -showed no such association, we should go far to convince a certain -section of the public that the condition of the sun as to spots might -hereafter be foretold by the cards; whence, if the public were already -satisfied that the condition of the sun specially affects the weather -of particular places, it would follow that the future weather of these -places might also be foretold by the cards. - -I mention this matter at the outset, because many who are anxious to -find some such cycle of seasons as Sir John Herschel thought might be -discovered, have somewhat overlooked the fact that we must not hunt -down such a cycle _per fas et nefas_. “Surely in meteorology as in -astronomy,” Mr. Lockyer writes, for instance, “the thing to hunt down -is a cycle, and if that is not to be found in the temperate zone, then -go to the frigid zones or the torrid zone to look for it; and if found, -then above all things and in whatever manner, lay hold of, study, and -read it, and see what it means.” There can be no doubt that this is the -way to find a cycle, or at least to find what looks like a cycle, but -the worth of a cycle found in this way will be very questionable.[7] - -I would not have it understood, however, that I consider all the cycles -now to be referred to as unreal, or even that the supposed connection -between them and the solar cycle has no existence. I only note that -there are thousands, if not tens of thousands, of relations among -which cycles may be looked for, and that there are perhaps twenty or -thirty cases in which some sort of cyclic association between certain -meteorological relations and the period of the solar spots presents -itself. According to the recognized laws of probability, some at least -amongst these cases must be regarded as accidental. Some, however, may -still remain which are not accidental. - -Among the earliest published instances may be mentioned Mr. Baxendell’s -recognition of the fact that during a certain series of years, about -thirty, I think, the amount of rainfall at Oxford was greater under -west and south-west winds than under south and south-east winds when -sun-spots were most numerous, whereas the reverse held in years when -there were no spots or few. Examining the meteorological records of -St. Petersburg, he found that a contrary state of things prevailed -there. - -The Rev. Mr. Main, Director of the Radcliffe Observatory at Oxford, -found that westerly winds were slightly more common (as compared with -other winds) when sun-spots were numerous than when they were few. - -Mr. Meldrum, of Mauritius, has made a series of statistical inquiries -into the records of cyclones which have traversed the Indian Ocean -between the equator and 34 degrees south latitude, in each year from -1856 to 1877, noting the total distances traversed by each, the sums -of their radii and areas, their duration in days, the sums of their -total areas, and their relative areas. His researches, be it marked -in passing, are of extreme interest and value, whether the suggested -connection between sun-spots and cyclones (in the region specified) -be eventually found to be a real one or not. The following are his -results, as described in _Nature_ by a writer who manifestly favours -very strongly the doctrine that an intimate association exists between -solar maculation (or spottiness) and terrestrial meteorological -phenomena:— - -“The period embraces two complete, or all but complete, sun-spot -periods, the former beginning with 1856 and ending in 1867, and the -latter extending from 1867 to about the present time [1877]. The broad -result is that the number of cyclones, the length and duration of -their courses, and the extent of the earth’s surface covered by them -all, reach the maximum in each sun-spot period during the years of -maximum maculation, and fall to the minimum during the years of minimum -maculation. The peculiar value of these results lies in the fact that -the portion of the earth’s surface over which this investigation -extends, is, from its geographical position and what may be termed -its meteorological homogeneity, singularly well fitted to bring out -prominently any connection that may exist between the condition of the -sun’s surface and atmospheric phenomena.” - -The writer proceeds to describe an instance in which Mr. Meldrum -predicted future meteorological phenomena, though without specifying -the exact extent to which Mr. Meldrum’s anticipations were fulfilled or -the reverse. “A drought commenced in Mauritius early in November,” he -says, “and Mr. Meldrum ventured (on December 21) to express publicly -his opinion that probably the drought would not break up till towards -the end of January, and that it might last till the middle of February, -adding that up to these dates the rainfall of the island would probably -not exceed 50 per cent. of the mean fall. This opinion was an inference -grounded on past observations, which show that former droughts have -lasted from about three to three and a half months, and that these -droughts have occurred in the years of minimum sun-spots, or, at all -events, in years when the spots were far below the average, such as -1842, 1843, 1855, 1856, 1864, 1866, and 1867, and that now we are -near the minimum epoch of sun-spots. It was further stated that the -probability of rains being brought earlier by a cyclone was but slight, -seeing that the season for cyclones is not till February or March, and -that no cyclone whatever visited Mauritius during 1853–56 and 1864–67, -the years of minimum sun-spots. From the immense practical importance -of this application of the connection between sun-spots and weather -to the prediction of the character of the weather of the ensuing -season, we shall look forward with the liveliest interest to a detailed -statement of the weather which actually occurred in that part of the -Indian Ocean from November to March last [1876].” - -It was natural that the great Indian famine, occurring at a time -when sun-spots were nearly at a minimum, should by some be directly -associated with a deficiency of sun-spots. In this country, indeed, -we have had little reason, during the last two or three years of few -sun-spots, to consider that drought is one of the special consequences -to be attributed to deficient solar maculation. But in India it may -be different, or at least it may be different in Madras, for it has -been satisfactorily proved that in some parts of India the rainfall -increases in inverse, not in direct proportion, to the extent of -solar maculation. Dr. Hunter has shown to the satisfaction of many -that at Madras there is “a cycle of rainfall corresponding with the -period of solar maculation.” But Mr. E. D. Archibald, who is also -thoroughly satisfied that the sun-spots affect the weather, remarks -that Dr. Hunter has been somewhat hasty in arguing that the same -conditions apply throughout the whole of Southern India. “This hasty -generalization from the results of one station situated in a vast -continent, the rainfall of which varies completely, both in amount and -the season in which it falls, according to locality, has been strongly -contested by Mr. Blanford, the Government Meteorologist, who, in making -a careful comparison of the rainfalls of seven stations, three of which -(Madras, Bangalore, and Mysore) are in Southern India, the others -being Bombay, Najpore, Jubbulpore, and Calcutta, finds that, with the -exception of Najpore in Central India, which shows some slight approach -to the same cyclical variation which is so distinctly marked in the -Madras registers, the rest of the stations form complete exceptions -to the rule adduced for Madras, in many of them the hypothetical -order of relation being reversed. Mr. Blanford, however, shows that, -underlying the above irregularities, a certain cyclical variation -exists on the average at all the stations, the amount, nevertheless, -being so insignificant (not more than 9 per cent. of the total falls) -that it could not be considered of sufficient magnitude to become a -direct factor in the production of famine. It thus appears that the -cycle of rainfall which is considered to be the most important element -in causing periodic famines has only been proved satisfactorily for -the town of Madras. It may perhaps hold for the Carnatic and Northern -Siccars, the country immediately surrounding Madras, though perhaps, -owing to the want of rainfall registers in these districts, evidence -with regard to this part is still wanting.” On this Mr. Archibald -proceeds to remark that, though Dr. Hunter has been only partially -successful, the value of his able pamphlet is not diminished in any -way, “an indirect effect of which has been to stimulate meteorological -inquiry and research in the same direction throughout India. The -meteorology of this country (India), from its peculiar and tropical -position, is in such complete unison with any changes that may -arise from oscillations in the amount of solar radiation, and their -effects upon the velocity and direction of the vapour-bearing winds, -that a careful study of it cannot fail to discover meteorological -periodicities in close connection with corresponding periods of solar -disturbance.” So, indeed, it would seem. - -The hope that famines may be abated, or, at least, some of their most -grievous consequences forestalled by means of solar observatories, does -not appear very clearly made out. Rather it would seem that the proper -thing to do is to investigate the meteorological records of different -Indian regions, and consider the resulting evidence of cyclic changes -without any special reference to sun-spots; for if sun-spots may cause -drought in one place, heavy rainfall in another, winds here and calms -there, it seems conceivable that the effects of sun-spots may differ at -different times, as they manifestly do in different places. - -Let us turn, however, from famines to shipwrecks. Perhaps, if we admit -that cyclones are more numerous, and blow more fiercely, and range -more widely, even though it be over one large oceanic region only, in -the sun-spot seasons than at other times, we may be assured, without -further research, that shipwrecks will, on the whole, be more numerous -near the time of sun-spot maxima than near the time of sun-spot minima. - -The idea that this may be so was vaguely shadowed forth in a poem of -many stanzas, called “The Meteorology of the Future: a Vision,” which -appeared in _Nature_ for July 5, 1877. I do not profess to understand -precisely what the object of this poem may have been-—I mean, whether -it is intended to support or not the theory that sun-spots influence -the weather. Several stanzas are very humorous, but the object of the -humour is not manifest. The part referred to above is as follows:—Poor -Jack lies at the bottom of the sea in 1881, and is asked in a spiritual -way various questions as to the cause of his thus coming to grief. This -he attributed to the rottenness of the ship in which he sailed, to -the jobbery of the inspector, to the failure of the system of weather -telegraphing, and so forth. But, says the questioner, there was one - - “In fame to none will yield, - He led the band who reaped renown - On India’s famine field. - - “Was he the man to see thee die? - Thou wilt not tax him—come? - The dead man groaned—‘_I met my death - Through a sun-spot maximum_.’” - -The first definite enunciation, however, of a relation between -sun-spots and shipwrecks appeared in September, 1876. Mr. Henry -Jeula, in the _Times_ for September 19, stated that Dr. Hunter’s -researches into the Madras rainfall had led him to throw together the -scanty materials available relating to losses posted on Lloyd’s loss -book, to ascertain if any coincidences existed between the varying -number of such losses and Dr. Hunter’s results. “For,” he proceeds, -“since the cycle of rainfall at Madras coincides, I am informed, with -the periodicity of the cyclones in the adjoining Bay of Bengal” (a -relation which is more than doubtful) “as worked out by the Government -Astronomer at Mauritius” (whose researches, however, as we have seen, -related to a region remote from the Bay of Bengal), “some coincidence -between maritime casualties, rainfalls, and sun-spots appeared at -least possible.” In passing, I may note that if any such relation were -established, it would be only an extension of the significance of -the cycle of cyclones, and could have no independent value. It would -certainly follow, if the cycle of cyclones is made out, that shipwrecks -being more numerous, merchants would suffer, and we should have the -influence of the solar spots asserting itself in the _Gazette_. From -the cyclic derangement of monetary and mercantile matters, again, -other relations also cyclic in character would arise. But as all these -may be inferred from the cycle of cyclones once this is established, -we could scarcely find in their occurrence fresh evidence of the -necessity of that much begged-for solar observatory. The last great -monetary panic in this country, by the way, occurred in 1866, at a -time of minimum solar maculation. Have we here a decisive proof that -the sun rules the money market, the bank rate of discount rising to a -maximum as the sun-spots sink to a minimum, and _vice versâ_? The idea -is strengthened by the fact that the American panic in 1873 occurred -when spots were very numerous, and its effects have steadily subsided -as the spots have diminished in number; for this shows that the sun -rules the money market in America on a principle diametrically opposed -to that on which he (manifestly) rules the money market in England, -precisely as the spots cause drought in Calcutta and plenteous rainfall -at Madras, wet south-westers and dry south-westers at Oxford, and wet -south-easters and dry south-easters at St. Petersburg. Surely it would -be unreasonable to refuse to recognize the weight of evidence which -thus tells on both sides at once. - -To return, however, to the sun’s influence upon shipwrecks. - -Mr. Jeula was “only able to obtain data for two complete cycles of -eleven years, namely, from 1855 to 1876 inclusive, while the period -investigated by Dr. Hunter extended from 1813 to 1876, and his -observations related to Madras and its neighbourhood only, while the -losses posted at Lloyd’s occurred to vessels of various countries, and -happened in different parts of the world. It was necessary to bring -these losses to some common basis of comparison, and the only available -one was the number of ‘British registered vessels of the United Kingdom -and Channel Islands’—manifestly an arbitrary one. I consequently -cast out the percentage of losses posted each year upon the number of -registered vessels for the same year, and also the percentage of losses -posted in each of the eleven years of the two cycles upon the total -posted in each complete cycle, thus obtaining two bases of comparison -independent of each other.” - -The results may be thus presented:— - -Taking the four years of each cycle when sun-spots were least in -number, Mr. Jeula found the mean percentage of losses in registered -vessels of the United Kingdom and Channel Islands to be 11·13, and the -mean percentage of losses in the total posted in the entire cycle of -eleven years to be 8·64. - -In the four years when sun-spots were intermediate in number, that -is in two years following the minimum and in two years preceding the -minimum, the respective percentages were 11·91 and 9·21. - -Lastly, in the three years when sun-spots were most numerous, these -percentages were, respectively, 12·49 and 9·53. - -That the reader may more clearly understand what is meant here by -percentages, I explain that while the numbers 11·13, 11·91 and 12·49 -simply indicate the average number of wrecks (per hundred of all -the ships registered) which occurred in the several years of the -eleven-years cycle, the other numbers, 8·64, 19·21, and 9·53, indicate -the average number of wrecks (per hundred of wrecks recorded) during -eleven successive years, which occurred in the several years of the -cycle. The latter numbers seem more directly to the purpose; and as the -two sets agree pretty closely, we may limit our attention to them. - -Now I would in the first place point out that it would have been well -if the actual number or percentage had been indicated for each year of -the cycle, instead of for periods of four years, four years, and three -years. Two eleven-year cycles give in any case but meagre evidence, -and it would have been well if the evidence had been given as fully -as possible. If we had a hundred eleven-yearly cycles, and took the -averages of wrecks for the four years of minimum solar maculation, the -four intermediate years, and the three years of maximum maculation, -we might rely with considerable confidence on the result, because -accidental peculiarities one way or the other could be eliminated. But -in two cycles only, such peculiarities may entirely mask any cyclic -relation really existing, and appear to indicate a relation which has -no real existence. If the percentages had been given for each year, -the effect of such peculiarities would doubtless still remain, and the -final result would not be more trustworthy than before; but we should -have a chance of deciding whether such peculiarities really exist or -not, and also of determining what their nature may be. As an instance -in point, let me cite a case where, having only the results of a -single cycle, we can so arrange them as to appear to indicate a cyclic -association between sun-spots and rainfall, while, when we give them -year by year, such an association is discredited, to say the least. - -The total rainfall at Port Louis, between the years 1855 and 1868 -inclusive, is as follows:— - - In _Rainfall._ _Condition of Sun._ - 1855 42·665 inches Sun-spot minimum. - 1856 46·230 „ - 1857 43·445 „ - 1858 35·506 „ - 1859 56·875 „ - 1860 45·166 „ Sun-spot maximum. - 1861 68·733 „ - 1862 28·397 „ - 1863 33·420 „ - 1864 24·147 „ - 1865 44·730 „ - 1866 20·571 „ Sun-spot minimum. - 1867 35·970 „ - 1868 64·180 „ - -[Illustration] - -I think no one, looking at these numbers as they stand, can recognize -any evidence of a cyclic tendency. If we represent the rainfall by -ordinates we get the accompanying figure, which shows the rainfall for -eighteen years, and again I think it may be said that a very lively -imagination is required to recognize anything resembling that wave-like -undulation which the fundamental law of statistics requires where -a cycle is to be made out from a single oscillation. Certainly the -agreement between the broken curve of rainfall and the sun-spot curve -indicated by the waved dotted line is not glaringly obvious. But when -we strike an average for the rainfall, in the way adopted by Mr. Jeula -for shipwrecks, how pleasantly is the theory of sun-spot influence -illustrated by the Port Louis rainfall! Here is the result, as quoted -by the high-priest of the new order of diviners, from the papers by Mr. -Meldrum:— - - Three minimum years—total rainfall 133·340 - Three maximum years—total rainfall 170·774 - Three minimum years—total rainfall 120·721 - -Nothing could be more satisfactory, but nothing, I venture to assert, -more thoroughly inconsistent with the true method of statistical -research. - -May it not be that, underlying the broad results presented by Mr. -Jeula, there are similar irregularities? - -When we consider that the loss of ships depends, not only on a cause so -irregularly variable (to all seeming) as wind-storms, but also on other -matters liable to constant change, as the variations in the state of -trade, the occurrence of wars and rumours of wars, special events, such -as international exhibitions, and so forth, we perceive that an even -wider range of survey is required to remove the effects of accidental -peculiarities in their case, than in the case of rainfall, cyclones, -or the like. I cannot but think, for instance, that the total number -of ships lost in divers ways during the American war, and especially -in its earlier years (corresponding with two of the three maximum -years of sun-spots) may have been greater, not merely absolutely but -relatively, than in other years. I think it conceivable, again, that -during the depression following the great commercial panic of 1866 -(occurring at a time of minimum solar maculation, as already noticed) -the loss of ships may have been to some degree reduced, relatively as -well as absolutely. We know that when trade is unusually active many -ships have sailed, and perhaps may still be allowed to sail (despite -Mr. Plimsoll’s endeavours), which should have been broken up; whereas -in times of trade depression the ships actually afloat are likely -to be, _on the average_, of a better class. So also, when, for some -special reason, passenger traffic at sea is abnormally increased. I -merely mention these as illustrative cases of causes not (probably) -dependent on sun-spots, which may (not improbably) have affected the -results examined by Mr. Jeula. I think it possible that those results, -if presented for each year, would have indicated the operation of such -causes, naturally masked when sets of four years, four years, and three -years are taken instead of single years. - -I imagine that considerations such as these will have to be taken into -account and disposed of before it will be unhesitatingly admitted that -sun-spots have any great effect in increasing the number of shipwrecks. - -The advocates of the doctrine of sun-spot influence—or, perhaps -it would be more correct to say, the advocates of the endowment of -sun-spot research—think differently on these and other points. Each -one of the somewhat doubtful relations discussed above is constantly -referred to by them as a demonstrated fact, and a demonstrative proof -of the theory they advocate. For instance, Mr. Lockyer, in referring to -Meldrum’s statistical researches into the frequency of cyclones, does -not hesitate to assert that according to these researches “the whole -question of cyclones is merely a question of solar activity, and that -if we wrote down in one column the number of cyclones in any given -year, and in another column the number of sun-spots in any given year, -there will be a strict relation between them—many sun-spots, many -hurricanes; few sun-spots, few hurricanes.” ... And again, “Mr. Meldrum -has since found” (not merely “has since found reason to believe,” but -definitely, “has since found”) “that what is true of the storms which -devastate the Indian Ocean is true of the storms which devastate the -West Indies; and on referring to the storms of the Indian Ocean, Mr. -Meldrum points out that at those years where we have been quietly -mapping the sun-spot maxima, the harbours were filled with wrecks, and -vessels coming in disabled from every part of the Indian Ocean.” Again, -Mr. Balfour Stewart accepts Mr. Jeula’s statistics confidently as -demonstrating that there are most shipwrecks during periods of maximum -solar activity. Nor are the advocates of the new method of prediction -at all doubtful as to the value of these relations in affording the -basis of a system of prediction. They do not tell us precisely _how_ we -are to profit by the fact, if fact it is, that cyclones and shipwrecks -mark the time of maximum solar maculation, and droughts and famine the -time of minimum. “If we can manage to get at these things,” says Mr. -Lockyer, “the power of prediction, that power which would be the most -useful one in meteorology, if we could only get at it, would be within -our grasp.” And Mr. Balfour Stewart, in a letter to the _Times_, says, -“If we are on the track of a discovery which will in time enable -us to foretell the cycle of droughts, public opinion should demand -that the investigation be prosecuted with redoubled vigour and under -better conditions. If forewarned be forearmed, then such research will -ultimately conduce to the saving of life both at times of maximum and -minimum sun-spot frequency.” - -If these hopes are really justified by the facts of the case, it would -be well that the matter should be as quickly as possible put to the -test. No one would be so heartless, I think, as to reject, through an -excess of scientific caution, a scheme which might issue in the saving -of many lives from famine or from shipwreck. And on the other hand, no -one, I think, would believe so ill of his fellow-men as to suppose for -one moment that advantage could be taken of the sympathies which have -been aroused by the Indian famine, or which may from time to time be -excited by the record of great disasters by sea and land, to advocate -bottomless schemes merely for purposes of personal advancement. We must -now, perforce, believe that those who advocate the erection of new -observatories and laboratories for studying the physics of the sun, -have the most thorough faith in the scheme which they proffer to save -our Indian population from famine and our seamen from shipwreck. - -But they, on the other hand, should now also believe that those who -have described the scheme as entirely hopeless, do really so regard it. -If we exonerate them from the charge of responding to an appeal for -food by offering spectroscopes, they in turn should exonerate us from -the charge of denying spectroscopes to the starving millions of India -though knowing well that the spectroscopic track leads straight to -safety. - -I must acknowledge I cannot for my own part see even that small modicum -of hope in the course suggested which would suffice to justify its -being followed. In my opinion, one ounce of rice would be worth more -(simply because it would be worth something) than ten thousand tons of -spectroscopes. For what, in the first place, has been shown as to the -connection between meteorological phenomena and sun-spots? Supposing we -grant, and it is granting a great deal, that all the cycles referred -to have been made out. They one and all affect averages only. The most -marked among them can so little be trusted in detail that while the -maximum of sun-spots agrees _in the main_ with an excess or defect of -rain or wind, or of special rains with special winds, or the like, the -actual year of maximum may present the exact reverse. - -Of what use can it be to know, for instance, that the three years of -least solar maculation will probably give a rainfall less than that -for the preceding or following three years, if the middle year of -the three, when the spots are most numerous of all, _may_ haply show -plenteous rainfall? Or it may be the first of the three, or the last, -which is thus well supplied, while a defect in the other two, or in one -of the others, brings the total triennial rainfall below the average. -What provision could possibly be made under such circumstances to meet -a contingency which may occur in any one of three years? or, at least, -what provision could be made which would prove nearly so effective -as an arrangement which could readily be made for keeping sufficient -Government stores at suitable stations (that is, never allowing such -stores to fall at the critical season in each year below a certain -minimum), and sending early telegraphic information of unfavourable -weather? Does any one suppose that the solar rice-grains are better -worth watching for such a purpose than the terrestrial rice-grains, or -that it is not well within the resources of modern science and modern -means of communication and transport, to make sufficient preparation -each year for a calamity always possible in India? And be it noticed -that if, on the one hand, believers in solar safety from famine may -urge that, in thus objecting to their scheme, I am opposing what might, -in some year of great famine and small sun-spots, save the lives of -a greater number than would be saved by any system of terrestrial -watchfulness, I would point out, on the other, that the solar scheme, -if it means anything at all, means special watchfulness at the minimum -sun-spot season, and general confidence (so far as famine is concerned) -at the season of maximum solar maculation; and that while as yet -nothing has been really proved about the connection between sun-spots -and famine, such confidence might prove to be a very dangerous mistake. - -Supposing even it were not only proved that sun-spots exert such and -such effects, but that this knowledge can avail to help us to measures -of special precaution, how is the study of the sun going to advance -our knowledge? In passing, let it be remarked that already an enormous -number of workers are engaged in studying the sun in every part of -the world. The sun is watched on every fine day, in every quarter of -the earth, with the telescope, analyzed with the spectroscope, his -prominences counted and measured, his surface photographed, and so -forth. What more ought to be or could be done? But that is not the main -point. If more could be done, what could be added to our knowledge -which would avail in the way of prediction? “At present,” says Mr. -Balfour Stewart, “the problem has not been pursued on a sufficiently -large scale or in a sufficient number of places. If the attack is to -be continued, the skirmishers should give way to heavy guns, and these -should be brought to bear without delay now that the point of attack is -known.” In other words, now that we know, according to the advocates -of these views, that meteorological phenomena follow roughly the great -solar-spot period, we should prosecute the attack in this direction, -in order to find out—what? Minor periods, perhaps, with which -meteorological phenomena may still more roughly synchronize. Other such -periods are already known with which meteorological phenomena have -never yet been associated. New details of the sun’s surface? No one has -yet pretended that any of the details already known, except the spots, -affect terrestrial weather, and the idea that peculiarities so minute -as hitherto to have escaped detection can do so, is as absurd, on the -face of it, as the supposition that minute details in the structure -of a burning coal, such details as could only be detected by close -scrutiny, can affect the general quality and effects of the heat -transmitted by the coal, as part of a large fire, to the further side -of a large room. - -Lastly, I would urge this general argument against a theory which seems -to me to have even less to recommend it to acceptance than the faith -in astrology.[8] _If it requires, as we are so strongly assured, the -most costly observations, the employment of the heaviest guns (and -“great guns” are generally expensive), twenty or thirty years of time, -and the closest scrutiny and research, to prove that sun-spots affect -terrestrial relations in a definite manner, effects so extremely -difficult to demonstrate cannot possibly be important enough to be -worth predicting._ - - - - -_NEW WAYS OF MEASURING THE SUN’S DISTANCE._ - - -It is strange that the problem of determining the sun’s distance, which -for many ages was regarded as altogether insoluble, and which even -during later years had seemed fairly solvable in but one or two ways, -should be found, on closer investigation, to admit of many methods -of solution. If astronomers should only be as fortunate hereafter in -dealing with the problem of determining the distances of the stars, -as they have been with the question of the sun’s distance, we may -hope for knowledge respecting the structure of the universe such as -even the Herschels despaired of our ever gaining. Yet this problem of -determining star-distances does not seem more intractable, now, than -the problem of measuring the sun’s distance appeared only two centuries -ago. If we rightly view the many methods devised for dealing with the -easier task, we must admit that the more difficult—which, by the way, -is in reality infinitely the more interesting—cannot be regarded -as so utterly hopeless as, with our present methods and appliances, -it appears to be. True, we know only the distances of two or three -stars, approximately, and have means of forming a vague opinion -about the distances of only a dozen others, or thereabouts, while at -distances now immeasurable lie six thousand stars visible to the eye, -and twenty millions within range of the telescope. Yet, in Galileo’s -time, men might have argued similarly against all hope of measuring -the proportions of the solar system. “We know only,” they might have -urged, “the distance of the moon, our immediate neighbour,—beyond -her, at distances so great that hers, so far as we can judge, is by -comparison almost as nothing, lie the Sun and Mercury, Venus and Mars; -further away yet lie Jupiter and Saturn, and possibly other planets, -not visible to the naked eye, but within range of that wonderful -instrument, the telescope, which our Galileo and others are using so -successfully. What hope can there be, when the exact measurement of the -moon’s distance has so fully taxed our powers of celestial measurement, -that we can ever obtain exact information respecting the distances of -the sun and planets? By what method is a problem so stupendous to be -attacked?” Yet, within a few years of that time, Kepler had formed -already a rough estimate of the distance of the sun; in 1639, young -Horrocks pointed to a method which has since been successfully applied. -Before the end of the seventeenth century Cassini and Flamsteed had -approached the solution of the problem more nearly, while Hailey had -definitely formulated the method which bears his name. Long before the -end of the eighteenth century it was certainly known that the sun’s -distance lies between 85 millions of miles and 98 millions (Kepler, -Cassini, and Flamsteed had been unable to indicate any superior limit). -And lastly, in our own time, half a score of methods, each subdivisible -into several forms, have been applied to the solution of this -fundamental problem of observational astronomy. - -I propose now to sketch some new and very promising methods, which have -been applied already with a degree of success arguing well for the -prospects of future applications of the methods under more favourable -conditions. - -In the first place, let us very briefly consider the methods which had -been before employed, in order that the proper position of the new -methods may be more clearly recognized. - -The plan obviously suggested at the outset for the solution of the -problem was simply to deal with it as a problem of surveying. It was -in such a manner that the moon’s distance had been found, and the -only difficulty in applying the method to the sun or to any planet -consisted in the delicacy of the observations required. The earth being -the only surveying-ground available to astronomers in dealing with -this problem (in dealing with the problem of the stars’ distances they -have a very much wider field of operations), it was necessary that -a base-line should be measured on this globe of ours,—large enough -compared with our small selves, but utterly insignificant compared -with the dimensions of the solar system. The diameter of the earth -being less than 8000 miles, the longest line which the observers could -take for base scarcely exceeded 6000 miles; since observations of the -same celestial object at opposite ends of a diameter necessarily imply -that the object is in the horizon of _both_ the observing stations -(for precisely the same reason that two cords stretched from the ends -of any diameter of a ball to a distant point touch the ball at those -ends). But the sun’s distance being some 92 millions of miles, a base -of 6000 miles amounts to less than the 15,000th part of the distance -to be measured. Conceive a surveyor endeavouring to determine the -distance of a steeple or rock 15,000 feet, or nearly three miles, from -him, with a base-line _one foot_ in length, and you can conceive the -task of astronomers who should attempt to apply the direct surveying -method to determine the sun’s distance,—at least, you have one of -their difficulties strikingly illustrated, though a number of others -remain which the illustration does not indicate. For, after all, a -base one foot in length, though far too short, is a convenient one in -many respects: the observer can pass from one end to the other without -trouble—he looks at the distant object under almost exactly the same -conditions from each end, and so forth. A base 6000 miles long for -determining the sun’s distance is too short in precisely the same -degree, but it is assuredly not so convenient a base for the observer. -A giant 36,000 miles high would find it as convenient as a surveyor -six feet high would find a one foot base-line; but astronomers, as -a rule, are less than 36,000 miles in height. Accordingly the same -observer cannot work at both ends of the base-line, and they have to -send out expeditions to occupy each station. All the circumstances -of temperature, atmosphere, personal observing qualities, etc., are -unlike at the two ends of the base-line. The task of measuring the -sun’s distance directly is, in fact, at present beyond the power of -observational astronomy, wonderfully though its methods have developed -in accuracy. - -We all know how, by observations of Venus in transit, the difficulty -has been so far reduced that trustworthy results have been obtained. -Such observations belong to the surveying method, only Venus’s distance -is made the object of measurement instead of the sun’s. The sun serves -simply as a sort of dial-plate, Venus’s position while in transit -across this celestial dial-plate being more easily measured than when -she is at large upon the sky. The devices by which Halley and Delisle -severally caused _time_ to be the relation observed, instead of -position, do not affect the general principle of the transit method. It -remains dependent on the determination of position. Precisely as by the -change of the _position_ of the hands of a clock on the face we measure -_time_, so by the transit method, as Halley and Delisle respectively -suggested its use, we determine Venus’s position on the sun’s face, -by observing the difference of the time she takes in crossing, or the -difference of the time at which she begins to cross, or passes off, his -face. - -Besides the advantage of having a dial-face like the sun’s on which -thus to determine positions, the transit method deals with Venus when -at her nearest, or about 25 million miles from us, instead of the sun -at his greater distance of from 90½ to 93½ millions of miles. Yet we -do not get the entire advantage of this relative proximity of Venus. -For the dial-face—the sun, that is—changes its position too—in less -degree than Venus changes hers, but still so much as largely to reduce -her seeming displacement. The sun being further away as 92 to 25, is -less displaced as 25 to 92. Venus’s displacement is thus diminished by -25/92nds of its full amount, leaving only 67/92nds. Practically, then, -the advantage of observing Venus, so far as distance is concerned, is -the same as though, instead of being at a distance of only 25 million -miles, her distance were greater as 92 to 67, giving as her effective -distance when in transit some 34,300,000 miles. - -All the methods of observing Venus in transit are affected in _this_ -respect. Astronomers were not content during the recent transit to use -Halley’s and Delisle’s two time methods (which may be conveniently -called the duration method and the epoch method), but endeavoured to -determine the position of Venus on the sun’s face directly, both by -observation and by photography. The heliometer was the instrument -specially used for the former purpose; and as, in one of the new -methods to be presently described, this is the most effective of all -available instruments, a few words as to its construction will not be -out of place. - -The heliometer, then, is a telescope whose object-glass (that is, -the large glass at the end towards the object observed) is divided -into two halves along a diameter. When these two halves are exactly -together—that is, in the position they had before the glass was -divided—of course they show any object to which they may be directed -precisely as they would have done before the glass was cut. But if, -without separating the straight edges of the two semicircular glasses, -one be made to slide along the other, the images formed by the two -no longer coincide.[9] Thus, if we are looking at the sun we see -two overlapping discs, and by continuing to turn the screw or other -mechanism which carries our half-circular glass past the other, the -disc-images of the sun may be brought entirely clear of each other. -Then we have two suns in the same field of view, seemingly in contact, -or nearly so. Now, if we have some means of determining how far the -movable half-glass has been carried past the other to bring the two -discs into apparently exact contact, we have, in point of fact, a -measure of the sun’s apparent diameter. We can improve this estimate by -carrying back the movable glass till the images coincide again, then -further back till they separate the other way and finally are brought -into contact on that side. The entire range, from contact on one side -to contact on the other side, gives twice the entire angular span of -the sun’s diameter; and the half of this is more likely to be the true -measure of the diameter, than the range from coincident images to -contact either way, simply because instrumental errors are likely to be -more evenly distributed over the double motion than over the movement -on either side of the central position. The heliometer derived its -name—which signifies sun-measurer—from this particular application of -the instrument. - -It is easily seen how the heliometer was made available in determining -the position of Venus at any instant during transit. The observer -could note what displacement of the two half-glasses was necessary to -bring the black disc of Venus on one image of the sun to the edge of -the other image, first touching on the inside and then on the outside. -Then, reversing the motion, he could carry her disc to the opposite -edge of the other image of the sun, first touching on the inside and -then on the outside. Lord Lindsay’s private expedition—one of the -most munificent and also one of the most laborious contributions to -astronomy ever made—was the only English expedition which employed -the heliometer, none of our public observatories possessing such an -instrument, and official astronomers being unwilling to ask Government -to provide instruments so costly. The Germans, however, and the -Russians employed the heliometer very effectively. - -Next in order of proximity, for the employment of the direct surveying -method, is the planet Mars when he comes into opposition (or on the -same line as the earth and sun) in the order - - Sun____________________________Earth__________Mars, - -at a favourable part of his considerably eccentric orbit. His distance -then may be as small as 34½ millions of miles; and we have in his case -to make no reduction for the displacement of the background on which -his place is to be determined. That background is the star sphere, -his place being measured from that of stars near which his apparent -path on the heavens carries him; and the stars are so remote that -the displacement due to a distance of six or seven thousand miles -between two observers on the earth is to all intents and purposes -nothing. The entire span of the earth’s orbit round the sun, though -amounting to 184 millions of miles, is a mere point as seen from all -save ten or twelve stars; how utterly evanescent, then, the span of -the earth’s globe—less than the 23,000th part of her orbital range! -Thus the entire displacement of Mars due to the distance separating -the terrestrial observers comes into effect. So that, in comparing the -observation of Mars in a favourable opposition with that of Venus in -transit, we may fairly say that, so far as surveying considerations are -concerned, the two planets are equally well suited for the astronomer’s -purpose. Venus’s less distance of 25 millions of miles is effectively -increased to 34⅓ millions by the displacement of the solar background -on which we see her when in transit; while Mars’s distance of about -34½ millions of miles remains effectively the same when we measure his -displacement from neighbouring fixed stars. - -But in many respects Mars is superior to Venus for the purpose of -determining the sun’s distance. Venus can only be observed at her -nearest when in transit, and transit lasts but a few hours. Mars can -be observed night after night for a fortnight or so, during which his -distance still remains near enough to the least or opposition distance. -Again, Venus being observed on the sun, all the disturbing influences -due to the sun’s heat are at work in rendering the observation -difficult. The air between us and the sun at such a time is disturbed -by undulations due in no small degree to the sun’s action. It is true -that we have not, in the case of Mars, any means of substituting time -measures or time determinations for measures of position, as we have -in Venus’s case, both with Halley’s and Delisle’s methods. But to say -the truth, the advantage of substituting these time observations has -not proved so great as was expected. Venus’s unfortunate deformity of -figure when crossing the sun’s edge renders the determination of the -exact moments of her entry on the sun’s face and of her departure from -it by no means so trustworthy as astronomers could wish. On the whole, -Mars would probably have the advantage even without that point in his -favour which has now to be indicated. - -Two methods of observing Mars for determining the sun’s distance are -available, both of which, as they can be employed in applying one of -the new methods, may conveniently be described at this point. - -An observer far to the north of the earth’s equator sees Mars at -midnight, when the planet is in opposition, displaced somewhat to -the south of his true position—that is, of the position he would -have as supposed to be seen from the centre of the earth. On the -other hand, an observer far to the south of the equator sees Mars -displaced somewhat to the north of his true position. The difference -may be compared to different views of a distant steeple (projected, -let us suppose, against a much more remote hill), from the uppermost -and lowermost windows of a house corresponding to the northerly and -southerly stations on the earth, and from a window on the middle -story corresponding to a view of Mars from the earth’s centre. By -ascertaining the displacement of the two views of Mars obtained from -a station far to the north and another station far to the south, -the astronomer can infer the distance of the planet, and thence the -dimensions of the solar system. The displacement is determinable by -noticing Mars’s position with respect to stars which chance to be close -to him. For this purpose the heliometer is specially suitable, because, -having first a view of Mars and some companion stars as they actually -are placed, the observer can, by suitably displacing the movable -half-glass, bring the star into apparent contact with the planet, first -on one side of its disc, and then on the other side—the mean of the -two resulting measures giving, of course, the distance between the star -and the centre of the disc. - -This method requires that there shall be two observers, one at a -northern station, as Greenwich, or Paris, or Washington, the other at -a southern station, as Cape Town, Cordoba, or Melbourne. The base-line -is practically a north-and-south line; for though the two stations may -not lie in the same, or nearly the same, longitude, the displacement -determined is in reality that due to their difference of latitude only, -a correction being made for their difference of longitude. - -The other method depends, not on displacement of two observers north -and south, or difference of latitude, but on displacement east and -west. Moreover, it does not require that there shall be two observers -at stations far apart, but uses the observations made at one and the -same stations at different times. The earth, by turning on her axis, -carries the observer from the west to the east of an imaginary line -joining the earth’s centre and the centre of Mars. When on the west -of that line, or in the early evening, he sees Mars displaced towards -the east of the planet’s true position. After nine or ten hours the -observer is carried as far to the east of that line, and sees Mars -displaced towards the west of his true position. Of course Mars has -moved in the interval. He is, in fact, in the midst of his retrograde -career. But the astronomer knows perfectly well how to take that -motion into account. Thus, by observing the two displacements, or the -total displacement of Mars from east to west on account of the earth’s -rotation, one and the same observer can, in the course of a single -favourable night, determine the sun’s distance. And in passing, it may -be remarked that this is the only general method of which so much can -be said. By some of the others an astronomer can, indeed, estimate the -sun’s distance without leaving his observatory—at least, theoretically -he can do so. But many years of observation would be required before he -would have materials for achieving this result. On the other hand, one -good pair of observations of Mars, in the evening and in the morning, -from a station near the equator, would give a very fair measure of -the sun’s distance. The reason why the station should be near the -equator will be manifest, if we consider that at the poles there -would be no displacement due to rotation; at the equator the observer -would be carried round a circle some twenty-five thousand miles in -circumference; and the nearer his place to the equator the larger -the circle in which he would be carried, and (_cæteris paribus_) the -greater the evening and morning displacement of the planet. - -Both these methods have been successfully applied to the problem of -determining the sun’s distance, and both have recently been applied -afresh under circumstances affording exceptionally good prospects of -success, though as yet the results are not known. - -It is, however, when we leave the direct surveying method to which -both the observations of Venus in transit and Mars in opposition -belong (in all their varieties), that the most remarkable, and, one -may say, unexpected methods of determining the sun’s distance present -themselves. Were not my subject a wide one, I would willingly descant -at length on the marvellous ingenuity with which astronomers have -availed themselves of every point of vantage whence they might measure -the solar system. But, as matters actually stand, I must be content -to sketch these other methods very roughly, only indicating their -characteristic features. - -One of them is in some sense related to the method by actual survey, -only it takes advantage, not of the earth’s dimensions, but of the -dimensions of her orbit round the common centre of gravity of herself -and the moon. This orbit has a diameter of about six thousand miles; -and as the earth travels round it, speeding swiftly onwards all the -time in her path round the sun, the effect is the same as though the -sun, in his apparent circuit round the earth, were constantly circling -once in a lunar month around a small subordinate orbit of precisely the -same size and shape as that small orbit in which the earth circuits -round the moon’s centre of gravity. He appears then sometimes displaced -about 3000 miles on one side, sometimes about 3000 miles on the other -side of the place which he would have if our earth were not thus -perturbed by the moon. But astronomers can note each day where he is, -and thus learn by how much he seems displaced from his mean position. -Knowing that his greatest displacement corresponds to so many miles -exactly, and noting what it seems to be, they learn, in fact, how large -a span of so many miles (about 3000) looks at the sun’s distance. -Thus they learn the sun’s distance precisely as a rifleman learns the -distance of a line of soldiers when he has ascertained their apparent -size—for only at a certain distance can an object of known size have a -certain apparent size. - -The moon comes in, in another way, to determine the sun’s distance -for us. We know how far away she is from the earth, and how much, -therefore, she approaches the sun when new, and recedes from him when -full. Calling this distance, roughly, a 390th part of the sun’s, her -distance from him when new, her mean distance, and her distance from -him when full, are as the numbers 389, 390, 391. Now, these numbers -do not quite form a continued proportion, though they do so very -nearly (for 389 is to 390 as 390 to 391-1/400). If they were in exact -proportion, the sun’s disturbing influence on the moon when she is at -her nearest would be exactly equal to his disturbing influence on the -moon when at her furthest from him—or generally, the moon would be -exactly as much disturbed (on the average) in that half of her path -which lies nearer to the sun as in that half which lies further from -him. As matters are, there is a slight difference. Astronomers can -measure this difference; and measuring it, they can ascertain what the -actual numbers are for which I have roughly given the numbers 389, 390, -and 391; in other words, they can ascertain in what degree the sun’s -distance exceeds the moon’s. This is equivalent to determining the -sun’s distance, since the moon’s is already known. - -Another way of measuring the sun’s distance has been “favoured” -by Jupiter and his family of satellites. Few would have thought, -when Römer first explained the delay which occurs in the eclipse of -these moons while Jupiter is further from us than his mean distance, -that that explanation would lead up to a determination of the sun’s -distance. But so it happened. Römer showed that the delay is not in the -recurrence of the eclipses, but in the arrival of the news of these -events. From the observed time required by light to traverse the extra -distance when Jupiter is nearly at his furthest from us, the time in -which light crosses the distance separating us from the sun is deduced; -whence, if that distance has been rightly determined, the velocity of -light can be inferred. If this velocity is directly measured in any -way, and found not to be what had been deduced from the adopted measure -of the sun’s distance, the inference is that the sun’s distance has -been incorrectly determined. Or, to put the matter in another way, we -know exactly how many minutes and seconds light takes in travelling to -us from the sun; if, therefore, we can find out how fast light travels -we know how far away the sun is. - -But who could hope to measure a velocity approaching 200,000 miles in a -second? At a first view the task seems hopeless. Wheatstone, however, -showed how it might be accomplished, measuring by his method the yet -greater velocity of freely conducted electricity. Foucault and Fizeau -measured the velocity of light; and recently Cornu has made more exact -measurements. Knowing, then, how many miles light travels in a second, -and in how many seconds it comes to us from the sun, we know the sun’s -distance. - -The first of the methods which I here describe as new methods must next -be considered. It is one which Leverrier regards as the method of the -future. In fact, so highly does he esteem it, that, on its account, he -may almost be said to have refused to sanction in any way the French -expeditions for observing the transit of Venus in 1874. - -The members of the sun’s family perturb each other’s motions in a -degree corresponding with their relative mass, compared with each -other and with the sun. Now, it can be shown (the proof would be -unsuitable to these pages,[10] but I have given it in my treatise -on “The Sun”) that no change in our estimate of the sun’s distance -affects our estimate of his mean density as compared with the earth’s. -His substance has a mean density equal to one-fourth of the earth’s, -whether he be 90 millions or 95 millions of miles from us, or indeed -whether he were ten millions or a million million miles from us -(supposing for a moment our measures did not indicate his real distance -more closely). We should still deduce from calculation the same -unvarying estimate of his mean density. It follows that the nearer -any estimate of his distance places him, and therefore the smaller it -makes his estimated volume, the smaller also it makes his estimated -mass, and in precisely the same degree. The same is true of the planets -also. We determine Jupiter’s mass, for example (at least, this is the -simplest way), by noting how he swerves his moons at their respective -(estimated) distances. If we diminish our estimate of their distances, -we diminish at the same time our estimate of Jupiter’s attractive -power, and in such degree, it may be shown (see note), as precisely to -correspond with our changed estimate of his size, leaving our estimate -of his mean density unaltered. And the same is true for all methods of -determining Jupiter’s mass. Suppose, then, that, adopting a certain -estimate of the scale of the solar system, we find that the resulting -estimate of the masses of the planets and of the sun, _as compared with -the earth’s mass_, from their observed attractive influences on bodies -circling around them or passing near them, accords with their estimated -perturbing action as compared with the earth’s,—then we should infer -that our estimate of the sun’s distance or of the scale of the solar -system was correct. But suppose it appeared, on the contrary, that -the earth took a larger or a smaller part in perturbing the planetary -system than, according to our estimate of her relative mass, she -should do,—then we should infer that the masses of the other members -of the system had been overrated or underrated; or, in other words, -that the scale of the solar system had been overrated or underrated -respectively. Thus we should be able to introduce a correction into our -estimate of the sun’s distance. - -Such is the principle of the method by which Leverrier showed that in -the astronomy of the future the scale of the solar system may be very -exactly determined. Of course, the problem is a most delicate one. The -earth plays, in truth, but a small part in perturbing the planetary -system, and her influence can only be distinguished satisfactorily -(at present, at any rate) in the case of the nearer members of the -solar family. Yet the method is one which, unlike others, will have -an accumulative accuracy, the discrepancies which are to test the -result growing larger as time proceeds. The method has already been -to some extent successful. It was, in fact, by observing that the -motions of Mercury are not such as can be satisfactorily explained by -the perturbations of the earth and Venus according to the estimate of -relative masses deducible from the lately discarded value of the sun’s -distance, that Leverrier first set astronomers on the track of the -error affecting that value. He was certainly justified in entertaining -a strong hope that hereafter this method will be exceedingly effective. - -We come next to a method which promises to be more quickly if not more -effectively available. - -Venus and Mars approach the orbit of our earth more closely than any -other planets, Venus being our nearest neighbour on the one side, and -Mars on the other. Looking beyond Venus, we find only Mercury (and the -mythical Vulcan), and Mercury can give no useful information respecting -the sun’s distance. He could scarcely do so even if we could measure -his position among the stars when he is at his nearest, as we can -that of Mars; but as he can only then be fairly seen when he transits -the sun’s face, and as the sun is nearly as much displaced as Mercury -by change in the observer’s station, the difference between the two -displacements is utterly insufficient for accurate measurement. But, -when we look beyond the orbit of Mars, we find certain bodies which are -well worth considering in connection with the problem of determining -the sun’s distance. I refer to the asteroids, the ring of small planets -travelling between the paths of Mars and Jupiter, but nearer (on the -whole[11]) to the path of Mars than to that of Jupiter. - -The asteroids present several important advantages over even Mars and -Venus. - -Of course, none of the asteroids approach so near to the earth as Mars -at his nearest. His least distance from the sun being about 127 million -miles, and the earth’s mean distance about 92 millions, with a range of -about a million and a half on either side, owing to the eccentricity of -her orbit, it follows that he _may_ be as near as some 35 million miles -(rather less in reality) from the earth when the sun, earth, and Mars -are nearly in a straight line and in that order. The least distance of -any asteroid from the sun amounts to about 167 million miles, so that -their least distance from the earth cannot at any time be less than -about 73,500,000 miles, even if the earth’s greatest distance from -the sun corresponded with the least distance of one of these closely -approaching asteroids. This, by the way, is not very far from being the -case with the asteroid Ariadne, which comes within about 169 million -miles of the sun at her nearest, her place of nearest approach being -almost exactly in the same direction from the sun as the earth’s place -of greatest recession, reached about the end of June. So that, whenever -it so chances that Ariadne comes into opposition in June, or that the -sun, earth, and Ariadne are thus placed— - - Sun________Earth________Ariadne, - -Ariadne will be but about 75,500,000 miles from the earth. Probably no -asteroid will ever be discovered which approaches the earth much more -nearly than this; and this approach, be it noticed, is not one which -can occur in the case of Ariadne except at very long intervals. - -But though we may consider 80 millions of miles as a fair average -distance at which a few of the most closely approaching asteroids may -be observed, and though this distance seems very great by comparison -with Mars’s occasional opposition distance of 35 million miles, yet -there are two points in which asteroids have the advantage over Mars. -First, they are many, and several among them can be observed under -favourable circumstances; and in the multitude of observations there -is safety. In the second place, which is the great and characteristic -good quality of this method of determining the sun’s distance, they do -not present a disc, like the planet Mars, but a small star-like point. -When we consider the qualities of the heliometric method of measuring -the apparent distance between celestial objects, the advantage of -points of light over discs will be obvious. If we are measuring the -apparent distance between Mars and a star, we must, by shifting the -movable object-glass, bring the star’s image into apparent contact -with the disc-image of Mars, first on one side and then on the other, -taking the mean for the distance between the centres. Whereas, when we -determine the distance between a star and an asteroid, we have to bring -two star-like points (one a star, the other the asteroid) into apparent -coincidence. We can do this in two ways, making the result so much the -more accurate. For consider what we have in the field of view when the -two halves of the object-glass coincide. There is the asteroid and -close by there is the star whose distance we seek to determine in order -to ascertain the position of the asteroid on the celestial sphere. -When the movable half is shifted, the two images of star and asteroid -separate; and by an adjustment they can be made to separate along the -line connecting them. Suppose, then, we first make the movable image -of the asteroid travel away from the fixed image (meaning by movable -and fixed images, respectively, those given by the movable and fixed -halves of the object-glass), towards the fixed image of the star—the -two points, like images, being brought into coincidence, we have the -measure of the distance between star and asteroid. Now reverse the -movement, carrying back the movable images of the asteroid and star -till they coincide again with their fixed images. This movement gives -us a second measure of the distance, which, however, may be regarded as -only a reversed repetition of the preceding. But now, carrying on the -reverse motion, the moving images of star and asteroid separate from -their respective fixed images, the moving image of the star drawing -near to the fixed image of the asteroid and eventually coinciding with -it. Here we have a third measure of the distance, which is independent -of the two former. Reversing the motion, and carrying the moving -images to coincidence with the fixed images, we have a fourth measure, -which is simply the third reversed. These four measures will give a -far more satisfactory determination of the true apparent distance -between the star and the asteroid than can, under any circumstances, -be obtained in the case of Mars and a star. Of course, a much more -exact determination is required to give satisfactory measures of the -asteroid’s real distance from the earth in miles, for a much smaller -error would vitiate the estimate of the asteroid’s distance than would -vitiate to the same degree the estimate of Mars’s distance: for the -apparent displacements of the asteroid as seen either from Northern and -Southern stations, or from stations east and west of the meridian, are -very much less than in the case of Mars, owing to his great proximity. -But, on the whole, there are reasons for believing that the advantage -derived from the nearness of Mars is almost entirely counterbalanced -by the advantage derived from the neatness of the asteroid’s image. -And the number of asteroids, with the consequent power of repeating -such measurements many times for each occasion on which Mars has been -thus observed, seem to make the asteroids—so long regarded as very -unimportant members of the solar system—the bodies from which, after -all, we shall gain our best estimate of the sun’s distance; that is, of -the scale of the solar system. - - * * * * * - -Since the above pages were written, the results deduced from the -observations made by the British expeditions for observing the transit -of December 9, 1874, have been announced by the Astronomer Royal. -It should be premised that they are not the results deducible from -the entire series of British observations, for many of them can only -be used effectively in combination with observations made by other -nations. For instance, the British observations of the duration of the -transit as seen from Southern stations are only useful when compared -with observations of the duration of the transit as seen from Northern -stations, and no British observations of this kind were taken at -Northern stations, or could be taken at any of the British Northern -stations except one, where chief reliance was placed on photographic -methods. The only British results as yet “worked up” are those which -are of themselves sufficient, theoretically, to indicate the sun’s -distance, viz., those which indicated the epochs of the commencement of -transit as seen from Northern and Southern stations, and those which -indicated the epochs of the end of transit as seen from such stations. -The Northern and Southern epochs of commencement compared together -suffice _of themselves_ to indicate the sun’s distance; so also do the -epochs of the end of transit suffice _of themselves_ for that purpose. -Such observations belong to the Delislean method, which was the subject -of so much controversy for two or three years before the transit took -place. Originally it had been supposed that only observations by that -method were available, and the British plans were formed upon that -assumption. When it was shown that this assumption was altogether -erroneous, there was scarcely time to modify the British plans so that -of themselves they might provide for the other or Halleyan method. -But the Southern stations which were suitable for that method were -strengthened; and as other nations, especially America and Russia, -occupied large numbers of Northern stations, the Halleyan method was, -in point of fact, effectually provided for—a fortunate circumstance, -as will presently be seen. - -The British operations, then, thus far dealt with, were based on -Delisle’s method; and as they were carried out with great zeal and -completeness, we may consider that the result affords an excellent -test of the qualities of this method, and may supply a satisfactory -answer to the questions which were under discussion in 1872–74. Sir -George Airy, indeed, considers that the zeal and completeness with -which the British operations were carried out suffice to set the -result obtained from them above all others. But this opinion is based -rather on personal than on strictly scientific grounds. It appears to -me that the questions to be primarily decided are whether the results -are in satisfactory agreement (i) _inter se_ and (ii) with the general -tenor of former researches. In other words, while the Astronomer Royal -considers that the method and the manner of its application must -be considered so satisfactory that the results are to be accepted -unquestionably, it appears to me that the results must be carefully -questioned (as it were) to see whether the method, and the observations -by it, are satisfactory. In the first place, the result obtained -from Northern and Southern observations of the commencement ought to -agree closely with the result obtained from Northern and Southern -observations of the end of transit. Unfortunately, they differ rather -widely. The sun’s distance by the former observations comes out about -one million miles greater than the distance determined by the latter -observations. - -This should be decisive, one would suppose. But it is not all. -The mean of the entire series of observations by Delisle’s method -comes out nearly one million miles greater than the mean deduced by -Professor Newcomb from many entire series of observations by six -different methods, all of which may fairly be regarded as equal in -value to Delisle’s, while three are regarded by most astronomers as -unquestionably superior to it. Newcomb considers the probable limits of -error in his evaluation from so many combined series of observations -to be about 100,000 miles. Sir G. Airy will allow no wider limits of -error for the result of the one series his observers have obtained than -200,000 miles. Thus the greatest value admitted by Newcomb falls short -of the least value admitted by Sir G. Airy, by nearly 700,000 miles. - -The obvious significance of this result should be, one would suppose, -that Delisle’s method is not quite so effective as Sir G. Airy -supposed; and the wide discordance between the several results, of -which the result thus deduced is the mean, should prove this, one -would imagine, beyond all possibility of question. The Astronomer -Royal thinks differently, however. In his opinion, the wide difference -between his result and the mean of all the most valued results by other -astronomers, indicates the superiority of Delisle’s method, not its -inadequacy to the purpose for which it has been employed. - -Time will shortly decide which of these views is correct; but, for my -own part, I do not hesitate to express my own conviction that the sun’s -distance lies very near the limits indicated by Newcomb, and therefore -is several hundred thousand miles less than the minimum distance -allowed by the recently announced results. - - - - -DRIFTING LIGHT-WAVES. - - -The method of measuring the motion of very swiftly travelling bodies -by noting changes in the light-waves which reach us from them—one -of the most remarkable methods of observation ever yet devised by -man—has recently been placed upon its trial, so to speak; with results -exceedingly satisfactory to the students of science who had accepted -the facts established by it. The method will not be unfamiliar to many -of my readers. The principle involved was first noted by M. Doppler, -but not in a form which promised any useful results. The method -actually applied appears to have occurred simultaneously to several -persons, as well theorists as observers. Thus Secchi claimed in March, -1868, to have applied it though unsuccessfully; Huggins in April, 1868, -described his successful use of the method. I myself, wholly unaware -that either of these observers was endeavouring to measure celestial -motions by its means, described the method, in words which I shall -presently quote, in the number of _Fraser’s Magazine_ for January, -1868, two months before the earliest enunciation of its nature by the -physicists just named. - -It will be well briefly to describe the principle of this interesting -method, before considering the attack to which it has been recently -subjected, and its triumphant acquittal from defects charged against -it. This brief description will not only be useful to those readers who -chance not to be acquainted with the method, but may serve to remove -objections which suggest themselves, I notice, to many who have had -the principle of the method imperfectly explained to them. - -Light travels from every self-luminous body in waves which sweep -through the ether of space at the rate of 185,000 miles per second. -The whole of that region of space over which astronomers have extended -their survey, and doubtless a region many millions of millions of times -more extended, may be compared to a wave-tossed sea, only that instead -of a wave-tossed surface, there is wave-tossed space. At every point, -through every point, along every line, athwart every line, myriads of -light-waves are at all times rushing with the inconceivable velocity -just mentioned. - -It is from such waves that we have learned all we know about the -universe outside our own earth. They bring to our shores news from -other worlds, though the news is not always easy to decipher. - -Now, seeing that we are thus immersed in an ocean, athwart which -infinite series of waves are continually rushing, and moreover that -we ourselves, and every one of the bodies whence the waves proceed -either directly or after reflection, are travelling with enormous -velocity through this ocean, the idea naturally presents itself that we -may learn something about these motions (as well as about the bodies -themselves whence they proceed), by studying the aspect of the waves -which flow in upon us in all directions. - -Suppose a strong swimmer who knew that, were he at rest, a certain -series of waves would cross him at a particular rate—ten, for -instance, in a minute—were to notice that when he was swimming -directly facing them, eleven passed him in a minute: he would be able -at once to compare his rate of swimming with the rate of the waves’ -motion. He would know that while ten waves had passed him on account -of the waves’ motion, he had by his own motion caused yet another wave -to pass him, or in other words, had traversed the distance from one -wave-crest to the next Thus he would know that his rate was one-tenth -that of the waves. Similarly if, travelling the same way as the waves, -he found that only nine passed him in a minute, instead of ten. - -Again, it is not difficult to see that if an observer were at rest, -and a body in the water, which by certain motions produced waves, -were approaching or receding from the observer, the waves would come -in faster in the former case, slower in the latter, than if the body -were at rest. Suppose, for instance, that some machinery at the bows -of a ship raised waves which, if the ship were at rest, would travel -along at the rate of ten a minute past the observer’s station. Then -clearly, if the ship approached him, each successive wave would have -a shorter distance to travel, and so would reach him sooner than it -otherwise would have done. Suppose, for instance, the ship travelled -one-tenth as fast as the waves, and consider ten waves proceeding from -her bows—the first would have to travel a certain distance before -reaching the observer; the tenth, starting a minute later, instead of -having to travel the same distance, would have to travel this distance -diminished by the space over which the ship had passed in one minute -(which the wave itself passes over in the tenth of a minute); instead, -then, of reaching the observer one minute after the other, it would -reach him nine-tenths of a minute after the first. Thus it would seem -to him as though the waves were coming in faster than when the ship was -at rest, in the proportion of ten to nine, though in reality they would -be travelling at the same rate as before, only arriving in quicker -succession, because of the continual shortening of the distance they -had to travel, on account of the ship’s approach. If he knew precisely -how fast they _would_ arrive if the ship were at rest, and determined -precisely how fast they _did_ arrive, he would be able to determine at -once the rate of the ship’s approach, at least the proportion between -her rate and the rate of the waves’ motion. Similarly if, owing to the -ship’s recession, the apparent rate of the waves’ motion were reduced, -it is obvious that the actual change in the wave motion would not be -a difference of rate; but, in the case of the approaching ship, the -breadth from crest to crest would be reduced, while in the case of a -receding ship the distance from crest to crest would be increased. - -If the above explanation should still seem to require closer attention -than the general reader may be disposed to give, the following, -suggested by a friend of mine—a very skilful mathematician—will be -found still simpler: Suppose a stream to flow quite uniformly, and that -at one place on its banks an observer is stationed, while at another -higher up a person throws corks into the water at regular intervals, -say ten corks per minute; then these will float down and pass the other -observer, wherever he may be, at the rate of ten per minute, _if_ -the cork-thrower is at rest. But if he saunters either up-stream or -down-stream, the corks will no longer float past the other at the exact -rate of ten per minute. If the thrower is sauntering down-stream, then, -between throwing any cork and the next, he has walked a certain way -down, and the tenth cork, instead of having to travel the same distance -as the first before reaching the observer, has a shorter distance to -travel, and so reaches that observer sooner. Or in fact, which some may -find easier to see, this cork will be nearer to the first cork than it -would have been if the thrower had remained still. The corks will lie -at equal distances from each other, but these equal distances will be -less than they would have been if the observer had been at rest. If, on -the contrary, the cork-thrower saunters up-stream, the corks will be -somewhat further apart than if he had remained at rest. And supposing -the observer to know beforehand that the corks would be thrown in -at the rate of ten a minute, he would know, if they passed him at a -greater rate than ten a minute (or, in other words, at a less distance -from each other than the stream traversed in the tenth of a minute), -that the cork-thrower was travelling down-stream or approaching him; -whereas, if fewer than ten a minute passed him, he would know that the -cork-thrower was travelling away from him, or up-stream. But also, if -the cork-thrower were at rest, and the observer moved up-stream—that -is, towards him—the corks would pass him at a greater rate than ten a -minute; whereas, if the observer were travelling down-stream, or from -the thrower, they would pass him at a slower rate. If both were moving, -it is easily seen that if their movement brought them nearer together, -the number of corks passing the observer per minute would be increased, -whereas if their movements set them further apart, the number passing -him per minute would be diminished. - -These illustrations, derived from the motions of water, suffice in -reality for our purpose. The waves which are emitted by luminous -bodies in space travel onwards like the water-waves or the corks of -the preceding illustrations. If the body which emits them is rapidly -approaching us, the waves are set closer together or narrowed; whereas, -if the body is receding, they are thrown further apart or broadened. -And if we can in any way recognize such narrowing or broadening of the -light-waves, we know just as certainly that the source of light is -approaching us or receding from us (as the case may be) as our observer -in the second illustration would know from the distance between the -corks whether his friend, the cork-thrower, was drawing near to him or -travelling away from him. - -But it may be convenient to give another illustration, drawn from -waves, which, like those of light, are not themselves discernible -by our senses—I refer to those aerial waves of compression and -rarefaction which produce what we call sound. These waves are not -only in this respect better suited than water-waves to illustrate -our subject, but also because they travel in all directions through -aerial space, not merely along a surface. The waves which produce -a certain note, that is, which excite in our minds, through the -auditory nerve, the impression corresponding to a certain tone, have -a definite length. So long as the observer, and a source of sound -vibrating in one particular period, remain both in the same place, -the note is unchanged in tone, though it may grow louder or fainter -according as the vibrations increase or diminish in amplitude. But if -the source of sound is approaching the hearer, the waves are thrown -closer together and the sound is rendered more acute (the longer waves -giving the deeper sound); and, on the other hand, if the source of -sound is receding from the hearer, the waves are thrown further apart -and the sound is rendered graver. The _rationale_ of these changes is -precisely the same as that of the changes described in the preceding -illustrations. It might, perhaps, appear that in so saying we were -dismissing the illustration from sound, at least as an independent -one, because we are explaining the illustration by preceding -illustrations. But in reality, while there is absolutely nothing -new to be said respecting the increase and diminution of distances -(as between the waves and corks of the preceding illustration), -the illustration from sound has the immense advantage of admitting -readily of experimental tests. It is necessary only that the rate of -approach or recession should bear an appreciable proportion to the -rate at which sound travels. For waves are shortened or lengthened by -approach or recession by an amount which bears to the entire length of -the wave the same proportion which the rate of approach or recession -bears to the rate of the wave’s advance. Now it is not very difficult -to obtain rates of approach or recession fairly comparable with the -velocity of sound—about 364 yards per second. An express train at -full speed travels, let us say, about 1800 yards per minute, or 30 -yards per second. Such a velocity would suffice to reduce all the -sound-waves proceeding from a bell or whistle upon the engine, by -about one-twelfth part, for an observer at rest on a station platform -approached by the engine. On the contrary, after the engine had passed -him, the sound-waves proceeding from the same bell or whistle would be -lengthened by one-twelfth. The difference between the two tones would -be almost exactly three semitones. If the hearer, instead of being on -a platform, were in a train carried past the other at the same rate, -the difference between the tone of the bell in approaching and its -tone in receding would be about three tones. It would not be at all -difficult so to arrange matters, that while two bells were sounding the -same note—_Mi_, let us say—one bell on one engine the other on the -other, a traveller by one should hear his own engine’s bell, the bell -of the approaching engine, and the bell of the same engine receding, -as the three notes—_Do_—_Mi_—_Sol_, whose wave-lengths are as the -numbers 15, 12, and 10. We have here differences very easily to be -recognized even by those who are not musicians. Every one who travels -much by train must have noticed how the tone of a whistle changes as -the engine sounding it travels past. The change is not quite sharp, -but very rapid, because the other engine does not approach with a -certain velocity up to a definite moment and then recede with the same -velocity. It could only do this by rushing through the hearer, which -would render the experiment theoretically more exact but practically -unsatisfactory. As it rushes past instead of through him, there is a -brief time during which the rate of approach is rapidly being reduced -to nothing, followed by a similarly brief time during which the rate of -recession gradually increases from nothing up to the actual rate of the -engines’ velocities added together.[12] The change of tone may be thus -illustrated:— - -[Illustration] - -A B representing the sound of the approaching whistle, B C representing -the rapid degradation of sound as the engine rushes close past the -hearer, and C D representing the sound of the receding whistle. When -a bell is sounded on the engine, as in America, the effect is better -recognized, as I had repeated occasion to notice during my travels in -that country. Probably this is because the tone of a bell is in any -case much more clearly recognized than the tone of a railway whistle. -The change of tone as a clanging bell is carried swiftly past (by the -combined motions of both trains) is not at all of such a nature as to -require close attention for its detection. - -However, the apparent variation of sound produced by rapid approach or -recession has been tested by exact experiments. On a railway uniting -Utrecht and Maarsen “were placed,” the late Professor Nichol wrote, -“at intervals of something upwards of a thousand yards, three groups -of musicians, who remained motionless during the requisite period. -Another musician on the railway sounded at intervals one uniform note; -and its effects on the ears of the stationary musicians have been -fully published. From these, certainly—from the recorded changes -between grave and the more acute, and _vice versâ_,—confirming, even -_numerically_, what the relative velocities might have enabled one to -predict, it appears justifiable to conclude that the general theory is -correct; and that the note of any sound may be greatly modified, if -not wholly changed, by the velocity of the individual hearing it,” or, -he should have added, by the velocity of the source of sound: perhaps -more correct than either, is the statement that the note may be altered -by the approach or recession of the source of sound, whether that be -caused by the motion of the sounding body, or of the hearer himself, or -of both. - -It is difficult, indeed, to understand how doubt can exist in the -mind of any one competent to form an opinion on the matter, though, -as we shall presently see, some students of science and one or two -mathematicians have raised doubts as to the validity of the reasoning -by which it is shown that a change should occur. That the reasoning is -sound cannot, in reality, be questioned, and after careful examination -of the arguments urged against it by one or two mathematicians, I -can form no other opinion than that these arguments amount really -but to an expression of inability to understand the matter. This -may seem astonishing, but is explained when we remember that some -mathematicians, by devoting their attention too particularly to special -departments, lose, to a surprising degree, the power of dealing with -subjects (even mathematical ones) outside their department. Apart -from the soundness of the reasoning, the facts are unmistakably in -accordance with the conclusion to which the reasoning points. Yet some -few still entertain doubts, a circumstance which may prove a source of -consolation to any who find themselves unable to follow the reasoning -on which the effects of approach and recession on wave-lengths depend. -Let such remember, however, that experiment in the case of the aerial -waves producing sound, accords perfectly with theory, and that the -waves which produce light are perfectly analogous (so far as this -particular point is concerned) with the waves producing sound. - -Ordinary white light, and many kinds of coloured light, may be compared -with _noise_—that is, with a multitude of intermixed sounds. But light -of one pure colour may be compared to sound of one determinate note. -As the aerial waves producing the effect of one definite tone are all -of one length, so the ethereal waves producing light of one definite -colour are all of one length. Therefore if we approach or recede from a -source of light emitting such waves, effects will result corresponding -with what has been described above for the case of water-waves and -sound-waves. If we approach the source of light, or if it approaches -us, the waves will be shortened; if we recede from it, or if it -recedes from us, the waves will be lengthened. But the colour of light -depends on its wave-length, precisely as the tone of sound depends on -its wave-length. The waves producing red light are longer than those -producing orange light, these are longer than the waves producing -yellow light; and so the wave-lengths shorten down from yellow to -green, thence to blue, to indigo, and finally to violet. Thus if a body -shining in reality with a pure green colour, approached the observer -with a velocity comparable with that of light, it would seem blue, -indigo, or violet, according to the rate of approach; whereas if it -rapidly receded, it would seem yellow, orange, or red, according to the -rate of recession. - -Unfortunately in one sense, though very fortunately in many much more -important respects, the rates of motion among the celestial bodies are -_not_ comparable with the velocity of light, but are always so much -less as to be almost rest by comparison. The velocity of light is about -187,000 miles per second, or, according to the measures of the solar -system at present in vogue (which will shortly have to give place to -somewhat larger measures, the result of observations made upon the -recent transit of Venus), about 185,000 miles per second. The swiftest -celestial motion of which we have ever had direct evidence was that of -the comet of the year 1843, which, at the time of its nearest approach -to the sun, was travelling at the rate of about 350 miles per second. -This, compared with the velocity of light, is as the motion of a person -taking six steps a minute, each less than half a yard long, to the -rush of the swiftest express train. No body within our solar system -can travel faster than this, the motion of a body falling upon the sun -from an infinite distance being only about 370 miles per second when it -reaches his surface. And though swifter motions probably exist among -the bodies travelling around more massive suns than ours, yet of such -motions we can never become cognizant. All the motions taking place -among the stars themselves would appear to be very much less in amount. -The most swiftly moving sun seems to travel but at the rate of about 50 -or 60 miles per second. - -Now let us consider how far a motion of 100 miles per second might be -expected to modify the colour of pure green light—selecting green as -the middle colour of the spectrum. The waves producing green light -are of such a length, that 47,000 of them scarcely equal in length a -single inch. Draw on paper an inch and divide it carefully into ten -equal parts, or take such parts from a well-divided rule; divide one -of these tenths into ten equal parts, as nearly as the eye will permit -you to judge; then one of these parts, or about half the thickness of -an average pin, would contain 475 of the waves of pure green light. -The same length would equal the length of 440 waves of pure yellow -light, and of 511 waves of pure blue light. (The green, yellow, and -blue, here spoken of, are understood to be of the precise colour of -the middle of the green, yellow, and blue parts of the spectrum.) Thus -the green waves must be increased in the proportion of 475 to 440 to -give yellow light, or reduced in the proportion of 511 to 475 to give -blue light. For the first purpose, the velocity of recession must bear -to the velocity of light the proportion which 30 bears to 475, or -must be equal to rather more than one-sixteenth part of the velocity -of light—say 11,600 miles per second. For the second purpose, the -velocity of approach must bear to the velocity of light the proportion -which 36 bears to 475, or must be nearly equal to one-thirteenth part -of the velocity of light—say 14,300 miles per second. But the motions -of the stars and other celestial bodies, and also the motions of matter -in the sun, and so forth, are very much less than these. Except in the -case of one or two comets (and always dismissing from consideration -the amazing apparent velocities with which comets’ tails _seem_ to -be formed), we may take 100 miles per second as the extreme limit of -velocity with which we have to deal, in considering the application -of our theory to the motions of recession and approach of celestial -bodies. Thus in the case of recession the greatest possible change -of colour in pure green light would be equivalent to the difference -between the medium green of the spectrum, and the colour 1-116th part -of the way from medium green to medium yellow; and in the case of -approach, the change would correspond to the difference between the -medium green and the colour 1-143rd part of the way from medium green -to medium blue. Let any one look at a spectrum of fair length, or even -at a correctly tinted painting of the solar spectrum, and note how -utterly unrecognizable to ordinary vision is the difference of tint for -even the twentieth part of the distance between medium green and medium -yellow on one side or medium blue on the other, and he will recognize -how utterly hopeless it would be to attempt to appreciate the change -of colour due to the approach or recession of a luminous body shining -with pure green light and moving at the tremendous rate of 100 miles -per second. It would be hopeless, even though we had the medium green -colour and the changed colour, either towards yellow or towards blue, -placed side by side for comparison—how much more when the changed -colour would have to be compared with the observer’s recollection of -the medium colour, as seen on some other occasion! - -But this is the least important of the difficulties affecting the -application of this method by noting change of colour, as Doppler -originally proposed. Another difficulty, which seems somehow to have -wholly escaped Doppler’s attention, renders the colour test altogether -unavailable. We do not get _pure_ light from any of the celestial -bodies except certain gaseous clouds or nebulæ. From every sun we get, -as from our own sun, all the colours of the rainbow. There may be an -excess of some colours and a deficiency of others in any star, so as -to give the star a tint, or even a very decided colour. But even a -blood-red star, or a deep-blue or violet star, does not shine with -pure light, for the spectroscope shows that the star has other colours -than those producing the prevailing tint, and it is only the great -_excess_ of red rays (all kinds of red, too) or of blue rays (of all -kinds), and so on, which makes the star appear red, or blue, and so on, -to the eye. By far the greater number of stars or suns show all the -colours of the rainbow nearly equally distributed, as in the case of -our own sun. Now imagine for a moment a white sun, which had been at -rest, to begin suddenly to approach us so rapidly (travelling more than -10,000 miles per second) that the red rays became orange, the orange -became yellow, the yellow green, the green blue, the blue indigo, the -indigo violet, while the violet waves became too short to affect the -sense of sight. Then, _if that were all_, that sun, being deprived of -the red part of its light, would shine with a slightly bluish tinge, -owing to the relative superabundance of rays from the violet end of -the spectrum. We should be able to recognize such a change, yet not -nearly so distinctly as if that sun had been shining with a pure green -light, and suddenly beginning to approach us at the enormous rate just -mentioned, changed in colour to full blue. _Though_, if that sun were -all the time approaching us at the enormous rate imagined, we should be -quite unable to tell whether its slightly bluish tinge were due to such -motion of approach or to some inherent blueness in the light emitted by -the star. Similarly, if a white sun suddenly began to recede so rapidly -that its violet rays were turned to indigo, the indigo to blue, and -so on, the orange rays turning to red, and the red rays disappearing -altogether, then, _if that were all_, its light would become slightly -reddish, owing to the relative superabundance of light from the red -end of the spectrum; and we might distinguish the change, yet not so -readily as if a sun shining with pure green light began to recede at -the same enormous rate, and so shone with pure yellow light. _Though_, -if that sun were all the time receding at that enormous rate, we should -be quite unable to tell whether its slightly reddish hue were due to -such motion of recession or to some inherent redness in its own lustre. -_But in neither case would that be all._ In the former, the red rays -would indeed become orange; but the rays beyond the red, which produce -no effect upon vision, would be converted into red rays, and fill up -the part of the spectrum deserted by the rays originally red. In the -latter, the violet rays would indeed become indigo; but the rays beyond -the violet, ordinarily producing no visible effect, would be converted -into violet rays, and fill up the part of the spectrum deserted by the -rays originally violet. Thus, despite the enormous velocity of approach -in one case and of recession in the other, there would be no change -whatever in the colour of the sun in either case. All the colours of -the rainbow would still be present in the sun’s light, and it would -therefore still be a white sun. - -Doppler’s method would thus fail utterly, even though the stars were -travelling hither and thither with motions a hundred times greater than -the greatest known stellar motions. - -This objection to Doppler’s theory, as originally proposed, was -considered by me in an article on “Coloured Suns” in _Fraser’s -Magazine_ for January, 1868. His theory, indeed, was originally -promulgated not as affording a means of measuring stellar motions, but -as a way of accounting for the colours of double stars. It was thus -presented by Professor Nichol, in a chapter of his “Architecture of the -Heavens,” on this special subject:—“The rapid motion of light reaches -indeed one of those numbers which reason owns, while imagination ceases -to comprehend them; but it is also true that the swiftness with which -certain individuals of the double stars sweep past their perihelias, -or rather their periasters, is amazing; and in this matter of colours, -it must be recollected that the question solely regards the difference -between the velocities of the waves constituent of colours, at those -different stellar positions. Still it is a bold—even a magnificent -idea; and if it can be reconciled with the permanent colours of the -multitude of stars surrounding us—stars which too are moving in great -orbits with immense velocities—it may be hailed almost as a positive -discovery. It must obtain confirmation, or otherwise, so soon as we -can compare with certainty the observed colorific changes of separate -systems with the known fluctuations of their orbital motions.” - -That was written a quarter of a century ago, when spectroscopic -analysis, as we now know it, had no existence. Accordingly, while the -fatal objection to Doppler’s original theory is overlooked on the -one hand, the means of applying the principle underlying the theory, -in a much more exact manner than Doppler could have hoped for, is -overlooked on the other. Both points are noted in the article above -referred to, in the same paragraph. “We may dismiss,” I there stated, -“the theory started some years ago by the French astronomer, M. -Doppler.” But, I presently added, “It is quite clear that the effects -of a motion rapid enough to produce such a change” (_i.e._ a change -of tint in a pure colour) “would shift the position of the whole -spectrum—and this change would be readily detected by a reference -to the spectral lines.” This is true, even to the word “readily.” -Velocities which would produce an appreciable change of tint would -produce “readily” detectible changes in the position of the spectral -lines; the velocities actually existing among the star-motions would -produce changes in the position of these lines detectible only with -extreme difficulty, or perhaps in the majority of instances not -detectible at all. - -It has been in this way that the spectroscopic method has actually been -applied. - -It is easy to perceive the essential difference between this way of -applying the method and that depending on the attempted recognition -of changes of colour. A dark line in the spectrum marks in reality -the place of a missing tint. The tints next to it on either side are -present, but the tint between them is wanting. They are changed in -colour—very slightly, in fact quite inappreciably—by motions of -recession or approach, or, in other words, they are shifted in position -along the spectrum, towards the red end for recession, towards the -violet end for approach; and of course the dark space between is -shifted along with them. One may say that the missing tint is changed. -For in reality that is precisely what would happen. If the light of -a star at rest gave every tint of the spectrum, for instance, except -mid-green alone, and that star approached or receded so swiftly that -its motion would change pure green light to pure yellow in one case, -or pure blue in the other, then the effect on the spectrum of such a -star would be to throw the dark line from the middle of the green part -of the spectrum to the middle of the yellow part in one case, or to -the middle of the blue part in the other. The dark line would be quite -notably shifted in either case. With the actual stellar motions, though -all the lines are more or less shifted, the displacement is always -exceedingly minute, and it becomes a task of extreme difficulty to -recognize, and still more to measure, such displacement. - -When I first indicated publicly (January, 1868) the way in which -Doppler’s principle could alone be applied, two physicists, Huggins -in England and Secchi in Italy, were actually endeavouring, with the -excellent spectroscopes in their possession, to apply this method. In -March, 1868, Secchi gave up the effort as useless, publicly announcing -the plan on which he had proceeded and his failure to obtain any -results except negative ones. A month later Huggins also publicly -announced the plan on which he had been working, but was also able -to state that in one case, that of the bright star Sirius, he had -succeeded in measuring a motion in the line of sight, having discovered -that Sirius was receding from the earth at the rate of 41·4 miles per -second. I say was receding, because a part of the recession at the time -of observation was due to the earth’s orbital motion around the sun. I -had, at his request, supplied Huggins with the formula for calculating -the correction due to this cause, and, applying it, he found that -Sirius is receding from the sun at the rate of about 29½ miles per -second, or some 930 millions of miles per annum. - -I am not here specially concerned to consider the actual results of the -application of this method since the time of Huggins’s first success; -but the next chapter of the history of the method is one so interesting -to myself personally that I feel tempted briefly to refer to details. -So soon as I had heard of Huggins’s success with Sirius, and that an -instrument was being prepared for him wherewith he might hope to extend -the method to other stars, I ventured to make a prediction as to the -result which he would obtain whensoever he should apply it to five -stars of the seven forming the so-called Plough. I had found reason -to feel assured that these five form a system drifting all together -amid stellar space. Satisfied for my own part as to the validity of -the evidence, I submitted it to Sir J. Herschel, who was struck by -its force. The apparent drift of those stars was, of course, a thwart -drift; but if they really were drifting in space, then their motions in -the line of sight must of necessity be alike. My prediction, then, was -that whensoever Huggins applied to those stars the new method he would -find them either all receding at the same rate, or all approaching at -the same rate, or else that all _alike_ failed to give any evidence at -all either of recession or approach. I had indicated the five in the -first edition of my “Other Worlds”—to wit, the stars of the Plough, -omitting the nearest “pointer” to the pole and the star marking the -third horse (or the tip of the Great Bear’s tail). So soon as Huggins’s -new telescope and its spectroscopic adjuncts were in working order, he -re-examined Sirius, determined the motions of other stars; and at last -on one suitable evening he tested the stars of the Plough. He began -with the nearest pointer, and found that star swiftly approaching the -earth. He turned to the other pointer, and found it rapidly receding -from the earth. Being under the impression that my five included both -pointers, he concluded that my prediction had utterly failed, and so -went on with his observations, altogether unprejudiced in its favour, -to say the least. The next star of the seven he found to be receding -at the same rate as the second pointer; the next at the same rate, -the next, and the next receding still at the same rate, and lastly -the seventh receding at a different rate. Here, then, were five stars -all receding at a common rate, and of the other two one receding at -a different rate, the other swiftly approaching. Turning next to the -work containing my prediction, Huggins found that the five stars thus -receding at a common rate were the five whose community of motion I -had indicated two years before. Thus the first prediction ever made -respecting the motions of the so-called fixed stars was not wanting in -success. I would venture to add that the theory of star-drift, on the -strength of which the prediction was made, was in effect demonstrated -by the result. - -The next application of the new method was one of singular interest. I -believe it was Mr. Lockyer who first thought of applying the method to -measure the rate of solar hurricanes as well as the velocities of the -uprush and downrush of vaporous matter in the atmosphere of the sun. -Another spectroscopic method had enabled astronomers to watch the rush -of glowing matter from the edge of the sun, by observing the coloured -flames and their motions; but by the new method it was possible to -determine whether the flames at the edge were swept by solar cyclones -carrying them from or towards the eye of the terrestrial observer, -and also to determine whether glowing vapours over the middle of the -visible disc were subject to motion of uprush, which of course would -carry them towards the eye, or of downrush, which would carry them -from the eye. The result of observations directed to this end was to -show that at least during the time when the sun is most spotted, solar -hurricanes of tremendous violence take place, while the uprushing and -downrushing motions of solar matter sometimes attain a velocity of more -than 100 miles per second. - -It was this success on the part of an English spectroscopist which -caused that attack on the new method against which it has but recently -been successfully defended, at least in the eyes of those who are -satisfied only by experimental tests of the validity of a process. -The Padre Secchi had failed, as we have seen, to recognize motions of -recession and approach among the stars by the new method. But he had -taken solar observation by spectroscopic methods under his special -charge, and therefore when the new results reached his ears he felt -bound to confirm or invalidate them. He believed that the apparent -displacement of dark lines in the solar spectrum might be due to the -heat of the sun causing changes in the delicate adjustments of the -instrument—a cause of error against which precautions are certainly -very necessary. He satisfied himself that when sufficient precautions -are taken no displacements take place such as Lockyer, Young, and -others claimed to have seen. But he submitted the matter to a further -test. As the sun is spinning swiftly on his axis, his mighty equator, -more than two and a half millions of miles in girth, circling once -round in about twenty-four days, it is clear that on one side the sun’s -surface is swiftly moving _towards_, and on the other side as swiftly -moving _from_, the observer. By some amazing miscalculation, Secchi -made the rate of this motion 20 miles per second, so that the sum of -the two motions in opposite directions would equal 40 miles per second. -He considered that he ought to be able by the new method, if the new -method is trustworthy at all, to recognize this marked difference -between the state of the sun’s eastern and western edges; he found on -trial that he could not do so; and accordingly he expressed his opinion -that the new method is not trustworthy, and that the arguments urged in -its favour are invalid. - -The weak point in his reasoning resided in the circumstance that the -solar equator is only moving at the rate of about 1¼ miles per second, -so that instead of a difference of 40 miles per second between the -two edges, which should be appreciable, the actual difference (that -is, the sum of the two equal motions in opposite directions) amounts -only to 2½ miles per second, which certainly Secchi could not hope to -recognize with the spectroscopic power at his disposal. Nevertheless, -when the error in his reasoning was pointed out, though he admitted -that error, he maintained the justice of his conclusion; just as -Cassini, having mistakenly reasoned that the degrees of latitude should -diminish towards the pole instead of increasing, and having next -mistakenly found, as he supposed, that they do diminish, acknowledged -the error of his reasoning, but insisted on the validity of his -observations,—maintaining thenceforth, as all the world knows, that -the earth is extended instead of flattened at the poles. - -Huggins tried to recognize by the new method the effects of the sun’s -rotation, using a much more powerful spectroscope than Secchi’s. The -history of the particular spectroscope he employed is in one respect -specially interesting to myself, as the extension of spectroscopic -power was of my own devising before I had ever used or even seen a -powerful spectroscope. The reader is aware that spectroscopes derive -their light-sifting power from the prisms forming them. The number -of prisms was gradually increased, from Newton’s single prism to -Fraunhofer’s pair, and to Kirchhoff’s battery of four, till six were -used, which bent the light round as far as it would go. Then the idea -occurred of carrying the light to a higher level (by reflections) -and sending it back through the same battery of prisms, doubling the -dispersion. Such a battery, if of six prisms, would spread the spectral -colours twice as widely apart as six used in the ordinary way, and -would thus have a dispersive power of twelve prisms. It occurred -to me that after taking the rays through six prisms, arranged in a -curve like the letter C, an intermediate four-cornered prism of a -particular shape (which I determined) might be made to send the rays -into another battery of six prisms, the entire set forming a double -curve like the letter S, the rays being then carried to a higher level -and back through the double battery. In this way a dispersive power of -nineteen prisms could be secured. My friend, Mr. Browning, the eminent -optician, made a double battery of this kind,[13] which was purchased -by Mr. W. Spottiswoode, and by him lent to Mr. Huggins for the express -purpose of dealing with the task Secchi had set spectroscopists. It -did not, however, afford the required evidence. Huggins considered -the displacement of dark lines due to the sun’s rotation to be -recognizable, but so barely that he could not speak confidently on the -point. - -There for a while the matter rested. Vögel made observations confirming -Huggins’s results relative to stellar motions; but Vögel’s instrumental -means were not sufficiently powerful to render his results of much -weight. - -But recently two well-directed attacks have been made upon this -problem, one in England, the other in America, and in both cases with -success. Rather, perhaps, seeing that the method had been attacked and -was supposed to require defence, we may say that two well-directed -assaults have been made upon the attacking party, which has been -completely routed. - -Arrangements were made not very long ago, by which the astronomical -work of Greenwich Observatory, for a long time directed almost -exclusively to time observations, should include the study of the sun, -stars, planets, and so forth. Amongst other work which was considered -suited to the National Observatory was the application of spectroscopic -analysis to determine motions of recession and approach among the -celestial bodies. Some of these observations, by the way, were made, we -are told, “to test the truth of Doppler’s principle,” though it seems -difficult to suppose for an instant that mathematicians so skilful as -the chief of the Observatory and some of his assistants could entertain -any doubt on that point. Probably it was intended by the words just -quoted to imply simply that some of the observations were made for the -purpose of illustrating the principle of the method. We are not to -suppose that on a point so simple the Greenwich observers have been in -any sort of doubt. - -At first their results were not very satisfactory. The difficulties -which had for a long time foiled Huggins, and which Secchi was never -able to master, rendered the first Greenwich measures of stellar -motions in the line of sight wildly inconsistent, not only with -Huggins’s results, but with each other. - -Secchi was not slow to note this. He renewed his objections to the new -method of observation, pointing and illustrating them by referring to -the discrepancies among the Greenwich results. But recently a fresh -series of results has been published, showing that the observers -at Greenwich have succeeded in mastering some at least among the -difficulties which they had before experienced. The measurements -of star-motions showed now a satisfactory agreement with Huggins’s -results, and their range of divergence among themselves was greatly -reduced. The chief interest of the new results, however, lay in the -observations made upon bodies known to be in motion in the line of -sight at rates already measured. These observations, though not wanted -as tests of the accuracy of the principle, were very necessary as tests -of the qualities of the instruments used in applying it. It is here and -thus that Secchi’s objections alone required to be met, and here and -thus they have been thoroughly disposed of. Let us consider what means -exist within the solar system for thus testing the new method. - -The earth travels along in her orbit at the rate of about 18⅓ miles -in every second of time. Not to enter into niceties which could only -properly be dealt with mathematically, it may be said that with this -full velocity she is at times approaching the remoter planets of the -system, and at times receding from them; so that here at once is a -range of difference amounting to about 37 miles per second, and fairly -within the power of the new method of observation. For it matters -nothing, so far as the new method is concerned, whether the earth is -approaching another orb by her motion, or that orb approaching by its -own motion. Again, the plant Venus travels at the rate of about 21½ -miles per second, but as the earth travels only 3 miles a second less -swiftly, and the same way round, only a small portion of Venus’s motion -ever appears as a motion of approach towards or recession from the -earth. Still, Venus is sometimes approaching and sometimes receding -from the earth, at a rate of more than 8 miles per second. Her light -is much brighter than that of Jupiter or Saturn, and accordingly this -smaller rate of motion would be probably more easily recognized than -the greater rate at which the giant planets are sometimes approaching -and at other times receding from the earth. At least, the Greenwich -observers seem to have confined their attention to Venus, so far as -motions of planets in the line of sight are concerned. The moon, as -a body which keeps always at nearly the same distance from us, would -of course be the last in the world to be selected to give positive -evidence in favour of the new method; but she serves to afford a useful -test of the qualities of the instruments employed. If when these were -applied to her they gave evidence of motions of recession or approach -at the rate of several miles per second, when we know as a matter of -fact that the moon’s distance never[14] varies by more than 30,000 -miles during the lunar month, her rate of approach or recession thus -averaging about one-fiftieth part of a mile per second, discredit -would be thrown on the new method—not, indeed, as regards its -principle, which no competent reasoner can for a moment question, but -as regards the possibility of practically applying it with our present -instrumental means. - -Observations have been made at Greenwich, both on Venus and on the -moon, by the new method, with results entirely satisfactory. The method -shows that Venus is receding when she is known to be receding, and -that she is approaching when she is known to be approaching. Again, -the method shows no signs of approach or recession in the moon’s case. -It is thus in satisfactory agreement with the known facts. Of course -these results are open to the objection that the observers have known -beforehand what to expect, and that expectation often deceives the -mind, especially in cases where the thing to be observed is not at all -easy to recognize. It will presently be seen that the new method has -been more satisfactorily tested, in this respect, in other ways. It may -be partly due to the effect of expectation that in the case of Venus -the motions of approach and recession, tested by the new method, have -always been somewhat too great. A part of the excess may be due to the -use of the measure of the sun’s distance, and therefore the measures -of the dimensions of the solar system, in vogue before the recent -transit. These measures fall short to some degree of those which result -from the observations made in December, 1874, on Venus in transit, the -sun’s distance being estimated at about 91,400,000 miles instead of -92,000,000 miles, which would seem to be nearer the real distance. Of -course all the motions within the solar system would be correspondingly -under-estimated. On the other hand, the new method would give all -velocities with absolute correctness if instrumental difficulties -could be overcome. The difference between the real velocities of Venus -approaching and receding, and those calculated according to the present -inexact estimate of the sun’s distance, is however much less than -the observed discrepancy, doubtless due to the difficulties involved -in the application of this most difficult method. I note the point, -chiefly for the sake of mentioning the circumstance that theoretically -the method affords a new means of measuring the dimensions of the -solar system. Whensoever the practical application of the method has -been so far improved that the rate of approach or recession of Venus, -or Mercury, or Jupiter, or Saturn (any one of these planets), can be -determined on any occasion, with great nicety, we can at once infer -the sun’s distance with corresponding exactness. Considering that -the method has only been invented ten years (setting aside Doppler’s -first vague ideas respecting it), and that spectroscopic analysis as a -method of exact observation is as yet little more than a quarter of -a century old, we may fairly hope that in the years to come the new -method, already successfully applied to measure motions of recession -and approach at the rate of 20 or 30 miles per second, will be employed -successfully in measuring much smaller velocities. Then will it give -us a new method of measuring the great base-line of astronomical -surveying—the distance of our world from the centre of the solar -system. - -That this will one day happen is rendered highly probable, in my -opinion, by the successes next to be related. - -Besides the motions of the planets around the sun, there are their -motions of rotation, and the rotation of the sun himself upon his -axis. Some among these turning motions are sufficiently rapid to be -dealt with by the new method. The most rapid rotational motion with -which we are acquainted from actual observation is that of the planet -Jupiter. The circuit of his equator amounts to about 267,000 miles, -and he turns once on his axis in a few minutes less than ten hours, so -that his equatorial surface travels at the rate of about 26,700 miles -an hour, or nearly 7½ miles per second. Thus between the advancing and -retreating sides of the equator there is a difference of motion in -the line of sight amounting to nearly 15 miles. But this is not all. -Jupiter shines by reflecting sunlight. Now it is easily seen that where -his turning equator _meets_ the waves of light from the sun, these are -shortened, in the same sense that waves are shortened for a swimmer -travelling to meet them, while these waves, already shortened in this -way, are further shortened when starting from the same advancing -surface of Jupiter, on their journey to us after reflection. In this -way the shortening of the waves is doubled, at least when the earth is -so placed that Jupiter lies in the same direction from us as from the -sun, the very time, in fact, when Jupiter is most favourably placed -for ordinary observation, or is at his highest due south, when the sun -is at his lowest below the northern horizon—that is, at midnight. -The lengthening of the waves is similarly doubled at this most -favourable time for observation; and the actual difference between the -motion of the two sides of Jupiter’s equator being nearly 15 miles -per second, the effect on the light-waves is equivalent to that due -to a difference of nearly 30 miles per second. Thus the new method -may fairly be expected to indicate Jupiter’s motion of rotation. The -Greenwich observers have succeeded in applying it, though Jupiter has -not been favourably situated for observation. Only on one occasion, -says Sir G. Airy, was the spectrum of Jupiter “seen fairly well,” -and on that occasion “measures were obtained which gave a result in -remarkable agreement with the calculated value.” It may well be hoped -that when in the course of a few years Jupiter returns to that part of -his course where he rises high above the horizon, shining more brightly -and through a less perturbed air, the new method will be still more -successfully applied. We may even hope to see it extended to Saturn, -not merely to confirm the measures already made of Saturn’s rotation, -but to resolve the doubts which exist as to the rotation of Saturn’s -ring-system. - -Lastly, there remains the rotation of the sun, a movement much more -difficult to detect by the new method, because the actual rate of -motion even at the sun’s equator amounts only to about 1 mile per -second. - -In dealing with this very difficult task, the hardest which -spectroscopists have yet attempted, the Greenwich observers have -achieved an undoubted success; but unfortunately for them, though -fortunately for science, another observatory, far smaller and of much -less celebrity, has at the critical moment achieved success still more -complete. - -The astronomers at our National Observatory have been able to recognize -by the new method the turning motion of the sun upon his axis. And -here we have not, as in the case of Venus, to record merely that the -observers have seen what they expected to see because of the known -motion of the sun. “Particular care was taken,” says Airy, “to -avoid any bias from previous knowledge of the direction in which a -displacement” (of the spectral lines) “was to be expected,” the side of -the sun under observation not being known by the observer until after -the observation was completed. - -But Professor Young, at Dartmouth College, Hanover, N.H., has done much -more than merely obtain evidence by the new method that the sun is -rotating as we already knew. He has succeeded so perfectly in mastering -the instrumental and observational difficulties, as absolutely to be -able to rely on his _measurement_ (as distinguished from the mere -recognition) of the sun’s motion of rotation. The manner in which he -has extended the powers of ordinary spectroscopic analysis, cannot very -readily be described in these pages, simply because the principles on -which the extension depends require for their complete description a -reference to mathematical considerations of some complexity. Let it be -simply noted that what is called the diffraction spectrum, obtained -by using a finely lined plate, results from the dispersive action -of such a plate, or _grating_ as it is technically called, and this -dispersive power can be readily combined with that of a spectroscope -of the ordinary kind. Now Dr. Rutherfurd, of New York, has succeeded -in ruling so many thousand lines on glass within the breadth of a -single inch as to produce a grating of high dispersive power. Availing -himself of this beautiful extension of spectroscopic powers, Professor -Young has succeeded in recognizing effects of much smaller motions -of recession and approach than had before been observable by the new -method. He has thus been able to measure the rotation-rate of the sun’s -equatorial regions. His result exceeds considerably that inferred from -the telescopic observation of the solar spots. For whereas from the -motion of the spots a rotation-rate of about 1¼ mile per second has -been calculated for the sun’s equator, Professor Young obtains from his -spectroscopic observations a rate of rather more than 1⅖ mile, or about -300 yards per second more than the telescopic rate. - -If Young had been measuring the motion of the same matter which is -observed with the telescope, there could of course be no doubt that -the telescope was right and the spectroscope wrong. We might add a -few yards per second for the probably greater distance of the sun -resulting from recent transit observations. For of course with an -increase in our estimate of the sun’s distance there comes an increase -in our estimate of the sun’s dimensions, and of the velocity of the -rotational motion of his surface. But only about 12 yards per second -could be allowed on this account; the rest would have to be regarded -as an error due to the difficulties involved in the spectroscopic -method. In reality, however, the telescopist and the spectroscopist -observe different things in determining by their respective methods -the sun’s motion of rotation. The former observes the motion of the -spots belonging to the sun’s visible surface; the latter observes the -motion of the glowing vapours outside that surface, for it is from -these vapours, not from the surface of the sun, that the dark lines -of the spectrum proceed. Now so confident is Professor Young of the -accuracy of his spectroscopic observations, that he is prepared to -regard the seeming difference of velocity between the atmosphere and -surface of the sun as real. He believes that “the solar atmosphere -really sweeps forward over the underlying surface, in the same way -that the equatorial regions outstrip the other parts of the sun’s -surface.” This inference, important and interesting in itself, is far -more important in what it involves. For if we can accept it, it follows -that the spectroscopic method of measuring the velocity of motions in -the line of sight is competent, under favourable conditions, to obtain -results accurate within a few hundred yards per second, or 10 or 12 -miles per minute. If this shall really prove to be true for the method -now, less than ten years after it was first successfully applied, -what may we not hope from the method in future years? Spectroscopic -analysis itself is in its infancy, and this method is but a recent -application of spectroscopy. A century or so hence astronomers will -smile (though not disdainfully) at these feeble efforts, much as we -smile now in contemplating the puny telescopes with which Galileo and -his contemporaries studied the star-depths. And we may well believe -that largely as the knowledge gained by telescopists in our own -time surpasses that which Galileo obtained, so will spectroscopists -a few generations hence have gained a far wider and deeper insight -into the constitution and movements of the stellar universe than the -spectroscopists of our own day dare even hope to attain. - -I venture confidently to predict that, in that day, astronomers will -recognize in the universe of stars a variety of structure, a complexity -of arrangement, an abundance of every form of cosmical vitality, such -as I have been led by other considerations to suggest, not the mere -cloven lamina of uniformly scattered stars more or less resembling our -sun, and all in nearly the same stage of cosmical development, which -the books of astronomy not many years since agreed in describing. The -history of astronomical progress does not render it probable that the -reasoning already advanced, though in reality demonstrative, will -convince the generality of science students until direct and easily -understood observations have shown the real nature of the constitution -of that part of the universe over which astronomical survey extends. -But the evidence already obtained, though its thorough analysis may -be “_caviare_ to the general,” suffices to show the real nature of -the relations which one day will come within the direct scope of -astronomical observation. - - - - -_THE NEW STAR WHICH FADED INTO STAR-MIST._ - - -The appearance of a new star in the constellation of the Swan in the -autumn of 1876 promises to throw even more light than was expected on -some of the most interesting problems with which modern astronomy has -to deal. It was justly regarded as a circumstance of extreme interest -that so soon after the outburst of the star which formed a new gem -in the Northern Crown in May, 1866, another should have shone forth -under seemingly similar conditions. And when, as time went on, it -appeared that in several respects the new star in the Swan differed -from the new star in the Crown, astronomers found fresh interest in -studying, as closely as possible, the changes presented by the former -as it gradually faded from view. But they were not prepared to expect -what has actually taken place, or to recognize so great a difference -of character between these two new stars, that whereas one seemed -throughout its visibility to ordinary eyesight, and even until the -present time, to be justly called a star, the other should so change as -to render it extremely doubtful whether at any time it deserved to be -regarded as a star or sun. - -Few astronomical phenomena, even of those observed during this century -(so fruitful in great astronomical discoveries), seem better worthy -of thorough investigation and study than those presented by the two -stars which appeared in the Crown and in the Swan, in 1866 and 1876 -respectively. A new era seems indeed to be beginning for those -departments of astronomy which deal with stars and star-cloudlets on -the one hand, and with the evolution of solar systems and stellar -systems on the other. - -Let us briefly consider the history of the star of 1866 in the first -place, and then turn our thoughts to the more surprising and probably -more instructive history of the star which shone out in November, 1876. - -In the first place, however, I would desire to make a few remarks -on the objections which have been expressed by an observer to whom -astronomy is indebted for very useful work, against the endeavour to -interpret the facts ascertained respecting these so-called new stars. -M. Cornu, who made some among the earliest spectroscopic observations -of the star in Cygnus, after describing his results, proceeded as -follows:—“Grand and seductive though the task may be of endeavouring -to draw from observed facts inductions respecting the physical state of -this new star, respecting its temperature, and the chemical reactions -of which it may be the scene, I shall abstain from all commentary and -all hypothesis on this subject. I think that we do not yet possess -the data necessary for arriving at useful conclusions, or at least at -conclusions capable of being tested: however attractive hypotheses may -be, we must not forget that they are outside the bounds of science, -and that, far from serving science, they seriously endanger its -progress.” This, as I ventured to point out at the time, is utterly -inconsistent with all experience. M. Cornu’s objection to theorizing -when he did not see his way to theorizing justly, is sound enough; -but his general objection to theorizing is, with all deference be it -said, sheerly absurd. It will be noticed that I say theorizing, not -hypothesis-framing; for though he speaks of hypotheses, he in reality -is describing theories. The word hypothesis is too frequently used in -this incorrect sense—perhaps so frequently that we may almost prefer -sanctioning the use to substituting the correct word. But the fact -really is, that many, even among scientific writers, when they hear -the word hypothesis, think immediately of Newton’s famous “hypotheses -non fingo,” a dictum relating to real hypotheses, not to theories. It -would, in fact, be absurd to suppose that Newton, who had advanced, -advocated, and eventually established, the noblest scientific theory -the world has known, would ever have expressed an objection to -theorizing, as he is commonly understood to have done by those who -interpret his “hypotheses non fingo” in the sense which finds favour -with M. Cornu. But apart from this, Newton definitely indicates what he -means by hypotheses. “I frame no hypotheses,” he says, “_for whatever -is not deduced from phenomena is to be called an hypothesis_.” M. -Cornu, it will be seen, rejects the idea of deducing from phenomena -what he calls an hypothesis, but what would not be an hypothesis -according to Newton’s definition: “Malgré tout ce qu’il y aurait de -séduisant et de grandiose à tirer de ce fait des inductions, etc., je -m’abstiendrai de tout commentaire et de toute hypothèse à ce sujet.” It -is not thus that observed scientific facts are to be made fruitful, nor -thus that the points to which closer attention must be given are to be -ascertained. - -Since the preceding paragraph was written, my attention has been -attracted to the words of another observer more experienced than M. -Cornu, who has not only expressed the same opinion which I entertain -respecting M. Cornu’s ill-advised remark, but has illustrated in a -very practical way, and in this very case, how science gains from -commentary and theory upon observed facts. Herr Vögel considers “that -the fear that an hypothesis” (he, also, means a theory here) “might do -harm to science is only justifiable in very rare cases: in most cases -it will further science. In the first place, it draws the attention of -the observer to things which but for the hypothesis might have been -neglected. Of course if the observer is so strongly influenced that -in favour of an hypothesis he sees things which do not exist—and -this may happen sometimes—science may for a while be arrested in its -progress, but in that case the observer is far more to blame than -the author of the hypothesis. On the other hand, it is very possible -that an observer may, involuntarily, arrest the progress of science, -even without originating an hypothesis, by pronouncing and publishing -sentences which have a tendency to diminish the general interest in a -question, and which do not place its high significance in the proper -light.” (This is very neatly put.) He is “almost inclined to think that -such an effect might follow from the reading of M. Cornu’s remark, and -that nowhere better than in the present case, where in short periods -colossal changes showed themselves occurring upon a heavenly body, -might the necessary data be obtained for drawing useful conclusions, -and tests be applied to those hypotheses which have been ventured -with regard to the condition of heavenly bodies.” It was, as we shall -presently see, in thus collecting data and applying tests, that Vögel -practically illustrated the justice of his views. - -The star which shone out in the Northern Crown in May, 1866, would seem -to have grown to its full brightness very quickly. It is not necessary -that I should here consider the history of the star’s discovery; but -I think all who have examined that history agree in considering that -whereas on the evening of May 12, 1866, a new star was shining in the -Northern Crown with second-magnitude brightness, none had been visible -in the same spot with brightness above that of a fifth-magnitude -star twenty-four hours earlier. On ascertaining, however, the place -of the new star, astronomers found that there had been recorded in -Argelander’s charts and catalogue a star of between the ninth and tenth -magnitude in this spot. The star declined very rapidly in brightness. -On May 13th it appeared of the third magnitude; on May 16th it had -sunk to the fourth magnitude; on the 17th to the fifth; on the 19th to -the seventh; and by the end of the month it shone only as a telescopic -star of the ninth magnitude. It is now certainly not above the tenth -magnitude. - -Examined with the spectroscope, this star was found to be in an -abnormal condition. It gave the rainbow-tinted streak crossed by dark -lines, which is usually given by stars (with minor variations, which -enable astronomers to classify the stars into several distinct orders). -But superposed upon this spectrum, or perhaps we should rather say -shining through this spectrum, were seen four brilliant lines, two -of which certainly belonged to glowing hydrogen. These lines were so -bright as to show that the greater part of the light of the star at -the time came from the glowing gas or gases giving these lines. It -appeared, however, that the rainbow-tinted spectrum on which these -lines were seen was considerably brighter than it would otherwise have -been, in consequence of the accession of heat indicated by and probably -derived from the glowing hydrogen. - -Unfortunately, we have not accordant accounts of the changes which the -spectrum of this star underwent as the star faded out of view. Wolf -and Rayet, of the Paris Observatory, assert that when there remained -scarcely any trace of the continuous spectrum, the four bright lines -were still quite brilliant. But Huggins affirms that this was not the -case in his observations; he was “able to see the continuous spectrum -when the bright lines could be scarcely distinguished.” As the bright -lines certainly faded out of view eventually, we may reasonably assume -that the French observers were prevented by the brightness of the lines -from recognizing the continuous spectrum at that particular stage of -the diminution of the star’s light when the continuous spectrum had -faded considerably but the hydrogen lines little. Later, the continuous -spectrum ceased to diminish in brightness, while the hydrogen lines -rapidly faded. Thereafter the continuous spectrum could be discerned, -and with greater and greater distinctness as the hydrogen lines faded -out. - -Now, in considering the meaning of the observed changes in the -so-called “new star,” we have two general theories to consider. - -One of these theories is that to which Dr. Huggins would seem to have -inclined, though he did not definitely adopt it—the theory, namely, -that in consequence of some internal convulsion enormous quantities of -hydrogen and other gases were evolved, which in combining with some -other elements ignited on the surface of the star, and thus enveloped -the whole body suddenly in a sheet of flame. - -“The ignited hydrogen gas in burning produced the light corresponding -to the two bright bands in the red and green; the remaining bright -lines were not, however, coincident with those of oxygen, as might have -been expected. According to this theory, the burning hydrogen must have -greatly increased the heat of the solid matter of the photosphere and -brought it into a state of more intense incandescence and luminosity, -which may explain how the formerly faint star could so suddenly assume -such remarkable brilliance; the liberated hydrogen became exhausted, -the flame gradually abated, and with the consequent cooling the -photosphere became less vivid, and the star returned to its original -condition.” - -According to the other theory, advanced by Meyer and Klein, the -blazing forth of this new star may have been occasioned by the violent -precipitation of some great mass, perhaps a planet, upon a fixed star, -“by which the momentum of the falling mass would be changed into -molecular motion,” and result in the emission of light and heat. - -“It might even be supposed that the new star, through its rapid motion, -may have come in contact with one of the nebulæ which traverse in great -numbers the realms of space in every direction, and which from their -gaseous condition must possess a high temperature; such a collision -would necessarily set the star in a blaze, and occasion the most -vehement ignition of its hydrogen.” - -If we regard these two theories in their more general aspect, -considering one as the theory that the origin of disturbance was within -the star, and the other as the theory that the origin of disturbance -was outside the star, they seem to include all possible interpretations -of the observed phenomena. But, as actually advanced, neither seems -satisfactory. The sudden pouring forth of hydrogen from the interior, -in quantities sufficient to explain the outburst, seems altogether -improbable. On the other hand, as I have pointed out elsewhere, there -are reasons for rejecting the theory that the cause of the heat which -suddenly affected this star was either the downfall of a planet on -the star or the collision of the star with a star-cloudlet or nebula, -traversing space in one direction, while the star rushed onwards in -another. - -A planet could not very well come into final conflict with its sun at -one fell swoop. It would gradually draw nearer and nearer, not by the -narrowing of its path, but by the change of the path’s shape. The path -would, in fact, become more and more eccentric; until at length, at its -point of nearest approach, the planet would graze its primary, exciting -an intense heat where it struck, but escaping actual destruction that -time. The planet would make another circuit, and again graze the sun, -at or near the same part of the planet’s path. For several circuits -this would continue, the grazes not becoming more and more effective -each time, but rather less. The interval between them, however, would -grow continually less and less; at last the time would come when -the planet’s path would be reduced to the circular form, its globe -touching the sun’s all the way round, and then the planet would very -quickly be reduced to vapour and partly burned up, its substance being -absorbed by its sun. But all successive grazes would be indicated to -us by accessions of lustre, the period between each seeming outburst -being only a few months at first, and gradually becoming less and less -(during a long course of years, perhaps even of centuries) until the -planet was finally destroyed. Nothing of this sort has happened in the -case of any so-called new star. As for the rush of a star through a -nebulous mass, that is a theory which would scarcely be entertained by -any one acquainted with the enormous distances separating the gaseous -star-clouds properly called nebulæ. There may be small clouds of the -same sort scattered much more freely through space; but we have not a -particle of evidence that this is actually the case. All we certainly -_know_ about star-cloudlets suggests that the distances separating them -from each other are comparable with those which separate star from -star, in which case the idea of a star coming into collision with a -star-cloudlet, and still more the idea of this occurring several times -in a century, is wild in the extreme. - -But while thus advancing objections, which seem to me irrefragable, -against the theory that either a planet or a nebula (still less another -small star) had come into collision with the orb in Corona which shone -out so splendidly for a while, I advanced another view which seemed -to me then and seems now to correspond well with phenomena, and to -render the theory of action from without on the whole preferable to the -theory of outburst from within. I suggested that, far more probably, -an enormous flight of large meteoric masses travelling around the -star had come into partial collision with it in the same way that the -flight of November meteors comes into collision with our earth thrice -in each century, and that other meteoric flights may occasionally come -into collision with our sun, producing the disturbances which occasion -the sun-spots. As I pointed out, in conceiving this we are imagining -nothing new. A meteoric flight capable of producing the suggested -effects would differ only in kind from meteoric flights which are known -to circle around our own sun. The meteors which produce the November -displays of falling stars follow in the track of a comet barely visible -to the naked eye. - -“May we not reasonably assume that those glorious comets which have not -only been visible but conspicuous, shining even in the day-time, and -brandishing around tails, which like that of the ‘wonder in heaven, the -great dragon,’ seemed to ‘draw the third part of the stars of heaven,’ -are followed by much denser flights of much more massive meteors? -Some of these giant comets have paths which carry them very close to -our sun. Newton’s comet, with its tail a hundred millions of miles in -length, all but grazed the sun’s globe. The comet of 1843, whose tail, -says Sir John Herschel, ‘stretched half-way across the sky,’ must -actually have grazed the sun, though but lightly, for its nucleus was -within 80,000 miles of his surface, and its head was more than 160,000 -miles in diameter. And these are only two among the few comets whose -paths are known. At any time we might be visited by a comet mightier -than either, travelling in an orbit intersecting the sun’s surface, -followed by flights of meteoric masses enormous in size and many in -number, which, falling on the sun’s globe with enormous velocity -corresponding to their vast orbital range and their near approach to -the sun—a velocity of some 360 miles per second—would, beyond all -doubt, excite his whole frame, and especially his surface regions, to a -degree of heat far exceeding what he now emits.” - -This theory corresponds far better also with observed facts than the -theory of Meyer and Klein, in other respects than simply in antecedent -probability. It can easily be shown that if a planet fell upon a -sun in such sort as to become part of his mass, or if a nebula in a -state of intense heat excited the whole frame of a star to a similar -degree of heat, the effects would be of longer duration than the -observed accession of heat and light in the case of all the so-called -“new stars.” It has been calculated by Mr. Croll (the well-known -mathematician to whom we owe the most complete investigations yet made -into the effect of the varying eccentricity of the earth’s orbit on the -climate of the earth) that if two suns, each equal in mass to one-half -of our sun, came into collision with a velocity of 476 miles per -second, light and heat would be produced which would cover the present -rate of the sun’s radiation for fifty million years. Now although it -certainly does not follow from this that such a collision would result -in the steady emission of so much light and heat as our sun gives out, -for a period of fifty million years, but is, on the contrary, certain -that there would be a far greater emission at first and a far smaller -emission afterwards, yet it manifestly must be admitted that such a -collision could not possibly produce so short-lived an effect as we see -in the case of every one of the so-called new stars. The diminution -in the emission of light and heat from the maximum to one-half the -maximum would not occupy fifty millions of years, or perhaps even five -million or five hundred thousand years; but it would certainly require -thousands of years; whereas we have seen that the new stars in the -Crown and in the Swan have lost not one-half but ninety-nine hundredths -of their maximum lustre in a few months. - -This has been urged as an objection even to the term star as applied to -these suddenly appearing orbs. But the objection is not valid; because -there is no reason whatever for supposing that even our own sun might -not be excited by the downfall of meteoric or cometic matter upon it -to a sudden and short-lasting intensity of splendour and of heat. Mr. -Lockyer remarks that, if any star, properly so called, were to become -a “a world on fire,” or “burst into flames,” or, in less poetical -language, were to be driven either into a condition of incandescence -absolutely, or to have its incandescence increased, there can be little -doubt that thousands or millions of years would be necessary for the -reduction of its light to its original intensity. This must, however, -have been written in forgetfulness of some facts which have been -ascertained respecting our sun, and which indicate pretty clearly that -the sun’s surface might be roused to a temporary intensity of splendour -and heat without any corresponding increase in the internal heat, or in -the activity of the causes, whatever they may be, to which the sun’s -_steady_ emissions of light and heat are due. - -For instance, most of my readers are doubtless familiar with the -account (an oft-told tale, at any rate) of the sudden increase in -the splendour of a small portion of the sun’s surface on September -1, 1859, observed by two astronomers independently. The appearances -described corresponded exactly with what we should expect if two large -meteoric masses travelling side by side had rushed, with a velocity -originally amounting to two or three hundred miles per second, through -the portions of the solar atmosphere lying just above, at, and just -below the visible photosphere. The actual rate of motion was measured -at 120 miles per second as the minimum, but may, if the direction of -motion was considerably inclined to the line of sight, have amounted -to more than 200 miles per second. The effect was such, that the parts -of the sun thus suddenly excited to an increased emission of light and -heat appeared like bright stars upon the background of the glowing -photosphere itself. One of the observers, Carrington, supposed for a -moment that the dark glass screen used to protect the eye had broken. -The increase of splendour was exceedingly limited in area, and lasted -only for a few minutes—fortunately for the inhabitants of earth. As -it was, the whole frame of the earth sympathized with the sun. Vivid -auroras were seen, not only in both hemispheres, but in latitudes where -auroras are seldom seen. They were accompanied by unusually great -electro-magnetic disturbances. - -“In many places,” says Sir J. Herschel, “the telegraph wires struck -work. At Washington and Philadelphia, the electric signalmen received -severe electric shocks. At a station in Norway, the telegraphic -apparatus was set fire to, and at Boston, in North America, a flame of -fire followed the pen of Bain’s electric telegraph, which writes down -the message upon chemically prepared paper.” - -We see, then, that most certainly the sun can be locally excited to -increased emission of light and heat, which nevertheless may last but -for a very short time; and we have good reason for believing that the -actual cause of the sudden change in his condition was the downfall -of meteoric matter upon a portion of his surface. We may well believe -that, whatever the cause may have been, it was one which might in the -case of other suns, or even in our sun’s own case, affect a much larger -portion of the photosphere. If this happened there would be just -such an accession of splendour as we recognize in the case of the new -stars. And as the small local accession of brilliancy lasted only a few -minutes, we can well believe that an increase of surface brilliancy -affecting a much larger portion of the photosphere, or even the entire -photosphere, might last but for a few days or weeks. - -All that can be said in the way of negative evidence, so far as our -own sun is concerned, is that we have no reason for believing that -our sun has, at any time within many thousands of years, been excited -to emit even for a few hours a much greater amount of light and heat -than usual; so that it has afforded no direct evidence in favour of -the belief that other suns may be roused to many times their normal -splendour, and yet very quickly resume that usual lustre. But we know -that our sun, whether because of his situation in space, or of his -position in time (that is, the stage of solar development to which he -has at present attained), belongs to the class of stars which shine -with steady lustre. He does not vary like Betelgeux, for example, which -is not only a sun like him as to general character, but notably a -larger and more massive orb. Still less is he like Mira, the Wonderful -Star; or like that more wonderful variable star, Eta Argûs, which at -one time shines with a lustre nearly equalling that of the bright -Sirius, and anon fades away almost into utter invisibility. He _is_ a -variable sun, for we cannot suppose that the waxing and waning of the -sun-spot period leaves his lustre, as a whole, altogether unaffected. -But his variation is so slight that, with all ordinary methods of -photometric measurement by observers stationed on worlds which circle -around other suns, it must be absolutely undiscernible. We do not, -however, reject Betelgeux, or Mira, or even Eta Argûs, from among stars -because they vary in lustre. We recognize the fact that, as in glory, -so in condition and in changes of condition, one star differeth from -another. - -Doubtless there are excellent reasons for rejecting the theory that a -massive body like a planet, or a nebulous mass like those which are -found among the star-depths (the least of which would exceed many -times in volume a sphere filling the entire space of the orbit of -Neptune), fell on some remote sun in the Northern Crown. But there are -no sufficient reasons for rejecting or even doubting the theory that -a comet, bearing in its train a flight of many millions of meteoric -masses, falling directly upon such a sun, might cause it to shine -with many times its ordinary lustre, but only for a short time, a few -months or weeks, or a few days, or even hours. In the article entitled -“Suns in Flames,” in my “Myths and Marvels of Astronomy,” before the -startling evidence recently obtained from the star in Cygnus had -been thought of, I thus indicated the probable effects of such an -event:—“When the earth has passed through the richer portions (not the -actual nuclei be it remembered) of meteor systems, the meteors visible -from even a single station have been counted by tens of thousands, and -it has been computed that millions must have fallen upon the whole -earth. These were meteors following in the trains of very small comets. -If a very large comet followed by no denser a flight of meteors, but -each meteoric mass much larger, fell directly upon the sun, it would -not be the outskirts but the nucleus of the meteoric train which would -impinge upon him. They would number thousands of millions. The velocity -of downfall of each mass would be more than 360 miles per second. And -they would continue to pour in upon him for several days in succession, -millions falling every hour. It seems not improbable that under this -tremendous and long-continued meteoric hail, his whole surface would -be caused to glow as intensely as that small part whose brilliancy -was so surprising in the observation made by Carrington and Hodgson. -In that case our sun, seen from some remote star whence ordinarily he -is invisible, would shine out as a new sun for a few days, while all -things living, on our earth and whatever other members of the solar -system are the abodes of life, would inevitably be destroyed.” - -There are, indeed, reasons for believing, not only, as I have already -indicated, that the outburst in the sun was caused by the downfall of -meteoric masses, but that those masses were following in the train of -a known comet, precisely as the November meteors follow in the train of -Tempel’s comet (II., 1866). For we know that November meteoric displays -have been witnessed for five or six years after the passage of Tempel’s -comet, in its thirty-three year orbit, while the August meteoric -displays have been witnessed fully one hundred and twenty years -after the passage of their comet (II., 1862).[15] Now only sixteen -years before the solar outburst witnessed by Carrington and Hodgson, -a magnificent comet had passed even closer to the sun than either -Tempel’s comet or the second comet of 1862 approached the earth’s -orbit. That was the famous comet of the year 1843. Many of us remember -that wonderful object. I was but a child myself when it appeared, but -I can well remember its amazing tail, which in March, 1843, stretched -half-way across the sky. - -“Of all the comets on record,” says Sir J. Herschel, “that approached -nearest the sun; indeed, it was at first supposed that it had actually -grazed the sun’s surface, but it proved to have just missed by an -interval of not more than 80,000 miles—about a third of the distance -of the moon from the earth, which (in such a matter) is a very close -shave indeed to get clear off.” - -We can well believe that the two meteors which produced the remarkable -outburst of 1859 may have been stragglers from the main body following -after that glorious comet. I do not insist upon the connection. In -fact, I rather incline to the belief that the disturbance in 1859, -occurring as it did about the time of maximum sun-spot frequency, was -caused by meteors following in the train of some as yet undiscovered -comet, circuiting the sun in about eleven years, the spots themselves -being, I believe, due in the main to meteoric downfalls. There is -greater reason for believing that the great sun-spot which appeared -in June, 1843, was caused by the comet which three months before had -grazed the sun’s surface. As Professor Kirkwood, of Bloomington, -Indiana, justly remarks, had this comet approached a little nearer, -the resistance of the solar atmosphere would probably have brought -the comet’s entire mass to the solar surface. Even at its actual -distance, it must have produced considerable atmospheric disturbance. -But the recent discovery that a number of comets are associated -with meteoric matter travelling in nearly the same orbits, suggests -the inquiry whether an enormous meteorite following in the comet’s -train, and having a somewhat less perihelion distance, may not have -been precipitated upon the sun, thus producing the great disturbance -observed so shortly after the comet’s perihelion passage. - -Let us consider now the evidence obtained from the star in Cygnus, -noting especially in what points it resembles, and in what points it -differs from, the evidence afforded by the star in the Crown. - -The new star was first seen by Professor Schmidt at a quarter to six -on the evening of November 24. It was then shining as a star of the -third magnitude, in the constellation of the Swan, not very far from -the famous but faint star 61 Cygni—which first of all the stars in the -northern heavens had its distance determined by astronomers. The three -previous nights had unfortunately been dark; but Schmidt is certain -that on November 20 the star was not visible. At midnight, November -24, its light was very yellow, and it was somewhat brighter than the -well-known star Eta Pegasi, which marks the forearm of the Flying -Horse. Schmidt sent news of the discovery to Leverrier, at Paris; -but neither he nor Leverrier telegraphed the news, as they should -have done, to Greenwich, Berlin, or the United States. Many precious -opportunities for observing the spectrum of the new-comer at the time -of its greatest brilliancy were thus lost. - -The observers at Paris did their best to observe the spectrum of the -star and the all-important changes in the spectrum. But they had -unfavourable weather. It was not till December 2 that the star was -observed at Paris, by which time the colour, which had been very yellow -on November 24, had become “greenish, almost blue.” The star had also -then sunk from the third to far below the fourth magnitude. It is -seldom that science has to regret a more important loss of opportunity -than this. What we want specially to know is the nature of the spectrum -given by this star when its light was yellow; and this we can now never -know. Nor are the outbursts of new stars so common that we may quickly -expect another similar opportunity, even if any number of other new -stars should present the same series of phenomena as the star in Cygnus. - -On December 2, the spectrum, as observed by M. Cornu, consisted almost -entirely of bright lines. On December 5, he determined the position of -these lines, though clouds still greatly interfered with his labours. -He found three bright lines of hydrogen, the strong double sodium line -in the orange-yellow, the triple magnesium line in the yellow-green, -and two other lines—one of which seemed to agree exactly in position -with a bright line belonging to the solar corona. All these lines were -shining upon the rainbow-tinted background of the spectrum, which was -relatively faint. He drew the conclusion that in chemical constitution -the atmosphere of the new star was constituted exactly like the solar -sierra. - -Herr Vögel’s observations commenced on December 5, and were continued -at intervals until March 10, when the star had sunk to below the eighth -magnitude. - -Vögel’s earlier observations agreed well with Cornu’s. He remarks, -however, that Cornu’s opinion as to the exact resemblance of the -chemical constitution of the star’s atmosphere with that of the sierra -is not just, for both Cornu and himself noticed one line which did not -correspond with any line belonging to the solar sierra; and this line -eventually became the brightest line of the whole spectrum. Comparing -his own observations with those of Cornu, Vögel points out that they -agree perfectly with regard to the presence of the three hydrogen -lines, and that of the brightest line of the air spectrum (belonging to -nitrogen),—which is the principal line of the spectrum of nebulæ. This -is the line which has no analogue in the spectrum of the sierra. - -We have also observations by F. Secchi, at Rome, Mr. Copeland, at -Dunecht, and Mr. Backhouse, of Sunderland, all agreeing in the main -with the observations made by Vögel and Cornu. In particular, Mr. -Backhouse observed, as Vögel had done, that whereas in December the -greenish-blue line of hydrogen, F, was brighter than the nitrogen line -(also in the green-blue, but nearer the red end than F), on January 6 -the nitrogen line was the brightest of all the lines in the spectrum of -the new star. - -Vögel, commenting on the results of his observations up to March 10, -makes the following interesting remarks (I quote, with slight verbal -alterations, from a paraphrase in a weekly scientific journal):—“A -stellar spectrum with _bright_ lines is always a highly interesting -phenomenon for any one acquainted with stellar spectrum analysis, -and well worthy of deep consideration. Although in the chromosphere -(sierra) of our sun, near the limb, we see numerous bright lines, yet -only dark lines appear in the spectrum whenever we produce a small -star-like image of the sun, and examine it through the spectroscope. It -is generally believed that the bright lines in some few star-spectra -result from gases which break forth from the interior of the luminous -body, the temperature of which is higher than that of the surface of -the body—that is, the phenomenon is the same sometimes observed in -the spectra of solar spots, where incandescent hydrogen rushing out -of the hot interior becomes visible above the cooler spots through -the hydrogen lines turning bright. But this is not the only possible -explanation. We may also suppose that the atmosphere of a star, -consisting of incandescent gases, as is the case with our own sun, is -on the whole cooler than the nucleus, but with regard to the latter is -extremely large. I cannot well imagine how the phenomenon can last for -any long period of time if the former hypothesis be correct. The gas -breaking forth from the hot interior of the body will impart a portion -of its heat to the surface of the body, and thus raise the temperature -of the latter; consequently, the difference of temperature between the -incandescent gas and the surface of the body will soon be insufficient -to produce bright lines; and these will disappear from the spectrum. -This view applies perfectly to stars which suddenly appear and soon -disappear again, or at least increase considerably in intensity—that -is, it applies perfectly to so-called new stars in the spectra of -which bright lines are apparent, _if_ the hypothesis presently to be -mentioned is admitted for their explanation. For a more stable state -of things the second hypothesis seems to be far better adapted. Stars -like Beta Lyræ, Gamma Cassiopeiæ, and others, which show the hydrogen -lines and the sierra D line bright on a continuous spectrum, with -only slight changes of intensity, possess, according to this theory, -atmospheres very large relatively to their own volume—the atmospheres -consisting of hydrogen and that unknown element which produces the -D line.[16] With regard to the new star, Zöllner, long before the -progress lately made in stellar physics by means of spectrum analysis, -deduced from Tycho’s observations of the star called after him, that -on the surface of a star, through the constant emission of heat, the -products of cooling, which in the case of our sun we call sun-spots, -accumulate: so that finally the whole surface of the body is covered -with a colder stratum, which gives much less light or none at all. -Through a sudden and violent tearing up of this stratum, the interior -incandescent materials which it encloses must naturally break forth, -and must in consequence, according to the extent of their eruption, -cause larger or smaller patches of the dark envelope of the body to -become luminous again. To a distant observer such an eruption from the -hot and still incandescent interior of a heavenly body must appear as -the sudden flashing-up of a new star. That this evolution of light -may under certain conditions be an extremely powerful one, could be -explained by the circumstance that all the chemical compounds which, -under the influence of a lower temperature, had already formed upon the -surface, are again decomposed through the sudden eruption of these hot -materials; and that this decomposition, as in the case of terrestrial -substances, takes place under evolution of light and heat. Thus the -bright flashing-up is not only ascribed to the parts of the surface -which through the eruption of the incandescent matter have again become -luminous, but also to a simultaneous process of combustion, which is -initiated through the colder compounds coming into contact with the -incandescent matter.” - -Vögel considers that Zöllner’s hypothesis has been confirmed in its -essential points by the application of spectrum analysis to the stars. -We can recognize from the spectrum different stages in the process -of cooling, and in some of the fainter stars we perceive indeed that -chemical compounds have already formed, and still exist. As to new -stars, again, says Vögel, Zöllner’s theory seems in nowise contradicted -“by the spectral observations made on the two new stars of 1866 and -1876. The bright continuous spectrum, and the bright lines only -slightly exceeding it at first” (a description, however, applying -correctly only to the star of 1876), “could not be well explained if we -only suppose a violent eruption from the interior, which again rendered -the surface wholly or partially luminous; but are easily explained -if we suppose that the quantity of light is considerably augmented -through a simultaneous process of combustion. If this process is of -short duration, then the continuous spectrum, as was the case with the -new star of 1876, will very quickly decrease in intensity down to a -certain limit, while the bright lines in the spectrum, which result -from the incandescent gases that have emanated in enormous quantities -from the interior, will continue for some time.” - -It thus appears that Herr Vögel regarded the observations which had -been made on this remarkable star up to March 10 as indicating that -first there had been an outburst of glowing gaseous matter from the -interior, producing the part of the light which gave the bright -lines indicative of gaseity, and that then there had followed, as a -consequence, the combustion of a portion of the solid and relatively -cool crust, causing the continuous part of the spectrum. We may -compare what had taken place, on this hypothesis, with the outburst of -intensely hot gases from the interior of a volcanic crater, and the -incandescence of the lips of the crater in consequence of the intense -heat of the out-rushing gases. Any one viewing such a crater from a -distance, with a spectroscope, would see the bright lines belonging -to the out-rushing gases superposed upon the continuous spectrum due -to the crater’s burning lips. Vögel further supposes that the burning -parts of the star soon cooled, the majority of the remaining light (or -at any rate the part of the remaining light spectroscopically most -effective) being that which came from the glowing gases which had -emanated in vast quantities from the star’s interior. - -“The observations of the spectrum show, beyond doubt,” he says, “that -the decrease in the light of the star corresponds with the cooling -of its surface. The violet and blue parts decreased more rapidly in -intensity than the other parts; and the absorption-bands which crossed -the spectrum have gradually become darker and darker.” - -The reasoning, however, if not altogether unsatisfactory, is by no -means so conclusive as Herr Vögel appears to think. It is not clear how -the incandescent portion of the surface could possibly cool in any -great degree while enormous quantities of gas more intensely heated (by -the hypothesis) remained around the star. The more rapid decrease in -the violet and blue parts of the spectrum than in the red and orange -is explicable as an effect of absorption, at least as readily as by -the hypothesis that burning solid or liquid matter had cooled. Vögel -himself could only regard the other bands which crossed the spectrum -as absorption-bands. And the absorption of light from the continuous -spectrum in these parts (that is, not where the bright lines belonging -to the gaseous matter lay) could not possibly result from absorption -produced by those gases. If other gases were in question, gases which, -by cooling with the cooling surface, had become capable of thus -absorbing light from special parts of the spectrum, how is it that -before, when these gases were presumably intensely heated, they did not -indicate their presence by bright bands? Bright bands, indeed, were -seen, which eventually faded out of view, but these bright bands did -not occupy the position where, later on, absorption-bands appeared. - -The natural explanation of what had thus far been observed is different -from that advanced by Vögel, though we must not assume that because -it is the natural, it is necessarily the true explanation. It is -this—that the source of that part of the star’s light which gave the -bright-line spectrum, or the spectrum indicative of gaseity, belongs -to the normal condition of the star, and not to gases poured forth, -in consequence of some abnormal state of things, from the sun’s -interior. We should infer naturally, though again I say not _therefore_ -correctly, that if a star spectroscope had been directed upon the -place occupied by the new star before it began to shine with unusual -splendour, the bright-line spectrum would have been observed. Some -exceptional cause would then seem to have aroused the entire surface -of the star to shine with a more intense brightness, the matter thus -(presumably) more intensely heated being such as would give out the -combined continuous and bright-line spectrum, including the bright -lines which, instead of fading out, shone with at least relatively -superior brightness as the star faded from view. The theory that, on -the contrary, the matter giving these more persistent lines was that -whose emission caused the star’s increase of lustre, seems at least not -proven, and I would go so far as to say that it accords ill with the -evidence. - -The question, be it noted, is simply whether we should regard the kind -of light which lasts longest in this star as it fades out of view as -more probably belonging to the star’s abnormal brightness or to its -normal luminosity. It seems to me there can be little doubt that the -persistence of this part of the star’s light points to the latter -rather than to the former view. - -Let it also be noticed that the changes which had been observed thus -far were altogether unlike those which had been observed in the case of -the star in the Northern Crown, and therefore cannot justly be regarded -as pointing to the same explanation. As the star in the Crown faded -from view, the bright lines indicative of glowing hydrogen died out, -and only the ordinary stellar spectrum remained. In the case of the -star in the Swan, the part of the spectrum corresponding to stellar -light faded gradually from view, and bright lines only were left, at -least as conspicuous parts of the star’s spectrum. So that whereas one -orb seemed to have faded into a faint star, the other seemed fading -out into a nebula—not merely passing into such a condition as to -shine with light indicative of gaseity, but actually so changing as -to shine with light of the very tints (or, more strictly, of the very -wave-lengths) observed in all the gaseous nebulæ. - -The strange eventful history of the new star in Cygnus did not end -here, however. We may even say, indeed, that it has not ended yet. But -another chapter can already be written. - -Vögel ceased from observing the star in March, precisely when -observation seemed to promise the most interesting results. At most -other observatories, also, no observations were made for about half -a year. At the Dunecht Observatory[17] pressure of work relating to -Mars interfered with the prosecution of those observations which -had been commenced early in the year. But on September 3, Lord -Lindsay’s 15-inch reflector was directed upon the star. A star was -still shining where the new star’s yellow lustre had been displayed -in November, 1876; but now the star shone with a faint blue colour. -Under spectroscopic examination, however, the light from this seeming -blue star was found not to be starlight, properly speaking, at all. -It formed no rainbow-tinted spectrum, but gave light of only a single -colour. The single line now seen was that which at the time of Vögel’s -latest observation had become the strongest of the bright lines of -the originally complex spectrum of the so-called new star. It is the -brightest of the lines given by the gaseous nebulæ. In fact, if nothing -had been known about this body before the spectroscopic observation -of September 3 was made, the inference from the spectrum given by the -blue star would undoubtedly have been that the object is in reality a -small nebula of the planetary sort, very similar to that one close by -the pole of the ecliptic, which gave Huggins the first evidence of the -gaseity of nebulæ, but very much smaller. I would specially direct the -reader’s attention, in fact, to Huggins’s account of his observation -of that planetary nebula in the Dragon. “On August 19, 1864,” he says, -“I directed the telescope armed with the spectrum apparatus to this -nebula. At first I suspected some derangement of the instrument had -taken place, for no spectrum was seen, but only” a single line of -light. “I then found that the light of this nebula, unlike any other -extra-terrestrial light which had yet been subjected by me to prismatic -analysis, was not composed of light of different refrangibilities, and -therefore could not form a spectrum. A great part of the light from -this nebula is monochromatic, and after passing through the prisms -remains concentrated in a bright line.” A more careful examination -showed that not far from the bright line was a much fainter line; -and beyond this, again, a third exceedingly faint line was seen. The -brightest of the three lines was a line of nitrogen corresponding in -position with the brightest of the lines in the spectrum of our own -air. The faintest corresponded in position with a line of hydrogen. The -other has not yet been associated with a known line of any element. -Besides the faint lines, Dr. Huggins perceived an exceedingly faint -continuous spectrum on both sides of the group of bright lines; he -suspected, however, that this faint spectrum was not continuous, but -crossed by dark spaces. Later observations on other nebulæ induced him -to regard this faint continuous spectrum as due to the solid or liquid -matter of the nucleus, and as quite distinct from the bright lines into -which nearly the whole of the light from the nebula is concentrated. -The fainter parts of the spectrum of the gaseous nebulæ, in fact, -correspond to those parts of the spectrum of the “new star” in Cygnus -which last remained visible, before the light assumed its present -monochromatic colour. - -Now let us consider the significance of the evidence afforded by this -discovery—not perhaps hoping at once to perceive the full meaning of -the discovery, but endeavouring to advance as far as we safely can in -the direction in which it seems to point. - -We have, then, these broad facts: where no star had been known, an -object has for a while shone with stellar lustre, in this sense, that -its light gave a rainbow-tinted spectrum not unlike that which is given -by a certain order of stars; this object has gradually parted with its -new lustre, and in so doing the character of its spectrum has slowly -altered, the continuous portion becoming fainter, and the chief lustre -of the bright-line portion shifting from the hydrogen lines to a line -which, there is every reason to believe, is absolutely identical with -the nebula nitrogen line: and lastly, the object has ceased to give -any perceptible light, other than that belonging to this nitrogen line. - -Now it cannot, I think, be doubted that, accompanying the loss of -lustre in this orb, there has been a corresponding loss of heat. The -theory that all the solid and liquid materials of the orb have been -vaporized by intense heat, and that this vaporization has caused the -loss of the star’s light (as a lime-light might die out with the -consumption of the lime, though the flame remained as hot as ever), -is opposed by many considerations. It seems sufficient to mention -this, that if a mass of solid matter, like a dead sun or planet, were -exposed to an intense heat, first raising it to incandescence, and -eventually altogether vaporizing its materials, although quite possibly -the time of its intensest lustre might precede the completion of the -vaporization, yet certainly so soon as the vaporization was complete, -the spectrum of the newly vaporized mass would show multitudinous -bright lines corresponding to the variety of material existing in the -body. No known fact of spectroscopic analysis lends countenance to the -belief that a solid or liquid mass, vaporized by intense heat, would -shine thenceforth with monochromatic light. - -Again, I think we are definitely compelled to abandon Vögel’s -explanation of the phenomena by Zöllner’s theory. The reasons which -I have urged above are not only strengthened severally by the change -which has taken place in the spectrum of the new star since Vögel -observed it, but an additional argument of overwhelming force has -been introduced. If any one of the suns died out, a crust forming -over its surface and this crust being either absolutely dark or only -shining with very feeble lustre, the sun would still in one respect -resemble all the suns which are spread over the heavens—it would show -no visible disc, however great the telescopic power used in observing -it. If the nearest of all the stars were as large, or even a hundred -times as large, as Sirius, and were observed with a telescope of ten -times greater magnifying power than any yet directed to the heavens, -it would appear only as a point of light. If it lost the best part of -its lustre, it would appear only as a dull point of light. Now the -planetary nebulæ show discs, sometimes of considerable breadth. Sir -J. Herschel, to whom and to Sir W. Herschel we owe the discovery and -observation of nearly all these objects, remarks that “the planetary -nebulæ have, as their name imports, a near, in some instances a -perfect, resemblance to planets, presenting discs round, or slightly -oval, in some quite sharply terminated, in others a little hazy or -softened at the borders....” Among the most remarkable may be specified -one near the Cross, whose light is about equal to that of a star just -visible to the naked eye, “its diameter about twelve seconds, its -disc circular or very slightly elliptic, and with a clear, sharp, -well-defined outline, having exactly the appearance of a planet, with -the exception of its colour, which is a fine and full blue, verging -somewhat upon green.” But the largest of these planetary nebulæ, not -far from the southernmost of the two stars called the Pointers, has -a diameter of 2⅔ minutes of arc, “which, supposing it placed at a -distance from us not greater than that of the nearest known star of our -northern heavens, would imply a linear diameter seven times greater -than that of the orbit of Neptune.” The actual volume of this object, -on this assumption, would exceed our sun’s ten million million times. -No one supposes that this planetary nebula, shining with a light -indicative of gaseity, has a mass exceeding our sun’s in this enormous -degree. It probably has so small a mean density as not greatly to -exceed, or perhaps barely to equal, our sun in mass. Now though the -“new star” in Cygnus presented no measurable disc, and still shines -as a mere blue point in the largest telescope, yet inasmuch as its -spectrum associated it with the planetary and gaseous nebulæ, which -we know to be much larger bodies than the stars, it must be regarded, -in its present condition, as a planetary nebula, though a small one; -and since we cannot for a moment imagine that the monstrous planetary -nebulæ just described are bodies which once were suns, but whose crust -has now become non-luminous, while around the crust masses of gas shine -with a faint luminosity, so are we precluded from believing that this -smaller member of the same family is in that condition. - -It _is_ conceivable (and the possibility must be taken into account -in any attempt to interpret the phenomena of the new star) that when -shining as a star, the new orb, so far as this unusual lustre was -concerned, was of sunlike dimensions. For we cannot tell whether the -surface which gave the strong light was less or greater than, or equal -to, that which is now shining with monochromatic light. Very likely, -if we had been placed where we could have seen the full dimensions of -the planetary nebula as it at present exists, we should have found -only its nuclear part glowing suddenly with increased lustre, which, -after very rapidly attaining its maximum, gradually died out again, -leaving the nebula as it had been before. But that the mass now shining -with monochromatic light is, I will not say enormously large, but -of exceedingly small mean density, so that it is enormously large -compared with the dimensions it would have if its entire substance were -compressed till it had the same mean density as our own sun, must be -regarded as, to all intents and purposes, certain. - -We certainly have not here, then, the case of a sun which has grown -old and dead and dark save at the surface, but within whose interior -fire has still remained, only waiting some disturbing cause to enable -it for a while to rush forth. If we could suppose that in such a case -there _could_ be such changes as the spectroscope has indicated—that -the bright lines of the gaseous outbursting matter would, during the -earlier period of the outburst, show on a bright continuous background, -due to the glowing lips of the opening through which the matter had -rushed, but later would shine alone, becoming also fewer in number, -till at last only one was left,—we should find ourselves confronted -with the stupendous difficulty that that single remaining line is the -bright line of the planetary and other gaseous nebulæ. Any hypothesis -accounting for its existence in the spectrum of the faint blue starlike -object into which the star in Cygnus has faded ought to be competent -to explain its existence in the spectrum of those nebulæ. But _this_ -hypothesis certainly does not so explain its existence in the nebular -spectrum. The nebulæ cannot be suns which have died out save for the -light of gaseous matter surrounding them, for they are millions, or -rather millions of millions, of times too large. If, for instance, a -nebula, like the one above described as lying near the southernmost -Pointer, were a mass of this kind, having the same mean density as -the sun, and lying only at the distance of the nearest of the stars -from us, then not only would it have the utterly monstrous dimensions -stated by Sir J. Herschel, but it would in the most effective way -perturb the whole solar system. With a diameter exceeding seven times -that of the orbit of Neptune, it would have a volume, and therefore a -mass, exceeding our sun’s volume and mass more than eleven millions -of millions of times. But its distance on this assumption would be -only about two hundred thousand times the sun’s, and its attraction -reduced, as compared with his, on this account only forty thousand -millions of times. So that its attraction on the sun and on the earth -would be greater than his attraction on the earth, in the same degree -that eleven millions are greater than forty thousand—or two hundred -and seventy-five times. The sun, despite his enormous distance from -such a mass, would be compelled to fall very quickly into it, unless -he circuited (with all his family) around it in about one-sixteenth of -a year, which most certainly he does not do. Nor would increasing the -distance at which we assume the star to lie have any effect to save -the sun from being thus perturbed, but the reverse. If we double for -instance our estimate of the nebula’s distance, we increase eightfold -our estimate of its mass, while we only diminish its attraction on -our sun fourfold on account of increased distance; so that now its -attraction on our sun would be one-fourth its former attraction -multiplied by eight, or twice our former estimate. We cannot suppose -the nebula to be much nearer than the nearest star. Again, we cannot -suppose that the light of these gaseous nebulæ comes from some bright -orb within them of only starlike apparent dimensions, for in that case -we should constantly recognize such starlike nucleus, which is not the -case. Moreover, the bright-line spectrum from one of these nebulæ comes -from the whole nebula, as is proved by the fact that if the slit of the -spectroscope be opened it becomes possible to see three spectroscopic -images of the nebula itself, not merely the three bright lines. - -So that, if we assume the so-called star in Cygnus to be now like other -objects giving the same monochromatic spectrum—and this seems the only -legitimate assumption—we are compelled to believe that the light now -reaching us comes from a nebulous mass, not from the faintly luminous -envelope of a dead sun. Yet, remembering that when at its brightest -this orb gave a spectrum resembling in general characteristics that of -other stars or suns, and closely resembling even in details that of -stars like Gamma Cassiopeiæ, we are compelled by parity of reasoning -to infer that when the so-called new star was so shining, the greater -part of its light came from a sunlike mass. Thus, then, we are led -to the conclusion that in the case of this body we have a nucleus or -central mass, and that around this central mass there is a quantity of -gaseous matter, resembling in constitution that which forms the bulk -of the other gaseous nebulæ. The denser nucleus ordinarily shines with -so faint a lustre that the continuous spectrum from its light is too -faint to be discerned with the same spectroscopic means by which the -bright lines of the gaseous portion are shown; and the gaseous portion -ordinarily shines with so faint a lustre that its bright lines would -not be discernible on the continuous background of a stellar spectrum. -Through some cause unknown—possibly (as suggested in an article on -the earlier history of this same star in my “Myths and Marvels of -Astronomy”) the rush of a rich and dense flight of meteors upon the -central mass—the nucleus was roused to a degree of heat far surpassing -its ordinary temperature. Thus for a time it glowed as a sun. At the -same time the denser central portions of the nebulous matter were -also aroused to intenser heat, and the bright lines which ordinarily -(and certainly at present) would not stand out bright against the -rainbow-tinted background of a stellar spectrum, showed brightly upon -the continuous spectrum of the new star. Then as the rush of meteors -upon the nucleus and on the surrounding nebulous matter ceased—if -that be the true explanation of the orb’s accession of lustre—or as -the cause of the increase of brightness, whatever that cause may have -been, ceased to act, the central orb slowly returned to its usual -temperature, the nebulous matter also cooling, the continuous spectrum -slowly fading out, the denser parts of the nebulous matter exercising -also a selective absorption (explaining the bands seen in the spectrum -at this stage) which gradually became a continuous absorption—that -is, affected the entire spectrum. Those component gases, also, of the -nebulous portion which had for a while been excited to sufficient heat -to show their bright lines, cooled until their lines disappeared, and -none remained visible except for a while the three usual nebular lines, -and latterly (owing to still further cooling) only the single line -corresponding to the monochromatic light of the fainter gaseous nebulæ. - - - - -_STAR-GROUPING, STAR-DRIFT, AND STAR-MIST._ - -_A Lecture delivered at the Royal Institution on May 6, 1870._ - - -Nearly a century has passed since the greatest astronomer the world has -ever known—the Newton of observational astronomy, as he has justly -been called by Arago—conceived the daring thought that he would gauge -the celestial depths. And because in his day, as indeed in our own, -very little was certainly known respecting the distribution of the -stars, he was forced to found his researches upon a guess. He supposed -that the stars, not only those visible to the naked eye, but all that -are seen in the most powerful telescopes, are suns, distributed with -a certain general uniformity throughout space. It is my purpose to -attempt to prove that—as Sir Wm. Herschel was himself led to suspect -during the progress of his researches—this guess was a mistaken one; -that but a small proportion of the stars can be regarded as real suns; -and that in place of the uniformity of distribution conceived by Sir -Wm. Herschel, the chief characteristic of the sidereal system is -_infinite variety_. - -In order that the arguments on which these views are based may be -clearly apprehended, it will be necessary to recall the main results of -Sir Wm. Herschel’s system of star-grouping. - -Directing one of his 20-feet reflectors to different parts of the -heavens, he counted the stars seen in the field of view. Assuming that -the telescope really reached the limits of the sidereal system, it is -clear that the number of stars seen in any direction affords a means -of estimating the relative extension of the system in that direction, -provided always that the stars are really distributed throughout the -system with a certain approach to uniformity. Where many stars are -seen, there the system has its greatest extension; where few, there the -limits of the system must be nearest to us. - -Sir Wm. Herschel was led by this process of star-grouping to the -conclusion that the sidereal system has the figure of a cloven disc. -The stars visible to the naked eye lie far within the limits of -this disc. Stars outside the relatively narrow limits of the sphere -including all the visible stars, are separately invisible. But where -the system has its greatest extension these orbs produce collectively -the diffused light which forms the Milky Way. - -Sir John Herschel, applying a similar series of researches to the -southern heavens, was led to a very similar conclusion. His view of the -sidereal system differs chiefly in this respect from his father’s, that -he considered the stars within certain limits of distance from the sun -to be spread less richly through space than those whose united lustre -produces the milky light of the galaxy. - -Now it is clear that if the supposition on which these views are based -is just, the three following results are to be looked for. - -In the first place, the stars visible to the naked eye would be -distributed with a certain general uniformity over the celestial -sphere; so that if on the contrary we find certain extensive regions -over which such stars are strewn much more richly than over the rest of -the heavens, we must abandon Sir Wm. Herschel’s fundamental hypothesis -and all the conclusions which have been based upon it. - -In the second place, we ought to find no signs of the aggregation -of lucid stars into streams or clustering groups. If we should find -such associated groups, we must abandon the hypothesis of uniform -distribution and all the conclusions founded on it. - -Thirdly, and most obviously of all, the lucid stars ought not to be -associated in a marked manner with the figure of the Milky Way. To -take an illustrative instance. When we look through a glass window at -a distant landscape we do not find that the specks in the substance -of the glass seem to follow the outline of valleys, hills, trees, or -whatever features the landscape may present. In like manner, regarding -the sphere of the lucid stars as in a sense the window through which we -view the Milky Way, we ought not to find these stars, which are so near -to us, associated with the figure of the Milky Way, whose light comes -from distances so enormously exceeding those which separate us from the -lucid stars. Here again, then, if there should appear signs of such -association, we must abandon the theory that the sidereal system is -constituted as Sir Wm. Herschel supposed. - -It should further be remarked that the three arguments derived from -these relations are independent of each other. They are not as three -links of a chain, any one of which being broken the chain is broken. -They are as three strands of a triple cord. If one strand holds, the -cord holds. It may be shown that all three are to be trusted. - -It is not to be expected, however, that the stars as actually seen -should exhibit these relations, since far the larger number are but -faintly visible; so that the eye would look in vain for the signs of -law among them, even though law may be there. What is necessary is that -maps should be constructed on a uniform and intelligible plan, and that -in these maps the faint stars should be made bright, and the bright -stars brighter. - -The maps exhibited during this discourse [since published as my -“Library Atlas”] have been devised for this purpose amongst others. -There are twelve of them, but they overlap, so that in effect each -covers a tenth part of the heavens. There is first a north-polar map, -then five maps symmetrically placed around it; again, there is a -south-polar map, and five maps symmetrically placed round that map; and -these five so fit in with the first five as to complete the enclosure -of the whole sphere. In effect, every map of the twelve has five maps -symmetrically placed around it and overlapping it. - -Since the whole heavens contain but 5932 stars visible to the naked -eye, each of the maps should contain on the average about 593 stars. -But instead of this being the case, some of the maps contain many more -than their just proportion of stars, while in others the number as -greatly falls short of the average. One recognizes, by combining these -indications, the existence of a roughly circular region, rich in stars, -in the northern heavens, and of another, larger and richer, in the -southern hemisphere. - -To show the influence of these rich regions, it is only necessary to -exhibit the numerical relations presented by the maps. - -The north-polar map, in which the largest part of the northern rich -region falls, contains no less than 693 lucid stars, of which upwards -of 400 fall within the half corresponding to the rich region. Of the -adjacent maps, two contain upwards of 500 stars, while the remaining -three contain about 400 each. Passing to the southern hemisphere, we -find that the south-polar map, which falls wholly within a rich region, -contains no less than 1132 stars! One of the adjacent maps contains 834 -stars, and the four others exhibit numbers ranging from 527 to 595. - -It is wholly impossible not to recognize so unequal a distribution as -exhibiting the existence of special laws of stellar aggregation. - -It is noteworthy, too, that the greater Magellanic cloud falls in -the heart of the southern rich region. Were there not other signs -that this wonderful object is really associated with the sidereal -system, it might be rash to recognize this relation as indicating the -existence of a physical connection between the Nubecula Major and -the southern region rich in stars. Astronomers have indeed so long -regarded the Nubeculæ as belonging neither to the sidereal nor to the -nebular systems, that they are not likely to recognize very readily -the existence of any such connection. Yet how strangely perverse is -the reasoning which has led astronomers so to regard these amazing -objects. Presented fairly, that reasoning amounts simply to this: The -Magellanic clouds contain stars and they contain nebulæ; therefore -they are neither nebular nor stellar. Can perversity of reasoning be -pushed further? Is not the obvious conclusion this, that since nebulæ -and stars are _seen_ to be intermixed in the Nubeculæ, the nebular and -stellar systems form in reality but one complex system? - -As to the existence of star-streams and clustering aggregations, we -have also evidence of a decisive character. There is a well-marked -stream of stars running from near Capella towards Monoceros. Beyond -this lies a long dark rift altogether bare of lucid orbs, beyond which -again lies an extensive range of stars, covering Gemini, Cancer, and -the southern parts of Leo. This vast system of stars resembles a -gigantic sidereal billow flowing towards the Milky Way as towards some -mighty shore-line. Nor is this description altogether fanciful; since -one of the most marked instances of star-drift presently to be adduced -refers to this very region. These associated stars _are_ urging their -way towards the galaxy, and that at a rate which, though seemingly slow -when viewed from beyond so enormous a gap as separates us from this -system, must in reality be estimated by millions of miles in every year. - -Other streams and clustering aggregations there are which need not -here be specially described. But it is worth noticing that all the -well-marked streams recognized by the ancients seem closely associated -with the southern rich region already referred to. This is true of the -stars forming the River Eridanus, the serpent Hydra, and the streams -from the water-can of Aquarius. It is also noteworthy that in each -instance a portion of the stream lies outside the rich region, the rest -within it; while all the streams which lie on the same side of the -galaxy tend towards the two Magellanic clouds. - -Most intimate signs of association between lucid stars and the galaxy -can be recognized—(i.) in the part extending from Cygnus to Aquila; -(ii.) in the part from Perseus to Monoceros; (iii.) over the ship Argo; -and (iv.) near Crux and the feet of Centaurus. - -Before proceeding to the subject of Star-drift, three broad facts may -be stated. They are, I believe, now recognized for the first time, and -seem decisive of the existence of special laws of distribution among -the stars:— - -First, the rich southern region, though covering but a sixth part of -the heavens, contains one-third of all the lucid stars, leaving only -two-thirds for the remaining five-sixths of the heavens. - -Secondly, if the two rich regions and the Milky Way be considered as -one part of the heavens, the rest as another, then the former part is -three times as richly strewn with lucid stars as the second. - -Thirdly, the southern hemisphere contains one thousand more lucid -stars than the northern, a fact which cannot but be regarded as most -striking when it is remembered that the total number of stars visible -to ordinary eyesight in both hemispheres falls short of 6000. - -Two or three years ago, the idea suggested itself to me that if -the proper motions of the stars were examined, they would be found -to convey clear information respecting the existence of variety of -structure, and special laws of distribution within the sidereal system. - -In the first place, the mere amount of a star’s apparent motion must -be regarded as affording a means of estimating the star’s distance. -The nearer a moving object is, the faster it will seem to move, and -_vice versâ_. Of course in individual instances little reliance can be -placed on this indication; but by taking the average proper motions of -a set of stars, a trustworthy measure may be obtained of their average -distance, as compared with the average distance of another set. - -For example, we have in this process the means of settling the question -whether the apparent brightness of a star is indeed a test of relative -nearness. According to accepted theories the sixth-magnitude stars -are ten or twelve times as far off as those of the first magnitude. -Hence their motions should, on the average, be correspondingly small. -Now, to make assurance doubly sure, I divided the stars into two sets, -the first including the stars of the 1st, 2nd, and 3rd, the second -including those of the 4th, 5th, and 6th magnitude. According to -accepted views, the average proper motion for the first set should be -about five times as great as that for the second. I was prepared to -find it about three times as great; that is, not so much greater as -the accepted theories require, but still considerably greater. To my -surprise, I found that the average proper motion of the brighter orders -of stars is barely equal to that of the three lower orders. - -This proves beyond all possibility of question that by far the greater -number of the fainter orders of stars (I refer here throughout to lucid -stars) owe their faintness not to vastness of distance, but to real -relative minuteness. - -To pass over a number of other modes of research, the actual mapping of -the stellar motions, and the discovery of the peculiarity to which I -have given the name of star-drift, remain to be considered. - -In catalogues it is not easy to recognize any instances of community of -motion which may exist among the stars, owing to the method in which -the stars are arranged. What is wanted in this case (as in many others -which yet remain to be dealt with) is the adoption of a plan by which -such relations may be rendered obvious to the eye. The plan I adopted -was to attach to each star in my maps a small arrow, indicating the -amount and direction of that star’s apparent motion in 36,000 years -(the time-interval being purposely lengthened, as otherwise most of the -arrows would have been too small to be recognized). When this was done, -several well-marked instances of community of motion could immediately -be recognized. - -It is necessary to premise, however, that before the experiment was -tried, there were reasons for feeling very doubtful whether it would -succeed. A system of stars might really be drifting athwart the -heavens, and yet the drift might be rendered unrecognizable through -the intermixture of more distant or nearer systems having motions of -another sort and seen accidentally in the same general direction. - -This was found to be the case, indeed, in several instances. Thus the -stars in the constellation Ursa Major, and neighbouring stars in Draco, -exhibit two well-marked directions of drift. The stars β, γ, δ, ε, and -ζ of the Great Bear, besides two companions of the last-named star, -are travelling in one direction, with equal velocity, and clearly form -one system. The remaining stars in the neighbourhood are travelling in -a direction almost exactly the reverse. But even this relation, thus -recognized in a region of diverse motions, is full of interest. Baron -Mädler, the well-known German astronomer, recognizing the community -of motion between ζ Ursæ and its companions, calculated the cyclic -revolution of the system to be certainly not less than 7000 years. But -when the complete system of stars showing this motion is considered, -we get a cyclic period so enormous, that not only the life of man, -but the life of the human race, the existence of our earth, nay, even -the existence of the solar system, must be regarded as a mere day in -comparison with that tremendous cycle. - -Then there are other instances of star-drift where, though two -directions of motion are not intermixed, the drifting nature of the -motion is not at once recognized, because of the various distances at -which the associated stars lie from the eye. - -A case of this kind is to be met with in the stars forming the -constellation Taurus. It was here that Mädler recognized a community -of motion among the stars, but he did not interpret this as I do. He -had formed the idea that the whole of the sidereal system must be in -motion around some central point; and for reasons which need not here -be considered, he was led to believe that in whatever direction the -centre of motion may lie, the stars seen in that general direction -would exhibit a community of motion. Then, that he might not have to -examine the proper motions all over the heavens, he inquired in what -direction (in all probability) the centre of motion may be supposed -to lie. Coming to the conclusion that it must lie towards Taurus, -he examined the proper motions in that constellation, and found a -community of motion which led him to regard Alcyone, the chief star of -the Pleiades, as the centre around which the sidereal system is moving. -Had he examined further he would have found more marked instances of -community of motion in other parts of the heavens, a circumstance which -would have at once compelled him to abandon his hypothesis of a central -sun in the Pleiades, or at least to lay no stress on the evidence -derivable from the community of motion in Taurus. - -Perhaps the most remarkable instance of star-drift is that observed in -the constellations Gemini and Cancer. Here the stars seem to set bodily -towards the neighbouring part of the Milky Way. The general drift -in that direction is too marked, and affects too many stars, to be -regarded as by any possibility referable to accidental coincidence. - -It is worthy of note that if the community of star-drift should be -recognized (or I prefer to say, _when_ it is recognized), astronomers -will have the means of determining the relative distances of the -stars of a drifting system. For differences in the apparent direction -and amount of motion can be due but to differences of distance and -position, and the determination of these differences becomes merely a -question of perspective.[18] - -Before long it is likely that the theory of star-drift will be -subjected to a crucial test, since spectroscopic analysis affords the -means of determining the stellar motions of recess or approach. The -task is a very difficult one, but astronomers have full confidence that -in the able hands of Mr. Huggins it will be successfully accomplished. -I await the result with full confidence that it will confirm my views. -(See pages 92–94 for the result.) - - * * * * * - -Turning to the subject of Star-mist, under which head I include all -orders of nebulæ, I propose to deal with but a small proportion of the -evidence I have collected to prove that none of the nebulæ are external -galaxies. That evidence has indeed become exceedingly voluminous. - -I shall dwell, therefore, on three points only. - -First, as to the distribution of the nebulæ:—They are not spread with -any approach to uniformity over the heavens, but are gathered into -streams and clusters. The one great law which characterizes their -distribution is an avoidance of the Milky Way and its neighbourhood. -This peculiarity has, strangely enough, been regarded by astronomers -as showing that there is no association between the nebulæ and the -sidereal system. They have forgotten that marked contrast is as clear -a sign of association as marked resemblance, and has always been so -regarded by logicians. - -Secondly, there are in the southern heavens two well-marked streams of -nebulæ. Each of these streams is associated with an equally well-marked -stream of stars. Each intermixed stream directs its course towards a -Magellanic Cloud, one towards the Nubecula Minor, the other towards the -Nubecula Major. To these great clusters they flow, like rivers towards -some mighty lake. And within these clusters, which are doubtless -roughly spherical in form, there are found intermixed in wonderful -profusion, stars, star-clusters, and all the orders of nebulæ. Can -these coincidences be regarded as accidental? And if not accidental, -is not the lesson they clearly teach us this, that nebulæ form but -portions of the sidereal system, associating themselves with stars on -terms of equality (if one may so speak), even if single stars be not -more important objects in the scale of creation than these nebulous -masses, which have been so long regarded as equalling, if not outvying, -the sidereal system itself in extent? - -The third point to which I wish to invite attention is the way in which -in many nebulæ stars of considerable relative brightness, and belonging -obviously to the sidereal system, are so associated with nebulous -masses as to leave no doubt whatever that these masses really cling -around them. The association is in many instances far too marked to be -regarded as the effect of accident. - -Among other instances[19] may be cited the nebula round the stars _c_¹ -and _c_² in Orion. In this object two remarkable nebulous nodules -centrally surround two double stars. Admitting the association here to -be real (and no other explanation can reasonably be admitted), we are -led to interesting conclusions respecting the whole of that wonderful -nebulous region which surrounds the sword of Orion. We are led to -believe that the other nebulæ in that region are really associated with -the fixed stars there; that it is not a mere coincidence, for instance, -that the middle star in the belt of Orion is involved in nebula, or -that the lowest star of the sword is similarly circumstanced. It is -a legitimate inference from the evidence that all the nebulæ in this -region belong to one great nebulous group, which extends its branches -to these stars. As a mighty hand, this nebulous region seems to gather -the stars here into close association, showing us, in a way there is no -misinterpreting, that these stars form one system. - -The nebula around the strange variable star, Eta Argûs, is another -remarkable instance of this sort. More than two years ago I ventured -to make two predictions about this object. The first was a tolerably -safe one. I expressed my belief that the nebula would be found to be -gaseous. After Mr. Huggins’s discovery that the great Orion nebula is -gaseous, it was not difficult to see that the Argo nebula must be -so too. At any rate, this has been established by Captain Herschel’s -spectroscopic researches. The other prediction was more venturesome. -Sir John Herschel, whose opinion on such points one would always -prefer to share, had expressed his belief that the nebula lies far out -in space beyond the stars seen in the same field of view. I ventured -to express the opinion that those stars are involved in the nebula. -Lately there came news from Australia that Mr. Le Sueur, with the -great reflector erected at Melbourne, has found that the nebula has -changed largely in shape since Sir John Herschel observed it. Mr. Le -Sueur accordingly expressed his belief that the nebula lies _nearer_ to -us than the fixed stars seen in the same field of view. More lately, -however, he has found that the star Eta Argûs is shining with the -light of burning hydrogen, and he expresses his belief that the star -has consumed the nebulous matter near it. Without agreeing with this -view, I recognize in it a proof that Mr. Le Sueur now considers the -nebula to be really associated with the stars around it. My belief is -that as the star recovers its brilliancy observation will show that the -nebula in its immediate neighbourhood becomes brighter (_not_ fainter -through being consumed as fuel). In fact, I am disposed to regard the -variations of the nebula as systematic, and due to orbital motions -among its various portions around neighbouring stars. - -As indicative of other laws of association bearing on the relations I -have been dealing with, I may mention the circumstance that red stars -and variable stars affect the neighbourhood of the Milky Way or of -well-marked star-streams. The constellation Orion is singularly rich in -objects of this class. It is here that the strange “variable” Betelgeux -lies. At present this star shows no sign of variation, but a few years -ago it exhibited remarkable changes. One is invited to believe that -the star may have been carried by its proper motion into regions where -there is a more uniform distribution of the material whence this orb -recruits its fires. It may be that in the consideration of such causes -of variation affecting our sun in long past ages a more satisfactory -explanation than any yet obtained may be found of the problem -geologists find so perplexing—the former existence of a tropical -climate in places within the temperate zone, or even near the Arctic -regions.[20] - - * * * * * - -It remains that I should exhibit the general results to which I have -been led. It has seemed to many that my views tend largely to diminish -our estimate of the extent of the sidereal system. The exact reverse -is the case. According to accepted views there lie within the range of -our most powerful telescopes millions of millions of suns. According -to mine the primary suns within the range of our telescopes must be -counted by tens of thousands, or by hundreds of thousands at the -outside. What does this diminution of numbers imply but that the space -separating sun from sun is enormously greater than accepted theories -would permit? And this increase implies an enormous increase in the -estimate we are to form of the vital energies of individual suns. For -the vitality of a sun, if one may be permitted the expression, is -measured not merely by the amount of matter over which it exercises -control, but by the extent of space within which that matter is -distributed. Take an orb a thousand times vaster than our sun, and -spread over its surface an amount of matter exceeding a thousandfold -the combined mass of all the planets of the solar system:—So far as -living force is concerned, the result is—_nil_. But distribute that -matter throughout a vast space all round the orb:—That orb becomes -at once fit to be the centre of a host of dependent worlds. Again, -according to accepted theories, when the astronomer has succeeded in -resolving the milky light of a portion of the galaxy into stars, he -has in that direction, at any rate, reached the limits of the sidereal -system. According to my views, what he has really done has been but to -analyze a definite aggregation of stars, a mere corner of that great -system. Yet once more, according to accepted views, thousands and -thousands of galaxies, external to the sidereal system, can be seen -with powerful telescopes. If I am right, the external star-systems lie -far beyond the reach of the most powerful telescope man has yet been -able to construct, insomuch that perchance the nearest of the outlying -galaxies may lie a million times beyond the range even of the mighty -mirror of the great Rosse telescope. - -But this is little. Wonderful as is the extent of the sidereal system -as thus viewed, even more wonderful is its infinite variety. We know -how largely modern discoveries have increased our estimate of the -complexity of the planetary system. Where the ancients recognized -but a few planets, we now see, besides the planets, the families of -satellites; we see the rings of Saturn, in which minute satellites must -be as the sands on the sea-shore for multitude; the wonderful zone -of asteroids; myriads on myriads of comets; millions on millions of -meteor-systems, gathering more and more richly around the sun, until -in his neighbourhood they form the crown of glory which bursts into -view when he is totally eclipsed. But wonderful as is the variety seen -within the planetary system, the variety within the sidereal system is -infinitely more amazing. Besides the single suns, there are groups and -systems and streams of primary suns; there are whole galaxies of minor -orbs; there are clustering stellar aggregations, showing every variety -of richness, of figure, and of distribution; there are all the various -forms of nebulæ, resolvable and irresolvable, circular, elliptical, -and spiral; and lastly, there are irregular masses of luminous gas, -clinging in fantastic convolutions around stars and star-systems. Nor -is it unsafe to assert that other forms and variety of structure will -yet be discovered, or that hundreds more exist which we may never hope -to recognize. - -But lastly, even more wonderful than the infinite variety of the -sidereal system, is its amazing vitality. Instead of millions of inert -masses, we see the whole heavens instinct with energy—astir with busy -life. The great masses of luminous vapour, though occupying countless -millions of cubic miles of space, are moved by unknown forces like -clouds before the summer breeze; star-mist is condensing into clusters; -star-clusters are forming into suns; streams and clusters of minor orbs -are swayed by unknown attractive energies; and primary suns singly or -in systems are pursuing their stately path through space, rejoicing as -giants to run their course, extending on all sides the mighty arm of -their attraction, gathering from ever-new regions of space supplies of -motive energy, to be transformed into the various forms of force—light -and heat and electricity—and distributed in lavish abundance to the -worlds which circle round them. - -Truly may I say, in conclusion, that whether we regard its vast extent, -its infinite variety, or the amazing vitality which pervades its every -portion, the sidereal system is, of all the subjects man can study, -the most imposing and the most stupendous. It is as a book full of -mighty problems—of problems which are as yet almost untouched by man, -of problems which it might seem hopeless for him to attempt to solve. -But those problems are given to him for solution, and he _will_ solve -them, whenever he dares attempt to decipher aright the records of that -wondrous volume. - - - - -_MALLET’S THEORY OF VOLCANOES._ - - -There are few subjects less satisfactorily treated in scientific -treatises than that which Humboldt calls the Reaction of the Earth’s -Interior. We find, not merely in the configuration of the earth’s -crust, but in actual and very remarkable phenomena, evidence of -subterranean forces of great activity; and the problems suggested seem -in no sense impracticable: yet no theory of the earth’s volcanic energy -has yet gained general acceptance. While the astronomer tells us of the -constitution of orbs millions of times further away than our own sun, -the geologist has hitherto been unable to give an account of the forces -which agitate the crust of the orb on which we live. - -The theory put forward respecting volcanic energy, however, by the -eminent seismologist Mallet, promises not merely to take the place -of all others, but to gain a degree of acceptance which has not been -accorded to any theory previously enunciated. It is, in principle, -exceedingly simple, though many of the details (into which I do not -propose to enter) involve questions of considerable difficulty. - -Let us, in the first place, consider briefly the various explanations -which had been already advanced. - -There was first the chemical theory of volcanic energy, the favourite -theory of Sir Humphry Davy. It is possible to produce on a small scale -nearly all the phenomena due to subterranean activity, by simply -bringing together certain substances, and leaving them to undergo -the chemical changes due to their association. As a familiar instance -of explosive action thus occasioned, we need only mention the results -experienced when any one unfamiliar with the methods of treating -lime endeavours over hastily to “slake” or “slack” it with water. -Indeed, one of the strong points of the chemical theory consisted in -the circumstance that volcanoes only occur where water can reach the -subterranean regions—or, as Mallet expresses it, that “without water -there is no volcano.” But the theory is disposed of by the fact, now -generally admitted, that the chemical energies of our earth’s materials -were almost wholly exhausted before the surface was consolidated. - -Another inviting theory is that according to which the earth is -regarded as a mere shell of solid matter surrounding a molten nucleus. -There is every reason to believe that the whole interior of the earth -is in a state of intense heat; and if the increase of heat with depth -(as shown in our mines) is supposed to continue uniformly, we find that -at very moderate depths a degree of heat must prevail sufficient to -liquefy any known solids under ordinary conditions. But the conditions -under which matter exists a few miles only below the surface of the -earth are not ordinary. The pressure enormously exceeds any which our -physicists can obtain experimentally. The ordinary distinction between -solids and liquids cannot exist at that enormous pressure. A mass -of cold steel could be as plastic as any of the glutinous liquids, -while the structural change which a solid undergoes in the process -of liquefying could not take place under such pressure even at an -enormously high temperature. It is now generally admitted that if the -earth really has a molten nucleus, the solid crust must, nevertheless, -be far too thick to be in any way disturbed by changes affecting the -liquid matter beneath. - -Yet another theory has found advocates. The mathematician Hopkins, -whose analysis of the molten-nucleus theory was mainly effective in -showing that theory to be untenable, suggested that there may be -isolated subterranean lakes of fiery matter, and that these may be the -true seat of volcanic energy. But such lakes could not maintain their -heat for ages, if surrounded (as the theory requires) by cooler solid -matter, especially as the theory also requires that water should have -access to them. It will be observed also that none of the theories just -described affords any direct account of those various features of the -earth’s surface—mountain ranges, table-lands, volcanic regions, and so -on—which are undoubtedly due to the action of subterranean forces. The -theory advanced by Mr. Mallet is open to none of these objections. It -seems, indeed, competent to explain all the facts which have hitherto -appeared most perplexing. - -It is recognized by physicists that our earth is gradually parting with -its heat. As it cools it contracts. Now if this process of contraction -took place uniformly, no subterranean action would result. But if the -interior contracts more quickly than the crust, the latter must in some -way or other force its way down to the retreating nucleus. Mr. Mallet -shows that the hotter internal portion must contract faster than the -relatively cool crust; and then he shows that the shrinkage of the -crust is competent to occasion all the known phenomena of volcanic -action. In the distant ages when the earth was still fashioning, the -shrinkage produced the _irregularities of level_ which we recognize in -the elevation of the land and the depression of the ocean-bed. Then -came the period when as the crust shrank it formed _corrugations_, in -other words, when the foldings and elevations of the somewhat thickened -crust gave rise to the mountain-ranges of the earth. Lastly, as the -globe gradually lost its extremely high temperature, the continuance -of the same process of shrinkage led no longer to the formation of -ridges and table-lands, but to local crushing-down and dislocation. -This process is still going on, and Mr. Mallet not only recognizes here -the origin of earthquakes, and of the changes of level now in progress, -but the true cause of volcanic heat. The modern theory of heat as -a form of motion here comes into play. As the solid crust closes in -upon the shrinking nucleus, the work expended in crushing down and -dislocating the parts of the crust is transformed into heat, by which, -at the places where the process goes on with greatest energy, “the -materials of the rock so crushed and of that adjacent to it are heated -even to fusion. The access of water to such points determines volcanic -eruption.” - -Now all this is not mere theorising. Mr. Mallet does not come before -the scientific world with an ingenious speculation, which may or may -not be confirmed by observation and experiment. He has measured and -weighed the forces of which he speaks. He is able to tell precisely -what proportion of the actual energy which must be developed as the -earth contracts is necessary for the production of observed volcanic -phenomena. It is probable that nine-tenths of those who have read -these lines would be disposed to think that the contraction of the -earth must be far too slow to produce effects so stupendous as those -which we recognize in the volcano and the earthquake. But Mr. Mallet -is able to show, by calculations which cannot be disputed, that less -than one-fourth of the heat at present annually lost by the earth is -sufficient to account for the total annual volcanic action, according -to the best data at present in our possession. - -As I have said, I do not propose to follow out Mr. Mallet’s admirable -theory into all its details. I content myself with pointing out how -excellently it accounts for certain peculiarities of the earth’s -surface configuration. Few that have studied carefully drawn charts -of the chief mountain-ranges can have failed to notice that the -arrangement of these ranges does not accord with the idea of upheaval -through the action of internal forces. But it will be at once -recognized that the aspect of the mountain-ranges accords exactly with -what would be expected to result from such a process of contraction -as Mr. Mallet has indicated. The shrivelled skin of an apple affords -no inapt representation of the corrugated surface of our earth, -and according to the new theory, the shrivelling of such a skin is -precisely analogous to the processes at work upon the earth when -mountain-ranges were being formed. Again, there are few students of -geology who have not found a source of perplexity in the foldings and -overlappings of strata in mountainous regions. No forces of upheaval -seem competent to produce this arrangement. But by the new theory this -feature of the earth’s surface is at once explained; indeed, no other -arrangement could be looked for. - -It is worthy of notice that Mr. Mallet’s theory of Volcanic energy -is completely opposed to ordinary ideas respecting earthquakes and -volcanoes. We have been accustomed vaguely to regard these phenomena -as due to the eruptive outbursting power of the earth’s interior; we -shall now have to consider them as due to the subsidence and shrinkage -of the earth’s exterior. Mountains have not been upheaved, but valleys -have sunk down. And in another respect the new theory tends to modify -views which have been generally entertained in recent times. Our -most eminent geologists have taught that the earth’s internal forces -may be as active now as in the epochs when the mountain-ranges were -formed. But Mr. Mallet’s theory tends to show that the volcanic energy -of the earth is a declining force. Its chief action had already been -exerted when mountains began to be formed; what remains now is but -the minutest fraction of the volcanic energy of the mountain-forming -era; and each year, as the earth parts with more and more of its -internal heat, the sources of her subterranean energy are more and more -exhausted. The thought once entertained by astronomers that the earth -might explode like a bomb, her scattered fragments producing a ring of -bodies resembling the zone of asteroids, seems further than ever from -probability; if ever there was any danger of such a catastrophe, the -danger has long since passed away. - - - - -_TOWARDS THE NORTH POLE._ - - -The Arctic Expedition which returned to our shores in the autumn of -1876 may be regarded as having finally decided the question whether -the North Pole of the earth is accessible by the route through Smith’s -Sound—a route which may conveniently and properly be called the -American route. Attacks may hereafter be made on the Polar fastness -from other directions; but it is exceedingly unlikely that this -country, at any rate, will again attempt to reach the Pole along -the line of attack followed by Captain Nares’s expedition. I may be -forgiven, perhaps, for regarding Arctic voyages made by the seamen -of other nations as less likely to be successful than those made by -my own countrymen. It is not mere national prejudice which suggests -this opinion. It is the simple fact that hitherto the most successful -approaches towards both the Northern and the Southern Poles have been -made by British sailors. Nearly a quarter of a century has passed since -Sir E. Parry made the nearest approach to the North Pole recorded up -to that time; and although, in the interval between Parry’s expedition -and Nares’s, no expedition had been sent out from our shores with -the object of advancing towards the Pole, while America, Sweden, -Russia, and Germany sent out several, Parry’s attempt still remained -unsurpassed and unequalled. At length it has been surpassed, but it has -been by his own countrymen. In like manner, no nation has yet succeeded -in approaching the Antarctic Pole so nearly, within many miles, as did -Captain Sir J. C. Ross in 1844. Considering these circumstances, and -remembering the success which rewarded the efforts of Great Britain -in the search for the North-West Passage, it cannot be regarded as -national prejudice to assert that events indicate the seamen of this -country as exceptionally fitted to contend successfully against the -difficulties and the dangers of Arctic exploration. Should England, -then, give up the attempt to reach the North Pole by way of Smith’s -Sound and its northerly prolongation, it may fairly be considered -unlikely that the Pole will ever be reached in that direction. - -It may be well to examine the relative probable chances of success -along other routes which have either not been so thoroughly tried, or -have been tried under less favourable conditions. - -Passing over the unfortunate expedition under Hugh Willoughby in 1553, -the first attempt to penetrate within the Polar domain was made by -Henry Hudson in 1607. The route selected was one which many regard -(and I believe correctly) as the one on which there is the best chance -of success; namely, the route across the sea lying to the west of -Spitzbergen. That Hudson, in the clumsy galleons of Elizabeth’s time, -should have penetrated to within eight degrees and a half of the Pole, -or to a distance only exceeding Nares’s nearest approach by about 130 -miles, proves conclusively, we think, that with modern ships, and -especially with the aid of steam, this route might be followed with -much better prospect of success than that which was adopted for Nares’s -expedition. If the reader will examine a map of the Arctic regions he -will find that the western shores of Spitzbergen and the north-eastern -shores of Greenland, as far as they have been yet explored, are -separated by about 33 degrees of longitude, equivalent on the 80th -parallel of latitude to about 335 miles. Across the whole breadth of -this sea Arctic voyagers have attempted to sail northwards beyond the -80th parallel, but no one has yet succeeded in the attempt except on -the eastern side of that sea. It was here that Hudson—fortunately for -him—directed his attack; and he passed a hundred miles to the north -of the 80th parallel, being impeded and finally stopped by the packed -ice around the north-western shores of Spitzbergen. - -Let us consider the fortunes of other attempts which have been made to -approach the Pole in this direction. - -In 1827 Captain (afterwards Sir Edward) Parry, who had already four -times passed beyond the Arctic Circle—viz., in 1818, 1819, 1821–23, -and 1824–25—made an attempt to reach the North Pole by way of -Spitzbergen. His plan was to follow Hudson’s route until stopped by -ice; then to leave his ship, and cross the ice-field with sledges -drawn by Esquimaux dogs, and, taking boats along with the party, to -cross whatever open water they might find. In this way he succeeded -in reaching latitude 82° 45´ north, the highest ever attained until -Nares’s expedition succeeded in crossing the 83rd parallel. Parry found -that the whole of the ice-field over which his party were laboriously -travelling northwards was being carried bodily southwards, and that at -length the distance they were able to travel in a day was equalled by -the southerly daily drift of the ice-field, so that they made no real -progress. He gave up further contest, and returned to his ship the -_Hecla_. - -It is important to inquire whether the southerly drift which stopped -Parry was due to northerly winds or to a southerly current; and if -to the latter cause, whether this current probably affects the whole -extent of the sea in which Parry’s ice-field was drifting. We know -that his party were exposed, during the greater part of their advance -from Spitzbergen, to northerly winds. Now the real velocity of these -winds must have been greater than their apparent velocity, because the -ice-field was moving southwards. Had this not been the case, or had the -ice-field been suddenly stopped, the wind would have seemed stronger; -precisely as it seems stronger to passengers on board a sailing vessel -when, after being before the wind for a time, she is brought across -the wind. The ice-field was clearly travelling before the wind, but -not nearly so fast as the wind; and therefore there is good reason -for believing that the motion of the ice-field was due to the wind -alone. If we suppose this to have been really the case, then, as there -is no reason for believing that northerly winds prevail uniformly in -the Arctic regions, we must regard Parry’s defeat as due to mischance. -Another explorer might have southerly instead of northerly winds, and -so might be assisted instead of impeded in his advance towards the -Pole. Had this been Parry’s fortune, or even if the winds had proved -neutral, he would have approached nearer to the Pole than Nares. For -Parry reckoned that he had lost more than a hundred miles by the -southerly drift of the ice-field, by which amount at least he would -have advanced further north. But that was not all; for there can be -little doubt that he would have continued his efforts longer but for -the Sisyphæan nature of the struggle. It is true he was nearer home -when he turned back than he would have been but for the drift, and one -of his reasons for turning back was the consideration of the distance -which his men had to travel in returning. But he was chiefly influenced -(so far as the return journey was concerned) by the danger caused by -the movable nature of the ice-field, which might at any time begin to -travel northwards, or eastwards, or westwards. - -If we suppose that not the wind but Arctic currents carried the -ice-field southwards, we must yet admit the probability—nay, almost -the certainty—that such currents are only local, and occupy but a part -of the breadth of the North Atlantic seas in those high latitudes. The -general drift of the North Atlantic surface-water is unquestionably -not towards the south but towards the north; and whatever part we -suppose the Arctic ice to perform in regulating the system of oceanic -circulation—whether, with Carpenter, we consider the descent of -the cooled water as the great moving cause of the entire system of -circulation, or assign to that motion a less important office (which -seems to me the juster opinion)—we must in any case regard the Arctic -seas as a region of surface indraught. The current flowing from those -seas, which caused (on the hypothesis we are for the moment adopting) -the southwardly motion of Parry’s ice-field, must therefore be regarded -as in all probability an exceptional phenomenon of those seas. By -making the advance from a more eastwardly or more westwardly part of -Spitzbergen, a northerly current would probably be met with; or rather, -the motion of the ice-field would indicate the presence of such a -current, for I question very much whether open water would anywhere be -found north of the 83rd parallel. In that case, a party might advance -in one longitude and return in another, selecting for their return -the longitude in which (always according to our present hypothesis -that currents caused the drift) Parry found that a southerly current -underlay his route across the ice. On the whole, however, it appears to -me more probable that winds, not currents, caused the southerly drift -of Parry’s ice-field. - -In 1868, a German expedition, under Captain Koldewey, made the first -visit to the seas west of Spitzbergen in a steamship, the small but -powerful screw steamer _Germania_ (126 tons), advancing northwards -a little beyond the 81st parallel. But this voyage can scarcely be -regarded as an attempt to approach the Pole on that course; for -Koldewey’s instructions were, “to explore the eastern coast of -Greenland northwards; and, if he found success in that direction -impossible, to make for the mysterious Island of Gilles on the east of -Spitzbergen.” - -Scoresby in 1806 had made thus far the most northerly voyage in a ship -on Hudson’s route, but in 1868 a Swedish expedition attained higher -latitudes than had ever or have ever been reached by a ship in that -direction. The steamship _Sofia_, strongly built of Swedish iron, and -originally intended for winter voyages in the Baltic, was selected for -the voyage. Owing to a number of unfortunate delays, it was not until -September, 1868, that the _Sofia_ reached the most northerly part of -her journey, attaining a point nearly fifteen miles further north than -Hudson had reached. To the north broken ice was still found, but it was -so closely packed that not even a boat could pass through. Two months -earlier in the season the voyagers might have waited for a change of -wind and the breaking up of the ice; but in the middle of September -this would have been very dangerous. The temperature was already -sixteen degrees below the freezing-point, and there was every prospect -that in a few weeks, or even days, the seas over which they had reached -their present position would be icebound. They turned back from that -advanced position; but, with courage worthy of the old Vikings, they -made another attack a fortnight later. They were foiled again, as was -to be expected, for by this time the sun was already on the wintry side -of the equator. They had, indeed, a narrow escape from destruction. -“An ice-block with which they came into collision opened a large leak -in the ship’s side, and when, after great exertions, they reached the -land, the water already stood two feet over the cabin floor.”[21] - -On the western side of the North Atlantic Channel—so to term the part -lying between Greenland and Spitzbergen—the nearest approach towards -the Pole was made by the Dutch in 1670, nearly all the more recent -attempts to reach high northern latitudes in this direction having -hitherto ended in failure more or less complete. - -We have already seen that Captain Koldewey was charged to explore the -eastern coast of Greenland in the _Germania_ in 1868. In 1869 the -_Germania_ was again despatched under his command from Bremerhaven, -in company with the _Hansa_, a sailing vessel. Lieutenant Payer and -other Austrian _savants_ accompanied Captain Koldewey. The attack was -again made along the eastern shores of Greenland. As far as the 74th -degree the two vessels kept company; but at this stage it happened -unfortunately that a signal from the _Germania_ was misinterpreted, -and the _Hansa_ left her. Soon after, the _Hansa_ was crushed by masses -of drifting ice, and her crew and passengers took refuge on an immense -ice-floe seven miles in circumference. Here they built a hut, which was -in its turn crushed. Winds and currents carried their icy home about, -and at length broke it up. Fortunately they had saved their boats, and -were able to reach Friedrichsthal, a missionary station in the south of -Greenland, whence they were conveyed to Copenhagen in September, 1870. -Returning to the _Germania_, we find that she had a less unfortunate -experience. She entered the labyrinth of sinuous fjords, separated -by lofty promontories, and girt round by gigantic glaciers, which -characterize the eastern coast of Greenland to the north of Scoresby -Sound. In August the channels by which she had entered were closed, -and the _Germania_ was imprisoned. So soon as the ice would bear -them, Koldewey and his companions made sledging excursions to various -points around their ship. But in November the darkness of the polar -winter settled down upon them, and these excursions ceased. The polar -winter of 1869–70 was “characterized by a series of violent northerly -tempests, one of which continued more than 100 hours, with a velocity -(measured by the anemometer) of no less than sixty miles an hour”—a -velocity often surpassed, indeed, but which must have caused intense -suffering to all who left the shelter of the ship; for it is to be -remembered that the air which thus swept along at the rate of a mile -a minute was the bitter air of the Arctic regions. The thermometer -did not, however, descend lower than 26° below zero, or 58° below the -freezing-point—a cold often surpassed in parts of the United States. I -have myself experienced a cold of more than 30° below zero, at Niagara. -“With proper precautions as regards shelter and clothing,” proceeds -the narrative, “even extreme cold need not cause great suffering to -those who winter in such regions. One of the worst things to be endured -is the physical and moral weariness of being cut off from external -observations during the long night of some ninety days, relieved only -by the strange Northern Lights. The ice accumulates all round with -pressure, and assumes peculiar and fantastic forms, emitting ever and -anon ominous noises. Fortunately, the _Germania_ lay well sheltered -in a harbour opening southwards, and, being protected by a rampart of -hills on the north, was able to resist the shock of the elements. The -sun appearing once more about the beginning of February, the scientific -work of exploration began.... The pioneers of the _Germania_ advanced -as far as the 77th degree of latitude, in longitude 18° 50´ west from -Greenwich. There was no sign of an open sea towards the Pole. _Had it -not been for want of provisions, the party could have prolonged their -sledge journey indefinitely._ The bank of ice, without remarkable -protuberances, extends to about two leagues from the shore, which -from this extreme point seems to trend towards the north-west, where -the view was bounded by lofty mountains.” As the expedition was only -equipped for one winter, it returned to Europe in September, 1870, -without having crossed the 78th parallel of north latitude. - -Captain Koldewey was convinced, by the results of his exploration, -that there is no continuous channel northwards along the eastern coast -of Greenland. It does not seem to me that his expedition proved this -beyond all possibility of question. Still, it seems clear that the -eastern side of the North Atlantic is less suited than the western for -the attempt to reach the North Pole. The prevailing ocean-currents are -southerly on that side, just as they are northerly on the western side. -The cold also is greater, the lines of equal temperature lying almost -exactly in the direction of the channel itself—that is, nearly north -and south—and the cold increasing athwart that direction, towards the -west. The nearer to Greenland the greater is the cold.[22] - -The next route to be considered in order of time would be the American -route; but I prefer to leave this to the last, as the latest results -relate to that route. I take next, therefore, a route which some regard -as the most promising of all—that, namely, which passes between -Spitzbergen and the Scandinavian peninsula. - -It will be remembered that Lieutenant Payer, of the Austrian navy, had -accompanied Captain Koldewey’s first expedition. When driven back from -the attempt to advance along the eastern shores of Greenland, that -commander crossed over to Spitzbergen, and tried to find the Land of -Gilles. He also accompanied Koldewey’s later expedition, and shared his -belief that there is no continuous channel northwards on the western -side of the North Atlantic channel. Believing still, however, with -Dr. Petermann, the geographer, that there is an open Polar sea beyond -the ice-barrier, Payer set out in 1871, in company with Weyprecht, -towards the Land of Gilles. They did not find this mysterious land, -but succeeded in passing 150 miles further north, after rounding the -south-eastern shores of Spitzbergen, than any Arctic voyagers who had -before penetrated into the region lying between Spitzbergen and Novaia -Zemlia. Here they found, beyond the 76th parallel, and between 42° and -60° east longitude, an open sea, and a temperature of between 5° and 7° -above the freezing-point. Unfortunately, they had not enough provisions -with them to be able safely to travel further north, and were thus -compelled to return. The season seems to have been an unusually open -one; and it is much to be regretted that the expedition was not better -supplied with provisions—a defect which appears to be not uncommon -with German expeditions. - -Soon after their return, Payer and Weyprecht began to prepare for a new -expedition; and this time their preparations were thorough, and adapted -for a long stay in Arctic regions. “The chief aim of this expedition,” -says the _Revue des Deux Mondes_, in an interesting account of recent -Polar researches, “was to investigate the unknown regions of the Polar -seas to the north of Siberia, and to try to reach Behring’s Straits -by this route.” It was only if after two winters and three summers -they failed to double the extreme promontory of Asia, that they were -to direct their course towards the Pole. The voyagers, numbering -twenty-four persons, left the Norwegian port of Tromsoë, in the steamer -_Tegethoff_, on July 14, 1872. Count Wilczek followed shortly after -in a yacht, which was to convey coals and provisions to an eastern -point of the Arctic Ocean, for the benefit of the _Tegethoff_. At -a point between Novaia Zemlia and the mouth of the Petschora, the -yacht lost sight of the steamer, and nothing was heard of the latter -for twenty-five months. General anxiety was felt for the fate of the -expedition, and various efforts were made by Austria, England, and -Russia to obtain news of it. In September, 1874, the voyagers suddenly -turned up at another port, and soon after entered Vienna amid great -enthusiasm. Their story was a strange one. - -It appears that when the _Tegethoff_ was lost sight of (August 21, -1872), she had been surrounded by vast masses of ice, which crushed -her hull. For nearly half a year the deadly embrace of the ice -continued; and when at length pressure ceased, the ship remained -fixed in the ice, several miles from open water. During the whole -summer the voyagers tried to release their ship, but in vain. They had -not, however, remained motionless all this time. The yacht had lost -sight of them at a spot between Novaia Zemlia and Malaia Zemlia (in -North Russia) in about 71° north latitude, and they were imprisoned -not far north of this spot. But the ice-field was driven hither -and thither by the winds, until they found themselves, on the last -day of August, 1873, only 6´ or about seven miles south of the 80th -parallel of latitude. Only fourteen miles from them, on the north, -they saw “a mass of mountainous land, with numerous glaciers.” They -could not reach it until the end of October, however, and then they -had to house themselves in preparation for the long winter night. -This land they called Francis Joseph Land. It lies north of Novaia -Zemlia, and on the Polar side of the 80th parallel of latitude. The -winter was stormy and bitterly cold, the thermometer descending on one -occasion to 72° below zero—very nearly as low as during the greatest -cold experienced by Nares’s party. In February, 1874, “the sun having -reappeared, Lieutenant Payer began to prepare sledge excursions to -ascertain the configuration of the land.... In the second excursion -the voyagers entered Austria Sound, which bounds Francis Joseph Island -on the east and north, and found themselves, after emerging from it, -in the midst of a large basin, surrounded by several large islands. -The extreme northern point reached by the expedition was a cape on one -of these islands, which they named Prince Rodolph’s Land, calling the -point Cape Fligely. It lies a little beyond the 81st parallel. They -saw land further north beyond the 83rd degree of latitude, and named -it Petermann’s Land. The archipelago thus discovered is comparable -in extent to that of which Spitzbergen is the chief island.” The -voyagers were compelled now to return, as the firm ice did not extend -further north. They had a long, difficult, and dangerous journey -southwards—sometimes on open water, in small boats, sometimes on -ice, with sledges—impeded part of the time by contrary winds, and -with starvation staring them in the face during the last fortnight of -their journey. Fortunately, they reached Novaia Zemlia before their -provisions quite failed them, and were thence conveyed to Wardhoë by a -Russian trading ship. - -We have now only to consider the attempts which have been made to -approach the North Pole by the American route. For, though Collinson -in 1850 reached high latitudes to the north of Behring’s Straits, while -Wrangel and other Russian voyagers have attempted to travel northwards -across the ice which bounds the northern shores of Siberia, it can -hardly be said that either route has been followed with the definite -purpose of reaching the North Pole. I shall presently, however, have -occasion to consider the probable value of the Behring’s Straits route, -which about twelve years ago was advocated by the Frenchman Lambert. - -Dr. Kane’s expedition in 1853–55 was one of those sent out in search -of Sir John Franklin. It was fitted out at the expense of the United -States Government, and the route selected was that along Smith’s Sound, -the northerly prolongation of Baffin’s Bay. Kane wintered in 1853 and -1854 in Van Reusselaer’s Inlet, on the western coast of Greenland, in -latitude 78° 43´ north. Leaving his ship, the _Advance_, he made a -boat-journey to Upernavik, 6° further south. He next traced Kennedy -Channel, the northerly prolongation of Smith’s Sound, reaching latitude -81° 22´ north. He named heights visible yet further to the north, -Parry Mountains; and at the time—that is, twenty-two years ago—the -land so named was the highest northerly land yet seen. Hayes, who had -accompanied Kane in this voyage, succeeded in reaching a still higher -latitude in sledges drawn by Esquimaux dogs. Both Kane and Hayes agreed -in announcing that where the shores of Greenland trend off eastwards -from Kennedy Channel, there is an open sea, “rolling,” as Captain Maury -magniloquently says, “with the swell of a boundless ocean.” It was in -particular noticed that the tides ebbed and flowed in this sea. On this -circumstance Captain Maury based his conclusion that there is an open -sea to the north of Greenland. After showing that the tidal wave could -not well have travelled along the narrow and icebound straits between -Baffin’s Bay and the region reached by Kane and Hayes, Maury says: -“Those tides must have been born in that cold sea, having their cradle -about the North Pole.” The context shows, however, that he really -intended to signify that the waves were formed in seas around the North -Pole, and thence reached the place where they were seen; so that, as -birth usually precedes cradling, Maury would more correctly have said -that these tides are cradled in that cold sea, having their birth about -the North Pole. - -The observations of Kane and Hayes afford no reason, however, for -supposing that there is open water around the North Pole. They have -been rendered somewhat doubtful, be it remarked in passing, by the -results of Captain Nares’s expedition; and it has been proved beyond -all question that there is not an open sea directly communicating with -the place where Kane and Hayes observed tidal changes. But, apart -from direct evidence of this kind, two serious errors affect Maury’s -reasoning, as I pointed out eleven years since. In the first place, -a tidal wave would be propagated quite freely along an ice-covered -sea, no matter how thick the ice might be, so long as the sea was not -absolutely icebound. Even if the latter condition could exist for a -time, the tidal wave would burst the icy fetters that bound the sea, -unless the sea were frozen to the very bottom; which, of course, can -never happen with any sea properly so called. It must be remembered -that, even in the coldest winter of the coldest Polar regions, ice -of only a moderate thickness can form in open sea in a single day; -but the tidal wave does not allow ice to form for a single hour in -such sort as to bind the great ice-fields and the shore-ice into one -mighty mass. At low tide, for a very short time, ice may form in the -spaces between the shore-ice and the floating ice, and again between -the various masses of floating ice, small or large (up to many square -miles in extent); but as the tidal wave returns it breaks through these -bonds as easily as the Jewish Hercules burst the withes with which the -Philistines had bound his mighty limbs. It is probable that if solid -ice as thick as the thickest which Nares’s party found floating in the -Palæocrystic Sea—ice 200 feet thick—reached from shore to shore of -the North Atlantic channel, the tidal wave would burst the barrier as -easily as a rivulet rising but a few inches bursts the thin coating -which has formed over it on the first cold night of autumn. But no such -massive barriers have to be broken through, for the tidal wave never -gives the ice an hour’s rest Maury reasons that “the tidal wave from -the Atlantic can no more pass under the icy barrier to be propagated -in the seas beyond, than the vibrations of a musical string can pass -with its notes a fret on which the musician has placed his finger.” But -the circumstances are totally different. The ice shares the motion of -the tidal wave, which has not to pass under the ice, but to lift it. -This, of course, it does quite as readily as though there were no ice, -but only the same weight of water. The mere weight of the ice counts -simply for nothing. The tidal wave would rise as easily in the British -Channel if a million Great Easterns were floating there as if there was -not even a cock-boat; and the weight of ice, no matter how thick or -extensive, would be similarly ineffective to restrain the great wave -which the sun and moon send coursing twice a day athwart our oceans. -Maury’s other mistake was even more important so far as this question -of an open sea is concerned. “No one,” as I wrote in 1867, “who is -familiar with the astronomical doctrine of the tides, can believe for -a moment that tides could be generated in a land-locked ocean, so -limited in extent as the North Polar sea (assuming its existence) must -necessarily be.” To raise a tidal wave the sun and moon require not -merely an ocean of wide extent to act upon, but an ocean so placed that -there is a great diversity in their pull on various parts of it; for it -is the difference between the pull exerted on various parts, and not -the pull itself, which creates the tidal wave. Now the Polar sea has -not the required extent, and is not in the proper position, for this -diversity of pull to exist in sufficient degree to produce a tidal wave -which could be recognized. It is certain, in fact, that, whether there -is open water or not near the Pole, the tides observed by Kane and -Hayes must have come from the Atlantic, and most probably by the North -Atlantic channel. - -Captain Hall’s expedition in the _Polaris_ (really under the command -of Buddington), in 1871–72, will be probably in the recollection of -most of my readers. Leaving Newfoundland on June 29, 1871, it sailed up -Smith’s Sound, and by the end of August had reached the 80th parallel. -Thence it proceeded up Kennedy Channel, and penetrated into Robeson -Channel, the northerly prolongation of Kennedy Channel, and only 13 -miles wide. Captain Hall followed this passage as far as 82° 16´ north -latitude, reaching his extreme northerly point on September 3. From it -he saw “a vast expanse of open sea, which he called Lincoln Sea, and -beyond that another ocean or gulf; while on the west there appeared, -as far as the eye could reach, the contours of coast. This region he -called Grant Land.” So far as appears, there was no reason at that time -why the expedition should not have gone still further north, the season -apparently having been exceptionally open. But the naval commander of -the expedition, Captain Buddington, does not seem to have had his heart -in the work, and, to the disappointment of Hall, the _Polaris_ returned -to winter in Robeson Channel, a little beyond the 81st degree. In the -same month, September, 1871, Captain Hall died, under circumstances -which suggested to many of the crew and officers the suspicion that -he had been poisoned.[23] In the spring of 1870 the _Polaris_ resumed -her course homewards. They were greatly impeded by the ice. A party -which got separated from those on board were unfortunately unable to -regain the ship, and remained on an ice-field for 240 days, suffering -fearfully. The ice-field, like that on which the crew of the _Hansa_ -had to take up their abode, drifted southwards, and was gradually -diminishing, when fortunately a passing steamer observed the prisoners -(April 30, 1872) and rescued them. The _Polaris_ herself was so injured -by the ice that her crew had to leave her, wintering on Lyttelton -Island. They left this spot in the early summer of 1872, in two boats, -and were eventually picked up by a Scotch whaler. - -Captain Nares’s expedition followed Hall’s route. I do not propose to -enter here into any of the details of the voyage, with which my readers -are no doubt familiar. The general history of the expedition must be -sketched, however, in order to bring it duly into its place here. The -_Alert_ and _Discovery_ sailed under Captains Nares and Stephenson, in -May, 1875. Their struggle with the ice did not fairly commence until -they were nearing the 79th parallel, where Baffin’s Bay merges into -Smith’s Sound. Thence, through Smith’s Sound, Kennedy Channel, and -Robeson Channel, they had a constant and sometimes almost desperate -struggle with the ice, until they had reached the north end of Robeson -Channel. Here the _Discovery_ took up her winter quarters, in north -latitude 81° 44´, a few miles north of Captain Hall’s wintering-place, -but on the opposite (or westerly) side of Robeson Channel. The _Alert_ -still struggled northwards, rounding the north-east point of Grant -Land, and there finding, not, as was expected, a continuous coast-line -on the west, but a vast icebound sea. No harbour could be found, and -the ship was secured on the inside of a barrier of grounded ice, in -latitude 82° 31´, in the most northerly wintering-place ever yet -occupied by man. The ice met with on this sea is described as “of most -unusual age and thickness, resembling in a marked degree, both in -appearance and formation, low floating icebergs rather than ordinary -salt-water ice. Whereas ordinary ice is from 2 feet to 10 feet in -thickness, that in this Polar sea has gradually increased in age and -thickness until it measures from 80 feet to 120 feet, floating with -its surface at the lower part 15 feet above the water-line. In some -places the ice reaches a thickness of from 150 to 200 feet, and the -general impression among the officers of the expedition seems to have -been that the ice of this Palæocrystic Sea is the accumulation of many -years, if not of centuries; “that the sea is never free of it and never -open; and that progress to the Pole through it or over it is impossible -with our present resources.” - -The winter which followed was the bitterest ever known by man. For -142 days the sun was not seen; the mercury was frozen during nearly -nine weeks. On one occasion the thermometer showed 104° below the -freezing-point, and during one terrible fortnight the mean temperature -was 91° below freezing! - -As soon as the sun reappeared sledge-exploration began, each ship being -left with only half-a-dozen men and officers on board. Expeditions were -sent east and west, one to explore the northern coast of Greenland, the -other to explore the coast of Grant Land. Captain Stephenson crossed -over from the _Discovery’s_ wintering-place to Polaris Bay, and there -placed over Hall’s grave a tablet, prepared in England, bearing the -following inscription: “Sacred to the memory of Captain C. F. Hall, of -U.S. _Polaris_, who sacrificed his life in the advancement of science, -on November 8, 1871. This tablet has been erected by the British Polar -Expedition of 1875, who, following in his footsteps, have profited by -his experience”—a graceful acknowledgment (which might, however, have -been better expressed). The party which travelled westwards traced -the shores of Grant Land as far as west longitude 86° 30´, the most -northerly cape being in latitude 83° 7´, and longitude 70° 30´ west. -This cape they named Cape Columbia. - -The coast of Greenland was explored as far east as longitude 50° 40´ -(west), land being seen as far as 82° 54´ north, longitude 48° 33´ -west. Lastly, a party under Commander Markham and Lieutenant Parr -pushed northwards. They were absent ten weeks, but had not travelled -so far north in the time as was expected, having encountered great -difficulties. On May 12, 1876, they reached their most northerly point, -planting the British flag in latitude 83° 20´ 26´´ north. “Owing to -the extraordinary nature of the pressed-up ice, a roadway had to be -formed by pickaxes for nearly half the distance travelled, before any -advance could be safely made, even with light loads; this rendered it -always necessary to drag the sledge-loads forward by instalments, and -therefore to journey over the same road several times. The advance was -consequently very slow, and only averaged about a mile and a quarter -daily—much the same rate as was attained by Sir Edward Parry during -the summer of 1827. The greatest journey made in any one day amounted -only to two miles and three quarters. Although the distance made good -was only 73 miles from the ship, 276 miles were travelled over to -accomplish it.” It is justly remarked, in the narrative from which I -have made this extract, that no body of men could have surpassed in -praiseworthy perseverance this gallant party, whose arduous struggle -over the roughest and most monotonous road imaginable, may fairly be -regarded as surpassing all former exploits of the kind. (The narrator -says that it has “eclipsed” all former ones, which can scarcely be -intended to be taken _au pied de la lettre_.) The expedition reached -the highest latitude ever yet attained under any conditions, carried -a ship to higher latitudes than any ship had before reached, and -wintered in higher latitudes than had ever before been dwelt in during -the darkness of a Polar winter. They explored the most northerly -coast-line yet traversed, and this both on the east and west of their -route northwards. They have ascertained the limits of human habitation -upon this earth, and have even passed beyond the regions which animals -occupy, though nearly to the most northerly limit of the voyage they -found signs of the occasional visits of warm-blooded animals. Last, but -not least, they have demonstrated, as it appears to me (though possibly -Americans will adopt a different opinion), that by whatever route the -Pole is to be reached, it is not by that which I have here called -the American route, at least with the present means of transit over -icebound seas. The country may well be satisfied with such results -(apart altogether from the scientific observations, which are the -best fruits of the expedition), even though the Pole has not yet been -reached. - -Must we conclude, however, that the North Pole is really inaccessible? -It appears to me that the annals of Arctic research justify no such -conclusion. The attempt which has just been made, although supposed at -the outset to have been directed along the most promising of all the -routes heretofore tried, turned out to be one of the most difficult -and dangerous. Had there been land extending northwards (as Sherard -Osborn and others opined), on the western side of the sea into which -Robeson Channel opens, a successful advance might have been made along -its shore by sledging. M’Clintock, in 1853, travelled 1220 miles in 105 -days; Richards 1012 miles in 102 days; Mecham 1203 miles; Richards and -Osborn 1093 miles; Hamilton 1150 miles with a dog-sledge and one man. -In 1854 Mecham travelled 1157 miles in only 70 days; Young travelled -1150 miles and M’Clintock 1330 miles. But these journeys were made -either over land or over unmoving ice close to a shore-line. Over an -icebound sea journeys of the kind are quite impracticable. But the -conditions, while not more favourable in respect of the existence of -land, were in other respects altogether less favourable along the -American route than along any of the others I have considered in this -brief sketch of the attempts hitherto made to reach the Pole. - -The recent expedition wintered as near as possible to the region of -maximum winter cold in the western hemisphere, and pushed their journey -northwards athwart the region of maximum summer cold. Along the course -pursued by Parry’s route the cold is far less intense, in corresponding -latitudes, than along the American route; and cold is the real enemy -which bars the way towards the Pole. All the difficulties and dangers -of the journey either have their origin (as directly as the ice itself) -in the bitter Arctic cold, or are rendered effective and intensified -by the cold. The course to be pursued, therefore, is that indicated -by the temperature. Where the July isotherms, or lines of equal summer -heat, run northwards, a weak place is indicated in the Arctic barrier; -where they trend southwards, that barrier is strongest. Now there are -two longitudes in which the July Arctic isotherms run far northward -of their average latitude. One passes through the Parry Islands, and -indicates the sea north-east of Behring’s Straits as a suitable region -for attack; the other passes through Spitzbergen, and indicates the -course along which Sir E. Parry’s attack was made. The latter is -slightly the more promising line of the two, so far as temperature is -concerned, the isotherm of 36° Fahrenheit (in July) running here as -far north as the 77th parallel, whereas its highest northerly range in -the longitude of the Parry Islands is but about 76°. The difference, -however, is neither great nor altogether certain; and the fact that -Parry found the ice drifting southwards, suggests the possibility that -that _may_ be the usual course of oceanic currents in that region. -North of the Parry Islands the drift may be northwardly, like that -which Payer and Weyprecht experienced to the north of Novaia Zemlia. - -There is one great attraction for men of science in the route by the -Parry Islands. The magnetic pole has almost certainly travelled into -that region. Sir J. Ross found it, indeed, to be near Boothia Gulf, -far to the east of the Parry Islands, in 1837. But the variations of -the needle all over the world since then, indicate unmistakably that -the magnetic poles have been travelling round towards the west, and at -such a rate that the northern magnetic pole has probably nearly reached -by this time the longitude of Behring’s Straits. The determination of -the exact present position of the Pole would be a much more important -achievement, so far as science is concerned, than a voyage to the pole -of rotation. - -There is one point which suggests itself very forcibly in reading the -account of the sledging expedition from the _Alert_ towards the north. -In his official report, Captain Nares says that “half of each day was -spent in dragging the sledges in that painful fashion—face toward the -boat—in which the sailors drag a boat from the sea on to the sand;” -and again he speaks of the “toilsome dragging of the sledges over -ice-ridges which resembled a stormy sea suddenly frozen.” In doing -this “276 miles were toiled over in travelling only 73 miles.” Is it -altogether clear that the sledges were worth the trouble? One usually -regards a sledge as intended to carry travellers and their provisions, -etc., over ice and snow, and as useful when so employed; but when the -travellers have to take along the sledge, going four times as far and -working ten times as hard as if they were without it, the question -suggests itself whether all necessary shelter, provisions, and utensils -might not have been much more readily conveyed by using a much smaller -and lighter sledge, and by distributing a large part of the luggage -among the members of the expedition. The parts of a small hut could, -with a little ingenuity, be so constructed as to admit of being used as -levers, crowbars, carrying-poles, and so forth, and a large portion of -the luggage absolutely necessary for the expedition could be carried by -their help; while a small, light sledge for the rest could be helped -along and occasionally lifted bodily over obstructions by levers and -beams forming part of the very material which by the usual arrangement -forms part of the load. I am not suggesting, be it noticed, that by any -devices of this sort a journey over the rough ice of Arctic regions -could be made easy. But it does seem to me that if a party could go -back and forth over 276 miles, pickaxing a way for a sledge, and -eventually dragging it along over the path thus pioneered for it, and -making only an average of 1¼ mile of real progress per day, or 73 miles -in all, the same men could with less labour (though still, doubtless, -with great toil and trouble) make six or seven miles a day by reducing -their _impedimenta_ to what could be carried directly along with them. -Whether use might not be made of the lifting power of buoyant gas, is -a question which only experienced aëronauts and Arctic voyagers could -answer. I believe that the employment of imprisoned balloon-power for -many purposes, especially in time of war, has received as yet much less -attention than it deserves. Of course I am aware that in Arctic regions -many difficulties would present themselves; and the idea of ordinary -ballooning over the Arctic ice-fields may be regarded as altogether -wild in the present condition of the science of aëronautics. But the -use of balloon-power as an auxiliary, however impracticable at present, -is by no means to be despaired of as science advances. - -After all, however, the advance upon the Pole itself, however -interesting to the general public, is far less important to science -than other objects which Arctic travellers have had in view. The -inquiry into the phenomena of terrestrial magnetism within the Arctic -regions; the investigation of oceanic movements there; of the laws -according to which low temperatures are related to latitude and -geographical conditions; the study of aerial phenomena; of the limits -of plant life and animal life; the examination of the mysterious -phenomena of the Aurora Borealis—these and many other interesting -subjects of investigation have been as yet but incompletely dealt with. -In the Polar regions, as Maury well remarked, “the icebergs are framed -and glaciers launched; there the tides have their cradle, the whales -their nursery; there the winds complete their circuit, and the currents -of the sea their round, in the wonderful system of oceanic circulation; -there the Aurora is lighted up, and the trembling needle brought to -rest; and there, too, in the mazes of that mystic circle, terrestrial -forces of occult power and of vast influence upon the well-being of man -are continually at work. It is a circle of mysteries; and the desire to -enter it, to explore its untrodden wastes and secret chambers, and to -study its physical aspects, has grown into a longing. Noble daring has -made Arctic ice and snow-clad seas classic ground.” - - - - -_A MIGHTY SEA-WAVE._ - - -On May 10th, 1876, a tremendous wave swept the Pacific Ocean from Peru -northwards, westwards, and southwards, travelling at a rate many times -greater than that of the swiftest express train. For reasons best known -to themselves, writers in the newspapers have by almost common consent -called this phenomenon a tidal-wave. But the tides had nothing to do -with it. Unquestionably the wave resulted from the upheaval of the bed -of the ocean in some part of that angle of the Pacific Ocean which is -bounded by the shores of Peru and Chili. This region has long been -celebrated for tremendous submarine and subterranean upheavals. The -opinions of geologists and geographers have been divided as to the real -origin of the disturbances by which at one time the land, at another -time the sea, and at yet other times (oftener, in fact, than either -of the others) both land and sea have been shaken as by some mighty -imprisoned giant, struggling, like Prometheus, to cast from his limbs -the mountain masses which hold them down. Some consider that the seat -of the Vulcanian forces lies deep below that part of the chain of the -Andes which lies at the apex of the angle just mentioned, and that the -direction of their action varies according to the varying conditions -under which the imprisoned gases find vent. Others consider that there -are two if not several seats of subterranean activity. Yet others -suppose that the real seat of disturbance lies beneath the ocean -itself, a view which seems to find support in several phenomena of -recent Peruvian earthquakes. - -Although we have not full information concerning the great wave which -in May, 1876, swept across the Pacific, and northwards and southwards -along the shores of the two Americas, it may be interesting to consider -some of the more striking features of this great disturbance of the -so-called peaceful ocean, and to compare them with those which have -characterized former disturbances of a similar kind. We may thus, -perhaps, find some evidence by which an opinion may be formed as to the -real seat of subterranean activity in this region. - -At the outset it may be necessary to explain why I have asserted -somewhat confidently that the tides have nothing whatever to do with -this great oceanic wave. It is of course well known to every reader -that the highest or spring tides occur always two or three days after -new moon and after full moon, the lowest (or rather the tides having -least range above and below the mean level) occurring two or three days -after the first and third quarters of the lunar month. The sun and moon -combine, indeed, to sway the ocean most strongly at full and new, while -they pull contrariwise at the first and third quarters; but the full -effect of their combined effort is only felt a few days later than when -it is made, while the full effect of their opposition to each other, -in diminishing the range of the oceanic oscillation, is also only felt -after two or three days. Thus in May, 1876, the tidal wave had its -greatest range on or about May 16, new moon occurring at half-past five -on the morning of May 13; and the tidal wave had its least range on or -about May 8, the moon passing her third quarter a little after eleven -on the morning of May 4. Accordingly the disturbance which affected the -waters of the Pacific so mightily on May 10, occurred two days after -the lowest or neap tides, and five days before the highest or spring -tides. Manifestly that was not a time when a tidal wave of exceptional -height could be expected, or, indeed, could possibly occur. Such a -wave as actually disturbed the Pacific on that day could not in any -case have been produced by tidal action, even though the winds had -assisted to their utmost, and all the circumstances which help to make -high tides had combined—as the greatest proximity of moon to earth, -the conjunction of moon and sun near the celestial equator, and (of -course) the exact coincidence of the time of the tidal disturbance -with that when the combined pull of the sun and moon is strongest. As, -instead, the sun was nearly eighteen degrees from the equator, the moon -more than nine, and as the moon was a full week’s motion from the part -of her path where she is nearest to the earth, while, as we have seen, -only two days had passed from the time of absolutely lowest tides, it -will be seen how utterly unable the tidal-wave must have been on the -day of the great disturbance to produce the effects presently to be -described. - -It may seem strange, in dealing with the case of a wave which -apparently had its origin in or near Peru on May 9, to consider the -behaviour of a volcano, distant 5000 miles from this region, a week -before the disturbance took place. But although the coincidence may -possibly have been accidental, yet in endeavouring to ascertain -the true seat of disturbance we must overlook no evidence, however -seemingly remote, which may throw light on that point; and as the -sea-wave generated by the disturbance reached very quickly the distant -region referred to, it is by no means unlikely that the subterranean -excitement which the disturbance relieved may have manifested its -effects beforehand at the same remote volcanic region. Be this as -it may, it is certain that on May 1 the great crater of Kilauea, in -the island of Hawaii, became active, and on the 4th severe shocks of -earthquake were felt at the Volcano House. At three in the afternoon a -jet of lava was thrown up to a height of about 100 feet, and afterwards -some fifty jets came into action. Subsequently jets of steam issued -along the line formed by a fissure four miles in length down the -mountain-side. The disturbance lessened considerably on the 5th, and an -observing party examined the crater. They found that a rounded hill, -700 feet in height, and 1400 feet in diameter, had been thrown up on -the plain which forms the floor of the crater. Fire and scoria spouted -up in various places. - -Before rejecting utterly the belief that the activity thus exhibited in -the Hawaii volcano had its origin in the same subterrene or submarine -region as the Peruvian earthquake, we should remember that other -regions scarcely less remote have been regarded as forming part of the -same Vulcanian district. The violent earthquakes which occurred at -New Madrid, in Missouri, in 1812, took place at the same time as the -earthquake of Caraccas, the West Indian volcanoes being simultaneously -active; and earthquakes had been felt in South Carolina for several -months before the destruction of Caraccas and La Guayra. Now we have -abundant evidence to show that the West Indian volcanoes are connected -with the Peruvian and Chilian regions of Vulcanian energy, and the -Chilian region is about as far from New Madrid as Arica in Peru from -the Sandwich Isles. - -It was not, however, until about half-past eight on the evening of May -9 that the Peruvian earthquake began. A severe shock, lasting from -four to five minutes, was felt along the entire southern coast, even -reaching Antofagasta. The shock was so severe that it was impossible, -in many places, to stand upright. It was succeeded by several others of -less intensity. - -While the land was thus disturbed, the sea was observed to be gradually -receding, a movement which former experiences have taught the Peruvians -to regard with even more terror than the disturbance of the earth -itself. The waters which had thus withdrawn, as if concentrating their -energies to leap more fiercely on their prey, presently returned in -a mighty wave, which swept past Callao, travelling southwards with -fearful velocity, while in its train followed wave after wave, until -no less than eight had taken their part in the work of destruction. -At Mollendo the railway was torn up by the sea for a distance of 300 -feet. A violent hurricane which set in afterwards from the south -prevented all vessels from approaching, and unroofed most of the houses -in the town. At Arica the people were busily engaged in preparing -temporary fortifications to repel a threatened assault of the rebel ram -_Huiscar_, at the moment when the roar of the earthquake was heard. -The shocks here were very numerous, and caused immense damage in the -town, the people flying to the Morro for safety. The sea was suddenly -perceived to recede from the beach, and a wave from ten feet to fifteen -feet in height rolled in upon the shore, carrying before it all that it -met. Eight times was this assault of the ocean repeated. The earthquake -had levelled to the ground a portion of the custom-house, the railway -station, the submarine cable office, the hotel, the British Consulate, -the steamship agency, and many private dwellings. Owing to the early -hour of the evening, and the excitement attendant on the proposed -attack of the _Huiscar_, every one was out and stirring; but the only -loss of life which was reported was that of three little children who -were overtaken by the water. The progress of the wave was only stopped -at the foot of the hill on which the church stands, which point is -further inland than that reached in August, 1868. Four miles of the -embankment of the railway were swept away like sand before the wind. -Locomotives, cars, and rails, were hurled about by the sea like so many -playthings, and left in a tumbled mass of rubbish. - -The account proceeds to say that the United States steamer _Waters_, -stranded by the bore of 1868, was lifted up bodily by the wave at -Arica, and floated two miles north of her former position. The -reference is no doubt to the double-ender _Watertree_, not stranded by -a bore (a term utterly inapplicable to any kind of sea-wave at Arica, -where there is no large river), but carried in by the great wave which -followed the earthquake of August 13. The description of the wave at -Arica on that occasion should be compared with that of the wave of -May, 1876. About twenty minutes after the first earth shock, the sea -was seen to retire, as if about to leave the shores wholly dry; but -presently its waters returned with tremendous force. A mighty wave, -whose length seemed immeasurable, was seen advancing like a dark wall -upon the unfortunate town, a large part of which was overwhelmed by -it. Two ships, the Peruvian corvette _America_, and the American -double-ender _Watertree_, were carried nearly half a mile to the north -of Arica, beyond the railroad which runs to Tacna, and there left -stranded high and dry. As the English vice-consul at Arica estimated -the height of this enormous wave at fully fifty feet, it would not seem -that the account of the wave of May, 1876, has been exaggerated, for a -much less height is, as we have seen, attributed to it, though, as it -carried the _Watertree_ still further inland, it must have been higher. -The small loss of life can be easily understood when we consider that -the earthquake was not followed instantly by the sea-wave. Warned by -the experience of the earthquake of 1868, which most of them must have -remembered, the inhabitants sought safety on the higher grounds until -the great wave and its successors had flowed in. We read that the -damage done was greater than that caused by the previous calamity, the -new buildings erected since 1868 being of a more costly and substantial -class. Merchandise from the custom-house and stores was carried by the -water to a point on the beach five miles distant. - -At Iquique, in 1868, the great wave was estimated at fifty feet in -height. We are told that it was black with the mud and slime of the sea -bottom. “Those who witnessed its progress from the upper balconies of -their houses, and presently saw its black mass rushing close beneath -their feet, looked on their safety as a miracle. Many buildings were, -indeed, washed away, and in the low-lying parts of the town there was a -terrible loss of life.” In May, 1876, the greatest mischief at Iquique -would seem to have been caused by the earthquake, not by the sea-wave, -though this also was destructive in its own way. “Iquique,” we are -told, “is in ruins. The movement was experienced there at the same time -and with the same force [as at Arica]. Its duration was exactly four -minutes and a third. It proceeded from the south-east, exactly from the -direction of Ilaga.” The houses built of wood and cane tumbled down at -the first attacks, lamps were broken, and the burning oil spread over -and set fire to the ruins. Three companies of firemen, German, Italian, -and Peruvian, were instantly at their posts, although it was difficult -to maintain an upright position, shock following shock with dreadful -rapidity. Nearly 400,000 quintals of nitrate in the stores at Iquique -and the adjacent ports of Molle and Pisagua were destroyed. The British -barque _Caprera_ and a German barque sank, and all the coasting craft -and small boats in the harbour were broken to pieces and drifted about -in every direction. - -At Chanavaya, a small town at the guano-loading dépôt known as Pabellon -de Pica, only two houses were left standing out of four hundred. Here -the earthquake shock was specially severe. In some places the earth -opened in crevices seventeen yards deep and the whole surface of the -ground was changed. - -At Punta de Eobos two vessels were lost, and fourteen ships more -or less damaged, by the wave. Antofagasta, Mexillones, Tocopilla, -and Cobigo, on the Bolivian coast, suffered simultaneously from the -earthquake and the sea-wave. The sea completely swept the business -portion of Antofagasta during four hours. Here a singular phenomenon -was noticed. For some time the atmosphere was illuminated with a ruddy -glow. It was supposed that this light came from the volcano of San -Pedro de Atacama, a few leagues inland from Antofagasta. A somewhat -similar phenomenon was noticed at Tacna during the earthquake of -August, 1868. About three hours after the earthquake an intensely -brilliant light made its appearance above the neighbouring mountains. -It lasted fully half an hour, and was ascribed to the eruption of some -as yet unknown volcano. - -As to the height of the great wave along this part of the shore-line -of South America, the accounts vary. According to those which are best -authenticated, it would seem as though the wave exceeded considerably -in height that which flowed along the Peruvian, Bolivian, and Chilian -shores in August, 1868. At Huaniles the wave was estimated at sixty -feet in height, at Mexillones, where the wave, as it passed southwards, -ran into Mexillones Bay, it reached a height of sixty-five feet. -Two-thirds of the town were completely obliterated, wharves, railway -stations, distilleries, etc., all swallowed up by the sea. - -The shipping along the Peruvian and Bolivian coast suffered terribly. -The list of vessels lost or badly injured at Pabellon de Pica alone, -reads like the list of a fleet. - -I have been particular in thus describing the effects produced by the -earthquake and sea-wave on the shores of South America, in order that -the reader may recognize in the disturbance produced there the real -origin of the great wave which a few hours later reached the Sandwich -Isles, 5000 miles away. Doubt has been entertained respecting the -possibility of a wave, other than the tidal-wave, being transmitted -right across the Pacific. Although in August, 1868, the course of the -great wave which swept from some region near Peru, not only across -the Pacific, but in all directions over the entire ocean, could be -clearly traced, there were some who considered the connection between -the oceanic phenomena and the Peruvian earthquake a mere coincidence. -It is on this account perhaps chiefly that the evidence obtained in -May, 1876, is most important. It is interesting, indeed, as showing -how tremendous was the disturbance which the earth’s frame must -then have undergone. It would have been possible, however, had we -no other evidence, for some to have maintained that the wave which -came in upon the shores of the Sandwich Isles a few hours after the -earthquake and sea disturbance in South America was in reality an -entirely independent phenomenon. But when we compare the events which -happened in May, 1876, with those of August, 1868, and perceive their -exact similarity, we can no longer reasonably entertain any doubt of -the really stupendous fact that _the throes of the earth in and near -Peru are of sufficient energy to send oceanic waves right across the -Pacific_,—waves, too, of such enormous height at starting, that, -after travelling with necessarily diminishing height the whole way -to Hawaii, they still rose and fell through thirty-six feet The real -significance of this amazing oceanic disturbance is exemplified by the -wave circles which spread around the spot where a stone has fallen into -a smooth lake. We know how, as the circles widen, the height of the -wave grows less and less, until, at no great distance from the centre -of disturbance, the wave can no longer be discerned, so slight is the -slope of its advancing and following faces. How tremendous, then, must -have been the upheaval of the bed of ocean by which wave-circles were -sent across the Pacific, retaining, after travelling 5000 miles from -the centre of disturbance, the height of a two-storied house! In 1868, -indeed, we know that the wave travelled very much further, reaching the -shores of Japan, of New Zealand, and of Australia, even if it did not -make its way through the East Indian Archipelago to the Indian Ocean, -as some observations seem to show. Although no news has been received -which would justify us in believing that the wave of May, 1876, -produced corresponding effects at such great distances from the centre -of disturbance, it must be remembered that the dimensions of the wave -when it reached the Sandwich Isles fell far short of those of the great -wave of August 13–14, 1868. - -It will be well to make a direct comparison between the waves of May, -1876, and August, 1868, in this respect, as also with regard to the -rate at which they would seem to have traversed the distance between -Peru and Hawaii. On this last point, however, it must be noted that -we cannot form an exact opinion until we have ascertained the real -region of Vulcanian disturbance on each occasion. It is possible that -a careful comparison of times, and of the direction in which the wave -front advanced upon different shores, might serve to show where this -region lay. I should not be greatly surprised to learn that it was far -from the continent of South America. - -The great wave reached the Sandwich Isles between four and five on the -morning of May 10, corresponding to about five hours later of Peruvian -time. An oscillation only was first observed at Hilo, on the east coast -of the great southern island of Hawaii, the wave itself not reaching -the village till about a quarter before five. The greatest difference -between the crest and trough of the wave was found to be thirty-six -feet here; but at the opposite side of the island, in Kealakekua Bay -(where Captain Cook was killed), amounted only to thirty feet. In -other places the difference was much less, being in some only three -feet, a circumstance doubtless due to interference, waves which have -reached the same spot along different courses chancing so to arrive -that the crest of one corresponded with the trough of the other, so -that the resulting wave was only the difference of the two. We must -explain, however, in the same way, the highest waves of thirty-six to -forty feet, which were doubtless due to similar interference, crest -agreeing with crest and trough with trough, so that the resulting wave -was the sum of the two which had been divided, and had reached the -same spot along different courses. It would follow that the higher of -the two waves was about twenty-one feet high, the lower about eighteen -feet high; but as some height would be lost in the encounter with the -shore-line, wherever it lay, on which the waves divided, we may fairly -assume that in the open ocean, before reaching the Sandwich group, the -wave had a height of nearly thirty feet from trough to crest. We read, -in accordance with this explanation, that “the regurgitations of the -sea were violent and complex, and continued through the day.” - -The wave, regarded as a whole, seems to have reached all the islands at -the same time. Since this has not been contradicted by later accounts, -we are compelled to conclude that the wave reached the group with its -front parallel to the length of the group, so that it must have come -(arriving as it did from the side towards which Hilo lies) from the -north-east It was, then, not the direct wave from Peru, but the wave -reflected from the shores of California, which produced the most marked -effects. We can understand well, this being so, that the regurgitations -of the sea were complex. Any one who has watched the inflow of waves -on a beach so lying within an angle of the line that while one set of -waves comes straight in from the sea, another thwart set comes from the -shore forming the other side of the angle, will understand how such -waves differ from a set of ordinary rollers. The crests of the two -sets form a sort of network, ever changing as each set rolls on; and -considering any one of the four-cornered meshes of this wave-net, the -observer will notice that while the middle of the raised sides rises -little above the surrounding level, because here the crests of one set -cross the troughs of the other, the corners of each quadrangle are -higher than they would be in either set taken separately, while the -middle of the four-cornered space is correspondingly depressed. The -reason is that at the corners of the wave-net crests join with crests -to raise the water surface, while in the middle of the net (not the -middle of the sides, but the middle of the space enclosed by the four -sides) trough joins with trough to depress the water surface.[24] - -We must take into account the circumstance that the wave which reached -Hawaii in May, 1876, was probably reflected from the Californian coast, -when we endeavour to determine the rate at which the sea disturbance -was propagated across the Atlantic. The direct wave would have come -sooner, and may have escaped notice because arriving in the night-time, -as it would necessarily have done if a wave which travelled to -California, and thence, after reflection, to the Sandwich group arrived -there at a quarter before five in the morning following the Peruvian -earthquake. We shall be better able to form an opinion on this point -after considering what happened in August, 1868. - -The earth-throe on that occasion was felt in Peru about five minutes -past five on the evening of August 13. Twelve hours later, or shortly -before midnight, August 13, Sandwich Island time (corresponding to -5 p.m., August 14, Peruvian time), the sea round the group of the -Sandwich Isles rose in a surprising manner, “insomuch that many thought -the islands were sinking, and would shortly subside altogether beneath -the waves. Some of the smaller islands were for a time completely -submerged. Before long, however, the sea fell again, and as it did so -the observers found it impossible to resist the impression that the -islands were rising bodily out of the water. For no less than three -days this strange oscillation of the sea continued to be experienced, -the most remarkable ebbs and floods being noticed at Honolulu, on the -island of Woahoo.” - -The distance between Honolulu and Arica is about 6300 statute miles; -so that, if the wave travelled directly from the shores of Peru to the -Sandwich Isles, it must have advanced at an average rate of about 525 -miles an hour (about 450 knots an hour). This is nearly half the rate -at which the earth’s surface near the equator is carried round by the -earth’s rotation, or is about the rate at which parts in latitude 62 or -63 degrees north are carried round by rotation; so that the motion of -the great wave in 1868 was fairly comparable with one of the movements -which we are accustomed to regard as cosmical. I shall presently have -something more to say on this point. - -Now in May, 1876, as we have seen, the wave reached Hawaii at about a -quarter to five in the morning, corresponding to about ten, Peruvian -time. Since, then, the earthquake was felt in Peru at half-past eight -on the previous evening, it follows that the wave, if it travelled -directly from Peru, must have taken about 13½ hours—or an hour and a -half longer, in travelling from Peru to the Sandwich Isles, than it -took in August, 1868. This is unlikely, because ocean-waves travel -nearly at the same rate in the same parts of the ocean, whatever -their dimensions, so only that they are large. We have, then, in the -difference of time occupied by the wave in May, 1876, and in August, -1868, in reaching Hawaii, some confirmation of the result to which we -were led by the arrival of the wave simultaneously at all the islands -of the Sandwich group—the inference, namely, that the observed wave -had reached these islands after reflection from the Californian -shore-line. As the hour when the direct wave probably reached Hawaii -was about a quarter past three in the morning, when not only was it -night-time but also a time when few would be awake to notice the rise -and fall of the sea, it seems not at all improbable that the direct -wave escaped notice, and that the wave actually observed was the -reflected wave from California. The direction, also, in which the -oscillation was first observed corresponds well with this explanation. - -It is clear that the wave which traversed the Pacific in May, 1876, -was somewhat inferior in size to that of August, 1868, which therefore -still deserves to be called (as I then called it) the greatest sea-wave -ever known. The earthquake, indeed, which preceded the oceanic -disturbance of 1868 was far more destructive than that of May, 1876, -and the waves which came in upon the Peruvian and Bolivian shores were -larger. Nevertheless, the wave of May, 1876, was not so far inferior to -that of August, 1868, but that its course could be traced athwart the -entire extent of the Pacific Ocean. - -When we consider the characteristic features of the Peruvian and -Chilian earthquakes, and especially when we note how wide is the extent -of the region over which their action is felt in one way or another, -it can scarcely be doubted that the earth’s Vulcanian energies are at -present more actively at work throughout that region than in any other. -There is nothing so remarkable, one may even say so stupendous, in -the history of subterranean disturbance as the alternation of mighty -earth-throes by which, at one time, the whole of the Chilian Andes seem -disturbed and anon the whole of the Peruvian Andes. In Chili scarcely -a year ever passes without earthquakes, and the same may be said of -Peru; but so far as great earthquakes are concerned the activity of the -Peruvian region seems to synchronize with the comparative quiescence -of the Chilian region, and _vice versâ_. Thus, in 1797, the terrible -earthquake occurred which is known as the earthquake of Riobamba, which -affected the entire Peruvian earthquake region. Thirty years later -a series of tremendous throes shook the whole of Chili, permanently -elevating its long line of coast to the height of several feet. During -the last twelve years the Peruvian region has in turn been disturbed by -great earthquakes. It should be added that between Chili and Peru there -is a region about five hundred miles in length in which scarcely any -volcanic action has been observed. And singularly enough, “this very -portion of the Andes, to which one would imagine that the Peruvians and -Chilians would fly as to a region of safety, is the part most thinly -inhabited; insomuch that, as Von Buch observes, it is in some places -entirely deserted.” - -One can readily understand that this enormous double region of -earthquakes, whose oscillations on either side of the central region -of comparative rest may be compared to the swaying of a mighty see-saw -on either side of its point of support, should be capable of giving -birth to throes propelling sea-waves across the Pacific Ocean. The -throe actually experienced at any given place is relatively but an -insignificant phenomenon: it is the disturbance of the entire region -over which the throe is felt which must be considered in attempting -to estimate the energy of the disturbing cause. The region shaken by -the earthquake of 1868, for instance, was equal to at least a fourth -of Europe, and probably to fully one-half. From Quito southwards as -far as Iquique—or along a full third part of the length of the South -American Andes—the shock produced destructive effects. It was also -distinctly felt far to the north of Quito, far to the south of Iquique, -and inland to enormous distances. The disturbing forces which thus -shook 1,000,000 square miles of the earth’s surface must have been of -almost inconceivable energy. If directed entirely to the upheaval of a -land region no larger than England, those forces would have sufficed -to have destroyed utterly every city, town, and village within such a -region; if directed entirely to the upheaval of an oceanic region, they -would have been capable of raising a wave which would have been felt -on every shore-line of the whole earth. Divided even between the ocean -on the one side and a land region larger than Russia in Europe on the -other, those Vulcanian forces shook the whole of the land region, and -sent athwart the largest of our earth’s oceans a wave which ran in upon -shores 10,000 miles from the centre of disturbance with a crest thirty -feet high. Forces such as these may fairly be regarded as cosmical; -they show unmistakably that the earth has by no means settled down into -that condition of repose in which some geologists still believe. We -may ask with the late Sir Charles Lyell whether, after contemplating -the tremendous energy thus displayed by the earth, any geologist will -continue to assert that the changes of relative level of land and sea, -so common in former ages of the world, have now ceased? and agree -with him that if, in the face of such evidence, a geologist persists -in maintaining this favourite dogma, it would be vain to hope, by -accumulating proofs of similar convulsions during a series of ages, to -shake the tenacity of his conviction— - - “Si fractus illabatur orbis, - Impavidum ferient ruinæ.” - -But there is one aspect in which such mighty sea-waves as, in 1868 and -again in May, 1876, have swept over the surface of our terrestrial -oceans, remains yet to be considered. - -The oceans and continents of our earth must be clearly discernible from -her nearer neighbours among the planets—from Venus and Mercury on the -inner side of her path around the sun, and from Mars (though under -less favourable conditions) from the outer side. When we consider, -indeed, that the lands and seas of Mars can be clearly discerned with -telescopic aid from our earth at a distance of forty millions of miles, -we perceive that our earth, seen from Venus at little more than half -this distance, must present a very interesting appearance. Enlarged, -owing to greater proximity, nearly fourfold, having a diameter nearly -twice as great as that of Mars, so that at the same distance her disc -would seem more than three times as large, more brightly illuminated -by the sun in the proportion of about five to two, she would shine -with a lustre exceeding that of Mars, when in full brightness in the -midnight sky, about thirty times; and all her features would of course -be seen with correspondingly increased distinctness. Moreover, the -oceans of our earth are so much larger in relative extent than those -of Mars, covering nearly three-fourths instead of barely one-half of -the surface of the world they belong to, that they would appeal as far -more marked and characteristic features than the seas and lakes of -Mars. When the Pacific Ocean, indeed, occupies centrally the disc of -the earth which at the moment is turned towards any planet, nearly the -whole of that disc must appear to be covered by the ocean. Under such -circumstances the passage of a wide-spreading series of waves over the -Pacific, at the rate of about 500 miles an hour, is a phenomenon which -could scarcely fail to be discernible from Venus or Mercury, if either -planet chanced to be favourably placed for the observation of the -earth—always supposing there were observers in Mercury or Venus, and -that these observers were provided with powerful telescopes. - -It must be remembered that the waves which spread over the Pacific -on August 13–14, 1868, and again on May 9–10, 1876, were not only of -enormous range in length (measured along crest or trough), but also -of enormous breadth (measured from crest to crest, or from trough -to trough). Were it otherwise, indeed, the progress of a wave forty -or fifty feet high (at starting, and thirty-five feet high after -travelling 6000 miles), at the rate of 500 miles per hour, must -have proved destructive to ships in the open ocean as well as along -the shore-line. Suppose, for instance, the breadth of the wave from -crest to crest one mile, then, in passing under a ship at the rate -of 500 miles per hour, the wave would raise the ship from trough to -crest—that is, through a height of forty feet—in one-thousandth -part of an hour (for the distance from trough to crest is but half -the breadth of the wave), or in less than four seconds, lowering it -again in the same short interval of time, lifting and lowering it -at the same rate several successive times. The velocity with which -the ship would travel upwards and downwards would be greatest when -she was midway in her ascent and descent, and would then be equal to -about the velocity with which a body strikes the ground after falling -from a height of four yards. It is hardly necessary to say that small -vessels subjected to such tossing as this would inevitably be swamped. -On even the largest ships the effect of such motion would be most -unpleasantly obvious. Now, as a matter of fact, the passage of the -great sea-wave in 1868 was not noticed at all on board ships in open -sea. Even within sight of the shore of Peru, where the oscillation of -the sea was most marked, the motion was such that its effects were -referred to the shore. We are told that observers on the deck of a -United States’ war steamer distinctly saw the “peaks of the mountains -in the chain of the Cordilleras wave to and fro like reeds in a storm;” -the fact really being that the deck on which they stood was swayed to -and fro. This, too, was in a part of the sea where the great wave had -not attained its open sea form, but was a rolling wave, because of the -shallowness of the water. In the open sea, we read that the passage -of the great sea-wave was no more noticed than is the passage of the -tidal-wave itself. “Among the hundreds of ships which were sailing upon -the Pacific when its length and breadth were traversed by the great -sea-wave, there was not one in which any unusual motion was perceived.” -The inference is clear, that the slope of the advancing and following -faces of the great wave was very much less than in the case above -imagined; in other words, that the breadth of the wave greatly exceeded -one mile—amounting, in fact, to many miles. - -Where the interval between the passage of successive wave-crests was -noted, we can tell the actual breadth of the wave. Thus, at the Samoan -Isles, in 1868, the crests succeeded each other at intervals of sixteen -minutes, corresponding to eight minutes between crest and trough. -But we have seen, that if the waves were one mile in breadth, the -corresponding interval would be only four seconds, or only one 120th -part of eight minutes: it follows, then, that the breadth of the great -wave, where it reached the Samoan Isles in 1868, was about 120 miles. - -Now a wave extending right athwart the Pacific Ocean, and having a -cross breadth of more than 120 miles, would be discernible as a marked -feature of the disc of our earth, seen under the conditions described -above, either from Mercury or Venus. It is true that the slope of -the wave’s advancing and following surfaces would be but slight, yet -the difference of the illumination under the sun’s rays would be -recognizable. Then, also, it is to be remembered that there was not -merely a single wave, but a succession of many waves. These travelled -also with enormous velocity; and though at the distance of even the -nearest planet, the apparent motion of the great wave, swift though -it was in reality, would be so far reduced that it would have to be -estimated rather than actually seen, yet there would be no difficulty -in thus perceiving it with the mind’s eye. The rate of motion indeed -would almost be exactly the same as that of the equatorial part of the -surface of Mars, in consequence of the planet’s rotation; and this -(as is well known to telescopists), though not discernible directly, -produces, even in a few minutes, changes which a good eye can clearly -recognize. We can scarcely doubt then that if our earth were so -situated at any time when one of the great waves generated by Peruvian -earthquakes in traversing the Pacific, that the hemisphere containing -this ocean were turned fully illuminated towards Venus (favourably -placed for observing her), the disturbance of the Pacific could be -observed and measured by telescopists on that planet. - -Unfortunately there is little chance that terrestrial observers will -ever be able to watch the progress of great waves athwart the oceans of -Mars, and still less that any disturbance of the frame of Venus should -become discernible to us by its effects. We can scarce even be assured -that there are lands and seas on Venus, so far as direct observation is -concerned, so unfavourably is she always placed for observation; and -though we see Mars under much more favourable conditions, his seas are -too small and would seem to be too shallow (compared with our own) for -great waves to traverse them such as could be discerned from the earth. - -Yet it is well to remember the possibility that changes may at times -take place in the nearer planets—the terrestrial planets, as they -are commonly called, Mars, Venus, and Mercury—such as telescopic -observation under favourable conditions might detect. Telescopists -have, indeed, described apparent changes, lasting only for a short -time, in the appearance of one of these planets, Mars, which may fairly -be attributed to disturbances affecting its surface in no greater -degree than the great Peruvian earthquakes have affected for a time the -surface of our earth. For instance, the American astronomer Mitchel -says that on the night of July 12, 1845, bright polar snows of Mars -exhibited an appearance never noticed at any preceding or succeeding -observation. In the very centre of the white surface appeared a -dark spot, which retained its position during several hours: on the -following evening not a trace of the spot could be seen. Again the same -observer says that on the evening of August 30, 1845, he observed for -the first time a small bright spot, nearly or quite round, projecting -out of the lower side of the polar spot. “In the early part of the -evening,” he says, “the small bright spot seemed to be partly buried -in the large one. After the lapse of an hour or more my attention was -again directed to the planet, when I was astonished to find a manifest -change in the position of the small bright spot. It had apparently -separated from the large spot, and the edges alone of the two were now -in contact, whereas when first seen they overlapped by an amount quite -equal to one-third of the diameter of the small one. This, however, -was merely an optical phenomenon, for on the next evening the spots -went through the same apparent changes as the planet went through the -corresponding part of its rotation. But it showed the spots to be real -ice masses. The strange part of the story is that in the course of a -few days the smaller spot, which must have been a mass of snow and ice -as large as Novaia Zemlia, gradually disappeared. Probably some great -shock had separated an enormous field of ice from the polar snows, and -it had eventually been broken up and its fragments carried away from -the Arctic regions by currents in the Martian oceans. It appears to -me that the study of our own earth, and of the changes and occasional -convulsions which affect its surface, gives to the observation of such -phenomena as I have just described a new interest. Or rather, perhaps, -it is not too much to say that the telescopic observations of the -planets derive their only real interest from such considerations. - -I may note in conclusion, that while on the one hand we cannot doubt -that the earth is slowly parting with its internal heat, and thus -losing century by century a portion of its Vulcanian energy, such -phenomena as the Peruvian earthquakes show that the loss of energy is -taking place so slowly that the diminution during many ages is almost -imperceptible. As I have elsewhere remarked, “When we see that while -mountain ranges were being upheaved or valleys depressed to their -present position, race after race and type after type lived out on the -earth the long lives which belong to races and to types, we recognize -the great work which the earth’s subterranean forces are still engaged -upon. Even now continents are being slowly depressed or upheaved, even -now mountain ranges are being raised to a different level, table-lands -are being formed, great valleys are being gradually scooped out; old -shore-lines shift their place, old soundings vary; the sea advances in -one place and retires in another; on every side nature’s plastic hand -is still at work, modelling and remodelling the earth, and making it -constantly a fit abode for those who dwell upon it.” - - - - -_STRANGE SEA CREATURES._ - - “We ought to make up our minds to dismiss as idle prejudices, - or, at least, suspend as premature, any preconceived notion of - what _might_, or what _ought to_, _be_ the order of nature, and - content ourselves with observing, as a plain matter of fact, what - _is_.”—Sir J. HERSCHEL, “Prelim. Disc.” page 79. - - -The fancies of men have peopled three of the four so-called elements, -earth, air, water, and fire, with strange forms of life, and have even -found in the salamander an inhabitant for the fourth. On land the -centaur and the unicorn, in the air the dragon and the roc, in the -water tritons and mermaids, may be named as instances among many of the -fabulous creatures which have been not only imagined but believed in -by men of old times. Although it may be doubted whether men have ever -invented any absolutely imaginary forms of life, yet the possibility -of combining known forms into imaginary, and even impossible, forms, -must be admitted as an important element in any inquiry into the origin -of ideas respecting such creatures as I have named. One need only look -through an illuminated manuscript of the Middle Ages to recognize the -readiness with which imaginary creatures can be formed by combining, -or by exaggerating, the characteristics of known animals. Probably -the combined knowledge and genius of all the greatest zoologists of -our time would not suffice for the invention of an entirely new form -of animal which yet should be zoologically possible; but to combine -the qualities of several existent animals in a single one, or to -conceive an animal with some peculiarity abnormally developed, is -within the capacity of persons very little acquainted with zoology, -nay, is perhaps far easier to such persons than it would be to an -Owen, a Huxley, or a Darwin. In nearly every case, however, the purely -imaginary being is to be recognized by the utter impossibility of -its actual existence. If it be a winged man, arms and wings are both -provided, but the pectoral muscles are left unchanged. A winged horse, -in like manner, is provided with wings, without any means of working -them. A centaur, as in the noble sculptures of Phidias, has the upper -part of the trunk of a man superadded, not to the hind quarters of a -horse or other quadruped, but to the entire trunk of such an animal, -so that the abdomen of the human figure lies _between_ the upper half -of the human trunk and the corresponding part of the horse’s trunk, -an arrangement anatomically preposterous. Without saying that every -fabulous animal which was anatomically and zoologically possible, had a -real antitype, exaggerated though the fabulous form may have been, we -must yet admit that errors so gross marked the conception of all the -really imaginary animals of antiquity, that any fabulous animal found -to accord fairly well with zoological possibilities may be regarded, -with extreme probability, as simply the exaggerated presentation of -some really existent animal. The inventors of centaurs, winged and -man-faced bulls, many-headed dogs, harpies, and so forth, were utterly -unable to invent a possible new animal, save by the merest chance, the -probability of which was so small that it may fairly be disregarded. - -This view of the so-called fabulous animals of antiquity has been -confirmed by the results of modern zoological research. The merman, -zoologically possible (not in all details, of course, but generally), -has found its antitype in the dugong and the manatee; the roc in the -condor, or perhaps in those extinct species whose bones attest their -monstrous proportions; the unicorn in the rhinoceros; even the dragon -in the pterodactyl of the green-sand; while the centaur, the minotaur, -the winged horse, and so forth, have become recognized as purely -imaginary creatures, which had their origin simply in the fanciful -combination of known forms, no existent creatures having even suggested -these monstrosities. - -It is not to be wondered at that the sea should have been more prolific -in monstrosities and in forms whose real nature has been misunderstood. -Land animals cannot long escape close observation. Even the most -powerful and ferocious beasts must succumb in the long run to man, and -in former ages, when the struggle was still undecided between some race -of animals and savage man, individual specimens of the race must often -have been killed, and the true appearance of the animal determined. -Powerful winged animals might for a longer time remain comparatively -mysterious creatures even to those whom they attacked, or whose flocks -they ravaged. A mighty bird, or a pterodactylian creature (a late -survivor of a race then fast dying out), might swoop down on his prey -and disappear with it too swiftly to be made the subject of close -scrutiny, still less of exact scientific observation. Yet the general -characteristics even of such creatures would before long be known. -From time to time the strange winged monster would be seen hovering -over the places where his prey was to be found. Occasionally it would -be possible to pierce one of the race with an arrow or a javelin; and -thus, even in those remote periods when the savage progenitors of the -present races of man had to carry on a difficult contest with animals -now extinct or greatly reduced in power, it would become possible to -determine accurately the nature of the winged enemy. But with sea -creatures, monstrous, or otherwise, the case would be very different. -To this day we remain ignorant of much that is hidden beneath the -waves of the “hollow-sounding and mysterious main.” Of far the greater -number of sea creatures, it may truly be said that we never see any -specimens except by accident, and never obtain the body of any except -by very rare accident. Those creatures of the deep sea which we are -best acquainted with, are either those which are at once very numerous -and very useful as food or in some other way, or else those which are -very rapacious and thus expose themselves, by their attacks on men, -to counter-attack and capture or destruction. In remote times, when -men were less able to traverse the wide seas, when, on the one hand, -attacks from great sea creatures were more apt to be successful, -while, on the other, counter-attack was much more dangerous, still -less would be known about the monsters of the deep. Seen only for a -few moments as he seized his prey, and then sinking back into the -depths, a sea monster would probably remain a mystery even to those -who had witnessed his attack, while their imperfect account of what -they had seen would be modified at each repetition of the story, until -there would remain little by which the creature could be identified, -even if at some subsequent period its true nature were recognized. We -can readily understand, then, that among the fabulous creatures of -antiquity, even of those which represented actually existent races -incorrectly described, the most remarkable, and those zoologically -the least intelligible, would be the monsters of the deep sea. We can -also understand that even the accounts which originally corresponded -best with the truth would have undergone modifications much more -noteworthy than those affecting descriptions of land animals or winged -creatures—simply because there would be small chance of any errors -thus introduced being corrected by the study of freshly discovered -specimens. - -We may, perhaps, explain in this way the strange account given by -Berosus of the creature which came up from the Red Sea, having the body -of a fish but the front and head of a man. We may well believe that -this animal was no other than a dugong, or halicore (a word signifying -sea-maiden), a creature inhabiting the Indian Ocean to this day, and -which might readily find its way into the Red Sea. But the account of -the creature has been strangely altered from the original narrative, -if at least the original narrative was correct. For, according to -Berosus, the animal had two human feet which projected from each side -of the tail; and, still stranger, it had a human voice and human -language. “This strange monster sojourned among the rude people during -the day, taking no food, but retiring to the sea again at night, and -continued for some time teaching them the arts of civilized life.” A -picture of this stranger is said to have been preserved at Babylon -for many centuries. With a probable substratum of truth, the story in -its latest form is as fabulous as Autolycus’s “ballad of a fish that -appeared upon the coast, on Wednesday the fourscore of April, forty -thousand fathoms above water, and sang a ballad against the hard hearts -of maids.” - -It is singular, by the way, how commonly the power of speech, or at -least of producing sounds resembling speech or musical notes, was -attributed to the creature which imagination converted into a man-fish -or woman-fish. Dugongs and manatees make a kind of lowing noise, which -could scarcely be mistaken under ordinary conditions for the sound of -the human voice. Yet, not only is this peculiarity ascribed to the -mermaid and siren (the merman and triton having even the supposed power -of blowing on conch-shells), but in more recent accounts of encounters -with creatures presumably of the seal tribe and allied races, the same -feature is to be noticed. The following account, quoted by Mr. Gosse -from a narrative by Captain Weddell, the well-known geographer, is -interesting for this reason amongst others. It also illustrates well -the mixture of erroneous details (the offspring, doubtless, of an -excited imagination) with the correct description of a sea creature -actually seen:—“A boat’s crew were employed on Hall’s Island, when -one of the crew, left to take care of some produce, saw an animal -whose voice was musical. The sailor had lain down, and at ten o’clock -he heard a noise resembling human cries, and as daylight in these -latitudes never disappears at this season” (the Antarctic summer), -“he rose and looked around, but, on seeing no person, returned to -bed. Presently he heard the noise again; he rose a second time, but -still saw nothing. Conceiving, however, the possibility of a boat -being upset, and that some of the crew might be clinging to detached -rocks, he walked along the beach a few steps and heard the noise more -distinctly but in a musical strain. Upon searching around, he saw an -object lying on a rock a dozen yards from the shore, at which he was -somewhat frightened. The face and shoulders appeared of human form and -of a reddish colour; over the shoulders hung long green hair; the tail -resembled that of the seal, but the extremities of the arms he could -not see distinctly. The creature continued to make a musical noise -while he gazed about two minutes, and on perceiving him it disappeared -in an instant. Immediately, when the man saw his officer, he told this -wild tale, and to add weight to his testimony (being a Romanist) he -made a cross on the sand, which he kissed, as making oath to the truth -of his statement. When I saw him he told the story in so clear and -positive a manner, making oath to its truth, that I concluded he must -really have seen the animal he described, or that it must have been the -effects of a disturbed imagination.” - -In this story all is consistent with the belief that the sailor saw -an animal belonging to the seal family (of a species unknown to him), -except the green hair. But the hour was not very favourable to the -discerning of colour, though daylight had not quite passed away, and as -Gosse points out, since golden-yellow fur and black fur are found among -Antarctic seals, the colours may be intermingled in some individuals, -producing an olive-green tint, which, by contrast with the reddish -skin, might be mistaken for a full green. Considering that the man had -been roused from sleep and was somewhat frightened, he would not be -likely to make very exact observations. It will be noticed that it was -only at first that he mistook the sounds made by the creature for human -cries; afterwards he heard only the same _noise_, but in a musical -strain. Now with regard to the musical sounds said to have been uttered -by this creature, and commonly attributed to creatures belonging to -families closely allied to the seals, I do not know that any attempt -has yet been made to show that these families possess the power of -emitting sounds which can properly be described as musical. It is quite -possible that the Romanist sailor’s ears were not very nice, and that -any sound softer than a bellow seemed musical to him. Still, the idea -suggests itself that possibly seals, like some other animals, possess a -note not commonly used, but only as a signal to their mates, and never -uttered when men or other animals are known to be near. It appears -to me that this is rendered probable by the circumstance that seals -are fond of music. Darwin refers to this in his treatise on Sexual -Selection (published with his “Descent of Man”), and quotes a statement -to the effect that the fondness of seals for music “was well known to -the ancients, and is often taken advantage of by hunters to the present -day.” The significance of this will be understood from Darwin’s remark -immediately following, that “with all these animals, the males of which -during the season of courtship incessantly produce musical notes or -mere rhythmical sounds, we must believe that the females are able to -appreciate them.” - -The remark about the creature’s arms seems strongly to favour the -belief that the sailor intended his narrative to be strictly truthful. -Had he wished to excite the interest of his comrades by a marvellous -story, he certainly would have described the creature as having -well-developed human hands. - -Less trustworthy by far seem some of the stories which have been told -of animals resembling the mermaid of antiquity. It must always be -remembered, however, that in all probability we know very few among the -species of seals and allied races, and that some of these species may -present, in certain respects and perhaps at a certain age, much closer -resemblance to the human form than the sea-lion, seal, manatee, or -dugong. - -We cannot, for instance, attach much weight to the following story -related by Hudson, the famous navigator:—“One of our company, looking -overboard, saw a mermaid and calling up some of the company to see her, -one more came up, and by that time she was come close to the ship’s -side, looking earnestly on the men. A little after a sea came and -overturned her. From the navel upward her back and breasts were like a -woman’s, as they say that saw her; her body as big as one of us; her -skin very white; and long hair hanging down behind, of colour black. In -her going down they saw her tail, which was like the tail of a porpoise -and speckled like a mackerel.” If Hudson himself had seen and thus -described the creature it would have been possible to regard the story -with some degree of credence; but his account of what Thomas Hilles and -Robert Rayner, men about whose character for veracity we know nothing, -_said_ they saw, is of little weight. The skin very white, and long -hair hanging down behind, are especially suspicious features of the -narrative; and were probably introduced to dispose of the idea, which -others of the crew may have advanced, that the creature was only some -kind of seal after all. The female seal (_Phoca Greenlandica_ is the -pretty name of the animal) is not, however, like the male, tawny grey, -but dusky white, or yellowish straw-colour, with a tawny tint on the -back. The young alone could be called “very white.” They are so white -in fact as scarcely to be distinguishable when lying on ice and snow, -a circumstance which, as Darwin considers, serves as a protection for -these little fellows. - -The following story, quoted by Gosse from Dr. Robert Hamilton’s able -“History of the Whales and Seals,” compares favourably in some respects -with the last narrative:—“It was reported that a fishing-boat off the -island of Yell, one of the Shetland group, had captured a mermaid by -its getting entangled in the lines! The statement is, that the animal -is about three feet long, the upper part of the body resembling the -human, with protuberant mammæ like a woman; the face, the forehead, -and neck, were short, and resembling those of a monkey; the arms, -which were small, were kept folded across the breast; the fingers were -distinct, not webbed; a few stiff long bristles were on the top of -the head, extending down to the shoulders, and these it could erect -and depress at pleasure, something like a crest. The inferior part of -the body was like a fish. The skin was smooth and of a grey colour. -It offered no resistance, nor attempted to bite, but uttered a low, -plaintive sound. The crew, six in number, took it within their boat; -but superstition getting the better of curiosity, they carefully -disentangled it from the lines and a hook which had accidentally -fastened in the body, and returned it to its native element. It -instantly dived, descending in a perpendicular direction.” “They had -the animal for three hours within the boat; the body was without scales -or hair; of a silvery grey colour above, and white below, like the -human skin; no gills were observed, nor fins on the back or belly. The -tail was like that of the dog-fish; the mammæ were about as large as -those of a woman; the mouth and lips were very distinct, and resembled -the human.” - -This account, if accepted in all its details, would certainly indicate -that an animal of some species before unknown had been captured. But it -is doubtful how much reliance can be placed on the description of the -animal. Mr. Gosse, commenting upon the case, says that the fishermen -cannot have been affected by fear in such sort that their imagination -exaggerated the resemblance of the creature to the human form. “For the -mermaid,” he says, “is not an object of terror to the fishermen; it -is rather a welcome guest, and danger is to be apprehended only from -its experiencing bad treatment.” But then this creature had not been -treated as a specially welcome guest. The crew had captured it; and -probably not without some degree of violence; for though it offered -no resistance it uttered a plaintive cry. And that hook which “had -accidentally fastened in the body” has a very suspicious look. If the -animal could have given its own account of the capture, probably the -hook would not have been found to have fastened in the body altogether -by accident. Be this as it may, the fishermen were so far frightened -that superstition got the better of curiosity; so that, as they were -evidently very foolish fellows, their evidence is scarcely worth much. -There are, however, only two points in their narrative which do not -seem easily reconciled with the belief that they had captured a rather -young female of a species closely allied to the common seal—the -distinct unwebbed fingers and the small arms folded across the breast. -Other points in their description suggest marked differences in -degree from the usual characteristics of the female seal; but these -two alone seem to differ absolutely in kind. Considering all the -circumstances of the narrative, we may perhaps agree with Mr. Gosse to -this extent, that, combined with other statements, the story induces a -strong suspicion that the northern seas may hold forms of life as yet -uncatalogued by science. - -The stories which have been related about monstrous cuttle-fish -have only been fabulous in regard to the dimensions which they have -attributed to these creatures. Even in this respect it has been shown, -quite recently, that some of the accounts formerly regarded as fabulous -fell even short of the truth. Pliny relates, for instance, that the -body of a monstrous cuttle-fish, of a kind known on the Spanish coast, -weighed, when captured, 700 lbs., the head the same, the arms being 30 -feet in length. The entire weight would probably have amounted to about -2000 lbs. But we shall presently see that this weight has been largely -exceeded by modern specimens. It was, however, in the Middle Ages that -the really fabulous cuttle-fish flourished—the gigantic kraken, “liker -an island than an animal,” according to credulous Bishop Pontoppidan, -and able to destroy in its mighty arms the largest galleons and war -ships of the fourteenth and fifteenth centuries. - -It is natural that animals really monstrous should be magnified by the -fears of those who have seen or encountered them, and still further -magnified afterwards by tradition. Some specimens of cuttle-fish which -have been captured wholly, or in part, indicate that this creature -sometimes attains such dimensions that but little magnifying would -be needed to suggest even the tremendous proportions of the fabulous -kraken. In 1861, the French war-steamer _Alecton_ encountered a -monstrous cuttle, on the surface of the sea, about 120 miles north-east -of Teneriffe. The crew succeeded in slipping a noose round the body, -but unfortunately the rope slipped, and, being arrested by the tail -fin, pulled off the tail. This was hauled on board, and found to weigh -over 40 lbs. From a drawing of the animal, the total length without -the arms was estimated at 50 feet, and the weight at 4000 lbs., nearly -twice the weight of Pliny’s monstrous cuttle-fish, long regarded as -fabulous. In one respect this creature seems to have been imperfect, -the two long arms usually possessed by cuttle-fish of the kind being -wanting. Probably it had lost these long tentacles in a recent -encounter with some sea enemy, perhaps one of its own species. Quite -possibly it may have been such recent mutilation which exposed this -cuttle-fish to successful attack by the crew of the _Alecton_. - -A cuttle-fish of about the same dimensions was encountered by two -fishermen in 1873, in Conception Bay, Newfoundland. When they attacked -it, the creature threw its long arms across the boat, but the fishermen -with an axe cut off these tentacles, on which the cephalopod withdrew -in some haste. One of the arms was preserved, after it had lost about -6 feet of its length. Even thus reduced it measured 19 feet; and as -the fishermen estimate that the arm was struck off about 10 feet from -the body, it follows that the entire length of the limb must have -been about 35 feet. They estimated the body at 60 feet in length and -5 feet in diameter—a monstrous creature! It was fortunate for these -fishermen that they had an axe handy for its obtrusive tentacles, as -with so great a mass and the great propulsive power possessed by all -cephalopods, it might readily have upset their small boat. Once in the -water, they would have been at the creature’s mercy—a quality which, -by all accounts, the cuttle-fish does not possess to any remarkable -extent. - -Turn we, however, from the half fabulous woman-fish, and the -exaggeratedly monstrous cuttle-fish, to the famous sea-serpent, held -by many to be the most utterly fabulous of all fabled creatures, while -a few, including some naturalists of distinction, stoutly maintain -that the creature has a real existence, though whether it be rightly -called a sea-serpent or not is a point about which even believers are -extremely doubtful. - -It may be well, in the first place, to remark that in weighing the -evidence for and against the existence of this creature, and bearing -on the question of its nature (if its existence be admitted), we ought -not to be influenced by the manifest falsity of a number of stories -relating to supposed encounters with this animal. It is probable -that, but for these absurd stories, the well-authenticated narratives -relating to the creature, whatever it may be, which has been called -the sea-serpent, would have received much more attention than has -heretofore been given to them. It is also possible that some narratives -would have been published which have been kept back from the fear -lest a truthful (though possibly mistaken) account should be classed -with the undoubted untruths which have been told respecting the great -sea-serpent. It cannot be denied that in the main the inventions and -hoaxes about the sea-serpent have come chiefly from American sources. -It is unfortunately supposed by too many of the less cultured sons of -America that (to use Mr. Gosse’s expression) “there is somewhat of wit -in gross exaggerations or hoaxing inventions.” Of course an American -gentleman—using the word “in that sense in which every man may be -a gentleman,” as Twemlow hath it—would as soon think of uttering a -base coin as a deliberate untruth or foolish hoax. But it is thought -clever, by not a few in America who know no better, to take any one in -by an invention. Some, perhaps but a small number, of the newspapers -set a specially bad example in this respect, giving room in their -columns for pretended discoveries in various departments of science, -elaborate accounts of newly discovered animals, living or extinct, and -other untruths which would be regarded as very disgraceful indeed by -English editors. Such was the famous “lunar hoax,” published in the -New York _Sun_ some forty years ago; such the narrative, in 1873, of a -monstrous fissure which had been discerned in the body of the moon, and -threatened to increase until the moon should be cloven into two unequal -parts; such the fables which have from time to time appeared respecting -the sea-serpent. But it would be as unreasonable to reject, because -of these last-named fables, the narratives which have been related by -quiet, truth-loving folk, and have borne close and careful scrutiny, as -it would be to reject the evidence given by the spectroscope respecting -the existence of iron and other metals in the sun because an absurd -story had told how creatures in the moon had been observed to make use -of metal utensils or to adorn the roofs of their temples with metallic -imitations of wreathed flames. - -The oldest accounts on record of the appearance of a great sea creature -resembling a serpent are those quoted by Bishop Pontoppidan, in his -description of the natural history of his native country, Norway. -Amongst these was one confirmed by oath taken before a magistrate -by two of the crew of a ship commanded by Captain de Ferry, of the -Norwegian navy. The captain and eight men saw the animal, near Molde, -in August, 1747. They described it as of the general form of a serpent, -stretched on the surface in receding coils (meaning, probably, the -shape assumed by the neck of a swan when the head is drawn back). The -head, which resembled that of a horse, was raised two feet above the -water. - -In August, 1817, a large marine animal, supposed to be a serpent, was -seen near Cape Ann, Massachusetts. Eleven witnesses of good reputation -gave evidence on oath before magistrates. One of these magistrates had -himself seen the creature, and corroborated the most important points -of the evidence given by the eleven witnesses. The creature had the -appearance of a serpent, dark brown in colour (some said mottled), -with white under the head and neck. Its length was estimated at from -50 to 100 feet. The head was in shape like a serpent’s, but as large -as a horse’s. No mane was noticed. Five of the witnesses deposed -to protuberances on the back; four said the back was straight; the -other two gave no opinion on this point. The magistrate who had seen -the animal considered the appearance of protuberances was due to the -bendings of the body while in rapid motion. - -In 1848, when the captain of the British frigate _Dædalus_ had -published an account of a similar animal seen by him and several of his -officers and crew, the Hon. Colonel T. H. Perkins, of Boston, who had -seen the animal on the occasion just mentioned in 1817, gave an account -(copied from a letter written in 1820) of what he had witnessed. It -is needless to quote those points which correspond with what has -been already stated. Colonel Perkins noticed “an appearance in the -front of the head like a single horn, about nine inches to a foot in -length, shaped like a marlinspike, which will presently be explained. -I left the place,” he proceeds, “fully satisfied that the reports in -circulation, though differing in details, were essentially correct.” -He relates how a person named Mansfield, “one of the most respectable -inhabitants of the town, who had been such an unbeliever in the -existence of this monster that he had not given himself the trouble to -go from his house to the harbour when the report was first made,” saw -the animal from a bank overlooking the harbour. Mr. Mansfield and his -wife agreed in estimating the creature’s length at 100 feet. Several -crews of coasting vessels saw the animal, _in some instances within a -few yards_. “Captain Tappan,” proceeds Colonel Perkins, “a person well -known to me, saw him with his head above water two or three feet, at -times moving with great rapidity, at others slowly. He also saw what -explained the appearance which I have described of a horn on the front -of the head. This was doubtless what was observed by Captain Tappan to -be the tongue, thrown in an upright position from the mouth, and having -the appearance which I have given to it. One of the revenue cutters, -whilst in the neighbourhood of Cape Ann, had an excellent view of him -at a few yards’ distance; he moved slowly, and upon the appearance of -the vessel sank and was seen no more.” - -Fifteen years later, in May 1833, five British officers—Captain -Sullivan, Lieutenants Maclachlan and Malcolm of the Rifle Brigade, -Lieutenant Lyster of the Artillery, and Mr. Snee of the Ordnance—when -cruising in a small yacht off Margaret’s Bay, not far from Halifax, -“saw the head and neck of some denizen of the deep, precisely like -those of a common snake, in the act of swimming, the head so elevated -and thrown forward by the curve of the neck as to enable us to see -the water under and beyond it.” They judged its length to exceed -80 feet. “There could be no mistake nor delusion, and we were all -perfectly satisfied that we had been favoured with a view of the ‘true -and veritable sea-serpent,’ which had been generally considered to -have existed only in the brain of some Yankee skipper, and treated -as a tale not entitled to belief.” Dowling, a man-of-war’s man they -had along with them, made the following unscientific but noteworthy -comment: “Well, I’ve sailed in all parts of the world, and have seen -rum sights too in my time, but this is the queerest thing I ever -see.” “And surely,” adds Captain Sullivan, “Jack Dowling was right.” -The description of the animal agrees in all essential respects with -previous accounts, but the head was estimated at about six feet in -length—considerably larger, therefore, than a horse’s head. - -But unquestionably the account of the sea-serpent which has commanded -most attention was that given by the captain, officers, and crew of -the British frigate _Dædalus_, Captain M’Quhæ, in 1848. The _Times_ -published on October 9, 1848, a paragraph stating that the sea-serpent -had been seen by the captain and most of the officers and crew of this -ship, on her passage home from the East Indies. The Admiralty inquired -at once into the truth of the statement, and the following is abridged -from Captain M’Quhæ’s official reply, addressed to Admiral Sir W. H. -Gage. - -“Sir,—In reply to your letter, requiring information as to the truth -of a statement published in the _Times_ newspaper, of a sea-serpent of -extraordinary dimensions having been seen from the _Dædalus_, I have -the honour to inform you that at 5 p.m., August 6 last, in latitude 24° -44´ S., longitude 9° 22´ E., the weather dark and cloudy, wind fresh -from N.W., with long ocean swell from S.W., the ship on the port tack, -heading N.E. by N., Mr. Sartoris, midshipman, reported to Lieutenant -E. Drummond (with whom, and Mr. W. Barrett, the master, I was walking -the quarter-deck) something very unusual rapidly approaching the ship -from before the beam. The object was seen to be an enormous serpent, -with head and shoulders kept about four feet constantly above the -surface of the sea, as nearly as we could judge; at least 60 feet of -the animal was on the surface, no part of which length was used, so -far as we could see, in propelling the animal either by vertical or -horizontal undulation. It passed quietly, _but so closely under our lee -quarter that, had it been a man of my acquaintance, I should easily -have recognized his features with the naked eye_. It did not, while -visible, deviate from its course to the S.W., which it held on at the -pace of from 12 to 15 miles per hour, as if on some determined purpose. -The diameter of the serpent was from 15 to 16 inches behind the head, -which was, without any doubt, that of a snake. Its colour was a dark -brown, with yellowish white about the throat. It did not once, while -within the range of view from our glasses, sink below the surface. It -had no fins, but something like the mane of a horse, or rather a bunch -of sea-weed, washed about its back. It was seen by the quarter-master, -the boatswain’s mate, and the man at the wheel, in addition to myself -and the officers above-mentioned. I am having a drawing of the serpent -made from a sketch taken immediately after it was seen, which I hope to -have ready for my Lords Commissioners of the Admiralty by to-morrow’s -post.—Peter M’Quhæ, Captain.” - -The drawing here mentioned was published in the _Illustrated London -News_ for October 28, 1848, being there described as made “under the -supervision of Captain M’Quhæ, and his approval of the authenticity of -the details as to position and form.” - -The correspondence and controversy elicited by the statement of Captain -M’Quhæ were exceedingly interesting. It is noteworthy, at the outset, -that few, perhaps none, who had read the original statement, suggested -the idea of illusion, while it need hardly perhaps be said that no one -expressed the slightest doubt as to the _bona fides_ of Captain M’Quhæ -and his fellow-witnesses. These points deserve attention, because, -in recent times, the subject of the sea-serpent has been frequently -mentioned in public journals and elsewhere as though no accounts of -the creature had ever been given which had been entitled to credence. -I proceed to summarise the correspondence which followed M’Quhæ’s -announcement. The full particulars will be found in Mr. Gosse’s -interesting work, the “Romance of Natural History,” where, however, as -it seems to me, the full force of the evidence is a little weakened, -for all save naturalists, by the introduction of particulars not -bearing directly on the questions at issue. - -Among the earliest communications was one from Mr. J. D. M. Stirling, -a gentleman who, during a long residence in Norway, had heard repeated -accounts of the sea-serpent in Norwegian seas, and had himself seen a -fish or reptile at a distance of a quarter of a mile, which, examined -through a telescope, corresponded in appearance with the sea-serpent as -usually described. This communication was chiefly interesting, however, -as advancing the theory that the supposed sea-serpent is not a serpent -at all, but a long-necked plesiosaurian. This idea had been advanced -earlier, but without his knowledge, by Mr. E. Newman, the editor of -the _Zoologist_. Let us briefly inquire into the circumstances which -suggest the belief. - -If we consider the usual account of the sea-serpent, we find one -constant feature, which seems entirely inconsistent with the belief -that the creature can be a serpent. The animal has always shown a -large portion of its length, from 20 to 60 feet, above the surface -of the water, and without any evident signs of undulation, either -vertically or horizontally. Now, apart from all zoological evidence, -our knowledge of physical laws will not permit us to believe that the -portion thus visible above the surface was propelled by the undulations -of a portion concealed below the surface, unless this latter portion -largely exceeded the former in bulk. A true fish does not swim for any -length of time with any but a very small portion of its body above -water; probably large eels never show even a head or fin above water -for more than a few seconds when not at rest. Cetaceans, owing to the -layers of blubber which float them up, remain often for a long time -with a portion of their bulk out of the water, and the larger sort -often swim long distances with the head and fore-part out of water. -But, even then, the greater part of the creature’s bulk is under water, -and the driving apparatus, the anterior fins and the mighty tail, are -constantly under water (when the animal is urging its way horizontally, -be it understood). A sea creature, in fact, whatever its nature, which -keeps any considerable volume of its body out of water constantly, -while travelling a long distance, must of necessity have a much greater -volume all the time under water, and must have its propelling apparatus -under water. Moreover, if the propulsion is not effected by fins, -paddles, a great flat tail, or these combined, but by the undulations -of the animal’s own body, then the part out of water must of necessity -be affected by these undulations, unless it is very small in volume -and length compared with the part under water. I assert both these -points as matters depending on physical laws, and without fear that the -best-informed zoologist can adduce any instances to the contrary. It -is in fact physically impossible that such instances should exist. - -It would not be saying too much to assert that if the so-called -sea-serpent were really a serpent, its entire length must be nearer -1000 than 100 feet. This, of course, is utterly incredible. We are, -therefore, forced to the belief that the creature is not a serpent. -If it were a long-necked reptile, with a concealed body much bulkier -than the neck, the requirements of floatation would be satisfied; if -to that body there were attached powerful paddles, the requirements -of propulsion would be satisfied. The theory, then, suggested, first -by Mr. Newman, later but independently by Mr. Stirling, and advocated -since by several naturalists of repute, is simply that the so-called -sea-serpent is a modern representative of the long-necked plesiosaurian -reptile to which has been given the name of the _enaliosaurus_. -Creatures of this kind prevailed in that era when what is called the -lias was formed, a fossiliferous stratum belonging to the secondary or -mesozoic rocks. They are not found in the later or tertiary rocks, and -thereon an argument might be deduced against their possible existence -in the present, or post-tertiary, period; but, as will presently be -shown, this argument is far from being conclusive. The enaliosaurian -reptiles were “extraordinary,” says Lyell, “for their number, size, and -structure.” Like the ichthyosauri, or fish-lizards, the enaliosauri -(or serpent-turtles, as they might almost be called) were carnivorous, -their skeletons often enclosing the fossilized remains of half-digested -fishes. They had extremely long necks, with heads very small compared -with the body. They are supposed to have lived chiefly in narrow seas -and estuaries, and to have breathed air like the modern whales and -other aquatic mammals. Some of them were of formidable dimensions, -though none of the skeletons yet discovered indicate a length of more -than 35 feet. It is not, however, at all likely that the few skeletons -known indicate the full size attained by these creatures. Probably, -indeed, we have the remains of only a few out of many species, and -some species existing in the mesozoic period may have as largely -exceeded those whose skeletons have been found, as the boa-constrictor -exceeds the common ringed snake. It is also altogether probable that -in the struggle for existence during which the enaliosaurian reptiles -have become _almost_ extinct (according to the hypothesis we are -considering), none but the largest and strongest had any chance, in -which case the present representatives of the family would largely -exceed in bulk their progenitors of the mesozoic period. - -A writer in the _Times_ of November 2, 1848, under the signature -F. G. S., pointed out how many of the external characters of the -creature seen from the _Dædalus_ corresponded with the belief that it -was a long-necked plesiosaurus. “Geologists,” he said, “are agreed in -the inference that the plesiosauri carried their necks, which must -have resembled the bodies of serpents, above the water, while their -propulsion was effected by large paddles working beneath, the short but -stout tail acting the part of a rudder.... In the letter and drawing -of Captain M’Quhæ ... we have ... the short head, the serpent-like -neck, carried several feet above the water. Even the bristly mane in -certain parts of the back, so unlike anything found in serpents, has -its analogue in the iguana, to which animal the plesiosaurus has been -compared by some geologists. But I would most of all insist upon the -peculiarity of the animal’s progression, which could only have been -effected with the evenness and at the rate described by an apparatus of -fins or paddles, not possessed by serpents, but existing in the highest -perfection in the plesiosaurus.” - -At this stage a very eminent naturalist entered the field—Professor -Owen. He dwelt first on a certain characteristic of Captain M’Quhæ’s -letter which no student of science could fail to notice—the definite -statement that the creature _was_ so and so, where a scientific -observer would simply have said that the creature presented such and -such characteristics. “No sooner was the captain’s attention called to -the object,” says Professor Owen, “than ‘it was discovered to be an -enormous serpent,’” though in reality the true nature of the creature -could not be determined even from the observations made during the -whole time that it remained visible. Taking, however, “the more certain -characters,” the “head with a convex, moderately capacious cranium, -short, obtuse muzzle, gape not extending further than to beneath the -eye, which (the eye) is rather small, round, filling closely the -palpebral aperture” (that is, the eyelids fit closely[25]); “colour and -surface as stated; nostrils indicated in the drawing by a crescentic -mark at the end of the nose or muzzle. All these,” proceeds Owen, -“are the characters of the head of a warm-blooded mammal, none of -them those of a cold-blooded reptile or fish. Body long, dark brown, -not undulating, without dorsal or other apparent fins, ‘but something -like the mane of a horse, or rather a bunch of sea-weed, washed about -its back.’” He infers that the creature had hair, showing only where -longest on the back, and therefore that the animal was not a mammal -of the whale species but rather a great seal. He then shows that the -sea-elephant, or _Phoca proboscidea_, which attains the length of -from 20 to 30 feet, was the most probable member of the seal family -to be found about 300 miles from the western shore of the southern -end of Africa, in latitude 24° 44´. Such a creature, accidentally -carried from its natural domain by a floating iceberg, would have -(after its iceberg had melted) to urge its way steadily southwards, -as the supposed sea-serpent was doing; and probably the creature -approached the _Dædalus_ to scan her “capabilities as a resting-place, -as it paddled its long, stiff body past the ship.” “In so doing it -would raise a head of the form and colour described and delineated -by Captain M’Quhæ”—its head only, be it remarked, corresponding -with the captain’s description. The neck also would be of the right -diameter. The thick neck, passing into an inflexible trunk, the longer -and coarser hair on the upper part of which would give rise to the -idea “explained by the similes above cited” (of a mane or bunch of -sea-weed), the paddles would be out of sight; and the long eddy and -wake created by the propelling action of the tail would account for the -idea of a long serpentine body, at least for this idea occurring to one -“looking at the strange phenomenon with a sea-serpent in his mind’s -eye.” “It is very probable that not one on board the _Dædalus_ ever -before beheld a gigantic seal freely swimming in the open ocean.” The -excitement produced by the strange spectacle, and the recollection of -“old Pontoppidan’s sea-serpent with the mane,” would suffice, Professor -Owen considered, to account for the metamorphosis of a sea-elephant -into a maned sea-serpent. - -This was not the whole of Professor Owen’s argument; but it may be well -to pause here, to consider the corrections immediately made by Captain -M’Quhæ; it may be noticed, first, that Professor Owen’s argument -seems sufficiently to dispose of the belief that the creature really -was a sea-serpent, or any cold-blooded reptile. And this view of the -matter has been confirmed by later observations. But few, I imagine, -can readily accept the belief that Captain M’Quhæ and his officers -had mistaken a sea-elephant for a creature such as they describe and -picture. To begin with, although it might be probable enough that -no one on board the _Dædalus_ had ever seen a gigantic seal freely -swimming in the open ocean—a sight which Professor Owen himself had -certainly never seen—yet we can hardly suppose they would not have -known a sea-elephant under such circumstances. Even if they had never -seen a sea-elephant at all, they would surely know what such an animal -is like. No one could mistake a sea-elephant for any other living -creature, even though his acquaintance with the animal were limited to -museum specimens or pictures in books. The supposition that the entire -animal, that is, its entire length, should be mistaken for 30 or 40 -feet of the length of a serpentine neck, seems, in my judgment, as -startling as the ingenious theory thrown out by some naturalists when -they first heard of the giraffe—to the effect that some one of lively -imagination had mistaken the entire body of a short-horned antelope for -the neck of a much larger animal! - -Captain M’Quhæ immediately replied:—“I assert that neither was it -a common seal nor a sea-elephant; its great length and its totally -different physiognomy precluding the possibility of its being a _Phoca_ -of any species. The head was flat, and not a capacious vaulted cranium; -nor had it a stiff, inflexible trunk—a conclusion to which Professor -Owen has jumped, most certainly not justified by my simple statement, -that ‘no portion of the 60 feet seen by us was used in propelling it -through the water, either by vertical or horizontal undulation.’” -He explained that the calculation of the creature’s length was made -before, not after, the idea had been entertained that the animal was -a serpent, and that he and his officers were “too well accustomed -to judge of lengths and breadths of objects in the sea to mistake a -real substance and an actual living body, coolly and dispassionately -contemplated, at so short a distance too, for the ‘eddy caused by -the action of the deeply immersed fins and tail of a rapidly moving, -gigantic seal raising its head above the water,’ as Professor Owen -imagines, in quest of its lost iceberg.” He next disposed of Owen’s -assertion that the idea of clothing the serpent with a mane had been -suggested by old Pontoppidan’s story, simply because he had never seen -Pontoppidan’s account or heard of Pontoppidan’s sea-serpent, until -he had told his own tale in London. Finally, he added, “I deny the -existence of excitement, or the possibility of optical illusion. I -adhere to the statement as to form, colour, and dimensions, contained -in my report to the Admiralty.” - -A narrative which appeared in the _Times_ early in 1849 must be -referred to in this place, as not being readily explicable by Professor -Owen’s hypothesis. It was written by Mr. R. Davidson, superintending -surgeon, Najpore Subsidiary Force Kamptee, and was to the following -effect (I abridge it considerably):—When at a considerable distance -south-west of the Cape of Good Hope, Mr. Davidson, Captain Petrie, of -the _Royal Saxon_, a steerage passenger, and the man at the wheel, saw -“an animal of which no more correct description could be given than -that by Captain M’Quhæ. It passed within 35 yards of the ship, without -altering its course in the least; but as it came right abreast of us it -slowly turned its head towards us.” About one-third of the upper part -of its body was above water, “in nearly its whole length; and we could -see the water curling up on its breast as it moved along, but by what -means it moved we could not perceive.” They _saw this creature in its -whole length_ with the exception of a small portion of the tail which -was under water; and by comparing its length with that of the _Royal -Saxon_, 600 feet, when exactly alongside in passing, they calculated it -to be in length as well as in other dimensions greater than the animal -described by Captain M’Quhæ. - -In the year 1852 two statements were made, one by Captain Steele, 9th -Lancers, the other by one of the officers of the ship _Barham_ (India -merchantman), to the effect that an animal of a serpentine appearance -had been seen about 500 yards from that ship (in longitude 40° E. and -37° 16´ S., that is, east of the south-eastern corner of Africa). “We -saw him,” said the former, “about 16 or 20 feet out of the water, and -he _spouted_ a long way from his head”—that is, I suppose, he spouted -to some distance, not, as the words really imply, at a part of his neck -far removed from the head. “Down his back he had a crest like a cock’s -comb, and was going very slowly through the water, but left a wake of -about 50 or 60 feet, as if dragging a long body after him. The captain -put the ship off her course to run down to him, but as we approached -him he went down. His colour was green with light spots. He was seen by -every one on board.” The other witness gives a similar account, adding -that the creature kept moving his head up and down, and was surrounded -by hundreds of birds. “We at first thought it was a dead whale.... -When we were within 100 yards he slowly sank into the depths of the -sea; while we were at dinner he was seen again.” Mr. Alfred Newton, -the well-known naturalist, guarantees his personal acquaintance with -one of the recipients of the letters just quoted from. But such a -guarantee is, of course, no sufficient guarantee of the authenticity -of the narrative. Even if the narrative be accepted, the case seems a -very doubtful one. The birds form a suspicious element in the story. -Why should birds cluster around a living sea creature? It seems to -me probable that the sea-weed theory, presently to be noticed, gives -the best explanation of this case. Possibly some great aggregation of -sea-weed was there, in which were entangled divers objects desirable -to birds and to fishes. These last may have dragged the mass under -water when the ship approached, being perhaps more or less entangled -in it—and it floated up again afterwards. The spouting may have been -simply the play of water over the part mistaken for the head. - -The sea-weed theory of the sea-serpent was broached in February, 1849, -and supported by a narrative not unlike the last. When the British -ship _Brazilian_ was becalmed almost exactly in the spot where M’Quhæ -had seen his monster, Mr. Herriman, the commander, perceived something -right abeam, about half a mile to the westward, “stretched along the -water to the length of about 25 or 30 feet, and perceptibly moving from -the ship with a steady, sinuous motion. The head, which seemed to be -lifted several feet above the waters, had something resembling a mane, -running down to the floating portion, and within about 6 feet of the -tail it forked out into a sort of double fin.” Mr. Herriman, his first -mate, Mr. Long, and several of the passengers, after surveying the -object for some time, came to the unanimous conclusion that it must be -the sea-serpent seen by Captain M’Quhæ. “As the _Brazilian_ was making -no headway, Mr. Herriman, determining to bring all doubts to an issue, -had a boat lowered down, and taking two hands on board, together with -Mr. Boyd, of Peterhead, near Aberdeen, one of the passengers, who -acted as steersman under the direction of the captain, they approached -the monster, Captain Herriman standing on the bow of the boat, armed -with a harpoon to commence the onslaught. The combat, however, was -not attended with the danger which those on board apprehended; for -on coming close to the object it was found to be nothing more than -an immense piece of sea-weed, evidently detached from a coral reef -and drifting with the current, which sets constantly to the westward -in this latitude, and which, together with the swell left by the -subsidence of the gale, gave it the sinuous, snake-like motion.” - -A statement was published by Captain Harrington in the _Times_ of -February, 1858, to the effect that from his ship _Castilian_, then -distant ten miles from the north-east end of St. Helena, he and -his officers had seen a huge marine animal within 20 yards of the -ship; that it disappeared for about half a minute, and then made its -appearance in the same manner again, showing distinctly its neck and -head about 10 or 12 feet out of the water. “Its head was shaped like -a long nun-buoy,” proceeds Captain Harrington, “and I suppose the -diameter to have been 7 or 8 feet in the largest part, with a kind of -scroll, or tuft, of loose skin encircling it about 2 feet from the top; -the water was discoloured for several hundred feet from its head.... -From what we saw from the deck, we conclude that it must have been over -200 feet long. The boatswain and several of the crew who observed it -from the top-gallant forecastle,[26] (query, cross-trees?) state that -it was more than double the length of the ship, in which case it must -have been 500 feet. Be that as it may, I am convinced that it belonged -to the serpent tribe; it was of a dark colour about the head, and was -covered with several white spots.” - -This immediately called out a statement from Captain F. Smith, of -the ship _Pekin_, that on December 28, not far from the place where -the _Dædalus_ had encountered the supposed sea-serpent, he had seen, -at a distance of about half a mile, a creature which was declared by -all hands to be the great sea-serpent, but proved eventually to be a -piece of gigantic sea-weed. “I have no doubt,” he says, that the great -sea-serpent seen from the _Dædalus_ “was a piece of the same weed.” - -It will have been noticed that the sea-weed sea-serpents, seen by -Captain F. Smith and by Captain Herriman, were both at a distance -of half a mile, at which distance one can readily understand that a -piece of sea-weed might be mistaken for a living creature. This is -rather different from the case of the _Dædalus_ sea-serpent, which -passed so near that had it been a man of the captain’s acquaintance -he could have recognized that man’s features with the naked eye. The -case, too, of Captain Harrington’s sea-serpent, seen within 20 yards -of the _Castilian_, can hardly be compared to those cases in which -sea-weed, more than 800 yards from the ship, was mistaken for a living -animal. An officer of the _Dædalus_ thus disposed of Captain Smith’s -imputation:—“The object seen from the ship was beyond all question a -living animal, moving rapidly through the water against a cross sea, -and within five points of a fresh breeze, with such velocity that -the water was surging against its chest as it passed along at a rate -probably of ten miles per hour. Captain M’Quhæ’s first impulse was to -tack in pursuit, but he reflected that we could neither lay up for it -nor overhaul it in speed. There was nothing to be done, therefore, but -to observe it as accurately as we could with our glasses as it came up -under our lee quarter and passed away to windward, being at its nearest -position not more than 200 yards from us; _the eye, the mouth, the -nostril, the colour, and the form, all being most distinctly visible -to us_.... My impression was that it was rather of a lizard than a -serpentine character, as its movement was steady and uniform, _as if -propelled by fins_, not by any undulatory power.” - -But all the evidence heretofore obtained respecting the sea-serpent, -although regarded by many naturalists, Gosse, Newman, Wilson, and -others, as demonstrating the existence of some as yet unclassified -monster of the deep, seems altogether indecisive by comparison with -that which has recently been given by the captain, mates, and crew -of the ship _Pauline_. In this case, assuredly, we have not to deal -with a mass of sea-weed, the floating trunk of a tree, a sea-elephant -hastening to his home amid the icebergs, or with any of the other more -or less ingenious explanations of observations previously made. We have -either the case of an actual living animal, monstrous, fierce, and -carnivorous, or else the five men who deposed on oath to the stated -facts devised the story between them, and wilfully perjured themselves -for no conceivable purpose—that, too, not as men have been known to -perjure themselves under the belief that none could know of their -infamy, but with the certainty on the part of each that four others -(any one of whom might one day shame him and the rest by confessing) -knew the real facts of the case. - -The story of the _Pauline_ sea-serpent ran simply as follows, as -attested at the Liverpool police-court:—“We, the undersigned, captain, -officers, and crew of the bark _Pauline_, of London, do solemnly -and sincerely declare, that on July 8, 1875, in latitude 5° 13´ S., -longitude 35° W., we observed three large sperm whales, and one of -them was gripped round the body with two turns of what appeared to be -a huge serpent. The head and tail appeared to have a length beyond -the coils of about 30 feet, and its girth 8 or 9 feet. The serpent -whirled its victim round and round for about fifteen minutes, and then -suddenly dragged the whale to the bottom, head first.—George Drevat, -master; Horatio Thompson, chief mate; John H. Landells, second mate; -William Lewarn, steward; Owen Baker, A.B. Again on the 13th July a -similar serpent was seen about 200 yards off, shooting itself along the -surface, head and neck being out of the water several feet. This was -seen only by the captain and an ordinary seaman.—George Drevat. A few -moments afterwards it was seen elevated some 60 feet perpendicularly -in the air by the chief officer and two seamen, whose signatures are -affixed.—Horatio Thompson, Owen Baker, William Lewarn.” - -The usual length of the cachalot or sperm whale is about 70 feet, and -its girth about 50 feet. If we assign to the unfortunate whale which -was captured on this occasion, a length of only 50 feet, and a girth -of only 35 feet, we should still have for the entire length of the -supposed serpent about 100 feet. This can hardly exceed the truth, -since the three whales are called large sperm whales. With a length of -100 feet and a girth of about 9 feet, however, a serpent would have -no chance in an attempt to capture a sperm whale 50 feet long and 35 -feet in girth, for the simple reason that the whale would be a good -deal heavier than its opponent. In a contest in open sea, where one -animal seeks to capture another bodily, weight is all-important. We -can hardly suppose the whale could be so compassed by the coils of his -enemy as to be rendered powerless; in fact, the contest lasted fifteen -minutes, during the whole of which time the so-called serpent was -whirling its victim round, though more massive than itself, through -the water. On the whole, it seems reasonable to conclude—in fact, the -opinion is almost forced upon us—that besides the serpentine portion -of its bulk, which was revealed to view, the creature, thus whirling -round a large sperm whale, had a massive concealed body, provided with -propelling paddles of enormous power. _These_ were at work all the time -the struggle went on, enabling the creature to whirl round its enemy -easily, whereas a serpentine form, with two-thirds of its length, at -least, coiled close round another body, would have had no propulsive -power left, or very little, in the remaining 30 feet of its length, -including both the head and tail ends beyond the coils. Such a creature -as an enaliosaurus _could_ no doubt have done what a serpent of twice -the supposed length would have attempted in vain—viz., dragged down -into the depths of the sea the mighty bulk of a cachalot whale. - -When all the evidence is carefully weighed, we appear led to the -conclusion that at least one large marine animal exists which has not -as yet been classified among the known species of the present era. It -would appear that this animal has certainly a serpentine neck, and a -head small compared with its body, but large compared with the diameter -of the neck. It is probably an air-breather and warm-blooded, and -certainly carnivorous. Its propulsive power is great and apparently -independent of undulations of its body, wherefore it presumably -has powerful concealed paddles. All these circumstances correspond -with the belief that it is a modern representative of the long-neck -plesiosaurians of the great secondary or mesozoic era, a member of that -strange family of animals whose figure has been compared to that which -would be formed by drawing a serpent through the body of a sea-turtle. - -Against this view sundry objections have been raised, which must now be -briefly considered. - -In the first place, Professor Owen pointed out that the sea-saurians -of the secondary period have been replaced in the tertiary and present -seas by the whales and allied races. No whales are found in the -secondary strata, no saurians in the tertiary. “It seems to me less -probable,” he says, “that no part of the carcase of such reptiles -should have ever been discovered in a recent unfossilized state, than -that men should have been deceived by a cursory view of a partly -submerged and rapidly moving animal which might only be strange to -themselves. In other words, I regard the negative evidence from the -utter absence of any of the recent remains of great sea-serpents, -krakens, or enaliosauria, as stronger against their actual existence, -than the positive statements which have hitherto weighed with the -public mind in favour of their existence. A larger body of evidence -from eye-witnesses might be got together in proof of ghosts than of the -sea-serpent.” - -To this it has been replied that genera are now known to exist, as the -_Chimæra_, the long-necked river tortoise, and the iguana, which are -closely related to forms which existed in the secondary era, while no -traces have been found of them in any of the intermediate or tertiary -strata. The chimæra is a case precisely analogous to the supposed case -of the enaliosaurus, for the chimæra is but rarely seen, like the -supposed enaliosaurus, is found in the same and absent from the same -fossiliferous strata. Agassiz is quoted in the _Zoologist_, page 2395, -as saying that it would be in precise conformity with analogy that such -an animal as the enaliosaurus should exist in the American seas, as -he had found numerous instances in which the fossil forms of the Old -World were represented by living types in the New. In close conformity -with this opinion is a statement made by Captain the Hon. George Hope, -that when in the British ship _Fly_, in the Gulf of California, the -sea being perfectly calm and transparent, he saw at the bottom a large -marine animal, with the head and general figure of an alligator, but -the neck much longer, and with four large paddles instead of legs. -Here, then, unless this officer was altogether deceived, which seems -quite unlikely under the circumstances, was a veritable enaliosaurus, -though of a far smaller species, probably, than the creature mistaken -for a sea-serpent. - -As for the absence of remains, Mr. Darwin has pointed out that -the fossils we possess are but fragments accidentally preserved -by favouring circumstances in an almost total wreck. We have many -instances of existent creatures, even such as would have a far better -chance of floating after death, and so getting stranded where their -bones might be found, which have left no trace of their existence. A -whale possessing two dorsal fins was said to have been seen by Smaltz, -a Sicilian naturalist; but the statement was rejected, until a shoal -of these whales were seen by two eminent French zoologists, MM. Quoy -and Gaimard. No carcase, skeleton, or bone of this whale has ever -been discovered. For seventeen hours a ship, in which Mr. Gosse was -travelling to Jamaica, was surrounded by a species of whale never -before noticed—30 feet long, black above and white beneath, with -swimming paws white on the upper surface. Here, he says, was “a whale -of large size, occurring in great numbers in the North Atlantic, which -on no other occasion has fallen under scientific observation. The -toothless whale of Havre, a species actually inhabiting the British -Channel, is only known from a single specimen accidentally stranded on -the French coast; and another whale, also British, is known only from -a single specimen cast ashore on the Elgin roast, and there seen and -described by the naturalist Sowerby. - -Dr. Andrew Wilson, in an interesting paper, in which he maintains that -sea-serpent tales are not to be treated with derision, but are worthy -of serious consideration, “supported as they are by zoological science, -and in the actual details of the case by evidence as trustworthy in -many cases as that received in our courts of law,” expresses the -opinion that plesiosauri and ichthyosauri have been unnecessarily -disinterred to do duty for the sea-serpents. But he offers as an -alternative only the ribbon-fish; and though some of these may attain -enormous dimensions, yet we have seen that some of the accounts of -the supposed sea-serpent, and especially the latest narrative by the -captain and crew of the _Pauline_, cannot possibly be explained by any -creature so flat and relatively so feeble as the ribbon-fish. - -On the whole, it appears to me that a very strong case has been made -out for the enaliosaurian, or serpent-turtle, theory of the so-called -sea-serpent. - -One of the ribbon-fish mentioned by Dr. Wilson, which was captured, -and measured more than 60 feet in length, might however fairly take -its place among strange sea creatures. I scarcely know whether to add -to the number a monstrous animal like a tadpole, or even more perhaps -like a gigantic skate, 200 feet in length, said to have been seen in -the Malacca Straits by Captain Webster and Surgeon Anderson, of the -ship _Nestor_. Perhaps, indeed, this monster, mistaken in the first -instance for a shoal, but presently found to be travelling along at -the rate of about ten knots an hour, better deserves to be called -a strange sea creature even than any of those which have been dealt -with in the preceding pages. But the only account I have yet seen -of Captain Webster’s statement, and Mr. Anderson’s corroboration, -appeared in an American newspaper; and though the story is exceedingly -well authenticated if the newspaper account of the matter is true, it -would not be at all a new feature in American journalism if not only -the story itself, but all the alleged circumstances of its narration, -should in the long run prove to be pure invention. - - - - -_ON SOME MARVELS IN TELEGRAPHY._ - - -Within the last few years Electric Telegraphy has received some -developments which seem wonderful even by comparison with those other -wonders which had before been achieved by this method of communication. -In reality, all the marvels of electric telegraphy are involved, so -to speak, in the great marvel of electricity itself, a phenomenon -as yet utterly beyond the interpretation of physicists, though not -more so than its fellow marvels, light and heat. We may, indeed, -draw a comparison between some of the most wonderful results which -have recently been achieved by the study of heat and light and those -effected in the application of electricity to telegraphy. It is as -startling to those unfamiliar with the characteristics of light, or -rather with certain peculiarities resulting from these characteristics, -to be told that an astronomer can tell whether there is water in the -air of Mars or Venus, or iron vapour in the atmosphere of Aldebaran -or Betelgeux, as it is to those unfamiliar with the characteristics -of electricity, or with the results obtained in consequence of these -characteristics, to be told that a written message can be copied by -telegraph, a map or diagram reproduced, or, most wonderful of all, -a musical air correctly repeated, or a verbal message made verbally -audible. Telegraphic marvels such as these bear to the original marvel -of mere telegraphic communication, somewhat the same relation which -the marvels of spectroscopic analysis as applied to the celestial orbs -bear to that older marvel, the telescopic scrutiny of those bodies. In -each case, also, there lies at the back of all these marvels a greater -marvel yet—electricity in the one case, light in the other. - -I propose in this essay to sketch the principles on which some of the -more recent wonders of telegraphic communication depend. I do not -intend to describe at any length the actual details or construction -of the various instruments employed. Precisely as the principles of -spectroscopic analysis can be made clear to the general reader without -the examination of the peculiarities of spectroscopic instruments, -so can the methods and principles of telegraphic communication be -understood without examining instrumental details. In fact, it may -be questioned whether general explanations are not in such cases -more useful than more detailed ones, seeing that these must of -necessity be insufficient for a student who requires to know the -subject practically in all its details, while they deter the general -reader by technicalities in which he cannot be expected to take any -interest. If it be asked, whether I myself, who undertake to explain -the principles of certain methods of telegraphic communication, have -examined _practically_ the actual instrumental working of these -methods, I answer frankly that I have not done so. As some sort -of proof, however, that without such practical familiarity with -working details the principles of the construction of instruments -may be thoroughly understood, I may remind the reader (see p. 96) -that the first spectroscopic battery I ever looked through—one in -which the dispersive power before obtained in such instruments had -been practically doubled—was of my own invention, constructed (with -a slight mechanical modification) by Mr. Browning, and applied at -once successfully to the study of the sun by Mr. Huggins, in whose -observatory I saw through this instrument the solar spectrum extended -to a length which, could it all have been seen at once, would have -equalled many feet.[27] On the other hand, it is possible to have a -considerable practical experience of scientific instruments without -sound knowledge of the principles of their construction; insomuch that -instances have been known in which men who have effected important -discoveries by the use of some scientific instrument, have afterwards -obtained their first clear conception of the principles of its -construction from a popular description. - -It may be well to consider, though briefly, some of the methods of -communication which were employed before the electric telegraph was -invented. Some of the methods of electric telegraphy have their -antitypes, so to speak, in methods of telegraphy used ages before the -application of electricity. The earliest employment of telegraphy -was probably in signalling the approach of invading armies by beacon -fires. The use of this method must have been well known in the time -of Jeremiah, since he warns the Benjamites “to set up a sign of fire -in Beth-haccerem,” because “evil appeareth out of the north and great -destruction.” Later, instead of the simple beacon fire, combinations -were used. Thus, by an Act of the Scottish Parliament in 1455, the -blazing of one bale indicated the probable approach of the English, two -bales that they were coming indeed, and four bales blazing beside each -other that they were in great force. The smoke of beacon fires served -as signals by day, but not so effectively, except under very favourable -atmospheric conditions. - -Torches held in the hand, waved, depressed, and so forth, were -anciently used in military signalling at night; while in the day-time -boards of various figures in different positions indicated either -different messages or different letters, as might be pre-arranged. - -Hooke communicated to the Royal Society in 1684 a paper describing a -method of “communicating one’s mind at great distances.” The letters -were represented by various combinations of straight lines, which might -be agreed upon previously if secrecy were desired, otherwise the same -forms might represent constantly the same letters. With four straight -planks any letter of this alphabet could be formed as wanted, and being -then run out on a framework (resembling a gallows in Hooke’s picture), -could be seen from a distant station. Two curved beams, combined in -various ways, served for arbitrary signals. - -Chappe, in 1793, devised an improvement on this in what was called -the T telegraph. An upright post supported a cross-bar (the top of -the T), at each end of which were the short dependent beams, making -the figure a complete Roman capital T. The horizontal bar as first -used could be worked by ropes within the telegraph-house, so as to be -inclined either to right or left. It thus had three positions. Each -dependent beam could be worked (also from within the house) so as to -turn upwards, horizontally, or downwards (regarding the top bar of -the T as horizontal), thus having also three positions. It is easily -seen that, since each position of one short beam could be combined -with each position of the other, the two together would present -three times three arrangements, or nine in all; and as these nine -could be given with the cross-bar in any one of its three positions, -there were in all twenty-seven possible positions. M. Chappe used an -alphabet of only sixteen letters, so that all messages could readily -be communicated by this telegraph. For shorter distances, indeed, and -in all later uses of Chappe’s telegraph, the short beams could be -used in intermediate positions, by which 256 different signals could -be formed. Such telegraphs were employed on a line beginning at the -Louvre and proceeding by Montmartre to Lisle, by which communications -were conveyed from the Committee of Public Welfare to the armies in the -Low Countries. Telescopes were used at each station. Barrère stated, -in an address to the Convention on August 17, 1794, that the news of -the recapture of Lisle had been sent by this line of communication to -Paris in one hour after the French troops had entered that city. Thus -the message was conveyed at the rate of more than 120 miles per hour. - -Various other devices were suggested and employed during the first half -of the present century. The semaphores still used in railway signalling -illustrate the general form which most of these methods assumed. An -upright, with two arms, each capable of assuming six distinct positions -(excluding the upright position), would give forty-eight different -signals; thus each would give six signals alone, or twelve for the -pair, and each of the six signals of one combined with each of the six -signals of the other, would give thirty-six signals, making forty-eight -in all. This number suffices to express the letters of the alphabet -(twenty-five only are needed), the Arabic numerals, and thirteen -arbitrary signals. - -The progress of improvement in such methods of signalling promised to -be rapid, before the invention of the electric telegraph, or rather, -before it was shown how the principle of the electric telegraph could -be put practically into operation. We have seen that they were capable -of transmitting messages with considerable rapidity, more than twice -as fast as we could now send a written message by express train. But -they were rough and imperfect. They were all, also, exposed to one -serious defect. In thick weather they became useless. Sometimes, at the -very time when it was most important that messages should be quickly -transmitted, fog interrupted the signalling. Sir J. Barrow relates that -during the Peninsular War grave anxiety was occasioned for several -hours by the interruption of a message from Plymouth, really intended -to convey news of a victory. The words transmitted were, “Wellington -defeated;” the message of which these words formed the beginning was: -“Wellington defeated the French at,” etc. As Barrow remarks, if the -message had run, “French defeated at,” etc., the interruption of the -message would have been of less consequence. - -Although the employment of electricity as a means of communicating -at a distance was suggested before the end of the last century, in -fact, so far back as 1774, the idea has only been worked out during -the last forty-two years. It is curious indeed to note that until -the middle of the present century the word “telegraph,” which is now -always understood as equivalent to electric telegraph, unless the -contrary is expressed, was commonly understood to refer to semaphore -signalling,[28] unless the word “electric” were added. - -The general principle underlying all systems of telegraphic -communication by electricity is very commonly misunderstood. The idea -seems to prevail that electricity can be sent out along a wire to any -place where some suitable arrangement has been made to receive it. In -one sense this is correct. But the fact that the electricity has to -make a circuit, returning to the place from which it is transmitted, -seems not generally understood. Yet, unless this is understood, the -principle, even the possibility, of electric communication is not -recognized. - -Let us, at the outset, clearly understand the nature of electric -communication. - -In a variety of ways, a certain property called electricity can be -excited in all bodies, but more readily in some than in others. This -property presents itself in two forms, which are called positive -and negative electricity, words which we may conveniently use, but -which must not be regarded as representing any real knowledge of -the distinction between these two kinds of electricity. In fact, -let it be remembered throughout, that we do not in the least know -what electricity is; we only know certain of the phenomena which -it produces. Any body which has become charged with electricity, -either positive or negative, will part with its charge to bodies in a -neutral condition, or charged with the opposite electricity (negative -or positive). But the transference is made much more readily to -some substances than to others—so slowly, indeed, to some, that in -ordinary experiments the transference may be regarded as not taking -place at all. Substances of the former kind are called good conductors -of electricity; those which receive the transfer of electricity less -readily are said to be bad conductors; and those which scarcely receive -it at all are called insulating substances. The reader must not -confound the quality I am here speaking of with readiness to become -charged with electricity. On the contrary, the bodies which most -freely receive and transmit electricity are least readily charged with -electricity, while insulating substances are readily electrified. Glass -is an insulator, but if glass is briskly rubbed with silk it becomes -charged (or rather, the part rubbed becomes charged) with positive -electricity, formerly called _vitreous_ electricity for this reason; -and again, if wax or resin, which are both good insulators, be rubbed -with cloth or flannel, the part rubbed becomes charged with negative, -formerly called _resinous_, electricity. - -Electricity, then, positive or negative, however generated, passes -freely along conducting substances, but is stopped by an insulating -body, just as light passes through transparent substances, but is -stopped by an opaque body. Moreover, electricity may be made to pass -to any distance along conducting bodies suitably insulated. Thus, it -might seem that we have here the problem of distant communication -solved. In fact, the first suggestion of the use of electricity in -telegraphy was based on this property. When a charge of electricity has -been obtained by the use of an ordinary electrical machine, this charge -can be drawn off at a distant point, if a conducting channel properly -insulated connects that point with the bodies (of whatever nature) -which have been charged with electricity. In 1747, Dr. Watson exhibited -electrical effects from the discharges of Leyden jars (vessels -suitably constructed to receive and retain electricity) at a distance -of two miles from the electrical machine. In 1774, Le Sage proposed -that by means of wires the electricity developed by an electrical -machine should be transmitted by insulated wires to a point where an -electroscope, or instrument for indicating the presence of electricity, -should, by its movements, mark the letters of the alphabet, one wire -being provided for each letter. In 1798 Béthencourt repeated Watson’s -experiment, increasing the distance to twenty-seven miles, the -extremities of his line of communication being at Madrid and Aranjuez. -(Guillemin, by the way, in his “Applications of the Physical Forces,” -passes over Watson’s experiment; in fact, throughout his chapters on -the electric telegraph, the steam-engine, and other subjects, he seems -desirous of conveying as far as possible the impression that all the -great advances of modern science had their origin in Paris and its -neighbourhood.) - -From Watson’s time until 1823 attempts were made in this country -and on the Continent to make the electrical machine serve as the -means of telegraphic communication. All the familiar phenomena of -the lecture-room have been suggested as signals. The motion of pith -balls, the electric spark, the perforation of paper by the spark, the -discharge of sparks on a fulminating pane (a glass sheet on which -pieces of tinfoil are suitably arranged, so that sparks passing from -one to another form various figures or devices), and other phenomena, -were proposed and employed experimentally. But practically these -methods were not effectual. The familiar phenomenon of the electric -spark explains the cause of failure. The spark indicates the passage of -electricity across an insulating medium—dry air—when a good conductor -approaches within a certain distance of the charged body. The greater -the charge of electricity, the greater is the distance over which the -electricity will thus make its escape. Insulation, then, for many miles -of wire, and still more for a complete system of communication such -as we now have, was hopeless, so long as frictional electricity was -employed, or considerable electrical intensity required. - -We have now to consider how galvanic electricity, discovered in 1790, -was rendered available for telegraphic communication. In the first -place, let us consider what galvanic or voltaic electricity is. - -I have said that electricity can be generated in many ways. It may -be said, indeed, that every change in the condition of a substance, -whether from mechanical causes, as, for instance, a blow, a series of -small blows, friction, and so forth, or from change of temperature, -moisture, and the like, or from the action of light, or from chemical -processes, results in the development of more or less electricity. - -When a plate of metal is placed in a vessel containing some acid -(diluted) which acts chemically on the metal, this action generates -negative electricity, which passes away as it is generated. But if a -plate of a different metal, either not chemically affected by the acid -or less affected than the former, be placed in the dilute acid, the two -plates being only partially immersed and not in contact, then, when a -wire is carried from one plate to the other, the excess of positive -electricity in the plate least affected by the acid is conveyed to -the other, or, in effect, discharged; the chemical action, however, -continues, or rather is markedly increased, fresh electricity is -generated, and the excess of positive electricity in the plate least -affected is constantly discharged. Thus, along the wire connecting -the two metals a current of electricity passes from the metal least -affected to the metal most affected; a current of negative electricity -passes in a contrary direction in the dilute acid. - -I have spoken here of currents passing along the wire and in the acid, -and shall have occasion hereafter to speak of the plate of metal least -affected as the positive pole, this plate being regarded, in this -case, as a source whence a current of positive electricity flows along -the wire connection to the other plate, which is called the negative -pole. But I must remind the reader that this is only a convenient -way of expressing the fact that the wire assumes a certain condition -when it connects two such plates, and is capable of producing certain -effects. Whether in reality any process is taking place which can be -justly compared to the flow of a current one way or the other, or -whether a negative current flows along the circuit one way, while the -positive current flows the other way, are questions still unanswered. -We need not here enter into them, however. In fact, very little is -known about these points. Nor need we consider here the various ways in -which many pairs of plates such as I have described can be combined in -many vessels of dilute acid to strengthen the current. Let it simply -be noted that such a combination is called a battery; that when the -extreme plates of opposite kinds are connected by a wire, a current -of electricity passes along the wire from the extreme plate of that -metal which is least affected, forming the positive pole, to the other -extreme plate of that metal which is most affected and forms the -negative pole. The metals commonly employed are zinc and copper, the -former being the one most affected by the action of the dilute acid, -usually sulphuric acid. But it must here be mentioned that the chemical -process, affecting both metals, but one chiefly, would soon render a -battery of the kind described useless; wherefore arrangements are made -in various ways for maintaining the efficiency of the dilute acid and -of the metallic plates, especially the copper: for the action of the -acid on the zinc tends, otherwise, to form on the copper a deposit of -zinc. I need not describe the various arrangements for forming what are -called constant batteries, as Daniell’s, Grove’s, Bunsen’s, and others. -Let it be understood that, instead of a current which would rapidly -grow weaker and weaker, these batteries give a steady current for a -considerable time. Without this, as will presently be seen, telegraphic -communication would be impossible. - -We have, then, in a galvanic battery a steady source of electricity. -This electricity is of low intensity, incompetent to produce the more -striking phenomena of frictional electricity. Let us, however, consider -how it would operate at a distance. - -The current will pass along any length of conducting substance properly -insulated. Suppose, then, an insulated wire passes from the positive -pole of a battery at a station A to a station B, and thence back to the -negative pole at the station A. Then the current passes along it, and -this can be indicated at B by some action such as electricity of low -intensity can produce. If now the continuity of the wire be interrupted -close by the positive pole at A, the current ceases and the action is -no longer produced. The observer at B knows then that the continuity of -the wire has been interrupted; he has been, in fact, signalled to that -effect. - -But, as I have said, the electrical phenomena which can be produced by -the current along a wire connecting the positive and negative poles -of a galvanic battery are not striking. They do not afford effective -signals when the distance traversed is very great and the battery not -exceptionally strong. Thus, at first, galvanic electricity was not more -successful in practice than frictional electricity. - -It was not until the effect of the galvanic current on the magnetic -needle had been discovered that electricity became practically -available in telegraphy. - -Oersted discovered in 1820 that a magnetic needle poised horizontally -is deflected when the galvanic current passes above it (parallel to -the needle’s length) or below it. If the current passes above it, the -north end of the needle turns towards the east when the current travels -from north to south, but towards the west when the current travels from -south to north; on the other hand, if the current passes below the -needle, the north end turns towards the west when the current travels -from south to north, and towards the east when the current travels from -north to south. The deflection will be greater or less according to the -power of the current. It would be very slight indeed in the case of a -needle, however delicately poised, above or below which passed a wire -conveying a galvanic current from a distant station. But the effect can -be intensified, as follows:— - -[Illustration: FIG. 1.] - -Suppose _a b c d e f_ to be a part of the wire from A to B, passing -above a delicately poised magnetic needle N S, along _a b_ and then -below the needle along _c d_, and then above again along _e f_ and so -to the station B. Let a current traverse the wire in the direction -shown by the arrows. Then N, the north end of the needle, is deflected -towards the east by the current passing along _a b_. But it is also -deflected to the east by the current passing along _c d_; for this -produces a deflection the reverse of that which would be produced by a -current in the same direction above the needle—that is, in direction -_b a_, and therefore the same as that produced by the current along -_a b_. The current along _e f_ also, of course, produces a deflection -of the end N towards the east. All three parts, then, _a b_, _c d_, -_e f_, conspire to increase the deflection of the end N towards the -east. If the wire were twisted once again round N S, the deflection -would be further increased; and finally, if the wire be coiled in the -way shown in Fig. 1, but with a great number of coils, the deflection -of the north end towards the east, almost imperceptible without such -coils, will become sufficiently obvious. If the direction of the -current be changed, the end N will be correspondingly deflected towards -the west. - -The needle need not be suspended horizontally. If it hang vertically, -that is, turn freely on a horizontal axis, and the coil be carried -round it as above described, the deflection of the upper end will be to -the right or to the left, according to the direction of the current. -The needle actually seen, moreover, is not the one acted upon by the -current. This needle is inside the coil; the needle seen turns on the -same axis, which projects through the coil. - -If, then, the observer at the station B have a magnetic needle suitably -suspended, round which the wire from the battery at A has been coiled, -he can tell by the movement of the needle whether a current is passing -along the wire in one direction or in the other; while if the needle is -at rest he knows that no current is passing. - -[Illustration: FIG. 2.] - -[Illustration: FIG. 3.] - -Now suppose that P and N, Fig. 2, are the positive and negative poles -of a galvanic battery at A, and that a wire passes from P to the -station B, where it is coiled round a needle suspended vertically -at _n_, and thence passes to the negative pole N. Let the wire be -interrupted at _a b_ and also at _c d_. Then no current passes along -the wire, and the needle _n_ remains at rest in a vertical position. -Now suppose the points _a b_ connected by the wire _a b_, and at the -same moment the points _c d_ connected by the wire _c d_, then a -current flows along P _a b_ to B, as shown in Fig. 2, circuiting the -coil round the needle _n_ and returning by _d c_ to N. The upper end -of the needle is deflected to the right while this current continues -to flow; returning to rest when the connection is broken at _a b_ -and _c d_. Next, let _c b_ and _a d_ be simultaneously connected as -shown by the cross-lines in Fig. 3. (It will be understood that _a d_ -and _b c_ do not touch each other where they cross.) The current will -now flow from P along _a d_ to B, circuiting round the needle _n_ in -a contrary direction to that in which it flowed in the former case, -returning by _b c_ to N. The upper end of the needle is deflected then -to the left while the current continues to flow along this course. - -I need not here describe the mechanical devices by which the connection -at _a b_ and _c d_ can be instantly changed so that the current may -flow either along _a b_ and _d c_, as in Fig. 2, circuiting the needle -in one direction, or along _a d_ and _b c_, as in Fig. 3, circuiting -the needle in the other direction. As I said at the outset, this paper -is not intended to deal with details of construction, only to describe -the general principles of telegraphic communication, and especially -those points which have to be explained in order that recent inventions -may be understood. The reader will see that nothing can be easier than -so to arrange matters that, by turning a handle, either (1), _a b_ and -_c d_ may be connected, or, (2), _a d_ and _c b_, or, (3), both lines -of communication interrupted. The mechanism for effecting this is -called a _commutator_. - -Two points remain, however, to be explained: First, A must be a -receiving station as well as a transmitting station; secondly, the -wire connecting B with N, in Figs. 2 and 3, can be dispensed with, for -it is found that if at B the wire is carried down to a large metal -plate placed some depth underground, while the wire at _c_ is carried -down to another plate similarly buried underground, the circuit is -completed even better than along such a return wire as is shown in the -figures. The earth either acts the part of a return wire, or else, -by continually carrying off the electricity, allows the current to -flow continuously along the single wire. We may compare the current -carried along the complete wire circuit, to water circulating in a pipe -extending continuously from a reservoir to a distance and back again to -the reservoir. Water sucked up continuously at one end could be carried -through the pipe so long as it was continuously returned to the -reservoir at the other; but it could equally be carried through a pipe -extending from that reservoir to some place where it could communicate -with the open sea—the reservoir itself communicating with the open -sea—an arrangement corresponding to that by which the return wire is -dispensed with, and the current from the wire received into the earth. - -The discovery that the return wire may be dispensed with was made by -Steinheil in 1837. - -The actual arrangement, then, is in essentials that represented in Fig. -4. - -[Illustration: FIG. 4.] - -A and B are the two stations; P N is the battery at A, P´ N´ the -battery at B; P´ P´ are the positive poles, N´ N´, the negative poles. -At _n_ is the needle of station A, at _n´_ the needle of station B. -When the handle of the commutator is in its mean position—which is -supposed to be the case at station B—the points _b´ d´_ are connected -with each other, but neither with _a´_ nor _c´_; no current, then, -passes from B to A, but station B is in a condition to receive -messages. (If _b´_ and _d´_ were not connected, of course no messages -could be received, since the current from A would be stopped at -_b´_—which does not mean that it would pass round _n´_ to _b´_, but -that, the passage being stopped at _b´_, the current would not flow at -all.) When (the commutator at B being in its mean position, or _d´ b´_ -connected, and communication with _c´_ and _a´_ interrupted) the handle -of the commutator at A is turned from its mean position in _one_ -direction, _a_ and _b_ are connected, as are _c_ and _d_—as shown in -the figure—while the connection between _b_ and _d_ is broken. Thus -the current passes from P by _a_ and _b_, round the needle _n_; thence -to station B, round needle _n´_, and by _b´_ and _d´_, to the earth -plate G´; and so along the earth to G, and by _d c_, to the negative -pole N. The upper end of the needle of both stations is deflected to -the right by the passage of the current in this direction. When the -handle of the commutator at A is turned in the other direction, _b_ and -_c_ are connected, as also _a_ and _d_; the current from P passes along -_a d_ to the ground plate G, thence to G´, along _d´ b´_, round the -needle _n´_, back by the wire to the station A, where, after circuiting -the needle _n_ in the same direction as the needle _n´_, it travels by -_b_ and _c_ to the negative pole N. The upper end of the needle, at -both stations, is deflected to the left by the passage of the current -in this direction. - -It is easily seen that, with two wires and one battery, two needles -can be worked at both stations, either one moving alone, or the other -alone, or both together; but for the two to move differently, two -batteries must be used. The systems by which either the movements of -a single needle, or of a pair of needles, may be made to indicate the -various letters of the alphabet, numerals, and so on, need not here be -described. They are of course altogether arbitrary, except only that -the more frequent occurrence of certain letters, as _e_, _t_, _a_, -renders it desirable that these should be represented by the simplest -symbols (as by a single deflection to right or left), while letters -which occur seldom may require several deflections. - -One of the inventions to which the title of this paper relates can now -be understood. - -[Illustration: FIG. 5.] - -In the arrangement described, when a message is transmitted, the -needle of the sender vibrates synchronously with the needle at the -station to which the message is sent. Therefore, till that message is -finished, none can be received at the transmitting station. In what -is called duplex telegraphy, this state of things is altered, the -needle at the sending station being left unaffected by the transmitted -current, so as to be able to receive messages, and in self-recording -systems to record them. This is done by dividing the current from the -battery into two parts of equal efficiency, acting on the needle at -the transmitting station in contrary directions, so that this needle -remains unaffected, and ready to indicate signals from the distant -station. The principle of this arrangement is indicated in Fig. 5. Here -_a b n_ represents the main wire of communication with the distant -station, coiled round the needle of the transmitting station in one -direction; the dotted lines indicate a finer short wire, coiled round -the needle in a contrary direction. When a message is transmitted, -the current along the main wire tends to deflect the needle at _n_ in -one direction, while the current along the auxiliary wire tends to -deflect it in the other direction. If the thickness and length of the -short wire are such as to make these two tendencies equal, the needle -remains at rest, while a message is transmitted to the distant station -along the main wire. In this state of things, if a current is sent -from the distant station along the wire in the direction indicated by -the dotted arrow, this current also circuits the auxiliary wire, but -in the direction indicated by the arrows on the dotted curve, which -is the same direction in which it circuits the main wire. Thus the -needle is deflected, and a signal received. When the direction of the -chief current at the transmitting station is reversed, so also is -the direction of the artificial current, so that again the needle is -balanced. Similarly, if the direction of the current from the distant -station is reversed, so also is the direction in which this current -traverses the auxiliary wire, so that again both effects conspire to -deflect the needle. - -There is, however, another way in which an auxiliary wire may be made -to work. It may be so arranged that, when a message is transmitted, -the divided current flowing equally in opposite directions, the -instrument at the sending station is not affected; but that when the -operator at the distant station sends a current along the main wire, -this neutralizes the current coming towards him, which current had -before balanced the artificial current. The latter, being no longer -counterbalanced, deflects the needle; so that, in point of fact, by -this arrangement, the signal received at a station is produced by the -artificial current at that station, though of course the real cause of -the signal is the transmission of the neutralizing current from the -distant station. - -The great value of duplex telegraphy is manifest. Not only can -messages be sent simultaneously in both directions along the wire—a -circumstance which of itself would double the work which the wire is -capable of doing—but all loss of time in arranging about the order -of outward and homeward messages is prevented. The saving of time is -especially important on long lines, and in submarine telegraphy. It is -also here that the chief difficulties of duplex telegraphy have been -encountered. The chief current and the artificial current must exactly -balance each other. For this purpose the flow along each must be -equal. In passing through the long wire, the current has to encounter -a greater resistance than in traversing the short wire; to compensate -for this difference, the short wire must be much finer than the long -one. The longer the main wire, the more delicate is the task of -effecting an exact balance. But in the case of submarine wires, another -and a much more serious difficulty has to be overcome. A land wire -is well insulated. A submarine wire is separated by but a relatively -moderate thickness of gutta-percha from water, an excellent conductor, -communicating directly with the earth, and is, moreover, surrounded by -a protecting sheathing of iron wires, laid spirally round the core, -within which lies the copper conductor. Such a cable, as Faraday long -since showed, acts precisely as an enormous Leyden jar; or rather, -Faraday showed that such a cable, without the wire sheathing, would -act when submerged as a Leyden jar, the conducting wire acting as -the interior metallic coating of such a jar, the gutta-percha as the -glass of the jar (the insulating medium), and the water acting as the -exterior metallic coating. Wheatstone showed further that such a cable, -with a wire sheathing, would act as a Leyden jar, even though not -submerged, the metal sheathing taking the part of the exterior coating -of the jar. Now, regarding the cable thus as a condenser, we see that -the transmission of a current along it may in effect be compared with -the passage of a fluid along a pipe of considerable capacity, into -which and from which it is conveyed by pipes of small capacity. There -will be a retardation of the flow of water corresponding to the time -necessary to fill up the large part of the pipe; the water may indeed -begin to flow through as quickly as though there were no enlargement of -the bore of the pipe, but the full flow from the further end will be -delayed. Just so it is with a current transmitted through a submarine -cable. The current travels instantly (or with the velocity of freest -electrical transmission) along the entire line; but it does not attain -a sufficient intensity to be recognized for some time, nor its full -intensity till a still longer interval has elapsed. The more delicate -the means of recognizing its flow, the more quickly is the signal -received. The time intervals in question are not, indeed, very great. -With Thomson’s mirror galvanometer, in which the slightest motion of -the needle is indicated by a beam of light (reflected from a small -mirror moving with the needle), the Atlantic cable conveys its signal -from Valentia to Newfoundland in about one second, while with the less -sensitive galvanometer before used the time would be rather more than -two seconds. - -Now, in duplex telegraphy the artificial current must be equal to the -chief current in intensity all the time; so that, since in submarine -telegraphy the current rises gradually to its full strength and as -gradually subsides, the artificial current must do the same. Reverting -to the illustration derived from the flow of water, if we had a small -pipe the rapid flow through which was to carry as much water one way as -the slow flow through a large pipe was to carry water the other way, -then if the large pipe had a widening along one part of its long course -the short pipe would require to have a similar widening along the -corresponding part of its short course. And to make the illustration -perfect, the widenings along the large pipe should be unequal in -different parts of the pipe’s length; for the capacity of a submarine -cable, regarded as a condenser, is different along different parts of -its length. What is wanted, then, for a satisfactory system of duplex -telegraphy in the case of submarine cables, is an artificial circuit -which shall not only correspond as a whole to the long circuit, but -shall reproduce at the corresponding parts of its own length all the -varieties of capacity existing along various parts of the length of the -submarine cable. - -Several attempts have been made by electricians to accomplish this -result. Let it be noticed that two points have to be considered: the -intensity of the current’s action, which depends on the resistance -it has to overcome in traversing the circuit; and the velocity of -transmission, depending on the capacity of various parts of the circuit -to condense or collect electricity. Varley, Stearn, and others have -endeavoured by various combinations of condensers with resistance coils -to meet these two requisites. But the action of artificial circuits -thus arranged was not sufficiently uniform. Recently Mr. J. Muirhead, -jun., has met the difficulty in the following way (I follow partially -the account given in the _Times_ of February 3, 1877, which the reader -will now have no difficulty in understanding):—He has formed his -second circuit by sheets of paper prepared with paraffin, and having -upon one side a strip of tinfoil, wound to and fro to represent -resistance. Through this the artificial current is conducted. On the -other side is a sheet of tinfoil to represent the sheathing,[29] and -to correspond to the capacity of the wire. Each sheet of paper thus -prepared may be made to represent precisely a given length of cable, -having enough tinfoil on one side to furnish the resistance, and on the -other to furnish the capacity. A sufficient number of such sheets would -exactly represent the cable, and thus the artificial or non-signalling -part of the current would be precisely equivalent to the signalling -part, so far as its action on the needle at the transmitting station -was concerned. “The new plan was first tried on a working scale,” says -the _Times_, “on the line between Marseilles and Bona; but it has -since been brought into operation from Marseilles to Malta, from Suez -to Aden, and lastly, from Aden to Bombay. On a recent occasion when -there was a break-down upon the Indo-European line, the duplex system -rendered essential service, and maintained telegraphic communication -which would otherwise have been most seriously interfered with.” The -invention, we may well believe, “cannot fail to be highly profitable to -the proprietors of submarine cables,” or to bring about “before long a -material reduction in the cost of messages from places beyond the seas.” - - * * * * * - -The next marvel of telegraphy to be described is the transmission -of actual facsimiles of writings or drawings. So far as strict -sequence of subject-matter is concerned, I ought, perhaps, at this -point, to show how duplex telegraphy has been surpassed by a recent -invention, enabling three or four or more messages to be simultaneously -transmitted telegraphically. But it will be more convenient to consider -this wonderful advance after I have described the methods by which -facsimiles of handwriting, etc., are transmitted. - -Hitherto we have considered the action of the electric current -in deflecting a magnetic needle to right or left, a method of -communication leaving no trace of its transmission. We have now to -consider a method at once simpler in principle and affording means -whereby a permanent record can be left of each message transmitted. - -[Illustration: FIG. 6.] - -If the insulated wire is twisted in the form of a helix or coil round -a bar of soft iron, the bar becomes magnetized while the current is -passing. If the bar be bent into the horse-shoe form, as in Fig. 6, -where A C B represents the bar, _a b c d e f_ the coil of insulated -wire, the bar acts as a magnet while the current is passing along the -coil, but ceases to do so as soon as the current is interrupted.[30] -If, then, we have a telegraphic wire from a distant station in electric -connection with the wire _a b c_, the part _e f_ descending to an -earth-plate, then, according as the operator at that distant station -transmits or stops the current, the iron A C B is magnetized or -demagnetized. The part C is commonly replaced by a flat piece of iron, -as is supposed to be the case with the temporary magnets shown in Fig. -7, where this flat piece is below the coils. - -So far back as 1838 this property was applied by Morse in America -in the recording instrument which bears his name, and is now (with -slight modifications) in general use not only in America but on the -Continent. The principle of this instrument is exceedingly simple. Its -essential parts are shown in Fig. 7; H is the handle, H _b_ the lever -of the manipulator at the station A. The manipulator is shown in the -position for receiving a message from the station B along the wire W. -The handle H´ of the manipulator at the station B is shown depressed, -making connection at _a´_ with the wire from the battery N´ P´. Thus a -current passes through the handle to _c´_, along the wire to _c_ and -through _b_ to the coil of the temporary magnet M, after circling which -it passes to the earth at _e_ and so by E´ to the negative pole N´. The -passage of this current magnetizes M, which draws down the armature -_m_. Thus the lever _l_, pulled down on this side, presses upwards the -pointed style _s_ against a strip of paper _p_ which is steadily rolled -off from the wheel W so long as a message is being received. (The -mechanism for this purpose is not indicated in Fig. 7.) Thus, so long -as the operator at B holds down the handle H´, the style _s_ marks the -moving strip of paper, the spring _r_, under the lever _s l_, drawing -the style away so soon as the current ceases to flow and the magnet to -act. If he simply depresses the handle for an instant, a dot is marked; -if longer, a dash; and by various combinations of dots and dashes all -the letters, numerals, etc., are indicated. When the operator at B has -completed his message, the handle H´ being raised by the spring under -it (to the position in which H is shown), a message can be received at -B. - -[Illustration: FIG. 7.] - -I have in the figure and description assumed that the current from -either station acts directly on the magnet which works the recording -style. Usually, in long-distance telegraphy, the current is too weak -for this, and the magnet on which it acts is used only to complete the -circuit of a local battery, the current from which does the real work -of magnetizing M at A or M´ at B, as the case may be. A local battery -thus employed is called a _relay_. - -The Morse instrument will serve to illustrate the _principle_ of the -methods by which facsimiles are obtained. The details of construction -are altogether different from those of the Morse instrument; they -also vary greatly in different instruments, and are too complex to be -conveniently described here. But the principle, which is the essential -point, can be readily understood. - -In working the Morse instrument, the operator at B depresses the handle -H´. Suppose that this handle is kept depressed by a spring, and that -a long strip of paper passing uniformly between the two points at _a_ -prevents contact. Then no current can pass. But if there is a hole in -this paper, then when the hole reaches _a_ the two metal points at _a_ -meet and the current passes. We have here the principle of the Bain -telegraph. A long strip of paper is punched with round and long holes, -corresponding to the dots and marks of a message by the Morse alphabet. -As it passes between a metal wheel and a spring, both forming part of -the circuit, it breaks the circuit until a hole allows the spring to -touch the wheel, either for a short or longer time-interval, during -which the current passes to the other station, where it sets a relay -at work. In Bain’s system the message is received on a chemically -prepared strip of paper, moving uniformly at the receiving station, and -connected with the negative pole of the relay battery. When contact is -made, the face of the paper is touched by a steel pointer connected -with the positive pole, and the current which passes from the end of -the pointer through the paper to the negative pole produces a blue -mark on the chemically prepared paper.[31] - -We see that by Bain’s arrangement a paper is marked with dots and -lines, corresponding to round and elongated holes, in a ribbon of -paper. It is only a step from this to the production of facsimiles of -writings or drawings. - -Suppose a sheet of paper so prepared as to be a conductor of -electricity, and that a message is written on the paper with some -non-conducting substance for ink. If that sheet were passed between -the knobs at _a_ (the handle H being pressed down by a spring), -whilst simultaneously a sheet of Bain’s chemically prepared paper -were passed athwart the steel pointer at the receiving station, -there would be traced across the last-named paper a blue line, which -would be broken at parts corresponding to those on the other paper -where the non-conducting ink interrupted the current. Suppose the -process repeated, each paper being slightly shifted so that the line -traced across either would be parallel and very close to the former, -but precisely corresponding as respects the position of its length. -Then this line, also, on the recording paper will be broken at parts -corresponding to those in which the line across the transmitting paper -meets the writing. If line after line be drawn in this way till the -entire breadth of the transmitting paper has been crossed by close -parallel lines, the entire breadth of the receiving paper will be -covered by closely marked blue lines except where the writing has -broken the contact. Thus a negative facsimile of the writing will -be found in the manner indicated in Figs. 8 and 9.[32] In reality, -in processes of this kind, the papers (unlike the ribbons on Bain’s -telegraph) are not carried across in the way I have imagined, but are -swept by successive strokes of a movable pointer, along which the -current flows; but the principle is the same. - -[Illustration: FIG. 8. FIG. 9.] - -It is essential, in such a process as I have described, first, that the -recording sheet should be carried athwart the pointer which conveys -the marking current (or the pointer carried across the recording -sheet) in precise accordance with the motion of the transmitting sheet -athwart the wire or style which conveys the current to the long wire -between the stations (or of this style across the transmitting sheet). -The recording sheet and the transmitting sheet must also be shifted -between each stroke by an equal amount. The latter point, is easily -secured; the former is secured by causing the mechanism which gives the -transmitting style its successive strokes to make and break circuit, -by which a temporary magnet at the receiving station is magnetized and -demagnetized; by the action of this magnet the recording pointer is -caused to start on its motion athwart the receiving sheet, and moving -uniformly it completes its thwart stroke at the same instant as the -transmitting style. - -Caselli’s pantelegraph admirably effects the transmission of -facsimiles. The transmitting style is carried by the motion of a -heavy pendulum in an arc of constant range over a cylindrical surface -on which the paper containing the message, writing, or picture, is -spread. As the swing of the pendulum begins, a similar pendulum at the -receiving station begins its swing; the same break of circuit which -(by demagnetizing a temporary magnet) releases one, releases the other -also. The latter swings in an arc of precisely the same range, and -carries a precisely similar style over a similar cylindrical surface -on which is placed the prepared receiving paper. In fact, the same -pendulum at either station is used for transmitting and for receiving -facsimiles. Nay, not only so, but each pendulum, as it swings, serves -in the work both of transmitting and recording facsimiles. As it -swings one way, it travels along a line over each of two messages or -drawings, while the other pendulum in its synchronous swing traces a -corresponding line over each of two receiving sheets; and as it swings -the other way, it traces a line on each of two receiving sheets, -corresponding to the lines along which the transmitting style of the -other is passing along two messages or drawings. Such, at least, is the -way in which the instrument works in busy times. It can, of course, -send a message, or two messages, without receiving any.[33] - -In Caselli’s pantelegraph matters are so arranged that instead of a -negative facsimile, like Fig. 9, a true facsimile is obtained in all -respects except that the letters and figures are made by closely set -dark lines instead of being dark throughout as in the message. The -transmitting paper is conducting and the ink non-conducting, as in -Bakewell’s original arrangement; but instead of the conducting paper -completing the circuit for the distant station, it completes a short -home circuit (so to speak) along which the current travels without -entering on the distant circuit When the non-conducting ink breaks the -short circuit, the current travels in the long circuit through the -recording pointer at the receiving station; and a mark is thus made -corresponding to the inked part of the transmitting sheet instead of -the blank part, as in the older plan. - -The following passage from Guillemin’s “Application of the Physical -Forces” indicates the effectiveness of Caselli’s pantelegraph not -only as respects the character of the message it conveys, but as -to rapidity of transmission. (I alter the measures from the metric -to our usual system of notation.[34]) “Nothing is simpler than the -writing of the pantelegraph. The message when written is placed on -the surface of the transmitting cylinder. The clerk makes the warning -signals, and then sets the pendulum going. The transmission of the -message is accomplished automatically, without the clerk having any -work to do, and consequently without [his] being obliged to acquire -any special knowledge. Since two despatches may be sent at the same -time—and since shorthand may be used—the rapidity of transmission -may be considerable.” “The long pendulum of Caselli’s telegraph,” says -M. Quet, “generally performs about forty oscillations a minute, and -the styles trace forty broken lines, separated from each other by less -than the hundredth part of an inch. In one minute the lines described -by the style have ranged over a breadth of more than half an inch, -and in twenty minutes of nearly 10½ inches. As we can give the lines -a length of 4¼ inches, it follows that in twenty minutes Caselli’s -apparatus furnishes the facsimile of the writing or drawing traced on a -metallized plate 4¼ inches broad by 10½ inches long. For clearness of -reproduction, the original writing must be very legible and in large -characters.” “Since 1865 the line from Paris to Lyons and Marseilles -has been open to the public for the transmission of messages by this -truly marvellous system.” - -It will easily be seen that Caselli’s method is capable of many -important uses besides the transmission of facsimiles of handwriting. -For instance, by means of it a portrait of some person who is to be -identified—whether fraudulent absconder, or escaped prisoner or -lunatic, or wife who has eloped from her husband, or husband who has -deserted his wife, or missing child, and so on—can be sent in a few -minutes to a distant city where the missing person is likely to be. All -that is necessary is that from a photograph or other portrait an artist -employed for the purpose at the transmitting station should, in bold -and heavy lines, sketch the lineaments of the missing person on one -of the prepared sheets, as in Fig. 10. The portrait at the receiving -station will appear as in Fig. 11, and if necessary an artist at this -station can darken the lines or in other ways improve the picture -without altering the likeness. - -[Illustration: FIG. 10. FIG. 11.] - -But now we must turn to the greatest marvel of all—the transmission of -tones, tunes, and words by the electric wire. - -The transmission of the rhythm of an air is of course a very simple -matter. I have seen the following passage from “Lardner’s Museum of -Science and Art,” 1859, quoted as describing an anticipation of the -telephone, though in reality it only shows what every one who has -heard a telegraphic indicator at work must have noticed, that the -click of the instrument may be made to keep time with an air. “We -were in the Hanover Street Office, when there was a pause in the -business operations. Mr. M. Porter, of the office at Boston—the -writer being at New York—asked what tune we would have? We replied, -‘Yankee Doodle,’ and to our surprise he immediately complied with our -request. The instrument, a Morse one, commenced drumming the notes of -the tune as perfectly and distinctly as a skilful drummer could have -made them at the head of a regiment, and many will be astonished to -hear that ‘Yankee Doodle’ can travel by lightning.... So perfectly -and distinctly were the sounds of the tunes transmitted, that good -instrumental performers could have no difficulty in keeping time with -the instruments at this end of the wires.... That a pianist in London -should execute a fantasia at Paris, Brussels, Berlin, and Vienna, at -the same moment, and with the same spirit, expression, and precision as -if the instruments at these distant places were under his fingers, is -not only within the limits of practicability, but really presents no -other difficulty than may arise from the expense of the performances. -From what has just been stated, it is clear that the time of music -has been already transmitted, and the production of the sounds does -not offer any more difficulty than the printing of the letters of a -despatch.” Unfortunately, Lardner omitted to describe how this easy -task was to be achieved. - -Reuss first in 1861 showed how a sound can be transmitted. At the -sending station, according to his method, there is a box, into which, -through a pipe in the side, the note to be transmitted is sounded. The -box is open at the top, and across it, near the top, is stretched -a membrane which vibrates synchronously with the aerial vibrations -corresponding to the note. At the middle of the membrane, on its upper -surface, is a small disc of metal, connected by a thin strip of copper -with the positive pole of the battery at the transmitting station. The -disc also, when the machine is about to be put in use, lightly touches -a point on a metallic arm, along which (while this contact continues) -the electric current passes to the wire communicating with the distant -station. At that station the wire is carried in a coil round a straight -rod of soft iron suspended horizontally in such a way as to be free -to vibrate between two sounding-boards. After forming this coil, the -wire which conveys the current passes to the earth-plate and so home. -As already explained, while the current passes, the rod of iron is -magnetized, but the rod loses its magnetization when the current ceases. - -Now, when a note is sounded in the box at the transmitting station, the -membrane vibrates, and at each vibration the metal disc is separated -from the point which it lightly touches when at rest. Thus contact is -broken at regular intervals, corresponding to the rate of vibration -due to the note. Suppose, for instance, the note _C_ is sounded; then -there are 256 complete vibrations in a second, the electric current is -therefore interrupted and renewed, and the bar of soft iron magnetized -and demagnetized, 256 times in a second. Now, it had been discovered -by Page and Henry that when a bar of iron is rapidly magnetized -and demagnetized, it is put into vibrations synchronizing with the -interruptions of the current, and therefore emits a note of the same -tone as that which has been sounded into the transmitting box. - -Professor Heisler, in his “Lehrbuch der technischen Physik,” 1866, -wrote of Reuss’s telephone: “The instrument is still in its infancy; -however, by the use of batteries of proper strength, it already -transmits not only single musical tones, but even the most intricate -melodies, sung at one end of the line, to the other, situated at a -great distance, and makes them perceptible there with all desirable -distinctness.” Dr. Van der Weyde, of New York, states that, after -reading an account of Reuss’s telephone, he had two such instruments -constructed, and exhibited them at the meeting of the Polytechnic -Club of the American Institute. “The original sounds were produced at -the furthest extremity of the large building (the Cooper Institute), -totally out of hearing of the Association; and the receiving -instrument, standing on the table in the lecture-room, produced, with -a peculiar and rather nasal twang, the different tunes sung into the -box at the other end of the line; not powerfully, it is true, but very -distinctly and correctly. In the succeeding summer I improved the form -of the box, so as to produce a more powerful vibration of the membrane. -I also improved the receiving instrument by introducing several iron -wires into the coil, so as to produce a stronger vibration. I submitted -these, with some other improvements, to the meeting of the American -Association for the Advancement of Science, and on that occasion (now -seven years ago) expressed the opinion that the instrument contained -the germ of a new method of working the electric telegraph, and would -undoubtedly lead to further improvements in this branch of science.” - -The telephonic successes recently achieved by Mr. Gray were in -part anticipated by La Cour, of Copenhagen, whose method may be -thus described: At the transmitting station a tuning-fork is set -in vibration. At each vibration one of the prongs touches a fine -strip of metal completing a circuit. At the receiving station the -wire conveying the electric current is coiled round the prongs of -another tuning-fork of the same tone, but without touching them. -The intermittent current, corresponding as it does with the rate of -vibration proper to the receiving fork, sets this fork in vibration; -and in La Cour’s instrument the vibrations of the receiving fork -were used to complete the circuit of a local battery. His object was -not so much the production of tones as the use of the vibrations -corresponding to different tones, to act on different receiving -instruments. For only a fork corresponding to the sending fork could -be set in vibration by the intermittent current resulting from the -latter’s vibrations. So that, if there were several transmitting forks, -each could send its own message at the same time, each receiving fork -responding only to the vibrations of the corresponding transmitting -fork. La Cour proposed, in fact, that his instrument should be used -in combination with other methods of telegraphic communication. Thus, -since the transmitting fork, whenever put in vibration, sets the local -battery of the receiving station at work, it can be used to work a -Morse instrument, or it could work an ordinary Wheatstone and Cook -instrument, or it could be used for a pantelegraph. The same wire, when -different forks are used, could work simultaneously several instruments -at the receiving station. One special use indicated by La Cour was the -adaptation of his system to the Caselli pantelegraph, whereby, instead -of one style, a comb of styles might be carried over the transmitting -and recording plates. It would be necessary, in all such applications -of his method (though, strangely enough, La Cour’s description makes -no mention of the point), that the vibrations of the transmitting fork -should admit of being instantly stopped or “damped.” - -Mr. Gray’s system is more directly telephonic, as aiming rather at the -development of sound itself than at the transmission of messages by -the vibrations corresponding to sound. A series of tuning-forks are -used, which are set in separate vibration by fingering the notes of a -key-board. The vibrations are transmitted to a receiving instrument -consisting of a series of reeds, corresponding in note to the series of -transmitting forks, each reed being enclosed in a sounding-box. These -boxes vary in length from two feet to six inches, and are connected -by two wooden bars, one of which carries an electro-magnet, round the -coils of which pass the currents from the transmitting instrument. When -a tuning-fork is set in vibration by the performer at the transmitting -key-board, the electro-magnet is magnetized and demagnetized -synchronously with the vibrations of the fork. Not only are vibrations -thus imparted to the reed of corresponding note, but these are -synchronously strengthened by thuds resulting from the lengthening of -the iron when magnetized. - -So far as its musical capabilities are concerned, Gray’s telephone can -hardly be regarded as fulfilling all the hopes that have been expressed -concerning telephonic music. “Dreaming enthusiasts of a prophetic turn -of mind foretold,” we learn, “that a time would come when future Pattis -would sing on a London stage to audiences in New York, Berlin, St. -Petersburg, Shanghai, San Francisco, and Constantinople all at once.” -But the account of the first concert given at a distance scarcely -realizes these fond expectations. When “Home, Sweet Home,” played at -Philadelphia, came floating through the air at the Steinway Hall, New -York, “the sound was like that of a distant organ, rather faint, for a -hard storm was in progress, and there was consequently a great leakage -of the electric current, but quite clear and musical. The lower notes -were the best, the higher being sometimes almost inaudible. ‘The Last -Rose of Summer,’ ‘Com’ è gentil,’ and other melodies, followed, with -more or less success. There was no attempt to play chords,” though -three or four notes can be sounded together. It must be confessed that -the rosy predictions of M. Strakosch (the _impresario_) “as to the -future of this instrument seem rather exalted, and we are not likely as -yet to lay on our music from a central reservoir as we lay on gas and -water, though the experiment was certainly a very curious one.” - -The importance of Mr. Gray’s, as of La Cour’s inventions, depends, -however, far more on the way in which they increase the message-bearing -capacity of telegraphy than on their power of conveying airs to a -distance. At the Philadelphia Exhibition, Sir W. Thomson heard four -messages sounded simultaneously by the Gray telephone. The Morse -alphabet was used. I have mentioned that in that alphabet various -combinations of dots and dashes are used to represent different -letters; it is only necessary to substitute the short and long duration -of a note for dots and dashes to have a similar sound alphabet. -Suppose, now, four tuning-forks at the transmitting station, whose -notes are _Do_ [Illustration], _Mi_, _Sol_, and _Do_ [Illustration], -or say _C_, _E_, _G_, and _C_´, then by each of these forks a -separate message may be transmitted, all the messages being carried -simultaneously by the same line to separate sounding reeds (or forks, -if preferred), and received by different clerks. With a suitable -key-board, a single clerk could send the four messages simultaneously, -striking chords instead of single notes, though considerable practice -would be necessary to transform four verbal messages at once into the -proper telephonic music, and some skill in fingering to give the proper -duration to each note. - -Lastly, we come to the greatest achievement of all, Professor Graham -Bell’s vocal telephone. In the autumn of 1875 I had the pleasure -of hearing from Professor Bell in the course of a ride—all too -short—from Boston to Salem, Mass., an account of his instrument as -then devised, and of his hopes as to future developments. These hopes -have since been in great part fulfilled, but I venture to predict that -we do not yet know all, or nearly all, that the vocal telephone, in -Bell’s hands, is to achieve. - -It ought to be mentioned at the outset that Bell claims to have -demonstrated in 1873 (a year before La Cour) the possibility of -transmitting several messages simultaneously by means of the Morse -alphabet. - -Bell’s original arrangement for vocal telephony was as follows:—At one -station a drumhead of goldbeaters’ skin, about 2¾ inches in diameter, -was placed in front of an electro-magnet. To the middle of the -drumhead, on the side towards the magnet, was glued a circular piece -of clockspring. A similar electro-magnet, drumhead, etc., were placed -at the other station. When notes were sung or words spoken before one -drumhead, the vibrations of the goldbeaters’ skin carried the small -piece of clockspring vibratingly towards and from the electro-magnet, -without producing actual contact. Now, the current which was passing -along the coil round the electro-magnet changed in strength with each -change of position of this small piece of metal. The more rapid the -vibrations, and the greater their amplitude, the more rapid and the -more intense were the changes in the power of the electric current. -Thus, the electro-magnet at the other station underwent changes of -power which were synchronous with, and proportionate to, those changes -of power in the current which were produced by the changes of position -of the vibrating piece of clockspring. Accordingly, the piece of -clockspring at the receiving station, and with it the drumhead there, -was caused by the electro-magnet to vibrate with the same rapidity and -energy as the piece at the transmitting station. Therefore, as the -drumhead at one station varied its vibrations in response to the sounds -uttered in its neighbourhood, so the drumhead at the other station, -varying its vibrations, emitted similar sounds. Later, the receiving -drumhead was made unlike the transmitting one. Instead of a membrane -carrying a small piece of metal, a thin and very flexible disc of -sheet-iron, held in position by a screw, was used. This disc, set in -vibration by the varying action of an electro-magnet, as in the older -arrangement, uttered articulate sounds corresponding to those which, -setting in motion the membrane at the transmitting station, caused the -changes in the power of the electric current and in the action of the -electro-magnet. - -At the meeting of the British Association in 1876 Sir W. Thomson gave -the following account of the performance of this instrument at the -Philadelphia Exhibition:—“In the Canadian department” (for Professor -Bell was not at the time an American citizen) “I heard ‘To be or not -to be—there’s the rub,’ through the electric wire; but, scorning -monosyllables, the electric articulation rose to higher flights, and -gave me passages taken at random from the New York newspapers:—‘S. S. -Cox has arrived’ (I failed to make out the ‘S. S. Cox’), ‘the City -of New York,’ ‘Senator Morton,’ ‘the Senate has resolved to print a -thousand extra copies,’ ‘the Americans in London have resolved to -celebrate the coming Fourth of July.’ All this my own ears heard -spoken to me with unmistakable distinctness by the thin circular disc -armature of just such another little electro-magnet as this which I -hold in my hand. The words were shouted with a clear and loud voice -by my colleague judge, Professor Watson, at the far end of the line, -holding his mouth close to a stretched membrane, carrying a piece of -soft iron, which was thus made to perform in the neighbourhood of an -electro-magnet, in circuit with the line, motions proportional to the -sonorific motions of the air. This, the greatest by far of all the -marvels of the electric telegraph, is due to a young countryman of -our own, Mr. Graham Bell, of Edinburgh, and Montreal, and Boston, now -about to become a naturalized citizen of the United States. Who can -but admire the hardihood of invention which devised such very slight -means to realize the mathematical conception that, if electricity is -to convey all the delicacies of quality which distinguish articulate -speech, the strength of its current must vary continuously, and as -nearly as may be in simple proportion to the velocity of a particle of -air engaged in constituting the sound?” - -Since these words were spoken by one of the highest authorities in -matters telegraphic, Professor Bell has introduced some important -modifications in his apparatus. He now employs, not an electro-magnet, -but a permanent magnet. That is to say, instead of using at each -station such a bar of soft iron as is shown in Fig. 6, which becomes -a magnet while the electric current is passing through the coil -surrounding it, he uses at each station a bar of iron permanently -magnetized (or preferably a powerful magnet made of several horse-shoe -bars—that is, a compound magnet), surrounded similarly by coils of -wire. No battery is needed. Instead of a current through the coils -magnetizing the iron, the iron already magnetized causes a current -to traverse the coils whenever it acts, or rather whenever its action -changes. If an armature were placed across its ends or poles, at -the moment when it drew that armature to the poles by virtue of its -magnetic power, a current would traverse the coils; but afterwards, -so long as the armature remained there, there would be no current. If -an armature placed near the poles were shifted rapidly in front of -the poles, currents would traverse the coils, or be induced, their -intensity depending on the strength of the magnet, the length of the -coil, and the rapidity and range of the motions. In front of the -poles of the magnet is a diaphragm of very flexible iron (or else -some other flexible material bearing a small piece of iron on the -surface nearest the poles). A mouthpiece to converge the sound upon -this diaphragm substantially completes the apparatus at each station. -Professor Bell thus describes the operation of the instrument:—“The -motion of steel or iron in front of the poles of a magnet creates a -current of electricity in coils surrounding the poles of the magnet, -and the duration of this current of electricity coincides with the -duration of the motion of the steel or iron moved or vibrated in the -proximity of the magnet. When the human voice causes the diaphragm to -vibrate, electrical undulations are induced in the coils around the -magnets precisely similar to the undulations of the air produced by the -voice. The coils are connected with the line wire, and the undulations -induced in them travel through the wire, and, passing through the coils -of another instrument of similar construction at the other end of the -line, are again resolved into air undulations by the diaphragm of this -(other) instrument.” - -So perfectly are the sound undulations repeated—though the instrument -has not yet assumed its final form—that not only has the lightest -whisper uttered at one end of a line of 140 miles been distinctly heard -at the other, but the speaker can be distinguished by his voice when he -is known to the listener. So far as can be seen, there is every room -to believe that before long Professor Bell’s grand invention will be -perfected to such a degree that words uttered on the American side of -the Atlantic will be heard distinctly after traversing 2000 miles under -the Atlantic, at the European end of the submarine cable—so that Sir -W. Thomson at Valentia could tell by the voice whether Graham Bell, -or Cyrus Field, or his late colleague Professor Watson, were speaking -to him from Newfoundland. Yet a single wave of those which toss in -millions on the Atlantic, rolling in on the Irish strand, would utterly -drown the voices thus made audible after passing beneath two thousand -miles of ocean. - -Here surely is the greatest of telegraphic achievements. Of all the -marvels of telegraphy—and they are many—none are equal to, none -seem even comparable with, this one. Strange truly is the history of -the progress of research which has culminated in this noble triumph, -wonderful the thought that from the study of the convulsive twitchings -of a dead frog by Galvani, and of the quivering of delicately poised -magnetic needles by Ampère, should gradually have arisen through -successive developments a system of communication so perfect and so -wonderful as telegraphy has already become, and promising yet greater -marvels in the future. - -The last paragraph had barely been written when news arrived of another -form of telephone, surpassing Gray’s and La Cour’s in some respects as -a conveyor of musical tones, but as yet unable to speak like Bell’s. It -is the invention of Mr. Edison, an American electrician. He calls it -the motograph. He discovered about six years ago the curious property -on which the construction of the instrument depends. If a piece of -paper moistened with certain chemical solutions is laid upon a metallic -plate connected with the positive pole of a galvanic battery, and a -platinum wire connected with the negative pole is dragged over the -moistened paper, the wire slides over the paper like smooth iron over -ice—the usual friction disappearing so long as the current is passing -from the wire to the plate through the paper. At the receiving station -of Mr. Edison’s motograph there is a resonating box, from one face -of which extends a spring bearing a platinum point, which is pressed -by the spring upon a tape of chemically prepared paper. This tape is -steadily unwound, drawing by its friction the platinum point, and -with it the face of the resonator, outwards. This slight strain on -the face of the resonator continues so long as no current passes from -the platinum point to the metallic drum over which the moistened tape -is rolling. But so soon as a current passes, the friction immediately -ceases, and the face of the resonator resumes its normal position. If -then at the transmitting station there is a membrane or a very fine -diaphragm (as in Reuss’s or Bell’s arrangement) which is set vibrating -by a note of any given tone, the current, as in those arrangements, is -transmitted and stopped at intervals corresponding to the tone, and the -face of the resonating box is freed and pulled at the same intervals. -Hence, it speaks the corresponding tone. The instrument appears to have -the advantage over Gray’s in range. In telegraphic communication Gray’s -telephone is limited to about one octave. Edison’s extends from the -deepest bass notes to the highest notes of the human voice, which, when -magnets are employed, are almost inaudible. But Edison’s motograph has -yet to learn to speak. - -Other telegraphic marvels might well find a place here. I might speak -of the wonders of submarine telegraphy, and of the marvellous delicacy -of the arrangements by which messages by the Atlantic Cable are read, -and not only read, but made to record themselves. I might dwell, again, -on the ingenious printing telegraph of Mr. Hughes, which sets up its -own types, inks them, and prints them, or on the still more elaborate -plan of the Chevalier Bonelli “for converting the telegraph stations -into so many type-setting workshops.” But space would altogether -fail me to deal properly with these and kindred marvels. There is, -however, one application of telegraphy, especially interesting to the -astronomer, about which I must say a few words: I mean, the employment -of electricity as a regulator of time. Here again it is the principle -of the system, rather than details of construction, which I propose to -describe. Suppose we have a clock not only of excellent construction, -but under astronomical surveillance, so that when it is a second or so -in error it is set right again by the stars. Let the pendulum of this -clock beat seconds; and at each beat let a galvanic current be made and -broken. This may be done in many ways—thus the pendulum may at each -swing tilt up a very light metallic hammer, which forms part of the -circuit when down; or the end of the pendulum may be covered with some -non-conducting substance which comes at each swing between two metallic -springs in very light contact, separating them and so breaking circuit; -or in many other ways the circuit may be broken. When the circuit -is made, let the current travel along a wire which passes through a -number of stations near or remote, traversing at each the coils of a -temporary magnet. Then, at each swing of the pendulum of the regulating -clock, each magnet is magnetized and demagnetized. Thus each, once in -a second, draws to itself, and then releases its armature, which is -thereupon pulled back by a spring. Let the armature, when drawn to the -magnet, move a lever by which one tooth of a wheel is carried forward. -Then the wheel is turned at the rate of one tooth per second. This -wheel communicates motion to others in the usual way. In fact, we have -at each station a clock driven, _not_ by a weight or spring and with a -pendulum which allows one tooth of an escapement wheel to pass at each -swing, but by the distant regulating clock which turns a driving wheel -at the rate of one tooth per second, that is, one tooth for each swing -of the regulating clock’s pendulum. Each clock, then, keeps perfect -time with the regulating clock. In astronomy, where it is often of the -utmost importance to secure perfect synchronism of observation, or the -power of noting the exact difference of time between observations made -at distant stations, not only can the same clock thus keep time for -two observers hundreds of miles apart, but each observer can record by -the same arrangement the moment of the occurrence of some phenomenon. -For if a tape be unwound automatically, as in the Morse instrument, -it is easy so to arrange matters that every second’s beat of the -pendulum records itself by a dot or short line on the tape, and that -the observer can with a touch make (or break) contact at the instant of -observation, and so a mark be made properly placed between two seconds’ -marks—thus giving the precise time when the observation was made. Such -applications, however, though exceedingly interesting to astronomers, -are not among those in which the general public take chief interest. -There was one occasion, however, when astronomical time-relations were -connected in the most interesting manner with one of the greatest of -all the marvels of telegraphy: I mean, when the _Great Eastern_ in -mid-ocean was supplied regularly with Greenwich time, and this so -perfectly (and therefore with such perfect indication of her place in -the Atlantic), that when it was calculated from the time-signals that -the buoy left in open ocean to mark the place of the cut cable had been -reached, and the captain was coming on deck with several officers to -look for it, the buoy announced its presence by thumping the side of -the great ship. - - - - -_THE PHONOGRAPH, OR VOICE-RECORDER._ - - -In the preceding essay I have described the wonderful instrument called -the telephone, which has recently become as widely known in this -country as in America, the country of its first development. I propose -now briefly to describe another instrument—the phonograph—which, -though not a telegraphic instrument, is related in some degree to the -telephone. In passing, I may remark that some, who as telegraphic -specialists might be expected to know better, have described the -phonograph as a telegraphic invention. A writer in the _Telegraphic -Journal_, for instance, who had mistaken for mine a paper on the -phonograph in one of our daily newspapers, denounced me (as the -supposed author of that paper) for speaking of the possibility of -crystallizing sound by means of this instrument; and then went on to -speak of the mistake I (that is, said author) had made in leaving my -own proper subject of study to speak of telegraphic instruments and -to expatiate on the powers of electricity. In reality the phonograph -has no relation to telegraphy whatever, and its powers do not in the -slightest degree depend on electricity. If the case had been otherwise, -it may be questioned whether the student of astronomy, or of any other -department of science, should be considered incompetent of necessity -to describe a telegraphic instrument, or to discuss the principles -of telegraphic or electrical science. What should unquestionably be -left to the specialist, is the description of the practical effect of -details of instrumental construction, and the like—for only he who is -in the habit of using special instruments or classes of instrument can -be expected to be competent adequately to discuss such matters. - -Although, however, the phonograph is not an instrument depending, like -the telephone, on the action of electricity (in some form or other), -yet it is related closely enough to the telephone to make the mistake -of the _Telegraphic_ journalist a natural one. At least, the mistake -would be natural enough for any one but a telegraphic specialist; the -more so that Mr. Edison is a telegraphist, and that he has effected -several important and interesting inventions in telegraphic and -electrical science. For instance, in the previous article, pp. 270, -271, I had occasion to describe at some length the principles of his -“Motograph.” I spoke of it as “another form of telephone, surpassing -Gray’s and La Cour’s in some respects as a conveyer of musical -tones, but as yet unable to speak like Bell’s ... in telegraphic -communication.” I proceeded: “Gray’s telephone is limited to about one -octave. Edison’s extends from the deepest bass notes to the highest -notes of the human voice, which, when magnets are employed, are almost -inaudible; but it has yet to learn to speak.” - -The phonograph is an instrument which _has_ learned to speak, though -it does not speak at a distance like the telephone or the motograph. -Yet there seems no special reason why it should not combine both -qualities—the power of repeating messages at considerable intervals of -time after they were originally spoken, and the power of transmitting -them to great distances. - -I have said that the phonograph is an instrument closely related to the -telephone. If we consider this feature of the instrument attentively, -we shall be led to the clearer recognition of the acoustical principles -on which its properties depend, and also of the nature of some of the -interesting acoustical problems on which light seems likely to be -thrown by means of experiments with this instrument. - -In the telephone a stretched membrane, or a diaphragm of very flexible -iron, vibrates when words are uttered in its neighbourhood. When -a stretched membrane is used, with a small piece of iron at the -centre, this small piece of iron, as swayed by the vibrations of the -membrane, causes electrical undulations to be induced in the coils -round the poles of a magnet placed in front of the membrane. These -undulations travel along the wire and pass through the coils of another -instrument of similar construction at the other end of the wire, where, -accordingly, a stretched membrane vibrates precisely as the first had -done. The vibrations of this membrane excite atmospheric vibrations -identical in character with those which fell upon the first membrane -when the words were uttered in its neighbourhood; and therefore the -same words appear to be uttered in the neighbourhood of the second -membrane, however far it may be from the transmitting membrane, so only -that the electrical undulations are effectually transmitted from the -sending to the receiving instrument. - -I have here described what happened in the case of that earlier form -of the telephone in which a stretched membrane of some such substance -as goldbeater’s skin was employed, at the centre of which only was -placed a small piece of iron. For in its bearing on the subject of -the phonograph, this particular form of telephonic diaphragm is -more suggestive than the later form in which very flexible iron was -employed. We see that the vibrations of a small piece of iron at the -centre of a membrane are competent to reproduce all the peculiarities -of the atmospheric waves which fall upon the membrane when words are -uttered in its neighbourhood. This must be regarded, I conceive, as a -remarkable acoustical discovery. Most students of acoustics would have -surmised that to reproduce the motions merely of the central parts -of a stretched diaphragm would be altogether insufficient for the -reproduction of the complicated series of sound-waves corresponding to -the utterance of words. I apprehend that if the problem had originally -been suggested simply as an acoustical one, the idea entertained -would have been this—that though the motions of a diaphragm receiving -vocal sound-waves _might_ be generated artificially in such sort as to -produce the same vocal sounds, yet this could only be done by first -determining what particular points of the diaphragm were centres of -motion, so to speak, and then adopting some mechanical arrangements for -giving to small portions of the membrane at these points the necessary -oscillating motions. It would not, I think, have been supposed that -motions communicated to the centre of the diaphragm would suffice to -make the whole diaphragm vibrate properly in all its different parts. - -Let us briefly consider what was before known about the vibrations -of plates, discs, and diaphragms, when particular tones were sounded -in their neighbourhood; and also what was known respecting the -requirements for vocal sounds and speech as distinguished from simple -tones. I need hardly say that I propose only to consider these points -in a general, not in a special, manner. - -We must first carefully draw a distinction between the vibrations of a -plate or disc which is itself the source of sound, and those vibrations -which are excited in a plate or disc by sound-waves otherwise -originated. If a disc or plate of given size be set in vibration by a -blow or other impulse it will give forth a special sound, according to -the place where it is struck, or it will give forth combinations of -the several tones which it is capable of emitting. On the other hand, -experiment shows that a diaphragm like that used in the telephone—not -only the electric telephone, but such common telephones as have been -sold of late in large quantities in toy shops, etc.—will respond -to any sounds which are properly directed towards it, not merely -reproducing sounds of different tones, but all the peculiarities which -characterize vocal sounds. In the former case, the size of a disc and -the conditions under which it is struck determine the nature of its -vibrations, and the air responds to the vibrations thus excited; in the -latter, the air is set moving in vibrations of a special kind by the -sounds or words uttered, and the disc or diaphragm responds to these -vibrations. Nevertheless, though it is important that this distinction -be recognized, we can still learn, from the behaviour of discs and -plates set in vibration by a blow or other impulse, the laws according -to which the actual motions of the various parts of a vibrating disc -or plate take place. We owe to Chladni the invention of a method for -rendering visible the nature of such motions. - -Certain electrical experiments of Lichtenberg suggested to Chladni -the idea of scattering fine sand over the plate or disc whose motions -he wished to examine. If a horizontal plate covered with fine sand is -set in vibration, those parts which move upwards and downwards scatter -the sand from their neighbourhood, while on those points which undergo -no change of position the sand will remain. Such points are called -_nodes_; and rows of such points are called _nodal lines_, which may be -either straight or curved, according to circumstances. - -If a square plate of glass is held by a suitable clamp at its centre, -and the middle point of a side is touched while a bow is drawn across -the edge near a corner, the sand is seen to gather in the form of a -cross dividing the square into four equal squares—like a cross of St -George. If the finger touches a corner, and the bow is drawn across the -middle of a side, the sand forms a cross dividing the square along its -diagonals—like a cross of St Andrew. Touching two points equidistant -from two corners, and drawing the bow along the middle of the opposite -edge, we get the diagonal cross and also certain curved lines of -sand systematically placed in each of the four quarters into which -the diagonals divide the square. We also have, in this case, a far -shriller note from the vibrating plate. And so, by various changes in -the position of the points clamped by the finger and of the part of the -edge along which the bow is drawn, we can obtain innumerable varieties -of nodal lines and curves along which the sand gathers upon the surface -of the vibrating plate. - -When we take a circular plate of glass, clamped at the middle, and -touching one part of its edge with the finger, draw the bow across a -point of the edge half a quadrant from the finger, we see the sand -arrange itself along two diameters intersecting at right angles. If the -bow is drawn at a point one-third a quadrant from the finger-clamped -point, we get a six-pointed star. If the bow is drawn at a point -a fourth of a quadrant from the finger-clamped point, we get an -eight-pointed star. And so we can get the sand to arrange itself into a -star of any even number of points; that is, we can get a star of four, -six, eight, ten, twelve, etc., points, but not of three, five, seven, -etc. - -In these cases the centre of the plate or disc has been fixed. If, -instead, the plate or disc be fixed by a clip at the edge, or clamped -elsewhere than at the centre, we find the sand arranging itself into -other forms, in which the centre may or may not appear; that is, the -centre may or may not be nodal, according to circumstances. - -A curious effect is produced if very fine powder be strewn along -with the sand over the plate. For it is found that the dust gathers, -not where the nodes or places of no vibration lie, but where the -motion is greatest. Faraday assigns as the cause of this peculiarity -the circumstance that “the light powder is entangled by the little -whirlwinds of air produced by the vibrations of the plate; it cannot -escape from the little cyclones, though the heavier sand particles are -readily driven through them; when, therefore, the motion ceases, the -light powder settles down in heaps at the places where the vibration -was a maximum.” In proof of this theory we have the fact that “in vacuo -no such effect is produced; all powders light and heavy move to the -nodal lines.” (Tyndall on “Sound.”) - -Now if we consider the meaning of such results as these, we shall begin -to recognize the perplexing but also instructive character of the -evidence derived from the telephone, and applied to the construction -of the phonograph. It appears that when a disc is vibrating under such -special conditions as to give forth a particular series of tones (the -so-called fundamental tone of the disc and other tones combined with it -which belong to its series of overtones), the various parts of the disc -are vibrating to and fro in a direction square to the face of the disc, -except certain points at which there is no vibration, these points -together forming curves of special forms along the substance of the -disc. - -When, on the other hand, tones of various kinds are sounded in the -neighbourhood of a disc or of a stretched circular membrane, we may -assume that the different parts of the disc are set in vibration after -a manner at least equally complicated. If the tones belong to the -series which could be emitted by the diaphragm when struck, we can -understand that the vibrations of the diaphragm would resemble those -which would result from a blow struck under special conditions. When -other tones are sounded, it may be assumed that the sound-waves which -reach the diaphragm cause it to vibrate as though not the circumference -(only) but a circle in the substance of the diaphragm—concentric, -of course, with the circumference, and corresponding in dimensions -with the tone of the sounds—were fixed. If a drum of given size is -struck, we hear a note of particular tone. If we heard, as the result -of a blow on the same drum, a much higher tone, we should know that -in some way or other the effective dimensions of the drum-skin had -been reduced—as for instance, by a ring firmly pressed against the -inside of the skin. So when a diaphragm is responding to tones other -than those corresponding to its size, tension, etc., we infer that the -sound-waves reaching it cause it to behave, so far as its effective -vibrating portion is concerned, as though its conformation had altered. -When several tones are responded to by such a diaphragm, we may infer -that the vibrations of the diaphragm are remarkably complicated. - -Now the varieties of vibratory motion to which the diaphragm of the -telephone has been made to respond have been multitudinous. Not only -have all orders of sound singly and together been responded to, but -vocal sounds which in many respects differ widely from ordinary tones -are repeated, and the peculiarities of intonation which distinguish one -voice from another have been faithfully reproduced. - -Let us consider in what respects vocal sounds, and especially the -sounds employed in speech, differ from mere combinations of ordinary -tones. - -It has been said, and with some justice, that the organ of voice -is of the nature of a reed instrument. A reed instrument, as most -persons know, is one in which musical sounds are produced by the -action of a vibrating reed in breaking up a current of air into a -series of short puffs. The harmonium, accordion, concertina, etc., -are reed instruments, the reed for each note being a fine strip of -metal vibrating in a slit. The vocal organ of man is at the top of -the windpipe, along which a continuous current of air can be forced -by the lungs. Certain elastic bands are attached to the head of the -windpipe, almost closing the aperture. These vocal chords are thrown -into vibration by the current of air from the lungs; and as the rate -of their vibration is made to vary by varying their tension, the sound -changes in tone. So far, we have what corresponds to a reed instrument -admitting of being altered in pitch so as to emit different notes. -The mouth, however, affects the character of the sound uttered from -the throat. The character of a _tone_ emitted by the throat cannot be -altered by any change in the configuration of the mouth; so that if a -single tone were in reality produced by the vocal chords, the resonance -of the mouth would only strengthen that tone more or less according to -the figure given to the cavity of the mouth at the will of the singer -or speaker. But in reality, besides the fundamental tone uttered by -the vocal chords, a series of overtones are produced. Overtones are -tones corresponding to vibration at twice, three times, four times, -etc., the rate of the vibration producing the fundamental tone. Now the -cavity of the mouth can be so modified in shape as to strengthen either -the fundamental tone or any one of these overtones. And according as -special tones are strengthened in this way various vocal sounds are -produced, without changing the pitch or intensity of the sound actually -uttered. Calling the fundamental tone the first tone, the overtones -just mentioned the second, third, fourth, etc., tones respectively -(after Tyndall), we find that the following relations exist between the -combinations of these tones and the various vowel sounds:— - -If the lips are pushed forward so as to make the cavity of the mouth -deep and the orifice of the mouth small, we get the deepest resonance -of which the mouth is capable, the fundamental tone is reinforced, -while the higher tones are as far as possible thrown into the shade. -The resulting vowel sound is that of deep U (“oo” in “hoop”). - -If the mouth is so far opened that the fundamental tone is accompanied -by a strong second tone (the next higher octave to the fundamental -tone), we get the vowel sound O (as in “hole”). The third and fourth -tones feebly accompanying the first and second make the sound more -perfect, but are not necessary. - -If the orifice of the mouth is so widened, and the volume of the cavity -so reduced, that the fundamental tone is lost, the second somewhat -weakened, and the third given as the chief tone, with very weak fourth -and fifth tones, we have the vowel sound A. - -To produce the vowel sound E, the resonant cavity of the mouth must be -considerably reduced. The fourth tone is the characteristic of this -vowel. Yet the second tone also must be given with moderate strength. -The first and third tones must be weak, and the fifth tone should be -added with moderate strength. - -To produce the vowel sound A, as in “far,” the higher overtones are -chiefly used, the second is wanting altogether, the third feeble, the -higher tones—especially the fifth and seventh—strong. - -The vowel sound I, as in “fine,” it should be added, is not a simple -sound, but diphthongal. The two sounds whose succession gives the sound -we represent (erroneously) by a single letter I (long), are not very -different from “a” as in “far,” and “ee” (or “i” as in “ravine”); -they, lie, however, in reality, respectively between “a” in “far” and -“fat,” and “i” in “ravine” and “pin.” Thus the tones and overtones -necessary for sounding “I” long, do not require a separate description, -any more than those necessary for sounding other diphthongs, as “oi,” -“oe,” and so forth. - -We see, then, that the sound-waves necessary to reproduce accurately -the various vowel sounds, are more complicated than those which would -correspond to the fundamental tones simply in which any sound may be -uttered. There must not only be in each case certain overtones, but -each overtone must be sounded with its due degree of strength. - -But this is not all, even as regards the vowel sounds, the most -readily reproducible peculiarities of ordinary speech. Spoken sounds -differ from musical sounds properly so called, in varying in pitch -throughout their continuance. So far as tone is concerned, apart from -vowel quality, the speech note may be imitated by sliding a finger up -the finger-board of a violin while the bow is being drawn. A familiar -illustration of the varying pitch of a speech note is found in the -utterance of Hamlet’s question, “Pale, or red?” with intense anxiety of -inquiry, if one may so speak. “The speech note on the word ‘pale’ will -consist of an upward movement of the voice, while that on ‘red’ will -be a downward movement, and in both words the voice will traverse an -interval of pitch so wide as to be conspicuous to ordinary ears; while -the cultivated perception of the musician will detect the voice moving -through a less interval of pitch while he is uttering the word ‘or’ -of the same sentence. And he who can record in musical notation the -sounds which he hears, will perceive the musical interval traversed in -these vocal movements, and the place also of these speech notes on the -musical staff.” Variations of this kind, only not so great in amount, -occur in ordinary speech; and no telephonic or phonographic instrument -could be regarded as perfect, or even satisfactory, which did not -reproduce them. - -But the vowel sounds are, after all, combinations and modifications -of musical tones. It is otherwise with consonantal sounds, which, in -reality, result from various ways in which vowel sounds are commenced, -interrupted (wholly or partially), and resumed. In one respect this -statement requires, perhaps, some modification—a point which has not -been much noticed by writers on vocal sounds. In the case of liquids, -vowel sounds are not partially interrupted only, as is commonly stated. -They cease entirely as vowel sounds, though the utterance of a vocal -sound is continued when a liquid consonant is uttered. Let the reader -utter any word in which a liquid occurs, and he will find that while -the liquid itself is sounded the vowel sounds preceding or following -the liquid cease entirely. Repeating slowly, for example, the word -“remain,” dwelling on all the liquids, we find that while the “r” is -being sounded the “ē” sound cannot be given, and this sound ceases so -soon as the “m” is sounded; similarly the long “a” sound can only be -uttered when the “m” sound ceases, and cannot be carried on into the -sound of the final liquid “n.” The liquids are, in fact, improperly -called semi-vowels, since no vowel sound can accompany their utterance. -The tone, however, with which they are sounded can be modified during -their utterance. In sounding labials the emission of air is not stopped -completely at any moment. The same is true of the sibilants s, z, sh, -zh, and of the consonants g, j, f, v, th (hard and soft). These are -called, on this account, _continuous_ consonants. The only consonants -in pronouncing which the emission of air is for a moment entirely -stopped, are the true mutes, sometimes called the six _explosive_ -consonants, b, p, t, d, k, and g. - -To reproduce artificially sounds resembling those of the consonants -in speech, we must for a moment interrupt, wholly for explosive and -partially for continuous consonant sounds, the passage of air through a -reed pipe. Tyndall thus describes an experiment of this kind in which -an imperfect imitation of the sound of the letter “m” was obtained—an -imitation only requiring, to render it perfect, as I have myself -experimentally verified, attention to the consideration respecting -liquids pointed out in the preceding paragraph. “Here,” says Tyndall, -describing the experiment as conducted during a lecture, “is a free -reed fixed in a frame, but without any pipe associated with it, mounted -on the acoustic bellows. When air is urged through the orifice, it -speaks in this forcible manner. I now fix upon the frame of the reed -a pyramidal pipe; you notice a change in the clang, and, by pushing -my flat hand over the open end of the pipe, the similarity between -the sounds produced and those of the human voice is unmistakable. -Holding the palm of my hand over the end of the pipe, so as to close -it altogether, and then raising my hand twice in quick succession, the -word ‘mamma’ is heard as plainly as if it were uttered by an infant. -For this pyramidal tube I now substitute a shorter one, and with it -make the same experiment. The ‘mamma’ now heard is exactly such as -would be uttered by a child with a stopped nose. Thus, by associating -with a vibrating reed a suitable pipe, we can impart to the sound of -the reed the qualities of the human voice.” The “m” obtained in these -experiments was, however, imperfect. To produce an “m” sound such as an -adult would utter without a “stopped nose,” all that is necessary is -to make a small opening (experiment readily determines the proper size -and position) in the side of the pyramidal pipe, so that, as in the -natural utterance of this liquid, the emission of air is not altogether -interrupted. - -I witnessed in 1874 some curious illustrations of the artificial -production of vocal sounds, at the Stevens Institute, Hoboken, -N.J., where the ingenious Professor Mayer (who will have, I trust, -a good deal to say about the scientific significance of telephonic -and phonographic experiments before long) has acoustic apparatus, -including several talking-pipes. By suitably moving his hand on the top -of some of these pipes, he could make them speak certain words with -tolerable distinctness, and even utter short sentences. I remember -the performance closed with the remarkably distinct utterance, by one -profane pipe, of the words euphemistically rendered by Mark Twain (in -his story of the Seven Sleepers, I think), “Go thou to Hades!” - -Now, the speaking diaphragm in the telephone, as in the phonograph, -presently to be described, must reproduce not only all the varieties -of sound-wave corresponding to vowel sounds, with their intermixtures -of the fundamental tone and its overtones and their inflexions or -sliding changes of pitch, but also all the effects produced on the -receiving diaphragm by those interruptions, complete or partial, of -aerial emission which correspond to the pronunciation of the various -consonant sounds. It might certainly have seemed hopeless, from all -that had been before known or surmised respecting the effects of aerial -vibrations on flexible diaphragms, to attempt to make a diaphragm speak -artificially—in other words, to make the movements of all parts of -it correspond with those of a diaphragm set in vibration by spoken -words—by movements affecting only its central part. It is in the -recognition of the possibility of this, or rather in the discovery -of the fact that the movements of a minute portion of the middle of -a diaphragm regulate the vibratory and other movements of the entire -diaphragm, that the great scientific interest of Professor Graham -Bell’s researches appears to me to reside. - -It may be well, in illustration of the difficulties with which formerly -the subject appeared to be surrounded, to describe the results of -experiments which preceded, though they can scarcely be said to have -led up to, the invention of artificial ways of reproducing speech. -I do not now refer to experiments like those of Kratzenstein of -St. Petersburg, and Von Kempelen of Vienna, in 1779, and the more -successful experiments by Willis in later years, but to attempts -which have been made to obtain material records of the aerial motions -accompanying the utterance of spoken words. The most successful of -these attempts was that made by Mr. W. H. Barlow. His purpose was “to -construct an instrument which should record the pneumatic actions” -accompanying the utterance of articulated sounds “by diagrams, in -a manner analogous to that in which the indicator-diagram of a -steam-engine records the action of the engine.” He perceived that the -actual aerial pressures involved being very small and very variable, -and the succession of impulses and changes of pressure being very -rapid, it was necessary that the moving parts should be very light, -and that the movement and marking should be accomplished with as -little friction as possible. The instrument he constructed consisted -of a small speaking-trumpet about four inches long, having an ordinary -mouthpiece connected to a tube half an inch in diameter, the thin end -of which widened out so as to form an aperture of 2¼ inches diameter. -This aperture was covered with a membrane of goldbeater’s skin, or thin -gutta-percha. A spring carrying a marker was made to press against the -membrane with a slight initial pressure, to prevent as far as possible -the effects of jarring and consequent vibratory action. A light arm -of aluminium was connected with the spring, and held the marker; and -a continuous strip of paper was made to pass under the marker in the -manner employed in telegraphy. The marker consisted of a small, fine -sable brush, placed in a light tube of glass one-tenth of an inch in -diameter, the tube being rounded at the lower end, and pierced with a -hole about one-twentieth of an inch in diameter. Through this hole the -tip of the brush projected, and was fed by colour put into the glass -tube by which it was held. It should be added that, to provide for the -escape of air passing through the speaking-trumpet, a small opening -was made in the side, so that the pressure exerted upon the membrane -was that due to the excess of air forced into the trumpet over that -expelled through the orifice. The strength of the spring which carried -the marker was so adjusted to the size of the orifice that, while the -lightest pressures arising under articulation could be recorded, the -greatest pressures should not produce a movement exceeding the width of -the paper. - -“It will be seen,” says Mr. Barlow, “that in this construction of the -instrument the sudden application of pressure is as suddenly recorded, -subject only to the modifications occasioned by the inertia, momentum, -and friction of the parts moved. But the record of the sudden cessation -of pressure is further affected by the time required to discharge the -air through the escape-orifice. Inasmuch, however, as these several -effects are similar under similar circumstances, the same diagram -should always be obtained from the same pneumatic action when the -instrument is in proper adjustment; and this result is fairly borne out -by the experiments.” - -The defect of the instrument consisted in the fact that it recorded -changes of pressure only; and in point of fact it seems to result, -from the experiments made with it, that it could only indicate the -order in which explosive, continuant, and liquid consonants succeeded -each other in spoken words, the vowels being all expressed in the -same way, and only one letter—the rough R, or R with a burr—being -always unmistakably indicated. The explosives were represented by a -sudden sharp rise and fall in the recorded curve; the height of the -rise depending on the strength with which the explosive is uttered, -not on the nature of the consonant itself. Thus the word “tick” is -represented by a higher elevation for the “t” than for the “k,” but the -word “kite” by a higher elevation for the “k” than for the “t.” It is -noteworthy that there is always a second smaller rise and fall after -the first chief one, in the case of each of the explosives. This shows -that the membrane, having first been forcibly distended by the small -aerial explosion accompanying the utterance of such a consonant, sways -back beyond the position where the pressure and the elasticity of the -membrane would (for the moment) exactly balance, and then oscillates -back again over that position before returning to its undistended -condition. Sometimes a third small elevation can be recognized, -and when an explosive is followed by a rolling “r” several small -elevations are seen. The continuous consonants produce elevations less -steep and less high; aspirates and sibilants give rounded hills. But -the results vary greatly according to the position of a consonant; and, -so far as I can make out from a careful study of the very interesting -diagrams accompanying Mr. Barlow’s paper, it would be quite impossible -to define precisely the characteristic records even of each order of -consonantal sounds, far less of each separate sound. - -We could readily understand that the movement of the central part of -the diaphragm in the telephone should give much more characteristic -differences for the various sounds than Barlow’s logograph. For if -we imagine a small pointer attached to the centre of the face of the -receiving diaphragm while words are uttered in its neighbourhood, the -end of that pointer would not only move to and fro in a direction -square to the face of the diaphragm, as was the case with Barlow’s -marker, but it would also sway round its mean position in various small -circles or ovals, varying in size, shape, and position, according to -the various sounds uttered. We might expect, then, that if in any way -a record of the actual motions of the extremity of that small pointer -could be obtained, in such sort that its displacement in directions -square to the face of the diaphragm, as well as its swayings around -its mean position, would be indicated in some pictorial manner, the -study of such records would indicate the exact words spoken near the -diaphragm, and even, perhaps, the precise tones in which they were -uttered. For Barlow’s logograph, dealing with one only of the orders -of motion (really triple in character), gives diagrams in which the -general character of the sounds uttered is clearly indicated, and the -supposed records would show much more. - -But although this might, from _à priori_ considerations, have been -reasonably looked for, it by no means follows that the actual results -of Bell’s telephonic experiments could have been anticipated. That the -movement of the central part of the diaphragm should suffice to show -that such and such words had been uttered, is one thing; but that these -movements should of themselves suffice, if artificially reproduced, to -cause the diaphragm to reproduce these words, is another and a very -different one. I venture to express my conviction that at the beginning -of his researches Professor Bell can have had very little hope that -any such result would be obtained, notwithstanding some remarkable -experiments respecting the transmission of sound which we can _now_ -very clearly perceive to point in that direction. - -When, however, he had invented the telephone, this point was in effect -demonstrated; for in that instrument, as we have seen, the movements -of the minute piece of metal attached (at least in the earlier forms -of the instrument) to the centre of the receiving membrane, suffice, -when precisely copied by the similar central piece of metal in the -transmitting membrane, to cause the words which produced the motions of -the receiving or hearing membrane to be uttered (or seem to be uttered) -by the transmitting or speaking membrane. - -It was reserved, however, for Edison (of New Jersey, U.S.A., Electrical -Adviser to the Western Union Telegraph Company) to show how advantage -might be taken of this discovery to make a diaphragm speak, not -directly through the action of the movements of a diaphragm affected by -spoken words or other sounds, and therefore either simultaneously with -these or in such quick succession after them as corresponds with the -transmission of their effects along some line of electrical or other -communication, but by the mechanical reproduction of similar movements -at any subsequent time (within certain limits at present, but probably -hereafter with practically unlimited extension as to time). - -The following is slightly modified from Edison’s own description of the -phonograph:— - -The instrument is composed of three parts mainly; namely, a receiving, -a recording, and a transmitting apparatus. The receiving apparatus -consists of a curved tube, one end of which is fitted with a -mouthpiece. The other end is about two inches in diameter, and is -closed with a disc or diaphragm of exceedingly thin metal, capable of -being thrust slightly outwards or vibrated upon gentle pressure being -applied to it from within the tube. To the centre of this diaphragm -(which is vertical) is fixed a small blunt steel pin, which shares the -vibratory motion of the diaphragm. This arrangement is set on a table, -and can be adjusted suitably with respect to the second part of the -instrument—the recorder. This is a brass cylinder, about four inches -in length and four in diameter, cut with a continuous V-groove from -one end to the other, so that in effect it represents a large screw. -There are forty of these grooves in the entire length of the cylinder. -The cylinder turns steadily, when the instrument is in operation, -upon a vertical axis, its face being presented to the steel point of -the receiving apparatus. The shaft on which it turns is provided with -a screw-thread and works in a screwed bearing, so that as the shaft -is turned (by a handle) it not only turns the cylinder, but steadily -carries it upwards. The rate of this vertical motion is such that the -cylinder behaves precisely as if its groove worked in a screw-bearing. -Thus, if the pointer be set opposite the middle of the uppermost part -of the continuous groove at the beginning of this turning motion, it -will traverse the groove continuously to its lowest part, which it will -reach after forty turnings of the handle. (More correctly, perhaps, we -might say that the groove continuously traverses past the pointer.) -Now, suppose that a piece of some such substance as tinfoil is wrapped -round the cylinder. Then the pointer, when at rest, just touches the -tinfoil. But when the diaphragm is vibrating under the action of aerial -waves resulting from various sounds, the pointer vibrates in such a way -as to indent the tinfoil—not only to a greater or less depth according -to the play of the pointer to and fro in a direction square to the face -of the diaphragm, but also over a range all round its mean position, -corresponding to the play of the end of the pointer around _its_ mean -position. The groove allows the pressure of the pointer against the -tinfoil free action. If the cylinder had no groove the dead resistance -of the tinfoil, thus backed up by an unyielding surface, would stop -the play of the pointer. Under the actual conditions, the tinfoil -is only kept taut enough to receive the impressions, while yielding -sufficiently to let the play of the pointer continue unrestrained. -If now a person speaks into the receiving tube, and the handle of -the cylinder be turned, the vibrations of the pointer are impressed -upon the portion of the tinfoil lying over the hollow groove, and are -retained by it. They will be more or less deeply marked according to -the quality of the sounds emitted, and according also, of course, to -the strength with which the speaker utters the sounds, and to the -nature of the modulations and inflexions of his voice. The result is -a message verbally imprinted upon a strip of metal. It differs from -the result in the case of Barlow’s logograph, in being virtually a -record in three dimensions instead of one only. The varying depth of -the impressions corresponds to the varying height of the curve in -Barlow’s diagrams; but there the resemblance ceases; for that was -the single feature which Barlow’s logographs could present. Edison’s -imprinted words show, besides varying depth of impression, a varying -range on either side of the mean track of the pointer, and also—though -the eye is not able to detect this effect—there is a varying rate of -progression according as the end of the pointer has been swayed towards -or from the direction in which, owing to the motion of the cylinder, -the pointer is virtually travelling. - -We may say of the record thus obtained that it is sound presented -in a visible form. A journalist who has written on the phonograph -has spoken of this record as corresponding to the crystallization of -sound. And another who, like the former, has been (erroneously, but -that is a detail) identified with myself, has said, in like fanciful -vein, that the story of Baron Münchausen hearing words which had been -frozen during severe cold melting into speech again, so that all the -babble of a past day came floating about his ears, has been realized -by Edison’s invention. Although such expressions may not be, and in -point of fact are not, strictly scientific, I am not disposed, for my -own part, to cavil with them. If they could by any possibility be taken -_au pied de la lettre_ (and, by the way, we find quite a new meaning -for this expression in the light of what is now known about vowels -and consonants), there would be valid objection to their use. But, as -no one supposes that Edison’s phonograph really crystallizes words or -freezes sounds, it seems hypercritical to denounce such expressions as -the critic of the _Telegraphic Journal_ has denounced them. - -To return to Edison’s instrument. - -Having obtained a material record of sounds, vocal or otherwise, -it remains that a contrivance should be adopted for making this -record reproduce the sounds by which it was itself formed. This is -effected by a third portion of the apparatus, the transmitter. This -is a conical drum, or rather a drum shaped like a frustum of a cone, -having its larger end open, the smaller—which is about two inches in -diameter—being covered with paper stretched tight like the parchment -of a drumhead. In front of this diaphragm is a light flat steel spring, -held vertically, and ending in a blunt steel point, which projects -from it and corresponds precisely with that on the diaphragm of the -receiver. The spring is connected with the paper diaphragm by a silken -thread, just sufficiently in tension to cause the outer face of the -diaphragm to be slightly convex. Having removed the receiving apparatus -from the cylinder and set the cylinder back to its original position, -the transmitting apparatus is brought up to the cylinder until the -steel point just rests, without pressure, in the first indentation -made in the tinfoil by the point of the receiver. If now the handle is -turned at the same speed as when the message was being recorded, the -steel point will follow the line of impression, and will vibrate in -periods corresponding to the impressions which were produced by the -point of the receiving apparatus. The paper diaphragm being thus set -into vibrations of the requisite kind in number, depth, and side-range, -there are produced precisely the same sounds that set the diaphragm of -the receiver into vibration originally. Thus the words of the speaker -are heard issuing from the conical drum in his own voice, tinged -with a slightly metallic or mechanical tone. If the cylinder be more -slowly turned when transmitting than it had been when receiving the -message, the voice assumes a base tone; if more quickly, the message -is given with a more treble voice. “In the present machine,” says the -account, “when a long message is to be recorded, so soon as one strip -of tinfoil is filled, it is removed and replaced by others, until the -communication has been completed. In using the machine for the purpose -of correspondence, the metal strips are removed from the cylinder -and sent to the person with whom the speaker desires to correspond, -who must possess a machine similar to that used by the sender. The -person receiving the strips places them in turn on the cylinder of -his apparatus, applies the transmitter, and puts the cylinder in -motion, when he hears his friend’s voice speaking to him from the -indented metal. And he can repeat the contents of the missive as often -as he pleases, until he has worn the metal through. The sender can -make an infinite number of copies of his communication by taking a -plaster-of-Paris cast of the original, and rubbing off impressions from -it on a clean sheet of foil.” - -I forbear from dwelling further on the interest and value of this -noble invention, or of considering some of the developments which it -will probably receive before long, for already I have occupied more -space than I had intended. I have no doubt that in these days it will -bring its inventor less credit, and far less material gain, than would -be acquired from the invention of some ingenious contrivance for -destroying many lives at a blow, bursting a hole as large as a church -door in the bottom of an ironclad, or in some other way helping men to -carry out those destructive instincts which they inherit from savage -and brutal ancestors. But hereafter, when the representatives of the -brutality and savagery of our nature are held in proper disesteem, and -those who have added new enjoyments to life are justly valued, a high -place in the esteem of men will be accorded to him who has answered -one-half of the poet’s aspiration, - - “Oh for the touch of a vanished hand, - And the sound of a voice that is still!” - - * * * * * - -NOTE.—Since the present paper was written, M. Aurel de Ratti has -made some experiments which he regards as tending to show that there -is no mechanical vibration. Thus, “when the cavities above and below -the iron disc of an ordinary telephone are filled with wadding, the -instrument will transmit and speak with undiminished clearness. On -placing a finger on the iron disc opposite the magnet, the instrument -will transmit and speak distinctly, only ceasing to act when sufficient -pressure is applied to bring plate and magnet into contact. Connecting -the centre of the disc by means of a short thread with an extremely -sensitive membrane, no sound is given out by the latter when a message -is transmitted. Bringing the iron cores of the double telephone in -contact with the disc, and pressing with the fingers against the -plate on the other side, a weak current from a Daniell cell produced -a distinct click in the plate, and on drawing a wire from the cell -over a file which formed part of the circuit, a rattling noise was -produced in the instrument.” If these experiments had been made -before the phonograph was invented, they would have suggested the -impracticability of constructing any instrument which would do what the -phonograph actually does, viz., cause sounds to be repeated by exciting -a merely mechanical vibration of the central part of a thin metallic -disc. But as the phonograph proves that this can actually be done, -we must conclude that M. Aurel de Ratti’s experiments will not bear -the interpretation he places upon them. They show, nevertheless, that -exceedingly minute vibrations of probably a very small portion of the -telephonic disc suffice for the distinct transmission of vocal sounds. -This might indeed be inferred from the experiments of M. Demozet, of -Nantes, who finds that the vibrations of the transmitting telephone -are in amplitude little more than 1-2000th those of the receiving -telephone. - - - - -_THE GORILLA AND OTHER APES._ - - -About twenty-five centuries ago, a voyager called Hanno is said to -have sailed from Carthage, between the Pillars of Hercules—that is, -through the Straits of Gibraltar—along the shores of Africa. “Passing -the Streams of Fire,” says the narrator, “we came to a bay called the -Horn of the South. In the recess there was an island, like the first, -having a lake, and in this there was another island full of wild men. -But much the greater part of them were women, with hairy bodies, whom -the interpreters called ‘Gorillas.’ Pursuing them, we were not able to -take the men; they all escaped, being able to climb the precipices; -and defended themselves with pieces of rock. But three women, who bit -and scratched those who led them, were not willing to follow. However, -having killed them, we flayed them, and conveyed the skins to Carthage; -for we did not sail any further, as provisions began to fail.”[35] - -In the opinion of many naturalists, the wild men of this story -were the anthropoid or manlike apes which are now called gorillas, -rediscovered recently by Du Chaillu. The region inhabited by the -gorillas is a well-wooded country, “extending about a thousand miles -from the Gulf of Guinea southward,” says Gosse; “and as the gorilla -is not found beyond these limits, so we may pretty conclusively infer -that the extreme point of Hanno was somewhere in this region.” I must -confess these inferences seem to me somewhat open to question, and -the account of Hanno’s voyage only interesting in its relation to the -gorilla, as having suggested the name now given to this race of apes. -It is not probable that Hanno sailed much further than Sierra Leone; -according to Rennell, the island where the “wild men” were seen, was -the small island lying close to Sherbro, some seventy miles south of -Sierra Leone. To have reached the gorilla district after doubling Cape -Verd—which is itself a point considerably south of the most southerly -city founded by Hanno—he would have had to voyage a distance exceeding -that of Cape Verd from Carthage. Nothing in the account suggests that -the portion of the voyage, after the colonizing was completed, had -so great a range. The behaviour of the “wild men,” again, does not -correspond with the known habits of the gorilla. The idea suggested -is that of a species of anthropoid ape far inferior to the gorilla in -strength, courage, and ferocity. - -The next accounts which have been regarded as relating to the gorilla -are those given by Portuguese voyagers. These narratives have been -received with considerable doubt, because in some parts they seem -manifestly fabulous. Thus the pictures representing apes show also -huge flying dragons with a crocodile’s head; and we have no reason for -believing that batlike creatures like the pterodactyls of the greensand -existed in Africa or elsewhere so late as the time of the Portuguese -voyages of discovery. Purchas, in his history of Andrew Battell, -speaks of “a kinde of great apes, if they might so bee termed, of the -height of a man, but twice as bigge in feature of their limmes, with -strength proportionable, hairie all over, otherwise altogether like -men and women in their whole bodily shape, except that their legges -had no calves.” This description accords well with the peculiarities -of gorillas, and may be regarded as the first genuine account of these -animals. Battell’s contemporaries called the apes so described Pongoes. -It is probable that in selecting the name Pongo for the young gorilla -lately at the Westminster Aquarium, the proprietors of this interesting -creature showed a more accurate judgment of the meaning of Purchas’s -narrative than Du Chaillu showed of Hanno’s account, in calling the -great anthropoid ape of the Gulf of Guinea a gorilla. - -I propose here briefly to sketch the peculiarities of the four apes -which approach nearest in form to man—the gorilla, the chimpanzee, the -orang-outang, and the gibbon; and then, though not dealing generally -with the question of our relationship to these non-speaking (and, in -some respects, perhaps, “unspeakable”) animals, to touch on some points -connected with this question, and to point out some errors which are -very commonly entertained on the subject. - -It may be well, in the first place, to point out that the terms “ape,” -“baboon,” and “monkey” are no longer used as they were by the older -naturalists. Formerly the term “ape” was limited to tailless simians -having no cheek-pouches, and the same number of teeth as man; the -term “baboon” to short-tailed simians with dog-shaped heads; and the -term “monkey,” unless used generically, to the long-tailed species. -This was the usage suggested by Ray, and adopted systematically -thirty or forty years ago. But it is no longer followed, though no -uniform classification has been substituted for the old arrangement. -Thus Mivart divides the apes into two classes—calling the first the -_Simiadæ_, or Old World apes; and the second the _Cebidæ_, or New World -apes. He subdivides the _Simiadæ_ into (1) the _Siminæ_, including the -gorilla, chimpanzee, orang, and gibbon; (2) the _Semnopithecinæ_; and -(3) the _Cynopithecinæ_; neither of which subdivisions will occupy much -of our attention here, save as respects the third subdivision of the -_Cynopithecinæ_, viz., the _Cynocephali_, which includes the baboons. -The other great division, the _Cebidæ_, or New World apes, are for the -most part very unlike the Old World apes. None of them approach the -gorilla or orang-outang in size; most of them are long-tailed; and the -number and arrangement of the teeth is different. The feature, however, -which most naturalists have selected as the characteristic distinction -between the apes of the Old World and of the New World is the position -of the nostrils. The former are called Catarhine, a word signifying -that the nostrils are directed downwards; the latter are called -Platyrhine, or broad-nosed. The nostrils of all the Old World apes are -separated by a narrow cartilaginous plate or septum, whereas the septum -of the New World apes is broad. After the apes come, according to -Mivart’s classification, the half-apes or lemuroids. - -I ought, perhaps, to have mentioned that Mivart, in describing the -lemuroids as the second sub-order of a great order of animals, the -Primates, speaks of a man as (zoologically speaking) belonging to the -first sub-order. So that, in point of fact, the two sub-orders are the -Anthropoids, including the Anthropos (man) and the Lemuroids, including -the lemur. - -The classification here indicated will serve our present purpose -very well. But the reader is reminded that, as already mentioned, -naturalists do not adopt at present any uniform system of -classification. Moreover, the term _Simiadæ_ is usually employed—and -will be employed here—to represent the entire simian race, _i.e._, -both the Simiadæ and the Cebidæ of Mivart’s classification. - -And now, turning to the Anthropoid apes, we find ourselves at the -outset confronted by the question, Which of the four apes, the gorilla, -the orang-outang, the chimpanzee, or the gibbon, is to be regarded -as nearest to man in intelligence? So far as bodily configuration is -concerned, our opinion would vary according to the particular feature -which we selected for consideration. But it will probably be admitted -that intelligence should be the characteristic by which our opinions -should be guided. - -The gibbon may be dismissed at once, though, as will presently appear, -there are some features in which this ape resembles man more closely -than either the gorilla, the orang-outang, or the chimpanzee. - -The gorilla must, I fear, be summarily ejected from the position of -honour to which he has been raised by many naturalists. Though the -gorilla is a much larger animal than the chimpanzee, his brain barely -equals the chimpanzee’s in mass. It is also less fully developed in -front. In fact Gratiolet asserts that of all the broad-chested apes, -the gorilla is—so far as brain character is concerned—the lowest -and most degraded. He regards the gorilla’s brain as only a more -advanced form of that of the brutal baboons, while the orang’s brain -is the culminating form of the gibbon type, and the chimpanzee’s the -culminating form of the macaque type. This does not dispose of the -difficulty very satisfactorily, however, because it remains to be shown -whether the gibbon type and the macaque type are superior as types to -the baboon types. But it may suffice to remark that the baboons are -all brutal and ferocious, whereas the gibbons are comparatively gentle -animals, and the macaques docile and even playful. It may be questioned -whether brutality and ferocity should be regarded as necessarily -removing the gorilla further from man; because it is certain that the -races of man which approach nearest to the anthropoid apes, with which -races the comparison should assuredly be made, are characterized by -these very qualities, brutality and ferocity. Intelligence must be -otherwise gauged. Probably the average proportion of the brain’s weight -to that of the entire body, and the complexity of the structure of -the brain, would afford the best means of deciding the question. But, -unfortunately, we have very unsatisfactory evidence on these points. -The naturalists who have based opinions on such evidence as has been -obtained, seem to overlook the poverty of the evidence. Knowing as we -do how greatly the human brain varies in size and complexity, not only -in different races, but in different individuals of the same race, it -appears unsatisfactory in the extreme to regard the average of the -brains of each simian species hitherto examined as presenting the true -average cerebral capacity for each species. - -Still it seems tolerably clear that the choice as to the race of apes -which must be regarded as first in intelligence, and therefore as on -the whole the most manlike, rests between the orang-outang and the -chimpanzee. “In the world of science, as in that of politics,” said -Professor Rolleston in 1862, “France and England have occasionally -differed as to their choice between rival candidates for royalty. If -either hereditary claims or personal merits affect at all the right -of succession, beyond a question the gorilla is but a pretender, and -one or other of the two (other) candidates the true prince. There is -a graceful as well as an ungraceful way of withdrawing from a false -position, and the British public will adopt the graceful course -by accepting forthwith and henceforth the French candidate”—the -orang-outang. If this were intended as prophecy, it has not been -fulfilled by the event, for the gorilla is still regarded by most -British naturalists as the ape which comes on the whole nearest to man; -but probably, in saying “the British public will adopt the graceful -course” in accepting the orang-outang as “the king of the Simiadæ,” -Professor Rolleston meant only that that course would be graceful if -adopted. - -Before the discovery of the gorilla, the chimpanzee was usually -regarded as next to man in the scale of the animal creation. It was -Cuvier who first maintained the claim of the orang-outang to this -position. Cuvier’s opinion was based on the greater development -of the orang-outang’s brain, and the height of its forehead. But -these marks of superiority belong to the orang only when young. The -adult orang seems to be inferior, or at least not superior, to the -chimpanzee as respects cerebral formation, and in other respects seems -less to resemble man. The proportions of his body, his long arms, -high shoulders, deformed neck, and imperfect ears are opposed to its -claims to be regarded as manlike. In all these respects, save one, the -chimpanzee seems to be greatly its superior. (The ear of the chimpanzee -is large, and not placed as with us: that of the gorilla is much more -like man’s.) - -As to the intelligence exhibited in the conduct of the chimpanzee and -orang-outang, various opinions may be formed according to the various -circumstances under which the animals are observed. The following -has been quoted in evidence of the superiority of the chimpanzee in -this respect:—“About fifty years ago, a young chimpanzee and an -orang-outang of about the same age were exhibited together at the -Egyptian Hall. The chimpanzee, though in a declining state of health, -and rendered peevish and irritable by bodily suffering, exhibited -much superior marks of intelligence to his companion; he was active, -quick, and observant of everything that passed around him; no new -visitor entered the apartment in which he was kept, and no one left it, -without attracting his attention. The orang-outang, on the contrary, -exhibited a melancholy and a disregard of passing occurrences almost -amounting to apathy; and though in the enjoyment of better health, was -evidently much inferior to his companion in quickness and observation. -On one occasion, when the animals were dining on potatoes and boiled -chicken, and surrounded as usual with a large party of visitors, the -orang-outang allowed her plate to be taken without exhibiting the least -apparent concern. Not so, however, the chimpanzee. We took advantage -of an opportunity when his head was turned (to observe a person coming -in) to secrete his plate also. For a few seconds he looked round to -see what had become of it, but, not finding it, began to pout and fret -exactly like a spoiled child, and perceiving a young lady, who happened -to be standing near him, laughing, perhaps suspecting her to be the -delinquent, he flew at her in the greatest rage, and would probably -have bitten her had she not got beyond his reach. Upon having his plate -restored, he took care to prevent the repetition of the joke by holding -it firmly with one hand, while he fed himself with the other.” - -This story can hardly be regarded as deciding the question in favour -of the chimpanzee. Many animals, admittedly far inferior to the lowest -order of monkeys in intelligence, show watchfulness over their food, -and as much ill-temper when deprived of it, and as much anxiety to -recover it, as this chimpanzee did. A hundred cases in point might -readily be cited.[36] - -Perhaps the soundest opinion respecting the relative position of -the gorilla, chimpanzee, and orang-outang with reference to man, is -that which places the gorilla nearest to the lower tribes of man now -inhabiting Africa, the chimpanzee approximating, but not so closely, -to higher African tribes, and the orang-outang approximating, but -still less closely, to Asiatic tribes. It appears to me that, whatever -weight naturalists may attach to those details in which the gorilla -and the chimpanzee are more removed from man than the orang, no one -who takes a _general_ view of these three races of anthropoid apes can -hesitate to regard the gorilla as that which, on the whole, approaches -nearest to man; but it is to a much lower race of man that the gorilla -approximates, so that the chimpanzee and the orang-outang may fairly be -regarded as higher in the scale of animal life. - -If we consider young specimens of the three animals, which is, on -the whole, the safest way of forming an opinion, we are unmistakably -led, in my judgment, to such a conclusion. I have seen three or four -young chimpanzees, two young orangs, and the young gorilla lately -exhibited at the Aquarium (where he could be directly compared with -the chimpanzee), and I cannot hesitate to pronounce Pongo altogether -the most human of the three. A young chimpanzee reminds one rather of -an old man than of a child, and the same may be said of young orangs; -but the young gorilla unmistakably reminds one of the young negro. -Repeatedly, while watching Pongo, I was reminded of the looks and -behaviour of young negroes whom I had seen in America, though not able -in every case to fix definitely on the feature of resemblance which -recalled the negro to my mind. (The reader is, doubtless, familiar with -half-remembered traits such as those I refer to—traits, for instance, -such as assure you that a person belongs to some county or district, -though you may be unable to say what feature, expression, or gesture -suggests the idea.) One circumstance may be specially noted, not only -as frequently recurring, but as illustrating the traits on which the -resemblance of the gorilla (when young, at any rate) to the negro -depends. A negro turns his eyes where a Caucasian would turn his head. -The peculiarity is probably a relic of savage life; for the savage, -whether engaged in war or in the chase, avoids, as far as possible, -every movement of body or limb. Pongo looked in this way. When he thus -cast his black eyes sideways at an object I found myself reminded -irresistibly of the ways of the watchful negro waiters at an American -hotel. Certainly there is little in the movements of the chimpanzee to -remind one of any kind of human child. He is impish; but not the most -impish child of any race or tribe ever had ways, I should suppose, -resembling his. - -The four anthropoid apes, full grown and in their native wilds, differ -greatly from each other in character. It may be well to consider their -various traits, endeavouring to ascertain how far diversities existing -among them may be traced to the conditions under which the four orders -subsist. - -The gorilla occupies a well-wooded country extending along the coast -of Africa from the Gulf of Guinea southwards across the equator. When -full grown he is equal to a man in height, but much more powerfully -built. “Of specimens shot by Du Chaillu,” says Rymer Jones, “the -largest male seems to have been at least six feet two in height; -so that, making allowance for the shortness of the lower limbs, the -dimensions of a full-grown male may be said to equal those of a man of -eight or nine feet high, and it is only in their length that the lower -limbs are disproportionate to the gigantic trunk. In the thickness and -solidity of their bones, and in the strength of their muscles, these -limbs are quite in keeping with the rest of the body. When upright, -the gorilla’s arms reach to his knees; the hind hands are wide, and of -amazing size and power; the great toe or thumb measures six inches in -circumference; the palms and soles, and the naked part of the face, are -of an intense black colour, as is also the breast. The other parts are -thickly clothed with hair of an iron grey, except the head, on which it -is reddish brown, and the arms, where it is long and nearly black. The -female is wholly tinged with red.” - -Du Chaillu gives the following account of the aspect of the gorilla -in his native woods:—“Suddenly, as we were yet creeping along in a -silence which made even a heavy breath seem loud and distinct, the -woods were at once filled with a tremendous barking roar; then the -underbrush swayed rapidly just ahead, and presently stood before us an -immense gorilla. He had gone through the jungle on all-fours; but when -he saw our party he erected himself and looked us boldly in the face. -He stood about a dozen yards from us, and was a sight I think I shall -never forget. Nearly six feet high (he proved four inches shorter), -with immense body, huge chest, and great muscular arms, with fiercely -glaring, large, deep-grey eyes, and a hellish expression of face, which -seemed to me some night-mare vision; thus stood before us the king of -the African forest. He was not afraid of us; he stood there and beat -his breasts with his large fists till it resounded like an immense bass -drum (which is their mode of bidding defiance), meantime giving vent to -roar after roar.” - -The gorilla is a fruit-eater, but as fierce as the most carnivorous -animals. He is said to show an enraged enmity against men, probably -because he has found them not only hostile to himself, but successful -in securing the fruits which the gorilla loves, for he shows a similar -hatred to the elephant, which also seeks these fruits. We are told -that when the gorilla “sees the elephant busy with his trunk among -the twigs, he instantly regards this as an infraction of the laws -of property, and, dropping silently down to the bough, he suddenly -brings his club smartly down on the sensitive finger of the elephant’s -proboscis, and drives off the alarmed animal trumpeting shrilly with -rage and pain.” His enmity to man is more terribly manifested. “The -young athletic negroes in their ivory-haunts,” says Gosse, “well know -the prowess of the gorilla. He does not, like the lion, sullenly -retreat on seeing them, but swings himself rapidly down to the lower -branches, courting the conflict, and clutches the nearest of his -enemies. The hideous aspect of his visage (his green eyes flashing -with rage) is heightened by the thick and prominent brows being drawn -spasmodically up and down, with the hair erect, causing a horrible -and fiendish scowl. Weapons are torn from their possessor’s grasp, -gun-barrels bent and crushed in by the powerful hands and vice-like -teeth of the enraged brute. More horrid still, however, is the sudden -and unexpected fate which is often inflicted by him. Two negroes will -be walking through one of the woodland paths unsuspicious of evil, when -in an instant one misses his companion, or turns to see him drawn up -in the air with a convulsed choking cry, and in a few minutes dropped -to the ground, a strangled corpse. The terrified survivor gazes up, -and meets the grin and glare of the fiendish giant, who, watching his -opportunity, had suddenly put down his immense hind hand, caught the -wretch by the neck with resistless power, and dropped him only when he -ceased to struggle.” - -The chimpanzee inhabits the region from Sierra Leone to the southern -confines of Angola, possibly as far as Cape Negro, so that his domain -includes within it that of the gorilla. He attains almost the same -height as the gorilla when full grown, but is far less powerfully -built. In fact, in general proportions the chimpanzee approaches man -more nearly than does any other animal. His body is covered with long -black coarse hair, thickest on the head, shoulders, and back, and -rather thin on the breast and belly. The face is dark brown and naked, -as are the ears, except that long black whiskers adorn the animal’s -cheeks. The hair on the forearms is directed towards the elbows, -as is the case with all the anthropoid apes, and with man himself. -This hair forms, where it meets the hair from the upper arm, a small -ruff about the elbow joint. The chimpanzees live in society in the -woods, constructing huts from the branches and foliage of trees to -protect themselves against the sun and heavy rains. It is said by some -travellers that the chimpanzee walks upright in its native woods, but -this is doubtful; though certainly the formation of the toes better -fits them to stand upright than either the gorilla or the orang. They -arm themselves with clubs, and unite to defend themselves against the -attacks of wild beasts, “compelling,” it is said, “even the elephant -himself to abandon the districts in which they reside.” We learn that -“it is dangerous for men to enter their forests, unless in companies -and well armed; women in particular are often said to be carried away -by these animals, and one negress is reported to have lived among them -for the space of three years, during which time they treated her with -uniform kindness, but always prevented any attempt on her part to -escape. When the negroes leave a fire in the woods, it is said that -the chimpanzees will gather round and warm themselves at the blaze, -but they have not sufficient intelligence to keep it alive by fresh -supplies of fuel.” - -The orang-outang inhabits Borneo, Java, Sumatra, and other islands -of the Indian coast. He attains a greater height than the gorilla, -but, though very powerful and active, would probably not be a match -for the gorilla in a single combat. His arms are by comparison as -well as actually much longer. Whereas the gorilla’s reach only to the -knees, the arms of the orang-outang almost reach the ground when the -animal is standing upright. The orang does not often assume an upright -attitude, however. “It seldom attempts to walk on the hind feet alone, -and when it does the hands are invariably employed for the purpose of -steadying its tottering equilibrium, touching the ground lightly on -each side as it proceeds, and by this means recovering the lost balance -of the body.” The gorilla uses his hands differently. He can scarcely -be said to walk on all-fours, because he does not place the inside of -the hand on the ground, but walks on the knuckles, evidently trying -to keep the fore part of the body as high as possible. “The muzzle is -somewhat long, the mouth ill-shaped, the lips thin and protuberant; the -ears are very small, the chin scarcely recognizable, and the nose only -to be recognized by the nostrils. The face, ears, and inside of the -hands of the orang are naked and of a brick-red colour; the fore parts -are also but thinly covered with hair; but the head, shoulders, back, -and extremities are thickly clothed with long hair of dark wine-red -colour, directed forwards on the crown of the head and upwards towards -the elbows on the forearms.” - -The orang-outang changes remarkably in character and appearance as he -approaches full growth. “Though exhibiting in early youth a rotundity -of the cranium and a height of forehead altogether peculiar, and -accompanied at the same time with a gentleness of disposition and -a gravity of manners which contrast strongly with the petulant and -irascible temper of the lower orders of quadrumanous mammals, the -orang-outang in its adult state is even remarkable for the flatness -of its retiring forehead, the great development of the superorbital -and occipital crests, the prominence of its jaws, the remarkable -size of its canine teeth, and the whole form of the skull, which -from the globular shape of the human head, as in the young specimen, -assumes all the forms and characters belonging to that of a large -carnivorous animal. The extraordinary contrasts thus presented in the -form of the skull at different epochs of the same animal’s life were -long considered as the characters of distinct species; nor was it -till intermediate forms were obtained, exhibiting in some degree the -peculiarities of both extremes, that they were finally recognized as -distinguishing different periods of growth only.” - -Unlike the gorilla, which attacks man with peculiar malignity, and the -chimpanzee, which when in large troops assails those who approach its -retreats, the orang, even in its adult state, seems not to be dangerous -unless attacked. Even then he does not always show great ferocity. -The two following anecdotes illustrate well its character. The first -is from the pen of Dr. Abel Clarke (fifth volume of the “Asiatic -Researches”); the other is from Wallace’s interesting work, “The Malay -Archipelago.” An orang-outang fully seven feet high was discovered -by the company of a merchant ship, at a place called Ramboon, on the -north-west coast of Sumatra, on a spot where there were few trees -and little cultivated ground. “It was evident that he had come from -a distance, for his legs were covered with mud up to the knees, and -the natives were unacquainted with him. On the approach of the boat’s -crew he came down from the tree in which he was discovered, and made -for a clump at some distance; exhibiting, as he moved, the appearance -of a tall man-like figure, covered with shining brown hair, walking -erect, with a waddling gait, but sometimes accelerating his motion -with his hands, and occasionally impelling himself forward with the -bough of a tree. His motion on the ground was evidently not his natural -mode of progression, for, even when assisted by his hands and the -bough, it was slow and vacillating; it was necessary to see him among -the trees to estimate his strength and agility. On being driven to a -small clump, he gained by one spring a very lofty branch and bounded -from one branch to another with the swiftness of a common monkey, his -progress being as rapid as that of a swift horse. After receiving -five balls his exertions relaxed, and, reclining exhausted against a -branch, he vomited a quantity of blood. The ammunition of the hunters -being by this time exhausted, they were obliged to fell the tree -in order to obtain him; but what was their surprise to see him, as -the tree was falling, effect his retreat to another, with seemingly -undiminished vigour! In fact, they were obliged to cut down all the -trees before they could force him to combat his enemies on the ground, -and when finally overpowered by numbers, and nearly in a dying state, -he seized a spear made of supple wood, which would have withstood the -strength of the stoutest man, and broke it like a reed. It was stated, -by those who aided in his death, that the human-like expression of -his countenance and his piteous manner of placing his hands over his -wounds, distressed their feelings so as almost to make them question -the nature of the act they were committing. He was seven feet high, -with a broad expanded chest and narrow waist. His chin was fringed -with a beard that curled neatly on each side, and formed an ornamental -rather than a frightful appendage to his visage. His arms were long -even in proportion to his height, but his legs were much shorter. Upon -the whole, he was a wonderful beast to behold, and there was more about -him to excite amazement than fear. His hair was smooth and glossy, and -his whole appearance showed him to be in the full vigour of his youth -and strength.” On the whole, the narrative seems to suggest a remark -similar to one applied by Washington Irving to the followers of Ojeda -and their treatment of the (so-called) Indians of South America, “we -confess we feel a momentary doubt whether the arbitrary appellation of -‘brute’ is always applied to the right party.” - -The other story also presents man as at least as brutal as the orang -concerned in the event. “A few miles down the river,” says Wallace, -“there is a Dyak house, and the inhabitants saw a large orang feeding -on the young shoots of a palm by the river-side. On being alarmed he -retreated towards the jungle which was close by, and a number of the -men, armed with spears and choppers, ran out to intercept him. The man -who was in front tried to run his spear through the animal’s body; but -the orang seized it in his hands, and in an instant got hold of the -man’s arm, which he seized in his mouth, making his teeth meet in -the flesh above the elbow, which he tore and lacerated in a dreadful -manner. Had not the others been close behind, the man would have been -more seriously injured, if not killed, as he was quite powerless; but -they soon destroyed the creature with their spears and choppers. The -man remained ill for a long time, and never fully recovered the use of -his arm.” - -The term gibbon includes several varieties of tail-less, long-armed, -catarhine apes. The largest variety, called the siamang, need alone be -described here. - -The siamang inhabits Sumatra. It presents several points of resemblance -to the orang-outang, but is also in several respects strongly -distinguished from that animal. The arms are longer even than the -orang’s, and the peculiar use which the orang makes of his long arms -is more strikingly shown in the progression of the long-armed siamang, -for the body inclining slightly forward, when the animal is on level -ground the long arms are used somewhat like crutches, and they advance -by jerks resembling the hobbling of a lame man whom fear compels -to make an extraordinary effort. The skull is small, and much more -depressed than that of the orang or chimpanzee. The face is naked and -black, straggling red hairs marking the eyebrows. The eyes are deeply -sunk, a peculiarity which, by the way, seems characteristic of arboreal -creatures generally;[37] the nose broad and flat, with wide-open -nostrils; the cheeks sunk under high cheekbones; the chin almost -rudimentary. “The hair over the whole body is thick, long, and of a -glossy black colour, much closer on the shoulders, back, and limbs than -on the belly, which, particularly in the females, is nearly naked. The -ears are entirely concealed by the hair of the head; they are naked, -and, like all the other naked parts, of a deep black colour. Beneath -the chin there is a large, bare sac, of a lax and oily appearance, -which is distended with air when the animal cries, and in that state -resembles an enormous goitre. It is similar to that possessed by -the orang-outang, and undoubtedly assists in swelling the volume of -the voice, and producing those astounding cries which, according to -Duvancelle’s account, may be heard at the distance of several miles.” -This, however, may be doubted, for M. Duvancelle himself remarks of the -wouwou, that, “though deprived of the guttural sac so remarkable in the -siamang, its cry is very nearly the same; so that it would appear that -this organ does not produce the effect of increasing the sound usually -attributed to it, or else that it must be replaced in the wouwou by -some analogous formation.” - -The habits of the siamang are interesting, especially in their bearing -on the relationship between the various orders of anthropoid apes -and man; for, though the gibbon is unquestionably the lowest of the -four orders of the anthropoid apes in intelligence, it possesses -some characteristics which bring it nearer to man (so far as they -are concerned) than any of its congeners. The chief authorities -respecting the ways of the siamang are the French naturalists Diard and -Duvancelle, and the late Sir Stamford Raffles. - -The siamangs generally assemble in large troops, “conducted, it is -said, by a chief, whom the Malays believe to be invulnerable, probably -because he is more agile, powerful, and difficult to capture than the -rest.” “Thus united,” proceeds M. Duvancelle (in a letter addressed -to Cuvier), “the siamangs salute the rising and the setting sun with -the most terrific cries” (like sun-worshippers), “which may be heard -at the distance of many miles, and which, when near, stun when they -do not frighten. This is the morning call of the mountain Malays; but -to the inhabitants of the town, who are unaccustomed to it, it is an -unsupportable annoyance. By way of compensation, the siamangs keep -a profound silence during the day, unless when interrupted in their -repose or their sleep. They are slow and heavy in their gait, wanting -confidence when they climb and agility when they leap, so that they may -be easily caught when they can be surprised. But nature, in depriving -them of the means of readily escaping danger, has endowed them with a -vigilance which rarely fails them; and if they hear a noise which is -unusual to them, even at the distance of a mile, fright seizes them and -they immediately take flight. When surprised on the ground, however, -they may be captured without resistance, either overwhelmed with fear -or conscious of their weakness and the impossibility of escaping. At -first, indeed, they endeavour to avoid their pursuers by flight, and -it is then that their want of skill in this exercise becomes most -apparent.” - -“However numerous the troop may be, if one is wounded it is immediately -abandoned by the rest, unless, indeed, it happen to be a young one. -Then the mother, who either carries it or follows close behind, stops, -falls with it, and, uttering the most frightful cries, precipitates -herself upon the common enemy with open mouth and arms extended. But it -is manifest that these animals are not made for combat; they neither -know how to deal nor to shun a blow. Nor is their maternal affection -displayed only in moments of danger. The care which the females bestow -upon their offspring is so tender and even refined, that one would be -almost tempted to attribute the sentiment to a rational rather than -an instinctive process. It is a curious and interesting spectacle, -which a little precaution has sometimes enabled me to witness, to see -these females carry their young to the river, wash their faces in -spite of their outcries, wipe and dry them, and altogether bestow -upon their cleanliness a time and attention that in many cases the -children of our own species might well envy. The Malays related a -fact to me, which I doubted at first, but which I consider to be in -a great measure confirmed by my own subsequent observations. It is -that the young siamangs, whilst yet too weak to go alone, are always -carried by individuals of their own sex, by their fathers if they are -males, and by their mothers if females. I have also been assured that -these animals frequently become the prey of the tiger, from the same -species of fascination which serpents are said to exercise over birds, -squirrels, and other small animals. Servitude, however long, seems -to have no effect in modifying the characteristic defects of this -ape—his stupidity, sluggishness, and awkwardness. It is true that a -few days suffice to make him as gentle and contented as he was before -wild and distrustful; but, constitutionally timid, he never acquires -the familiarity of other apes, and even his submission appears to be -rather the result of extreme apathy than of any degree of confidence or -affection. He is almost equally insensible to good or bad treatment; -gratitude and revenge are equally strange to him.” - -We have next to consider certain points connected with the theory of -the relationship between man and the anthropoid apes. It is hardly -necessary for me to say, perhaps, that in thus dealing with a subject -requiring for its independent investigation the life-long study of -departments of science which are outside those in which I have taken -special interest, I am not pretending to advance my opinion as of -weight in matters as yet undetermined by zoologists. But it has always -seemed to me, that when those who have made special study of a subject -collect and publish the result of their researches, and a body of -evidence is thus made available for the general body scientific, the -facts can be advantageously considered by students of other branches -of science, so only that, in leaving for a while their own subject, -they do not depart from the true scientific method, and that they are -specially careful to distinguish what has been really ascertained from -what is only surmised with a greater or less degree of probability. - -In the first place, then, I would call attention to some very common -mistakes respecting the Darwinian theory of the Descent of Man. I -do not refer here to ordinary misconceptions respecting the theory -of natural selection. To say the truth, those who have not passed -beyond _this_ stage of error,—those who still confound the theory of -natural selection with the Lamarckian and other theories (or rather -hypotheses[38]) of evolution,—are not as yet in a position to deal -with our present subject, and may be left out of consideration. - -The errors to which I refer are in the main included in the following -statement. It is supposed by many, perhaps by most, that according to -Darwin man is descended from one or other of the races of anthropoid -apes; and that the various orders and sub-orders of apes and monkeys -at present existing can be arranged in a series gradually approaching -more and more nearly to man, and indicating the various steps (or some -of them, for gaps exist in the series) by which man was developed. -Nothing can be plainer, however, than Darwin’s contradiction of this -genealogy for the human races. Not only does he not for a moment -countenance the belief that the present races of monkeys and apes can -be arranged in a series gradually approximating more and more nearly to -man, not only does he reject the belief that man is descended from any -present existing anthropoid ape, but he even denies that the progenitor -of man resembled any known ape. “We must not fall into the error of -supposing,” he says, “that the early progenitor of the whole simian -stock, including man, was identical with, or even closely resembled, -any existing ape or monkey.” - -It appears to me, though it may seem somewhat bold to express this -opinion of the views of a naturalist so deservedly eminent as Mr. -Mivart, that in his interesting little treatise, “Man and Apes,”—a -treatise which may be described as opposed to Darwin’s special views -but not generally opposed to the theory of evolution,—he misapprehends -Darwin’s position in this respect. For he arrives at the conclusion -that if the Darwinian theory is sound, then “low down” (_i.e._, far -remote) “in the scale of Primates” (tri-syllabic) “was an ancestral -form so like man that it might well be called an _homunculus_; and we -have the virtual pre-existence of man’s body supposed, in order to -account for the actual first appearance of that body as we know it—a -supposition manifestly absurd if put forward as an explanation.”[39] - -How, then, according to the Darwinian theory, is man related to the -monkey? The answer to this question is simply that the relationship -is the same in kind, though not the same in degree, as that by which -the most perfect Caucasian race is related to the lowest race of -Australian, or Papuan, or Bosjesman savages. No one supposes that one -of these races of savages could by any process of evolution, however -long-continued, be developed into a race resembling the Caucasian -in bodily and mental attributes. Nor does any one suppose that the -savage progenitor of the Caucasian races was identical with, or even -closely resembled, any existing race of savages. Yet we recognize in -the lowest forms of savage man our blood relations. In other words, it -is generally believed that if our genealogy, and that of any existing -race of savages, could be traced back through all its reticulations, -we should at length reach a race whose blood we share with that race. -It is also generally believed (though for my own part I think the -logical consequences of the principle underlying all theories of -evolution is in reality opposed to the belief) that, by tracing the -genealogical reticulations still further back, we should at length -arrive at a single race from which all the present races of man and no -other animals have descended. The Darwinian faith with respect to men -and monkeys is precisely analogous. It is believed that the genealogy -of every existent race of monkeys, if traced back, would lead us to -a race whose blood we share with that race of monkeys; and—which is -at once a wider and a more precise proposition—that, as Darwin puts -it, “the two main divisions of the Simiadæ, namely, the catarhine -and platyrhine monkeys, with their sub-groups, have all proceeded -from some one extremely ancient progenitor.” This proposition is -manifestly wider. I call it also more precise, because it implies, and -is evidently intended by Darwin to signify, that from that extremely -ancient progenitor no race outside the two great orders of Simiadæ have -even partially _descended_, though other races share with the Simiadæ -descent from some still more remote race of progenitors. - -This latter point, however, is not related specially to the common -errors respecting the Darwinian theory which I have indicated above, -except in so far as it is a detail of the actual Darwinian theory. -I would, in passing, point out that, like the detail referred to in -connection with the relationship of the various races of man, this -one is not logically deducible from the theory of evolution. In fact, -I have sometimes thought that the principal difficulties of that -theory arise from this unnecessary and not logically sound doctrine. -I pointed out, rather more than three years ago, in an article “On -some of our Blood Relations,” in a weekly scientific journal, that the -analogy between the descent of races and the descent of individual -members of any race, requires us rather to believe that the remote -progenitor of the human race and the Simiadæ has had its share—though -a less share—in the generation of other races related to these in more -or less remote degrees. I may perhaps most conveniently present the -considerations on which I based this conclusion, by means of a somewhat -familiar illustration:— - -Let us take two persons, brother and sister (whom let us call the -pair A), as analogues of the human race. Then these two have four -great-grandparents on the father’s side, and four on the mother’s side. -All these may be regarded as equally related to the pair A. Now, let us -suppose that the descendants of the four families of great-grandparents -intermarry, no marriages being in any case made outside these families, -and that the descendants in the same generation as the pair A are -regarded as corresponding to the entire order of the Simiadæ, the -pair A representing, as already agreed, the race of man, and all -families outside the descendants of the four great-grandparental -families corresponding to orders of animals more distantly related -than the Simiadæ to man. Then we have what corresponds (so far as -our illustration is concerned) to Darwin’s views respecting man -and the Simiadæ, and animals lower in the scale of life. The first -cousins of the pair A may be taken as representing the anthropoid -apes; the second cousins as representing the lemurs or half-apes; the -third cousins as representing the platyrhine or American apes. The -entire family—including the pair A, representing man—is descended -also, in accordance with the Darwinian view, from a single family of -progenitors, no outside families sharing _descent_, though all share -_blood_, with that family. - -But manifestly, this is an entirely artificial and improbable -arrangement in the case of families. The eight grandparents _might_ -be so removed in circumstances from surrounding families—so much -superior to them, let us say—that neither they nor any of their -descendants would intermarry with these inferior families: and thus -none of their great-grandchildren would share descent from some other -stock contemporary with the great-grandparents; or—which is the same -thing, but seen in another light—none of the contemporaries of the -great-grandchildren would share descent from the eight grandparents. -But so complete a separation of the family from surrounding families -would be altogether exceptional and unlikely. For, even assuming the -eight families to be originally very markedly distinguished from all -surrounding families, yet families rise and fall, marry unequally, and -within the range of a few generations a wide disparity of blood and -condition appears among the descendants of any group of families. So -that, in point of fact, the relations assumed to subsist between man, -the Simiadæ, and lower animal forms, corresponds to an unusual and -improbable set of relations among families of several persons. Either, -then, the relations of families must be regarded as not truly analogous -to the relations of races, which no evolutionist would assert, or else -we must adopt a somewhat different view of the relationship between -man, the Simiadæ, and inferior animals. - -One other illustration may serve not only to make my argument clearer, -but also, by presenting an actual case, to enforce the conclusion to -which it points. - -We know that the various races of man are related together more or -less closely, that some are purer than others, and that one or two -claim almost absolute purity. Now, if we take one of these last, as, -for instance, the Jewish race, and trace the race backwards to its -origin, we find it, according to tradition, carried back to twelve -families, the twelve sons of Jacob and their respective wives. (We -cannot go further back because the wives of Jacob’s sons must be taken -into account, and they were not descended from Abraham or Isaac and -their wives only,—in fact, could not have been.) If the descendants -of those twelve families had never intermarried with outside families -in such sort that the descendants of such mixed families came to -be regarded as true Hebrews, we should have in the Hebrews a race -corresponding to the Simiadæ as regarded by Darwin, _i.e._, a race -entirely descended from one set of families, and so constituting, -in fact, a single family. But we know that, despite the objections -entertained by the Hebrews against the intermixture of their race with -other races, this did not happen. Not only did many of those regarded -as true Hebrews share descent from nations outside their own, but many -of those regarded as truly belonging to nations outside the Jewish race -shared descent from the twelve sons of Jacob. - -The case corresponding, then, to that of the purest of all human -races, and the case therefore most favourable to the view presented -by Darwin (though very far from essential to the Darwinian theory), -is simply this, that, in the first place, many animals regarded as -truly Simiadæ share descent from animals outside that family which -Darwin regards as the ape progenitor of man; and, in the second place, -many animals regarded as outside the Simiadæ share descent from that -ape-like progenitor. This involves the important inference that the -ape-like progenitor of man was not so markedly differentiated from -other families of animals then existing, that fertile intercourse -was impossible. A little consideration will show that this inference -accords well with, if it might not almost have been directly deduced -from, the Darwinian doctrine that all orders of mammals were, in -turn, descended from a still more remote progenitor race. The same -considerations may manifestly be applied also to that more remote -race, to the still more remote race from which all the vertebrates -have descended, and so on to the source itself from which all forms of -living creatures are supposed to have descended. A difficulty meets -us at that remotest end of the chain analogous to the difficulty of -understanding how life began at all; but we should profit little by -extending the inquiry to these difficulties, which remain, and are -likely long to remain, insuperable. - -So far, however, are the considerations above urged from introducing -any new or insuperable objection to the Darwinian theory, that, rightly -understood, they indicate the true answer to an objection which has -been urged by Mivart and others against the belief that man has -descended from some ape-like progenitor. - -Mivart shows that no existing ape or monkey approaches man more nearly -in all respects than other races, but that one resembles man more -closely in some respects, another in others, a third in yet others, -and so forth. “The ear lobule of the gorilla makes him our cousin,” -he says, “but his tongue is eloquent in his own dispraise.” If the -“bridging convolutions of the orang[’s brain] go to sustain his claim -to supremacy, they also go far to sustain a similar claim on the -part of the long-tailed thumbless spider-monkeys. If the obliquely -ridged teeth of _Simia_ and _Troglodytes_ (the chimpanzee) point to -community of origin, how can we deny a similar community of origin, as -thus estimated, to the howling monkeys and galagos? The liver of the -gibbons proclaims them almost human; that of the gorilla declares him -comparatively brutal. The lower American apes meet us with what seems -the ‘front of Jove himself,’ compared with the gigantic but low-browed -denizens of tropical Western Africa.” - -He concludes that the existence of these wide-spread signs of affinity -and the associated signs of divergence, disprove the theory that the -structural characters existing in the human frame have had their origin -in the influence of inheritance and “natural selection.” “In the words -of the illustrious Dutch naturalists, Messrs. Schroeder, Van der Kolk -and Vrolik,” he says, “the lines of affinity existing between different -Primates construct rather a network than a ladder. It is indeed a -tangled web, the meshes of which no naturalist has as yet unravelled -by the aid of natural selection. Nay, more, these complex affinities -form such a net for the use of the teleological _retiarius_ as it -will be difficult for his Lucretian antagonist to evade, even with the -countless turns and doublings of Darwinian evolutions.” - -It appears to me that when we observe the analogy between the -relationships of individuals, families, and races of man, and the -relationships of the various species of animals, the difficulty -indicated by Mr. Mivart disappears. Take, for instance, the case -of the eight allied families above considered. Suppose, instead of -the continual intermarriages before imagined—an exceptional order -of events, be it remembered—that the more usual order of things -prevails, viz., that alliances take place with other families. For -simplicity, however, imagine that each married pair has two children, -male and female, and that each person marries once and only once. Then -it will be found that the pair A have ten families of cousins, two -first-cousin families, and eight second-cousin families; these are all -the families which share descent from the eight great-grandparents of -the pair. (To have third-cousin families we should have to go back to -the fourth generation.) Thus there are eleven families in all. Now, -in the case first imagined of constant intermarrying, there would -still have been eleven families, but they would all have descended -from eight great-grandparents, and we should then expect to find -among the eleven families various combinations, so to speak, of the -special characteristics of the eight families from which they had -descended. On the other hand, eleven families, in _no_ way connected, -have descended from eighty-eight great-grandparents, and would -present a corresponding variety of characteristics. But in the case -actually supposed, in which the eleven families are so related that -each one (for what applies to the pair A applies to the others) has -two first-cousin families, and eight second-cousin families, it will -be found that instead of 88 they have only 56 great-grandparents, -or ancestors, in the third generation above them. The two families -related as first cousins to the pair A have, like these, eight -great-grandparents, four out of these eight for one family, being the -four grandparents of the father of the pair A, the other four being -outsiders; while four of the eight great-grandparents of the other -family of first cousins are the four grandparents of the mother of the -pair A, the other four being outsiders. The other eight families each -have eight great-grandparents; two of the families having among their -great-grandparents the parents of one of the grandfathers of the pair -A, but no other great-grandparent in common with the pair A; other two -of the eight families having among their great-grandparents the parents -of the other grandfather of the pair A; other two having among their -great-grandparents the parents of one of the grandmothers of the pair -A; the remaining two families having among their great-grandparents the -parents of the other grandmother of the pair A; while in all cases the -six remaining great-grandparents of each family are outsiders, in no -way related, on our assumption, either to the eight great-grandparents -of the pair A or to each other, except as connected in pairs by -marriage. - -Now manifestly in such a case, which, save for the symmetry introduced -to simplify its details, represents fairly the usual relationships -between any family, its first cousins, and its second cousins, we -should not expect to find any one of the ten other families resembling -the pair A more closely in _all_ respects than would any other of -the ten. The two first-cousin families would _on the whole_ resemble -the pair A more nearly than would any of the other eight, but we -should expect to find _some_ features or circumstances in which one -or other or all of the second-cousin families would show a closer -resemblance to one or other or both of the pair A. This is found often, -perhaps generally, to be the case, even as respects the ordinary -characteristics in which resemblance is looked for, as complexion, -height, features, manner, disposition, and so forth. Much more would -it be recognized, if such close investigation could be made among the -various families as the naturalist can make into the characteristics -of men and animals. The fact, then, that features of resemblance to -man are found, not all in one order of the Simiadæ, but scattered among -the various orders, is perfectly analogous with the laws of resemblance -recognized among the various members of more or less closely related -families. - -The same result follows if we consider the analogy between various -different species of animals on the one hand and between various races -of the human family on the other. No one thinks of urging against the -ordinary theory that men form only a single species, the objection that -none of the other families of the human race can be regarded as the -progenitor of the Caucasian family, seeing that though the Mongolian -type is nearer in some respects, the Ethiopian is nearer in others, -the American in others, the Malay in yet others. We find in this the -perfect analogue of what is recognized in the relationships between -families all belonging to one nation, or even to one small branch of -a nation. Is it not reasonable, then, to find in the corresponding -features of scattered resemblance observed among the various branches -of the great Simian family, not the objection which Mivart finds -against the theory of relationship, but rather what should be expected -if that theory is sound, and therefore, _pro tanto_, a confirmation of -the theory? - -But now, in conclusion, let us briefly consider the great difficulty -of the theory that man is descended from some ape-like, arboreal, -speechless animal,—the difficulty of bridging over the wide gap which -confessedly separates the lowest race of savages from the highest -existing race of apes. After all that has been done to diminish the -difficulty, it remains a very great one. It is quite true that what -is going on at this present time shows how the gap has been widened, -and therefore indicates how it may once have been comparatively small. -The more savage races of man are gradually disappearing on the one -hand, the most man-like apes are being destroyed on the other,—so -that on both sides of the great gap a widening process is at work. Ten -thousand years hence the least civilized human race will probably be -little inferior to the average Caucasian races of the present day, -the most civilized being far in advance of the most advanced European -races of our time. On the other hand, the gorilla, the chimpanzee, the -orang-outang, and the gibbon will probably be extinct or nearly so. -True, the men of those days will probably have very exact records of -the characteristics not only of the present savage races of man, but of -the present races of apes. Nay, they will probably know of intermediate -races, long since extinct even now, whose fossil remains geologists -hope to discover before long as they have already discovered the -remains of an ape as large as man (the _Dryopithecus_) which existed -in Europe during the Miocene period;[40] and more recently the remains -of a race of monkeys akin to Macacus, which once inhabited Attica. But -although our remote descendants will thus possess means which we do not -possess of bridging the gap between the highest races of apes and the -lowest races of man, the gap will nevertheless be wider in their time. -And tracing backwards the process, which, thus traced forward, shows a -widened gap, we see that once the gap must have been much narrower than -it is. Lower races of man than any now known once existed on the earth, -and also races of apes nearer akin to man than any now existing, even -if the present races of apes are not the degraded descendants of races -which, living under more favourable conditions, were better developed -after their kind than the gorilla, chimpanzee, orang, and gibbon of the -present time. - -It may be, indeed, that in the consideration last suggested we may find -some assistance in dealing with our difficult problem. It is commonly -assumed that the man-like apes are the most advanced members of the -Simian family save man alone, and so far as their present condition is -concerned this may be true. But it is not necessarily the case that -the anthropoid apes have advanced to their present condition. Judging -from the appearance of the young of these races, we may infer with some -degree of probability that these apes are the degraded representatives -of more intelligent and less savage creatures. Whereas the young of -man is decidedly more savage in character than the well-nurtured and -carefully trained adult, the young of apes are decidedly less savage -than the adult. The same reasoning which leads us to regard the -wildness, the natural cruelty, the destructiveness, the love of noise, -and many other little ways of young children, as reminders of a more or -less remote savage ancestry, should lead us to regard the comparative -tameness and quiet of the young gorilla, for example, as evidence that -in remote times the progenitors of the race were not so wild and fierce -as the present race of gorillas. - -But even when all such considerations, whether based on the known or -the possible, have been taken into account, the gap between the lowest -savage and the highest ape is not easily bridged. It is easier to see -how man _may_ have developed from an arboreal, unspeaking animal to his -present state, than to ascertain how any part of the development was -actually effected; in other words, it is easier to suggest a general -hypothesis than to establish an even partial theory. - -That the progenitor of man was arboreal in his habits seems altogether -probable. Darwin recognizes in the arrangement of the hair on the human -forearm the strongest evidence on this point, so far as the actual -body of man is concerned; the remaining and perhaps stronger evidence -being derived from appearances recognized in the unborn child. He, -who usually seems as though he could overlook nothing, seems to me to -have overlooked a peculiarity which is even more strikingly suggestive -of original arboreal habits. There is one set of muscles, and, so far -as I know, one only, which the infant uses freely, while the adult -scarcely uses them at all. I mean the muscles which separate the toes, -and those, especially, which work the big toe. Very young children -not only move the toes apart, so that the great toe and the little toe -will be inclined to each other (in the plane of the sole) nearly ninety -degrees, but also distinctly clutch with the toes. The habit has no -relation to the child’s actual means of satisfying its wants. I have -often thought that the child’s manner of clutching with its fingers is -indicative of the former arboreal habits of the race, but it is not -difficult to explain the action otherwise. The clutching movement of -the toes, however, cannot be so explained. The child can neither bring -food to its mouth in this way nor save itself from falling; and as the -adult does not use the toes in this way the habit cannot be regarded -as the first imperfect effort towards movements subsequently useful. -In fact, the very circumstance that the movement is gradually disused -shows that it is useless to the human child in the present condition -of the race. In the very young gorilla the clutching motion of the -toes is scarcely more marked than it is in a very young child; only in -the gorilla the movement, being of use, is continued by the young, and -is developed into that effective clutch with the feet which has been -already described. Here we have another illustration of that divergency -which, rather than either simple descent or ascent, characterizes the -relationship between man and the anthropoid ape. In the growing gorilla -a habit is more and more freely used, which is more and more completely -given up by the child as he progresses towards maturity. - -Probably the arboreal progenitor of man was originally compelled to -abandon his arboreal habits by some slow change in the flora of his -habitat, resulting in the diminution and eventual disappearance of -trees suited for his movements. He would thus be compelled to adopt, at -first, some such course as the chimpanzee—making huts of such branches -and foliage as he could conveniently use for the purpose. The habit -of living in large companies would (as in the case of the chimpanzee) -become before long necessary, especially if the race or races thus -driven from their former abode in the trees were, like the gibbons, -unapt when alone both in attack and in defence. One can imagine how -the use of vocal signals of various kinds would be of service to the -members of these troops, not only in their excursions, but during the -work of erecting huts or defences against their enemies. If in two -generations the silent wild dog acquires, when brought into the company -of domestic dogs, no less than five distinct barking signals, we can -well believe that a race much superior in intelligence, and forced -by necessity to associate in large bodies, would—in many hundreds -of generations, perhaps—acquire a great number of vocal symbols. -These at first would express various emotions, as of affection, fear, -anxiety, sympathy, and so forth. Other signals would be used to -indicate the approach of enemies, or as battle-cries. I can see no -reason why gradually the use of particular vocal signs to indicate -various objects, animate or inanimate, and various actions, should -not follow after a while. And though the possession and use of many, -even of many hundreds, of such signs would be very far from even the -most imperfect of the languages now employed by savage races, one can -perceive the possibility—which is all that at present we can expect -to recognize—that out of such systems of vocal signalling a form of -language might arise, which, undergoing slow and gradual development, -should, in the course of many generations, approach in character -the language of the lowest savage races. That from such a beginning -language should attain its higher and highest developments is not more -wonderful in kind, though much more wonderful, perhaps, in degree, -than that from the first imperfect methods of printing should have -arisen the highest known developments of the typographic art. The -real difficulty lies in conceiving how mere vocal signalling became -developed into what can properly be regarded as spoken language. - -Of the difficulties related to the origin of, or rather the development -of, man’s moral consciousness, space will not permit me to speak, even -though there were much to be said beyond the admission that these -difficulties have not as yet been overcome. It must be remembered, -however, that races of men still exist whose moral consciousness can -hardly be regarded as very fully developed. Not only so, but, through -a form of reversion to savage types, the highest and most cultivated -races of man bring forth from time to time (as our police reports too -plainly testify) beings utterly savage, brutal, and even (“which is -else”) bestial. Nay, the man is fortunate who has never had occasion -to control innate tendencies to evil which are at least strongly -significant of the origin of our race. To most minds it must be -pleasanter as certainly it seems more reasonable, to believe that the -evil tendencies of our race are manifestations of qualities undergoing -gradual extinction, than to regard them as the consequences of one -past offence, and so to have no reason for trusting in their gradual -eradication hereafter. But, as Darwin says, in the true scientific -spirit, “We are not here concerned with hopes or fears, only with -the truth as far as our reason allows us to discover it. We must -acknowledge that man, with all his noble qualities, with sympathy which -feels for the most debased, with benevolence which extends not only -to other men but to the humblest living creature, with his God-like -intellect which has penetrated into the movements and constitution of -the solar system,—with all these exalted powers, man still bears in -his bodily frame the indelible stamp of his lowly origin.” As it seems -to me, man’s moral nature teaches the same lesson with equal, if not -greater, significance. - - - - -_THE USE AND ABUSE OF FOOD._ - - -Francis Bacon has laid it down as an axiom that experiment is the -foundation of all real progress in knowledge. “Man,” he said, “as the -minister and interpreter of nature, does and understands as much as -his observations on the order of nature permit him, and neither knows -nor is capable of more.”[41] It would seem, then, as if there could be -no subject on which man should be better informed than on the value -of various articles of food, and the quantity in which each should -be used. On most branches of experimental inquiry, a few men in each -age—perhaps but for a few ages in succession—have pursued for a -longer or shorter portion of their life, a system of experiment and -observation. But on the subject of food or diet all men in all ages -have been practical experimenters, and not for a few years only, but -during their entire life. One would expect, then, that no questions -could be more decisively settled than those which relate to the use or -the abuse of food. Every one ought to know, it might be supposed, what -kinds of food are good for the health, in what quantity each should -be taken, what changes of diet tend to correct this or that kind of -ill-health, and how long each change should be continued. - -Unfortunately, as we know, this is far from being the case. We all -eat many things which are bad for us, and omit to eat many things -which would be good for us. We change our diet, too often, without -any consideration, or from false considerations, of the wants of the -body. When we have derived benefit from some change of diet, we are apt -to continue the new diet after the necessity for it has passed away. -As to quantity, also, we seldom follow well-judged rules. Some take -less nutriment (or less of some particular form of nutriment) than -is needed to supply the absolute requirements of the system; others -persistently overload the system, despite all the warnings which their -own experience and that of others should afford of the mischief likely -to follow that course. - -It is only of late years that systematic efforts have been made to -throw light on the subject of the proper use of food, to distinguish -between its various forms, and to analyze the special office of each -form. I propose to exhibit, in a popular manner, some of the more -important practical conclusions to which men of science have been led -by their investigations into these questions. - -The human body has been compared to a lamp in which a flame is burning. -In some respects the comparison is a most apt one, as we shall see -presently. But man does more than _live_; he _works_,—with his -brain or with his muscles. And therefore the human frame may be more -justly compared to a steam-engine than to the flame of a lamp. Of -mere life, the latter illustration is sufficiently apt, but it leaves -unillustrated man’s capacity for work; and since food is taken with -two principal objects—the maintenance of life and the renewal of -material used up in brain work and muscular work—we shall find that -the comparison of man to a machine affords a far better illustration -of our subject than the more common comparisons of the life of man -to a burning flame, and of food to the fuel which serves to maintain -combustion. - -There is, however, one class of food, and, perhaps, on the whole, the -most important, the operation of which is equally well illustrated by -either comparison. The sort of food to which I refer may be termed -_heat-maintaining_ food. I distinguish it thus from food which serves -other ends, but of course it is not to be understood that any article -of diet serves _solely_ the end of maintaining heat. Accordingly, we -find that heat-maintaining substance exists in nearly all the ordinary -articles of food. Of these there are two—sugar and fat—which may be -looked on as special “heat-givers.” Starch, also, which appears in all -vegetables, and thus comes to form a large proportion of our daily -food, is a heat-giver. In fact, this substance only enters the system -in the form of sugar, the saliva having the power of converting starch -(which is insoluble in water) into sugar, and thus rendering it soluble -and digestible. - -Starch, as I have said, appears in all vegetables. But it is found -more freely in some than in others. It constitutes nearly the whole -substance of arrowroot, sago, and tapioca, and appears more or less -freely in potatoes, rice, wheat, barley, and oats. In the process -of vegetation it is converted into sugar; and thus it happens that -vegetable diet—whether presenting starch in its natural form to -be converted into sugar by the consumer, or containing sugar which -has resulted from a process of change undergone by starch—is in -general heat-maintaining. Sugar is used as a convenient means of -maintaining the heat-supply; for in eating sugar we are saved the -trouble of converting starch into sugar. A love for sweet things is -the instinctive expression of the necessity for heat-maintaining -food. We see this liking strongly developed in children, whose rapid -growth is continually drawing upon their heat-supply. So far as adults -are concerned, the taste for sweet food is found to prevail more in -temperate than in tropical climes, as might be expected; but, contrary -to what we might at first expect, we do not find any increase in -the liking for sweet food in very cold climates. Another and a more -effective way of securing the required heat-supply prevails in such -countries. - -As starch is converted into sugar, so by a further process sugar is -converted into fat. It is by the conversion of sugar into fat that -its heat-supplying power is made available. This conversion takes -place in the vegetable as well as in the animal system, and thus fat -appears in a variety of forms—as butter, suet, oil, and so forth. Now, -precisely as sugar is a more convenient heat-supplier than starch, -so fat exceeds sugar in its power of maintaining animal heat. It has -been calculated that one pound of fat—whether in the form of suet, -butter, or oil—will go as far towards the maintenance of animal heat -as two pounds of sugar, or as two pounds and a half of starch. Thus -it happens that in very cold countries there is developed a taste for -such articles of food as contain most fat, or even for pure fat and its -analogues—oil, butter, tallow, dripping, and other forms of _grease_. - -I have spoken of starch, sugar, and fat as heat-forming articles of -food; but I must note their influence in the development of muscles and -nerves. Without a certain proportion of fat in the food a wasting of -the tissues will always take place; for muscles and nerves cannot form -without fat. And conversely, the best remedy for wasting diseases is to -be found in the supply of some easily digestible form of fatty food. -Well-fatted meat, and especially meat in which the fat is to be seen -distributed through the flesh, may be taken under such circumstances. -Butter and salad oil are then also proper articles of food. Cream is -still better, and cream cheeses may be used with advantage. It is on -account of its heat-supplying and fat-forming qualities that cod-liver -oil has taken its place as one of the most valuable remedies for -scrofulous and consumptive patients. - -But it must be noted that the formation of fat is not the object with -which heat-supplying food is taken. It is an indication of derangement -of the system when heat-giving food is too readily converted into -fat. And in so far as this process of conversion takes place beyond -what is required for the formation of muscles and nerves, the body -suffers in the loss of its just proportion of heat-supply. Of course, -if too large an amount of heat-giving food is taken into the system, -we may expect that the surplus will be deposited in the form of -adipose tissue. The deposition of fat in such a case will be far less -injurious to the system than an excessive heat-supply would be. But -when only a just amount of heat-giving food is taken, and in place -of fulfilling its just office this food is converted into adipose -tissue, it becomes necessary to inquire into the cause of the mischief. -Technically, the evil may be described as resulting from the deficient -oxygenation of the heat-supplying food. This generally arises from -defective circulation, and may often be cured by a very moderate but -_systematic_ increase in the amount of daily exercise, or by the use -of the sponge-bath, or, lastly, by such changes in the dress—and -especially in the articles of attire worn next to the skin—as tend to -encourage a freer circulation of the blood. The tendency to accumulate -fat may sometimes be traced to the use of over-warm coverings at night, -and especially to the use of woollen night-clothes. By attending to -considerations of this sort, more readily and safely than by an undue -diminution of the amount of heat-supplying food, the tendency to -obesity may frequently be corrected. - -In warm weather we should diminish the supply of heat-giving food. In -such weather the system does not require the same daily addition to its -animal heat, and the excess is converted into fat. Experiments have -shown that despite the increased rate at which perspiration proceeds -during the summer months, men uniformly fed throughout the year -increase in weight in summer and lose weight in winter. - -So far as mere existence is concerned, heat-forming food may be looked -upon as the real fuel on which the lamp of life is sustained. But man, -considered as a working being, cannot exist without _energy-forming_ -food. All work, whether of the brain or of the limbs, involves the -exhaustion of nervous and muscular matter; and unless the exhausted -matter be renewed, the work must come to an end. The supply of -heat-giving food may be compared to the supply of fuel for the fire -of a steam-engine. By means of this supply the _fire_ is kept alive; -but if the fire have nothing to work upon, its energies are wasted or -used to the injury of the machine itself. The supply of water, and its -continual use (in the form of steam) in the propulsion of the engine, -are the processes corresponding to the continual exhaustion and renewal -of the muscles and nerves of the human frame. And the comparison may be -carried yet further. We see that in the case of the engine the amount -of smoke, or rather of carbonic acid, thrown out by the blast-pipe is -a measure of the vital energy (so to speak) within the engine; but the -amount of work done by the engine is measured rather by the quantity of -steam which is thrown out, because the elastic force of every particle -of steam has been exerted in the propulsion of the engine before being -thrown out through the blast-pipe. In a manner precisely corresponding -to this, the amount of carbonic acid gas exhaled by a man is a measure -of the rate at which mere existence is proceeding; but the amount of -work, mental or muscular, which the man achieves, is measured by the -amount of used-up brain-material and muscle-material which is daily -thrown off by the body. I shall presently show in what way this amount -is estimated. - -In the composition of the muscles there is a material called _fibrine_, -and in the composition of the nerves there is a material called -_albumen_. These are the substances[42] which are exhausted during -mental and bodily labour, and which have to be renewed if we are to -continue working with our head or with our hands. Nay more, life itself -involves work; the heart, the lungs, the liver, each internal organ of -the body, performs its share of work, just as a certain proportion of -the power of a steam-engine is expended in merely moving the machinery -which sets it in action. If the waste of material involved in this form -of work is not compensated by a continual and sufficient supply of -fibrine and albumen the result will be a gradual lowering of all the -powers of the system, until some one or other gives way,—the heart -ceases to beat, or the stomach to digest, or the liver to secrete -bile,—and so death ensues. - -The fibrine and albumen in the animal frame are derived exclusively -from vegetables. For although we seem to derive a portion of the -supply from animal food, yet the fibrine and albumen thus supplied -have been derived in the beginning from the vegetable kingdom. “It is -the peculiar property of the plant,” says Dr. Lankester, “to be able, -in the minute cells of which it is composed, to convert the carbonic -acid and ammonia which it gets from the atmosphere into fibrine -and albumen, and by easy chemical processes we can separate these -substances from our vegetable food. Wheat, barley, oats, rye, rice, all -contain fibrine, and some of them also albumen. Potatoes, cabbage, and -asparagus contain albumen. It is a well-ascertained fact that those -substances which contain most of these ‘nutritious secretions,’ as they -have been called, support life the longest.” They change little during -the process of digestion, entering the blood in a pure state, and being -directly employed to renew the nervous and muscular matter which has -been used up during work, either mental or muscular. Thus the supply -of these substances is continually being drawn upon. The carbon, which -forms their principal constituent, is converted into carbonic acid; -and the nitrogen, which forms about a sixth part of their substance, -re-appears in the nitrogen of urea, a substance which forms the -principal solid constituent of the matter daily thrown from the system -through the action of the kidneys. Thus the amount of urea which daily -passes from the body affords a measure of the work done during the day. -“This is not,” says Dr. Lankester, “the mere dream of the theorist; -it has been practically demonstrated that increased stress upon the -nervous system, viz., brain work, emotion, or excitement from disease, -increases the quantity of urea and the demand for nitrogenous food. In -the same manner the amount of urea is the representative of the amount -of muscular work done.” - -It has been calculated that the average amount of urea daily formed -in the body of a healthy man is about 470 grains. To supply this -daily consumption of nitrogenous matter, it is necessary that about -four ounces of flesh-forming substance should be consumed daily. -It is important, therefore, to inquire how this substance may be -obtained. The requisite quantity of albuminous and fibrinous matter -“is contained,” says Dr. Lankester, “in a pound of beef; in two pounds -of eggs; in two quarts of milk; in a pound of peas; in five pounds of -rice; in sixteen pounds of potatoes; in two pounds of Indian meal; -in a pound and a half of oatmeal; and in a pound and three-quarters -of flour.” A consideration of this list will show the importance of -attending to the quality as well as the quantity of our food. A man -of ordinary appetite might satisfy his hunger on potatoes or on rice, -without by any means supplying his system with a sufficient amount of -flesh-forming food. On the other hand, if a man were to live on bread -and beef alone, he would load his system with an amount of nitrogenous -food, although not taking what could be considered an excessive amount -of daily nourishment. We see, also, how it is possible to continually -vary the form in which we take the required supply of nitrogenous food, -without varying the amount of that supply from day to day. - -The supply itself should of course also vary from day to day as the -amount of daily work may vary. What would be ample for a person -performing a moderate amount of work would be insufficient for one -who underwent daily great bodily or mental exertions, and would be -too much for one who was taking holiday. It would appear, from the -researches of Dr. Haughton, that the amount of urea daily formed in -the body of a healthy man of average weight varies from 400 to 630 -grains. Of this weight it appears that 300 grains results from the -action of the internal organs. It would seem, therefore, that the -amount of flesh-forming food indicated in the preceding paragraph may -be diminished in the proportion of 47 to 40 in the case of a person -taking the minimum of exercise—that is, avoiding all movements save -those absolutely necessary for comfort or convenience. On the other -hand, that amount must be increased in the proportion of 74 to 63 in -the case of a person (of average weight) working up to his full powers. -It will be seen at once, therefore, that a hardworking man, whether -labourer or thinker, must make good flesh-forming food constitute a -considerable portion of his diet; otherwise he would require to take an -amount of food which would seriously interfere with his comfort and the -due action of his digestive organs. For instance, if he lived on rice -alone, he would require to ingest nearly seven pounds of food daily; if -on potatoes, he would require upwards of twenty-one pounds; whereas one -pound and a third of meat would suffice to supply the same amount of -flesh-forming food. - -Men who have to work, quickly find out what they require in the way of -food. The Irishman who, while doing little work, will live contentedly -on potatoes, asks for better flesh-forming food when engaged in heavy -labour. In fact, the employer of the working man, so far from feeling -aggrieved when his men require an improvement in their diet, either as -respects quality or quantity, ought to look on the want as evidence -that they are really working hard in his service, and also that they -have a capacity for continuous work. The man who lives on less than -the average share of flesh-forming food is doing less than an average -amount of work; the man who is unable to eat an average quantity of -flesh-forming food, is _unable_ to do an average amount of work. “‘On -what principle do you discharge your men?’ I once said,” relates Dr. -Lankester, “to a railway contractor. ‘Oh,’ he said, ‘it’s according to -their appetites.’ ‘But,’ I said, ‘how do you judge of that?’ ‘Why,’ -he said, ‘I send a clerk round when they are getting their dinners, -and those who can’t eat he marks with a bit of chalk, and we send them -about their business.’” - -At a lecture delivered at the Royal Museum of Physics and Natural -History at Florence, by Professor Mantegazza, a few years since, the -Professor dwelt on the insufficient food which Italians are in the -habit of taking, as among the most important causes of the weakness of -the nation. “Italians,” he said, “you should follow as closely as you -can the example of the English in your eating and in your drinking, -in the choice of flesh-meat (in tossing off bumpers of your rich -wines),[43] in the quality of your coffee, your tea, and your tobacco. -I give you this advice, dear countrymen, not only as a medical man, but -also as a patriot. It is quite evident, from the way millions of you -perform the process which you call eating and drinking, that you have -not the most elementary notions of the laws of physiology. You imagine -that you are living. You are barely prolonging existence on maccaroni -and water-melons. You neither know how to eat nor how to drink. You -have no muscular energy; and, therefore, you have no continuous mental -energy. The weakness of the individual, multiplied many millions of -times, results in the collective weakness of the nation. Hence results -insufficient work, and thence insufficient production. Thus the returns -of the tax-collector and the custom-house officer are scanty, and the -national exchequer suffers accordingly.” Nor is all this, strange as it -may sound, the mere gossip of the lecture-room. “The question of good -feeding,” says Dr. Lankester, “is one of national importance. It is -vain to expect either brain or muscles to do efficient work when they -are not provided with the proper material. Neither intellectual nor -physical work can be done without good food.” - -We have now considered the two principal forms of food, the -heat-forming—sometimes called the _amylaceous_—constituents, and -the flesh-forming or _nitrogenous_ constituents. But there are other -substances which, although forming a smaller proportion of the daily -food, are yet scarcely less important. Returning to our comparison of -the human system to a steam-engine—we have seen how the heat-forming -and flesh-forming constituents of food correspond to the supply of -fuel and water; but an engine would quickly fall into a useless state -if the wear and tear of the material of which it is constructed were -not attended to and repaired. Now, in the human frame there are -materials which are continually being used up, and which require to be -continually restored, if the system is to continue free from disease. -These materials are the mineral constituents of the system. Amongst -them we must include _water_, which composes a much larger portion of -our bodies than might be supposed. Seven-ninths of our weight consists -simply of water. Every day there is a loss of about one-thirtieth -part of this constituent of our system. The daily repair of this -important waste of material is not effected by imbibing a corresponding -supply of water. A large proportion of the weight of water daily lost -is renewed in the solid food. Many vegetables consist principally -of water. This is notably the case with potatoes. Where the water -supplied to a district is bad, so that little water is consumed by the -inhabitants—at least, without the addition of some other substance—it -becomes important to notice the varying proportion of water present -in different articles of food. As an instance of this, I may call -attention to a remarkable circumstance observed during the failure of -the potato crops in Ireland. Notwithstanding the great losses which -the people sustained at that time, it was noticed that the amount of -tea imported into Ireland exhibited a remarkable increase. This seemed -at first sight a somewhat perplexing phenomenon. The explanation was -recognized in the circumstance that the potato—a watery vegetable, as -we have said—no longer formed the chief portion of the people’s diet. -Thus the deficiency in the supply of water had to be made up by the -use of a larger quantity of fluid food; and as simple water was not -palatable to the people, they drank tea in much larger quantities than -they had been in the habit of taking before the famine. - -But we have to consider the other mineral constituents of the system. - -If I were to run through the list of all the minerals which exist -within the body, I should weary the patience of the reader, and -perhaps not add very much to the clearness of his ideas respecting the -constitution of the human frame. Let it suffice to state generally -that, according to the calculations of physiologists, a human body -weighing 154 pounds contains about 17½ pounds of mineral matter; and -that the most important mineral compounds existing within the body are -those which contain lime, soda, and potash. Without pretending to any -strictly scientific accuracy in the classification, we may say that -the lime is principally found in the bones, the soda in the blood, the -potash in the muscles; and according as one or other of these important -constituents is wanting in our food, so will the corresponding portions -of the frame be found to suffer. - -We have a familiar illustration of the effects of unduly diminishing -the supply of the mineral constituents of the body in the ravages -which scurvy has worked amongst the crews of ships which have remained -for a long period ill-supplied with fresh vegetables. Here it is -chiefly the want of potash in the food which causes the mischief. -An interesting instance of the rapid—almost startling—effects of -food containing potash, in the cure of men stricken by scurvy, is -related by Dana. The crew of a ship which had been several months at -sea, but was now nearing the land, were prostrated by the ravages of -scurvy. Nearly all seemed hopelessly ill. One young lad was apparently -dying, the livid spots which were spreading over his limbs seeming to -betoken his rapidly approaching end. At this moment a ship appeared -in view which had but lately left the land, and was laden with fresh -vegetables. Before long large quantities of the life-bearing food had -been transferred to the decks of the other ship. The instincts of life -taught the poor scurvy-stricken wretches to choose the vegetable which -of all others was best suited to supply the want under which their -frames were wasting. They also were led by the same truthful instincts -to prefer the raw to cooked vegetables. Thus the sick were to be seen -eating raw onions with a greater relish than the gourmand shows for -the most appetising viands. But the poor lad who was the worse of the -sufferers had already lost the power of eating; and it was without -a hope of saving his life that some of his companions squeezed the -juice of onions between his lips, already quivering with the tremor of -approaching death. He swallowed a few drops, and presently asked for -more. Shortly he began to revive, and to the amazement of all those -who had seen the state of prostration to which he had been reduced, he -regained in a few days his usual health and strength. - -The elements which we require in order to supply the daily waste of -the mineral constituents of the body are contained in greater or less -quantities in nearly all the articles which man uses for food. But it -may readily happen that, by adopting an ill-regulated diet, a man may -not take a sufficient quantity of these important elements. It must -also be noticed that articles of food, both animal and vegetable, may -be deprived of a large proportion of their mineral elements by boiling; -and if, as often happens, the water in which the food has been boiled -is thrown away, injurious effects can scarcely fail to result from -the free use of food which has lost so important a portion of its -constituent elements. Accordingly, when persons partake much of boiled -meat, they should either consume the broth with the meat, or use it -as soup on the alternate days. Vegetables steamed in small quantities -of water (this water being taken with them), also afford a valuable -addition to boiled meat. In fact, experience seems to have suggested -the advantage of mixing carrots, parsnips, turnips, and greens with -boiled meat; but unfortunately the addition is not always made in -a proper manner. If the vegetables are boiled separately in large -quantities of water, and served up after this water has been thrown -away, more harm than good is done by the addition; since the appetite -is satisfied with comparatively useless food, instead of being left -free to choose, as it might otherwise do, such forms of food as would -best supply the requirements of the system. Salads and uncooked fruits, -for instance, contain saline ingredients in large proportion, and -could be used advantageously after a meal of boiled meat. Potatoes are -likewise a valuable article of food on account of the mineral elements -contained in them. And there can be no doubt that the value of potatoes -as an article of food is largely increased when they are cooked in -their skins, after the Irish fashion. - -Lastly, we must consider those articles of food which promote the -natural vital changes, but do not themselves come to form part of the -frame, or, at least, not in any large proportion of their bulk. Such -are tea, coffee, and cocoa: alchoholic drinks; narcotics; and lastly, -spices and condiments. We may compare the use of these articles of food -to that of oil in lubricating various parts of a steam-engine. For, as -the oil neither forms part of the heat-supply nor of the force-supply -of the steam-engine, nor is used to replace the worn material of its -structure, yet serves to render the movements of the machine more -equable and effective, so the forms of food we are considering are -neither heat-producing nor flesh-forming, nor do they serve to replace, -to any great extent, the mineral constituents of the body, yet they -produce a sense of refreshment accompanied with renewed vigour. It is -difficult to determine in what precise way these effects are produced, -but no doubt can exist as to the fact that they are really attributable -to the forms of food to which we have assigned them. - -Tea, coffee, and cocoa owe their influence on the nervous system to -the presence of a substance which has received the various names of -_theine_, _caffeine_, and _theobromine_. It is identical in composition -with _piperine_, the most important ingredient in pepper. It may be -separated in the form of delicate white, silky crystals, which have a -bitter taste. In its concentrated form this substance is poisonous, and -to this circumstance must be ascribed the ill effects which follow -from the too free use of strong tea or coffee. However, the instances -of bad effects resulting from the use of “the cup which cheers but not -inebriates” are few and far between, while the benefits derived from -it are recognized by all. It has, indeed, been stated that no nation -which has begun to make use of tea, coffee, or cocoa, has ever given up -the practice; and no stronger evidence can be required of the value of -those articles of food. - -Of alcoholic liquors it is impossible to speak so favourably. They -are made use of, indeed, almost as extensively as tea or coffee; they -have been made the theme of the poet, and hailed as the emblems of -all that is genial and convivial. Yet there can be little doubt that, -when a balance is struck between the good and evil which have resulted -to man from their use, the latter is found largely to preponderate. -The consideration of these evils belongs, however, rather to the -moralist than to the physiologist. I have here simply to consider -alcoholic liquors as articles of food. There can be little doubt that, -when used with caution and judgment, they afford in certain cases an -important adjunct to those articles which are directly applied to -the reparation of bodily waste. Without absolutely nourishing the -frame, they ultimately lead to this end by encouraging the digestive -processes which result in the assimilation of nutritive articles of -food. But the quantity of alcohol necessary to effect this is far less -than is usually taken even by persons who are termed temperate. It is -also certain that hundreds make use of alcoholic liquors who have no -necessity for them, and who would be better without them. Those who -require them most are men who lead a studious sedentary life; and it -is such men, also, who suffer most from excess in the use of alcoholic -liquors. - -It remains that I should make a few remarks on mistakes respecting the -quantity of food. - -Some persons fall into the habit of taking an excessive quantity of -food, not from greediness, but from the idea that a large amount of -food is necessary for the maintenance of their strength. They thus -overtax the digestive organs, and not only fail of their purpose, but -weaken instead of strengthening the system. Especially serious is the -mistake often made by persons in delicate health of swallowing—no -other word can be used, for the digestive organs altogether refuse -to respond to the action of the mouth—large quantities of some -concentrated form of food, such as even the strongest stomach could -not deal with in that form. I knew a person who, though suffering -from weakness such as should have suggested the blandest and simplest -forms of food, adopted as a suitable breakfast mutton-chops and -bottled stout, arguing, when remonstrated with, that he required more -support than persons in stronger health. He was simply requiring his -weak digestive organs to accomplish work which would have taxed the -digestive energies of the most stalwart labourer working daily in the -open air for many hours. - -On the other hand, a too abstemious diet is as erroneous in principle -as a diet in excess of the natural requirements of the system. A -diet which is simply too abstemious is perhaps less dangerous than -persistent abstinence from the use of certain necessary forms of food. -Nature generally prevents us from injuring ourselves by unwisely -diminishing the quantity of food we take; but unfortunately she is not -always equally decided in her admonitions respecting the quality of -our food. A man may be injuring his health through a deficiency in the -amount either of the heat-forming or of the flesh-forming food which he -consumes, and yet know nothing of the origin of the mischief. It may -also be noted that systematic abstinence, either as respects quantity -or quality of food, is much more dangerous than an occasional fast. -Indeed, it is not generally injurious either to abstain for several -days from particular articles or forms of food, or to remain, for -several hours beyond the usual interval between meals, without food of -any sort. On the contrary, benefit often arises from each practice. The -Emperor Aurelian used to attribute the good health he enjoyed to his -habit of abstaining for a whole day, once a month, from food of all -sorts; and many have found the Lenten rules of abstinence beneficial. -As a rule, however, change of diet is a safer measure than periodical -fasting or abstinence from either heat-producing or flesh-forming -food. It must be noticed, in conclusion, that young persons ought not, -without medical advice, to fast or abstain for any length of time from -the more important forms of food, as serious mischief to the digestive -organs frequently follows from either course. - - - - -_OZONE._ - - -The singular gas termed ozone has attracted a large amount of attention -from chemists and meteorologists. The vague ideas which were formed as -to its nature when as yet it had been but newly discovered, have given -place gradually to more definite views; and though we cannot be said -to have thoroughly mastered all the difficulties which this strange -element presents, yet we know already much that is interesting and -instructive. - -Let us briefly consider the history of ozone. - -Nine years after Priestley had discovered oxygen, Van Marum, the -electrician, noticed that when electric sparks are taken through that -gas, a peculiar odour is evolved. Most people know this odour, since -it is always to be recognized in the neighbourhood of an electrical -machine in action. In reality, it indicates the presence of ozone in -the air. But for more than half a century after Van Marum had noticed -it, it was supposed to be the “smell of electricity.” - -In 1840, Schönbein began to inquire into the cause of this peculiar -odour. He presently found that it is due to some change in the oxygen; -and that it can be produced in many ways. Of these, the simplest, and, -in some respects, the most interesting, is the following:—“Take sticks -of common phosphorus, scrape them until they have a metallic lustre, -place them in this condition under a large bell-jar, and half-cover -them with water. The air in the bell-jar is soon charged with ozone, -and a large room can readily be supplied with ozonized air by this -process.” - -Schönbein set himself to inquire into the properties of this new gas, -and very interesting results rewarded his researches. It became quite -clear, to begin with, that whatever ozone may be, its properties are -perfectly distinct from those of oxygen. Its power of oxidizing or -rusting metals, for example, is much greater than that which oxygen -possesses. Many metals which oxygen will not oxidize at all, even -when they are at a high temperature, submit at once to the influence -of ozone. But the power of ozone on other substances than metals is -equally remarkable. Dr. Richardson states that, when air is so ozonized -as to be only respirable for a short time, its destructive power is -such that gutta-percha and india-rubber tubings are destroyed by merely -conveying it. - -The bleaching and disinfecting powers of ozone are very striking. -Schönbein was at first led to associate them with the qualities of -chlorine gas; but he soon found that they are perfectly distinct. - -It had not yet been shown whether ozone was a simple or a compound -gas. If simple, of course it could be but another form of oxygen. At -first, however, the chances seemed against this view; and there were -not wanting skilful chemists who asserted that ozone was a compound of -the oxygen of the air with the hydrogen which forms an element of the -aqueous vapour nearly always present in the atmosphere. - -It was important to set this question at rest. This was accomplished by -the labours of De la Rive and Marignac, who proved that ozone is simply -another form of oxygen. - -Here we touch on a difficult branch of modern chemical research. The -chemical elements being recognized as the simplest forms of matter, -it might be supposed that each element would be unchangeable in its -nature. That a compound should admit of change, is of course a thing to -be expected. If we decompose water, for instance, into its component -elements, oxygen and hydrogen, we may look on these gases as exhibiting -water to us in another form. And a hundred instances of the sort might -be adduced, in which, either by separating the elements of a compound, -or by re-arranging them, we obtain new forms of matter without any real -change of substance. But with an element, the case, one would suppose, -should be different. - -However, the physicist must take facts as he finds them; and amongst -the most thoroughly recognized chemical facts we have this one, that -elementary substances may assume different forms. Chemists call the -phenomenon allotropy. A well-known instance of allotropy is seen in -red phosphorus. Phosphorus is one of the chemical elements; and, as -every one knows, the form in which it is usually obtained is that of a -soft, yellow, semi-transparent solid, somewhat resembling bees’ wax in -consistence, poisonous, and readily taking fire. Red phosphorus is the -same element, yet differs wholly in its properties. It is a powder, it -does not readily take fire, and it is not poisonous. - -Ozone, then, is another form of oxygen. It is the only instance yet -discovered of gaseous allotropy. - -And now we have to deal with the difficult and still-vexed questions -of the way in which the change from oxygen is brought about, and the -actual distinction between the two forms of the same gas. Schönbein -held that common oxygen is produced by the combination of two special -forms of oxygen—the positive and the negative, or, as he called them, -ozone and antozone. He showed that, in certain conditions of the air, -the atmospheric oxygen exhibits qualities which are the direct reverse -of those which ozone exhibits, and are distinct from those of ordinary -oxygen. In oxygen thus negatived or antozonized, animals cannot live -any more than they can in nitrogen. The products of decomposition are -not only not destroyed as by ozone, but seem subject to preservative -influences, and speedily become singularly offensive; dead animal -matter rapidly putrefies, and wounds show a tendency to mortification. - -But the theory of positive and negative forms of oxygen, though still -held by a few physicists, has gradually given way before the advance -of new and sounder modes of inquiry. It has been proved, in the first -place, that ozone is denser than ordinary oxygen. The production of -ozone is always followed by a contraction of the gas’s volume, the -contraction being greater or less according to the amount of oxygen -which has been ozonized. Regularly as the observers—Messrs. Andrews -and Tait—converted a definite proportion of oxygen into ozone, the -corresponding contraction followed, and as regularly was the original -volume of the gas restored when, by the action of heat, the ozone was -reconverted into oxygen. - -And now a very singular experiment was made by the observers, with -results which proved utterly perplexing to them. Mercury has the power -of absorbing ozone; and the experimenters thought that if, after -producing a definite contraction by the formation of ozone, they could -absorb the ozone by means of mercury, the quantity of oxygen which -remained would serve to show them how much ozone had been formed, and -thence, of course, they could determine the density of ozone. - -Suppose, for instance, that we have one hundred cubic inches of oxygen, -and that by any process we reduce it to a combination of oxygen and -ozone occupying ninety-five cubic inches. Now, if the mercury absorbed -the ozone, and we found, say, that there only remained eighty-five -cubic inches of oxygen, we could reason in this way:—Ten cubic inches -were occupied by the ozone before the mercury absorbed it; but these -correspond to fifteen cubic inches of oxygen; hence, ozone must be -denser than oxygen in the proportion of fifteen to ten, or three to -two. And whatever result might have followed, a real absorption of the -ozone by the mercury would have satisfactorily solved the problem. - -But the result actually obtained did not admit of interpretation in -this way. The apparent absorption of the ozone by the mercury, that -is, the disappearance of the ozone from the mixture, was accompanied -by _no diminution of volume at all_. In other words, returning to -our illustrative case, after the absorption of the ozone from the -ninety-five cubic inches occupied by the mixture, there still remained -ninety-five cubic inches of oxygen; so that it seemed as though an -evanescent volume of ozone corresponded in weight to five cubic inches -of oxygen. This solution, of course, could not be admitted, since it -made the density of ozone _infinite_. - -The explanation of this perplexing experiment is full of interest and -instruction. The following is the account given by Mr. C. W. Heaton -(Professor of Chemistry at Charing Cross Hospital), slightly modified, -however, so that it may be more readily understood. - -Modern chemists adopt, as a convenient mode of representing the -phenomena which gases exhibit, the theory that every gas, whether -elementary or compound, consists of minute molecules. They suppose -that these molecules are of equal size, and are separated by equal -intervals so long as the gas remains unchanged in heat and density. -This view serves to account for the features of resemblance presented -by all gases. The features in which gases vary are accounted for by the -theory that the molecules are differently constituted. The molecules -are supposed to be clusters of atoms, and the qualities of a gas are -assumed to depend on the nature and arrangement of these ultimate -atoms. The molecules of some elements consist but of a single atom; -the molecules of others are formed by pairs of atoms; those of others -by triplets; and so on. Again, the molecules of compound gases are -supposed to consist of combinations of different _kinds_ of atoms. - -Now, Dr. Odling, to whom we owe the solution of the perplexing problem -described above, thus interpreted the observed phenomena. A molecule -of oxygen contains two atoms, one of ozone contains three, _and the -oxidizing power of ozone depends on the ease with which it parts with -its third atom of oxygen_. Thus, in the experiment which perplexed -Messrs. Andrews and Tait, the mercury only _seemed_ to absorb the -ozone; in reality it converted the ozone into oxygen by removing -its third atom. And now we see how to interpret such a result as we -considered in our illustrative case. Five cubic inches of oxygen -gave up their atoms, each atom combining with one of the remaining -oxygen doublets, so as to form a set of ozone triplets. Clearly, then, -fifteen cubic inches of oxygen were transformed into ozone. They now -occupied but ten cubic inches; so that the mixture, or ozonized oxygen, -contained eighty-five cubic inches of oxygen and ten of ozone. When the -mercury was introduced, it simply transformed all the ozone triplets -into oxygen doublets, by taking away the odd atom from each. It thus -left ten cubic inches of oxygen, which, with the remaining eighty-five, -constituted the ninety-five cubic inches observed to remain after the -supposed absorption of the ozone. - -It follows, of course, that ozone is half as heavy again as oxygen. - -But, as Mr. Heaton remarked, “this beautiful hypothesis, although -accounting perfectly for all known facts, was yet but a probability. -One link was lacking in the chain of evidence, and that link M. Soret -has supplied by a happily devised experiment.” Although mercury and -most substances are only capable of converting ozone into oxygen, oil -of turpentine has the power of absorbing ozone in its entirety. Thus, -when the experiment was repeated, with oil of turpentine in place of -the mercury, the ozone was absorbed, and the remaining oxygen, instead -of occupying ninety-five inches, occupied but eighty-five. After -this, no doubt could remain that Dr. Odling’s ingeniously conceived -hypothesis was the correct explanation of Messrs. Andrews and Tait’s -experiment. - -We recognize, then, in ozone a sort of concentrated oxygen, with this -peculiar property, that it possesses an extraordinary readiness to -part with its characteristic third atom, and so disappear _as ozone_, -two-thirds of its weight remaining as oxygen. - -It is to this peculiarity that ozone owes the properties which render -it so important to our welfare. We are indeed, as yet, in no position -to theorize respecting this element, our knowledge of its very -existence being so recent, and our information respecting its presence -in our atmosphere being of still more recent acquisition. - -Indeed, it is well remarked by Mr. Heaton, that we had, until quite -lately, no reason for confidently adopting Schönbein’s view that ozone -exists in our atmosphere. The test-papers which Schönbein made use of -turned blue under the influence of ozone, it is true, but they were -similarly influenced by other elements which are known to exist in our -atmosphere, and even the sun’s rays turned them blue. However, Dr. -Andrews has shown how the character of the air producing the change -can be further tested, so as to render it certain that ozone only has -been at work. If air which colours the test-papers be found to lose -the property after being heated, the change can only be due to ozone, -because nitrous and nitric acids (which have the power of colouring the -test-papers) would not be removed by the heat, whereas ozone is changed -by heat into oxygen. - -Once we are certain that ozone exists in the air, we must recognize -the fact that its presence cannot fail to have an important bearing on -our health and comfort; for ozone is an exceedingly active agent, and -cannot exist anywhere without setting busily to its own proper work. -What that work is, and whether it is beneficial or deleterious to -ourselves, remains to be considered. - -In the first place, ozone has immense power as a disinfectant. -It decomposes the products emanating from putrefying matter more -effectually than any other known element. Perhaps the most striking -proof ever given of its qualities in this respect is that afforded by -an experiment conducted by Dr. Richardson a few years ago. - -He placed a pint of blood taken from an ox in a large wide-mouthed -bottle. The blood had then coagulated, and it was left exposed to -the air until it had become entirely redissolved by the effects of -decomposition. At the end of a year the blood was put into a stoppered -bottle, and set aside for seven years. “The bottle was then taken from -its hiding-place,” says Dr. Richardson, “and an ounce of the blood was -withdrawn. The fluid was so offensive as to produce nausea when the -gases evolved from it were inhaled. It was subjected by Dr. Wood and -myself to a current of ozone. For a few minutes the odour of ozone -was destroyed by the odour of the gases from the blood; gradually the -offensive smell passed away; then the fluid mass became quite sweet, -and at last a faint odour of ozone was detected, whereupon the current -was stopped. The blood was thus entirely deodorized; but another and -most singular phenomenon was observed. The dead blood coagulated as the -products of decomposition were removed, and this so perfectly, that -from the new clot that was formed serum exuded. Before the experiment -commenced, I had predicted on theoretical grounds that secondary -coagulation would follow on purification; and this experiment, as well -as several others afterwards performed, verified the truth of the -prediction.” - -It will of course be understood that ozone, in thus acting as a -disinfectant, is transformed into oxygen. It parts with its third atom -as in the mercury experiment, and so loses its distinctive peculiarity. -Thus we might be led to anticipate the results which come next to be -considered. - -Ozone has certain work to do, and in doing that work is transmuted into -oxygen. It follows, then, that where there has been much work for ozone -to do, there we shall find little ozone left in the air. Hence, in -open spaces where there is little decomposing matter, we should expect -to find more ozone than in towns or cities. This accords with what is -actually observed. And not only is it found that country air contains -more ozone than town air, but it is found that air which has come from -the sea has more ozone than even the country air, while air in the -crowded parts of large cities has no ozone at all, nor has the air of -inhabited rooms. - -So far as we have gone, we might be disposed to speak unhesitatingly in -favour of the effects produced by ozone. We see it purifying the air -which would otherwise be loaded by the products of decomposing matter, -we find it present in the sea air and the country air which we know -to be so bracing and health-restoring after a long residence in town, -and we find it absent just in those places which we look upon as most -unhealthy. - -Again, we find further evidence of the good effects of ozone in -the fact that cholera and other epidemics never make their dreaded -appearance in the land when the air is well supplied with ozone—or -in what the meteorologists call “the ozone-periods.” And though we -cannot yet explain the circumstance quite satisfactorily, we yet seem -justified in ascribing to the purifying and disinfecting qualities of -ozone our freedom at those times from epidemics to which cleanliness -and good sanitary regulations are notedly inimical. - -But there is a reverse side to the picture. And as we described an -experiment illustrating the disinfecting qualities of ozone before -describing the good effects of the element, we shall describe an -experiment illustrating certain less pleasing qualities of ozone, -before discussing the deleterious influences which it seems capable of -exerting. - -Dr. Richardson found that when the air of a room was so loaded with -ozone as to be only respirable with difficulty, animals placed in the -room were affected in a very singular manner. “In the first place,” -he says, “all the symptoms of nasal catarrh and of irritation of the -mucous membranes of the nose, the mouth, and the throat were rapidly -induced. Then followed free secretion of saliva and profuse action of -the skin—perspiration. The breathing was greatly quickened, and the -action of the heart increased in proportion.” When the animals were -suffered to remain yet longer within the room, congestion of the lungs -followed, and the disease called by physicians “congestive bronchitis” -was set up. - -A very singular circumstance was noticed also as to the effects of -ozone on the different orders of animals. The above-mentioned effects, -and others which accompanied them, the description of which would be -out of place in these pages, were developed more freely in carnivorous -than in herbivorous animals. Rats, for example, were much more easily -influenced by ozone than rabbits were. - -The results of Dr. Richardson’s experiments prepare us to hear that -ozone-periods, though characterized by the absence of certain diseases, -bring with them their own forms of disease. Apoplexy, epilepsy, -and other similar diseases seem peculiarly associated with the -ozone-periods, insomuch that eighty per cent. of the deaths occurring -from them take place on days when ozone is present in the air in larger -quantities than usual. Catarrh, influenza, and affections of the -bronchial tubes, also affect the ozone-periods. - -We see, then, that we have much yet to learn respecting ozone before -we can pronounce definitively whether it is more to be welcomed or -dreaded. We must wait until the researches which are in progress have -been carried out to their conclusion, and perhaps even then further -modes of inquiry will have to be pursued before we can form a definite -opinion. - - - - -_DEW._ - - -There are few phenomena of common occurrence which have proved more -perplexing to philosophers than those which attend the deposition of -dew. Every one is familiar with these phenomena, and in very early -times observant men had noticed them; yet it is but quite recently -that the true theory of dew has been put forward and established. -This theory affords a striking evidence of the value of careful and -systematic observation applied even to the simplest phenomena of nature. - -It was observed, in very early times, that dew is only formed on -clear nights, when, therefore, the stars are shining. It was natural, -perhaps, though hardly philosophical, to conclude that dew is directly -shed down upon the earth from the stars; accordingly, we find the -reference of dew to stellar influences among the earliest theories -propounded in explanation of the phenomenon. - -A theory somewhat less fanciful, but still depending on supposed -stellar influences, was shortly put forward. It was observed that -dew is only formed when the atmosphere is at a low temperature; or, -more correctly, when the air is at a much lower temperature than has -prevailed during the daytime. Combining this peculiarity with the -former ancient philosophers reasoned in the following manner: Cold -generates dew, and dew appears only when the skies are clear—that is, -when the stars are shining; hence it follows that the stars generate -cold, and thus lead indirectly to the formation of dew. Hence arose -the singular theory, that as the sun pours down heat upon the earth, so -the stars (and also the moon and planets) pour down cold. - -Nothing is more common—we may note in passing—than this method of -philosophizing, especially in all that concerns weather-changes; and -perhaps it would be impossible to find a more signal instance of the -mistakes into which men are likely to fall when they adopt this false -method of reasoning; for, so far is it from being true that the stars -shed cold upon the earth, that the exact reverse is the case. It has -been established by astronomers and physicists that an important -portion of the earth’s heat-supply is derived from the stars. - -Following on these fanciful speculations came Aristotle’s theory -of dew—celebrated as one of the most remarkable instances of the -approximation which may sometimes be made to the truth by clever -reasoning on insufficient observations. For we must not fall into -the mistake of supposing, as many have done, that Aristotle framed -hypotheses without making observations; indeed, there has seldom lived -a philosopher who has made more observations than he did. His mistake -was that he extended his observations too widely, not making enough on -each subject. He imagined that, by a string of syllogisms, he could -make a few supply the place of many observations. - -Aristotle added two important facts to our knowledge respecting -dew—namely, first, that dew is only formed in serene weather; and -secondly, that it is not formed on the summits of mountains. Modern -observations show the more correct statement of the case to be that dew -is _seldom_ formed either in windy weather or on the tops of mountains. -Now, Aristotle reasoned in a subtle and able manner on these two -observations. He saw that dew must be the result of processes which -are interfered with when the air is agitated, and which do not extend -high above the earth’s surface; he conjectured, therefore, that dew is -simply caused by the discharge of vapour from the air. “Vapour is a -mixture,” he said, “of water and heat, and as long as water can get a -supply of heat, vapour rises. But vapour cannot rise high, or the heat -would get detached from it; and vapour cannot exist in windy weather, -but becomes dissipated. Hence, in high places, and in windy weather, -dew cannot be formed for want of vapour.” He derided the notion that -the stars and moon cause the precipitation of dew. “On the contrary, -the sun,” he said, “is the cause; since its heat raises the vapour, -from which the dew is formed when that heat is no longer present to -keep up the vapour.” - -Amidst much that is false, there is here a good deal that is sound. -The notion that heat is some substance which floats up the vapour, -and may become detached from it in high or windy places, is of course -incorrect. So also is the supposition that the dew is produced by -the _fall_ of condensed vapour as the heat passes away. Nor is it -correct to say that the absence of the sun causes the condensation of -vapour, since, as we shall presently see, the cold which causes the -deposition of dew results from more than the mere absence of the sun. -But, in pointing out that the discharge of vapour from the air, owing -to loss of heat, is the true cause of the deposition of dew, Aristotle -expressed an important truth. It was when he attempted to account for -the discharge that he failed. It will be observed, also, that his -explanation does not account for the observed fact that dew is only -formed in clear weather. - -Aristotle’s views did not find acceptance among the Greeks or Romans; -they preferred to look on the moon, stars, and planets as the agents -which cause the deposition of dew. “This notion,” says a modern author, -“was too beautiful for a Greek to give up, and the Romans could not do -better than follow the example of their masters.” - -In the middle ages, despite the credit attached to Aristotle’s name, -those who cultivated the physical sciences were unwilling to accept his -views; for the alchemists (who alone may be said to have been students -of nature) founded their hopes of success in the search for the -philosopher’s stone, the _elixir vitæ_, and the other objects of their -pursuit, on occult influences supposed to be exercised by the celestial -bodies. It was unlikely, therefore, that they would willingly reject -the ancient theory which ascribed dew to lunar and stellar radiations. - -But at length Baptista Porta adduced evidence which justified him in -denying positively that the moon or stars exercise any influence on the -formation of dew. He discovered that dew is sometimes deposited on the -inside of glass panes; and again, that a bell-glass placed over a plant -in cold weather is more copiously covered with dew within than without; -nay, he observed that even some opaque substances show dew on their -_under_ surface when none appears on the upper. Yet, singularly enough, -Baptista Porta rejected that part of Aristotle’s theory which was alone -correct. He thought his observations justified him in looking on dew -as condensed—not from vapour, as Aristotle thought—but from the air -itself. - -But now a new theory of dew began to be supported. We have seen that -not only the believers in stellar influence, but Aristotle also, looked -on dew as falling from above. Porta’s experiments were opposed to this -view. It seemed rather as if dew rose from the earth. Observation also -showed that the amount of dew obtained at different heights from the -ground diminishes with the height. Hence, the new theorists looked upon -dew as an exhalation from the ground and from plants—a fine steam, as -it were, rising upwards, and settling principally on the under surfaces -of objects. - -But this view, like the others, was destined to be overthrown. -Muschenbroek, when engaged in a series of observations intended to -establish the new view, made a discovery which has a very important -bearing on the theory of dew: he found that, instead of being deposited -with tolerable uniformity upon different substances,—as falling rain -is, for instance, and as the rising rain imagined by the new theorists -ought to be,—dew forms very much more freely on some substances than -on others. - -Here was a difficulty which long perplexed physicists. It appeared that -dew neither fell from the sky nor arose from the earth. The object -itself on which the dew was formed seemed to play an important part in -determining the amount of deposition. - -At length it was suggested that Aristotle’s long-neglected explanation -might, with a slight change, account for the observed phenomena. The -formation of dew was now looked upon as a discharge of vapour from the -air, this discharge not taking place necessarily upwards or downwards, -but always from the air next to the object. But it was easy to test -this view. It was understood that the coldness of the object, as -compared with the air, was a necessary element in the phenomenon. It -followed, that if a cold object is suddenly brought into warm air, -there ought to be a deposition of moisture upon the object. This was -found to be the case. Any one can readily repeat the experiment. If a -decanter of ice-cold water is brought into a warm room, in which the -air is not dry—a crowded room, for example—the deposition of moisture -is immediately detected by the clouding of the glass. But there is, in -fact, a much simpler experiment. When we breathe, the moisture in the -breath generally continues in the form of vapour. But if we breathe -upon a window-pane, the vapour is immediately condensed, because the -glass is considerably colder than the exhaled air. - -But although this is the correct view, and though physicists had made -a noteworthy advance in getting rid of erroneous notions, yet a theory -of dew still remained to be formed; for it was not yet shown how the -cold, which causes the deposition of dew, is itself occasioned. The -remarkable effects of a clear sky and serene weather in encouraging the -formation of dew, were also still unaccounted for. On the explanation -of these and similar points, the chief interest of the subject depends. -Science owes the elucidation of these difficulties to Dr. Wells, a -London physician, who studied the subject of dew in the commencement -of the present century. His observations were made in a garden three -miles from Blackfriars Bridge. - -Wells exposed little bundles of wool, weighing, when dry, ten grains -each, and determined by their increase in weight the amount of moisture -which had been deposited upon them. At first, he confined himself to -comparing the amount of moisture collected on different nights. He -found that although it was an invariable rule that cloudy nights were -unfavourable to the deposition of dew, yet that on some of the very -clearest and most serene nights, less dew was collected than on other -occasions. Hence it became evident that mere clearness was not the only -circumstance which favoured the deposition of dew. In making these -experiments, he was struck by results which appeared to be anomalous. -He soon found that these anomalies were caused by any obstructions -which hid the heavens from his wool-packs: such obstructions hindered -the deposition of dew. He tried a crucial experiment. Having placed -a board on four props, he laid a piece of wool _on_ the board, -and another _under_ it. During a clear night, he found that the -difference in the amount of dew deposited on the two pieces of wool -was remarkable: the upper one gained fourteen grains in weight, the -lower one gained only four grains. He made a little roof over one piece -of wool, with a sheet of pasteboard; and the increase of weight was -reduced to two grains, while a piece of wool outside the roof gained no -less than sixteen grains in weight. - -Leaving these singular results unexplained for a while, Dr. Wells -next proceeded to test the temperature near his wool-packs. He found -that where dew is most copiously produced, there the temperature is -lowest. Now, since it is quite clear that the deposition of dew was not -the cause of the increased cold—for the condensation of vapour is a -process _producing heat_—it became quite clear that the formation of -dew is dependent on and proportional to the loss of heat. - -And now Wells was approaching the solution of the problem he had set -himself; for it followed from his observations, that such obstructions -as the propped board and the pasteboard roof _kept in the heat_. It -followed also, from the observed effects of clear skies, that clouds -_keep in the heat_. Now, what sort of heat is that which is prevented -from escaping by the interference of screens, whether material or -vaporous? There are three processes by which heat is transmitted from -one body to another,—these are, conduction, convection, and radiation. -The first is the process by which objects in contact communicate -their heat to each other, or by which the heat in one part of a body -is gradually transmitted to another part. The second is the process -by which heat is carried from one place to another by the absolute -transmission of heated matter. The third is that process by which heat -is spread out in all directions, in the same manner as light. A little -consideration will show that the last process is that with which we -are alone concerned; and this important result flows from Dr. Wells’ -experiments, that _the rate of the deposition of dew depends on the -rate at which bodies part with their heat by radiation_. If the process -of radiation is checked, dew is less copiously deposited, and _vice -versâ_. - -When we consider the case of heat accompanied by light, we understand -readily enough that a screen may interfere with the emission of -radiant heat. We use a fire-screen, for instance, with the object of -producing just such an interference. But we are apt to forget that -what is true of luminous heat is true also of that heat which every -substance possesses. In fact, we do not meet with many instances in -which the effect of screens in preventing the loss of obscure heat is -very noteworthy. There are some, as the warmth of a green-house at -night, and so on; but they pass unnoticed, or are misunderstood. It -was in this way that the explanation of dew-phenomena had been so long -delayed. The very law on which it is founded had been _practically_ -applied, while its meaning had not been recognized. “I had often -in the pride of half-knowledge,” says Wells, “smiled at the means -frequently employed by gardeners to protect tender plants from cold, -as it appeared to me impossible that a thin mat, or any such flimsy -substance, could prevent them from attaining the temperature of the -atmosphere, by which alone I thought them liable to be injured. But -when I had seen that bodies on the surface of the earth become, during -a still and serene night, colder than the atmosphere, by radiating -their heat to the heavens, I perceived immediately a just reason for -the practice which I had before deemed useless.” - -And now all the facts which had before seemed obscure were accounted -for. It had been noticed that metallic plates were often dry when -grass or wood was copiously moistened. Now, we know that metals part -unwillingly with their heat by radiation, and therefore the temperature -of a metal plate exposed in the open air is considerably higher than -that of a neighbouring piece of wood. For a similar reason, dew is -more freely deposited on grass than on gravel. Glass, again, is a -good radiator, so that dew is freely deposited on glass objects,—a -circumstance which is very annoying to the telescopist. The remedy -employed is founded on Wells’ observations—a cylinder of tin or card, -called a dew-cap, is made to project beyond the glass, and thus to act -as a screen, and prevent radiation. - -We can now also interpret the effects of a clear sky. Clouds act the -part of screens, and check the emission of radiant heat from the earth. -This fact has been noticed before, but misinterpreted, by Gilbert White -of Selborne. “I have often observed,” he says, “that cold seems to -descend from above; for when a thermometer hangs abroad on a frosty -night, the intervention of a cloud shall immediately raise the mercury -ten degrees, and a clear sky shall again compel it to descend to its -former gauge.” Another singular mistake had been made with reference -to the power which clouds possess of checking the emission of radiant -heat. It had been observed that on moonlit nights the eyes are apt to -suffer in a peculiar way, which has occasionally brought on temporary -blindness. This had been ascribed to the moon’s influence, and the term -moon-blindness had therefore been given to the affection. In reality, -the moon has no more to do with this form of blindness than the stars -have to do with the formation of dew. The absence of clouds from the -air is the true cause of the mischief. There is no sufficient check -to the radiation of heat from the eyeballs, and the consequent chill -results in temporary loss of sight, and sometimes even in permanent -injury. - -Since clouds possess this important power, it is clear that while they -are present in the air there can never be a copious formation of dew, -which requires, as we have seen, a considerable fall in the temperature -of the air around the place of deposition. When the air is clear, -however, radiation proceeds rapidly, and therefore dew is freely formed. - -But it might seem that since objects in the upper regions of the air -part with their radiant heat more freely than objects on the ground, -the former should be more copiously moistened with dew than the latter. -That the fact is exactly the reverse is thus explained. The cold -which is produced by the radiation of heat from objects high in the -air is communicated to the surrounding air, which, growing heavier, -descends towards the ground, its place being supplied by warmer air. -Thus the object is prevented from reducing the air in its immediate -neighbourhood to so low a temperature as would be attained if this -process of circulation were checked. Hence, a concave vessel placed -below an object high in air, would serve to increase the deposition -of dew by preventing the transfer of the refrigerated air. We are not -aware that the experiment has ever been tried, but undoubtedly it would -have the effect we have described. An object on the ground grows cold -more rapidly, because the neighbouring air cannot descend after being -chilled, but continues in contact with the object; also cold air is -continually descending from the neighbourhood of objects higher in -air which are parting with their radiant heat, and the cold air thus -descending takes the place of warmer air, whose neighbourhood might -otherwise tend to check the loss of heat in objects on the ground. - -Here, also, we recognize the cause of the second peculiarity detected -by Aristotle—namely, that dew is only formed copiously in serene -weather. When there is wind, it is impossible that the refrigerated air -around an object which is parting with its radiant heat, can remain -long in contact with the object. Fresh air is continually supplying the -place of the refrigerated air, and thus the object is prevented from -growing so cold as it otherwise would. - -In conclusion, we should wish to point out the important preservative -influence exercised during the formation of dew. If the heat which is -radiated from the earth, or from objects upon it, during a clear night, -were not repaired in any way, the most serious injury would result to -vegetation. For instance, if the sun raised no vapour during the day, -so that when night came on the air was perfectly dry, and thus the -radiant heat passed away into celestial space without compensation, not -a single form of vegetation could retain its life during the bitter -cold which would result. But consider what happens. The sun’s heat, -which has been partly used up during the day in supplying the air -with aqueous vapour, is gradually given out as this vapour returns to -the form of water. Thus the process of refrigeration is effectually -checked, and vegetation is saved from destruction. There is something -very beautiful in this. During the day, the sun seems to pour forth his -heat with reckless profusion, yet all the while it is being silently -stored up; during the night, again, the earth seems to be radiating -her heat too rapidly into space, yet all the while a process is going -on by which the loss of heat is adequately compensated. Every particle -of dew which we brush from the blades of grass, as we take our morning -rambles, is an evidence of the preservative action of nature. - - - - -_THE LEVELLING POWER OF RAIN._ - - -It has been recognized, ever since geology has become truly a science, -that the two chief powers at work in remodelling the earth’s surface, -are fire and water. Of these powers one is in the main destructive, and -the other preservative. Were it not for the earth’s vulcanian energies, -there can be no question that this world would long since have been -rendered unfit for life,—at least of higher types than we recognize -among sea creatures. For at all times igneous causes are at work, -levelling the land, however slowly; and this not only by the action -of sea-waves at the border-line between land and water, but by the -action of rain and flood over inland regions. Measuring the destructive -action of water by what goes on in the lifetime of a man, or even -during many successive generations, we might consider its effects very -slight, even as on the other hand we might underrate the effects of the -earth’s internal fires, were we to limit our attention to the effects -of upheaval and of depression (not less preservative in the long run) -during a few hundreds or thousands of years. As Lyell has remarked in -his “Principles of Geology,” “our position as observers is essentially -unfavourable when we endeavour to estimate the nature and magnitude of -the changes now in progress. As dwellers on the land, we inhabit about -a fourth part of the surface; and that portion is almost exclusively -a theatre of decay, and not of reproduction. We know, indeed, that -new deposits are annually formed in seas and lakes, and that every -year some new igneous rocks are produced in the bowels of the earth, -but we cannot watch the progress of their formation; and as they are -only present to our minds by the aid of reflection, it requires an -effort both of the reason and the imagination to appreciate duly their -importance.” But that they are actually of extreme importance, that in -fact all the most characteristic features of our earth at present are -due to the steady action of these two causes, no geologist now doubts. - -I propose now to consider one form in which the earth’s aqueous -energies effect the disintegration and destruction of the land. The sea -destroys the land slowly but surely, by beating upon its shores and by -washing away the fragments shaken down from cliffs and rocks, or the -more finely divided matter abstracted from softer strata. In this work -the sea is sometimes assisted by the other form of aqueous energy—the -action of rain. But in the main, the sea is the destructive agent by -which shore-lines are changed. The other way in which water works the -destruction of the land affects the interior of land regions, or only -affects the shore-line by removing earthy matter from the interior of -continents to the mouths of great rivers, whence perhaps the action of -the sea may carry it away to form shoals and sandbanks. I refer to the -direct and indirect effects of the downfall of rain. All these effects, -without a single exception, tend to level the surface of the earth. The -mountain torrent whose colour betrays the admixture of earthy fragments -is carrying those fragments from a higher to a lower level. The river -owes its colour in like manner to earth which it is carrying down to -the sea level. The flood deposits in valleys matter which has been -withdrawn from hill slopes. Rainfall, acts, however, in other ways, and -sometimes still more effectively. The soaked slopes of great hills give -way, and great landslips occur. In winter the water which has drenched -the land freezes, in freezing expands, and then the earth crumbles and -is ready to be carried away by fresh rains; or when dry, by the action -even of the wind alone. Landslips, too, are brought about frequently in -the way, which are even more remarkable than those which are caused by -the unaided action of heavy rainfalls. - -The most energetic action of aqueous destructive forces is seen when -water which has accumulated in the higher regions of some mountain -district breaks its way through barriers which have long restrained it, -and rushes through such channels as it can find or make for itself into -valleys and plains at lower levels. Such catastrophes are fortunately -not often witnessed in this country, nor when seen do they attain the -same magnitude as in more mountainous countries. It would seem, indeed, -as though they could attain very great proportions only in regions -where a large extent of mountain surface lies above the snow-line. -The reason why in such regions floods are much more destructive than -elsewhere will readily be perceived if we consider the phenomena of one -of these terrible catastrophes. - -Take, for instance, the floods which inundated the plains of Martigny -in 1818. Early in that year it was found that the entire valley of the -Bagnes, one of the largest side-valleys of the great valley of the -Rhône, above Geneva, had been converted into a lake through the damming -up of a narrow outlet by avalanches of snow and ice from a loftier -glacier overhanging the bed of the river Dranse. The temporary lake -thus formed was no less than half a league in length, and more than -200 yards wide, its greatest depth exceeding 200 feet. The inhabitants -perceived the terrible effects which must follow when the barrier -burst, which it could not fail to do in the spring. They, therefore, -cut a gallery 700 feet long through the ice, while as yet the water -was at a moderate height. When the waters began to flow through this -channel, their action widened and deepened it considerably. At length -nearly half the contents of the lake were poured off. Unfortunately, -as the heat of the weather increased, the middle of the barrier slowly -melted away, until it became too weak to withstand the pressure of -the vast mass of water. Suddenly it gave way; and so completely that -all the water in the lake rushed out in half an hour. The effects of -this tremendous outrush of the imprisoned water were fearful. “In -the course of their descent,” says one account of the catastrophe, -“the waters encountered several narrow gorges, and at each of these -they rose to a great height, and then burst with new violence into the -next basin, sweeping along forests, houses, bridges, and cultivated -land.” It is said by those who witnessed the passage of the flood at -various parts of its course, that it resembled rather a moving mass -of rock and mud than a stream of water. “Enormous masses of granite -were torn out of the sides of the valleys, and whirled for hundreds -of yards along the course of the flood.” M. Escher the engineer tells -us that a fragment thus whirled along was afterwards found to have a -circumference of no less than sixty yards. “At first the water rushed -on at a rate of more than a mile in three minutes, and the whole -distance (forty-five miles) which separates the Valley of Bagnes from -the Lake of Geneva was traversed in little more than six hours. The -bodies of persons who had been drowned in Martigny were found floating -on the further side of the Lake of Geneva, near Vevey. Thousands of -trees were torn up by the roots, and the ruins of buildings which had -been overthrown by the flood were carried down beyond Martigny. In -fact, the flood at this point was so high, that some of the houses in -Martigny were filled with mud up to the second story.” - -It is to be noted respecting this remarkable flood, that its effects -were greatly reduced in consequence of the efforts made by the -inhabitants of the lower valleys to make an outlet for the imprisoned -waters. It was calculated by M. Escher that the flood carried down -300,000 cubic feet of water every second, an outflow five times as -great as that of the Rhine below Basle. But for the drawing off of the -temporary lake, the flood, as Lyell remarks, would have approached in -volume some of the largest rivers in Europe. “For several months after -the _débâcle_ of 1818,” says Lyell, “the Dranse, having no settled -channel, shifted its position continually from one side to the other of -the valley, carrying away newly erected bridges, undermining houses, -and continuing to be charged with as large a quantity of earthy -matter as the fluid could hold in suspension. I visited this valley -four months after the flood, and was witness to the sweeping away of -a bridge and the undermining of part of a house. The greater part of -the ice-barrier was then standing, presenting vertical cliffs 150 feet -high, like ravines in the lava-currents of Etna, or Auvergne, where -they are intersected by rivers.” It is worthy of special notice that -inundations of similar or even greater destructiveness have occurred in -the same region at former periods. - -It is not, however, necessary for the destructive action of floods -in mountain districts that ice and snow should assist, as in the -Martigny flood. In October, 1868, the cantons of Tessin, Grisons, Uri, -Valois, and St. Gall, suffered terribly from the direct effects of -heavy rainfall. The St. Gothard, Splugen, and St. Bernhardin routes -were rendered impassable. In the former pass twenty-seven lives were -lost, besides many horses and waggons of merchandise. On the three -routes more than eighty persons in all perished. In the small village -of Loderio alone, no less than fifty deaths occurred. The damage in -Tessin was estimated at £40,000. In Uri and Valois large bridges were -destroyed and carried away. Everything attested the levelling power -of rain; a power which, when the rain is falling steadily on regions -whence it as steadily flows away, we are apt to overlook. - -It is not, however, necessary to go beyond our own country for -evidence of the destructive action of water. We have had during the -past few years very striking evidence in this respect, which need -scarcely be referred to more particularly here, because it will be -in the recollection of all our readers. Looking over the annals of -the last half-century only, we find several cases in which the power -of running water in carrying away heavy masses of matter has been -strikingly shown. Consider, for instance, the effects of the flood in -Aberdeenshire and the neighbouring counties, early in August, 1829. In -the course of two days a great flood extended itself over “that part of -the north-east of Scotland which would be cut off by two lines drawn -from the head of Loch Rannoch, one towards Inverness and the other to -Stonehaven.” The total length of various rivers in this region which -were flooded amounted to between 500 and 600 miles. Their courses were -marked everywhere by destroyed bridges, roads, buildings, and crops. -Sir T. D. Lauder records “the destruction of thirty-eight bridges, and -the entire obliteration of a great number of farms and hamlets. On the -Nairn, a fragment of sandstone fourteen feet long by three feet wide -and one foot thick, was carried about 200 yards down the river. Some -new ravines were formed on the sides of mountains where no streams had -previously flowed, and ancient river channels, which had never been -filled from time immemorial, gave passage to a copious flood.” But -perhaps the most remarkable effect of these inundations was the entire -destruction of the bridge over the Dee at Ballater. It consisted of -five arches, spanning a waterway of 260 feet. The bridge was built of -granite, the pier, resting on rolled pieces of granite and gneiss. -We read that the different parts of this bridge were swept away in -succession by the flood, the whole mass of masonry disappearing in the -bed of the river. Mr. Farquharson states that on his own premises the -river Don forced a mass of 400 or 500 tons of stones, many of them of -200 or 300 pounds’ weight, up an inclined plane, rising six feet in -eight or ten yards, and left them in a rectangular heap about three -feet deep on a flat ground, the heap ending abruptly at its lower -extremity.” At first sight this looks like an action the reverse of -that levelling action which we have here attributed to water. But in -reality it indicates the intense energy of this action; which drawing -heavy masses down along with swiftly flowing water, communicates to -them so great a momentum, that on encountering in their course a rising -slope, they are carried up its face and there left by the retreating -flood. The rising of these masses no more indicates an inherent -uplifting power in running water, than the ascent of a gently rising -slope by a mass which has rolled headlong down the steep side of a -hill indicates an upward action exerted by the force of gravity. - -Even small rivers, when greatly swollen by rain, exhibit great energy -in removing heavy masses. Thus Lyell mentions that in August, 1827, the -College, a small river which flows down a slight declivity from the -eastern watershed of the Cheviot Hills, carried down several thousand -tons’ weight of gravel and sand to the plain of the Till. This little -river also carried away a bridge then in process of building, “some of -the arch stones of which, weighing from half to three-quarters of a ton -each, were propelled two miles down the rivulet.” “On the same occasion -the current tore away from the abutment of a mill-dam a large block -of greenstone porphyry, weighing nearly two tons, and transported it -to a distance of nearly a quarter of a mile. Instances are related as -occurring repeatedly, in which from 1000 to 3000 tons of gravel are in -like manner removed by this streamlet to still greater distances in one -day.” - -It may appear, however, to the reader that we have in such instances -as these the illustration of destructive agencies which are of their -very nature limited within very narrow areas. The torrent, or even -the river, may wear out its bed or widen it, but nevertheless can -hardly be regarded as modifying the aspect of the region through which -it flows. Even in this respect, however, the destructive action of -water is not nearly so limited as it might appear to be. Taking a few -centuries or a few thousand years, no doubt, we can attribute to the -action of rivers, whether in ordinary flow or in flood, little power -of modifying the region which they drain. But taking that wider survey -(in time) of fluviatile work which modern science requires, dealing -with this form of aqueous energy as we deal with the earth’s vulcanian -energies, we perceive that the effects of river action in the course of -long periods of time are not limited to the course which at any given -time a river may pursue. In carrying down material along its course -to the sea, a river is not merely wearing down its own bed, but is so -changing it that in the course of time it will become unfit to drain -the region through which it flows. Its bottom must of necessity become -less inclined. Now although it will then be lower than at present, -and therefore be then even more than now the place to which the water -falling upon the region traversed by the river will naturally tend, -it will no longer carry off that water with sufficient velocity. -Three consequences will follow from this state of things. In the -first place there will be great destruction in the surrounding region -through floods because of inadequate outflow; in the second place, the -overflowing waters will in the course of time find new channels, or in -other words new rivers will be formed in this region; thirdly, owing to -the constant presence of large quantities of water in the depressed bed -of the old river, the banks on either side will suffer, great landslips -occurring and choking up its now useless channel. Several rivers are -undergoing these changes at the present time, and others, which are -manifestly unfit for the work of draining the region through which they -flow (a circumstance attested by the occurrence of floods in every wet -season), must before long be modified in a similar way. - -We are thus led to the consideration of the second form in which -the destructive action of inland waters, or we may truly say, the -destructive action of _rain_, is manifested,—viz., in landslips. -These, of course, are also caused not unfrequently by vulcanian action, -but equally of course landslips so caused do not belong to our present -subject. Landslips caused directly or indirectly by rain, are often -quite as extensive as those occasioned by vulcanian energy, and they -are a great deal more common. We may cite as a remarkable instance -a landslip of nearly half a mile in breadth, now in progress, in a -district of the city of Bath called Hedgmead, which forms a portion -of the slope of Beacon Hill. It is attributed to the action of a -subterranean stream on a bed of gravel, the continued washing away of -which causes the shifting; but the heavy rains of 1876–77 caused the -landslip to become much more marked. - -Besides slow landslips, however, rain not unfrequently causes great -masses of earth to be precipitated suddenly, and where such masses fall -into the bed of a river, local deluges of great extent and of the most -destructive character often follow. The following instances, cited in -an abridged form from the pages of Lyell’s “Principles of Geology,” -attest the terrible nature of catastrophes such as these. - -Two dry seasons in the White Mountains of New Hampshire were followed -by heavy rains on August 28, 1826. From the steep and lofty slopes -of the River Saco great masses of rock and stone were detached, and -descending carried along with them “in one promiscuous and frightful -ruin, forests, shrubs, and the earth which sustained them.” “Although -there are numerous indications on the steep sides of these hills of -former slides of the same kind, yet no tradition had been handed down -of any similar catastrophe within the memory of man, and the growth of -the forest on the very spots now devastated clearly showed that for a -long interval nothing similar had occurred. One of these moving masses -was afterwards found to have slid three miles, with an average breadth -of a quarter of a mile.” At the base of the vast chasms formed by these -natural excavations, a confused mass of ruins was seen, consisting of -transported earth, gravel, rocks, and trees. Forests were prostrated -with as much ease as if they had been mere fields of grain; if they -resisted for a while, “the torrent of mud and rock accumulated behind -till it gathered sufficient force to burst the temporary barrier.” -“The valleys of the Amonoosuck and Saco presented, for many miles, an -uninterrupted scene of desolation, all the bridges being carried away, -as well as those over the tributary streams. In some places the road -was excavated to the depth of from fifteen to twenty feet; in others -it was covered with earth, rocks, and trees to as great a height. -The water flowed for many weeks after the flood, as densely charged -with earth as it could be without being changed into mud, and marks -were seen in various localities of its having risen on either side of -the valley to more than twenty-five feet above the ordinary level.” -But perhaps the most remarkable evidence of the tremendous nature -of this cataclysm is to be found in Lyell’s statements respecting -the condition of the region nineteen years later. “I found the signs -of devastation still very striking,” he says; “I also particularly -remarked that the surface of the bare granite rocks had been smoothed -by the passage over them of so much mud and stone.” Professor Hubbard -mentions in _Silliman’s Journal_ that “in 1838 the deep channels worn -by the avalanches of mud and stone, and the immense heaps of boulders -and blocks of granite in the river channel, still formed a picturesque -feature in the scenery.” - -It will readily be understood that when destruction such as this -follows from landslips along the borders of insignificant rivers, -those occurring on the banks of the mighty rivers which drain whole -continents are still more terrible. The following account from the pen -of Mr. Bates the naturalist, indicates the nature of the landslips -which occur on the banks of the Amazon. “I was awoke before sunrise, -one morning,” he says, “by an unusual sound resembling the roar of -artillery; the noise came from a considerable distance, one crash -succeeding another. I supposed it to be an earthquake, for, although -the night was breathlessly calm, the broad river was much agitated, -and the vessel rolled heavily. Soon afterwards another loud explosion -took place, followed by others which lasted for an hour till the day -dawned, and we then saw the work of destruction going forward on the -other side of the river, about three miles off. Large masses of forest, -including trees of colossal size, probably 200 feet in height, were -rocking to and fro, and falling headlong one after another into the -water. After each avalanche the wave which it caused returned on the -crumbly bank with tremendous force, and caused the fall of other masses -by undermining. The line of coast over which the landslip extended was -a mile or two in length; the end of it, however, was hid from our view -by an intervening island. It was a grand sight; each downfall created -a cloud of spray; the concussion in one place causing other masses -to give way a long distance from it, and thus the crashes continued, -swaying to and fro, with little prospect of termination. When we glided -out of sight two hours after sunrise the destruction was still going -on.” - -We might consider here the action of glaciers in gradually grinding -down the mountain slopes, the destructive action of avalanches, and a -number of other forms in which snow and ice break down by slow degrees -the upraised portions of the earth. For in reality all these forms of -destructive action take their origin in the same process whence running -waters and heavy rainfalls derive their power. All these destructive -agencies are derived from the vapour of water in the air. But it seems -better to limit the reader’s attention in this place to the action of -water in the liquid form; and therefore we proceed to consider the -other ways in which rain wears down the land. - -Hitherto we have considered effects which are produced chiefly along -the courses of rivers, or in their neighbourhood. But heavy rainfall -acts, and perhaps in the long run as effectively (when we remember the -far wider region affected) over wide tracts of nearly level ground, as -along the banks of torrents and rivers. - -The rain which falls on plains or gently undulating surfaces, although -after a while it dries up, yet to some degree aids in levelling the -land, partly by washing down particles of earth, however slowly, to -lower levels, partly by soaking the earth and preparing a thin stratum -of its upper surface to be converted into dust, and blown away by the -wind. But it is when very heavy storms occur that the levelling action -of rain over widely extending regions can be most readily recognized. -Of this fact observant travellers cannot fail to have had occasional -evidence. Sir Charles Lyell mentions one instance observed by him, -which is specially interesting. “During a tour in Spain,” he says, -“I was surprised to see a district of gently undulating ground in -Catalonia, consisting of red and grey sandstone, and in some parts -of red marl, almost entirely denuded of herbage, while the roots of -the pines, holm oaks, and some other trees, were half exposed, as if -the soil had been washed away by a flood. Such is the state of the -forests, for example, between Oristo and Vich, and near San Lorenzo. -But being overtaken by a violent thunderstorm, in the month of August, -I saw the whole surface, even the highest levels of some flat-topped -hills, streaming with mud, while on every declivity the devastation -of torrents was terrific. The peculiarities in the physiognomy of the -district were at once explained, and I was taught that, in speculating -on the greater effects which the direct action of rain may once have -produced on the surface of certain parts of England, we need not revert -to periods when the heat of the climate was tropical.” He might have -cited instances of such storms occurring in England. For example, -White, in his delightful “Natural History of Selborne,” describes -thus the effects of a storm which occurred on June 5, 1784: “At about -a quarter after two the storm began in the parish of Harpley, moving -slowly from north to south, and from thence it came over Norton Farm -and so to Grange Farm, both in this parish. Had it been as extensive -as it was violent (for it was very short) it must have ravaged all the -neighbourhood. The extent of the storm was about two miles in length -and one in breadth. There fell prodigious torrents of rain on the farms -above mentioned, which occasioned a flood as violent as it was sudden, -doing great damage to the meadows and fallows by deluging the one and -washing away the soil of the other. The hollow lane towards Alton was -so torn and disordered as not to be passable till mended, rocks being -removed which weighed two hundredweight.” - -We have mentioned the formation of dust, and the action of wind upon -it, as a cause tending to level the surface of the land. It may appear -to many that this cause is too insignificant to be noticed among those -which modify the earth’s surface. In reality, however, owing to its -continuous action, and to its always acting (in the main) in one -direction, this cause is much more important than might be supposed. -We overlook its action as actually going on around us, because in a -few years, or in a few generations, it produces no change that can be -readily noticed. But in long periods of time it changes very markedly -the level of lower lands, and that too even in cities, where means -exist for removing the accumulations of dust which are continually -collecting on the surface of the earth. We know that the remains of -old Roman roads, walls, houses, and so forth, in this country, are -found, not at the present level of the surface, but several feet—in -some cases many yards—below this level. The same holds elsewhere, -under the same conditions—that is, where we know quite certainly -that the substances thus found underground were originally on the -surface, and that there has been neither any disturbance causing them -to be engulfed, nor any deposition of scoriæ, volcanic dust, or other -products of subterranean disturbance. We cannot hesitate to regard this -burying of old buildings as due to the continual deposition of dust, -which eventually becomes compacted into solid earth. We know, moreover, -that the formation of dust is in the main due to rain converting the -surface layers of the earth into mud, which on drying requires but the -frictional action of heavy winds to rise in clouds of dust. In some -soils this process goes on more rapidly than in others, as every one -who has travelled much afoot is aware. There are parts of England, for -instance, where, even in the driest summer, the daily deposition of -dust on dry and breezy days is but slight, others where in such weather -a dust layer at least a quarter of an inch in thickness is deposited -in the course of a day. If we assumed, which would scarcely seem an -exaggerated estimate, that in the course of a single year a layer of -dust averaging an inch in thickness is deposited over the lower levels -of the surface of the land, we should find that the average depth of -the layer formed in the last thousand years would amount to no less -than eighty-three feet. Of course in inhabited places the deposition -of dust is checked, though not so much as most persons imagine. There -is not probably in this country a single building five hundred years -old, originally built at a moderately low level, the position of whose -foundation does not attest the constant gathering of matter upon the -surface. The actual amount by which the lower levels are raised and -the higher levels diminished in the course of a thousand years may be -very much less, but that it must amount to many feet can scarcely be -questioned. - -And as in considering the action of rain falling over a wide range of -country, we have to distinguish between the slow but steady action -of ordinary rains and the occasional violent action of great storms -of rain, so in considering the effects of drought following after -rain which has well saturated the land we have to distinguish between -ordinarily dusty times and occasions when in a very short time, owing -to the intensity of the heat and the violence of the wind large -quantities of dust are spread over a wide area. Darwin thus describes -the effect of such exceptional drought, as experienced in the years -1827–1832 in Buenos Ayres:—“So little rain fell that the vegetation, -even to the thistles, failed; the brooks were dried up, and the -whole country assumed the appearance of a dusty high road. This was -especially the case in the northern part of the province of Buenos -Ayres, and the southern part of Santa Fé.” He describes the loss of -life caused by the want of water, and many remarkable circumstances of -the drought which do not here specially concern us. He then goes on to -speak of the dust which gathered over the open country. “Sir Woodbine -Parish,” he says, “informed me of a very curious source of dispute. -The ground being so long dry, such quantities of dust were blown about -that in this open country the landmarks became obliterated, and people -could not tell the limits of their estates.” The dust thus scattered -over the land, whether left or removed, necessarily formed part of the -solid material brought from higher to lower levels, indirectly (in -this case) through the action of rain; for a drought can only convert -into friable matter earth which has before been thoroughly soaked. But -the action of rain, which had originally led to the formation of these -enormous masses of dust, presently took part in carrying the dust in -the form of mud to yet lower levels. “Subsequently to the drought of -1827 to 1832,” proceeds Darwin, “a very rainy season followed, which -caused great floods. Hence it is almost certain that some thousands -of the skeletons” (of creatures whose deaths he had described before) -“were buried by the deposits of the very next year. What could be the -opinion of a geologist, viewing such an enormous collection of bones, -of all kinds of animals and of all ages, thus embedded in one thick -earthy mass? Would he not attribute it to a flood having swept over the -surface of the land, rather than to the common order of things?” In -fact, a single great drought, followed by a very rainy season, must in -this instance, which was however altogether exceptional, have produced -a layer or stratum such as geologists would ordinarily regard as the -work of a much longer time and much more potent disturbing causes. - -It may be well to consider in this place the question whether in -reality the quantity of rain which falls now during our winter months -does not greatly exceed that which formerly fell in that part of -the year. The idea is very prevalent that our winters have changed -entirely in character in recent times, and the fear (or the hope?) is -entertained that the change may continue in the same direction until -wet and mild winters replace altogether the cold which prevailed in -former years. There is no sufficient reason, however, for supposing -that any such change is taking place. It is, indeed, not difficult to -find in the meteorological annals of the first half of the present -century, instances of the occurrence of several successive winters very -unlike the greater number of those which we have experienced during -the last ten or twelve years. But if we take any considerable series -of years in the last century we find the alternations of the weather -very similar to those we at present recognize. Consider, for instance, -Gilbert White’s brief summary of the weather from 1768 onwards:— - -For the winter of 1768–69 we have October and the first part of -November rainy; thence to the end of 1768 alternate rains and frosts; -January and February frosty and rainy, with gleams of fine weather; to -the middle of March, wind and rain. - -For the winter of 1769–70 we have October frosty, the next fortnight -rainy, the next dry and frosty. December windy, with rain and intervals -of frost (the first fortnight very foggy); the first half of January -frosty, thence to the end of February mild hazy weather. March frosty -and brighter. - -For 1770–71, from the middle of October to the end of the year, almost -incessant rains; January severe frosts till the last week, the next -fortnight rain and snow, and spring weather to the end of February. -March frosty. - -For 1771–72, October rainy, November frost with intervals of fog and -rain, December bright mild weather with hoar frosts; then six weeks of -frost and snow, followed by six of frost, sleet, hail, and snow. - -For 1772–73, October, November, and to December 22, rain, with mild -weather; to the end of 1772, cold foggy weather; then a week of frost, -followed by three of dark rainy weather. First fortnight of February -frost; thence to the end of March misty showery weather. - -Passing over the winter of 1773–74, which was half rainy, half frosty, -what could more closely resemble the winter weather we have had so much -of during the last few years, than that experienced in the winter of -1774–75? From August 24 to the third week of November, there was rain, -with frequent intervals of sunny weather; to the end of December, dark -dripping fogs; to the end of the first fortnight in March, rain almost -every day. - -And so on, with no remarkable changes, until the year 1792, the last of -Gilbert White’s records. - -If we limit our attention to any given month of winter, we find the -same mixture of cold and dry with wet and open weather as we are -familiar with at present. Take, for instance, the month usually the -most wintry of all, viz., January. Passing over the years already -considered, we have January, 1776, dark and frosty with much snow -till the 26th (at this time the Thames was frozen over), then foggy -with hoar frost; January, 1777, frosty till the 10th, then foggy and -showery; 1778, frosty till the 13th, then rainy to the 24th, then -hard frost; 1779, frost and showers throughout January; 1780, frost -throughout; 1781, frost and snow to the 25th, then rain and snow; -1782, open and mild; 1783, rainy with heavy winds; 1784, hard frost; -1785, a thaw on the 2nd, then rainy weather to the 28th, the rest of -the month frosty; 1786, frost and snow till January 7, then a week -mild with much rain, the next week heavy snow, and the rest mild with -frequent rain; 1787, first twenty-four days dark moist mild weather, -then four days frost, the rest mild and showery; 1788, thirteen days -mild and wet, five days of frost, and from January 18 to the end of the -month dry windy weather; 1789, thirteen days hard frost, the rest of -the month mild with showers; 1790, sixteen days of mild foggy weather -with occasional rain, to the 21st frost, to the 28th dark with driving -rains, and the rest mild dry weather; 1791, the whole of January mild -with heavy rains; and lastly 1792, “some hard frost in January, but -mostly wet and mild.” - -There is nothing certainly in this record to suggest that any material -change has taken place in our January weather during the last eight -years. And if we had given the record of the entire winter for each of -the years above dealt with the result would have been the same. - -We have, in fact, very striking evidence in Gilbert White’s account -of the cold weather of December, 1784, which he specially describes -as “very extraordinary,” to show that neither our severe nor our -average winter weather can differ materially from that which people -experienced in the eighteenth century. “In the evening of December 9,” -he says, “the air began to be so very sharp that we thought it would be -curious to attend to the motions of a thermometer; we therefore hung -out two, one made by Martin and one by Dolland” (_sic_, presumably -Dollond), “which soon began to show us what we were to expect; for by -ten o’clock they fell to twenty-one, and at eleven to four, when we -went to bed. On the 10th, in the morning the quicksilver in Dolland’s -glass was down to half a degree below zero, and that of Martin’s, which -was absurdly graduated only to four degrees above zero, sank quite -into the brass guard of the ball, so that when the weather became most -interesting this was useless. On the 10th, at eleven at night, though -the air was perfectly still, Dolland’s glass went down to one degree -below zero!” The note of exclamation is White’s. He goes on to speak -of “this strange severity of the weather,” which was not exceeded -that winter, or at any time during the twenty-four years of White’s -observations. Within the last quarter of a century, the thermometer, -on more than one occasion, has shown two or three degrees below zero. -Certainly the winters cannot be supposed to have been ordinarily -severer than ours in the latter half of the last century, when we find -that thermometers, by well-known instrument makers, were so constructed -as to indicate no lower temperature than four degrees above zero. - -Let us return, after this somewhat long digression, to the levelling -action of rain and rivers. - -If we consider this action alone, we cannot but recognize in it a cause -sufficient to effect the removal of all the higher parts of the land -to low levels, and eventually of all the low-lying land to the sea, in -the course of such periods as geology makes us acquainted with. The -mud-banks at the mouths of rivers show only a part of what rain and -river action is doing, yet consider how enormous is the mass which is -thus carried into the sea. It has been calculated that in a single week -the Ganges alone carries away from the soil of India and delivers -into the sea twice as much solid substance as is contained in the -great pyramid of Egypt. “The Irrawaddy,” says Sir J. Herschel, “sweeps -off from Burmah 62 cubit feet of earth in every second of time on an -average, and there are 86,400 seconds in every day, and 365 days in -every year; and so on for other rivers. Nor is there any reason to fear -or hope that the rains will cease, and this destructive process come to -an end. For though the quantity of water on the surface of the earth -is probably undergoing a slow process of diminution, small portions of -it year by year taking their place as waters under the earth,[44] yet -these processes are far too slow to appreciably affect the supply of -water till a far longer period has elapsed than that during which (in -all probability) life can continue upon the earth. - -When we consider the force really represented by the downfall of rain, -we need not greatly wonder that the levelling power of rain is so -effective. The sun’s heat is the true agent in thus levelling the -earth, and if we regard, as we justly may, the action of water, whether -in the form of rain or river, or of sea-wave raised by wind or tide, as -the chief levelling and therefore destructive force at work upon the -earth, and the action of the earth’s vulcanian energies as the chief -restorative agent, then we may fairly consider the contest as lying -between the sun’s heat and the earth’s internal heat. There can be -little question as to what would be the ultimate issue of the contest -if land and sea and air all endured or were only so far modified as -they were affected by these causes. Sun-heat would inevitably prevail -in the long run over earth-heat. But we see from the condition of -our moon how the withdrawal of water and air from the scene must -diminish the sun’s power of levelling the irregularities of the earth’s -surface. We say advisedly _diminish_, not _destroy_; for there can be -no question that the solar heat alternating with the cold of the long -lunar night is still at work levelling, however slowly, the moon’s -surface; and the same will be the case with our earth when her oceans -and atmosphere have disappeared by slow processes of absorption. - -The power actually at work at present in producing rain, and so, -indirectly, in levelling the earth’s surface, is enormous. I have shown -that the amount of heat required to evaporate a quantity of water which -would cover an area of 100 square miles to a depth of one inch would -be equal to the heat which would be produced by the combustion of half -a million tons of coals, and that the amount of force of which this -consumption of heat would be the equivalent corresponds to that which -would be required to raise a weight of upwards of one thousand millions -of tons to a height of one mile.[45] When we remember that the land -surface of the earth amounts to about fifty millions of square miles, -we perceive how enormous must be the force-equivalent of the annual -rainfall of our earth. We are apt to overlook when contemplating the -silent and seemingly quiet processes of nature—such as the formation -of the rain-cloud or the precipitation of rain—the tremendous energy -of the forces really causing these processes. “I have seen,” says -Professor Tyndall, “the wild stone-avalanches of the Alps, which smoke -and thunder down the declivities with a vehemence almost sufficient to -stun the observer. I have also seen snow-flakes descending so softly -as not to hurt the fragile spangles of which they were composed; yet -to produce from aqueous vapour a quantity which a child could carry of -that tender material demands an exertion of energy competent to gather -up the shattered blocks of the largest stone-avalanche I have ever -seen, and pitch them to twice the height from which they fell.” - - - - -_ANCIENT BABYLONIAN ASTROGONY._ - - -It is singular to consider how short a time elapsed, after writings -in the arrow-headed or cuneiform letters (the Keilschriften of the -Germans) were discovered, before, first, the power of interpreting them -was obtained, and, secondly, the range of the cuneiform literature -(so to speak) was recognized. Not more than ninety years have passed -since the first specimens of arrow-headed inscriptions reached Europe. -They had been known for a considerable time before this. Indeed, it -has been supposed that the Assyrian letters referred to by Herodotus, -Thucydides, and Pliny, were in this character. Della Valle and -Figueroa, early in the seventeenth century, described inscriptions in -arrow-headed letters, and hazarded the idea that they are to be read -from left to right. But no very satisfactory evidence was advanced to -show whether the inscriptions were to be so read, or from right to -left, or, as Chardin suggested, in vertical lines. The celebrated Olaus -Gerhard Tychsen, of Rostock, and other German philologists, endeavoured -to decipher the specimens which reached Europe towards the end of the -last century; but their efforts, though ingenious and zealous, were not -rewarded with success. In 1801 Dr. Hager advanced the suggestion that -the combinations formed by the arrow-heads did not represent letters -but words, if not entire sentences. Lichtenstein, on the other hand, -maintained that the letters belonged to an old form of the Arabic -or Coptic character; and he succeeded to his own satisfaction in -finding various passages from the Koran in the cuneiform inscriptions. -Dr. Grotefend was the first to achieve any real success in this line -of research. It is said that he was led to take up the subject by a -slight dispute with one of his friends, which led to a wager that he -would decipher one of the cuneiform inscriptions. The results of his -investigations were that cuneiform inscriptions are alphabetical, not -hieroglyphical; that the language employed is the basis of most of the -Eastern languages; and that it is written from right to left. Since -his time, through the labours of Rich, Botta, Rawlinson, Hincks, De -Saulcy, Layard, Sayce, George Smith, and others, the collection and -interpretation of the arrow-headed inscriptions have been carried -out with great success. We find reason to believe that, though the -original literature of Babylon was lost, the tablet libraries of -Assyria contained copies of most of the writings of the more ancient -nation. Amongst these have been found the now celebrated descriptions -of the Creation, the Fall of Man, the Deluge, the Tower of Babel, and -other matters found in an abridged and expurgated form in the book of -Genesis. It is to that portion of the Babylonian account which relates -to the creation of the sun and moon and stars that I wish here to call -attention. It is not only curious in itself, but throws light, in my -opinion, on questions of considerable interest connected with the views -of ancient Eastern nations respecting the heavenly bodies. - -It may be well, before considering the passage in question, to consider -briefly—though we may not be able definitely to determine—the real -antiquity of the Babylonian account. - -In Smith’s interesting work on the Chaldæan account of Genesis, the -question whether the Babylonian account preceded the writing of the -book of Genesis, or _vice versâ_, is not definitely dealt with. -Probably this part of his subject was included among the “important -comparisons and conclusions with respect to Genesis” which he preferred -to avoid, as his “desire was first to obtain the recognition of the -evidence without prejudice.” It might certainly have interfered to -some degree with the unprejudiced recognition of the evidence of the -tablets if it had been maintained by him, and still more if he had -demonstrated, that the Babylonian is the earlier version. For the -account in the book of Genesis, coming thus to be regarded as merely an -expurgated version of a narrative originally containing much fabulous -matter, and not a little that is monstrous and preposterous, would -certainly not have been presented to us in quite that aspect in which -it had long been regarded by theologians. - -But although Mr. Smith states that he placed the various dates as low -as he fairly could, considering the evidence,—nay, that he “aimed to -do this rather than to establish any system of chronology,”—there can -be no mistake about the relative antiquity which he in reality assigns -to the Babylonian inscriptions. He states, indeed, that every copy of -the Genesis legends belongs to the reign of Assurbanipal, who reigned -over Assyria B.C. 670. But it is “acknowledged on all hands that the -tablets are not the originals, but are only copies from earlier texts.” -The Assyrians acknowledge themselves that this literature was borrowed -from Babylonian sources, and of course it is to Babylonia we have to -look to ascertain the approximate dates of the original documents. -“The difficulty,” he proceeds, “is increased by the following -considerations: it appears that at an early period in Babylonian -history a great literary development took place, and numerous works -were produced which embodied the prevailing myths, religion, and -science of that day. Written, many of them, in a noble style of poetry -on one side, or registering the highest efforts of their science on -the other, these texts became the standards for Babylonian literature, -and later generations were content to copy these writings instead of -making new works for themselves. Clay, the material on which they were -written, was everywhere abundant, copies were multiplied, and by the -veneration in which they were held these texts fixed and stereotyped -the style of Babylonian literature, and the language in which they -were written remained the classical style in the country down to the -Persian conquest. Thus it happens that texts of Rim-agu, Sargon, and -Hammurabi, who were 1000 years before Nebuchadnezzar and Nabonidus, -show the same language as the texts of these later kings, there being -no sensible difference in style to match the long interval between -them,”—precisely as a certain devotional style of writing of our own -day closely resembles the style of the sixteenth century. - -We cannot, then, from the style, determine the age of the original -writings from which the Assyrian tablets were copied. But there are -certain facts which enable us to form an opinion on this point. -Babylonia was conquered about B.C. 1300, by Tugultininip, king of -Assyria. For 250 years before that date a foreign race (called by -Berosus, Arabs) had ruled in Babylonia. There is no evidence of any of -the original Babylonian Genesis tablets being written after the date of -Hammurabi, under whom it is supposed that this race obtained dominion -in Babylonia. Many scholars, indeed, regard Hammurabi as much more -ancient; but none set him later than 1550 B.C. - -Now, before the time of Hammurabi several races of kings reigned, -their reigns ranging over a period of 500 years. They were called -chiefly Kings of Sumir and Akkad—that is, Kings of Upper and Lower -Babylonia. It is believed that before this period,—ranging, say, from -about 2000 B.C. to 1550 B.C. (at least not later, though possibly, -and according to many scholars, probably, far earlier),—the two -divisions of Babylonia were separate monarchies. Thus, evidence -whether any literature was written before or after B.C. 2000, may -be found in the presence or absence of mention, or traces, of this -division of the Babylonian kingdom. Mr. Smith considers, for example, -that two works,—the great Chaldæan work on astrology, and a legend -which he calls “The Exploits of Lubara,”—certainly belong to the -period preceding B.C. 2000. In the former work, the subject of which -specially connects it, as will presently be seen, with the tablet -relating to the creation of the heavenly bodies, Akkad is always -referred to as a separate state. - -Now Mr. Smith finds that the story of the Creation and Fall belongs -to the upper or Akkad division of the country. The Izdubar legends, -containing the story of the Flood, and what Mr. Smith regards as -probably the history of Nimrod, seem to belong to Sumir, the southern -division of Babylonia. He considers the Izdubar legends to have been -written at least as early as B.C. 2000. The story of the Creation -“may not have been committed to writing so early;” but it also is -of great antiquity. And these legends “were traditions before they -were committed to writing, and were common, in some form, to all the -country.” Remembering Mr. Smith’s expressed intention of setting all -dates as late as possible, his endeavour to do this rather than to -establish any system of chronology, we cannot misunderstand the real -drift of his arguments, or the real significance of his conclusion that -the period when the Genesis tablets were originally written extended -from B.C. 2000 to B.C. 1550, or roughly synchronized with the period -from Abraham to Moses, according to the ordinary chronology of our -Bibles. “During this period it appears that traditions of the creation -of the universe, and human history down to the time of Nimrod, existed -parallel to, and in some points identical with, those given in the book -of Genesis.” - -Thus viewing the matter, we recognize the interest of that passage in -the Babylonian Genesis tablets which corresponds with the account in -the book of Genesis respecting the creation of the heavenly bodies. We -find in it the earliest existent record of the origin of astrological -superstitions. It does not express merely the vague belief, which -might be variously interpreted, that the sun and moon and stars were -specially created (after light had been created, after the firmament -had been formed separating the waters above from the waters below, and -after the land had been separated from the water) to be for signs and -for seasons for the inhabitants of the world—that is, of our earth. -It definitely states that those other suns, the stars, were set into -constellation figures for man’s benefit; the planets and the moon next -formed for his use; and the sun set thereafter in the heavens as the -chief among the celestial bodies. - -It runs thus, so far as the fragments have yet been gathered together:— - - -FIFTH TABLET OF CREATION LEGEND. - - 1. It was delightful all that was fixed by the great gods. - - 2. Stars, their appearance [in figures] of animals he arranged, - - 3. To fix the year through the observation of their - constellations, - - 4. Twelve months (or signs) of stars in three rows he arranged, - - 5. From the day when the year commences unto the close. - - 6. He marked the positions of the wandering stars (planets) to - shine in their courses, - - 7. That they may not do injury, and may not trouble any one. - - 8. The positions of the gods Bel and Hea he fixed with him. - - 9. And he opened the great gates in the darkness shrouded, - - 10. The fastenings were strong on the left and right. - - 11. In its mass (_i.e._ the lower chaos) he made a boiling. - - 12. The god Uru (the moon) he caused to rise out, the night he - over shadowed, - - 13. To fix it also for the light of the night until the shining - of the day, - - 14. That the month might not be broken, and in its amount be - regular. - - 15. At the beginning of the month, at the rising of the night, - - 16. His horns are breaking through to shine on the heaven. - - 17. On the seventh day to a circle he begins to swell, - - 18. And stretches towards the dawn further. - - 19. When the god Shamas (the sun) in the horizon of heaven, in - the east, - - 20. . . . formed beautifully and . . . - - 21. . . . . . . to the orbit Shamas was perfected - - 22. . . . . . . . . . the dawn Shamas should change - - 23. . . . . . . . . . . . . going on its path - - 24. . . . . . . . . . . . . . . . giving judgment - - 25. . . . . . . . . . . . . . . . . . . to tame - - 26. . . . . . . . . . . . . . . . . . . . . . a second time - - 27. . . . - - -Of this tablet Smith remarks that it is a typical specimen of the -style of the series, and shows a marked stage in the Creation, the -appointment of the heavenly orbs running parallel to the biblical -account of the fourth day of Creation. It is important to notice -its significance in this respect. We can understand now the meaning -underlying the words, “God said, Let there be lights in the firmament -of the heavens, to divide the day from the night; and let them be for -signs and for seasons, and for days and years.” The order, indeed, -in which the bodies are formed according to the biblical account is -inverted. The greater light—the sun—is made first, to rule the day: -then the lesser light—the moon—to rule the night. These are the -heavenly bodies which in this description rule the day of 24 hours. -The sun may be regarded also as ruling (according to the ancient view, -as according to nature) the seasons and the year. The stars remain as -set in the heaven for signs. “He made the stars also.” “And God set -them”—that is, the sun, moon, and stars—“in the firmament of the -heaven to give light upon the earth, and to rule over the day and over -the night,” and so forth. - -No one can doubt, I conceive, that the biblical account is superior -to the other, both in a scientific and in a literary sense. It states -much less as actually known, and what it does state accords better with -the facts known in the writer’s day. Then, the Babylonian narrative, -though impressive in certain passages, is overloaded with detail. -In both accounts we find the heavenly bodies set in the firmament -by a special creative act, and specially designed for the benefit -of man. And in passing I would observe that the discovery of these -Babylonian inscriptions, however they may be interpreted, and whether -they be regarded as somewhat earlier or somewhat later than the Bible -narrative, appears to dispose finally of the fantastic interpretation -assigned by Hugh Miller and others to the biblical cosmogony, as -corresponding to a series of visions in which the varying aspects -of the world were presented. It has long seemed to me an utterly -untenable proposition that a narrative seemingly intended to describe -definitely a certain series of events should, after being for ages -so interpreted, require now for its correct interpretation to be -regarded as an account of a series of visions. If the explanation were -reconcilable in any way with the words of Genesis, there yet seems -something of profanity in imagining that men’s minds had thus been -played with by a narrative purporting to be of one sort yet in reality -of quite a different character. But whatever possibility there may be -(and it can be but the barest possibility) that the Genesis narrative -admits of the vision interpretation, no one can reasonably attempt to -extend that interpretation to the Babylonian account. So that either -a narrative from which the Genesis account was presumably derived was -certainly intended to describe a series of events, or else a narrative -very nearly as early as the Genesis account, and presumably derived -from it at a time when its true meaning must have been known, presents -the sun, moon, and stars as objects expressly created and set in the -sky after the earth had been formed, and for the special benefit of man -as yet uncreated. - -I am not concerned, however, either to dwell upon this point, or to -insist on any of its consequences. Let us return to the consideration -of the Babylonian narrative as it stands. - -We find twelve constellations or signs of the zodiac are mentioned -as set to fix the year. I am inclined to consider that the preceding -words, “stars, their appearance in figures of animals he arranged,” -relate specially to the stars of the zodiac. The inventor of this -astrogony probably regarded the stars as originally scattered in an -irregular manner over the heavens,—rather as chaotic material from -which constellations might be formed, than as objects separately and -expressly created. Then they were taken and formed into figures of -animals, set in such a way as to fix the year through the observation -of these constellations. It is hardly necessary, perhaps, to remind the -reader that the word zodiac is derived from a Greek word signifying -an animal, the original name of the zone being the zodiacal way, -or the pathway of the animals. Our older navigators called it the -Bestiary.[46] “Twelve months or signs in three rows.” Smith takes the -three rows to mean (i.) the zodiacal signs, (ii.) the constellations -north of the zodiac, and (iii.) the constellations south of the zodiac. -But this does not agree with the words “twelve signs in three rows.” -Possibly the reference is to three circles, two bounding the zodiac -on the north and south respectively, the third central, the ecliptic, -or track of the sun; or the two tropics and the equator may have -been signified. Instead of “twelve signs in three rows,” we should, -probably, read “twelve signs along a triple band.” The description was -written long after astronomical temples were first erected, and as -the designer of a zodiacal dome like that (far more recently) erected -at Denderah would set the twelve zodiacal signs along a band formed -by three parallel circles, marking its central line and its northern -and southern limits, so we can understand the writer of the tablet -presenting the celestial architect as working in the same lines, on a -grander scale; setting the twelve zodiacal signs on the corresponding -triple band in the heavens themselves. - -The next point to be noticed in the Babylonian astrology is the -reference to “wandering stars.” Mr. Smith remarks that the word -_nibir_, thus translated, “is not the usual word for planet, and -there is a star called _Nibir_ near the place where the sun crossed -the boundary between the old and new years, and this star was one of -twelve supposed to be favourable to Babylonia.” “It is evident,” he -proceeds, “from the opening of the inscription on the first tablet of -the Chaldæan astrology and astronomy, that the functions of the stars -were, according to the Babylonians, to act not only as regulators of -the seasons and the year, but also to be used as signs, as in Genesis -i. 14; for in those ages it was generally believed that the heavenly -bodies gave, by their appearance and positions, signs of events which -were coming on the earth.” The two verses relating to Nibir seem to -correspond to no other celestial bodies but planets (unless, perhaps, -to comets). If we regard Nibir as signifying any fixed star, we can -find no significance in the marking of the course of the star Nibir, -that it may do no injury and may not trouble any one. Moreover, as the -fixed stars, the sun, and the moon, are separately described, it seems -unlikely that the planets would be left unnoticed. In the biblical -narrative the reference to the celestial bodies is so short that we -can understand the planets being included in the words, “He made the -stars also.” But in an account so full of detail as that presented -in the Babylonian tablet, the omission of the planets would be very -remarkable. It is also worthy of notice that in Polyhistor’s Babylonian -traditions, recorded by Berosus, we read that “Belus formed the stars, -the sun, the moon, and the five planets.” - -In the tablet narrative the creator of the heavenly bodies is supposed -to be Anu, god of the heavens. This is inferred by Mr. Smith from the -fact “that the God who created the stars, fixed places or habitations -for Bel and Hea with himself in the heavens.” For according to the -Babylonian theogony, the three gods Anu, Bel, and Hea share between -them the divisions of the face of the sky. - -The account of the creation of the moon is perhaps the most -interesting part of the narrative. We see that, according to the -Babylonian philosophy, the earth is regarded as formed from the waters -and resting after its creation above a vast abyss of chaotic water. -We find traces of this old hypothesis in several biblical passages, -as, for instance, in the words of the Third Commandment, “the heaven -above, the earth beneath, and the waters under the earth;” and again -in Proverbs xxx. 4, “Who hath bound the waters in a garment? who -hath established all the ends of the earth?” “The great gates in the -darkness shrouded, the fastenings strong on the left and right,” in the -Babylonian account, refer to the enclosure of the great infernal lake, -so that the waters under the earth might not overwhelm the world. It -is from out the dark ocean beneath the earth that the god Anu calls -the moon into being. He opens the mighty gates shrouded in the nether -darkness, and creates a vast whirlpool in the gloomy ocean; then “at -his bidding, from the turmoil arose the moon like a giant bubble, and -passing through the open gates mounted on its destined way across the -vaults of heaven.” It is strange to reflect that in quite recent times, -at least 4000 years after the Babylonian tablet was written, and who -shall tell how many years after the tradition was first invented?—a -theory of the moon’s origin not unlike the Babylonian hypothesis has -been advanced, despite overwhelming dynamical objections; and a modern -paradoxist has even pointed to the spot beneath the ocean where a -sudden increase of depth indicates that matter was suddenly extruded -long ago, and driven forcibly away from the earth to the orbit along -which that expelled mass—our moon—is now travelling. - -It would have been interesting to have known how the Babylonian tablet -described the creation of Shamas, the sun; though, so far as can be -judged from the fragments above quoted, there was not the same fulness -of detail in this part of the description as in that relating to the -moon. Mr. Smith infers that the Babylonians considered the moon the -more important body, unlike the writer or compiler of the book of -Genesis, who describes the sun as the greater light. It does not seem -to follow very clearly, however, from the tablet record, that the -sun was considered inferior to the moon in importance, and certainly -we cannot imagine that the Babylonians considered the moon a greater -light. The creation of the stars precedes that of the moon, though -manifestly the moon was judged to be more important than the stars. Not -improbably, therefore, the sun, though following the moon in order of -creation, was regarded as the more important orb of the two. In fact, -in the Babylonian as in the (so-called) Mosaic legend of Creation, -the more important members of a series of created bodies are, in some -cases, created last—man last of all orders of animated beings, for -instance. - -If we turn now from the consideration of the Babylonian tradition of -the creation of the heavenly bodies to note how the biblical account -differs from it, not only or chiefly in details, but in general -character, we seem to recognize in the latter a determination to -detach from the celestial orbs the individuality, so to speak, which -the older tradition had given to them. The account in Genesis is not -only simpler, and, in a literary sense, more effective, but it is in -another sense purified. The celestial bodies do not appear in it as -celestial beings. The Babylonian legend is followed only so far as it -can be followed consistently with the avoidance of all that might tempt -to the worship of the sun, moon, and stars. The writer of the book of -Genesis, whether Moses or not, seems certainly to have shared the views -of Moses as to the Sabæanism of the nation from which the children -of Abraham had separated. Moses warned the Israelite,—“Take good -heed unto thyself, lest thou lift up thine eyes unto heaven; and when -thou seest the sun, and the moon, and the stars, even all the host of -heaven, shouldest be driven to worship them, and serve them, which the -Lord thy God hath divided unto all nations under the whole heaven.” So -the writer of Genesis is careful to remove from the tradition which he -follows all that might suggest the individual power and influence of -the heavenly bodies. The stars are to be for signs, but we read nothing -of the power of the wandering stars “to do injury or trouble any one.” -(That is, not in the book of Genesis. In the song of Deborah we find, -though perhaps only in a poetic fashion, the old influences assigned -to the planets, when the singer says that the “stars in their courses -fought against Sisera.” Deborah, however, was a woman, and women have -always been loth and late to give up ancient superstitions.) Again, the -sun and the moon in Genesis are the greater and the lesser lights, not, -as in the Babylonian narrative, the god Shamas and the god Uru. - -We may find a parallel to this treatment of the Babylonian myth in the -treatment by Moses of the observance of the Sabbath, a day of rest -which the Babylonian tablets show to have had, as for other reasons -had been before suspected, an astrological significance. The Jewish -lawgiver does not do away with the observance; in fact, he was probably -powerless to do away with it. At any rate, he suffers the observance -to remain, precisely as the writer of the book of Genesis retains the -Babylonian tradition of the creation of the celestial bodies. But he -is careful to expurgate the Chaldæan observance, just as the writer -of Genesis is careful to expurgate the Babylonian tradition. The week -as a period is no longer associated with astrological superstitions, -nor the Sabbath rest enjoined as a fetish. Both ideas are directly -associated with the monotheistic principle which primarily led to the -separation of the family of Abraham from the rest of the Chaldæan race. -In Babylonia, the method of associating the names of the sun, moon, -and stars with the days, doubtless had its origin. Saturn was the -Sabbath star, as it is still called (Sabbatai) in the Talmud. But, as -Professor Tischendorf told Humboldt, in answer to a question specially -addressed to him on the subject, “there is an entire absence in both -the Old and New Testaments, of any traces of names of week-days taken -from the planets.” The lunar festivals, again, though unquestionably -Sabaistic in their origin, were apparently too thoroughly established -to be discarded by Moses; nay, he was even obliged to permit the -continuance of many observances which suspiciously resembled the old -offerings of sacrifice to the moon as a deity. He had also to continue -the sacrifice of the passover, the origin of which was unmistakably -astronomical,—corresponding in time to the sun’s passage across the -equator, or rather to the first lunar month following and including -that event. But he carefully dissociates both the lunar and the -lunisolar sacrifices from their primary Sabaistic significance. In -fact, the history of early Hebrew legislation, so far as it related to -religion, is the history of a struggle on the part of the lawgivers and -the leaders of opinion against the tendency of the people to revert to -the idolatrous worship of their ancestors and of races closely akin to -them—especially against the tendency to the worship of the sun and -moon and all the host of heaven. - -In the very fact, however, that this contest was maintained, while yet -the Hebrew cosmogony, and in particular the Hebrew astrogony, contains -indubitable evidence of its origin in the poetical myths of older -Babylonia, we find one of the strongest proofs of the influence which -the literature of Babylon, when at the fulness of its development, -exerted upon surrounding nations. This influence is not more clearly -shown even by the fact that nearly 2000 years after the decay of -Babylonian literature, science, and art, a nation like the Assyrians, -engaged in establishing empire rather than in literary and scientific -pursuits, should have been at the pains to obtain copies of many -thousands of the tablet records which formed the libraries of older -Babylonia. In both circumstances we find good reason for hoping that -careful search among Assyrian and Babylonian ruins may not only be -rewarded by the discovery of many other portions of the later Assyrian -library (which was also in some sense a museum), but that other and -earlier copies of the original Babylonian records may be obtained. -For it seems unlikely that works so valuable as to be thought worth -recopying after 1500 or 2000 years, in Assyria, had not been more than -once copied during the interval in Babylonia. “Search in Babylonia,” -says Mr. Smith, “would no doubt yield earlier copies of all these -works, but that search has not yet been instituted, and for the present -we have to be contented with our Assyrian copies. Looking, however, at -the world-wide interest of the subjects, and at the important evidence -which perfect copies of these works would undoubtedly give, there can -be no doubt,” Mr. Smith adds, “that the subject of further search and -discovery will not slumber, and that all as yet known will one day be -superseded by newer texts and fuller and more perfect light.” - - - Printed by BALLANTYNE, HANSON & CO. - Edinburgh & London - - - - -FOOTNOTES - - -[1] More strictly, it plays the same part as a glass screen before a -glowing fire. When the heat of the fire falls on such a screen (through -which light passes readily enough), it is received by the glass, -warming the glass up to a certain point, and the warmed glass emits in -all directions the heat so received; thus scattering over a large space -the rays which, but for the glass, would have fallen directly upon the -objects which the screen is intended to protect. - -[2] The case here imagined is not entirely hypothetical. We examine -Mercury and Venus very nearly under the conditions here imagined; for -we can obtain only spectroscopic evidence respecting the existence -of water on either planet. In the case of Mars we have telescopic -evidence, and no one now doubts that the greenish parts of the planet -are seas and oceans. But Venus and Mercury are never seen under -conditions enabling the observer to determine the colour of various -parts of their discs. - -I may add that a mistake, somewhat analogous to that which I have -described in the cases of an imagined observer of our earth, has -been made by some spectroscopists in the case of the planets Jupiter -and Saturn. In considering the spectroscopic evidence respecting -the condition of these planets’ atmospheres, they have overlooked -the circumstance that we can judge only of the condition of the -outermost and coolest layers, for the lower layers are concealed -from view by the enormous cloud masses, floating, as the telescope -shows, in the atmospheric envelopes of the giant planets. Thus the -German spectroscopist Vögel argues that because in the spectrum -of Jupiter dark lines are seen which are known to belong to the -absorption-spectrum of aqueous vapour, the planet’s surface cannot be -intensely hot. But Jupiter’s absorption-spectrum belongs to layers of -his atmosphere lying far above his surface. We can no more infer the -actual temperature of Jupiter’s surface from the temperature of the -layers which produce his absorption-spectrum, than a visitor who should -view our earth from outer space, observing the low temperature of the -air ten or twelve miles above the sea-level, could infer thence the -actual temperature of the earth’s surface. - -[3] In “Other Worlds than Ours,” I wrote as follows:—“The lines of -hydrogen, which are so well marked in the solar spectrum, are not seen -in the spectrum of Betelgeux. We are not to conclude from this that -hydrogen does not exist in the composition of the star. We know that -certain parts of the solar disc, when examined with the spectroscope, -do not at all times exhibit the hydrogen lines, or may even present -them as bright instead of dark lines. It may well be that in Betelgeux -hydrogen exists under such conditions that the amount of light it sends -forth is nearly equivalent to the amount it absorbs, in which case its -characteristic lines would not be easily discernible. In fact, it is -important to notice generally, that while there can be no mistaking -the positive evidence afforded by the spectroscope as to the existence -of any element in sun or star, the negative evidence supplied by the -absence of particular lines is not to be certainly relied upon.” - -[4] Dr. Draper remarks here in passing, “I do not think that, in -comparisons of the spectra of the elements and sun, enough stress has -been laid on the general appearance of lines apart from their mere -position; in photographic representations this point is very prominent.” - -[5] The word “ignited” may mislead, and indeed is not correctly used -here. The oxygen in the solar atmosphere, like the hydrogen, is simply -glowing with intensity of heat. No process of combustion is taking -place. Ignition, strictly speaking, means the initiation of the process -of combustion, and a substance can only be said to be ignited when it -has been set burning. The word _glowing_ is preferable; or if reference -is made to heat and light combined, then “glowing with intensity of -heat” seems the description most likely to be correctly understood. - -[6] It would be an interesting experiment, which I would specially -recommend to those who, like Dr. Draper, possess instrumental means -specially adapted to the inquiry, to ascertain what variations, if any, -occur in the solar spectrum when (i.) the central part of the disc -alone, and (ii.) the outer part alone, is allowed to transmit light to -the spectroscope. The inquiry seems specially suited to the methods -of spectral photography pursued by Dr. Draper, and by Dr. Huggins, in -this country. Still, I believe interesting results can be obtained even -without these special appliances; and I hope before long to employ my -own telescope in this department of research. - -[7] In 1860, a year of maximum sun-spot frequency, Cambridge won the -University boat-race; the year 1865, of minimum sun-spot frequency, -marked the middle of a long array of Oxford victories; 1872, the next -maximum, marked the middle of a Cambridge series of victories. May we -not anticipate that in 1878, the year of minimum spot frequency, Oxford -will win? [This prediction made in autumn, 1877, was fulfilled.] I -doubt not similar evidence might be obtained about cricket. - -[8] It must be understood that this remark relates only to the theory -that by close scrutiny of the sun a power of predicting weather -peculiarities can be obtained, not to the theory that there may be -a cyclic association between sun-spots and the weather. If this -association exists, yet no scrutiny of the sun can tell us more than -we already know, and it will scarcely be pretended that new solar -observatories could give us any better general idea of the progress of -the great sun-spot period than we obtain from observatories already in -existence, or, indeed, might obtain from the observations of a single -amateur telescopist. - -I think it quite possible that, from the systematic study of -terrestrial relations, the existence of a cyclic association between -the great spot period and terrestrial phenomena may be demonstrated, -instead of being merely surmised, as at present. By the way, it may be -worth noting that a prediction relative to the coming winter [that of -1877–78] has been made on the faith of such association by Professor -Piazzi Smyth. It runs as follows:— - -“Having recently computed the remaining observations of our -earth-thermometers here, and prepared a new projection of all the -observations from their beginning in 1837 to their calamitous close -last year [1876]—results generally confirmatory of those arrived at in -1870 have been obtained, but with more pointed and immediate bearing on -the weather now before us. - -“The chief features undoubtedly deducible for the past thirty-nine -years, after eliminating the more seasonal effects of ordinary summer -and winter, are:— - -“1. Between 1837 and 1876 three great heat-waves, from without, -struck this part of the earth, viz., the first in 1846·5, the second -in 1858·0, and the third in 1868·7. And unless some very complete -alteration in the weather is to take place, the next such visitation -may be looked for in 1879·5, within limits of half a year each way. - -“2. The next feature in magnitude and certainty is that the periods -of minimum temperature, or cold, are not either in, or anywhere near, -the middle time between the crests of those three chronologically -identified heat-waves, but are comparatively close up to them _on -either side_, at a distance of about a year and a half, so that the -next such cold-wave is due at the end of the present year [1877]. - -“This is, perhaps, not an agreeable prospect, especially if political -agitators are at this time moving amongst the colliers, striving to -persuade them to decrease the out-put of coal at every pit’s mouth. -Being, therefore, quite willing, for the general good, to suppose -myself mistaken, I beg to send you a first impression of plate 17 of -the forthcoming volume of observations of this Royal Observatory, and -shall be very happy if you can bring out from the measures recorded -there any more comfortable view for the public at large. - - “PIAZZI SMYTH, - “Astronomer-Royal for Scotland.” - -If this prediction shall be confirmed [this was written in autumn, -1877], it will afford an argument in favour of the existence of the -cyclic relation suggested, but no argument for the endowment of solar -research. Professor Smyth’s observations were not solar but terrestrial. - -[The prediction was not confirmed, the winter of 1877–78 being, on the -contrary, exceptionally mild.] - -[9] The reader unfamiliar with the principles of the telescope may -require to be told that in the ordinary telescope each part of the -object-glass forms a complete image of the object examined. If, when -using an opera-glass (one barrel), a portion of the large glass be -covered, a portion of what had before been visible is concealed. But -this is not the case with a telescope of the ordinary construction. All -that happens when a portion of the object-glass is covered is that the -object appears in some degree less fully illuminated. - -[10] It may be briefly sketched, perhaps, in a note. The force -necessary to draw the earth inwards in such sort as to make her follow -her actual course is proportional to (i) the square of her velocity -directly, and (ii) her distance from the sun inversely. If we increase -our estimate of the earth’s distance from the sun, we, in the same -degree, increase our estimate of her orbital velocity. The square of -this velocity then increases as the square of the estimated distance; -and therefore, the estimated force sunwards is increased as the square -of the distance on account of (i), and diminished as the distance on -account of (ii), and is, therefore, on the whole, increased as the -distance. That is, we now regard the sun’s action as greater at this -greater distance, and in the same degree that the distance is greater; -whereas, if it had been what we before supposed it, it would be less -at the greater distance as the square of the distance (attraction -varying inversely as the square of the distance). Being greater as the -distance, instead of less as the square of the distance, it follows -that our estimate of the sun’s absolute force is now greater as the -cube of the distance. Similarly, if we had diminished our estimate -of the sun’s distance, we should have diminished our estimate of his -absolute power (or mass) as the cube of the distance. But our estimate -of the sun’s volume is also proportional to the cube of his estimated -distance. Hence our estimate of his mass varies as our estimate of his -volume; or, our estimate of his mean density is constant. - -[11] Only very recently an asteroid, Hilda (153rd in order of -detection), has been discovered which travels very much nearer to the -path of Jupiter than to that of Mars—a solitary instance in that -respect. Its distance (the earth’s distance being represented by -unity), is 3·95, Jupiter’s being 5·20, and Mars’s 1·52; its period -falls short of 8 years by only two months, the average period of the -asteroidal family being only about 4½ years. Five others, Cybele, -Freia, Sylvia, Camilla, and Hermione, travel rather nearer to Jupiter -than to Mars; but the remaining 166 travel nearer to Mars, and most of -them much nearer. - -[12] Even this statement is not mathematically exact. If the rails are -straight and parallel, the ratio of approach and recession of an engine -on one line, towards or from an engine on the other, is never quite -equal to the engines’ velocities added together; but the difference -amounts practically to nothing, except when the engines are near each -other. - -[13] I have omitted all reference to details; but in reality the -double battery was automatic, the motion of the observing telescope, -as different colours of the spectrum were brought into view, setting -all the prisms of the double battery into that precise position which -causes them to show best each particular part of the spectrum thus -brought into view. It is rather singular that the first view I ever had -of the solar prominences, was obtained (at Dr. Huggins’s observatory) -with this instrument of my own invention, which also was the first -powerful spectroscope I had ever used or even seen. - -[14] It varies more in some months than in others, as the moon’s orbit -changes in shape under the various perturbing influences to which she -is subject. - -[15] It may seem strange to say that one hundred and twenty years after -the passage of a comet which last passed in 1862, and was then first -discovered, August meteors have been seen. But in reality, as we know -the period of that comet to be about one hundred and thirty years, we -know that the displays of the years 1840, 1841, etc., to 1850, must -have followed the preceding passage by about that interval of time. - -[16] The D line, properly speaking, as originally named by Fraunhofer, -belongs to sodium. The line spoken of above as the sierra D line is -one close by the sodium line, and mistaken for it when first seen in -the spectrum of the coloured prominences as a bright line. It does not -appear as a dark line in the solar spectrum. - -[17] Since this was written, I have learned that Mr. Backhouse, of -Sunderland, announced similar results to those obtained at Dunecht, as -seen a fortnight or so earlier. - -[18] Here no account is taken of the motions of the stars within the -system; such motions must ordinarily be minute compared with the common -motion of the system. - -[19] Eight pictures of nebulæ were exhibited in illustration of this -peculiarity. - -[20] Sir John Herschel long since pointed to the variation of our sun -as a possible cause of such changes of terrestrial climate. - -[21] During these journeys the Atlantic was sounded, and Scoresby’s -estimate of the enormous depth of the Atlantic to the north-west of -Spitzbergen was fully confirmed, the line indicating a depth of more -than two miles. It was found also that Spitzbergen is connected with -Norway by a submarine bank. - -[22] It is far from improbable that a change has taken place in the -climate of the part of the Arctic regions traversed by Koldewey; for -the Dutch seem readily to have found their way much further north two -centuries ago. Indeed, among Captain Koldewey’s results is one which -seems to indicate the occurrence of such a change. The country he -explored was found to have been inhabited. “Numerous huts of Esquimaux -were seen, and various instruments and utensils of primitive form; -but for some reason or other the region seems to have been finally -deserted. The Polar bear reigns supreme on the glaciers, as the walrus -does among the icebergs.” Not improbably the former inhabitants were -forced to leave this region by the gradually increasing cold. - -[23] Dr. Emile Bessels was tried at New York in 1872, on the charge of -having poisoned Captain Hall, but was acquitted. - -[24] The phenomena here described are well worth observing on their -own account, as affording a very instructive and at the same time very -beautiful illustration of wave motions. They can be well seen at many -of our watering-places. The same laws of wave motion can be readily -illustrated also by throwing two stones into a large smooth pool, at -points a few yards apart. The crossing of the two sets of circular -waves produces a wave-net, the meshes of which vary in shape according -to their position. - -[25] It is a pity that men of science so often forget, when addressing -those who are not men of science, or who study other departments than -theirs, that technical terms are out of place. Most people, I take it -are more familiar, on the whole, with eyelids than with _palpebræ_. - -[26] This nautical expression is new to me. Top-gallants—fore, -main, and mizen—I know, and forecastle I know, but the top-gallant -forecastle I do not know. - -[27] The instrument was lent to Mr. Huggins by Mr. W. Spottiswoode. It -has been recently employed successfully at Greenwich. - -[28] Thus in _Christie Johnstone_, written in 1853, when Flucker -Johnstone tells Christie the story of the widow’s sorrows, giving -it word for word, and even throwing in what dramatists call “the -business,” he says, “‘Here ye’ll play your hand like a geraffe.’ -‘Geraffe?’ she says; ‘that’s a beast, I’m thinking.’ ‘Na; it’s the -thing on the hill that makes signals.’ ‘Telegraph, ye fulish goloshen!’ -‘Oo, ay, telegraph! geraffe’s sunnest said for a’.’” “Playing the hand -like a telegraph” would now be as unmeaning as Flucker Johnstone’s -original description. - -[29] Not “to represent the gutta-percha,” as stated in the _Times_ -account of Mr. Muirhead’s invention. The gutta-percha corresponds -to the insulating material of the artificial circuit; viz., the -prepared paper through which the current along the tinfoil strips acts -inductively on the coating of tinfoil. - -[30] I must caution the reader against Fig. 348 in Guillemin’s -_Application of the Physical Forces_, in which the part _c d_ of the -wire is not shown. The two coils are in reality part of a single coil, -divided into two to permit of the bar being bent; and to remove the -part _c d_ is to divide the wire, and, of course, break the current. It -will be seen that _c d_ passes from the remote side of coil _b c_, Fig. -6, to the near side of coil _d e_. If it were taken round the remote -side of the latter coil, the current along this would neutralize the -effect of the current along the other. - -[31] The paper is soaked in dilute ferrocyanide of potassium, and the -passage of the current forms a Prussian blue. - -[32] Sir W. Thomson states, in his altogether excellent article on the -electric telegraph, in Nichol’s _Cyclopædia_, that the invention of -this process is due to Mr. Bakewell. - -[33] It is to be noticed, however, that the recording pointer must -always mark its lines in the same direction, so that, unless a message -is being transmitted at the same time that one is being received (in -which case the oscillations both ways are utilized), the instrument -works only during one-half of each complete double oscillation. - -[34] It seems to me a pity that in the English edition of this work -the usual measures have not been substituted throughout. The book is -not intended or indeed suitable for scientific readers, who alone are -accustomed to the metric system. Other readers do not care to have a -little sum in reduction to go through at each numerical statement. - -[35] Hanno’s _Periplus_—the voyage of Hanno, chief of the -Carthaginians, round the parts of Libya, beyond the Pillars of -Hercules, the narrative of which he posted up in the Temple of Kronos. - -[36] I may mention one which occurred within my own experience. A -mastiff of mine, some years ago, was eating from a plate full of broken -meat. It was his custom to bury the large pieces when there was more -than he could get through. While he was burying a large piece, a cat -ran off with a small fragment. The moment he returned to the plate he -missed this, and, seeing no one else near the plate, he, in his own -way, accused a little daughter of mine (some two or three years old) -of the theft. Looking fiercely at her, he growled his suspicions, and -would not suffer her to escape from the corner where his plate stood -until I dragged him away by his chain. Nor did he for some time forget -the wrong which he supposed she had done him, but always growled when -she came near his house. - -[37] It may be suggested, in passing, that the association which -has been commonly noticed between prominent eyeballs and command -of language (phrenologists place the organ of language, in their -unscientific phraseology, behind the eyeballs) may be related in -some degree to the circumstance that in gradually emerging from the -condition of an arboreal creature the anthropoid ape would not only -cease to derive advantage from sunken eyes, but would be benefited by -the possession of more prominent eyeballs. The increasing prominence -of the eyeballs would thus be a change directly associated with the -gradual advance of the animal to a condition in which, associating -into larger and larger companies and becoming more and more dependent -on mutual assistance and discipline, they would require the use of a -gradually extending series of vocal signs to indicate their wants and -wishes to each other. - -[38] The word hypothesis is too often used as though it were synonymous -with theory, so that Newton’s famous saying, “Hypotheses non fingo” -has come to be regarded by many as though it expressed an objection on -Newton’s part against the formation of theories. This would have been -strange indeed in the author of the noblest theory yet propounded by -man in matters scientific. Newton indicates his meaning plainly enough, -in the very paragraph in which the above expression occurs, defining an -hypothesis as an opinion not based on phenomena. - -[39] I find it somewhat difficult to understand clearly Mr. Mivart’s -own position with reference to the general theory of evolution. He -certainly is an evolutionist, and as certainly he considers natural -selection combined with the tendency to variation (as ordinarily -understood) insufficient to account for the existence of the various -forms of animal and vegetable existence. He supplies the missing factor -in “an innate law imposed on nature, by which new and definite species, -under definite conditions, emerged from a latent and potential being -into actual and manifest existence;” and, so far as can be judged, -he considers that the origin of man himself is an instance of the -operation of this law. - -[40] The Middle Tertiary period—the Tertiary, which includes the -Eocene, Miocene, and Pliocene periods, being the latest of the three -great periods recognized by geologists as preceding the present -era, which includes the entire history of man as at present known -geologically. - -[41] Closely following in this respect his illustrious namesake -Roger, who writes, in the sixth chapter of his _Opus Majus_, “_Sine -experientia nihil sufficienter sciri potest._” - -[42] Fibrine and albumen are identical in composition. _Caseine_, which -is the coagulable portion of milk, is composed in the same manner. The -chief distinction between the three substances consists in their mode -of coagulation; fibrine coagulating spontaneously, albumen under the -action of heat, and caseine by the action of acetic acid. - -[43] To this article of the Professor’s faith decided objection must be -taken, however. - -[44] Those whose custom it is to regard all theorizing respecting -the circumstances revealed by observation as unscientific, may read -with profit an extremely speculative passage in Newton’s _Principia_ -relating to the probable drying up of the earth in future ages. “As the -seas,” he says, “are absolutely necessary to the constitution of our -earth, that from them the sun, by its heat, may exhale a sufficient -quantity of vapours, which, being gathered together into clouds, may -drop down in rain, for watering of the earth, and for the production -and nourishment of vegetables; or being condensed with cold on the tops -of mountains (as some philosophers with reason judge), may run down in -springs and rivers; so for the conservation of the seas and fluids of -the planets, comets seem to be required, that, from their exhalations -and vapours condensed, the wastes of the planetary fluids spent upon -vegetation and putrefaction, and converted into dry earth, may be -ultimately supplied and made up; for all vegetables entirely derive -their growths from fluids, and afterwards, in great measure, are turned -into dry earth by putrefaction; and a sort of slime is always found -to settle at the bottom of putrefied fluids; and hence it is that the -bulk of the solid earth is continually increased; and the fluids, if -they are not supplied from without, must be in a continual decrease, -and quite fail at last. I suspect, moreover, that it is chiefly from -the comets that spirit comes which is indeed the smallest but the most -subtle and useful part of our air, and so much required to sustain the -life of all things with us.” - -[45] See my “Science Byways,” pp. 244, 245. - -[46] The following passage from Admiral Smyth’s Bedford Catalogue is -worth noticing in this connection:—“We find that both the Chinese and -the Japanese had a zodiac consisting of animals, as _zodiacs_ needs -must, among which they placed a tiger, a peacock, a cat, an alligator, -a duck, an ape, a hog, a rat, and what not. Animals also formed the -_Via Solis_ of the Kirghis, the Mongols, the Persians, the Mantshus, -and the ancient Turks; and the Spanish monks in the army of Cortes -found that the Mexicans had a zodiac with strange creatures in the -departments. Such a striking similitude is assuredly indicative of a -common origin, since the coincidences are too exact in most instances -to be the effect of chance; but where this origin is to be fixed has -been the subject of interminable discussions, and learning, ignorance, -sagacity, and prejudice have long been in battle array against each -other. Diodorus Siculus considers it to be Babylonian, but Bishop -Warburton, somewhat dogmatically tells us, ‘Brute worship gave rise to -the Egyptian asterisms prior to the time of Moses.’” There is now, of -course, very little reason for questioning that Egyptian astronomy was -borrowed from Babylon. - - - - -Transcriber’s Notes - - -Cover created by Transcriber and placed in the Public Domain. - -Punctuation, hyphenation, and spelling were made consistent when a -predominant preference was found in this book; otherwise they were not -changed. - -Simple typographical errors were corrected; occasional unbalanced -quotation marks retained. - -Ambiguous hyphens at the ends of lines were retained. - -Some ditto marks have been replaced by the actual text. - -Page 83: In the illustration, “O” should be “C”. - -Page 171: There is no obvious closing quotation mark to match the -opening mark at “of most unusual age and thickness”. - -Page 192: “Divided even between the ocean” may be a misprint for -“evenly”. - -Page 197: No matching closing quotation mark for the opening mark at -“the small bright spot”. - -Page 222: Transcriber added an opening quotation mark at “Down his -back” to match the closing mark after “He was seen by every one on -board.” - -Page 230: No matching closing quotation mark for the opening mark at “a -whale of large size”. - -Page 302: Transcriber added an opening quotation mark at “About fifty -years ago” to match the closing mark after “fed himself with the other.” - -Page 372: No matching opening quotation mark for the closing mark after -“its lower extremity.” - -Page 385: No matching closing quotation mark for the opening mark at -“sweeps off from”. - - - - - -End of Project Gutenberg's Pleasant Ways in Science, by Richard A. 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display: block; text-align: center;} -} - </style> - </head> - -<body> - - -<pre> - -Project Gutenberg's Pleasant Ways in Science, by Richard A. Proctor - -This eBook is for the use of anyone anywhere in the United States and most -other parts of the world 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. If you are not located in the United States, you'll have -to check the laws of the country where you are located before using this ebook. - -Title: Pleasant Ways in Science - -Author: Richard A. Proctor - -Release Date: March 17, 2017 [EBook #54376] - -Language: English - -Character set encoding: UTF-8 - -*** START OF THIS PROJECT GUTENBERG EBOOK PLEASANT WAYS IN SCIENCE *** - - - - -Produced by Chris Curnow, Charlie Howard, and the Online -Distributed Proofreading Team at http://www.pgdp.net (This -file was produced from images generously made available -by The Internet Archive) - - - - - - -</pre> - - -<div class="transnote covernote"> -<p class="center">Transcriber’s Note: -Cover created by Transcriber and placed in the Public Domain.</p> -</div> - -<h1>PLEASANT WAYS IN SCIENCE.</h1> - -<hr /> - -<h2>WORKS BY RICHARD A. PROCTOR.</h2> - -<blockquote class="hang narrow larger"> - -<p>LIGHT SCIENCE FOR LEISURE -HOURS: Familiar Essays on Scientific -Subjects. Crown 8vo, 3<i>s.</i> 6<i>d.</i></p> - -<p>THE ORBS AROUND US: A Series -of Essays on the Moon and Planets, -Meteors and Comets. With Charts and -Diagrams. Crown 8vo, 3<i>s.</i> 6<i>d.</i></p> - -<p>OTHER WORLDS THAN OURS: -The Plurality of Worlds Studied under -the Light of Recent Scientific Researches. -With 14 Illustrations. Crown -8vo, 3<i>s.</i> 6<i>d.</i></p> - -<p>OTHER SUNS THAN OURS: A -Series of Essays on Suns—Old, Young, -and Dead. With other Science Gleanings. -Two Essays on Whist, and Correspondence -with Sir John Herschel. With -9 Star Maps and Diagrams. Cr. 8vo, -3<i>s.</i> 6<i>d.</i></p> - -<p>THE MOON: Her Motions, Aspects, -Scenery, and Physical Condition. With -Plates, Charts, Woodcuts, &c. Crown -8vo, 3<i>s.</i> 6<i>d.</i></p> - -<p>UNIVERSE OF STARS: Presenting -Researches into and New Views respecting -the Constitution of the Heavens. -With 22 Charts and 22 Diagrams. 8vo, -10<i>s.</i> 6<i>d.</i></p> - -<p>LARGER STAR ATLAS for the -Library, in 12 Circular Maps, with Introduction -and 2 Index Pages. Folio, -15<i>s.</i>; or Maps only, 12<i>s.</i> 6<i>d.</i></p> - -<p>NEW STAR ATLAS for the Library, -the School, and the Observatory, in 12 -Circular Maps. Crown 8vo, 5<i>s.</i></p> - -<p>HALF-HOURS WITH THE -STARS: A Plain and Easy Guide to -the Knowledge of the Constellations. -Showing in 12 Maps the position of the -principal Star Groups night after night -throughout the Year. With Introduction -and a separate Explanation of each -Map. True for every Year. 4to, 3<i>s.</i> net.</p> - -<p>HALF-HOURS WITH THE TELESCOPE: -A Popular Guide to the Use -of the Telescope as a means of Amusement -and Instruction. With 7 Plates. -Fcp. 8vo, 2<i>s.</i> 6<i>d.</i></p> - -<p>THE STARS IN THEIR SEASONS: -An Easy Guide to a Knowledge of the -Star Groups, in 12 Large Maps. Imperial -8vo, 5<i>s.</i></p> - -<p>THE SOUTHERN SKIES: A Plain -and Easy Guide to the Constellations of -the Southern Hemisphere. Showing in -12 Maps the position of the principal -Star Groups night after night throughout -the Year. With an Introduction -and a separate Explanation of each -Map. True for every Year. 4to, 5<i>s.</i></p> - -<p>STAR PRIMER: Showing the Starry -Sky Week by Week, in 24 Hourly Maps. -Crown 4to, 2<i>s.</i> 6<i>d.</i></p> - -<p>ROUGH WAYS MADE SMOOTH: -Familiar Essays on Scientific Subjects. -Crown 8vo, 3<i>s.</i> 6<i>d.</i></p> - -<p>OUR PLACE AMONG INFINITIES: -A Series of Essays contrasting -our Little Abode in Space and Time -with the Infinities around us. Crown -8vo, 3<i>s.</i> 6<i>d.</i></p> - -<p>THE EXPANSE OF HEAVEN: -Essays on the Wonders of the Firmament. -Crown 8vo, 3s. 6<i>d.</i></p> - -<p>THE GREAT PYRAMID: OBSERVATORY, -TOMB, AND TEMPLE. -With Illustrations. Crown 8vo, 5<i>s.</i></p> - -<p>PLEASANT WAYS IN SCIENCE. -Crown 8vo, 3<i>s.</i> 6<i>d.</i></p> - -<p>MYTHS AND MARVELS OF ASTRONOMY. -Crown 8vo, 3<i>s.</i> 6<i>d.</i></p> - -<p>NATURE STUDIES. By <span class="smcap">Grant -Allen</span>, <span class="smcap">A. Wilson</span>, <span class="smcap">T. Foster</span>, <span class="smcap">E. -Clodd</span>, and <span class="smcap">R. A. Proctor</span>. Crown -8vo, 3<i>s.</i> 6<i>d.</i></p> - -<p>LEISURE READINGS. By <span class="smcap">E. -Clodd</span>, <span class="smcap">A. Wilson</span>, <span class="smcap">T. Foster</span>, <span class="smcap">A. C. -Ranyard</span>, and <span class="smcap">R. A. Proctor</span>. Crown -8vo, 5<i>s.</i> Cheap Edition, 3<i>s.</i> 6<i>d.</i></p> - -<p>STRENGTH: How to Get Strong -and Keep Strong. With Chapters on -Rowing and Swimming, Fat, Age, and -the Waist. With 9 Illustrations. Crown -8vo, 2<i>s.</i></p> - -<p>CHANCE AND LUCK: A Discussion -of the Laws of Luck, Coincidences, -Wagers, Lotteries, and the Fallacies of -Gambling, &c. Crown 8vo, 2<i>s.</i> 6<i>d.</i></p> - -<p>HOW TO PLAY WHIST: With the -Laws and Etiquette of Whist. Crown -8vo, 3<i>s.</i> net.</p> - -<p>HOME WHIST: An Easy Guide to -Correct Play. 16mo, 1<i>s.</i></p></blockquote> - -<hr class="short" /> -<p class="p0 larger center"><span class="smcap">London</span>: LONGMANS, GREEN, & CO.</p> - -<hr /> - -<p class="newpage p4 center vspace xxlarge gesperrt wspace"> -PLEASANT WAYS<br /> -<span class="smaller">IN SCIENCE</span></p> - -<p class="p2 center larger vspace"><span class="xsmall">BY</span><br /> -<span class="wspace gesperrt">RICHARD A. PROCTOR</span></p> - -<p class="p1 center small vspace">AUTHOR OF<br /> -“ROUGH WAYS MADE SMOOTH,” “THE EXPANSE OF HEAVEN,” “OUR PLACE<br /> -AMONG INFINITIES,” “MYTHS AND MARVELS OF ASTRONOMY,”<br /> -ETC. ETC.</p> - -<p class="p2 center"><i>NEW IMPRESSION</i></p> - -<p class="p2 center vspace wspace"><span class="gesperrt larger">LONGMANS, GREEN, AND CO.</span><br /> -39 PATERNOSTER ROW, LONDON<br /> -NEW YORK AND BOMBAY<br /> -1905 -</p> - -<hr /> - -<div class="chapter"> -<h2><a id="CONTENTS"></a>CONTENTS.</h2> -</div> - -<table id="toc" summary="Contents"> - <tr class="small"> - <td> </td> - <td class="tdr nopad">PAGE</td></tr> - <tr> - <td class="tdl"><span class="smcap">Oxygen in the Sun</span></td> - <td class="tdr"><a href="#OXYGEN_IN_THE_SUN">1</a></td></tr> - <tr> - <td class="tdl"><span class="smcap">Sun-Spot, Storm, and Famine</span></td> - <td class="tdr"><a href="#SUN-SPOT_STORM_AND_FAMINE">28</a></td></tr> - <tr> - <td class="tdl"><span class="smcap">New Ways of Measuring the Sun’s Distance</span></td> - <td class="tdr"><a href="#NEW_WAYS_OF_MEASURING_THE_SUNS_DISTANCE">56</a></td></tr> - <tr> - <td class="tdl"><span class="smcap">Drifting Light Waves</span></td> - <td class="tdr"><a href="#DRIFTING_LIGHT-WAVES">77</a></td></tr> - <tr> - <td class="tdl"><span class="smcap">The New Star which faded into Star-Mist</span></td> - <td class="tdr"><a href="#THE_NEW_STAR_WHICH_FADED_INTO_STAR-MIST">106</a></td></tr> - <tr> - <td class="tdl"><span class="smcap">Star-Grouping, Star-Drift, and Star-Mist</span></td> - <td class="tdr"><a href="#STAR-GROUPING_STAR-DRIFT_AND_STAR-MIST">136</a></td></tr> - <tr> - <td class="tdl"><span class="smcap">Mallet’s Theory of Volcanoes</span></td> - <td class="tdr"><a href="#MALLETS_THEORY_OF_VOLCANOES">151</a></td></tr> - <tr> - <td class="tdl"><span class="smcap">Towards the North Pole</span></td> - <td class="tdr"><a href="#TOWARDS_THE_NORTH_POLE">156</a></td></tr> - <tr> - <td class="tdl"><span class="smcap">A Mighty Sea-Wave</span></td> - <td class="tdr"><a href="#A_MIGHTY_SEA-WAVE">178</a></td></tr> - <tr> - <td class="tdl"><span class="smcap">Strange Sea Creatures</span></td> - <td class="tdr"><a href="#STRANGE_SEA_CREATURES">199</a></td></tr> - <tr> - <td class="tdl"><span class="smcap">On some Marvels in Telegraphy</span></td> - <td class="tdr"><a href="#ON_SOME_MARVELS_IN_TELEGRAPHY">232</a></td></tr> - <tr> - <td class="tdl"><span class="smcap">The Phonograph, or Voice-Recorder</span></td> - <td class="tdr"><a href="#THE_PHONOGRAPH_OR_VOICE-RECORDER">274</a></td></tr> - <tr> - <td class="tdl"><span class="smcap">The Gorilla and other Apes</span></td> - <td class="tdr"><a href="#THE_GORILLA_AND_OTHER_APES">296</a></td></tr> - <tr> - <td class="tdl"><span class="smcap">The Use and Abuse of Food</span></td> - <td class="tdr"><a href="#THE_USE_AND_ABUSE_OF_FOOD">330</a></td></tr> - <tr> - <td class="tdl"><span class="smcap">Ozone</span></td> - <td class="tdr"><a href="#OZONE">347</a></td></tr> - <tr> - <td class="tdl"><span class="smcap">Dew</span></td> - <td class="tdr"><a href="#DEW">357</a></td></tr> - <tr> - <td class="tdl"><span class="smcap">The Levelling Power of Rain</span></td> - <td class="tdr"><a href="#THE_LEVELLING_POWER_OF_RAIN">367</a></td></tr> - <tr> - <td class="tdl"><span class="smcap">Ancient Babylonian Astrogony</span></td> - <td class="tdr"><a href="#ANCIENT_BABYLONIAN_ASTROGONY">388</a></td></tr> -</table> - -<hr /> - -<p><span class="pagenum"><a id="Page_vii">vii</a></span></p> - -<div class="chapter"> -<h2><a id="PREFACE"></a>PREFACE.</h2> -</div> - -<p class="in0">It is very necessary that all who desire to become -really proficient in any department of science should -follow the beaten track, toiling more or less painfully -over the difficult parts of the high road which -is their only trustworthy approach to the learning -they desire to attain. But there are many who -wish to learn about scientific discoveries without this -special labour, for which some have, perhaps, little -taste, while many have scant leisure. My purpose -in the present work, as in my “Light Science for -Leisure Hours,” the “Myths and Marvels of Astronomy,” -the “Borderland of Science,” and “Science -Byways,” has been to provide paths of easy access -to the knowledge of some of the more interesting -discoveries, researches, or inquiries of the science of -the day. I wish it to be distinctly understood that -my purpose is to interest rather than to instruct, in -the strict sense of the word. But I may add that it -seems to me even more necessary to be cautious, and -accurate in such a work as the present than in -advanced treatises. For in a scientific work the -reasoning which accompanies the statements of fact<span class="pagenum"><a id="Page_viii">viii</a></span> -affords the means of testing and sometimes of correcting -such statements. In a work like the present, -where explanation and description take the place of -reasoning, there is no such check. For this reason I -have been very careful in the accounts which I have -given of the subjects here dealt with. I have been -particularly careful not to present, as established -truths, such views as are at present only matters -of opinion.</p> - -<p>The essays in the present volume are taken chiefly -from the <cite>Contemporary Review</cite>, the <cite>Gentleman’s Magazine</cite>, -the <cite>Cornhill Magazine</cite>, <cite>Belgravia</cite>, and <cite>Chambers’ -Journal</cite>. The sixth, however, presents the substance -(and official report) of a lecture which I delivered -at the Royal Institution in May, 1870. It was then -that I first publicly enunciated the views respecting -the stellar universe which I afterwards more fully -stated in my “Universe of Stars.” The same views -have also been submitted to the Paris Academy of -Science, as the results of his own investigations, by -M. Flammarion, in words which read almost like -translations of passages in the above-mentioned -essay.</p> - -<p class="sigright"> -RICHARD A. PROCTOR. -</p> - -<hr /> - -<p><span class="pagenum"><a id="Page_1">1</a></span></p> - -<div class="chapter"> -<h2><span class="larger wspace"><a id="PLEASANT_WAYS_IN_SCIENCE"></a>PLEASANT WAYS IN SCIENCE.</span></h2> -</div> - -<h2 class="nobreak p4"><a id="OXYGEN_IN_THE_SUN"></a><i>OXYGEN IN THE SUN.</i></h2> - -<p class="in0">The most promising result of solar research since Kirchhoff -in 1859 interpreted the dark lines of the sun’s spectrum -has recently been announced from America. Interesting -in itself, the discovery just made is doubly interesting in -what it seems to promise in the future. Just as Kirchhoff’s -great discovery, that a certain double dark line in the solar -spectrum is due to the vapour of sodium in the sun’s atmosphere, -was but the first of a long series of results which the -spectroscopic analysis of the sun was to reveal, so the discovery -just announced that a certain important gas—the -oxygen present in our air and the chief chemical constituent -of water—shows its presence in the sun by bright -lines instead of dark, will in all probability turn out to be -but the firstfruits of a new method of examining the solar -spectrum. As its author, Dr. Henry Draper, of New York, -remarks, further investigation in the direction he has pursued -will lead to the discovery of other elements in the sun, but -it was not “proper to conceal, for the sake of personal -advantage, the principle on which such researches are to -be conducted.” It may well happen, though I anticipate -otherwise, that by thus at once describing his method of -observation, Dr. Draper may enable others to add to the<span class="pagenum"><a id="Page_2">2</a></span> -list of known solar elements some which yet remain to be -detected; but if Dr. Draper should thus have added but -one element to that list, he will ever be regarded as the -physicist to whose acumen the method was due by which all -were detected, and to whom, therefore, the chief credit of -their discovery must certainly be attributed.</p> - -<p>I propose briefly to consider the circumstances which -preceded the great discovery which it is now my pleasing -duty to describe, in order that the reader may the more -readily follow the remarks by which I shall endeavour to -indicate some of the results which seem to follow from the -discovery, as well as the line along which, in my opinion, -the new method may most hopefully be followed.</p> - -<p>It is generally known that what is called the spectroscopic -method of analyzing the sun’s substance had its origin -in Kirchhoff’s interpretation of the dark lines in the solar -spectrum. Until 1859 these dark lines had not been -supposed to have any special significance, or rather it had -not been supposed that their significance, whatever it might -be, could be interpreted. A physicist of some eminence -spoke of these phenomena in 1858 in a tone which ought -by the way seldom to be adopted by the man of science. -“The phenomena defy, as we have seen,” he said, “all -attempts hitherto to reduce them within empirical laws, and -no complete explanation or theory of them is possible. -All that theory can be expected to do is this—it may explain -how dark lines of any sort may arise within the spectrum.” -Kirchhoff, in 1859, showed not only how dark lines of any -sort may appear, but how and why they do appear, and -precisely what they mean. He found that the dark lines -of the solar spectrum are due to the vapours of various -elements in the sun’s atmosphere, and that the nature of -such elements may be determined from the observed position -of the dark lines. Thus when iron is raised by the -passage of the electric spark to so intense a degree of heat -that it is vaporized, the light of the glowing vapour of iron -is found to give a multitude of bright lines along the whole<span class="pagenum"><a id="Page_3">3</a></span> -length of the spectrum—that is, some red, some orange, -some yellow, and so on. In the solar spectrum corresponding -dark lines are found along the whole length of the -spectrum—that is, some in the red, some in the orange, -yellow, etc., and precisely in those parts of these various -spectral regions which the bright lines of glowing iron would -occupy. Multitudes of other dark lines exist of course in -the solar spectrum. But those corresponding to the bright -lines of glowing iron are unquestionably there. They are -by no means lost in the multitude, as might be expected; -but, owing to the peculiarity of their arrangement, strength, -etc., they are perfectly recognizable as the iron lines reversed, -that is, dark instead of bright. Kirchhoff’s researches -showed how this is to be interpreted. It means that the -vapour of iron exists in the atmosphere of the sun, glowing -necessarily with an intensely bright light; <em>but</em>, being cooler -(however intensely hot) than the general mass of the sun -within, the iron vapour absorbs more light than it emits, -and the result is that the iron lines, instead of appearing -bright, as they would if the iron vapour alone were shining, -appear relatively dark on the bright rainbow-tinted background -of the solar spectrum.</p> - -<p>Thus was it shown that in the atmosphere of the sun -there is the glowing vapour of the familiar metal, iron; and -in like manner other metals, and one element (hydrogen) -which is not ordinarily regarded as a metal, were shown to -be present in the sun’s atmosphere. In saying that they -are present in the sun’s atmosphere, I am, in point of fact, -saying that they are present in the sun; for the solar atmosphere -is, in fact, the outer part of the sun himself, since a -very large part, if not by far the greater part, of the sun’s -mass must be vaporous. But no other elements, except the -metals iron, sodium, barium, calcium, magnesium, aluminium, -manganese, chromium, cobalt, nickel, zinc, copper, -and titanium, and the element hydrogen, were shown to be -present in the sun, by this method of observing directly the -solar dark lines. In passing, I may note that there are<span class="pagenum"><a id="Page_4">4</a></span> -reasons for regarding hydrogen as a metallic element, strange -though the idea may seem to those who regard hardness, -brightness, malleability, ductility, plasticity, and the like, -as the characteristic properties of metals, and necessarily -fail to comprehend how a gas far rarer, under the same -conditions, than the air we breathe, and which cannot -possibly be malleable, ductile, or the like, can conceivably -be regarded as a metal. But there is in reality no necessary -connection between any one of the above properties and -the metallic nature; many of the fifty-five metals are wanting -in all of these properties; nor is there any reason why, as -we have in mercury a metal which at ordinary temperatures -is a liquid, so we might have in hydrogen a metal -which, at all obtainable temperatures, and under all obtainable -conditions of pressure, is gaseous. It was shown by -the late Professor Graham (aided in his researches most -effectively by Dr. Chandler Roberts) that hydrogen will -enter into such combination with the metal palladium that -it may be regarded as forming, for the time, with the palladium, -an alloy; and as alloys can only be regarded as -compounds of two or more metals, the inference is that -hydrogen is in reality a metallic element.</p> - -<p>Fourteen only of the elements known to us, or less than -a quarter of the total number, were thus found to be present -in the sun’s constitution; and of these all were metals, if -we regard hydrogen as metallic. Neither gold nor silver -shows any trace of its presence, nor can any sign be seen -of platinum, lead, and mercury. But, most remarkable of -all, and most perplexing, was the absence of all trace of -oxygen and nitrogen, two gases which could not be supposed -wanting in the substance of the great ruling centre of the -planetary system. It might well be believed, indeed, that -none of the five metals just named are absent from the sun, -and indeed that every one of the forty metals not recognized -by the spectroscopic method nevertheless exists in the sun. -For according to the nebular hypothesis of the origin of our -solar system, the sun might be expected to contain all the<span class="pagenum"><a id="Page_5">5</a></span> -elements which exist in our earth. Some of these elements -might indeed escape discovery, because existing only in -small quantities; and others (as platinum, gold, and lead, -for example), because but a small portion of their vaporous -substance rose above the level of that glowing surface which -is called the photosphere. But that oxygen, which constitutes -so large a portion of the solid, liquid, and vaporous -mass of our earth, should not exist in enormous quantities, -and its presence be very readily discernable, seemed amazing -indeed. Nitrogen, also, might well be expected to be -recognizable in the sun. Carbon, again, is so important a -constituent of the earth, that we should expect to discover -clear traces of its existence in the sun. In less degree, -similar considerations apply to sulphur, boron, silicon, and -the other non-metallic elements.</p> - -<p>It was not supposed, however, by any one at all competent -to form an opinion on the subject, that oxygen, nitrogen, -and carbon are absent from the sun. It was perceived -that an element might exist in enormous quantities in the -substance of the sun, and yet fail to give any evidence of its -presence, or only give such evidence as might readily escape -recognition. If we remember how the dark lines are really -caused, we shall perceive that this is so. A glowing vapour -in the atmosphere of the sun absorbs rays of the same colour -as it emits. If then, it is cooler than the glowing mass of -the sun which it enwraps, and if, notwithstanding the heat -received from this mass, it remains cooler, then it suffers -none of those rays to pass earthwards.<a id="FNanchor_1" href="#Footnote_1" class="fnanchor">1</a> It emits rays of the -same kind (that is, of the same <em>colour</em>) itself, but, being cooler, -the rays thus coming from it are feebler; or, to speak more<span class="pagenum"><a id="Page_6">6</a></span> -correctly, the ethereal waves thus originated are feebler than -those of the same order which <em>would</em> have travelled earthwards -from the sun but for the interposed screen of vapour. -Hence the corresponding parts of the solar spectrum are less -brilliant, and contrasted with the rainbow-tinted streak of -light, on which they lie as on a background, they appear dark.</p> - -<p>In order, then, that any element may be detected by its -dark lines, it is necessary that it should lie as a vaporous -screen between the more intensely heated mass of the sun -and the eye of the observer on earth. It must then form an -enclosing envelope cooler than the sun within it. Or rather, -some part of the vapour must be thus situated. For enormous -masses of the vapour might be within the photospheric -surface of the sun at a much higher temperature, which yet, -being enclosed in the cooler vaporous shell of the same -substance, would not be able to send its light rays earthwards. -One may compare the state of things, so far as that particular -element is concerned, to what is presented in the case of -a metallic globe cooled on the outside but intensely hot -within. The cool outside of such a globe is what determines -the light and heat received from it, so long as the more -heated mass within has not yet (by conduction) warmed the -exterior shell. So in the case of a vapour permeating the -entire mass, perhaps, of the sun, and at as high a temperature -as the sun everywhere except on the outside: it is the -temperature of the outermost part of such a vaporous mass -which determines the intensity of the rays received from it—or -in other words, determines whether the corresponding -parts of the spectrum shall be darker or not than the rest of -the spectrum. If the vapour does not rise above the photosphere -of the sun in sufficient quantity to exercise a recognizable -absorptive effect, its presence in the sun will not be -indicated by any dark lines.</p> - -<p>I dwell here on the question of quantity, which is sometimes -overlooked in considering the spectroscopic evidence -of the sun’s condition, but is in reality a very important -factor in determining the nature of the evidence relating to<span class="pagenum"><a id="Page_7">7</a></span> -each element in the solar mass. In some cases, the quantity -of a material necessary to give unmistakable spectroscopic -evidence is singularly small; insomuch that new elements, -as thallium, cæsium, rubidium, and gallium, have been actually -first recognized by their spectral lines when existing in -such minute quantities in the substances examined as to give -no other trace whatever of their existence. But it would be -altogether a mistake to suppose that some element existing -in exceedingly small quantities, or, more correctly, existing in -the form of an exceedingly rare vapour in the sun’s atmosphere, -would be detected by means of its dark lines, or <em>by any other -method depending on the study of the solar spectrum</em>. When we -place a small portion of some substance in the space between -the carbon points of an electric lamp, and volatilize that -substance in the voltaic arc, we obtain a spectrum including -all the bright lines of the various elements contained in the -substance; and if some element is contained in it in exceedingly -small quantity, we may yet perceive its distinctive -bright lines among the others (many of them far brighter) -belonging to the elements present in greater quantities. But -if we have (for example) a great mass of molten iron, the -rainbow-tinted spectrum of whose light we examine from a -great distance, and if a small quantity of sodium, or other substance -which vaporizes at moderate temperatures, be cast into -the molten iron so that the vapour of the added element -presently rises above the glowing surface of the iron, no trace -of the presence of this vapour would be shown in the spectrum -observed from a distance. The part of the spectrum -where the dark lines of sodium usually appear would, undoubtedly, -be less brilliant than before, in the same sense -that the sun may be said to be less brilliant when the air is -in the least degree moist than when it is perfectly dry; but -the loss of brilliancy is as utterly imperceptible in the one -case as it is in the other. In like manner, a vapour might -exist in the atmosphere of the sun (above the photosphere, -that is), of whose presence not a trace would be afforded in -the spectroscope, for the simple reason that the absorptive<span class="pagenum"><a id="Page_8">8</a></span> -action of the vapour, though exerted to reduce the brightness -of particular solar rays or tints, would not affect those rays -sufficiently for the spectroscopist to recognize any diminution -of their lustre.</p> - -<p>There is another consideration, which, so far as I know, -has not hitherto received much attention, but should certainly -be taken into account in the attempt to interpret the -real meaning of the solar spectrum. Some of the metals -which are vaporized by the sun’s heat below the photosphere -may become liquid or even solid at or near the level of the -photosphere. Even though the heat at the level of the -photosphere may be such that, under ordinary conditions of -pressure and so forth, such metals would be vaporous, the -enormous pressure which must exist not far below the level -of the photosphere may make the heat necessary for complete -vaporization far greater than the actual heat at that -level. In that case the vapour will in part condense into -liquid globules, or, if the heat is considerably less than is -necessary to keep the substance in the form of vapour, then -it may in part be solidified, the tiny globules of liquid metal -becoming tiny crystals of solid metal. We see both conditions -fulfilled within the limits of our own air in the case of -the vapour of water. Low down the water is present in the -air (ordinarily) in the form of pure vapour; at a higher level -the vapour is condensed by cold into liquid drops forming -visible clouds (cumulus clouds), and yet higher, where the -cold is still greater, the minute water-drops turn into ice-crystals, -forming those light fleecy clouds called cirrus clouds -by the meteorologist. Now true clouds of either sort may -exist in the solar atmosphere even above that photospheric -level which forms the boundary of the sun we see. It may -be said that the spectroscope, applied to examine matter -outside the photosphere, has given evidence only of vaporous -cloud masses. The ruddy prominences which tower tens of -thousands of miles above the surface of the sun, and the sierra -(or as it is sometimes unclassically called, the chromosphere) -which covers usually the whole of the photosphere to a<span class="pagenum"><a id="Page_9">9</a></span> -depth of about eight thousand miles, show only, under spectroscopic -scrutiny, the bright lines indicating gaseity. But -though this is perfectly true, it is also true that we have not -here a particle of evidence to show that clouds of liquid -particles, and of tiny crystals, may not float over the sun’s -surface, or even that the ruddy clouds shown by the spectroscope -to shine with light indicative of gaseity may not also -contain liquid and crystalline particles. For in point of fact, -the very principle on which our recognition of the bright -lines depends involves the inference that matter whose light -would <em>not</em> be resolved into bright lines would not be recognizable -at all. The bright lines are seen, because by means -of a spectroscope we can throw them far apart, without -reducing their lustre, while the background of rainbow-tinted -spectrum has its various portions similarly thrown further -apart and correspondingly weakened. One may compare -the process (the comparison, I believe, has not hitherto been -employed) to the dilution of a dense liquid in which solid -masses have been floating: the more we increase the quantity -of the liquid in diluting it with water, the more transparent -it becomes, but the solid masses in it are not changed, -so that we only have to dilute the liquid sufficiently to see -these masses. <em>But</em> if there were in the interstices of the -solid masses particles of some substance which dissolved in -the water, we should not recognize the presence of this substance -by any increase in its visibility; for the very same -process which thinned the liquid would thin this soluble -substance in the same degree. In like manner, by dispersing -and correspondingly weakening the sun’s light more and -more, we can recognize the light of the gaseous matter in the -prominences, for this is not weakened; but if the prominences -also contain matter in the solid or liquid form (that is, drops -or crystals), the spectroscopic method will not indicate the -presence of such matter, for the spectrum of matter of this -sort will be weakened by dispersion in precisely the same -degree that the solar spectrum itself is weakened.</p> - -<p>It is easy to see how the evidence of the presence of any<span class="pagenum"><a id="Page_10">10</a></span> -element which behaved in this way would be weakened, if -we consider what would happen in the case of our own -earth, according as the air were simply moist but without -clouds, or loaded with cumulus masses but without cirrus -clouds, or loaded with cirrus clouds. For although there is -not in the case of the earth a central glowing mass like the -sun’s, on whose rainbow-tinted spectrum the dark lines -caused by the absorptive action of our atmosphere could -be seen by the inhabitant of some distant planet studying -the earth from without, yet the sun’s light reflected from -the surface of the earth plays in reality a similar part. -It does not give a simple rainbow-tinted spectrum; for, being -sunlight, it shows all the dark lines of the solar spectrum: -but the addition of new dark lines to these, in consequence -of the absorptive action of the earth’s atmosphere, could -very readily be determined. In fact, we do thus recognize -in the spectra of Mars, Venus, and other planets, the -presence of aqueous vapour in their atmosphere, despite -the fact that our own air, containing also aqueous vapour, -naturally renders so much the more difficult the detection -of that vapour in the atmosphere of remote planets necessarily -seen through our own air. Now, a distant observer -examining the light of our own earth on a day when, though -the air was moist, there were no clouds, would have ample -evidence of the presence of the vapour of water; for the -light which he examined would have gone twice through our -earth’s atmosphere, from its outermost thinnest parts to the -densest layers close to the surface, then back again through -the entire thickness of the air. But if the air were heavily -laden with cumulus clouds (without any cirrus clouds at -a higher layer), although <em>we</em> should know that there was -abundant moisture in the air, and indeed much more moisture -then there had been when there had been no clouds, our -imagined observer would either perceive no traces at all of -this moisture, or he would perceive traces so much fainter -than when the air was clear that he would be apt to infer that -the air was either quite dry, or at least very much drier than<span class="pagenum"><a id="Page_11">11</a></span> -it had been in that case. For the light which he would -receive from the earth would not in this case have passed -through the entire depth of moisture-laden air twice, but -twice only through that portion of the air which lay above -the clouds, at whose surface the sun’s light would be reflected. -The whole of the moisture-laden layer of the air would be -snugly concealed under the cloud-layer, and would exercise -no absorptive action whatever on the light which the remote -observer would examine. If from the upper surface of the -layer of cumulus clouds aqueous vapour rose still higher, -and were converted in the cold upper regions of the -atmosphere into clouds of ice-crystals, the distant observer -would have still less chance of recognizing the presence of -moisture in our atmosphere. For the layer of air between -the cumulus clouds and the cirrus clouds would be unable to -exert any absorptive action on the light which reached the -observer. All such light would come to him after reflection -from the layer of cirrus clouds. He would be apt to infer -that there was no moisture at all in the air of our planet, at -the very time when in fact there was so much moisture that -not one layer only, but two layers of clouds enveloped the -earth, the innermost layer consisting of particles of liquid -water, the outermost of particles of frozen water. Using the -words ice, water, and steam, to represent the solid, liquid, -and vaporous states of water, we may fairly say that ice and -water, by hiding steam, would persuade the remote observer -that there was no water at all on the earth—at least if he -trusted solely to the spectroscopic evidence then obtained.<a id="FNanchor_2" href="#Footnote_2" class="fnanchor">2</a></p> - -<p><span class="pagenum"><a id="Page_12">12</a></span> -We might in like manner fail to obtain any spectroscopic -evidence of the presence of particular elements in the -sun, because they do not exist in sufficient quantity in the -vaporous form in those outer layers which the spectroscope -can alone deal with.</p> - -<p>In passing, I must note a circumstance in which some of -those who have dealt with this special part of the spectroscopic -evidence have erred. It is true in one sense that -some elements may be of such a nature that their vapours -cannot rise so high in the solar atmosphere as those of -other elements. But it must not be supposed that the -denser vapours seek a lower level, the lighter vapours -rising higher. According to the known laws of gaseous -diffusion, a gas or vapour diffuses itself throughout a space -occupied by another gas or several other gases, in the same -way as though the space were not occupied at all. If we -introduce into a vessel full of common air a quantity of -carbonic acid gas (I follow the older and more familiar -nomenclature), this gas, although of much higher specific -gravity than either oxygen or nitrogen, does not take its -place at the bottom of the vessel, but so diffuses itself that -the air of the upper part of the vessel contains exactly the -same quantity of carbonic acid gas as the air of the lower<span class="pagenum"><a id="Page_13">13</a></span> -part. Similarly, if hydrogen is introduced, it does not seek -the upper part of the vessel, but diffuses itself uniformly -throughout the vessel. If we enclose the carbonic acid gas -in a light silken covering, and the hydrogen in another (at -the same pressure as the air in the vessel) one little balloon -will sink and the other will rise; but this is simply because -diffusion is prevented. It may be asked how this agrees -with what I have said above, that some elements may not -exist in sufficient quantity or in suitable condition above the -sun’s photospheric level to give any spectroscope evidence -of their nature. As to quantity, indeed, the answer is -obvious: if there is only a small quantity of any given element -in the entire mass of the sun, only a very small quantity can -under any circumstances exist outside the photosphere. As -regards condition, it must be remembered that the vessel of -my illustrative case was supposed to contain air at a given -temperature and pressure throughout. If the vessel was so -large that in different parts of it the temperature and pressure -were different, the diffusion would, indeed, still be perfect, -because at all ordinary temperatures and pressures hydrogen -and carbonic acid gas remain gaseous. But if the vapour -introduced is of such a nature that at moderate temperatures -and pressures it condenses, wholly or in part, or liquefies, -the diffusion will not take place with the same uniformity. -We need not go further for illustration than to the case of -our own atmosphere as it actually exists. The vapour of -water spreads uniformly through each layer of the atmosphere -which is at such a temperature and pressure as to -permit of such diffusion; but where the temperature is too -low for complete diffusion (at the actual pressure) the -aqueous vapour is condensed into visible cloud, diffusion -being checked at this point as at an impassable boundary. -In the case of the sun, as in the case of our own earth, it is -not the density of an element when in a vaporous form -which limits its diffusion, but the value of the temperature -at which its vapour at given pressure condenses into liquid -particles. It is in this way only that any separation can be<span class="pagenum"><a id="Page_14">14</a></span> -effected between the various elements which exist in the -sun’s substance. A separation of this sort is unquestionably -competent to modify the spectroscopic evidence respecting -different elements. But it would be a mistake to -suppose that any such separation could occur as has been -imagined by some—a separation causing in remote times the -planets supposed to have been thrown off by the sun to be -rarest on the outskirts of the solar system and densest close -to the sun. The small densities of the outer family of -planets, as compared with the densities of the so-called -terrestrial planets, must certainly be otherwise explained.</p> - -<p>But undoubtedly the chief circumstance likely to operate -in veiling the existence of important constituents of the -solar mass must be that which has so long prevented spectroscopists -from detecting the presence of oxygen in the -sun. An element may exist in such a condition, either over -particular parts of the photosphere, or over the entire surface -of the sun, that instead of causing dark lines in the -solar spectrum it may produce bright lines. Such lines may -be conspicuous, or they may be so little brighter than the -background of the spectrum as to be scarcely perceptible -or quite imperceptible.</p> - -<p>In passing, I would notice that this interpretation of the -want of all spectroscopic evidence of the presence of oxygen, -carbon, and other elements in the sun, is not an <i xml:lang="la" lang="la">ex post -facto</i> explanation. As will presently appear, it is now absolutely -certain that oxygen, though really existing, and -doubtless, in enormous quantities, in the sun, has been concealed -from recognition in this way. But that this might -be so was perceived long ago. I myself, in the first edition -of my treatise on “The Sun,” pointed out, in 1870, with -special reference to nitrogen and oxygen, that an element -“may be in a condition enabling it to radiate as much light -as it absorbs, or else very little more or very little less; so -that it either obliterates all signs of its existence, or else -gives lines so little brighter or darker than the surrounding -parts of the spectrum that we can detect no trace of its<span class="pagenum"><a id="Page_15">15</a></span> -existence.” I had still earlier given a similar explanation -of the absence of all spectroscopic evidence of hydrogen in -the case of the bright star Betelgeux.<a id="FNanchor_3" href="#Footnote_3" class="fnanchor">3</a></p> - -<p>Let us more closely consider the significance of what we -learn from the spectral evidence respecting the gas hydrogen. -We know that when the total light of the sun is dealt -with, the presence of hydrogen is constantly indicated by -dark lines. In other words, regarding the sun as a whole, -hydrogen constantly reduces the emission of rays of those -special tints which correspond to the light of this element. -When we examine the light of other suns than ours, we find -that in many cases, probably in by far the greater number -of cases, hydrogen acts a similar part. But not in every -case. In the spectra of some stars, notably in those of -Betelgeux and Alpha Herculis, the lines of hydrogen are -not visible at all; while in yet others, as Gamma Cassiopeiæ, -the middle star of the five which form the straggling -W of this constellation, the lines of hydrogen show bright -upon the relatively dark background of the spectrum. When -we examine closely the sun himself, we find that although -his light as a whole gives a spectrum in which the lines of -hydrogen appear dark, the light of particular parts of his -surface, if separately examined, occasionally shows the -hydrogen lines bright as in the spectrum of Gamma Cassiopeiæ, -while sometimes the light of particular parts gives,<span class="pagenum"><a id="Page_16">16</a></span> -like the light of Betelgeux, no spectroscopic evidence whatever -of the presence of hydrogen. Manifestly, if the whole -surface of the sun were in the condition of the portions -which give bright hydrogen lines, the spectrum of the sun -would resemble that of Gamma Cassiopeiæ; while if the -whole surface were in the condition of those parts which -show no lines of hydrogen, the spectrum of the sun would -resemble that of Betelgeux. Now if there were any reason -for supposing that the parts of the sun which give no lines -of hydrogen are those from which the hydrogen has been -temporarily removed in some way, we might reasonably -infer that in the stars whose spectra show no hydrogen lines -there is no hydrogen. But the fact that the hydrogen lines -are sometimes seen bright renders this supposition untenable. -For we cannot suppose that the lines of hydrogen -change from dark to bright or from bright to dark (both -which changes certainly take place) without passing through -a stage in which they are neither bright nor dark; in other -words, we are compelled to assume that there is an intermediate -condition in which the hydrogen lines, though -really existent, are invisible because they are of precisely -the same lustre as the adjacent parts of the spectrum. -Hence the evanescence of the hydrogen lines affords no -reason for supposing that hydrogen has become even reduced -in quantity where the lines are not seen. And therefore -it follows that the invisibility of the hydrogen lines in -the spectrum of Betelgeux is no proof that hydrogen does -not exist in that star in quantities resembling those in which -it is present in the sun. And this, being demonstrated in -the case of one gas, must be regarded as at least probable -in the case of other gases. Wherefore the absence of the -lines of oxygen from the spectrum of any star affords no -sufficient reason for believing that oxygen is not present in -that star, or that it may not be as plentifully present as -hydrogen, or even far more plentifully present.</p> - -<p>There are other considerations which have to be taken -into account, as well in dealing with the difficulty arising<span class="pagenum"><a id="Page_17">17</a></span> -from the absence of the lines of particular elements from -the solar spectrum as in weighing the extremely important -discovery which has just been effected by Dr. H. Draper.</p> - -<p>I would specially call attention now to a point which I -thus presented seven years ago:—“The great difficulty of -interpreting the results of the spectroscopic analysis of the -sun arises from the circumstance that we have no means of -learning whence that part of the light comes which gives -the continuous spectrum. When we recognize certain dark -lines, we know certainly that the corresponding element -exists in the gaseous form at a lower temperature than the -substance which gives the continuous spectrum. But as -regards that continuous spectrum itself we can form no such -exact opinion.” It might, for instance, have its origin in -glowing liquid or solid matter; but it might also be compounded -of many spectra, each containing a large number -of bands, the bands of one spectrum filling up the spaces -which would be left dark between the bands of another -spectrum, and so on until the entire range from the extreme -visible red to the extreme visible violet were occupied by -what appeared as a continuous rainbow-tinted streak. “We -have, in fact, in the sun,” as I pointed out, “a vast agglomeration -of elements, subject to two giant influences, producing -in some sort opposing effects—viz., a temperature -far surpassing any we can form any conception of, and a -pressure (throughout nearly the whole of the sun’s globe) -which is perhaps even more disproportionate to the phenomena -of our experience. Each known element would -be vaporized by the solar temperature at known pressures; -each (there can be little question) would be solidified by the -vast pressures, did these arise at known temperatures. Now -whether, under these circumstances, the laws of gaseous -diffusion prevail where the elements <em>are</em> gaseous in the solar -globe; whether, where liquid matter exists it is in general -bounded in a definite manner from the neighbouring gaseous -matter; whether any elements at all are solid, and if so -under what conditions their solidity is maintained and the<span class="pagenum"><a id="Page_18">18</a></span> -limits of the solid matter defined—all these are questions -which <em>must</em> be answered before we can form a satisfactory -idea of the solar constitution; yet they are questions which -we have at present no means of answering.” Again, we -require to know whether any process resembling combustion -can under any circumstances take place in the sun’s globe. -If we could assume that some general resemblance exists -between the processes at work upon the sun and those we -are acquainted with, we might imagine that the various elements -ordinarily exist in the sun’s globe in the gaseous form -(chiefly) to certain levels, to others chiefly in the liquid -form, and to yet others chiefly in the solid form. But even -then that part of each element which is gaseous may exist -in two forms, having widely different spectra (in reality in -five, but I consider only the extreme forms). The light -of one part is capable of giving characteristic spectra of -lines or bands (which will be different according to pressure -and may appear either dark or bright); that of the other -is capable of giving a spectrum nearly or quite continuous.</p> - -<p>It will be seen that Dr. H. Draper’s discovery supplies -an answer to one of the questions, or rather to one of the -sets of questions, thus indicated. I give his discovery as -far as possible in his own words.</p> - -<p>“<em>Oxygen discloses itself</em>,” he says, “<em>by bright lines or -bands in the solar spectrum</em>, and does not give dark absorption-lines -like the metals. We must therefore change our -theory of the solar spectrum, and no longer regard it merely -as a continuous spectrum with certain rays absorbed by a -layer of ignited metallic vapours, but as having also bright -lines and bands superposed on the background of continuous -spectrum. Such a conception not only opens the way -to the discovery of others of the non-metals, sulphur, phosphorus, -selenium, chlorine, bromine, iodine, fluorine, carbon, -etc., but also may account for some of the so-called dark -lines, by regarding them as intervals between bright lines. -It must be distinctly understood that in speaking of the -solar spectrum here, I do not mean the spectrum of any<span class="pagenum"><a id="Page_19">19</a></span> -limited area upon the disc or margin of the sun, but the -spectrum of light from the whole disc.”</p> - -<p>In support of the important statement here advanced, -Dr. Draper submits a photograph of part of the solar spectrum -with a comparison spectrum of air, and also with some -of the lines of iron and aluminium. The photograph itself, -a copy of which, kindly sent to me by Dr. Draper, lies before -me as I write, fully bears out Dr. Draper’s statement. It is -absolutely free from handwork or retouching, except that -reference letters have been added in the negative. It shows -the part of the solar spectrum between the well-known -Fraunhofer lines G and H, of which G (an iron line) lies in -the indigo, and H (a line of hydrogen) in the violet, so that -the portion photographed belongs to that region of the -spectrum whose chemical or actinic energy is strongest. -Adjacent to this lies the photograph of the air lines, showing -nine or ten well-defined oxygen lines or groups of lines, and -two nitrogen bands. The exact agreement of the two -spectra in position is indicated by the coincidence of bright -lines of iron and aluminium included in the air spectrum -with the dark lines of the same elements in the solar spectrum. -“No close observation,” as Dr. Draper truly remarks, -“is needed to demonstrate to even the most casual observer” -(of this photograph) “that the oxygen lines are found in the -sun as bright lines.” There is in particular one quadruple -group of oxygen lines in the air spectrum, the coincidence -of which with a group of bright lines in the solar spectrum -is unmistakable.</p> - -<p>“This oxygen group alone is almost sufficient,” says Dr. -Draper, “to prove the presence of oxygen in the sun, for not -only does each of the four components have a representative -in the solar group, but the relative strength and the general -aspect of the lines in each case is similar.<a id="FNanchor_4" href="#Footnote_4" class="fnanchor">4</a> I shall not<span class="pagenum"><a id="Page_20">20</a></span> -attempt at this time,” he proceeds, “to give a complete list -of the oxygen lines, ... and it will be noticed that some -lines in the air spectrum which have bright anologues in the -sun are not marked with the symbol of oxygen. This is -because there has not yet been an opportunity to make the -necessary detailed comparisons. In order to be certain that -a line belongs to oxygen, I have compared, under various -pressures, the spectra of air, oxygen, nitrogen, carbonic acid, -carburetted hydrogen, hydrogen, and cyanogen.</p> - -<p>“As to the spectrum of nitrogen and the existence of -this element in the sun there is not yet certainty. Nevertheless, -even by comparing the diffused nitrogen lines of this -particular photograph, in which nitrogen has been sacrificed -to get the best effect for oxygen, the character of the evidence -appears. There is a triple band somewhat diffused in the -photograph belonging to nitrogen, which has its appropriate -representative in the solar spectrum, and another band of -nitrogen is similarly represented.” Dr. Draper states that -“in another photograph a heavy nitrogen line which in the -present one lies opposite an insufficiently exposed part of -the solar spectrum, corresponds to a comparison band in the -sun.”</p> - -<p>But one of the most remarkable points in Dr. Draper’s -paper is what he tells us respecting the visibility of these -lines in the spectrum itself. They fall, as I have mentioned, -in a part of the spectrum where the actinic energy is great -but the luminosity small; in fact, while this part of the -spectrum is the very strongest for photography, it is close to -the region of the visible spectrum,</p> - -<div class="poem-container"> -<div class="poem"><div class="stanza"> -<span class="iq">“Where the last gleamings of refracted light<br /></span> -<span class="i0">Die in the fainting violet away.”<br /></span> -</div></div> -</div> - -<p class="in0">It is therefore to be expected that those, if any, of the bright -lines of oxygen, will be least favourably shown for direct -vision, and most favourably for what might almost be called -photographic vision, where we see what photography records -for us. Yet Dr. Draper states that these bright lines of<span class="pagenum"><a id="Page_21">21</a></span> -oxygen can be readily seen. “The bright lines of oxygen -in the spectrum of the solar disc have not been hitherto perceived, -probably from the fact that in eye-observation bright -lines on a less bright background do not make the impression -on the mind that dark lines do. When attention is called -to their presence they are readily enough seen, even without -the aid of a reference spectrum. The photograph, however, -brings them into greater prominence.” As the lines of -oxygen are not confined to the indigo and violet, we may -fairly hope that the bright lines in other parts of the spectrum -of oxygen may be detected in the spectrum of the sun, now -that spectroscopists know that bright lines and not dark -lines are to be looked for.</p> - -<p>Dr. Draper remarks that from purely theoretic considerations -derived from terrestrial chemistry, and the nebular -hypothesis, the presence of oxygen in the sun might have -been strongly suspected; for this element is currently stated -to form eight-ninths of the water of the globe, one-third of -the crust of the earth, and one-fifth of the air, and should -therefore probably be a large constituent of every member -of the solar system. On the other hand, the discovery of -oxygen, and probably other non-metals, in the sun gives -increased strength to the nebular hypothesis, because to -many persons the absence of this important group has presented -a considerable difficulty. I have already remarked -on the circumstance that we cannot, according to the known -laws of gaseous diffusion, accept the reasoning of those who -have endeavoured to explain the small density of the outer -planets by the supposition that the lighter gases were left -behind by the great contracting nebulous mass, out of which, -on the nebular hypothesis, the solar system is supposed to -have been formed. It is important to notice, now, that if -on the one hand we find in the community of structure -between the sun and our earth, as confirmed by the discovery -of oxygen and nitrogen in the sun, evidence favouring -the theory according to which all the members of that system -were formed out of what was originally a single mass, we do<span class="pagenum"><a id="Page_22">22</a></span> -not find evidence against the theory (as those who have -advanced the explanation above referred to may be disposed -to imagine) in the recognition in the sun’s mass of enormous -quantities of one of these elements which, according to their -view, ought to be found chiefly in the outer members of the -solar system. If those who believe in the nebular hypothesis -(generally, that is, for many of the details of the hypothesis -as advanced by Laplace are entirely untenable in the present -position of physical science) had accepted the attempted -explanation of the supposed absence of the non-metallic -elements in the sun, they would now find themselves in a -somewhat awkward position. They would, in fact, be almost -bound logically to reject the nebular hypothesis, seeing that -one of the asserted results of the formation of our system, -according to that hypothesis, would have been disproved. -But so far as I know no supporter of the nebular hypothesis -possessing sufficient knowledge of astronomical facts and -physical laws to render his opinion of any weight, has ever -given in his adhesion to the unsatisfactory explanation -referred to.</p> - -<p>The view which I have long entertained respecting the -growth of the solar system—viz., that it had its origin, not -in contraction only or chiefly, but in combined processes of -contraction and accretion—seems to me to be very strongly -confirmed by Dr. Draper’s discovery. This would not be -the place for a full discussion of the reasons on which this -opinion is based. But I may remark that I believe no one who -applies the laws of physics, <em>as at present known</em>, to the theory -of the simple contraction of a great nebulous mass formerly -extending far beyond the orbit of Neptune, till, when planet -after planet had been thrown off, the sun was left in his -present form and condition in the centre, will fail to perceive -enormous difficulties in the hypothesis, or to recognize in -Dr. Draper’s discovery a difficulty added to those affecting -the hypothesis <em>so presented</em>. Has it ever occurred, I often -wonder, to those who glibly quote the nebular theory as -originally propounded, to inquire how far some of the processes<span class="pagenum"><a id="Page_23">23</a></span> -suggested by Laplace are in accordance with the now -known laws of physics? To begin with, the original nebulous -mass extending to a distance exceeding the earth’s distance -from the sun more than thirty times (this being only the -distance of Neptune), if we assign to it a degree of compression -making its axial diameter half its equatorial diameter, -would have had a volume exceeding the sun’s (roughly) -about 120,000,000,000 times, and in this degree its mean -density would have been less than the sun’s. This would -correspond to a density equal (roughly) to about one-400,000th -part of the density of hydrogen gas at atmospheric -pressure. To suppose that a great mass of matter, having -this exceedingly small mean density, and extending to a -distance of three or four thousand millions of miles from its -centre, could under any circumstances rotate as a whole, -or behave in other respects after the fashion attributed to the -gaseous embryon of the solar system in ordinary descriptions -of the nebular hypothesis, is altogether inconsistent with -correct ideas of physical and dynamical laws. It is absolutely -a necessity of any nebular hypothesis of the solar -system, that from the very beginning a central nucleus and -subordinate nuclei should form in it, and grow according to -the results of the motions (at first to all intents and purposes -independent) of its various parts. Granting this state of -things, we arrive, by considering the combined effects of -accretion and contraction, at a process of development -according fully as well as that ordinarily described with the -general relations described by Laplace, and accounting also -(in a general way) for certain peculiarities which are in no -degree explained by the ordinary theory. Amongst these -may specially be noted the arrangement and distribution of -the masses within the solar system, and the fact that so far -as spectroscopic evidence enables us to judge, a general -similarity of structure exists throughout the whole of the -system.</p> - -<p>Inquiring as to the significance of his discovery, Dr. -Draper remarks that it seems rather difficult “at first sight<span class="pagenum"><a id="Page_24">24</a></span> -to believe that an ignited<a id="FNanchor_5" href="#Footnote_5" class="fnanchor">5</a> gas in the solar atmosphere -should not be indicated by dark lines in the solar spectrum, -and should appear not to act under the law, ‘a gas when -ignited absorbs rays of the same refrangibility as those it -emits.’ But, in fact, the substances hitherto investigated -in the sun are really metallic vapours, hydrogen probably -coming under that rule. The non-metals obviously may -behave differently. It is easy to speculate on the causes of -such behaviour; and it may be suggested that the reason of -the non-appearance of a dark line may be that the intensity -of the light from a great thickness of ignited oxygen overpowers -the effect of the photosphere, just as, if a person -were to look at a candle-flame through a yard thickness of -sodium vapour, he would only see bright sodium lines, and -no dark absorption.”</p> - -<p>The reasoning here is not altogether satisfactory (or -else is not quite correctly expressed). In the first place, -the difficulty dealt with has no real existence. The law -that a gas when glowing absorbs rays of the same refrangibility -as it emits, does not imply that a gas between a -source of light and the observer will show its presence by -spectroscopic dark lines. A gas so placed <em>does</em> receive from -the source of light rays corresponding to those which it -emits itself, if it is cooler than the source of light; and it -absorbs them, being in fact heated by means of them, though -the gain of temperature may be dissipated as fast as received; -but if the gas is hotter, it emits more of those rays than it -absorbs, and will make its presence known by its bright lines. -This is not a matter of speculation, but of experiment. On<span class="pagenum"><a id="Page_25">25</a></span> -the other hand, the experiment suggested by Dr. Draper -would not have the effect he supposes, if it were correctly -made. Doubtless, if the light from a considerable area of -dully glowing sodium vapour were received by the spectroscope -at the same time as the light of a candle-flame seen -through the sodium vapour, the light of the sodium vapour -overcoming that of the candle-flame would indicate its -presence by bright lines; but if light were received only -from that portion of the sodium vapour which lay between -the eye and the candle-flame, then I apprehend that the dark -lines of sodium would not only be seen, but would be conspicuous -by their darkness.</p> - -<p>It is in no cavilling spirit that I indicate what appears to -me erroneous in a portion of Dr. Draper’s reasoning on his -great discovery. The entire significance of the discovery -depends on the meaning attached to it, and therefore it is -most desirable to ascertain what this meaning really is. -There can be no doubt, I think, that we are to look for the -true interpretation of the brightness of the oxygen lines in -the higher temperature of the oxygen, not in the great depth -of oxygen above the photospheric level. The oxygen which -produces these bright lines need not necessarily be above -the photosphere at all. (In fact, I may remark here that -Dr. Draper, in a communication addressed to myself, mentions -that he has found no traces at present of oxygen above -the photosphere, though I had not this circumstance in my -thoughts in reasoning down to the conclusion that the part -of the oxygen effective in showing these bright lines lies -probably below the visible photosphere.) Of course, if the -photosphere were really composed of glowing solid and -liquid matter, or of masses of gas so compressed and so -intensely heated as to give a continuous spectrum, no gas -existing below the photosphere could send its light through, -nor could its presence, therefore, be indicated in any spectroscopic -manner. But the investigations which have been -made into the structure of the photosphere as revealed by -the telescope, and in particular the observations made by<span class="pagenum"><a id="Page_26">26</a></span> -Professor Langley, of the Alleghany Observatory, show that -we have not in the photosphere a definite bounding envelope -of the sun, but receive light from many different depths -below that spherical surface, 425,000 miles from the sun’s -centre, which we call the photospheric level. We receive -more light from the centre of the solar disc, I feel satisfied, -not solely because the absorptive layer through which we -there see the sun is shallower, but partly, and perhaps chiefly, -because we there receive light from some of the interior and -more intensely heated parts of the sun.<a id="FNanchor_6" href="#Footnote_6" class="fnanchor">6</a> Should this prove -to be the case, it may be found possible to do what heretofore -astronomers have supposed to be impossible—to ascertain -in some degree how far and in what way the constitution -of the sun varies below the photosphere, which, so far as -ordinary telescopic observation is concerned, seems to present -a limit below which researches cannot be pursued.</p> - -<p>I hope we shall soon obtain news from Dr. Huggins’s -Observatory that the oxygen lines have been photographed, -and possibly the bright lines of other elements recognized in -the solar spectrum. Mr. Lockyer also, we may hope, will -exercise that observing skill which enabled him early to -recognize the presence of bright hydrogen lines in the spectrum -of portions of the sun’s surface, to examine that -spectrum for other bright lines.</p> - -<p>I do not remember any time within the last twenty years -when the prospects of fresh solar discoveries seemed more -hopeful than they do at present. The interest which has of -late years been drawn to the subject has had the effect of<span class="pagenum"><a id="Page_27">27</a></span> -enlisting fresh recruits in the work of observation, and many -of these may before long be heard of as among those who -have employed Dr. Draper’s method successfully.</p> - -<p>But I would specially call attention to the interest which -attaches to Dr. Draper’s discovery and to the researches -likely to follow from it, in connection with a branch of research -which is becoming more and more closely connected -year by year with solar investigations—I mean stellar spectroscopy. -We have seen the stars divided into orders -according to their constitution. We recognize evidence -tending to show that these various orders depend in part -upon age—not absolute but relative age. There are among -the suns which people space some younger by far than our -sun, others far older, and some in a late stage of stellar -decrepitude. Whether as yet spectroscopists have perfectly -succeeded in classifying these stellar orders in such sort that -the connection between a star’s spectrum and the star’s age -can be at once determined, may be doubtful. But certainly -there are reasons for hoping that before long this will be -done. Amongst the stars, and (strange to say) among -celestial objects which are not stars, there are suns in every -conceivable stage of development, from embryon masses -not as yet justly to be regarded as suns, to masses which -have ceased to fulfil the duties of suns. Among the more -pressing duties of spectroscopic analysis at the present time -is the proper classification of these various orders of stars. -Whensoever that task shall have been accomplished, strong -light, I venture to predict, will be thrown on our sun’s present -condition, as well as on his past history, and on that future -fate upon which depends the future of our earth.</p> - -<hr /> - -<p><span class="pagenum"><a id="Page_28">28</a></span></p> - -<div class="chapter"> -<h2><a id="SUN-SPOT_STORM_AND_FAMINE"></a><i>SUN-SPOT, STORM, AND FAMINE.</i></h2> -</div> - -<p class="in0">During the last five or six years a section of the scientific -world has been exercised with the question how far the condition -of the sun’s surface with regard to spots affects our -earth’s condition as to weather, and therefore as to those -circumstances which are more or less dependent on weather. -Unfortunately, the question thus raised has not presented -itself alone, but in company with another not so strictly -scientific, in fact, regarded by most men of science as closely -related to personal considerations—the question, namely, -whether certain indicated persons should or should not be -commissioned to undertake the inquiry into the scientific -problem. But the scientific question itself ought not to be -less interesting to us because it has been associated, correctly -or not, with the wants and wishes of those who advocate -the endowment of science. I propose here to consider the -subject in its scientific aspect only, and apart from any bias -suggested by the appeals which have been addressed to the -administrators of the public funds.</p> - -<p>It is hardly necessary to point out, in the first place, that -all the phenomena of weather are directly referable to the -sun as their governing cause. His rays poured upon our air -cause the more important atmospheric currents directly. Indirectly -they cause modifications of these currents, because -where they fall on water or on moist surfaces they raise -aqueous vapour into the air, which, when it returns to the -liquid form as cloud, gives up to the surrounding air the -heat which had originally vaporized the water. In these<span class="pagenum"><a id="Page_29">29</a></span> -ways, directly or indirectly, various degrees of pressure and -temperature are brought about in the atmospheric envelope -of the earth, and, speaking generally, all air currents, from the -gentlest zephyr to the fiercest tornado, are the movements -by which the equilibrium of the air is restored. Like other -movements tending to restore equilibrium, the atmospheric -motions are oscillatory. Precisely as when a spring has been -bent one way, it flies not back only, but beyond the mean -position, till it is almost equally bent the other way, so the -current of air which rushes in towards a place of unduly -diminished pressure does more than restore the mean -pressure, so that presently a return current carries off the -excess of air thus carried in. We may say, indeed, that the -mean pressure at any place scarcely ever exists, and when it -exists for a time the resulting calm is of short duration. Just -as the usual condition of the sea surface is one of disturbance, -greater or less, so the usual condition of the air at every spot -on the earth’s surface is one of motion not of quiescence. -Every movement of the air, thus almost constantly perturbed, -is due directly or indirectly to the sun.</p> - -<p>So also every drop of rain or snow, every particle of -liquid or of frozen water in mist or in cloud, owes its birth -to the sun. The questions addressed of old to Job, “Hath -the rain a father? or who hath begotten the drops of dew? -out of whose womb came the ice? and the hoary frost of -heaven, who hath gendered it?” have been answered by -modern science, and to every question the answer is, The -Sun. He is parent of the snow and hail, as he is of the -moist warm rains of summer, of the ice which crowns the -everlasting hills, and of the mist which rises from the valleys -beneath his morning rays.</p> - -<p>Since, then, the snow that clothes the earth in winter as -with a garment, and the clouds that in due season drop -fatness on the earth, are alike gendered by the sun; since -every movement in our air, from the health-bringing breeze -to the most destructive hurricane, owns him as its parent; -we must at the outset admit, that if there is any body<span class="pagenum"><a id="Page_30">30</a></span> -external to the earth whose varying aspect or condition can -inform us beforehand of changes which the weather is to -undergo, the sun is that body. That for countless ages the -moon should have been regarded as the great weather-breeder, -shows only how prone men are to recognize in -apparent changes the true cause of real changes, and how -slight the evidence is on which they will base laws of association -which have no real foundation in fact. Every one can -see when the moon is full, or horned, or gibbous, or half-full; -when her horns are directed upwards, or downwards, or -sideways. And as the weather is always changing, even -as the moon is always changing, it must needs happen that -from time to time changes of weather so closely follow -changes of the moon as to suggest that the two orders of -change stand to each other in the relation of cause and -effect. Thus rough rules (such as those which Aratus has -handed down to us) came to be formed, and as (to use -Bacon’s expression) men mark when such rules hit, and -never mark when they miss, a system of weather lore -gradually comes into being, which, while in one sense based -on facts, has not in reality a particle of true evidence in its -favour—every single fact noted for each relation having -been contradicted by several unnoted facts opposed to the -relation. There could be no more instructive illustration of -men’s habits in such matters than the system of lunar -weather wisdom in vogue to this day among seamen, though -long since utterly disproved by science. But let it be remarked -in passing, that in leaving the moon, which has no -direct influence, and scarcely any indirect influence, on the -weather, for the sun, which is all-powerful, we have not got -rid of the mental habits which led men so far astray in -former times. We shall have to be specially careful lest it -lead us astray yet once more, perhaps all the more readily -because of the confidence with which we feel that, at the -outset anyway, we are on the right road.</p> - -<p>I suppose there must have been a time when men were -not altogether certain whether the varying apparent path of<span class="pagenum"><a id="Page_31">31</a></span> -the sun, as he travels from east to west every day, has any -special effect on the weather. It seems so natural to us to -recognize in the sun’s greater mid-day elevation and longer -continuance above the horizon in summer, the cause of the -greater warmth which then commonly prevails, that we find it -difficult to believe that men could ever have been in doubt -on this subject. Yet it is probable that a long time passed -after the position of the sun as ruler of the day had been -noticed, before his power as ruler of the seasons was recognized. -I cannot at this moment recall any passage in the -Bible, for example, in which direct reference is made to the -sun’s special influence in bringing about the seasons, or -any passage in very ancient writings referring definitely to -the fact that the weather changes with the changing position -of the sun in the skies (as distinguished from the star-sphere), -and with the changing length of the day. “While -the earth remaineth,” we are told in Genesis, “seed-time -and harvest, and cold and heat, and summer and winter, -and day and night, shall not cease;” but there is no reference -to the sun’s aspect as determining summer and winter. -We find no mention of any of the celestial signs of the -seasons anywhere in the Bible, I think, but such signs as -are mentioned in the parable of the fig tree—“When his -branch is yet tender, and putteth forth leaves, ye know that -summer is nigh.” Whether this indicates or not that the -terrestrial, rather than the celestial signs of the progress of -the year were chiefly noted by men in those times, it is -tolerably certain that in the beginning a long interval must -have elapsed between the recognition of the seasons themselves, -and the recognition of their origin in the changes of -the sun’s apparent motions.</p> - -<p>When this discovery was effected, men made the most -important and, I think, the most satisfactory step towards the -determination of cyclic associations between solar and terrestrial -phenomena. It is for that reason that I refer specially -to the point. In reality, it does not appertain to my subject, -for seasons and sun-spots are not associated. But it admirably<span class="pagenum"><a id="Page_32">32</a></span> -illustrates the value of cyclic relations. Men might -have gone on for centuries, we may conceive, noting the -recurrence of seed-time and harvest-time, summer and -winter, recognizing the periodical returns of heat and cold, -and (in some regions) of dry seasons and wet seasons, of -calm and storm, and so forth, without perceiving that the -sun runs through his changes of diurnal motion in the same -cyclic period. We can imagine that some few who might -notice the connection between the two orders of celestial -phenomena would be anxious to spread their faith in the -association among their less observant brethren. They -might maintain that observatories for watching the motions -of the sun would demonstrate either that their belief was -just or that it was not so, would in fact dispose finally of -the question. It is giving the most advantageous possible -position to those who now advocate the erection of solar -observatories for determining what connection, if any, may -exist between sun-spots and terrestrial phenomena, thus to -compare them to observers who had noted a relation which -unquestionably exists. But it is worthy of notice that if -those whom I have imagined thus urging the erection of an -observatory for solving the question whether the sun rules -the seasons, and to some degree regulates the recurrence -of dry or rainy, and of calm or stormy weather, had promised -results of material value from their observations, they -would have promised more than they could possibly have -performed. Even in this most favourable case, where the -sun is, beyond all question, the efficient ruling body, where -the nature of the cyclic change is most exactly determinable, -and where even the way in which the sun acts can be -exactly ascertained, no direct benefit accrues from the -knowledge. The exact determination of the sun’s apparent -motions has its value, and this value is great, but it is most -certainly not derived from any power of predicting the recurrence -of those phenomena which nevertheless depend -directly on the sun’s action. The farmer who in any -given year knows from the almanac the exact duration of<span class="pagenum"><a id="Page_33">33</a></span> -daylight, and the exact mid-day elevation of the sun for every -day in the year, is not one whit better able to protect his -crops or his herds against storm or flood than the tiller of -the soil or the tender of flocks a hundred thousand years or -so ago, who knew only when seed-time and summer and -harvest-time and winter were at hand or in progress.</p> - -<p>The evidence thus afforded is by no means promising, -then, so far as the prediction of special storms, or floods, -or droughts is concerned. It would seem that if past experience -can afford any evidence in such matters, men may -expect to recognize cycles of weather change long before -they recognize corresponding solar cycles (presuming always -that such cycles exist), and that they may expect to find -the recognition of such association utterly barren, so far as -the possibility of predicting definite weather changes is -concerned. It would seem that there is no likelihood of -anything better than what Sir J. Herschel said <em>might</em> be -hoped for hereafter. “A lucky hit may be made; nay, -some rude approach to the perception of a ‘cycle of -seasons’ may <em>possibly</em> be obtainable. But no person in his -senses would alter his plans of conduct for six months in -advance in the most trifling particular on the faith of any -special prediction of a warm or a cold, a wet or a dry, a -calm or a stormy, summer or winter”—far less of a great -storm or flood announced for any special day.</p> - -<p>But let us see what the cycle association between solar -spots and terrestrial weather actually is, or rather of what -nature it promises to be, for as yet the true nature of the -association has not been made out.</p> - -<p>It has been found that in a period of about eleven years -the sun’s surface is affected by what may be described as a -wave of sun-spots. There is a short time—a year or so—during -which scarce any spots are seen; they become more -and more numerous during the next four or five years, until -they attain a maximum of frequency and size; after this they -wane in number and dimensions, until at length, about eleven -years from the time when he had before been freest from<span class="pagenum"><a id="Page_34">34</a></span> -spots, he attains again a similar condition. After this the -spots begin to return, gradually attain to a maximum, then -gradually diminish, until after eleven more years have -elapsed few or none are seen. It must not be supposed -that the sun is always free from spots at the time of minimum -spot frequency, or that he always shows many and large -spots at the time of maximum spot frequency. Occasionally -several very large spots, and sometimes singularly large spots, -have been seen in the very heart of the minimum spot season, -and again there have been occasions when scarcely any spots -have been seen for several days in the very heart of the -maximum spot season. But, taking the average of each -year, the progression of the spots in number and frequency -from minimum to maximum, and their decline from maximum -to minimum, are quite unmistakeable.</p> - -<p>Now there are some terrestrial phenomena which we -might expect to respond in greater or less degree to the -sun’s changes of condition with respect to spots. We cannot -doubt that the emission both of light and of heat is -affected by the presence of spots. It is not altogether clear -in what way the emission is affected. We cannot at once -assume that because the spots are dark the quantity of sunlight -must be less when the spots are numerous; for it may -well be that the rest of the sun’s surface may at such times be -notably brighter than usual, and the total emission of light -may be greater on the whole instead of less. Similarly of -the emission of heat. It is certain that when there are many -spots the surface of the sun is far less uniform in brightness -than at other times. The increase of brightness all round -the spots is obvious to the eye when the sun’s image, duly -enlarged, is received upon a screen in a darkened room. -Whether the total emission of light is increased or diminished -has not yet been put to the test. Professor Langley, of the -Alleghany Observatory, near Pittsburg, U.S., has carefully -measured the diminution of the sun’s emission of light and -heat on the assumption that the portion of the surface not -marked by spots remains unchanged in lustre. But until<span class="pagenum"><a id="Page_35">35</a></span> -the total emission of light and heat at the times of maximum -and minimum has been measured, without any assumption of -the kind, we cannot decide the question.</p> - -<p>More satisfactory would seem to be the measurements -which have been made by Professor Piazzi Smyth, at -Edinburgh, and later by the Astronomer Royal at Greenwich, -into the underground temperature of the earth. By -examining the temperature deep down below the surface, all -local and temporary causes of change are eliminated, and -causes external to the earth can alone be regarded as -effective in producing systematic changes. “The effect -is very slight,” I wrote a few years ago, “indeed barely -recognizable. I have before me as I write Professor Smyth’s -sheet of the quarterly temperatures from 1837 to 1869 at -depths of 3, 6, 12, and 24 French feet. Of course the most -remarkable feature, even at the depth of 24 feet, is the -alternate rise and fall with the seasons. But it is seen that, -while the range of rise and fall remains very nearly constant, -the crests and troughs of the waves lie at varying levels.” -After describing in the essay above referred to, which appears -in my “Science Byways,” the actual configuration of the -curves of temperature both for seasons and for years, and -the chart in which the sun-spot waves and the temperature -waves are brought into comparison, I was obliged to admit -that the alleged association between the sun-spot period and -the changes of underground temperature did not seem to -me very clearly made out. It appears, however, there is a -slight increase of temperature at the time when the sun-spots -are least numerous.</p> - -<p>That the earth’s magnetism is affected by the sun’s -condition with respect to spots, seems to have been more -clearly made out, though it must be noted that the -Astronomer Royal considers the Greenwich magnetic observations -inconsistent with this theory. It seems to have -been rendered at least extremely probable that the daily -oscillation of the magnetic needle is greater when spots are -numerous than when there are few spots or none. Magnetic<span class="pagenum"><a id="Page_36">36</a></span> -storms are also more numerous at the time of maximum -spot-frequency, and auroras are then more common. (The -reader will not fall into the mistake of supposing that -magnetic storms have the remotest resemblance to hurricanes, -or rainstorms, or hailstorms, or even to thunderstorms, -though the thunderstorm is an electrical phenomenon. -What is meant by a magnetic storm is simply such a condition -of the earth’s frame that the magnetic currents traversing -it are unusually strong.)</p> - -<p>Thus far, however, we have merely considered relations -which we might fairly expect to find affected by the sun’s -condition as to spots. A slight change in his total brightness -and in the total amount of heat emitted by him may -naturally be looked for under circumstances which visibly -affect the emission of light, and presumably affect the -emission of heat also, from portions of his surface. Nor -can we wonder if terrestrial magnetism, which is directly -dependent on the sun’s emission of heat, should be affected -by the existence of spots upon his surface.</p> - -<p>It is otherwise with the effects which have recently been -associated with the sun’s condition. It may or may not -prove actually to be the case that wind and rain vary in -quantity as the sun-spots vary in number (at least when we -take in both cases the average for a year, or for two or three -years), but it cannot be said that any such relation was antecedently -to be expected. When we consider what the sun -actually does for our earth, it seems unlikely that special -effects such as these should depend on relatively minute -peculiarities of the sun’s surface. There is our earth, with -her oceans and continents, turning around swiftly on her -axis, and exposed to his rays as a whole. Or, inverting the -way of viewing matters, there is the sun riding high in the -heavens of any region of the earth, pouring down his rays -upon that region. We can understand how in the one case -that rotating orb of the earth may receive rather more or -rather less heat from the sun when he is spotted than when -he is not, or how in the other way of viewing matters, that<span class="pagenum"><a id="Page_37">37</a></span> -orb of the sun may give to any region rather more or rather -less heat according as his surface is more or less spotted. -But that in special regions of that rotating earth storms -should be more or less frequent or rainfall heavier or lighter, -as the sun’s condition changes through the exceedingly small -range of variation due to the formation of spots, seems antecedently -altogether unlikely; and equally unlikely the idea -that peculiarities affecting limited regions of the sun’s surface -should affect appreciably the general condition of the earth. -If a somewhat homely comparison may be permitted, we can -well understand how a piece of meat roasting before a fire -may receive a greater or less supply of heat on the whole as -the fire undergoes slight local changes (very slight indeed -they must be, that the illustration may be accurate); but it -would be extremely surprising if, in consequence of such -slight changes in the fire, the roasting of particular portions -of the joint were markedly accelerated or delayed, or affected -in any other special manner.</p> - -<p>But of course all such considerations as to antecedent -probabilities must give way before the actual evidence of -observed facts. Utterly inconsistent with all that is yet -known of the sun’s physical action, as it may seem, on <i xml:lang="la" lang="la">à -priori</i> grounds, to suppose that spots, currents, or other local -disturbances of the sun’s surface could produce any but -general effects on the earth as a whole, yet if we shall find that -particular effects are produced in special regions of the earth’s -surface in cycles unmistakably synchronizing with the solar-spot-cycle, -we must accept the fact, whether we can explain -it or not. Only let it be remembered at the outset that the -earth is a large place, and the variations of wind and calm, -rain and drought, are many and various in different regions. -Whatever place we select for examining the rainfall, for -example, we are likely to find, in running over the records -of the last thirty years or so, some seemingly oscillatory -changes; in the records of the winds, again, we are likely to -find other seemingly oscillatory changes; if none of these -records provide anything which seems in any way to correspond<span class="pagenum"><a id="Page_38">38</a></span> -with the solar spot-cycle, we may perchance find some -such cycle in the relative rainfall of particular months, or in -the varying wetness or dryness of particular winds, and so -forth. Or, if we utterly fail to find any such relation in one -place we may find it in another, or not improbably in half-a-dozen -places among the hundreds which are available for the -search. If we are content with imperfect correspondence -between some meteorological process or another and the -solar-spot cycle, we shall be exceedingly unfortunate indeed -if we fail to find a score of illustrative instances. And if we -only record these, without noticing any of the cases where -we fail to find any association whatever—in other words, as -Bacon puts it, if “we note when we hit and never note when -we miss,” we shall be able to make what will seem a very -strong case indeed. But this is not exactly the scientific -method in such cases. By following such a course, indeed, -we might prove almost anything. If we take, for instance, -a pack of cards, and regard the cards in order as corresponding -to the years 1825 to 1877, and note their colours as -dealt <em>once</em>, we shall find it very difficult to show that there is -any connection whatever between the colours of the cards -corresponding to particular years and the number of spots -on the sun’s face. But if we repeat the process a thousand -times, we shall find certain instances among the number, in -which red suits correspond to all the years when there are -many spots on the sun, and black suits to all the years when -there are few spots on the sun. If now we were to publish -all such deals, without mentioning anything at all about the -others which showed no such association, we should go far -to convince a certain section of the public that the condition -of the sun as to spots might hereafter be foretold by the -cards; whence, if the public were already satisfied that the -condition of the sun specially affects the weather of particular -places, it would follow that the future weather of these places -might also be foretold by the cards.</p> - -<p>I mention this matter at the outset, because many who -are anxious to find some such cycle of seasons as Sir John<span class="pagenum"><a id="Page_39">39</a></span> -Herschel thought might be discovered, have somewhat overlooked -the fact that we must not hunt down such a cycle -<i xml:lang="la" lang="la">per fas et nefas</i>. “Surely in meteorology as in astronomy,” -Mr. Lockyer writes, for instance, “the thing to hunt down -is a cycle, and if that is not to be found in the temperate -zone, then go to the frigid zones or the torrid zone to look -for it; and if found, then above all things and in whatever -manner, lay hold of, study, and read it, and see what it -means.” There can be no doubt that this is the way to find -a cycle, or at least to find what looks like a cycle, but the -worth of a cycle found in this way will be very questionable.<a id="FNanchor_7" href="#Footnote_7" class="fnanchor">7</a></p> - -<p>I would not have it understood, however, that I consider -all the cycles now to be referred to as unreal, or even that -the supposed connection between them and the solar cycle -has no existence. I only note that there are thousands, if -not tens of thousands, of relations among which cycles may -be looked for, and that there are perhaps twenty or thirty -cases in which some sort of cyclic association between certain -meteorological relations and the period of the solar spots -presents itself. According to the recognized laws of probability, -some at least amongst these cases must be regarded -as accidental. Some, however, may still remain which are -not accidental.</p> - -<p>Among the earliest published instances may be mentioned -Mr. Baxendell’s recognition of the fact that during a certain -series of years, about thirty, I think, the amount of rainfall -at Oxford was greater under west and south-west winds than -under south and south-east winds when sun-spots were most -numerous, whereas the reverse held in years when there were -no spots or few. Examining the meteorological records of<span class="pagenum"><a id="Page_40">40</a></span> -St. Petersburg, he found that a contrary state of things prevailed -there.</p> - -<p>The Rev. Mr. Main, Director of the Radcliffe Observatory -at Oxford, found that westerly winds were slightly -more common (as compared with other winds) when sun-spots -were numerous than when they were few.</p> - -<p>Mr. Meldrum, of Mauritius, has made a series of statistical -inquiries into the records of cyclones which have -traversed the Indian Ocean between the equator and 34 -degrees south latitude, in each year from 1856 to 1877, -noting the total distances traversed by each, the sums of -their radii and areas, their duration in days, the sums of -their total areas, and their relative areas. His researches, be -it marked in passing, are of extreme interest and value, -whether the suggested connection between sun-spots and -cyclones (in the region specified) be eventually found to be -a real one or not. The following are his results, as described -in <cite>Nature</cite> by a writer who manifestly favours very strongly -the doctrine that an intimate association exists between -solar maculation (or spottiness) and terrestrial meteorological -phenomena:—</p> - -<p>“The period embraces two complete, or all but complete, -sun-spot periods, the former beginning with 1856 and ending -in 1867, and the latter extending from 1867 to about the -present time [1877]. The broad result is that the number of -cyclones, the length and duration of their courses, and the -extent of the earth’s surface covered by them all, reach the -maximum in each sun-spot period during the years of -maximum maculation, and fall to the minimum during the -years of minimum maculation. The peculiar value of these -results lies in the fact that the portion of the earth’s surface -over which this investigation extends, is, from its geographical -position and what may be termed its meteorological homogeneity, -singularly well fitted to bring out prominently any -connection that may exist between the condition of the sun’s -surface and atmospheric phenomena.”</p> - -<p>The writer proceeds to describe an instance in which<span class="pagenum"><a id="Page_41">41</a></span> -Mr. Meldrum predicted future meteorological phenomena, -though without specifying the exact extent to which Mr. -Meldrum’s anticipations were fulfilled or the reverse. “A -drought commenced in Mauritius early in November,” he -says, “and Mr. Meldrum ventured (on December 21) to -express publicly his opinion that probably the drought would -not break up till towards the end of January, and that it -might last till the middle of February, adding that up to -these dates the rainfall of the island would probably not -exceed 50 per cent. of the mean fall. This opinion was an -inference grounded on past observations, which show that -former droughts have lasted from about three to three and -a half months, and that these droughts have occurred in the -years of minimum sun-spots, or, at all events, in years when -the spots were far below the average, such as 1842, 1843, -1855, 1856, 1864, 1866, and 1867, and that now we are -near the minimum epoch of sun-spots. It was further stated -that the probability of rains being brought earlier by a -cyclone was but slight, seeing that the season for cyclones -is not till February or March, and that no cyclone whatever -visited Mauritius during 1853–56 and 1864–67, the years of -minimum sun-spots. From the immense practical importance -of this application of the connection between sun-spots and -weather to the prediction of the character of the weather of -the ensuing season, we shall look forward with the liveliest -interest to a detailed statement of the weather which actually -occurred in that part of the Indian Ocean from November -to March last [1876].”</p> - -<p>It was natural that the great Indian famine, occurring at -a time when sun-spots were nearly at a minimum, should by -some be directly associated with a deficiency of sun-spots. -In this country, indeed, we have had little reason, during -the last two or three years of few sun-spots, to consider that -drought is one of the special consequences to be attributed -to deficient solar maculation. But in India it may be -different, or at least it may be different in Madras, for it has -been satisfactorily proved that in some parts of India the<span class="pagenum"><a id="Page_42">42</a></span> -rainfall increases in inverse, not in direct proportion, to -the extent of solar maculation. Dr. Hunter has shown to -the satisfaction of many that at Madras there is “a cycle -of rainfall corresponding with the period of solar maculation.” -But Mr. E. D. Archibald, who is also thoroughly -satisfied that the sun-spots affect the weather, remarks that -Dr. Hunter has been somewhat hasty in arguing that the -same conditions apply throughout the whole of Southern -India. “This hasty generalization from the results of one -station situated in a vast continent, the rainfall of which -varies completely, both in amount and the season in which -it falls, according to locality, has been strongly contested -by Mr. Blanford, the Government Meteorologist, who, in -making a careful comparison of the rainfalls of seven -stations, three of which (Madras, Bangalore, and Mysore) -are in Southern India, the others being Bombay, Najpore, -Jubbulpore, and Calcutta, finds that, with the exception of -Najpore in Central India, which shows some slight approach -to the same cyclical variation which is so distinctly marked -in the Madras registers, the rest of the stations form complete -exceptions to the rule adduced for Madras, in many -of them the hypothetical order of relation being reversed. -Mr. Blanford, however, shows that, underlying the above -irregularities, a certain cyclical variation exists on the -average at all the stations, the amount, nevertheless, being -so insignificant (not more than 9 per cent. of the total falls) -that it could not be considered of sufficient magnitude to -become a direct factor in the production of famine. It thus -appears that the cycle of rainfall which is considered to be -the most important element in causing periodic famines has -only been proved satisfactorily for the town of Madras. It -may perhaps hold for the Carnatic and Northern Siccars, -the country immediately surrounding Madras, though perhaps, -owing to the want of rainfall registers in these districts, -evidence with regard to this part is still wanting.” -On this Mr. Archibald proceeds to remark that, though Dr. -Hunter has been only partially successful, the value of his<span class="pagenum"><a id="Page_43">43</a></span> -able pamphlet is not diminished in any way, “an indirect -effect of which has been to stimulate meteorological inquiry -and research in the same direction throughout India. The -meteorology of this country (India), from its peculiar and -tropical position, is in such complete unison with any -changes that may arise from oscillations in the amount of -solar radiation, and their effects upon the velocity and direction -of the vapour-bearing winds, that a careful study of -it cannot fail to discover meteorological periodicities in close -connection with corresponding periods of solar disturbance.” -So, indeed, it would seem.</p> - -<p>The hope that famines may be abated, or, at least, some -of their most grievous consequences forestalled by means of -solar observatories, does not appear very clearly made out. -Rather it would seem that the proper thing to do is to -investigate the meteorological records of different Indian -regions, and consider the resulting evidence of cyclic -changes without any special reference to sun-spots; for if -sun-spots may cause drought in one place, heavy rainfall in -another, winds here and calms there, it seems conceivable -that the effects of sun-spots may differ at different times, as -they manifestly do in different places.</p> - -<p>Let us turn, however, from famines to shipwrecks. Perhaps, -if we admit that cyclones are more numerous, and -blow more fiercely, and range more widely, even though it -be over one large oceanic region only, in the sun-spot -seasons than at other times, we may be assured, without -further research, that shipwrecks will, on the whole, be more -numerous near the time of sun-spot maxima than near the -time of sun-spot minima.</p> - -<p>The idea that this may be so was vaguely shadowed -forth in a poem of many stanzas, called “The Meteorology -of the Future: a Vision,” which appeared in <cite>Nature</cite> for -July 5, 1877. I do not profess to understand precisely -what the object of this poem may have been—I mean, -whether it is intended to support or not the theory that -sun-spots influence the weather. Several stanzas are very<span class="pagenum"><a id="Page_44">44</a></span> -humorous, but the object of the humour is not manifest. -The part referred to above is as follows:—Poor Jack lies -at the bottom of the sea in 1881, and is asked in a spiritual -way various questions as to the cause of his thus coming -to grief. This he attributed to the rottenness of the ship -in which he sailed, to the jobbery of the inspector, to the -failure of the system of weather telegraphing, and so forth. -But, says the questioner, there was one</p> - -<div class="poem-container"> -<div class="poem"><div class="stanza"> -<span class="iq">“In fame to none will yield,<br /></span> -<span class="i0">He led the band who reaped renown<br /></span> -<span class="i0">On India’s famine field.<br /></span> -</div><div class="stanza"> -<span class="iq">“Was he the man to see thee die?<br /></span> -<span class="i0">Thou wilt not tax him—come?<br /></span> -<span class="i0">The dead man groaned—‘<em>I met my death</em><br /></span> -<span class="i0"><em>Through a sun-spot maximum</em>.’”<br /></span> -</div></div> -</div> - -<p>The first definite enunciation, however, of a relation -between sun-spots and shipwrecks appeared in September, -1876. Mr. Henry Jeula, in the <cite>Times</cite> for September 19, -stated that Dr. Hunter’s researches into the Madras rainfall -had led him to throw together the scanty materials available -relating to losses posted on Lloyd’s loss book, to ascertain -if any coincidences existed between the varying number of -such losses and Dr. Hunter’s results. “For,” he proceeds, -“since the cycle of rainfall at Madras coincides, I am -informed, with the periodicity of the cyclones in the adjoining -Bay of Bengal” (a relation which is more than doubtful) -“as worked out by the Government Astronomer at Mauritius” -(whose researches, however, as we have seen, related -to a region remote from the Bay of Bengal), “some coincidence -between maritime casualties, rainfalls, and sun-spots -appeared at least possible.” In passing, I may note that -if any such relation were established, it would be only an -extension of the significance of the cycle of cyclones, and -could have no independent value. It would certainly follow, -if the cycle of cyclones is made out, that shipwrecks being -more numerous, merchants would suffer, and we should<span class="pagenum"><a id="Page_45">45</a></span> -have the influence of the solar spots asserting itself in the -<cite>Gazette</cite>. From the cyclic derangement of monetary and -mercantile matters, again, other relations also cyclic in -character would arise. But as all these may be inferred -from the cycle of cyclones once this is established, we could -scarcely find in their occurrence fresh evidence of the necessity -of that much begged-for solar observatory. The last -great monetary panic in this country, by the way, occurred -in 1866, at a time of minimum solar maculation. Have we -here a decisive proof that the sun rules the money market, -the bank rate of discount rising to a maximum as the sun-spots -sink to a minimum, and <i xml:lang="la" lang="la">vice versâ</i>? The idea is -strengthened by the fact that the American panic in 1873 -occurred when spots were very numerous, and its effects -have steadily subsided as the spots have diminished in -number; for this shows that the sun rules the money market -in America on a principle diametrically opposed to that on -which he (manifestly) rules the money market in England, -precisely as the spots cause drought in Calcutta and -plenteous rainfall at Madras, wet south-westers and dry -south-westers at Oxford, and wet south-easters and dry -south-easters at St. Petersburg. Surely it would be unreasonable -to refuse to recognize the weight of evidence which -thus tells on both sides at once.</p> - -<p>To return, however, to the sun’s influence upon shipwrecks.</p> - -<p>Mr. Jeula was “only able to obtain data for two complete -cycles of eleven years, namely, from 1855 to 1876 -inclusive, while the period investigated by Dr. Hunter extended -from 1813 to 1876, and his observations related to -Madras and its neighbourhood only, while the losses posted -at Lloyd’s occurred to vessels of various countries, and -happened in different parts of the world. It was necessary -to bring these losses to some common basis of comparison, -and the only available one was the number of ‘British -registered vessels of the United Kingdom and Channel -Islands’—manifestly an arbitrary one. I consequently cast<span class="pagenum"><a id="Page_46">46</a></span> -out the percentage of losses posted each year upon the -number of registered vessels for the same year, and also -the percentage of losses posted in each of the eleven years -of the two cycles upon the total posted in each complete -cycle, thus obtaining two bases of comparison independent -of each other.”</p> - -<p>The results may be thus presented:—</p> - -<p>Taking the four years of each cycle when sun-spots were -least in number, Mr. Jeula found the mean percentage of -losses in registered vessels of the United Kingdom and -Channel Islands to be 11·13, and the mean percentage of -losses in the total posted in the entire cycle of eleven years -to be 8·64.</p> - -<p>In the four years when sun-spots were intermediate in -number, that is in two years following the minimum and in -two years preceding the minimum, the respective percentages -were 11·91 and 9·21.</p> - -<p>Lastly, in the three years when sun-spots were most -numerous, these percentages were, respectively, 12·49 and -9·53.</p> - -<p>That the reader may more clearly understand what is -meant here by percentages, I explain that while the numbers -11·13, 11·91 and 12·49 simply indicate the average number -of wrecks (per hundred of all the ships registered) which -occurred in the several years of the eleven-years cycle, the -other numbers, 8·64, 19·21, and 9·53, indicate the average -number of wrecks (per hundred of wrecks recorded) during -eleven successive years, which occurred in the several years -of the cycle. The latter numbers seem more directly to the -purpose; and as the two sets agree pretty closely, we may -limit our attention to them.</p> - -<p>Now I would in the first place point out that it would -have been well if the actual number or percentage had been -indicated for each year of the cycle, instead of for periods of -four years, four years, and three years. Two eleven-year -cycles give in any case but meagre evidence, and it would -have been well if the evidence had been given as fully as<span class="pagenum"><a id="Page_47">47</a></span> -possible. If we had a hundred eleven-yearly cycles, and -took the averages of wrecks for the four years of minimum -solar maculation, the four intermediate years, and the three -years of maximum maculation, we might rely with considerable -confidence on the result, because accidental peculiarities -one way or the other could be eliminated. But in two -cycles only, such peculiarities may entirely mask any cyclic -relation really existing, and appear to indicate a relation -which has no real existence. If the percentages had been -given for each year, the effect of such peculiarities would -doubtless still remain, and the final result would not be more -trustworthy than before; but we should have a chance of -deciding whether such peculiarities really exist or not, -and also of determining what their nature may be. As an -instance in point, let me cite a case where, having only the -results of a single cycle, we can so arrange them as to appear -to indicate a cyclic association between sun-spots and rainfall, -while, when we give them year by year, such an association -is discredited, to say the least.</p> - -<p>The total rainfall at Port Louis, between the years 1855 -and 1868 inclusive, is as follows:—</p> - -<table class="p1" summary="Rainfall at Port Louis in 1855" style="max-width: 25em; margin: auto;"> - <tr> - <td class="tdc rpad">In</td> - <td class="tdc" colspan="2"><i>Rainfall.</i></td> - <td class="tdc"><i>Condition of Sun.</i></td></tr> - <tr> - <td class="tdc rpad">1855</td> - <td class="tdc">42·665</td> - <td class="tdc">inches</td> - <td class="tdl lpad">Sun-spot minimum.</td></tr> - <tr> - <td class="tdc rpad">1856</td> - <td class="tdc">46·230</td> - <td class="tdc">„</td></tr> - <tr> - <td class="tdc rpad">1857</td> - <td class="tdc">43·445</td> - <td class="tdc">„</td></tr> - <tr> - <td class="tdc rpad">1858</td> - <td class="tdc">35·506</td> - <td class="tdc">„</td></tr> - <tr> - <td class="tdc rpad">1859</td> - <td class="tdc">56·875</td> - <td class="tdc">„</td></tr> - <tr> - <td class="tdc rpad">1860</td> - <td class="tdc">45·166</td> - <td class="tdc">„</td> - <td class="tdl lpad">Sun-spot maximum.</td></tr> - <tr> - <td class="tdc rpad">1861</td> - <td class="tdc">68·733</td> - <td class="tdc">„</td></tr> - <tr> - <td class="tdc rpad">1862</td> - <td class="tdc">28·397</td> - <td class="tdc">„</td></tr> - <tr> - <td class="tdc rpad">1863</td> - <td class="tdc">33·420</td> - <td class="tdc">„</td></tr> - <tr> - <td class="tdc rpad">1864</td> - <td class="tdc">24·147</td> - <td class="tdc">„</td></tr> - <tr> - <td class="tdc rpad">1865</td> - <td class="tdc">44·730</td> - <td class="tdc">„</td></tr> - <tr> - <td class="tdc rpad">1866</td> - <td class="tdc">20·571</td> - <td class="tdc">„</td> - <td class="tdl lpad">Sun-spot minimum.</td></tr> - <tr> - <td class="tdc rpad">1867</td> - <td class="tdc">35·970</td> - <td class="tdc">„</td></tr> - <tr> - <td class="tdc rpad">1868</td> - <td class="tdc">64·180</td> - <td class="tdc">„</td></tr> -</table> - -<div id="ip_47" class="figcenter" style="max-width: 31.5em;"> - <img src="images/i_048.jpg" width="504" height="365" alt="" /></div> - -<p>I think no one, looking at these numbers as they stand, -can recognize any evidence of a cyclic tendency. If we -represent the rainfall by ordinates we get the accompanying<span class="pagenum"><a id="Page_48">48</a></span> -figure, which shows the rainfall for eighteen years, and again -I think it may be said that a very lively imagination is -required to recognize anything resembling that wave-like -undulation which the fundamental law of statistics requires -where a cycle is to be made out from a single oscillation. -Certainly the agreement between the broken curve of rainfall -and the sun-spot curve indicated by the waved dotted line is -not glaringly obvious. But when we strike an average for -the rainfall, in the way adopted by Mr. Jeula for shipwrecks, -how pleasantly is the theory of sun-spot influence illustrated -by the Port Louis rainfall! Here is the result, as quoted by -the high-priest of the new order of diviners, from the papers -by Mr. Meldrum:—</p> - -<table summary="Rainfall" style="max-width: 25em; margin: auto;"> - <tr> - <td class="tdl">Three minimum years—total rainfall</td> - <td class="tdl">133·340</td></tr> - <tr> - <td class="tdl">Three maximum years—total rainfall</td> - <td class="tdl">170·774</td></tr> - <tr> - <td class="tdl">Three minimum years—total rainfall</td> - <td class="tdl">120·721</td></tr> -</table> - -<p>Nothing could be more satisfactory, but nothing, I venture to -assert, more thoroughly inconsistent with the true method of -statistical research.</p> - -<p><span class="pagenum"><a id="Page_49">49</a></span> -May it not be that, underlying the broad results presented -by Mr. Jeula, there are similar irregularities?</p> - -<p>When we consider that the loss of ships depends, not only -on a cause so irregularly variable (to all seeming) as wind-storms, -but also on other matters liable to constant change, -as the variations in the state of trade, the occurrence of wars -and rumours of wars, special events, such as international -exhibitions, and so forth, we perceive that an even wider -range of survey is required to remove the effects of accidental -peculiarities in their case, than in the case of rainfall, -cyclones, or the like. I cannot but think, for instance, that -the total number of ships lost in divers ways during the -American war, and especially in its earlier years (corresponding -with two of the three maximum years of sun-spots) may -have been greater, not merely absolutely but relatively, than -in other years. I think it conceivable, again, that during -the depression following the great commercial panic of 1866 -(occurring at a time of minimum solar maculation, as already -noticed) the loss of ships may have been to some degree -reduced, relatively as well as absolutely. We know that -when trade is unusually active many ships have sailed, and -perhaps may still be allowed to sail (despite Mr. Plimsoll’s -endeavours), which should have been broken up; whereas -in times of trade depression the ships actually afloat are -likely to be, <em>on the average</em>, of a better class. So also, when, -for some special reason, passenger traffic at sea is abnormally -increased. I merely mention these as illustrative cases of -causes not (probably) dependent on sun-spots, which may -(not improbably) have affected the results examined by Mr. -Jeula. I think it possible that those results, if presented for -each year, would have indicated the operation of such -causes, naturally masked when sets of four years, four years, -and three years are taken instead of single years.</p> - -<p>I imagine that considerations such as these will have to -be taken into account and disposed of before it will be -unhesitatingly admitted that sun-spots have any great effect -in increasing the number of shipwrecks.</p> - -<p><span class="pagenum"><a id="Page_50">50</a></span> -The advocates of the doctrine of sun-spot influence—or, -perhaps it would be more correct to say, the advocates of -the endowment of sun-spot research—think differently on -these and other points. Each one of the somewhat doubtful -relations discussed above is constantly referred to by them -as a demonstrated fact, and a demonstrative proof of the -theory they advocate. For instance, Mr. Lockyer, in referring -to Meldrum’s statistical researches into the frequency of -cyclones, does not hesitate to assert that according to these -researches “the whole question of cyclones is merely a -question of solar activity, and that if we wrote down in one -column the number of cyclones in any given year, and in -another column the number of sun-spots in any given year, -there will be a strict relation between them—many sun-spots, -many hurricanes; few sun-spots, few hurricanes.” ... And -again, “Mr. Meldrum has since found” (not merely “has -since found reason to believe,” but definitely, “has since -found”) “that what is true of the storms which devastate the -Indian Ocean is true of the storms which devastate the West -Indies; and on referring to the storms of the Indian Ocean, -Mr. Meldrum points out that at those years where we have -been quietly mapping the sun-spot maxima, the harbours -were filled with wrecks, and vessels coming in disabled -from every part of the Indian Ocean.” Again, Mr. Balfour -Stewart accepts Mr. Jeula’s statistics confidently as demonstrating -that there are most shipwrecks during periods of -maximum solar activity. Nor are the advocates of the new -method of prediction at all doubtful as to the value of these -relations in affording the basis of a system of prediction. -They do not tell us precisely <em>how</em> we are to profit by the -fact, if fact it is, that cyclones and shipwrecks mark the time -of maximum solar maculation, and droughts and famine the -time of minimum. “If we can manage to get at these -things,” says Mr. Lockyer, “the power of prediction, that -power which would be the most useful one in meteorology, if -we could only get at it, would be within our grasp.” And Mr. -Balfour Stewart, in a letter to the <cite>Times</cite>, says, “If we are on<span class="pagenum"><a id="Page_51">51</a></span> -the track of a discovery which will in time enable us to foretell -the cycle of droughts, public opinion should demand -that the investigation be prosecuted with redoubled vigour -and under better conditions. If forewarned be forearmed, -then such research will ultimately conduce to the saving of -life both at times of maximum and minimum sun-spot -frequency.”</p> - -<p>If these hopes are really justified by the facts of the -case, it would be well that the matter should be as quickly -as possible put to the test. No one would be so heartless, -I think, as to reject, through an excess of scientific caution, -a scheme which might issue in the saving of many lives from -famine or from shipwreck. And on the other hand, no one, -I think, would believe so ill of his fellow-men as to suppose -for one moment that advantage could be taken of the sympathies -which have been aroused by the Indian famine, or -which may from time to time be excited by the record of -great disasters by sea and land, to advocate bottomless -schemes merely for purposes of personal advancement. We -must now, perforce, believe that those who advocate the -erection of new observatories and laboratories for studying -the physics of the sun, have the most thorough faith in the -scheme which they proffer to save our Indian population -from famine and our seamen from shipwreck.</p> - -<p>But they, on the other hand, should now also believe that -those who have described the scheme as entirely hopeless, do -really so regard it. If we exonerate them from the charge of -responding to an appeal for food by offering spectroscopes, -they in turn should exonerate us from the charge of denying -spectroscopes to the starving millions of India though -knowing well that the spectroscopic track leads straight to -safety.</p> - -<p>I must acknowledge I cannot for my own part see even -that small modicum of hope in the course suggested which -would suffice to justify its being followed. In my opinion, -one ounce of rice would be worth more (simply because it -would be worth something) than ten thousand tons of spectroscopes.<span class="pagenum"><a id="Page_52">52</a></span> -For what, in the first place, has been shown as to -the connection between meteorological phenomena and sun-spots? -Supposing we grant, and it is granting a great deal, -that all the cycles referred to have been made out. They -one and all affect averages only. The most marked among -them can so little be trusted in detail that while the maximum -of sun-spots agrees <em>in the main</em> with an excess or defect of -rain or wind, or of special rains with special winds, or the like, -the actual year of maximum may present the exact reverse.</p> - -<p>Of what use can it be to know, for instance, that the three -years of least solar maculation will probably give a rainfall -less than that for the preceding or following three years, if the -middle year of the three, when the spots are most numerous -of all, <em>may</em> haply show plenteous rainfall? Or it may be -the first of the three, or the last, which is thus well supplied, -while a defect in the other two, or in one of the others, -brings the total triennial rainfall below the average. What -provision could possibly be made under such circumstances -to meet a contingency which may occur in any one of three -years? or, at least, what provision could be made which would -prove nearly so effective as an arrangement which could -readily be made for keeping sufficient Government stores at -suitable stations (that is, never allowing such stores to fall at -the critical season in each year below a certain minimum), -and sending early telegraphic information of unfavourable -weather? Does any one suppose that the solar rice-grains are -better worth watching for such a purpose than the terrestrial -rice-grains, or that it is not well within the resources of -modern science and modern means of communication and -transport, to make sufficient preparation each year for a -calamity always possible in India? And be it noticed that -if, on the one hand, believers in solar safety from famine may -urge that, in thus objecting to their scheme, I am opposing -what might, in some year of great famine and small sun-spots, -save the lives of a greater number than would be saved by -any system of terrestrial watchfulness, I would point out, on -the other, that the solar scheme, if it means anything at all,<span class="pagenum"><a id="Page_53">53</a></span> -means special watchfulness at the minimum sun-spot season, -and general confidence (so far as famine is concerned) at the -season of maximum solar maculation; and that while as yet -nothing has been really proved about the connection between -sun-spots and famine, such confidence might prove to be a -very dangerous mistake.</p> - -<p>Supposing even it were not only proved that sun-spots -exert such and such effects, but that this knowledge can avail -to help us to measures of special precaution, how is the study -of the sun going to advance our knowledge? In passing, let -it be remarked that already an enormous number of workers -are engaged in studying the sun in every part of the world. -The sun is watched on every fine day, in every quarter of -the earth, with the telescope, analyzed with the spectroscope, -his prominences counted and measured, his surface photographed, -and so forth. What more ought to be or could be -done? But that is not the main point. If more could be -done, what could be added to our knowledge which would -avail in the way of prediction? “At present,” says Mr. -Balfour Stewart, “the problem has not been pursued on a -sufficiently large scale or in a sufficient number of places. If -the attack is to be continued, the skirmishers should give -way to heavy guns, and these should be brought to bear -without delay now that the point of attack is known.” In -other words, now that we know, according to the advocates -of these views, that meteorological phenomena follow roughly -the great solar-spot period, we should prosecute the attack -in this direction, in order to find out—what? Minor -periods, perhaps, with which meteorological phenomena may -still more roughly synchronize. Other such periods are -already known with which meteorological phenomena have -never yet been associated. New details of the sun’s surface? -No one has yet pretended that any of the details already -known, except the spots, affect terrestrial weather, and the -idea that peculiarities so minute as hitherto to have escaped -detection can do so, is as absurd, on the face of it, as the -supposition that minute details in the structure of a burning<span class="pagenum"><a id="Page_54">54</a></span> -coal, such details as could only be detected by close scrutiny, -can affect the general quality and effects of the heat transmitted -by the coal, as part of a large fire, to the further side -of a large room.</p> - -<p>Lastly, I would urge this general argument against a -theory which seems to me to have even less to recommend -it to acceptance than the faith in astrology.<a id="FNanchor_8" href="#Footnote_8" class="fnanchor">8</a> <em>If it requires,<span class="pagenum"><a id="Page_55">55</a></span> -as we are so strongly assured, the most costly observations, the -employment of the heaviest guns (and “great guns” are generally -expensive), twenty or thirty years of time, and the closest -scrutiny and research, to prove that sun-spots affect terrestrial -relations in a definite manner, effects so extremely difficult to -demonstrate cannot possibly be important enough to be worth -predicting.</em></p> - -<hr /> - -<p><span class="pagenum"><a id="Page_56">56</a></span></p> - -<div class="chapter"> -<h2><a id="NEW_WAYS_OF_MEASURING_THE_SUNS_DISTANCE"></a><i>NEW WAYS OF MEASURING THE SUN’S DISTANCE.</i></h2> -</div> - -<p class="in0">It is strange that the problem of determining the sun’s distance, -which for many ages was regarded as altogether -insoluble, and which even during later years had seemed -fairly solvable in but one or two ways, should be found, -on closer investigation, to admit of many methods of solution. -If astronomers should only be as fortunate hereafter -in dealing with the problem of determining the distances of -the stars, as they have been with the question of the sun’s -distance, we may hope for knowledge respecting the structure -of the universe such as even the Herschels despaired of our -ever gaining. Yet this problem of determining star-distances -does not seem more intractable, now, than the problem of -measuring the sun’s distance appeared only two centuries -ago. If we rightly view the many methods devised for dealing -with the easier task, we must admit that the more difficult—which, -by the way, is in reality infinitely the more interesting—cannot -be regarded as so utterly hopeless as, with -our present methods and appliances, it appears to be. True, -we know only the distances of two or three stars, approximately, -and have means of forming a vague opinion about the -distances of only a dozen others, or thereabouts, while at -distances now immeasurable lie six thousand stars visible to -the eye, and twenty millions within range of the telescope. -Yet, in Galileo’s time, men might have argued similarly -against all hope of measuring the proportions of the solar<span class="pagenum"><a id="Page_57">57</a></span> -system. “We know only,” they might have urged, “the -distance of the moon, our immediate neighbour,—beyond -her, at distances so great that hers, so far as we can judge, -is by comparison almost as nothing, lie the Sun and Mercury, -Venus and Mars; further away yet lie Jupiter and -Saturn, and possibly other planets, not visible to the naked -eye, but within range of that wonderful instrument, the -telescope, which our Galileo and others are using so successfully. -What hope can there be, when the exact measurement -of the moon’s distance has so fully taxed our powers of -celestial measurement, that we can ever obtain exact information -respecting the distances of the sun and planets? By -what method is a problem so stupendous to be attacked?” -Yet, within a few years of that time, Kepler had formed -already a rough estimate of the distance of the sun; in 1639, -young Horrocks pointed to a method which has since been -successfully applied. Before the end of the seventeenth -century Cassini and Flamsteed had approached the solution -of the problem more nearly, while Hailey had definitely formulated -the method which bears his name. Long before -the end of the eighteenth century it was certainly known -that the sun’s distance lies between 85 millions of miles and -98 millions (Kepler, Cassini, and Flamsteed had been unable -to indicate any superior limit). And lastly, in our own time, -half a score of methods, each subdivisible into several forms, -have been applied to the solution of this fundamental problem -of observational astronomy.</p> - -<p>I propose now to sketch some new and very promising -methods, which have been applied already with a degree of -success arguing well for the prospects of future applications -of the methods under more favourable conditions.</p> - -<p>In the first place, let us very briefly consider the methods -which had been before employed, in order that the proper -position of the new methods may be more clearly recognized.</p> - -<p>The plan obviously suggested at the outset for the solution -of the problem was simply to deal with it as a problem -of surveying. It was in such a manner that the moon’s<span class="pagenum"><a id="Page_58">58</a></span> -distance had been found, and the only difficulty in applying -the method to the sun or to any planet consisted in the -delicacy of the observations required. The earth being the -only surveying-ground available to astronomers in dealing -with this problem (in dealing with the problem of the stars’ -distances they have a very much wider field of operations), -it was necessary that a base-line should be measured on this -globe of ours,—large enough compared with our small selves, -but utterly insignificant compared with the dimensions of the -solar system. The diameter of the earth being less than -8000 miles, the longest line which the observers could take -for base scarcely exceeded 6000 miles; since observations -of the same celestial object at opposite ends of a diameter -necessarily imply that the object is in the horizon of <em>both</em> the -observing stations (for precisely the same reason that two -cords stretched from the ends of any diameter of a ball to a -distant point touch the ball at those ends). But the sun’s -distance being some 92 millions of miles, a base of 6000 -miles amounts to less than the 15,000th part of the distance -to be measured. Conceive a surveyor endeavouring to determine -the distance of a steeple or rock 15,000 feet, or nearly -three miles, from him, with a base-line <em>one foot</em> in length, -and you can conceive the task of astronomers who should -attempt to apply the direct surveying method to determine -the sun’s distance,—at least, you have one of their difficulties -strikingly illustrated, though a number of others remain -which the illustration does not indicate. For, after all, a -base one foot in length, though far too short, is a convenient -one in many respects: the observer can pass from one end -to the other without trouble—he looks at the distant object -under almost exactly the same conditions from each end, -and so forth. A base 6000 miles long for determining the -sun’s distance is too short in precisely the same degree, but -it is assuredly not so convenient a base for the observer. A -giant 36,000 miles high would find it as convenient as a surveyor -six feet high would find a one foot base-line; but -astronomers, as a rule, are less than 36,000 miles in height.<span class="pagenum"><a id="Page_59">59</a></span> -Accordingly the same observer cannot work at both ends of -the base-line, and they have to send out expeditions to -occupy each station. All the circumstances of temperature, -atmosphere, personal observing qualities, etc., are unlike at -the two ends of the base-line. The task of measuring the -sun’s distance directly is, in fact, at present beyond the -power of observational astronomy, wonderfully though its -methods have developed in accuracy.</p> - -<p>We all know how, by observations of Venus in transit, -the difficulty has been so far reduced that trustworthy results -have been obtained. Such observations belong to the -surveying method, only Venus’s distance is made the object -of measurement instead of the sun’s. The sun serves simply -as a sort of dial-plate, Venus’s position while in transit across -this celestial dial-plate being more easily measured than -when she is at large upon the sky. The devices by which -Halley and Delisle severally caused <em>time</em> to be the relation -observed, instead of position, do not affect the general -principle of the transit method. It remains dependent on -the determination of position. Precisely as by the change -of the <em>position</em> of the hands of a clock on the face we measure -<em>time</em>, so by the transit method, as Halley and Delisle respectively -suggested its use, we determine Venus’s position on -the sun’s face, by observing the difference of the time she -takes in crossing, or the difference of the time at which she -begins to cross, or passes off, his face.</p> - -<p>Besides the advantage of having a dial-face like the sun’s -on which thus to determine positions, the transit method -deals with Venus when at her nearest, or about 25 million -miles from us, instead of the sun at his greater distance of -from 90½ to 93½ millions of miles. Yet we do not get the -entire advantage of this relative proximity of Venus. For -the dial-face—the sun, that is—changes its position too—in -less degree than Venus changes hers, but still so much as -largely to reduce her seeming displacement. The sun being -further away as 92 to 25, is less displaced as 25 to 92. -Venus’s displacement is thus diminished by 25/92nds of its full<span class="pagenum"><a id="Page_60">60</a></span> -amount, leaving only 67/92nds. Practically, then, the advantage -of observing Venus, so far as distance is concerned, is the -same as though, instead of being at a distance of only 25 -million miles, her distance were greater as 92 to 67, giving -as her effective distance when in transit some 34,300,000 -miles.</p> - -<p>All the methods of observing Venus in transit are affected -in <em>this</em> respect. Astronomers were not content during the -recent transit to use Halley’s and Delisle’s two time methods -(which may be conveniently called the duration method and -the epoch method), but endeavoured to determine the -position of Venus on the sun’s face directly, both by observation -and by photography. The heliometer was the instrument -specially used for the former purpose; and as, in one -of the new methods to be presently described, this is the -most effective of all available instruments, a few words as to -its construction will not be out of place.</p> - -<p>The heliometer, then, is a telescope whose object-glass -(that is, the large glass at the end towards the object -observed) is divided into two halves along a diameter. -When these two halves are exactly together—that is, in the -position they had before the glass was divided—of course -they show any object to which they may be directed precisely -as they would have done before the glass was cut. But if, -without separating the straight edges of the two semicircular -glasses, one be made to slide along the other, the images -formed by the two no longer coincide.<a id="FNanchor_9" href="#Footnote_9" class="fnanchor">9</a> Thus, if we are -looking at the sun we see two overlapping discs, and by -continuing to turn the screw or other mechanism which -carries our half-circular glass past the other, the disc-images<span class="pagenum"><a id="Page_61">61</a></span> -of the sun may be brought entirely clear of each other. -Then we have two suns in the same field of view, seemingly -in contact, or nearly so. Now, if we have some means of -determining how far the movable half-glass has been carried -past the other to bring the two discs into apparently exact -contact, we have, in point of fact, a measure of the sun’s -apparent diameter. We can improve this estimate by carrying -back the movable glass till the images coincide again, -then further back till they separate the other way and finally -are brought into contact on that side. The entire range, -from contact on one side to contact on the other side, gives -twice the entire angular span of the sun’s diameter; and the -half of this is more likely to be the true measure of the -diameter, than the range from coincident images to contact -either way, simply because instrumental errors are likely to -be more evenly distributed over the double motion than over -the movement on either side of the central position. The -heliometer derived its name—which signifies sun-measurer—from -this particular application of the instrument.</p> - -<p>It is easily seen how the heliometer was made available -in determining the position of Venus at any instant during -transit. The observer could note what displacement of the -two half-glasses was necessary to bring the black disc of -Venus on one image of the sun to the edge of the other -image, first touching on the inside and then on the outside. -Then, reversing the motion, he could carry her disc to the -opposite edge of the other image of the sun, first touching -on the inside and then on the outside. Lord Lindsay’s -private expedition—one of the most munificent and also one -of the most laborious contributions to astronomy ever made—was -the only English expedition which employed the -heliometer, none of our public observatories possessing such -an instrument, and official astronomers being unwilling to ask -Government to provide instruments so costly. The Germans, -however, and the Russians employed the heliometer very -effectively.</p> - -<p>Next in order of proximity, for the employment of the<span class="pagenum"><a id="Page_62">62</a></span> -direct surveying method, is the planet Mars when he comes -into opposition (or on the same line as the earth and sun) in -the order</p> - -<p class="center"> -Sun____________________________Earth__________Mars, -</p> - -<p class="in0 p1">at a favourable part of his considerably eccentric orbit. His -distance then may be as small as 34½ millions of miles; and -we have in his case to make no reduction for the displacement -of the background on which his place is to be determined. -That background is the star sphere, his place being -measured from that of stars near which his apparent path on -the heavens carries him; and the stars are so remote that the -displacement due to a distance of six or seven thousand -miles between two observers on the earth is to all intents -and purposes nothing. The entire span of the earth’s orbit -round the sun, though amounting to 184 millions of miles, -is a mere point as seen from all save ten or twelve stars; -how utterly evanescent, then, the span of the earth’s globe—less -than the 23,000th part of her orbital range! Thus the -entire displacement of Mars due to the distance separating -the terrestrial observers comes into effect. So that, in comparing -the observation of Mars in a favourable opposition -with that of Venus in transit, we may fairly say that, so far -as surveying considerations are concerned, the two planets -are equally well suited for the astronomer’s purpose. -Venus’s less distance of 25 millions of miles is effectively -increased to 34⅓ millions by the displacement of the solar -background on which we see her when in transit; while -Mars’s distance of about 34½ millions of miles remains -effectively the same when we measure his displacement from -neighbouring fixed stars.</p> - -<p>But in many respects Mars is superior to Venus for the -purpose of determining the sun’s distance. Venus can only -be observed at her nearest when in transit, and transit lasts -but a few hours. Mars can be observed night after night -for a fortnight or so, during which his distance still remains -near enough to the least or opposition distance. Again,<span class="pagenum"><a id="Page_63">63</a></span> -Venus being observed on the sun, all the disturbing influences -due to the sun’s heat are at work in rendering the -observation difficult. The air between us and the sun at -such a time is disturbed by undulations due in no small -degree to the sun’s action. It is true that we have not, in -the case of Mars, any means of substituting time measures -or time determinations for measures of position, as we have -in Venus’s case, both with Halley’s and Delisle’s methods. -But to say the truth, the advantage of substituting these time -observations has not proved so great as was expected. -Venus’s unfortunate deformity of figure when crossing the -sun’s edge renders the determination of the exact moments of -her entry on the sun’s face and of her departure from it by no -means so trustworthy as astronomers could wish. On the -whole, Mars would probably have the advantage even without -that point in his favour which has now to be indicated.</p> - -<p>Two methods of observing Mars for determining the -sun’s distance are available, both of which, as they can be -employed in applying one of the new methods, may -conveniently be described at this point.</p> - -<p>An observer far to the north of the earth’s equator sees -Mars at midnight, when the planet is in opposition, displaced -somewhat to the south of his true position—that is, of the -position he would have as supposed to be seen from the -centre of the earth. On the other hand, an observer far to -the south of the equator sees Mars displaced somewhat to -the north of his true position. The difference may be compared -to different views of a distant steeple (projected, let -us suppose, against a much more remote hill), from the -uppermost and lowermost windows of a house corresponding -to the northerly and southerly stations on the earth, and -from a window on the middle story corresponding to a view -of Mars from the earth’s centre. By ascertaining the displacement -of the two views of Mars obtained from a station -far to the north and another station far to the south, the -astronomer can infer the distance of the planet, and thence -the dimensions of the solar system. The displacement is<span class="pagenum"><a id="Page_64">64</a></span> -determinable by noticing Mars’s position with respect to -stars which chance to be close to him. For this purpose the -heliometer is specially suitable, because, having first a view -of Mars and some companion stars as they actually are -placed, the observer can, by suitably displacing the movable -half-glass, bring the star into apparent contact with the -planet, first on one side of its disc, and then on the other -side—the mean of the two resulting measures giving, of -course, the distance between the star and the centre of the -disc.</p> - -<p>This method requires that there shall be two observers, -one at a northern station, as Greenwich, or Paris, or Washington, -the other at a southern station, as Cape Town, -Cordoba, or Melbourne. The base-line is practically a -north-and-south line; for though the two stations may not -lie in the same, or nearly the same, longitude, the displacement -determined is in reality that due to their difference of -latitude only, a correction being made for their difference -of longitude.</p> - -<p>The other method depends, not on displacement of -two observers north and south, or difference of latitude, but -on displacement east and west. Moreover, it does not -require that there shall be two observers at stations far -apart, but uses the observations made at one and the same -stations at different times. The earth, by turning on her -axis, carries the observer from the west to the east of an -imaginary line joining the earth’s centre and the centre of -Mars. When on the west of that line, or in the early evening, -he sees Mars displaced towards the east of the planet’s true -position. After nine or ten hours the observer is carried as -far to the east of that line, and sees Mars displaced towards -the west of his true position. Of course Mars has moved in -the interval. He is, in fact, in the midst of his retrograde -career. But the astronomer knows perfectly well how to -take that motion into account. Thus, by observing the two -displacements, or the total displacement of Mars from east -to west on account of the earth’s rotation, one and the same<span class="pagenum"><a id="Page_65">65</a></span> -observer can, in the course of a single favourable night, -determine the sun’s distance. And in passing, it may be -remarked that this is the only general method of which so -much can be said. By some of the others an astronomer -can, indeed, estimate the sun’s distance without leaving his -observatory—at least, theoretically he can do so. But many -years of observation would be required before he would have -materials for achieving this result. On the other hand, one -good pair of observations of Mars, in the evening and in the -morning, from a station near the equator, would give a very -fair measure of the sun’s distance. The reason why the -station should be near the equator will be manifest, if we -consider that at the poles there would be no displacement -due to rotation; at the equator the observer would be carried -round a circle some twenty-five thousand miles in circumference; -and the nearer his place to the equator the larger the -circle in which he would be carried, and (<i xml:lang="la" lang="la">cæteris paribus</i>) the -greater the evening and morning displacement of the planet.</p> - -<p>Both these methods have been successfully applied to -the problem of determining the sun’s distance, and both have -recently been applied afresh under circumstances affording -exceptionally good prospects of success, though as yet the -results are not known.</p> - -<p>It is, however, when we leave the direct surveying method -to which both the observations of Venus in transit and Mars -in opposition belong (in all their varieties), that the most -remarkable, and, one may say, unexpected methods of determining -the sun’s distance present themselves. Were not my -subject a wide one, I would willingly descant at length on the -marvellous ingenuity with which astronomers have availed -themselves of every point of vantage whence they might -measure the solar system. But, as matters actually stand, I -must be content to sketch these other methods very roughly, -only indicating their characteristic features.</p> - -<p>One of them is in some sense related to the method by -actual survey, only it takes advantage, not of the earth’s -dimensions, but of the dimensions of her orbit round the<span class="pagenum"><a id="Page_66">66</a></span> -common centre of gravity of herself and the moon. This -orbit has a diameter of about six thousand miles; and as -the earth travels round it, speeding swiftly onwards all the -time in her path round the sun, the effect is the same as -though the sun, in his apparent circuit round the earth, were -constantly circling once in a lunar month around a small -subordinate orbit of precisely the same size and shape as -that small orbit in which the earth circuits round the moon’s -centre of gravity. He appears then sometimes displaced -about 3000 miles on one side, sometimes about 3000 miles -on the other side of the place which he would have if our -earth were not thus perturbed by the moon. But astronomers -can note each day where he is, and thus learn by how -much he seems displaced from his mean position. Knowing -that his greatest displacement corresponds to so many miles -exactly, and noting what it seems to be, they learn, in fact, -how large a span of so many miles (about 3000) looks at the -sun’s distance. Thus they learn the sun’s distance precisely as -a rifleman learns the distance of a line of soldiers when he has -ascertained their apparent size—for only at a certain distance -can an object of known size have a certain apparent size.</p> - -<p>The moon comes in, in another way, to determine the -sun’s distance for us. We know how far away she is from -the earth, and how much, therefore, she approaches the sun -when new, and recedes from him when full. Calling this -distance, roughly, a 390th part of the sun’s, her distance -from him when new, her mean distance, and her distance -from him when full, are as the numbers 389, 390, 391. Now, -these numbers do not quite form a continued proportion, -though they do so very nearly (for 389 is to 390 as 390 to -391-1/400). If they were in exact proportion, the sun’s disturbing -influence on the moon when she is at her nearest would -be exactly equal to his disturbing influence on the moon -when at her furthest from him—or generally, the moon would -be exactly as much disturbed (on the average) in that half of -her path which lies nearer to the sun as in that half which -lies further from him. As matters are, there is a slight<span class="pagenum"><a id="Page_67">67</a></span> -difference. Astronomers can measure this difference; and -measuring it, they can ascertain what the actual numbers are -for which I have roughly given the numbers 389, 390, and -391; in other words, they can ascertain in what degree the -sun’s distance exceeds the moon’s. This is equivalent to -determining the sun’s distance, since the moon’s is already -known.</p> - -<p>Another way of measuring the sun’s distance has been -“favoured” by Jupiter and his family of satellites. Few -would have thought, when Römer first explained the delay -which occurs in the eclipse of these moons while Jupiter is -further from us than his mean distance, that that explanation -would lead up to a determination of the sun’s distance. But -so it happened. Römer showed that the delay is not in the -recurrence of the eclipses, but in the arrival of the news of -these events. From the observed time required by light to -traverse the extra distance when Jupiter is nearly at his -furthest from us, the time in which light crosses the distance -separating us from the sun is deduced; whence, if that distance -has been rightly determined, the velocity of light can be inferred. -If this velocity is directly measured in any way, and -found not to be what had been deduced from the adopted -measure of the sun’s distance, the inference is that the sun’s -distance has been incorrectly determined. Or, to put the -matter in another way, we know exactly how many minutes -and seconds light takes in travelling to us from the sun; if, -therefore, we can find out how fast light travels we know -how far away the sun is.</p> - -<p>But who could hope to measure a velocity approaching -200,000 miles in a second? At a first view the task seems -hopeless. Wheatstone, however, showed how it might be -accomplished, measuring by his method the yet greater -velocity of freely conducted electricity. Foucault and Fizeau -measured the velocity of light; and recently Cornu has made -more exact measurements. Knowing, then, how many miles -light travels in a second, and in how many seconds it comes -to us from the sun, we know the sun’s distance.</p> - -<p><span class="pagenum"><a id="Page_68">68</a></span> -The first of the methods which I here describe as -new methods must next be considered. It is one which -Leverrier regards as the method of the future. In fact, so -highly does he esteem it, that, on its account, he may almost -be said to have refused to sanction in any way the French -expeditions for observing the transit of Venus in 1874.</p> - -<p>The members of the sun’s family perturb each other’s -motions in a degree corresponding with their relative mass, -compared with each other and with the sun. Now, it can be -shown (the proof would be unsuitable to these pages,<a id="FNanchor_10" href="#Footnote_10" class="fnanchor">10</a> but -I have given it in my treatise on “The Sun”) that no change -in our estimate of the sun’s distance affects our estimate of -his mean density as compared with the earth’s. His substance -has a mean density equal to one-fourth of the earth’s, whether -he be 90 millions or 95 millions of miles from us, or indeed -whether he were ten millions or a million million miles from -us (supposing for a moment our measures did not indicate -his real distance more closely). We should still deduce from<span class="pagenum"><a id="Page_69">69</a></span> -calculation the same unvarying estimate of his mean density. -It follows that the nearer any estimate of his distance places -him, and therefore the smaller it makes his estimated -volume, the smaller also it makes his estimated mass, and -in precisely the same degree. The same is true of the -planets also. We determine Jupiter’s mass, for example (at -least, this is the simplest way), by noting how he swerves -his moons at their respective (estimated) distances. If we -diminish our estimate of their distances, we diminish at the -same time our estimate of Jupiter’s attractive power, and in -such degree, it may be shown (see note), as precisely to -correspond with our changed estimate of his size, leaving our -estimate of his mean density unaltered. And the same is -true for all methods of determining Jupiter’s mass. Suppose, -then, that, adopting a certain estimate of the scale of the -solar system, we find that the resulting estimate of the masses -of the planets and of the sun, <em>as compared with the earth’s -mass</em>, from their observed attractive influences on bodies -circling around them or passing near them, accords with -their estimated perturbing action as compared with the -earth’s,—then we should infer that our estimate of the sun’s -distance or of the scale of the solar system was correct. -But suppose it appeared, on the contrary, that the earth took -a larger or a smaller part in perturbing the planetary system -than, according to our estimate of her relative mass, she -should do,—then we should infer that the masses of the -other members of the system had been overrated or underrated; -or, in other words, that the scale of the solar system -had been overrated or underrated respectively. Thus we -should be able to introduce a correction into our estimate of -the sun’s distance.</p> - -<p>Such is the principle of the method by which Leverrier -showed that in the astronomy of the future the scale of the -solar system may be very exactly determined. Of course, the -problem is a most delicate one. The earth plays, in truth, -but a small part in perturbing the planetary system, and her -influence can only be distinguished satisfactorily (at present,<span class="pagenum"><a id="Page_70">70</a></span> -at any rate) in the case of the nearer members of the solar -family. Yet the method is one which, unlike others, will have -an accumulative accuracy, the discrepancies which are to test -the result growing larger as time proceeds. The method has -already been to some extent successful. It was, in fact, by -observing that the motions of Mercury are not such as can -be satisfactorily explained by the perturbations of the earth -and Venus according to the estimate of relative masses -deducible from the lately discarded value of the sun’s distance, -that Leverrier first set astronomers on the track of -the error affecting that value. He was certainly justified in -entertaining a strong hope that hereafter this method will -be exceedingly effective.</p> - -<p>We come next to a method which promises to be more -quickly if not more effectively available.</p> - -<p>Venus and Mars approach the orbit of our earth more -closely than any other planets, Venus being our nearest -neighbour on the one side, and Mars on the other. Looking -beyond Venus, we find only Mercury (and the mythical Vulcan), -and Mercury can give no useful information respecting -the sun’s distance. He could scarcely do so even if we -could measure his position among the stars when he is at -his nearest, as we can that of Mars; but as he can only then -be fairly seen when he transits the sun’s face, and as the sun -is nearly as much displaced as Mercury by change in the -observer’s station, the difference between the two displacements -is utterly insufficient for accurate measurement. But, -when we look beyond the orbit of Mars, we find certain -bodies which are well worth considering in connection with -the problem of determining the sun’s distance. I refer to -the asteroids, the ring of small planets travelling between -the paths of Mars and Jupiter, but nearer (on the whole<a id="FNanchor_11" href="#Footnote_11" class="fnanchor">11</a>) -to the path of Mars than to that of Jupiter.</p> - -<p><span class="pagenum"><a id="Page_71">71</a></span> -The asteroids present several important advantages over -even Mars and Venus.</p> - -<p>Of course, none of the asteroids approach so near to the -earth as Mars at his nearest. His least distance from the sun -being about 127 million miles, and the earth’s mean distance -about 92 millions, with a range of about a million and -a half on either side, owing to the eccentricity of her orbit, it -follows that he <em>may</em> be as near as some 35 million miles -(rather less in reality) from the earth when the sun, earth, -and Mars are nearly in a straight line and in that order. -The least distance of any asteroid from the sun amounts to -about 167 million miles, so that their least distance from the -earth cannot at any time be less than about 73,500,000 -miles, even if the earth’s greatest distance from the sun -corresponded with the least distance of one of these closely -approaching asteroids. This, by the way, is not very far from -being the case with the asteroid Ariadne, which comes within -about 169 million miles of the sun at her nearest, her place -of nearest approach being almost exactly in the same direction -from the sun as the earth’s place of greatest recession, -reached about the end of June. So that, whenever it so -chances that Ariadne comes into opposition in June, or that -the sun, earth, and Ariadne are thus placed—</p> - -<p class="center"> -Sun________Earth________Ariadne, -</p> - -<p class="p1 in0">Ariadne will be but about 75,500,000 miles from the earth. -Probably no asteroid will ever be discovered which approaches -the earth much more nearly than this; and this -approach, be it noticed, is not one which can occur in the -case of Ariadne except at very long intervals.</p> - -<p>But though we may consider 80 millions of miles as a -fair average distance at which a few of the most closely -approaching asteroids may be observed, and though this<span class="pagenum"><a id="Page_72">72</a></span> -distance seems very great by comparison with Mars’s occasional -opposition distance of 35 million miles, yet there are -two points in which asteroids have the advantage over -Mars. First, they are many, and several among them can -be observed under favourable circumstances; and in the -multitude of observations there is safety. In the second -place, which is the great and characteristic good quality of -this method of determining the sun’s distance, they do not -present a disc, like the planet Mars, but a small star-like -point. When we consider the qualities of the heliometric -method of measuring the apparent distance between -celestial objects, the advantage of points of light over discs -will be obvious. If we are measuring the apparent distance -between Mars and a star, we must, by shifting the movable -object-glass, bring the star’s image into apparent contact -with the disc-image of Mars, first on one side and then on -the other, taking the mean for the distance between the -centres. Whereas, when we determine the distance between -a star and an asteroid, we have to bring two star-like points -(one a star, the other the asteroid) into apparent coincidence. -We can do this in two ways, making the result so much the -more accurate. For consider what we have in the field of -view when the two halves of the object-glass coincide. -There is the asteroid and close by there is the star whose -distance we seek to determine in order to ascertain the -position of the asteroid on the celestial sphere. When the -movable half is shifted, the two images of star and asteroid -separate; and by an adjustment they can be made to -separate along the line connecting them. Suppose, then, -we first make the movable image of the asteroid travel away -from the fixed image (meaning by movable and fixed images, -respectively, those given by the movable and fixed halves of -the object-glass), towards the fixed image of the star—the -two points, like images, being brought into coincidence, we -have the measure of the distance between star and asteroid. -Now reverse the movement, carrying back the movable images -of the asteroid and star till they coincide again with their<span class="pagenum"><a id="Page_73">73</a></span> -fixed images. This movement gives us a second measure -of the distance, which, however, may be regarded as only a -reversed repetition of the preceding. But now, carrying on -the reverse motion, the moving images of star and asteroid -separate from their respective fixed images, the moving -image of the star drawing near to the fixed image of the -asteroid and eventually coinciding with it. Here we have a -third measure of the distance, which is independent of the -two former. Reversing the motion, and carrying the moving -images to coincidence with the fixed images, we have a -fourth measure, which is simply the third reversed. These -four measures will give a far more satisfactory determination -of the true apparent distance between the star and the -asteroid than can, under any circumstances, be obtained in -the case of Mars and a star. Of course, a much more exact -determination is required to give satisfactory measures of the -asteroid’s real distance from the earth in miles, for a much -smaller error would vitiate the estimate of the asteroid’s -distance than would vitiate to the same degree the estimate -of Mars’s distance: for the apparent displacements of the -asteroid as seen either from Northern and Southern stations, -or from stations east and west of the meridian, are very much -less than in the case of Mars, owing to his great proximity. -But, on the whole, there are reasons for believing that the advantage -derived from the nearness of Mars is almost entirely -counterbalanced by the advantage derived from the neatness -of the asteroid’s image. And the number of asteroids, with -the consequent power of repeating such measurements many -times for each occasion on which Mars has been thus observed, -seem to make the asteroids—so long regarded as -very unimportant members of the solar system—the bodies -from which, after all, we shall gain our best estimate of the -sun’s distance; that is, of the scale of the solar system.</p> - -<div class="tb">* <span class="in2">* </span><span class="in2">* </span><span class="in2">* </span><span class="in2">*</span></div> - -<p>Since the above pages were written, the results deduced -from the observations made by the British expeditions for<span class="pagenum"><a id="Page_74">74</a></span> -observing the transit of December 9, 1874, have been announced -by the Astronomer Royal. It should be premised -that they are not the results deducible from the entire series -of British observations, for many of them can only be used -effectively in combination with observations made by other -nations. For instance, the British observations of the duration -of the transit as seen from Southern stations are only -useful when compared with observations of the duration of -the transit as seen from Northern stations, and no British -observations of this kind were taken at Northern stations, or -could be taken at any of the British Northern stations -except one, where chief reliance was placed on photographic -methods. The only British results as yet “worked up” are -those which are of themselves sufficient, theoretically, to indicate -the sun’s distance, viz., those which indicated the epochs -of the commencement of transit as seen from Northern and -Southern stations, and those which indicated the epochs of -the end of transit as seen from such stations. The Northern -and Southern epochs of commencement compared together -suffice <em>of themselves</em> to indicate the sun’s distance; so also -do the epochs of the end of transit suffice <em>of themselves</em> for -that purpose. Such observations belong to the Delislean -method, which was the subject of so much controversy -for two or three years before the transit took place. -Originally it had been supposed that only observations by -that method were available, and the British plans were -formed upon that assumption. When it was shown that this -assumption was altogether erroneous, there was scarcely time -to modify the British plans so that of themselves they -might provide for the other or Halleyan method. But the -Southern stations which were suitable for that method were -strengthened; and as other nations, especially America and -Russia, occupied large numbers of Northern stations, the -Halleyan method was, in point of fact, effectually provided -for—a fortunate circumstance, as will presently be seen.</p> - -<p>The British operations, then, thus far dealt with, were -based on Delisle’s method; and as they were carried out<span class="pagenum"><a id="Page_75">75</a></span> -with great zeal and completeness, we may consider that -the result affords an excellent test of the qualities of this -method, and may supply a satisfactory answer to the questions -which were under discussion in 1872–74. Sir George -Airy, indeed, considers that the zeal and completeness with -which the British operations were carried out suffice to set -the result obtained from them above all others. But this -opinion is based rather on personal than on strictly scientific -grounds. It appears to me that the questions to be -primarily decided are whether the results are in satisfactory -agreement (i) <i xml:lang="la" lang="la">inter se</i> and (ii) with the general tenor of former -researches. In other words, while the Astronomer Royal -considers that the method and the manner of its application -must be considered so satisfactory that the results are to be -accepted unquestionably, it appears to me that the results -must be carefully questioned (as it were) to see whether the -method, and the observations by it, are satisfactory. In -the first place, the result obtained from Northern and -Southern observations of the commencement ought to agree -closely with the result obtained from Northern and Southern -observations of the end of transit. Unfortunately, they -differ rather widely. The sun’s distance by the former -observations comes out about one million miles greater -than the distance determined by the latter observations.</p> - -<p>This should be decisive, one would suppose. But it is -not all. The mean of the entire series of observations by -Delisle’s method comes out nearly one million miles greater -than the mean deduced by Professor Newcomb from many -entire series of observations by six different methods, all of -which may fairly be regarded as equal in value to Delisle’s, -while three are regarded by most astronomers as unquestionably -superior to it. Newcomb considers the probable -limits of error in his evaluation from so many combined -series of observations to be about 100,000 miles. Sir G. -Airy will allow no wider limits of error for the result of the -one series his observers have obtained than 200,000 miles. -Thus the greatest value admitted by Newcomb falls short<span class="pagenum"><a id="Page_76">76</a></span> -of the least value admitted by Sir G. Airy, by nearly 700,000 -miles.</p> - -<p>The obvious significance of this result should be, one -would suppose, that Delisle’s method is not quite so effective -as Sir G. Airy supposed; and the wide discordance between -the several results, of which the result thus deduced is the -mean, should prove this, one would imagine, beyond all -possibility of question. The Astronomer Royal thinks -differently, however. In his opinion, the wide difference -between his result and the mean of all the most valued -results by other astronomers, indicates the superiority of -Delisle’s method, not its inadequacy to the purpose for -which it has been employed.</p> - -<p>Time will shortly decide which of these views is correct; -but, for my own part, I do not hesitate to express my own -conviction that the sun’s distance lies very near the limits -indicated by Newcomb, and therefore is several hundred -thousand miles less than the minimum distance allowed by -the recently announced results.</p> - -<hr /> - -<p><span class="pagenum"><a id="Page_77">77</a></span></p> - -<div class="chapter"> -<h2><a id="DRIFTING_LIGHT-WAVES"></a>DRIFTING LIGHT-WAVES.</h2> -</div> - -<p class="in0">The method of measuring the motion of very swiftly -travelling bodies by noting changes in the light-waves which -reach us from them—one of the most remarkable methods -of observation ever yet devised by man—has recently been -placed upon its trial, so to speak; with results exceedingly -satisfactory to the students of science who had accepted the -facts established by it. The method will not be unfamiliar -to many of my readers. The principle involved was first -noted by M. Doppler, but not in a form which promised -any useful results. The method actually applied appears -to have occurred simultaneously to several persons, as well -theorists as observers. Thus Secchi claimed in March, -1868, to have applied it though unsuccessfully; Huggins -in April, 1868, described his successful use of the method. -I myself, wholly unaware that either of these observers was -endeavouring to measure celestial motions by its means, -described the method, in words which I shall presently -quote, in the number of <cite>Fraser’s Magazine</cite> for January, -1868, two months before the earliest enunciation of its -nature by the physicists just named.</p> - -<p>It will be well briefly to describe the principle of this -interesting method, before considering the attack to which it -has been recently subjected, and its triumphant acquittal -from defects charged against it. This brief description will -not only be useful to those readers who chance not to -be acquainted with the method, but may serve to remove -objections which suggest themselves, I notice, to many who<span class="pagenum"><a id="Page_78">78</a></span> -have had the principle of the method imperfectly explained -to them.</p> - -<p>Light travels from every self-luminous body in waves -which sweep through the ether of space at the rate of -185,000 miles per second. The whole of that region of -space over which astronomers have extended their survey, -and doubtless a region many millions of millions of times -more extended, may be compared to a wave-tossed sea, only -that instead of a wave-tossed surface, there is wave-tossed -space. At every point, through every point, along every -line, athwart every line, myriads of light-waves are at all -times rushing with the inconceivable velocity just mentioned.</p> - -<p>It is from such waves that we have learned all we know -about the universe outside our own earth. They bring to -our shores news from other worlds, though the news is not -always easy to decipher.</p> - -<p>Now, seeing that we are thus immersed in an ocean, -athwart which infinite series of waves are continually -rushing, and moreover that we ourselves, and every one of -the bodies whence the waves proceed either directly or after -reflection, are travelling with enormous velocity through this -ocean, the idea naturally presents itself that we may learn -something about these motions (as well as about the bodies -themselves whence they proceed), by studying the aspect of -the waves which flow in upon us in all directions.</p> - -<p>Suppose a strong swimmer who knew that, were he at -rest, a certain series of waves would cross him at a particular -rate—ten, for instance, in a minute—were to notice that -when he was swimming directly facing them, eleven passed -him in a minute: he would be able at once to compare -his rate of swimming with the rate of the waves’ motion. -He would know that while ten waves had passed him on -account of the waves’ motion, he had by his own motion -caused yet another wave to pass him, or in other words, had -traversed the distance from one wave-crest to the next -Thus he would know that his rate was one-tenth that of -the waves. Similarly if, travelling the same way as the waves,<span class="pagenum"><a id="Page_79">79</a></span> -he found that only nine passed him in a minute, instead -of ten.</p> - -<p>Again, it is not difficult to see that if an observer were at -rest, and a body in the water, which by certain motions -produced waves, were approaching or receding from the -observer, the waves would come in faster in the former case, -slower in the latter, than if the body were at rest. Suppose, -for instance, that some machinery at the bows of a ship -raised waves which, if the ship were at rest, would travel -along at the rate of ten a minute past the observer’s station. -Then clearly, if the ship approached him, each successive -wave would have a shorter distance to travel, and so would -reach him sooner than it otherwise would have done. -Suppose, for instance, the ship travelled one-tenth as fast as -the waves, and consider ten waves proceeding from her -bows—the first would have to travel a certain distance -before reaching the observer; the tenth, starting a minute -later, instead of having to travel the same distance, would -have to travel this distance diminished by the space over -which the ship had passed in one minute (which the -wave itself passes over in the tenth of a minute); instead, -then, of reaching the observer one minute after the other, it -would reach him nine-tenths of a minute after the first. -Thus it would seem to him as though the waves were -coming in faster than when the ship was at rest, in the -proportion of ten to nine, though in reality they would -be travelling at the same rate as before, only arriving in -quicker succession, because of the continual shortening of -the distance they had to travel, on account of the ship’s -approach. If he knew precisely how fast they <em>would</em> arrive -if the ship were at rest, and determined precisely how fast -they <em>did</em> arrive, he would be able to determine at once -the rate of the ship’s approach, at least the proportion -between her rate and the rate of the waves’ motion. -Similarly if, owing to the ship’s recession, the apparent rate -of the waves’ motion were reduced, it is obvious that the -actual change in the wave motion would not be a difference<span class="pagenum"><a id="Page_80">80</a></span> -of rate; but, in the case of the approaching ship, the -breadth from crest to crest would be reduced, while in -the case of a receding ship the distance from crest to crest -would be increased.</p> - -<p>If the above explanation should still seem to require -closer attention than the general reader may be disposed to -give, the following, suggested by a friend of mine—a very -skilful mathematician—will be found still simpler: Suppose -a stream to flow quite uniformly, and that at one place -on its banks an observer is stationed, while at another higher -up a person throws corks into the water at regular intervals, -say ten corks per minute; then these will float down and -pass the other observer, wherever he may be, at the rate of -ten per minute, <em>if</em> the cork-thrower is at rest. But if he -saunters either up-stream or down-stream, the corks will no -longer float past the other at the exact rate of ten per minute. -If the thrower is sauntering down-stream, then, between -throwing any cork and the next, he has walked a certain -way down, and the tenth cork, instead of having to travel -the same distance as the first before reaching the observer, -has a shorter distance to travel, and so reaches that observer -sooner. Or in fact, which some may find easier to see, this -cork will be nearer to the first cork than it would have been -if the thrower had remained still. The corks will lie at -equal distances from each other, but these equal distances -will be less than they would have been if the observer had -been at rest. If, on the contrary, the cork-thrower saunters -up-stream, the corks will be somewhat further apart than if -he had remained at rest. And supposing the observer to -know beforehand that the corks would be thrown in at the -rate of ten a minute, he would know, if they passed him at a -greater rate than ten a minute (or, in other words, at a less -distance from each other than the stream traversed in the -tenth of a minute), that the cork-thrower was travelling -down-stream or approaching him; whereas, if fewer than ten -a minute passed him, he would know that the cork-thrower -was travelling away from him, or up-stream. But also, if the<span class="pagenum"><a id="Page_81">81</a></span> -cork-thrower were at rest, and the observer moved up-stream—that -is, towards him—the corks would pass him at a -greater rate than ten a minute; whereas, if the observer were -travelling down-stream, or from the thrower, they would -pass him at a slower rate. If both were moving, it is easily -seen that if their movement brought them nearer together, -the number of corks passing the observer per minute would -be increased, whereas if their movements set them further -apart, the number passing him per minute would be -diminished.</p> - -<p>These illustrations, derived from the motions of water, -suffice in reality for our purpose. The waves which are -emitted by luminous bodies in space travel onwards like the -water-waves or the corks of the preceding illustrations. If -the body which emits them is rapidly approaching us, the -waves are set closer together or narrowed; whereas, if the -body is receding, they are thrown further apart or broadened. -And if we can in any way recognize such narrowing or -broadening of the light-waves, we know just as certainly that -the source of light is approaching us or receding from us (as -the case may be) as our observer in the second illustration -would know from the distance between the corks whether -his friend, the cork-thrower, was drawing near to him or -travelling away from him.</p> - -<p>But it may be convenient to give another illustration, -drawn from waves, which, like those of light, are not themselves -discernible by our senses—I refer to those aerial -waves of compression and rarefaction which produce what -we call sound. These waves are not only in this respect -better suited than water-waves to illustrate our subject, but -also because they travel in all directions through aerial space, -not merely along a surface. The waves which produce a -certain note, that is, which excite in our minds, through the -auditory nerve, the impression corresponding to a certain -tone, have a definite length. So long as the observer, and a -source of sound vibrating in one particular period, remain -both in the same place, the note is unchanged in tone, though<span class="pagenum"><a id="Page_82">82</a></span> -it may grow louder or fainter according as the vibrations -increase or diminish in amplitude. But if the source of -sound is approaching the hearer, the waves are thrown closer -together and the sound is rendered more acute (the longer -waves giving the deeper sound); and, on the other hand, if -the source of sound is receding from the hearer, the waves -are thrown further apart and the sound is rendered graver. -The <em>rationale</em> of these changes is precisely the same as that -of the changes described in the preceding illustrations. It -might, perhaps, appear that in so saying we were dismissing -the illustration from sound, at least as an independent one, -because we are explaining the illustration by preceding illustrations. -But in reality, while there is absolutely nothing -new to be said respecting the increase and diminution of -distances (as between the waves and corks of the preceding -illustration), the illustration from sound has the immense -advantage of admitting readily of experimental tests. It is -necessary only that the rate of approach or recession should -bear an appreciable proportion to the rate at which sound -travels. For waves are shortened or lengthened by approach -or recession by an amount which bears to the entire length -of the wave the same proportion which the rate of approach -or recession bears to the rate of the wave’s advance. Now -it is not very difficult to obtain rates of approach or recession -fairly comparable with the velocity of sound—about 364 -yards per second. An express train at full speed travels, let -us say, about 1800 yards per minute, or 30 yards per second. -Such a velocity would suffice to reduce all the sound-waves -proceeding from a bell or whistle upon the engine, by about -one-twelfth part, for an observer at rest on a station platform -approached by the engine. On the contrary, after the engine -had passed him, the sound-waves proceeding from the same -bell or whistle would be lengthened by one-twelfth. The -difference between the two tones would be almost exactly -three semitones. If the hearer, instead of being on a platform, -were in a train carried past the other at the same rate, -the difference between the tone of the bell in approaching<span class="pagenum"><a id="Page_83">83</a></span> -and its tone in receding would be about three tones. It -would not be at all difficult so to arrange matters, that while -two bells were sounding the same note—<i>Mi</i>, let us say—one -bell on one engine the other on the other, a traveller by one -should hear his own engine’s bell, the bell of the approaching -engine, and the bell of the same engine receding, as the -three notes—<i>Do</i>—<i>Mi</i>—<i>Sol</i>, whose wave-lengths are as the -numbers 15, 12, and 10. We have here differences very -easily to be recognized even by those who are not musicians. -Every one who travels much by train must have noticed how -the tone of a whistle changes as the engine sounding it travels -past. The change is not quite sharp, but very rapid, because -the other engine does not approach with a certain velocity -up to a definite moment and then recede with the same -velocity. It could only do this by rushing through the hearer, -which would render the experiment theoretically more exact -but practically unsatisfactory. As it rushes past instead of -through him, there is a brief time during which the rate of -approach is rapidly being reduced to nothing, followed by -a similarly brief time during which the rate of recession -gradually increases from nothing up to the actual rate of the -engines’ velocities added together.<a id="FNanchor_12" href="#Footnote_12" class="fnanchor">12</a> The change of tone -may be thus illustrated:—</p> - -<div id="ip_83" class="figcenter" style="max-width: 31.25em;"> - <img src="images/i_083.jpg" width="500" height="54" alt="" /></div> - -<p>A B representing the sound of the approaching whistle, B C -representing the rapid degradation of sound as the engine -rushes close past the hearer, and C D representing the sound -of the receding whistle. When a bell is sounded on the<span class="pagenum"><a id="Page_84">84</a></span> -engine, as in America, the effect is better recognized, as I -had repeated occasion to notice during my travels in that -country. Probably this is because the tone of a bell is in -any case much more clearly recognized than the tone of a -railway whistle. The change of tone as a clanging bell is -carried swiftly past (by the combined motions of both trains) -is not at all of such a nature as to require close attention for -its detection.</p> - -<p>However, the apparent variation of sound produced by -rapid approach or recession has been tested by exact experiments. -On a railway uniting Utrecht and Maarsen “were -placed,” the late Professor Nichol wrote, “at intervals of -something upwards of a thousand yards, three groups of -musicians, who remained motionless during the requisite -period. Another musician on the railway sounded at intervals -one uniform note; and its effects on the ears of the -stationary musicians have been fully published. From these, -certainly—from the recorded changes between grave and the -more acute, and <i xml:lang="la" lang="la">vice versâ</i>,—confirming, even <em>numerically</em>, -what the relative velocities might have enabled one to predict, -it appears justifiable to conclude that the general theory -is correct; and that the note of any sound may be greatly -modified, if not wholly changed, by the velocity of the individual -hearing it,” or, he should have added, by the velocity -of the source of sound: perhaps more correct than either, is -the statement that the note may be altered by the approach -or recession of the source of sound, whether that be caused -by the motion of the sounding body, or of the hearer himself, -or of both.</p> - -<p>It is difficult, indeed, to understand how doubt can exist -in the mind of any one competent to form an opinion on -the matter, though, as we shall presently see, some students -of science and one or two mathematicians have raised doubts -as to the validity of the reasoning by which it is shown that -a change should occur. That the reasoning is sound cannot, -in reality, be questioned, and after careful examination of -the arguments urged against it by one or two mathematicians,<span class="pagenum"><a id="Page_85">85</a></span> -I can form no other opinion than that these arguments -amount really but to an expression of inability to understand -the matter. This may seem astonishing, but is explained -when we remember that some mathematicians, by devoting -their attention too particularly to special departments, lose, -to a surprising degree, the power of dealing with subjects -(even mathematical ones) outside their department. Apart -from the soundness of the reasoning, the facts are unmistakably -in accordance with the conclusion to which the -reasoning points. Yet some few still entertain doubts, a -circumstance which may prove a source of consolation to -any who find themselves unable to follow the reasoning on -which the effects of approach and recession on wave-lengths -depend. Let such remember, however, that experiment in -the case of the aerial waves producing sound, accords perfectly -with theory, and that the waves which produce light -are perfectly analogous (so far as this particular point is concerned) -with the waves producing sound.</p> - -<p>Ordinary white light, and many kinds of coloured light, -may be compared with <em>noise</em>—that is, with a multitude of -intermixed sounds. But light of one pure colour may be -compared to sound of one determinate note. As the aerial -waves producing the effect of one definite tone are all of one -length, so the ethereal waves producing light of one definite -colour are all of one length. Therefore if we approach or -recede from a source of light emitting such waves, effects -will result corresponding with what has been described above -for the case of water-waves and sound-waves. If we approach -the source of light, or if it approaches us, the waves -will be shortened; if we recede from it, or if it recedes from -us, the waves will be lengthened. But the colour of light -depends on its wave-length, precisely as the tone of sound -depends on its wave-length. The waves producing red -light are longer than those producing orange light, these are -longer than the waves producing yellow light; and so the -wave-lengths shorten down from yellow to green, thence to -blue, to indigo, and finally to violet. Thus if a body shining<span class="pagenum"><a id="Page_86">86</a></span> -in reality with a pure green colour, approached the observer -with a velocity comparable with that of light, it would seem -blue, indigo, or violet, according to the rate of approach; -whereas if it rapidly receded, it would seem yellow, orange, -or red, according to the rate of recession.</p> - -<p>Unfortunately in one sense, though very fortunately in -many much more important respects, the rates of motion -among the celestial bodies are <em>not</em> comparable with the -velocity of light, but are always so much less as to be almost -rest by comparison. The velocity of light is about 187,000 -miles per second, or, according to the measures of the solar -system at present in vogue (which will shortly have to give -place to somewhat larger measures, the result of observations -made upon the recent transit of Venus), about 185,000 -miles per second. The swiftest celestial motion of which we -have ever had direct evidence was that of the comet of the -year 1843, which, at the time of its nearest approach to the -sun, was travelling at the rate of about 350 miles per second. -This, compared with the velocity of light, is as the motion -of a person taking six steps a minute, each less than half a -yard long, to the rush of the swiftest express train. No -body within our solar system can travel faster than this, the -motion of a body falling upon the sun from an infinite distance -being only about 370 miles per second when it reaches -his surface. And though swifter motions probably exist -among the bodies travelling around more massive suns than -ours, yet of such motions we can never become cognizant. -All the motions taking place among the stars themselves -would appear to be very much less in amount. The most -swiftly moving sun seems to travel but at the rate of about -50 or 60 miles per second.</p> - -<p>Now let us consider how far a motion of 100 miles per -second might be expected to modify the colour of pure -green light—selecting green as the middle colour of the -spectrum. The waves producing green light are of such a -length, that 47,000 of them scarcely equal in length a single -inch. Draw on paper an inch and divide it carefully into<span class="pagenum"><a id="Page_87">87</a></span> -ten equal parts, or take such parts from a well-divided rule; -divide one of these tenths into ten equal parts, as nearly as -the eye will permit you to judge; then one of these parts, or -about half the thickness of an average pin, would contain -475 of the waves of pure green light. The same length -would equal the length of 440 waves of pure yellow light, -and of 511 waves of pure blue light. (The green, yellow, -and blue, here spoken of, are understood to be of the -precise colour of the middle of the green, yellow, and blue -parts of the spectrum.) Thus the green waves must be -increased in the proportion of 475 to 440 to give yellow -light, or reduced in the proportion of 511 to 475 to give -blue light. For the first purpose, the velocity of recession -must bear to the velocity of light the proportion which 30 -bears to 475, or must be equal to rather more than one-sixteenth -part of the velocity of light—say 11,600 miles per -second. For the second purpose, the velocity of approach -must bear to the velocity of light the proportion which -36 bears to 475, or must be nearly equal to one-thirteenth -part of the velocity of light—say 14,300 miles per second. -But the motions of the stars and other celestial bodies, and -also the motions of matter in the sun, and so forth, are very -much less than these. Except in the case of one or two -comets (and always dismissing from consideration the -amazing apparent velocities with which comets’ tails <em>seem</em> to -be formed), we may take 100 miles per second as the -extreme limit of velocity with which we have to deal, in -considering the application of our theory to the motions of -recession and approach of celestial bodies. Thus in the -case of recession the greatest possible change of colour in -pure green light would be equivalent to the difference -between the medium green of the spectrum, and the colour -1-116th part of the way from medium green to medium -yellow; and in the case of approach, the change would correspond -to the difference between the medium green and -the colour 1-143rd part of the way from medium green to -medium blue. Let any one look at a spectrum of fair<span class="pagenum"><a id="Page_88">88</a></span> -length, or even at a correctly tinted painting of the solar -spectrum, and note how utterly unrecognizable to ordinary -vision is the difference of tint for even the twentieth part of -the distance between medium green and medium yellow on -one side or medium blue on the other, and he will recognize -how utterly hopeless it would be to attempt to appreciate -the change of colour due to the approach or recession -of a luminous body shining with pure green light and -moving at the tremendous rate of 100 miles per second. -It would be hopeless, even though we had the medium green -colour and the changed colour, either towards yellow or -towards blue, placed side by side for comparison—how -much more when the changed colour would have to be -compared with the observer’s recollection of the medium -colour, as seen on some other occasion!</p> - -<p>But this is the least important of the difficulties affecting -the application of this method by noting change of colour, -as Doppler originally proposed. Another difficulty, which -seems somehow to have wholly escaped Doppler’s attention, -renders the colour test altogether unavailable. We do not -get <em>pure</em> light from any of the celestial bodies except certain -gaseous clouds or nebulæ. From every sun we get, as from -our own sun, all the colours of the rainbow. There may be -an excess of some colours and a deficiency of others in any -star, so as to give the star a tint, or even a very decided -colour. But even a blood-red star, or a deep-blue or violet -star, does not shine with pure light, for the spectroscope -shows that the star has other colours than those producing -the prevailing tint, and it is only the great <em>excess</em> of red -rays (all kinds of red, too) or of blue rays (of all kinds), and -so on, which makes the star appear red, or blue, and so on, -to the eye. By far the greater number of stars or suns -show all the colours of the rainbow nearly equally distributed, -as in the case of our own sun. Now imagine for a -moment a white sun, which had been at rest, to begin suddenly -to approach us so rapidly (travelling more than 10,000 -miles per second) that the red rays became orange, the<span class="pagenum"><a id="Page_89">89</a></span> -orange became yellow, the yellow green, the green blue, -the blue indigo, the indigo violet, while the violet waves -became too short to affect the sense of sight. Then, <em>if that -were all</em>, that sun, being deprived of the red part of its -light, would shine with a slightly bluish tinge, owing to the -relative superabundance of rays from the violet end of the -spectrum. We should be able to recognize such a change, -yet not nearly so distinctly as if that sun had been shining -with a pure green light, and suddenly beginning to approach -us at the enormous rate just mentioned, changed in colour -to full blue. <em>Though</em>, if that sun were all the time approaching -us at the enormous rate imagined, we should be quite -unable to tell whether its slightly bluish tinge were due to -such motion of approach or to some inherent blueness in -the light emitted by the star. Similarly, if a white sun -suddenly began to recede so rapidly that its violet rays were -turned to indigo, the indigo to blue, and so on, the orange -rays turning to red, and the red rays disappearing altogether, -then, <em>if that were all</em>, its light would become slightly reddish, -owing to the relative superabundance of light from the -red end of the spectrum; and we might distinguish the -change, yet not so readily as if a sun shining with pure green -light began to recede at the same enormous rate, and so -shone with pure yellow light. <em>Though</em>, if that sun were all -the time receding at that enormous rate, we should be quite -unable to tell whether its slightly reddish hue were due to -such motion of recession or to some inherent redness in its -own lustre. <em>But in neither case would that be all.</em> In the -former, the red rays would indeed become orange; but the -rays beyond the red, which produce no effect upon vision, -would be converted into red rays, and fill up the part of the -spectrum deserted by the rays originally red. In the latter, -the violet rays would indeed become indigo; but the rays -beyond the violet, ordinarily producing no visible effect, -would be converted into violet rays, and fill up the part of -the spectrum deserted by the rays originally violet. Thus, -despite the enormous velocity of approach in one case and<span class="pagenum"><a id="Page_90">90</a></span> -of recession in the other, there would be no change whatever -in the colour of the sun in either case. All the colours of -the rainbow would still be present in the sun’s light, and it -would therefore still be a white sun.</p> - -<p>Doppler’s method would thus fail utterly, even though -the stars were travelling hither and thither with motions -a hundred times greater than the greatest known stellar -motions.</p> - -<p>This objection to Doppler’s theory, as originally proposed, -was considered by me in an article on “Coloured Suns” in -<cite>Fraser’s Magazine</cite> for January, 1868. His theory, indeed, -was originally promulgated not as affording a means of -measuring stellar motions, but as a way of accounting for -the colours of double stars. It was thus presented by -Professor Nichol, in a chapter of his “Architecture of the -Heavens,” on this special subject:—“The rapid motion of -light reaches indeed one of those numbers which reason -owns, while imagination ceases to comprehend them; but it -is also true that the swiftness with which certain individuals -of the double stars sweep past their perihelias, or rather -their periasters, is amazing; and in this matter of colours, it -must be recollected that the question solely regards the -difference between the velocities of the waves constituent of -colours, at those different stellar positions. Still it is a bold—even -a magnificent idea; and if it can be reconciled with -the permanent colours of the multitude of stars surrounding -us—stars which too are moving in great orbits with immense -velocities—it may be hailed almost as a positive discovery. -It must obtain confirmation, or otherwise, so soon as we can -compare with certainty the observed colorific changes of -separate systems with the known fluctuations of their orbital -motions.”</p> - -<p>That was written a quarter of a century ago, when spectroscopic -analysis, as we now know it, had no existence. -Accordingly, while the fatal objection to Doppler’s original -theory is overlooked on the one hand, the means of applying -the principle underlying the theory, in a much more exact<span class="pagenum"><a id="Page_91">91</a></span> -manner than Doppler could have hoped for, is overlooked -on the other. Both points are noted in the article above -referred to, in the same paragraph. “We may dismiss,” I -there stated, “the theory started some years ago by the -French astronomer, M. Doppler.” But, I presently added, -“It is quite clear that the effects of a motion rapid enough -to produce such a change” (<i>i.e.</i> a change of tint in a pure -colour) “would shift the position of the whole spectrum—and -this change would be readily detected by a reference to -the spectral lines.” This is true, even to the word “readily.” -Velocities which would produce an appreciable change of -tint would produce “readily” detectible changes in the position -of the spectral lines; the velocities actually existing -among the star-motions would produce changes in the position -of these lines detectible only with extreme difficulty, or -perhaps in the majority of instances not detectible at all.</p> - -<p>It has been in this way that the spectroscopic method -has actually been applied.</p> - -<p>It is easy to perceive the essential difference between this -way of applying the method and that depending on the -attempted recognition of changes of colour. A dark line in -the spectrum marks in reality the place of a missing tint. -The tints next to it on either side are present, but the tint -between them is wanting. They are changed in colour—very -slightly, in fact quite inappreciably—by motions of recession -or approach, or, in other words, they are shifted in -position along the spectrum, towards the red end for recession, -towards the violet end for approach; and of course the -dark space between is shifted along with them. One may -say that the missing tint is changed. For in reality that is -precisely what would happen. If the light of a star at rest -gave every tint of the spectrum, for instance, except mid-green -alone, and that star approached or receded so swiftly -that its motion would change pure green light to pure yellow -in one case, or pure blue in the other, then the effect on the -spectrum of such a star would be to throw the dark line -from the middle of the green part of the spectrum to the<span class="pagenum"><a id="Page_92">92</a></span> -middle of the yellow part in one case, or to the middle of -the blue part in the other. The dark line would be quite -notably shifted in either case. With the actual stellar -motions, though all the lines are more or less shifted, the -displacement is always exceedingly minute, and it becomes -a task of extreme difficulty to recognize, and still more to -measure, such displacement.</p> - -<p>When I first indicated publicly (January, 1868) the way -in which Doppler’s principle could alone be applied, two -physicists, Huggins in England and Secchi in Italy, were -actually endeavouring, with the excellent spectroscopes in -their possession, to apply this method. In March, 1868, -Secchi gave up the effort as useless, publicly announcing the -plan on which he had proceeded and his failure to obtain -any results except negative ones. A month later Huggins -also publicly announced the plan on which he had been -working, but was also able to state that in one case, that of -the bright star Sirius, he had succeeded in measuring a motion -in the line of sight, having discovered that Sirius was receding -from the earth at the rate of 41·4 miles per second. I say -was receding, because a part of the recession at the time of -observation was due to the earth’s orbital motion around the -sun. I had, at his request, supplied Huggins with the -formula for calculating the correction due to this cause, and, -applying it, he found that Sirius is receding from the sun at -the rate of about 29½ miles per second, or some 930 millions -of miles per annum.</p> - -<p>I am not here specially concerned to consider the actual -results of the application of this method since the time of -Huggins’s first success; but the next chapter of the history -of the method is one so interesting to myself personally that -I feel tempted briefly to refer to details. So soon as I had -heard of Huggins’s success with Sirius, and that an instrument -was being prepared for him wherewith he might hope to -extend the method to other stars, I ventured to make a -prediction as to the result which he would obtain whensoever -he should apply it to five stars of the seven forming the so-<span class="pagenum"><a id="Page_93">93</a></span>called -Plough. I had found reason to feel assured that these -five form a system drifting all together amid stellar space. -Satisfied for my own part as to the validity of the evidence, -I submitted it to Sir J. Herschel, who was struck by its force. -The apparent drift of those stars was, of course, a thwart -drift; but if they really were drifting in space, then their -motions in the line of sight must of necessity be alike. My -prediction, then, was that whensoever Huggins applied to -those stars the new method he would find them either all -receding at the same rate, or all approaching at the same rate, -or else that all <em>alike</em> failed to give any evidence at all either -of recession or approach. I had indicated the five in the -first edition of my “Other Worlds”—to wit, the stars of the -Plough, omitting the nearest “pointer” to the pole and the -star marking the third horse (or the tip of the Great Bear’s -tail). So soon as Huggins’s new telescope and its spectroscopic -adjuncts were in working order, he re-examined Sirius, -determined the motions of other stars; and at last on one -suitable evening he tested the stars of the Plough. He -began with the nearest pointer, and found that star swiftly -approaching the earth. He turned to the other pointer, and -found it rapidly receding from the earth. Being under the -impression that my five included both pointers, he concluded -that my prediction had utterly failed, and so went on with -his observations, altogether unprejudiced in its favour, to say -the least. The next star of the seven he found to be receding -at the same rate as the second pointer; the next at the -same rate, the next, and the next receding still at the same -rate, and lastly the seventh receding at a different rate. -Here, then, were five stars all receding at a common rate, -and of the other two one receding at a different rate, the -other swiftly approaching. Turning next to the work containing -my prediction, Huggins found that the five stars thus -receding at a common rate were the five whose community -of motion I had indicated two years before. Thus the first -prediction ever made respecting the motions of the so-called -fixed stars was not wanting in success. I would venture to<span class="pagenum"><a id="Page_94">94</a></span> -add that the theory of star-drift, on the strength of which -the prediction was made, was in effect demonstrated by the -result.</p> - -<p>The next application of the new method was one of -singular interest. I believe it was Mr. Lockyer who first -thought of applying the method to measure the rate of solar -hurricanes as well as the velocities of the uprush and downrush -of vaporous matter in the atmosphere of the sun. -Another spectroscopic method had enabled astronomers to -watch the rush of glowing matter from the edge of the sun, -by observing the coloured flames and their motions; but by -the new method it was possible to determine whether the -flames at the edge were swept by solar cyclones carrying -them from or towards the eye of the terrestrial observer, -and also to determine whether glowing vapours over the -middle of the visible disc were subject to motion of uprush, -which of course would carry them towards the eye, or of -downrush, which would carry them from the eye. The -result of observations directed to this end was to show -that at least during the time when the sun is most spotted, -solar hurricanes of tremendous violence take place, while -the uprushing and downrushing motions of solar matter -sometimes attain a velocity of more than 100 miles per -second.</p> - -<p>It was this success on the part of an English spectroscopist -which caused that attack on the new method against -which it has but recently been successfully defended, at -least in the eyes of those who are satisfied only by experimental -tests of the validity of a process. The Padre -Secchi had failed, as we have seen, to recognize motions -of recession and approach among the stars by the new -method. But he had taken solar observation by spectroscopic -methods under his special charge, and therefore -when the new results reached his ears he felt bound to -confirm or invalidate them. He believed that the apparent -displacement of dark lines in the solar spectrum might be -due to the heat of the sun causing changes in the delicate<span class="pagenum"><a id="Page_95">95</a></span> -adjustments of the instrument—a cause of error against -which precautions are certainly very necessary. He satisfied -himself that when sufficient precautions are taken no displacements -take place such as Lockyer, Young, and others -claimed to have seen. But he submitted the matter to a -further test. As the sun is spinning swiftly on his axis, -his mighty equator, more than two and a half millions of -miles in girth, circling once round in about twenty-four -days, it is clear that on one side the sun’s surface is swiftly -moving <em>towards</em>, and on the other side as swiftly moving -<em>from</em>, the observer. By some amazing miscalculation, Secchi -made the rate of this motion 20 miles per second, so that -the sum of the two motions in opposite directions would -equal 40 miles per second. He considered that he ought -to be able by the new method, if the new method is -trustworthy at all, to recognize this marked difference -between the state of the sun’s eastern and western edges; -he found on trial that he could not do so; and accordingly -he expressed his opinion that the new method is not trustworthy, -and that the arguments urged in its favour are -invalid.</p> - -<p>The weak point in his reasoning resided in the circumstance -that the solar equator is only moving at the -rate of about 1¼ miles per second, so that instead of a -difference of 40 miles per second between the two edges, -which should be appreciable, the actual difference (that is, -the sum of the two equal motions in opposite directions) -amounts only to 2½ miles per second, which certainly -Secchi could not hope to recognize with the spectroscopic -power at his disposal. Nevertheless, when the error in his -reasoning was pointed out, though he admitted that error, -he maintained the justice of his conclusion; just as Cassini, -having mistakenly reasoned that the degrees of latitude -should diminish towards the pole instead of increasing, and -having next mistakenly found, as he supposed, that they do -diminish, acknowledged the error of his reasoning, but -insisted on the validity of his observations,—maintaining<span class="pagenum"><a id="Page_96">96</a></span> -thenceforth, as all the world knows, that the earth is extended -instead of flattened at the poles.</p> - -<p>Huggins tried to recognize by the new method the -effects of the sun’s rotation, using a much more powerful -spectroscope than Secchi’s. The history of the particular -spectroscope he employed is in one respect specially interesting -to myself, as the extension of spectroscopic power -was of my own devising before I had ever used or even -seen a powerful spectroscope. The reader is aware that -spectroscopes derive their light-sifting power from the prisms -forming them. The number of prisms was gradually increased, -from Newton’s single prism to Fraunhofer’s pair, -and to Kirchhoff’s battery of four, till six were used, -which bent the light round as far as it would go. Then -the idea occurred of carrying the light to a higher level -(by reflections) and sending it back through the same -battery of prisms, doubling the dispersion. Such a battery, -if of six prisms, would spread the spectral colours twice -as widely apart as six used in the ordinary way, and would -thus have a dispersive power of twelve prisms. It occurred -to me that after taking the rays through six prisms, arranged -in a curve like the letter C, an intermediate four-cornered -prism of a particular shape (which I determined) might be -made to send the rays into another battery of six prisms, the -entire set forming a double curve like the letter S, the rays -being then carried to a higher level and back through the -double battery. In this way a dispersive power of nineteen -prisms could be secured. My friend, Mr. Browning, the -eminent optician, made a double battery of this kind,<a id="FNanchor_13" href="#Footnote_13" class="fnanchor">13</a><span class="pagenum"><a id="Page_97">97</a></span> -which was purchased by Mr. W. Spottiswoode, and by him -lent to Mr. Huggins for the express purpose of dealing with -the task Secchi had set spectroscopists. It did not, however, -afford the required evidence. Huggins considered the -displacement of dark lines due to the sun’s rotation to be -recognizable, but so barely that he could not speak confidently -on the point.</p> - -<p>There for a while the matter rested. Vögel made observations -confirming Huggins’s results relative to stellar -motions; but Vögel’s instrumental means were not sufficiently -powerful to render his results of much weight.</p> - -<p>But recently two well-directed attacks have been made -upon this problem, one in England, the other in America, -and in both cases with success. Rather, perhaps, seeing -that the method had been attacked and was supposed to -require defence, we may say that two well-directed assaults -have been made upon the attacking party, which has been -completely routed.</p> - -<p>Arrangements were made not very long ago, by which -the astronomical work of Greenwich Observatory, for a long -time directed almost exclusively to time observations, should -include the study of the sun, stars, planets, and so forth. -Amongst other work which was considered suited to the -National Observatory was the application of spectroscopic -analysis to determine motions of recession and approach -among the celestial bodies. Some of these observations, -by the way, were made, we are told, “to test the truth -of Doppler’s principle,” though it seems difficult to suppose -for an instant that mathematicians so skilful as the chief -of the Observatory and some of his assistants could entertain -any doubt on that point. Probably it was intended -by the words just quoted to imply simply that some of -the observations were made for the purpose of illustrating -the principle of the method. We are not to suppose that -on a point so simple the Greenwich observers have been in -any sort of doubt.</p> - -<p>At first their results were not very satisfactory. The<span class="pagenum"><a id="Page_98">98</a></span> -difficulties which had for a long time foiled Huggins, and -which Secchi was never able to master, rendered the first -Greenwich measures of stellar motions in the line of sight -wildly inconsistent, not only with Huggins’s results, but with -each other.</p> - -<p>Secchi was not slow to note this. He renewed his objections -to the new method of observation, pointing and illustrating -them by referring to the discrepancies among the -Greenwich results. But recently a fresh series of results has -been published, showing that the observers at Greenwich -have succeeded in mastering some at least among the difficulties -which they had before experienced. The measurements -of star-motions showed now a satisfactory agreement -with Huggins’s results, and their range of divergence among -themselves was greatly reduced. The chief interest of the -new results, however, lay in the observations made upon -bodies known to be in motion in the line of sight at rates -already measured. These observations, though not wanted -as tests of the accuracy of the principle, were very necessary -as tests of the qualities of the instruments used in applying -it. It is here and thus that Secchi’s objections alone required -to be met, and here and thus they have been -thoroughly disposed of. Let us consider what means exist -within the solar system for thus testing the new method.</p> - -<p>The earth travels along in her orbit at the rate of about -18⅓ miles in every second of time. Not to enter into niceties -which could only properly be dealt with mathematically, -it may be said that with this full velocity she is at times -approaching the remoter planets of the system, and at times -receding from them; so that here at once is a range of difference -amounting to about 37 miles per second, and fairly -within the power of the new method of observation. For -it matters nothing, so far as the new method is concerned, -whether the earth is approaching another orb by her motion, -or that orb approaching by its own motion. Again, the -plant Venus travels at the rate of about 21½ miles per -second, but as the earth travels only 3 miles a second less<span class="pagenum"><a id="Page_99">99</a></span> -swiftly, and the same way round, only a small portion of -Venus’s motion ever appears as a motion of approach towards -or recession from the earth. Still, Venus is sometimes -approaching and sometimes receding from the earth, -at a rate of more than 8 miles per second. Her light is -much brighter than that of Jupiter or Saturn, and accordingly -this smaller rate of motion would be probably more -easily recognized than the greater rate at which the giant -planets are sometimes approaching and at other times -receding from the earth. At least, the Greenwich observers -seem to have confined their attention to Venus, -so far as motions of planets in the line of sight are concerned. -The moon, as a body which keeps always at -nearly the same distance from us, would of course be the -last in the world to be selected to give positive evidence -in favour of the new method; but she serves to afford a -useful test of the qualities of the instruments employed. -If when these were applied to her they gave evidence of -motions of recession or approach at the rate of several miles -per second, when we know as a matter of fact that the -moon’s distance never<a id="FNanchor_14" href="#Footnote_14" class="fnanchor">14</a> varies by more than 30,000 miles -during the lunar month, her rate of approach or recession -thus averaging about one-fiftieth part of a mile per second, -discredit would be thrown on the new method—not, indeed, -as regards its principle, which no competent reasoner can -for a moment question, but as regards the possibility of -practically applying it with our present instrumental means.</p> - -<p>Observations have been made at Greenwich, both on -Venus and on the moon, by the new method, with results -entirely satisfactory. The method shows that Venus is -receding when she is known to be receding, and that she -is approaching when she is known to be approaching. Again, -the method shows no signs of approach or recession in the -moon’s case. It is thus in satisfactory agreement with the<span class="pagenum"><a id="Page_100">100</a></span> -known facts. Of course these results are open to the objection -that the observers have known beforehand what to -expect, and that expectation often deceives the mind, -especially in cases where the thing to be observed is not -at all easy to recognize. It will presently be seen that the -new method has been more satisfactorily tested, in this -respect, in other ways. It may be partly due to the effect -of expectation that in the case of Venus the motions of -approach and recession, tested by the new method, have -always been somewhat too great. A part of the excess -may be due to the use of the measure of the sun’s distance, -and therefore the measures of the dimensions of the solar -system, in vogue before the recent transit. These measures -fall short to some degree of those which result from the -observations made in December, 1874, on Venus in transit, -the sun’s distance being estimated at about 91,400,000 miles -instead of 92,000,000 miles, which would seem to be nearer -the real distance. Of course all the motions within the -solar system would be correspondingly under-estimated. On -the other hand, the new method would give all velocities -with absolute correctness if instrumental difficulties could -be overcome. The difference between the real velocities -of Venus approaching and receding, and those calculated -according to the present inexact estimate of the sun’s distance, -is however much less than the observed discrepancy, -doubtless due to the difficulties involved in the application -of this most difficult method. I note the point, chiefly for -the sake of mentioning the circumstance that theoretically -the method affords a new means of measuring the dimensions -of the solar system. Whensoever the practical application -of the method has been so far improved that the -rate of approach or recession of Venus, or Mercury, or -Jupiter, or Saturn (any one of these planets), can be -determined on any occasion, with great nicety, we can at -once infer the sun’s distance with corresponding exactness. -Considering that the method has only been invented -ten years (setting aside Doppler’s first vague ideas respecting -it), and that spectroscopic analysis as a method of exact<span class="pagenum"><a id="Page_101">101</a></span> -observation is as yet little more than a quarter of a century -old, we may fairly hope that in the years to come the new -method, already successfully applied to measure motions of -recession and approach at the rate of 20 or 30 miles per -second, will be employed successfully in measuring much -smaller velocities. Then will it give us a new method of -measuring the great base-line of astronomical surveying—the -distance of our world from the centre of the solar -system.</p> - -<p>That this will one day happen is rendered highly probable, -in my opinion, by the successes next to be related.</p> - -<p>Besides the motions of the planets around the sun, there -are their motions of rotation, and the rotation of the sun -himself upon his axis. Some among these turning motions -are sufficiently rapid to be dealt with by the new method. -The most rapid rotational motion with which we are -acquainted from actual observation is that of the planet -Jupiter. The circuit of his equator amounts to about -267,000 miles, and he turns once on his axis in a few minutes -less than ten hours, so that his equatorial surface travels at -the rate of about 26,700 miles an hour, or nearly 7½ miles -per second. Thus between the advancing and retreating -sides of the equator there is a difference of motion in the -line of sight amounting to nearly 15 miles. But this is not -all. Jupiter shines by reflecting sunlight. Now it is easily -seen that where his turning equator <em>meets</em> the waves of light -from the sun, these are shortened, in the same sense that -waves are shortened for a swimmer travelling to meet them, -while these waves, already shortened in this way, are further -shortened when starting from the same advancing surface -of Jupiter, on their journey to us after reflection. In this -way the shortening of the waves is doubled, at least when -the earth is so placed that Jupiter lies in the same direction -from us as from the sun, the very time, in fact, when Jupiter -is most favourably placed for ordinary observation, or is at his -highest due south, when the sun is at his lowest below the -northern horizon—that is, at midnight. The lengthening<span class="pagenum"><a id="Page_102">102</a></span> -of the waves is similarly doubled at this most favourable -time for observation; and the actual difference between the -motion of the two sides of Jupiter’s equator being nearly -15 miles per second, the effect on the light-waves is -equivalent to that due to a difference of nearly 30 miles -per second. Thus the new method may fairly be expected -to indicate Jupiter’s motion of rotation. The Greenwich -observers have succeeded in applying it, though Jupiter has -not been favourably situated for observation. Only on one -occasion, says Sir G. Airy, was the spectrum of Jupiter -“seen fairly well,” and on that occasion “measures were -obtained which gave a result in remarkable agreement with -the calculated value.” It may well be hoped that when in -the course of a few years Jupiter returns to that part of his -course where he rises high above the horizon, shining more -brightly and through a less perturbed air, the new method -will be still more successfully applied. We may even hope -to see it extended to Saturn, not merely to confirm the -measures already made of Saturn’s rotation, but to resolve -the doubts which exist as to the rotation of Saturn’s ring-system.</p> - -<p>Lastly, there remains the rotation of the sun, a movement -much more difficult to detect by the new method, -because the actual rate of motion even at the sun’s equator -amounts only to about 1 mile per second.</p> - -<p>In dealing with this very difficult task, the hardest which -spectroscopists have yet attempted, the Greenwich observers -have achieved an undoubted success; but unfortunately for -them, though fortunately for science, another observatory, -far smaller and of much less celebrity, has at the critical -moment achieved success still more complete.</p> - -<p>The astronomers at our National Observatory have been -able to recognize by the new method the turning motion of -the sun upon his axis. And here we have not, as in the -case of Venus, to record merely that the observers have -seen what they expected to see because of the known -motion of the sun. “Particular care was taken,” says<span class="pagenum"><a id="Page_103">103</a></span> -Airy, “to avoid any bias from previous knowledge of the -direction in which a displacement” (of the spectral lines) -“was to be expected,” the side of the sun under observation -not being known by the observer until after the -observation was completed.</p> - -<p>But Professor Young, at Dartmouth College, Hanover, -N.H., has done much more than merely obtain evidence by -the new method that the sun is rotating as we already knew. -He has succeeded so perfectly in mastering the instrumental -and observational difficulties, as absolutely to be -able to rely on his <em>measurement</em> (as distinguished from the -mere recognition) of the sun’s motion of rotation. The -manner in which he has extended the powers of ordinary -spectroscopic analysis, cannot very readily be described in -these pages, simply because the principles on which the -extension depends require for their complete description -a reference to mathematical considerations of some complexity. -Let it be simply noted that what is called the -diffraction spectrum, obtained by using a finely lined plate, -results from the dispersive action of such a plate, or <em>grating</em> -as it is technically called, and this dispersive power can be -readily combined with that of a spectroscope of the ordinary -kind. Now Dr. Rutherfurd, of New York, has succeeded -in ruling so many thousand lines on glass within the breadth -of a single inch as to produce a grating of high dispersive -power. Availing himself of this beautiful extension of -spectroscopic powers, Professor Young has succeeded in -recognizing effects of much smaller motions of recession -and approach than had before been observable by the -new method. He has thus been able to measure the -rotation-rate of the sun’s equatorial regions. His result -exceeds considerably that inferred from the telescopic observation -of the solar spots. For whereas from the motion of -the spots a rotation-rate of about 1¼ mile per second has -been calculated for the sun’s equator, Professor Young -obtains from his spectroscopic observations a rate of rather -more than 1⅖ mile, or about 300 yards per second more -than the telescopic rate.</p> - -<p><span class="pagenum"><a id="Page_104">104</a></span> -If Young had been measuring the motion of the same -matter which is observed with the telescope, there could of -course be no doubt that the telescope was right and the -spectroscope wrong. We might add a few yards per second -for the probably greater distance of the sun resulting from -recent transit observations. For of course with an increase -in our estimate of the sun’s distance there comes an increase -in our estimate of the sun’s dimensions, and of the velocity -of the rotational motion of his surface. But only about -12 yards per second could be allowed on this account; -the rest would have to be regarded as an error due to the -difficulties involved in the spectroscopic method. In reality, -however, the telescopist and the spectroscopist observe -different things in determining by their respective methods -the sun’s motion of rotation. The former observes the -motion of the spots belonging to the sun’s visible surface; -the latter observes the motion of the glowing vapours outside -that surface, for it is from these vapours, not from the -surface of the sun, that the dark lines of the spectrum -proceed. Now so confident is Professor Young of the -accuracy of his spectroscopic observations, that he is -prepared to regard the seeming difference of velocity -between the atmosphere and surface of the sun as real. -He believes that “the solar atmosphere really sweeps -forward over the underlying surface, in the same way that -the equatorial regions outstrip the other parts of the sun’s -surface.” This inference, important and interesting in itself, -is far more important in what it involves. For if we can -accept it, it follows that the spectroscopic method of -measuring the velocity of motions in the line of sight -is competent, under favourable conditions, to obtain results -accurate within a few hundred yards per second, or 10 or -12 miles per minute. If this shall really prove to be -true for the method now, less than ten years after it -was first successfully applied, what may we not hope from -the method in future years? Spectroscopic analysis itself -is in its infancy, and this method is but a recent application<span class="pagenum"><a id="Page_105">105</a></span> -of spectroscopy. A century or so hence astronomers will -smile (though not disdainfully) at these feeble efforts, much -as we smile now in contemplating the puny telescopes -with which Galileo and his contemporaries studied the -star-depths. And we may well believe that largely as the -knowledge gained by telescopists in our own time surpasses -that which Galileo obtained, so will spectroscopists a few -generations hence have gained a far wider and deeper -insight into the constitution and movements of the stellar -universe than the spectroscopists of our own day dare even -hope to attain.</p> - -<p>I venture confidently to predict that, in that day, astronomers -will recognize in the universe of stars a variety -of structure, a complexity of arrangement, an abundance -of every form of cosmical vitality, such as I have been led -by other considerations to suggest, not the mere cloven -lamina of uniformly scattered stars more or less resembling -our sun, and all in nearly the same stage of cosmical development, -which the books of astronomy not many years -since agreed in describing. The history of astronomical progress -does not render it probable that the reasoning already -advanced, though in reality demonstrative, will convince the -generality of science students until direct and easily understood -observations have shown the real nature of the constitution -of that part of the universe over which astronomical -survey extends. But the evidence already obtained, though -its thorough analysis may be “<i xml:lang="fr" lang="fr">caviare</i> to the general,” suffices -to show the real nature of the relations which one day will -come within the direct scope of astronomical observation.</p> - -<hr /> - -<p><span class="pagenum"><a id="Page_106">106</a></span></p> - -<div class="chapter"> -<h2><a id="THE_NEW_STAR_WHICH_FADED_INTO_STAR-MIST"></a><i>THE NEW STAR WHICH FADED INTO STAR-MIST.</i></h2> -</div> - -<p class="in0">The appearance of a new star in the constellation of the -Swan in the autumn of 1876 promises to throw even more -light than was expected on some of the most interesting -problems with which modern astronomy has to deal. It -was justly regarded as a circumstance of extreme interest -that so soon after the outburst of the star which formed -a new gem in the Northern Crown in May, 1866, another -should have shone forth under seemingly similar conditions. -And when, as time went on, it appeared that in several -respects the new star in the Swan differed from the new star -in the Crown, astronomers found fresh interest in studying, -as closely as possible, the changes presented by the former -as it gradually faded from view. But they were not prepared -to expect what has actually taken place, or to recognize so -great a difference of character between these two new stars, -that whereas one seemed throughout its visibility to ordinary -eyesight, and even until the present time, to be justly called -a star, the other should so change as to render it extremely -doubtful whether at any time it deserved to be regarded as a -star or sun.</p> - -<p>Few astronomical phenomena, even of those observed -during this century (so fruitful in great astronomical discoveries), -seem better worthy of thorough investigation and -study than those presented by the two stars which appeared -in the Crown and in the Swan, in 1866 and 1876 respectively.<span class="pagenum"><a id="Page_107">107</a></span> -A new era seems indeed to be beginning for those -departments of astronomy which deal with stars and star-cloudlets -on the one hand, and with the evolution of solar -systems and stellar systems on the other.</p> - -<p>Let us briefly consider the history of the star of 1866 in -the first place, and then turn our thoughts to the more -surprising and probably more instructive history of the star -which shone out in November, 1876.</p> - -<p>In the first place, however, I would desire to make a few -remarks on the objections which have been expressed by an -observer to whom astronomy is indebted for very useful -work, against the endeavour to interpret the facts ascertained -respecting these so-called new stars. M. Cornu, who made -some among the earliest spectroscopic observations of the -star in Cygnus, after describing his results, proceeded as -follows:—“Grand and seductive though the task may be -of endeavouring to draw from observed facts inductions -respecting the physical state of this new star, respecting its -temperature, and the chemical reactions of which it may be -the scene, I shall abstain from all commentary and all hypothesis -on this subject. I think that we do not yet possess -the data necessary for arriving at useful conclusions, or at -least at conclusions capable of being tested: however -attractive hypotheses may be, we must not forget that -they are outside the bounds of science, and that, far from -serving science, they seriously endanger its progress.” This, -as I ventured to point out at the time, is utterly inconsistent -with all experience. M. Cornu’s objection to theorizing -when he did not see his way to theorizing justly, is sound -enough; but his general objection to theorizing is, with all -deference be it said, sheerly absurd. It will be noticed that -I say theorizing, not hypothesis-framing; for though he -speaks of hypotheses, he in reality is describing theories. -The word hypothesis is too frequently used in this incorrect -sense—perhaps so frequently that we may almost prefer -sanctioning the use to substituting the correct word. But -the fact really is, that many, even among scientific writers,<span class="pagenum"><a id="Page_108">108</a></span> -when they hear the word hypothesis, think immediately of -Newton’s famous “hypotheses non fingo,” a dictum relating -to real hypotheses, not to theories. It would, in fact, be -absurd to suppose that Newton, who had advanced, advocated, -and eventually established, the noblest scientific -theory the world has known, would ever have expressed an -objection to theorizing, as he is commonly understood to -have done by those who interpret his “hypotheses non -fingo” in the sense which finds favour with M. Cornu. But -apart from this, Newton definitely indicates what he means -by hypotheses. “I frame no hypotheses,” he says, “<em>for -whatever is not deduced from phenomena is to be called an -hypothesis</em>.” M. Cornu, it will be seen, rejects the idea of -deducing from phenomena what he calls an hypothesis, but -what would not be an hypothesis according to Newton’s -definition: “Malgré tout ce qu’il y aurait de séduisant et de -grandiose à tirer de ce fait des inductions, etc., je m’abstiendrai -de tout commentaire et de toute hypothèse à ce sujet.” -It is not thus that observed scientific facts are to be made -fruitful, nor thus that the points to which closer attention -must be given are to be ascertained.</p> - -<p>Since the preceding paragraph was written, my attention -has been attracted to the words of another observer more -experienced than M. Cornu, who has not only expressed the -same opinion which I entertain respecting M. Cornu’s ill-advised -remark, but has illustrated in a very practical way, -and in this very case, how science gains from commentary -and theory upon observed facts. Herr Vögel considers “that -the fear that an hypothesis” (he, also, means a theory here) -“might do harm to science is only justifiable in very rare -cases: in most cases it will further science. In the first -place, it draws the attention of the observer to things -which but for the hypothesis might have been neglected. -Of course if the observer is so strongly influenced that in -favour of an hypothesis he sees things which do not exist—and -this may happen sometimes—science may for a while -be arrested in its progress, but in that case the observer is<span class="pagenum"><a id="Page_109">109</a></span> -far more to blame than the author of the hypothesis. On -the other hand, it is very possible that an observer may, -involuntarily, arrest the progress of science, even without -originating an hypothesis, by pronouncing and publishing -sentences which have a tendency to diminish the general -interest in a question, and which do not place its high significance -in the proper light.” (This is very neatly put.) He -is “almost inclined to think that such an effect might follow -from the reading of M. Cornu’s remark, and that nowhere -better than in the present case, where in short periods -colossal changes showed themselves occurring upon a -heavenly body, might the necessary data be obtained for -drawing useful conclusions, and tests be applied to those -hypotheses which have been ventured with regard to the -condition of heavenly bodies.” It was, as we shall presently -see, in thus collecting data and applying tests, that Vögel -practically illustrated the justice of his views.</p> - -<p>The star which shone out in the Northern Crown in -May, 1866, would seem to have grown to its full brightness -very quickly. It is not necessary that I should here consider -the history of the star’s discovery; but I think all who -have examined that history agree in considering that whereas -on the evening of May 12, 1866, a new star was shining in -the Northern Crown with second-magnitude brightness, none -had been visible in the same spot with brightness above -that of a fifth-magnitude star twenty-four hours earlier. On -ascertaining, however, the place of the new star, astronomers -found that there had been recorded in Argelander’s -charts and catalogue a star of between the ninth and tenth -magnitude in this spot. The star declined very rapidly in -brightness. On May 13th it appeared of the third magnitude; -on May 16th it had sunk to the fourth magnitude; -on the 17th to the fifth; on the 19th to the seventh; and -by the end of the month it shone only as a telescopic star -of the ninth magnitude. It is now certainly not above the -tenth magnitude.</p> - -<p>Examined with the spectroscope, this star was found to<span class="pagenum"><a id="Page_110">110</a></span> -be in an abnormal condition. It gave the rainbow-tinted -streak crossed by dark lines, which is usually given by stars -(with minor variations, which enable astronomers to classify -the stars into several distinct orders). But superposed upon -this spectrum, or perhaps we should rather say shining -through this spectrum, were seen four brilliant lines, two -of which certainly belonged to glowing hydrogen. These -lines were so bright as to show that the greater part of the -light of the star at the time came from the glowing gas or -gases giving these lines. It appeared, however, that the -rainbow-tinted spectrum on which these lines were seen was -considerably brighter than it would otherwise have been, in -consequence of the accession of heat indicated by and -probably derived from the glowing hydrogen.</p> - -<p>Unfortunately, we have not accordant accounts of the -changes which the spectrum of this star underwent as the -star faded out of view. Wolf and Rayet, of the Paris -Observatory, assert that when there remained scarcely any -trace of the continuous spectrum, the four bright lines were -still quite brilliant. But Huggins affirms that this was not -the case in his observations; he was “able to see the continuous -spectrum when the bright lines could be scarcely -distinguished.” As the bright lines certainly faded out of -view eventually, we may reasonably assume that the French -observers were prevented by the brightness of the lines from -recognizing the continuous spectrum at that particular stage -of the diminution of the star’s light when the continuous -spectrum had faded considerably but the hydrogen lines -little. Later, the continuous spectrum ceased to diminish in -brightness, while the hydrogen lines rapidly faded. Thereafter -the continuous spectrum could be discerned, and with greater -and greater distinctness as the hydrogen lines faded out.</p> - -<p>Now, in considering the meaning of the observed changes -in the so-called “new star,” we have two general theories to -consider.</p> - -<p>One of these theories is that to which Dr. Huggins -would seem to have inclined, though he did not definitely<span class="pagenum"><a id="Page_111">111</a></span> -adopt it—the theory, namely, that in consequence of some -internal convulsion enormous quantities of hydrogen and -other gases were evolved, which in combining with some -other elements ignited on the surface of the star, and thus -enveloped the whole body suddenly in a sheet of flame.</p> - -<p>“The ignited hydrogen gas in burning produced the -light corresponding to the two bright bands in the red and -green; the remaining bright lines were not, however, coincident -with those of oxygen, as might have been expected. -According to this theory, the burning hydrogen must have -greatly increased the heat of the solid matter of the photosphere -and brought it into a state of more intense incandescence -and luminosity, which may explain how the formerly -faint star could so suddenly assume such remarkable brilliance; -the liberated hydrogen became exhausted, the -flame gradually abated, and with the consequent cooling the -photosphere became less vivid, and the star returned to its -original condition.”</p> - -<p>According to the other theory, advanced by Meyer and -Klein, the blazing forth of this new star may have been -occasioned by the violent precipitation of some great mass, -perhaps a planet, upon a fixed star, “by which the -momentum of the falling mass would be changed into -molecular motion,” and result in the emission of light and -heat.</p> - -<p>“It might even be supposed that the new star, through -its rapid motion, may have come in contact with one of the -nebulæ which traverse in great numbers the realms of space -in every direction, and which from their gaseous condition -must possess a high temperature; such a collision would -necessarily set the star in a blaze, and occasion the most -vehement ignition of its hydrogen.”</p> - -<p>If we regard these two theories in their more general -aspect, considering one as the theory that the origin of disturbance -was within the star, and the other as the theory -that the origin of disturbance was outside the star, they -seem to include all possible interpretations of the observed<span class="pagenum"><a id="Page_112">112</a></span> -phenomena. But, as actually advanced, neither seems -satisfactory. The sudden pouring forth of hydrogen from -the interior, in quantities sufficient to explain the outburst, -seems altogether improbable. On the other hand, as I -have pointed out elsewhere, there are reasons for rejecting -the theory that the cause of the heat which suddenly affected -this star was either the downfall of a planet on the star or -the collision of the star with a star-cloudlet or nebula, -traversing space in one direction, while the star rushed -onwards in another.</p> - -<p>A planet could not very well come into final conflict -with its sun at one fell swoop. It would gradually draw -nearer and nearer, not by the narrowing of its path, but by -the change of the path’s shape. The path would, in fact, -become more and more eccentric; until at length, at its -point of nearest approach, the planet would graze its -primary, exciting an intense heat where it struck, but -escaping actual destruction that time. The planet would -make another circuit, and again graze the sun, at or near -the same part of the planet’s path. For several circuits this -would continue, the grazes not becoming more and more -effective each time, but rather less. The interval between -them, however, would grow continually less and less; at last -the time would come when the planet’s path would be -reduced to the circular form, its globe touching the sun’s -all the way round, and then the planet would very quickly -be reduced to vapour and partly burned up, its substance -being absorbed by its sun. But all successive grazes would -be indicated to us by accessions of lustre, the period between -each seeming outburst being only a few months at first, and -gradually becoming less and less (during a long course of -years, perhaps even of centuries) until the planet was -finally destroyed. Nothing of this sort has happened in the -case of any so-called new star. As for the rush of a star -through a nebulous mass, that is a theory which would -scarcely be entertained by any one acquainted with the -enormous distances separating the gaseous star-clouds<span class="pagenum"><a id="Page_113">113</a></span> -properly called nebulæ. There may be small clouds of -the same sort scattered much more freely through space; -but we have not a particle of evidence that this is actually -the case. All we certainly <em>know</em> about star-cloudlets suggests -that the distances separating them from each other are -comparable with those which separate star from star, in -which case the idea of a star coming into collision with a -star-cloudlet, and still more the idea of this occurring several -times in a century, is wild in the extreme.</p> - -<p>But while thus advancing objections, which seem to me -irrefragable, against the theory that either a planet or a -nebula (still less another small star) had come into collision -with the orb in Corona which shone out so splendidly for a -while, I advanced another view which seemed to me then -and seems now to correspond well with phenomena, and to -render the theory of action from without on the whole -preferable to the theory of outburst from within. I suggested -that, far more probably, an enormous flight of large -meteoric masses travelling around the star had come into -partial collision with it in the same way that the flight of -November meteors comes into collision with our earth -thrice in each century, and that other meteoric flights may -occasionally come into collision with our sun, producing the -disturbances which occasion the sun-spots. As I pointed -out, in conceiving this we are imagining nothing new. A -meteoric flight capable of producing the suggested effects -would differ only in kind from meteoric flights which are -known to circle around our own sun. The meteors which -produce the November displays of falling stars follow in the -track of a comet barely visible to the naked eye.</p> - -<p>“May we not reasonably assume that those glorious -comets which have not only been visible but conspicuous, -shining even in the day-time, and brandishing around tails, -which like that of the ‘wonder in heaven, the great dragon,’ -seemed to ‘draw the third part of the stars of heaven,’ are -followed by much denser flights of much more massive -meteors? Some of these giant comets have paths which<span class="pagenum"><a id="Page_114">114</a></span> -carry them very close to our sun. Newton’s comet, with its -tail a hundred millions of miles in length, all but grazed the -sun’s globe. The comet of 1843, whose tail, says Sir John -Herschel, ‘stretched half-way across the sky,’ must actually -have grazed the sun, though but lightly, for its nucleus was -within 80,000 miles of his surface, and its head was more -than 160,000 miles in diameter. And these are only two -among the few comets whose paths are known. At any -time we might be visited by a comet mightier than either, -travelling in an orbit intersecting the sun’s surface, followed -by flights of meteoric masses enormous in size and many in -number, which, falling on the sun’s globe with enormous -velocity corresponding to their vast orbital range and their -near approach to the sun—a velocity of some 360 miles per -second—would, beyond all doubt, excite his whole frame, -and especially his surface regions, to a degree of heat far -exceeding what he now emits.”</p> - -<p>This theory corresponds far better also with observed -facts than the theory of Meyer and Klein, in other respects -than simply in antecedent probability. It can easily be -shown that if a planet fell upon a sun in such sort as to -become part of his mass, or if a nebula in a state of intense -heat excited the whole frame of a star to a similar degree -of heat, the effects would be of longer duration than the -observed accession of heat and light in the case of all the -so-called “new stars.” It has been calculated by Mr. Croll -(the well-known mathematician to whom we owe the most -complete investigations yet made into the effect of the -varying eccentricity of the earth’s orbit on the climate of the -earth) that if two suns, each equal in mass to one-half of -our sun, came into collision with a velocity of 476 miles per -second, light and heat would be produced which would -cover the present rate of the sun’s radiation for fifty million -years. Now although it certainly does not follow from this -that such a collision would result in the steady emission of -so much light and heat as our sun gives out, for a period of -fifty million years, but is, on the contrary, certain that there<span class="pagenum"><a id="Page_115">115</a></span> -would be a far greater emission at first and a far smaller -emission afterwards, yet it manifestly must be admitted that -such a collision could not possibly produce so short-lived an -effect as we see in the case of every one of the so-called new -stars. The diminution in the emission of light and heat -from the maximum to one-half the maximum would not -occupy fifty millions of years, or perhaps even five million or -five hundred thousand years; but it would certainly require -thousands of years; whereas we have seen that the new stars -in the Crown and in the Swan have lost not one-half but -ninety-nine hundredths of their maximum lustre in a few -months.</p> - -<p>This has been urged as an objection even to the term -star as applied to these suddenly appearing orbs. But the -objection is not valid; because there is no reason whatever -for supposing that even our own sun might not be excited -by the downfall of meteoric or cometic matter upon it to -a sudden and short-lasting intensity of splendour and of -heat. Mr. Lockyer remarks that, if any star, properly so -called, were to become a “a world on fire,” or “burst into -flames,” or, in less poetical language, were to be driven -either into a condition of incandescence absolutely, or to -have its incandescence increased, there can be little doubt -that thousands or millions of years would be necessary for -the reduction of its light to its original intensity. This -must, however, have been written in forgetfulness of some -facts which have been ascertained respecting our sun, and -which indicate pretty clearly that the sun’s surface might be -roused to a temporary intensity of splendour and heat without -any corresponding increase in the internal heat, or in -the activity of the causes, whatever they may be, to which -the sun’s <em>steady</em> emissions of light and heat are due.</p> - -<p>For instance, most of my readers are doubtless familiar -with the account (an oft-told tale, at any rate) of the sudden -increase in the splendour of a small portion of the sun’s -surface on September 1, 1859, observed by two astronomers -independently. The appearances described corresponded<span class="pagenum"><a id="Page_116">116</a></span> -exactly with what we should expect if two large meteoric -masses travelling side by side had rushed, with a velocity -originally amounting to two or three hundred miles per -second, through the portions of the solar atmosphere lying -just above, at, and just below the visible photosphere. The -actual rate of motion was measured at 120 miles per second -as the minimum, but may, if the direction of motion was -considerably inclined to the line of sight, have amounted -to more than 200 miles per second. The effect was such, -that the parts of the sun thus suddenly excited to an -increased emission of light and heat appeared like bright -stars upon the background of the glowing photosphere -itself. One of the observers, Carrington, supposed for a -moment that the dark glass screen used to protect the eye -had broken. The increase of splendour was exceedingly -limited in area, and lasted only for a few minutes—fortunately -for the inhabitants of earth. As it was, the whole -frame of the earth sympathized with the sun. Vivid auroras -were seen, not only in both hemispheres, but in latitudes -where auroras are seldom seen. They were accompanied -by unusually great electro-magnetic disturbances.</p> - -<p>“In many places,” says Sir J. Herschel, “the telegraph -wires struck work. At Washington and Philadelphia, the -electric signalmen received severe electric shocks. At a -station in Norway, the telegraphic apparatus was set fire to, -and at Boston, in North America, a flame of fire followed -the pen of Bain’s electric telegraph, which writes down the -message upon chemically prepared paper.”</p> - -<p>We see, then, that most certainly the sun can be locally -excited to increased emission of light and heat, which nevertheless -may last but for a very short time; and we have -good reason for believing that the actual cause of the sudden -change in his condition was the downfall of meteoric matter -upon a portion of his surface. We may well believe that, -whatever the cause may have been, it was one which might -in the case of other suns, or even in our sun’s own case, -affect a much larger portion of the photosphere. If this happened<span class="pagenum"><a id="Page_117">117</a></span> -there would be just such an accession of splendour as -we recognize in the case of the new stars. And as the small -local accession of brilliancy lasted only a few minutes, we can -well believe that an increase of surface brilliancy affecting a -much larger portion of the photosphere, or even the entire -photosphere, might last but for a few days or weeks.</p> - -<p>All that can be said in the way of negative evidence, so -far as our own sun is concerned, is that we have no reason -for believing that our sun has, at any time within many -thousands of years, been excited to emit even for a few hours -a much greater amount of light and heat than usual; so that -it has afforded no direct evidence in favour of the belief that -other suns may be roused to many times their normal splendour, -and yet very quickly resume that usual lustre. But we -know that our sun, whether because of his situation in space, -or of his position in time (that is, the stage of solar development -to which he has at present attained), belongs to the -class of stars which shine with steady lustre. He does not -vary like Betelgeux, for example, which is not only a sun like -him as to general character, but notably a larger and more -massive orb. Still less is he like Mira, the Wonderful Star; -or like that more wonderful variable star, Eta Argûs, which -at one time shines with a lustre nearly equalling that of the -bright Sirius, and anon fades away almost into utter invisibility. -He <em>is</em> a variable sun, for we cannot suppose that the -waxing and waning of the sun-spot period leaves his lustre, -as a whole, altogether unaffected. But his variation is so -slight that, with all ordinary methods of photometric measurement -by observers stationed on worlds which circle around -other suns, it must be absolutely undiscernible. We do not, -however, reject Betelgeux, or Mira, or even Eta Argûs, -from among stars because they vary in lustre. We recognize -the fact that, as in glory, so in condition and in changes of -condition, one star differeth from another.</p> - -<p>Doubtless there are excellent reasons for rejecting the -theory that a massive body like a planet, or a nebulous mass -like those which are found among the star-depths (the least<span class="pagenum"><a id="Page_118">118</a></span> -of which would exceed many times in volume a sphere filling -the entire space of the orbit of Neptune), fell on some remote -sun in the Northern Crown. But there are no sufficient -reasons for rejecting or even doubting the theory that a comet, -bearing in its train a flight of many millions of meteoric masses, -falling directly upon such a sun, might cause it to shine with -many times its ordinary lustre, but only for a short time, a few -months or weeks, or a few days, or even hours. In the article -entitled “Suns in Flames,” in my “Myths and Marvels of -Astronomy,” before the startling evidence recently obtained -from the star in Cygnus had been thought of, I thus indicated -the probable effects of such an event:—“When the earth has -passed through the richer portions (not the actual nuclei be it -remembered) of meteor systems, the meteors visible from even -a single station have been counted by tens of thousands, and -it has been computed that millions must have fallen upon -the whole earth. These were meteors following in the trains -of very small comets. If a very large comet followed by no -denser a flight of meteors, but each meteoric mass much -larger, fell directly upon the sun, it would not be the outskirts -but the nucleus of the meteoric train which would -impinge upon him. They would number thousands of -millions. The velocity of downfall of each mass would be -more than 360 miles per second. And they would continue -to pour in upon him for several days in succession, millions -falling every hour. It seems not improbable that under this -tremendous and long-continued meteoric hail, his whole surface -would be caused to glow as intensely as that small part -whose brilliancy was so surprising in the observation made -by Carrington and Hodgson. In that case our sun, seen -from some remote star whence ordinarily he is invisible, -would shine out as a new sun for a few days, while all things -living, on our earth and whatever other members of the solar -system are the abodes of life, would inevitably be destroyed.”</p> - -<p>There are, indeed, reasons for believing, not only, as I -have already indicated, that the outburst in the sun was -caused by the downfall of meteoric masses, but that those<span class="pagenum"><a id="Page_119">119</a></span> -masses were following in the train of a known comet, precisely -as the November meteors follow in the train of -Tempel’s comet (II., 1866). For we know that November -meteoric displays have been witnessed for five or six years -after the passage of Tempel’s comet, in its thirty-three year -orbit, while the August meteoric displays have been witnessed -fully one hundred and twenty years after the passage of their -comet (II., 1862).<a id="FNanchor_15" href="#Footnote_15" class="fnanchor">15</a> Now only sixteen years before the solar -outburst witnessed by Carrington and Hodgson, a magnificent -comet had passed even closer to the sun than either Tempel’s -comet or the second comet of 1862 approached the earth’s -orbit. That was the famous comet of the year 1843. Many -of us remember that wonderful object. I was but a child -myself when it appeared, but I can well remember its -amazing tail, which in March, 1843, stretched half-way across -the sky.</p> - -<p>“Of all the comets on record,” says Sir J. Herschel, -“that approached nearest the sun; indeed, it was at first -supposed that it had actually grazed the sun’s surface, but it -proved to have just missed by an interval of not more than -80,000 miles—about a third of the distance of the moon -from the earth, which (in such a matter) is a very close shave -indeed to get clear off.”</p> - -<p>We can well believe that the two meteors which produced -the remarkable outburst of 1859 may have been stragglers -from the main body following after that glorious comet. I -do not insist upon the connection. In fact, I rather incline -to the belief that the disturbance in 1859, occurring as it did -about the time of maximum sun-spot frequency, was caused -by meteors following in the train of some as yet undiscovered -comet, circuiting the sun in about eleven years, the spots<span class="pagenum"><a id="Page_120">120</a></span> -themselves being, I believe, due in the main to meteoric -downfalls. There is greater reason for believing that the -great sun-spot which appeared in June, 1843, was caused by -the comet which three months before had grazed the sun’s -surface. As Professor Kirkwood, of Bloomington, Indiana, -justly remarks, had this comet approached a little nearer, the -resistance of the solar atmosphere would probably have -brought the comet’s entire mass to the solar surface. Even -at its actual distance, it must have produced considerable -atmospheric disturbance. But the recent discovery that a -number of comets are associated with meteoric matter travelling -in nearly the same orbits, suggests the inquiry whether -an enormous meteorite following in the comet’s train, and -having a somewhat less perihelion distance, may not have been -precipitated upon the sun, thus producing the great disturbance -observed so shortly after the comet’s perihelion passage.</p> - -<p>Let us consider now the evidence obtained from the star -in Cygnus, noting especially in what points it resembles, and -in what points it differs from, the evidence afforded by the -star in the Crown.</p> - -<p>The new star was first seen by Professor Schmidt at a -quarter to six on the evening of November 24. It was then -shining as a star of the third magnitude, in the constellation -of the Swan, not very far from the famous but faint star 61 -Cygni—which first of all the stars in the northern heavens -had its distance determined by astronomers. The three -previous nights had unfortunately been dark; but Schmidt -is certain that on November 20 the star was not visible. At -midnight, November 24, its light was very yellow, and it was -somewhat brighter than the well-known star Eta Pegasi, -which marks the forearm of the Flying Horse. Schmidt -sent news of the discovery to Leverrier, at Paris; but neither -he nor Leverrier telegraphed the news, as they should have -done, to Greenwich, Berlin, or the United States. Many -precious opportunities for observing the spectrum of the -new-comer at the time of its greatest brilliancy were thus -lost.</p> - -<p><span class="pagenum"><a id="Page_121">121</a></span> -The observers at Paris did their best to observe the -spectrum of the star and the all-important changes in the -spectrum. But they had unfavourable weather. It was not -till December 2 that the star was observed at Paris, by which -time the colour, which had been very yellow on November -24, had become “greenish, almost blue.” The star had also -then sunk from the third to far below the fourth magnitude. -It is seldom that science has to regret a more important loss -of opportunity than this. What we want specially to know -is the nature of the spectrum given by this star when its -light was yellow; and this we can now never know. Nor -are the outbursts of new stars so common that we may -quickly expect another similar opportunity, even if any -number of other new stars should present the same series of -phenomena as the star in Cygnus.</p> - -<p>On December 2, the spectrum, as observed by M. -Cornu, consisted almost entirely of bright lines. On December -5, he determined the position of these lines, though -clouds still greatly interfered with his labours. He found -three bright lines of hydrogen, the strong double sodium -line in the orange-yellow, the triple magnesium line in the -yellow-green, and two other lines—one of which seemed to -agree exactly in position with a bright line belonging to the -solar corona. All these lines were shining upon the rainbow-tinted -background of the spectrum, which was relatively faint. -He drew the conclusion that in chemical constitution the -atmosphere of the new star was constituted exactly like the -solar sierra.</p> - -<p>Herr Vögel’s observations commenced on December 5, -and were continued at intervals until March 10, when the -star had sunk to below the eighth magnitude.</p> - -<p>Vögel’s earlier observations agreed well with Cornu’s. -He remarks, however, that Cornu’s opinion as to the exact -resemblance of the chemical constitution of the star’s atmosphere -with that of the sierra is not just, for both Cornu -and himself noticed one line which did not correspond -with any line belonging to the solar sierra; and this line<span class="pagenum"><a id="Page_122">122</a></span> -eventually became the brightest line of the whole spectrum. -Comparing his own observations with those of Cornu, -Vögel points out that they agree perfectly with regard to -the presence of the three hydrogen lines, and that of the -brightest line of the air spectrum (belonging to nitrogen),—which -is the principal line of the spectrum of nebulæ. -This is the line which has no analogue in the spectrum -of the sierra.</p> - -<p>We have also observations by F. Secchi, at Rome, Mr. -Copeland, at Dunecht, and Mr. Backhouse, of Sunderland, -all agreeing in the main with the observations made by -Vögel and Cornu. In particular, Mr. Backhouse observed, -as Vögel had done, that whereas in December the greenish-blue -line of hydrogen, F, was brighter than the nitrogen -line (also in the green-blue, but nearer the red end than -F), on January 6 the nitrogen line was the brightest of -all the lines in the spectrum of the new star.</p> - -<p>Vögel, commenting on the results of his observations up -to March 10, makes the following interesting remarks (I -quote, with slight verbal alterations, from a paraphrase in a -weekly scientific journal):—“A stellar spectrum with <em>bright</em> -lines is always a highly interesting phenomenon for any -one acquainted with stellar spectrum analysis, and well -worthy of deep consideration. Although in the chromosphere -(sierra) of our sun, near the limb, we see numerous -bright lines, yet only dark lines appear in the spectrum -whenever we produce a small star-like image of the sun, -and examine it through the spectroscope. It is generally -believed that the bright lines in some few star-spectra -result from gases which break forth from the interior of -the luminous body, the temperature of which is higher than -that of the surface of the body—that is, the phenomenon -is the same sometimes observed in the spectra of solar -spots, where incandescent hydrogen rushing out of the -hot interior becomes visible above the cooler spots through -the hydrogen lines turning bright. But this is not the only -possible explanation. We may also suppose that the atmosphere<span class="pagenum"><a id="Page_123">123</a></span> -of a star, consisting of incandescent gases, as is -the case with our own sun, is on the whole cooler than the -nucleus, but with regard to the latter is extremely large. -I cannot well imagine how the phenomenon can last for -any long period of time if the former hypothesis be correct. -The gas breaking forth from the hot interior of the body -will impart a portion of its heat to the surface of the body, -and thus raise the temperature of the latter; consequently, -the difference of temperature between the incandescent -gas and the surface of the body will soon be insufficient -to produce bright lines; and these will disappear from -the spectrum. This view applies perfectly to stars which -suddenly appear and soon disappear again, or at least -increase considerably in intensity—that is, it applies perfectly -to so-called new stars in the spectra of which bright -lines are apparent, <em>if</em> the hypothesis presently to be -mentioned is admitted for their explanation. For a more -stable state of things the second hypothesis seems to be -far better adapted. Stars like Beta Lyræ, Gamma Cassiopeiæ, -and others, which show the hydrogen lines and the -sierra D line bright on a continuous spectrum, with only -slight changes of intensity, possess, according to this theory, -atmospheres very large relatively to their own volume—the -atmospheres consisting of hydrogen and that unknown -element which produces the D line.<a id="FNanchor_16" href="#Footnote_16" class="fnanchor">16</a> With regard to the -new star, Zöllner, long before the progress lately made in -stellar physics by means of spectrum analysis, deduced from -Tycho’s observations of the star called after him, that on -the surface of a star, through the constant emission of heat, -the products of cooling, which in the case of our sun we call -sun-spots, accumulate: so that finally the whole surface of -the body is covered with a colder stratum, which gives<span class="pagenum"><a id="Page_124">124</a></span> -much less light or none at all. Through a sudden and -violent tearing up of this stratum, the interior incandescent -materials which it encloses must naturally break forth, and -must in consequence, according to the extent of their eruption, -cause larger or smaller patches of the dark envelope -of the body to become luminous again. To a distant observer -such an eruption from the hot and still incandescent -interior of a heavenly body must appear as the sudden -flashing-up of a new star. That this evolution of light -may under certain conditions be an extremely powerful -one, could be explained by the circumstance that all the -chemical compounds which, under the influence of a lower -temperature, had already formed upon the surface, are again -decomposed through the sudden eruption of these hot -materials; and that this decomposition, as in the case of -terrestrial substances, takes place under evolution of light -and heat. Thus the bright flashing-up is not only ascribed -to the parts of the surface which through the eruption of the -incandescent matter have again become luminous, but also -to a simultaneous process of combustion, which is initiated -through the colder compounds coming into contact with the -incandescent matter.”</p> - -<p>Vögel considers that Zöllner’s hypothesis has been confirmed -in its essential points by the application of spectrum -analysis to the stars. We can recognize from the spectrum -different stages in the process of cooling, and in some of the -fainter stars we perceive indeed that chemical compounds -have already formed, and still exist. As to new stars, again, -says Vögel, Zöllner’s theory seems in nowise contradicted -“by the spectral observations made on the two new stars of -1866 and 1876. The bright continuous spectrum, and the -bright lines only slightly exceeding it at first” (a description, -however, applying correctly only to the star of 1876), “could -not be well explained if we only suppose a violent eruption -from the interior, which again rendered the surface wholly -or partially luminous; but are easily explained if we suppose -that the quantity of light is considerably augmented through<span class="pagenum"><a id="Page_125">125</a></span> -a simultaneous process of combustion. If this process is of -short duration, then the continuous spectrum, as was the -case with the new star of 1876, will very quickly decrease in -intensity down to a certain limit, while the bright lines in the -spectrum, which result from the incandescent gases that -have emanated in enormous quantities from the interior, will -continue for some time.”</p> - -<p>It thus appears that Herr Vögel regarded the observations -which had been made on this remarkable star up to -March 10 as indicating that first there had been an outburst -of glowing gaseous matter from the interior, producing the -part of the light which gave the bright lines indicative of -gaseity, and that then there had followed, as a consequence, -the combustion of a portion of the solid and relatively cool -crust, causing the continuous part of the spectrum. We -may compare what had taken place, on this hypothesis, with -the outburst of intensely hot gases from the interior of a -volcanic crater, and the incandescence of the lips of the -crater in consequence of the intense heat of the out-rushing -gases. Any one viewing such a crater from a distance, with -a spectroscope, would see the bright lines belonging to the -out-rushing gases superposed upon the continuous spectrum -due to the crater’s burning lips. Vögel further supposes -that the burning parts of the star soon cooled, the majority -of the remaining light (or at any rate the part of the remaining -light spectroscopically most effective) being that -which came from the glowing gases which had emanated in -vast quantities from the star’s interior.</p> - -<p>“The observations of the spectrum show, beyond doubt,” -he says, “that the decrease in the light of the star corresponds -with the cooling of its surface. The violet and blue -parts decreased more rapidly in intensity than the other -parts; and the absorption-bands which crossed the spectrum -have gradually become darker and darker.”</p> - -<p>The reasoning, however, if not altogether unsatisfactory, -is by no means so conclusive as Herr Vögel appears to think. -It is not clear how the incandescent portion of the surface<span class="pagenum"><a id="Page_126">126</a></span> -could possibly cool in any great degree while enormous -quantities of gas more intensely heated (by the hypothesis) -remained around the star. The more rapid decrease in the -violet and blue parts of the spectrum than in the red and -orange is explicable as an effect of absorption, at least as -readily as by the hypothesis that burning solid or liquid -matter had cooled. Vögel himself could only regard the -other bands which crossed the spectrum as absorption-bands. -And the absorption of light from the continuous spectrum -in these parts (that is, not where the bright lines belonging -to the gaseous matter lay) could not possibly result from -absorption produced by those gases. If other gases were -in question, gases which, by cooling with the cooling surface, -had become capable of thus absorbing light from special -parts of the spectrum, how is it that before, when these -gases were presumably intensely heated, they did not indicate -their presence by bright bands? Bright bands, indeed, -were seen, which eventually faded out of view, but -these bright bands did not occupy the position where, later -on, absorption-bands appeared.</p> - -<p>The natural explanation of what had thus far been observed -is different from that advanced by Vögel, though we -must not assume that because it is the natural, it is necessarily -the true explanation. It is this—that the source of that -part of the star’s light which gave the bright-line spectrum, -or the spectrum indicative of gaseity, belongs to the normal -condition of the star, and not to gases poured forth, in consequence -of some abnormal state of things, from the sun’s -interior. We should infer naturally, though again I say not -<em>therefore</em> correctly, that if a star spectroscope had been -directed upon the place occupied by the new star before -it began to shine with unusual splendour, the bright-line -spectrum would have been observed. Some exceptional -cause would then seem to have aroused the entire surface -of the star to shine with a more intense brightness, the -matter thus (presumably) more intensely heated being such -as would give out the combined continuous and bright-line<span class="pagenum"><a id="Page_127">127</a></span> -spectrum, including the bright lines which, instead of fading -out, shone with at least relatively superior brightness as the -star faded from view. The theory that, on the contrary, -the matter giving these more persistent lines was that whose -emission caused the star’s increase of lustre, seems at least -not proven, and I would go so far as to say that it accords -ill with the evidence.</p> - -<p>The question, be it noted, is simply whether we should -regard the kind of light which lasts longest in this star as it -fades out of view as more probably belonging to the star’s -abnormal brightness or to its normal luminosity. It seems -to me there can be little doubt that the persistence of this -part of the star’s light points to the latter rather than to the -former view.</p> - -<p>Let it also be noticed that the changes which had been -observed thus far were altogether unlike those which had -been observed in the case of the star in the Northern Crown, -and therefore cannot justly be regarded as pointing to the -same explanation. As the star in the Crown faded from -view, the bright lines indicative of glowing hydrogen died -out, and only the ordinary stellar spectrum remained. In the -case of the star in the Swan, the part of the spectrum corresponding -to stellar light faded gradually from view, and bright -lines only were left, at least as conspicuous parts of the star’s -spectrum. So that whereas one orb seemed to have faded -into a faint star, the other seemed fading out into a nebula—not -merely passing into such a condition as to shine with -light indicative of gaseity, but actually so changing as to -shine with light of the very tints (or, more strictly, of the -very wave-lengths) observed in all the gaseous nebulæ.</p> - -<p>The strange eventful history of the new star in Cygnus -did not end here, however. We may even say, indeed, -that it has not ended yet. But another chapter can already -be written.</p> - -<p>Vögel ceased from observing the star in March, precisely -when observation seemed to promise the most interesting -results. At most other observatories, also, no observations<span class="pagenum"><a id="Page_128">128</a></span> -were made for about half a year. At the Dunecht Observatory<a id="FNanchor_17" href="#Footnote_17" class="fnanchor">17</a> -pressure of work relating to Mars interfered with the -prosecution of those observations which had been commenced -early in the year. But on September 3, Lord -Lindsay’s 15-inch reflector was directed upon the star. A -star was still shining where the new star’s yellow lustre had -been displayed in November, 1876; but now the star shone -with a faint blue colour. Under spectroscopic examination, -however, the light from this seeming blue star was -found not to be starlight, properly speaking, at all. It -formed no rainbow-tinted spectrum, but gave light of only -a single colour. The single line now seen was that which -at the time of Vögel’s latest observation had become the -strongest of the bright lines of the originally complex -spectrum of the so-called new star. It is the brightest of -the lines given by the gaseous nebulæ. In fact, if nothing -had been known about this body before the spectroscopic -observation of September 3 was made, the inference from -the spectrum given by the blue star would undoubtedly have -been that the object is in reality a small nebula of the -planetary sort, very similar to that one close by the pole of -the ecliptic, which gave Huggins the first evidence of the -gaseity of nebulæ, but very much smaller. I would specially -direct the reader’s attention, in fact, to Huggins’s account -of his observation of that planetary nebula in the Dragon. -“On August 19, 1864,” he says, “I directed the telescope -armed with the spectrum apparatus to this nebula. At first -I suspected some derangement of the instrument had taken -place, for no spectrum was seen, but only” a single line of -light. “I then found that the light of this nebula, unlike -any other extra-terrestrial light which had yet been subjected -by me to prismatic analysis, was not composed of -light of different refrangibilities, and therefore could not -form a spectrum. A great part of the light from this nebula<span class="pagenum"><a id="Page_129">129</a></span> -is monochromatic, and after passing through the prisms -remains concentrated in a bright line.” A more careful -examination showed that not far from the bright line was -a much fainter line; and beyond this, again, a third exceedingly -faint line was seen. The brightest of the three -lines was a line of nitrogen corresponding in position with -the brightest of the lines in the spectrum of our own air. -The faintest corresponded in position with a line of hydrogen. -The other has not yet been associated with a known line -of any element. Besides the faint lines, Dr. Huggins perceived -an exceedingly faint continuous spectrum on both -sides of the group of bright lines; he suspected, however, -that this faint spectrum was not continuous, but crossed by -dark spaces. Later observations on other nebulæ induced -him to regard this faint continuous spectrum as due to the -solid or liquid matter of the nucleus, and as quite distinct -from the bright lines into which nearly the whole of the -light from the nebula is concentrated. The fainter parts of -the spectrum of the gaseous nebulæ, in fact, correspond to -those parts of the spectrum of the “new star” in Cygnus -which last remained visible, before the light assumed its -present monochromatic colour.</p> - -<p>Now let us consider the significance of the evidence -afforded by this discovery—not perhaps hoping at once -to perceive the full meaning of the discovery, but endeavouring -to advance as far as we safely can in the direction -in which it seems to point.</p> - -<p>We have, then, these broad facts: where no star had -been known, an object has for a while shone with stellar -lustre, in this sense, that its light gave a rainbow-tinted -spectrum not unlike that which is given by a certain -order of stars; this object has gradually parted with its -new lustre, and in so doing the character of its spectrum -has slowly altered, the continuous portion becoming fainter, -and the chief lustre of the bright-line portion shifting from -the hydrogen lines to a line which, there is every reason to -believe, is absolutely identical with the nebula nitrogen line:<span class="pagenum"><a id="Page_130">130</a></span> -and lastly, the object has ceased to give any perceptible -light, other than that belonging to this nitrogen line.</p> - -<p>Now it cannot, I think, be doubted that, accompanying -the loss of lustre in this orb, there has been a corresponding -loss of heat. The theory that all the solid and liquid -materials of the orb have been vaporized by intense heat, -and that this vaporization has caused the loss of the star’s -light (as a lime-light might die out with the consumption -of the lime, though the flame remained as hot as ever), -is opposed by many considerations. It seems sufficient to -mention this, that if a mass of solid matter, like a dead -sun or planet, were exposed to an intense heat, first raising -it to incandescence, and eventually altogether vaporizing -its materials, although quite possibly the time of its intensest -lustre might precede the completion of the vaporization, -yet certainly so soon as the vaporization was complete, -the spectrum of the newly vaporized mass would show -multitudinous bright lines corresponding to the variety of -material existing in the body. No known fact of spectroscopic -analysis lends countenance to the belief that a -solid or liquid mass, vaporized by intense heat, would shine -thenceforth with monochromatic light.</p> - -<p>Again, I think we are definitely compelled to abandon -Vögel’s explanation of the phenomena by Zöllner’s theory. -The reasons which I have urged above are not only -strengthened severally by the change which has taken place -in the spectrum of the new star since Vögel observed it, but -an additional argument of overwhelming force has been -introduced. If any one of the suns died out, a crust forming -over its surface and this crust being either absolutely -dark or only shining with very feeble lustre, the sun would -still in one respect resemble all the suns which are spread -over the heavens—it would show no visible disc, however -great the telescopic power used in observing it. If the -nearest of all the stars were as large, or even a hundred -times as large, as Sirius, and were observed with a telescope -of ten times greater magnifying power than any yet<span class="pagenum"><a id="Page_131">131</a></span> -directed to the heavens, it would appear only as a point of -light. If it lost the best part of its lustre, it would appear -only as a dull point of light. Now the planetary -nebulæ show discs, sometimes of considerable breadth. -Sir J. Herschel, to whom and to Sir W. Herschel we owe -the discovery and observation of nearly all these objects, -remarks that “the planetary nebulæ have, as their name -imports, a near, in some instances a perfect, resemblance -to planets, presenting discs round, or slightly oval, in -some quite sharply terminated, in others a little hazy or -softened at the borders....” Among the most remarkable -may be specified one near the Cross, whose light is -about equal to that of a star just visible to the naked eye, -“its diameter about twelve seconds, its disc circular or very -slightly elliptic, and with a clear, sharp, well-defined outline, -having exactly the appearance of a planet, with the exception -of its colour, which is a fine and full blue, verging -somewhat upon green.” But the largest of these planetary -nebulæ, not far from the southernmost of the two stars called -the Pointers, has a diameter of 2⅔ minutes of arc, “which, -supposing it placed at a distance from us not greater than -that of the nearest known star of our northern heavens, -would imply a linear diameter seven times greater than that -of the orbit of Neptune.” The actual volume of this -object, on this assumption, would exceed our sun’s ten -million million times. No one supposes that this planetary -nebula, shining with a light indicative of gaseity, has a mass -exceeding our sun’s in this enormous degree. It probably -has so small a mean density as not greatly to exceed, or -perhaps barely to equal, our sun in mass. Now though the -“new star” in Cygnus presented no measurable disc, and -still shines as a mere blue point in the largest telescope, yet -inasmuch as its spectrum associated it with the planetary and -gaseous nebulæ, which we know to be much larger bodies -than the stars, it must be regarded, in its present condition, -as a planetary nebula, though a small one; and since we -cannot for a moment imagine that the monstrous planetary<span class="pagenum"><a id="Page_132">132</a></span> -nebulæ just described are bodies which once were suns, but -whose crust has now become non-luminous, while around -the crust masses of gas shine with a faint luminosity, so -are we precluded from believing that this smaller member -of the same family is in that condition.</p> - -<p>It <em>is</em> conceivable (and the possibility must be taken into -account in any attempt to interpret the phenomena of the -new star) that when shining as a star, the new orb, so far as -this unusual lustre was concerned, was of sunlike dimensions. -For we cannot tell whether the surface which gave the strong -light was less or greater than, or equal to, that which is now -shining with monochromatic light. Very likely, if we had -been placed where we could have seen the full dimensions of -the planetary nebula as it at present exists, we should have -found only its nuclear part glowing suddenly with increased -lustre, which, after very rapidly attaining its maximum, -gradually died out again, leaving the nebula as it had been -before. But that the mass now shining with monochromatic -light is, I will not say enormously large, but of exceedingly -small mean density, so that it is enormously large compared -with the dimensions it would have if its entire substance -were compressed till it had the same mean density as our -own sun, must be regarded as, to all intents and purposes, -certain.</p> - -<p>We certainly have not here, then, the case of a sun -which has grown old and dead and dark save at the surface, -but within whose interior fire has still remained, only waiting -some disturbing cause to enable it for a while to rush forth. -If we could suppose that in such a case there <em>could</em> be such -changes as the spectroscope has indicated—that the bright -lines of the gaseous outbursting matter would, during the -earlier period of the outburst, show on a bright continuous -background, due to the glowing lips of the opening through -which the matter had rushed, but later would shine alone, -becoming also fewer in number, till at last only one was left,—we -should find ourselves confronted with the stupendous -difficulty that that single remaining line is the bright line of<span class="pagenum"><a id="Page_133">133</a></span> -the planetary and other gaseous nebulæ. Any hypothesis -accounting for its existence in the spectrum of the faint blue -starlike object into which the star in Cygnus has faded ought -to be competent to explain its existence in the spectrum of -those nebulæ. But <em>this</em> hypothesis certainly does not so -explain its existence in the nebular spectrum. The nebulæ -cannot be suns which have died out save for the light of -gaseous matter surrounding them, for they are millions, or -rather millions of millions, of times too large. If, for instance, -a nebula, like the one above described as lying near -the southernmost Pointer, were a mass of this kind, having -the same mean density as the sun, and lying only at the -distance of the nearest of the stars from us, then not only -would it have the utterly monstrous dimensions stated by Sir -J. Herschel, but it would in the most effective way perturb the -whole solar system. With a diameter exceeding seven times -that of the orbit of Neptune, it would have a volume, and -therefore a mass, exceeding our sun’s volume and mass -more than eleven millions of millions of times. But its distance -on this assumption would be only about two hundred -thousand times the sun’s, and its attraction reduced, as -compared with his, on this account only forty thousand -millions of times. So that its attraction on the sun and -on the earth would be greater than his attraction on the -earth, in the same degree that eleven millions are greater -than forty thousand—or two hundred and seventy-five times. -The sun, despite his enormous distance from such a mass, -would be compelled to fall very quickly into it, unless he -circuited (with all his family) around it in about one-sixteenth -of a year, which most certainly he does not do. Nor -would increasing the distance at which we assume the star -to lie have any effect to save the sun from being thus perturbed, -but the reverse. If we double for instance our estimate -of the nebula’s distance, we increase eightfold our -estimate of its mass, while we only diminish its attraction on -our sun fourfold on account of increased distance; so that -now its attraction on our sun would be one-fourth its former<span class="pagenum"><a id="Page_134">134</a></span> -attraction multiplied by eight, or twice our former estimate. -We cannot suppose the nebula to be much nearer than -the nearest star. Again, we cannot suppose that the light -of these gaseous nebulæ comes from some bright orb within -them of only starlike apparent dimensions, for in that case -we should constantly recognize such starlike nucleus, which -is not the case. Moreover, the bright-line spectrum from -one of these nebulæ comes from the whole nebula, as is -proved by the fact that if the slit of the spectroscope be -opened it becomes possible to see three spectroscopic -images of the nebula itself, not merely the three bright lines.</p> - -<p>So that, if we assume the so-called star in Cygnus to -be now like other objects giving the same monochromatic -spectrum—and this seems the only legitimate assumption—we -are compelled to believe that the light now reaching us -comes from a nebulous mass, not from the faintly luminous -envelope of a dead sun. Yet, remembering that when at its -brightest this orb gave a spectrum resembling in general -characteristics that of other stars or suns, and closely resembling -even in details that of stars like Gamma Cassiopeiæ, -we are compelled by parity of reasoning to infer that -when the so-called new star was so shining, the greater -part of its light came from a sunlike mass. Thus, then, -we are led to the conclusion that in the case of this body -we have a nucleus or central mass, and that around this -central mass there is a quantity of gaseous matter, -resembling in constitution that which forms the bulk of the -other gaseous nebulæ. The denser nucleus ordinarily shines -with so faint a lustre that the continuous spectrum from its -light is too faint to be discerned with the same spectroscopic -means by which the bright lines of the gaseous portion are -shown; and the gaseous portion ordinarily shines with so -faint a lustre that its bright lines would not be discernible -on the continuous background of a stellar spectrum. -Through some cause unknown—possibly (as suggested in -an article on the earlier history of this same star in my -“Myths and Marvels of Astronomy”) the rush of a rich<span class="pagenum"><a id="Page_135">135</a></span> -and dense flight of meteors upon the central mass—the -nucleus was roused to a degree of heat far surpassing its -ordinary temperature. Thus for a time it glowed as a sun. -At the same time the denser central portions of the nebulous -matter were also aroused to intenser heat, and the bright -lines which ordinarily (and certainly at present) would not -stand out bright against the rainbow-tinted background of a -stellar spectrum, showed brightly upon the continuous spectrum -of the new star. Then as the rush of meteors upon -the nucleus and on the surrounding nebulous matter ceased—if -that be the true explanation of the orb’s accession of -lustre—or as the cause of the increase of brightness, whatever -that cause may have been, ceased to act, the central -orb slowly returned to its usual temperature, the nebulous -matter also cooling, the continuous spectrum slowly fading -out, the denser parts of the nebulous matter exercising also -a selective absorption (explaining the bands seen in the -spectrum at this stage) which gradually became a continuous -absorption—that is, affected the entire spectrum. Those -component gases, also, of the nebulous portion which had -for a while been excited to sufficient heat to show their -bright lines, cooled until their lines disappeared, and none -remained visible except for a while the three usual nebular -lines, and latterly (owing to still further cooling) only the -single line corresponding to the monochromatic light of the -fainter gaseous nebulæ.</p> - -<hr /> - -<p><span class="pagenum"><a id="Page_136">136</a></span></p> - -<div class="chapter"> -<h2><a id="STAR-GROUPING_STAR-DRIFT_AND_STAR-MIST"></a><i>STAR-GROUPING, STAR-DRIFT, AND STAR-MIST.</i><br /> - -<span class="subhead"><i>A Lecture delivered at the Royal Institution on May 6, 1870.</i></span></h2> -</div> - -<p class="in0">Nearly a century has passed since the greatest astronomer -the world has ever known—the Newton of observational -astronomy, as he has justly been called by Arago—conceived -the daring thought that he would gauge the -celestial depths. And because in his day, as indeed in our -own, very little was certainly known respecting the distribution -of the stars, he was forced to found his researches upon -a guess. He supposed that the stars, not only those visible -to the naked eye, but all that are seen in the most powerful -telescopes, are suns, distributed with a certain general -uniformity throughout space. It is my purpose to attempt -to prove that—as Sir Wm. Herschel was himself led to -suspect during the progress of his researches—this guess was -a mistaken one; that but a small proportion of the stars can -be regarded as real suns; and that in place of the uniformity -of distribution conceived by Sir Wm. Herschel, the chief -characteristic of the sidereal system is <em>infinite variety</em>.</p> - -<p>In order that the arguments on which these views are -based may be clearly apprehended, it will be necessary to -recall the main results of Sir Wm. Herschel’s system of -star-grouping.</p> - -<p>Directing one of his 20-feet reflectors to different parts of<span class="pagenum"><a id="Page_137">137</a></span> -the heavens, he counted the stars seen in the field of view. -Assuming that the telescope really reached the limits of the -sidereal system, it is clear that the number of stars seen -in any direction affords a means of estimating the relative -extension of the system in that direction, provided always -that the stars are really distributed throughout the system -with a certain approach to uniformity. Where many stars -are seen, there the system has its greatest extension; where -few, there the limits of the system must be nearest to us.</p> - -<p>Sir Wm. Herschel was led by this process of star-grouping -to the conclusion that the sidereal system has the figure -of a cloven disc. The stars visible to the naked eye lie far -within the limits of this disc. Stars outside the relatively -narrow limits of the sphere including all the visible stars, are -separately invisible. But where the system has its greatest -extension these orbs produce collectively the diffused light -which forms the Milky Way.</p> - -<p>Sir John Herschel, applying a similar series of researches -to the southern heavens, was led to a very similar conclusion. -His view of the sidereal system differs chiefly in this respect -from his father’s, that he considered the stars within certain -limits of distance from the sun to be spread less richly -through space than those whose united lustre produces -the milky light of the galaxy.</p> - -<p>Now it is clear that if the supposition on which these -views are based is just, the three following results are to be -looked for.</p> - -<p>In the first place, the stars visible to the naked eye would -be distributed with a certain general uniformity over the -celestial sphere; so that if on the contrary we find certain -extensive regions over which such stars are strewn much -more richly than over the rest of the heavens, we must -abandon Sir Wm. Herschel’s fundamental hypothesis and all -the conclusions which have been based upon it.</p> - -<p>In the second place, we ought to find no signs of the -aggregation of lucid stars into streams or clustering groups. -If we should find such associated groups, we must abandon<span class="pagenum"><a id="Page_138">138</a></span> -the hypothesis of uniform distribution and all the conclusions -founded on it.</p> - -<p>Thirdly, and most obviously of all, the lucid stars ought -not to be associated in a marked manner with the figure of -the Milky Way. To take an illustrative instance. When -we look through a glass window at a distant landscape we do -not find that the specks in the substance of the glass seem -to follow the outline of valleys, hills, trees, or whatever -features the landscape may present. In like manner, regarding -the sphere of the lucid stars as in a sense the window -through which we view the Milky Way, we ought not to find -these stars, which are so near to us, associated with the -figure of the Milky Way, whose light comes from distances -so enormously exceeding those which separate us from the -lucid stars. Here again, then, if there should appear signs -of such association, we must abandon the theory that the -sidereal system is constituted as Sir Wm. Herschel supposed.</p> - -<p>It should further be remarked that the three arguments -derived from these relations are independent of each other. -They are not as three links of a chain, any one of which -being broken the chain is broken. They are as three strands -of a triple cord. If one strand holds, the cord holds. It -may be shown that all three are to be trusted.</p> - -<p>It is not to be expected, however, that the stars as -actually seen should exhibit these relations, since far the -larger number are but faintly visible; so that the eye would -look in vain for the signs of law among them, even though -law may be there. What is necessary is that maps should -be constructed on a uniform and intelligible plan, and that -in these maps the faint stars should be made bright, and the -bright stars brighter.</p> - -<p>The maps exhibited during this discourse [since published -as my “Library Atlas”] have been devised for this -purpose amongst others. There are twelve of them, but -they overlap, so that in effect each covers a tenth part of -the heavens. There is first a north-polar map, then five -maps symmetrically placed around it; again, there is a<span class="pagenum"><a id="Page_139">139</a></span> -south-polar map, and five maps symmetrically placed round -that map; and these five so fit in with the first five as -to complete the enclosure of the whole sphere. In effect, -every map of the twelve has five maps symmetrically placed -around it and overlapping it.</p> - -<p>Since the whole heavens contain but 5932 stars visible -to the naked eye, each of the maps should contain on the -average about 593 stars. But instead of this being the case, -some of the maps contain many more than their just proportion -of stars, while in others the number as greatly falls -short of the average. One recognizes, by combining these -indications, the existence of a roughly circular region, rich -in stars, in the northern heavens, and of another, larger and -richer, in the southern hemisphere.</p> - -<p>To show the influence of these rich regions, it is only -necessary to exhibit the numerical relations presented by the -maps.</p> - -<p>The north-polar map, in which the largest part of the -northern rich region falls, contains no less than 693 lucid -stars, of which upwards of 400 fall within the half corresponding -to the rich region. Of the adjacent maps, two -contain upwards of 500 stars, while the remaining three -contain about 400 each. Passing to the southern hemisphere, -we find that the south-polar map, which falls wholly -within a rich region, contains no less than 1132 stars! One -of the adjacent maps contains 834 stars, and the four -others exhibit numbers ranging from 527 to 595.</p> - -<p>It is wholly impossible not to recognize so unequal a -distribution as exhibiting the existence of special laws of -stellar aggregation.</p> - -<p>It is noteworthy, too, that the greater Magellanic cloud -falls in the heart of the southern rich region. Were there -not other signs that this wonderful object is really associated -with the sidereal system, it might be rash to recognize this -relation as indicating the existence of a physical connection -between the Nubecula Major and the southern region rich -in stars. Astronomers have indeed so long regarded the<span class="pagenum"><a id="Page_140">140</a></span> -Nubeculæ as belonging neither to the sidereal nor to the -nebular systems, that they are not likely to recognize very -readily the existence of any such connection. Yet how -strangely perverse is the reasoning which has led astronomers -so to regard these amazing objects. Presented fairly, -that reasoning amounts simply to this: The Magellanic -clouds contain stars and they contain nebulæ; therefore -they are neither nebular nor stellar. Can perversity of -reasoning be pushed further? Is not the obvious conclusion -this, that since nebulæ and stars are <em>seen</em> to be intermixed -in the Nubeculæ, the nebular and stellar systems form in -reality but one complex system?</p> - -<p>As to the existence of star-streams and clustering aggregations, -we have also evidence of a decisive character. -There is a well-marked stream of stars running from near -Capella towards Monoceros. Beyond this lies a long dark -rift altogether bare of lucid orbs, beyond which again lies an -extensive range of stars, covering Gemini, Cancer, and the -southern parts of Leo. This vast system of stars resembles -a gigantic sidereal billow flowing towards the Milky Way as -towards some mighty shore-line. Nor is this description -altogether fanciful; since one of the most marked instances -of star-drift presently to be adduced refers to this very -region. These associated stars <em>are</em> urging their way towards -the galaxy, and that at a rate which, though seemingly slow -when viewed from beyond so enormous a gap as separates us -from this system, must in reality be estimated by millions of -miles in every year.</p> - -<p>Other streams and clustering aggregations there are -which need not here be specially described. But it is -worth noticing that all the well-marked streams recognized -by the ancients seem closely associated with the southern -rich region already referred to. This is true of the stars -forming the River Eridanus, the serpent Hydra, and the -streams from the water-can of Aquarius. It is also noteworthy -that in each instance a portion of the stream lies -outside the rich region, the rest within it; while all the<span class="pagenum"><a id="Page_141">141</a></span> -streams which lie on the same side of the galaxy tend -towards the two Magellanic clouds.</p> - -<p>Most intimate signs of association between lucid stars -and the galaxy can be recognized—(i.) in the part extending -from Cygnus to Aquila; (ii.) in the part from Perseus to -Monoceros; (iii.) over the ship Argo; and (iv.) near Crux -and the feet of Centaurus.</p> - -<p>Before proceeding to the subject of Star-drift, three -broad facts may be stated. They are, I believe, now -recognized for the first time, and seem decisive of the -existence of special laws of distribution among the stars:—</p> - -<p>First, the rich southern region, though covering but a -sixth part of the heavens, contains one-third of all the lucid -stars, leaving only two-thirds for the remaining five-sixths of -the heavens.</p> - -<p>Secondly, if the two rich regions and the Milky Way be -considered as one part of the heavens, the rest as another, -then the former part is three times as richly strewn with lucid -stars as the second.</p> - -<p>Thirdly, the southern hemisphere contains one thousand -more lucid stars than the northern, a fact which cannot but -be regarded as most striking when it is remembered that the -total number of stars visible to ordinary eyesight in both -hemispheres falls short of 6000.</p> - -<p>Two or three years ago, the idea suggested itself to me -that if the proper motions of the stars were examined, they -would be found to convey clear information respecting the -existence of variety of structure, and special laws of distribution -within the sidereal system.</p> - -<p>In the first place, the mere amount of a star’s apparent -motion must be regarded as affording a means of estimating -the star’s distance. The nearer a moving object is, the -faster it will seem to move, and <i xml:lang="la" lang="la">vice versâ</i>. Of course in -individual instances little reliance can be placed on this -indication; but by taking the average proper motions of a -set of stars, a trustworthy measure may be obtained of their -average distance, as compared with the average distance of -another set.</p> - -<p><span class="pagenum"><a id="Page_142">142</a></span> -For example, we have in this process the means of -settling the question whether the apparent brightness of a -star is indeed a test of relative nearness. According to -accepted theories the sixth-magnitude stars are ten or twelve -times as far off as those of the first magnitude. Hence their -motions should, on the average, be correspondingly small. -Now, to make assurance doubly sure, I divided the stars into -two sets, the first including the stars of the 1st, 2nd, and 3rd, -the second including those of the 4th, 5th, and 6th magnitude. -According to accepted views, the average proper motion for -the first set should be about five times as great as that for -the second. I was prepared to find it about three times as -great; that is, not so much greater as the accepted theories -require, but still considerably greater. To my surprise, I -found that the average proper motion of the brighter orders -of stars is barely equal to that of the three lower orders.</p> - -<p>This proves beyond all possibility of question that by far -the greater number of the fainter orders of stars (I refer here -throughout to lucid stars) owe their faintness not to vastness -of distance, but to real relative minuteness.</p> - -<p>To pass over a number of other modes of research, the -actual mapping of the stellar motions, and the discovery of -the peculiarity to which I have given the name of star-drift, -remain to be considered.</p> - -<p>In catalogues it is not easy to recognize any instances of -community of motion which may exist among the stars, -owing to the method in which the stars are arranged. What -is wanted in this case (as in many others which yet remain to -be dealt with) is the adoption of a plan by which such -relations may be rendered obvious to the eye. The plan I -adopted was to attach to each star in my maps a small arrow, -indicating the amount and direction of that star’s apparent -motion in 36,000 years (the time-interval being purposely -lengthened, as otherwise most of the arrows would have -been too small to be recognized). When this was done, -several well-marked instances of community of motion could -immediately be recognized.</p> - -<p><span class="pagenum"><a id="Page_143">143</a></span> -It is necessary to premise, however, that before the experiment -was tried, there were reasons for feeling very -doubtful whether it would succeed. A system of stars -might really be drifting athwart the heavens, and yet the -drift might be rendered unrecognizable through the intermixture -of more distant or nearer systems having motions of -another sort and seen accidentally in the same general -direction.</p> - -<p>This was found to be the case, indeed, in several -instances. Thus the stars in the constellation Ursa Major, -and neighbouring stars in Draco, exhibit two well-marked -directions of drift. The stars β, γ, δ, ε, and ζ of the Great -Bear, besides two companions of the last-named star, are -travelling in one direction, with equal velocity, and clearly -form one system. The remaining stars in the neighbourhood -are travelling in a direction almost exactly the reverse. But -even this relation, thus recognized in a region of diverse -motions, is full of interest. Baron Mädler, the well-known -German astronomer, recognizing the community of motion -between ζ Ursæ and its companions, calculated the cyclic -revolution of the system to be certainly not less than 7000 -years. But when the complete system of stars showing this -motion is considered, we get a cyclic period so enormous, -that not only the life of man, but the life of the human race, -the existence of our earth, nay, even the existence of the -solar system, must be regarded as a mere day in comparison -with that tremendous cycle.</p> - -<p>Then there are other instances of star-drift where, though -two directions of motion are not intermixed, the drifting -nature of the motion is not at once recognized, because -of the various distances at which the associated stars lie -from the eye.</p> - -<p>A case of this kind is to be met with in the stars -forming the constellation Taurus. It was here that Mädler -recognized a community of motion among the stars, but he -did not interpret this as I do. He had formed the idea -that the whole of the sidereal system must be in motion<span class="pagenum"><a id="Page_144">144</a></span> -around some central point; and for reasons which need -not here be considered, he was led to believe that in -whatever direction the centre of motion may lie, the stars -seen in that general direction would exhibit a community -of motion. Then, that he might not have to examine the -proper motions all over the heavens, he inquired in what -direction (in all probability) the centre of motion may be -supposed to lie. Coming to the conclusion that it must -lie towards Taurus, he examined the proper motions in that -constellation, and found a community of motion which led -him to regard Alcyone, the chief star of the Pleiades, as the -centre around which the sidereal system is moving. Had -he examined further he would have found more marked -instances of community of motion in other parts of the -heavens, a circumstance which would have at once compelled -him to abandon his hypothesis of a central sun in the -Pleiades, or at least to lay no stress on the evidence -derivable from the community of motion in Taurus.</p> - -<p>Perhaps the most remarkable instance of star-drift is that -observed in the constellations Gemini and Cancer. Here -the stars seem to set bodily towards the neighbouring part of -the Milky Way. The general drift in that direction is too -marked, and affects too many stars, to be regarded as by -any possibility referable to accidental coincidence.</p> - -<p>It is worthy of note that if the community of star-drift -should be recognized (or I prefer to say, <em>when</em> it is recognized), -astronomers will have the means of determining the -relative distances of the stars of a drifting system. For -differences in the apparent direction and amount of motion -can be due but to differences of distance and position, and -the determination of these differences becomes merely a -question of perspective.<a id="FNanchor_18" href="#Footnote_18" class="fnanchor">18</a></p> - -<p>Before long it is likely that the theory of star-drift will -be subjected to a crucial test, since spectroscopic analysis -affords the means of determining the stellar motions of<span class="pagenum"><a id="Page_145">145</a></span> -recess or approach. The task is a very difficult one, but -astronomers have full confidence that in the able hands of -Mr. Huggins it will be successfully accomplished. I await -the result with full confidence that it will confirm my views. -(See pages <a href="#Page_92">92–94</a> for the result.)</p> - -<div class="tb">* <span class="in2">* </span><span class="in2">* </span><span class="in2">* </span><span class="in2">*</span></div> - -<p>Turning to the subject of Star-mist, under which head I -include all orders of nebulæ, I propose to deal with but a -small proportion of the evidence I have collected to prove -that none of the nebulæ are external galaxies. That evidence -has indeed become exceedingly voluminous.</p> - -<p>I shall dwell, therefore, on three points only.</p> - -<p>First, as to the distribution of the nebulæ:—They are -not spread with any approach to uniformity over the heavens, -but are gathered into streams and clusters. The one great -law which characterizes their distribution is an avoidance of -the Milky Way and its neighbourhood. This peculiarity has, -strangely enough, been regarded by astronomers as showing -that there is no association between the nebulæ and the -sidereal system. They have forgotten that marked contrast -is as clear a sign of association as marked resemblance, and -has always been so regarded by logicians.</p> - -<p>Secondly, there are in the southern heavens two well-marked -streams of nebulæ. Each of these streams is associated -with an equally well-marked stream of stars. Each -intermixed stream directs its course towards a Magellanic -Cloud, one towards the Nubecula Minor, the other towards -the Nubecula Major. To these great clusters they flow, -like rivers towards some mighty lake. And within these -clusters, which are doubtless roughly spherical in form, there -are found intermixed in wonderful profusion, stars, star-clusters, -and all the orders of nebulæ. Can these coincidences -be regarded as accidental? And if not accidental, -is not the lesson they clearly teach us this, that nebulæ form -but portions of the sidereal system, associating themselves -with stars on terms of equality (if one may so speak), even if -single stars be not more important objects in the scale of<span class="pagenum"><a id="Page_146">146</a></span> -creation than these nebulous masses, which have been so -long regarded as equalling, if not outvying, the sidereal -system itself in extent?</p> - -<p>The third point to which I wish to invite attention is the -way in which in many nebulæ stars of considerable relative -brightness, and belonging obviously to the sidereal system, -are so associated with nebulous masses as to leave no doubt -whatever that these masses really cling around them. The -association is in many instances far too marked to be regarded -as the effect of accident.</p> - -<p>Among other instances<a id="FNanchor_19" href="#Footnote_19" class="fnanchor">19</a> may be cited the nebula round -the stars <i>c</i>¹ and <i>c</i>² in Orion. In this object two remarkable -nebulous nodules centrally surround two double stars. -Admitting the association here to be real (and no other -explanation can reasonably be admitted), we are led to interesting -conclusions respecting the whole of that wonderful -nebulous region which surrounds the sword of Orion. We -are led to believe that the other nebulæ in that region are -really associated with the fixed stars there; that it is not a -mere coincidence, for instance, that the middle star in the -belt of Orion is involved in nebula, or that the lowest star -of the sword is similarly circumstanced. It is a legitimate -inference from the evidence that all the nebulæ in this region -belong to one great nebulous group, which extends its -branches to these stars. As a mighty hand, this nebulous -region seems to gather the stars here into close association, -showing us, in a way there is no misinterpreting, that these -stars form one system.</p> - -<p>The nebula around the strange variable star, Eta Argûs, -is another remarkable instance of this sort. More than two -years ago I ventured to make two predictions about this -object. The first was a tolerably safe one. I expressed my -belief that the nebula would be found to be gaseous. After -Mr. Huggins’s discovery that the great Orion nebula is -gaseous, it was not difficult to see that the Argo nebula must<span class="pagenum"><a id="Page_147">147</a></span> -be so too. At any rate, this has been established by -Captain Herschel’s spectroscopic researches. The other -prediction was more venturesome. Sir John Herschel, -whose opinion on such points one would always prefer to -share, had expressed his belief that the nebula lies far out in -space beyond the stars seen in the same field of view. I -ventured to express the opinion that those stars are involved -in the nebula. Lately there came news from Australia that -Mr. Le Sueur, with the great reflector erected at Melbourne, -has found that the nebula has changed largely in shape -since Sir John Herschel observed it. Mr. Le Sueur accordingly -expressed his belief that the nebula lies <em>nearer</em> to us -than the fixed stars seen in the same field of view. More -lately, however, he has found that the star Eta Argûs is -shining with the light of burning hydrogen, and he expresses -his belief that the star has consumed the nebulous matter -near it. Without agreeing with this view, I recognize in it a -proof that Mr. Le Sueur now considers the nebula to be -really associated with the stars around it. My belief is that -as the star recovers its brilliancy observation will show that -the nebula in its immediate neighbourhood becomes brighter -(<em>not</em> fainter through being consumed as fuel). In fact, I am -disposed to regard the variations of the nebula as systematic, -and due to orbital motions among its various portions around -neighbouring stars.</p> - -<p>As indicative of other laws of association bearing on the -relations I have been dealing with, I may mention the circumstance -that red stars and variable stars affect the neighbourhood -of the Milky Way or of well-marked star-streams. -The constellation Orion is singularly rich in objects of this -class. It is here that the strange “variable” Betelgeux lies. -At present this star shows no sign of variation, but a few -years ago it exhibited remarkable changes. One is invited -to believe that the star may have been carried by its proper -motion into regions where there is a more uniform distribution -of the material whence this orb recruits its fires. It may be -that in the consideration of such causes of variation affecting<span class="pagenum"><a id="Page_148">148</a></span> -our sun in long past ages a more satisfactory explanation -than any yet obtained may be found of the problem -geologists find so perplexing—the former existence of a -tropical climate in places within the temperate zone, or even -near the Arctic regions.<a id="FNanchor_20" href="#Footnote_20" class="fnanchor">20</a></p> - -<div class="tb">* <span class="in2">* </span><span class="in2">* </span><span class="in2">* </span><span class="in2">*</span></div> - -<p>It remains that I should exhibit the general results to -which I have been led. It has seemed to many that my -views tend largely to diminish our estimate of the extent -of the sidereal system. The exact reverse is the case. -According to accepted views there lie within the range of -our most powerful telescopes millions of millions of suns. -According to mine the primary suns within the range of our -telescopes must be counted by tens of thousands, or by -hundreds of thousands at the outside. What does this -diminution of numbers imply but that the space separating -sun from sun is enormously greater than accepted theories -would permit? And this increase implies an enormous -increase in the estimate we are to form of the vital energies -of individual suns. For the vitality of a sun, if one may -be permitted the expression, is measured not merely by the -amount of matter over which it exercises control, but by -the extent of space within which that matter is distributed. -Take an orb a thousand times vaster than our sun, and -spread over its surface an amount of matter exceeding a -thousandfold the combined mass of all the planets of the -solar system:—So far as living force is concerned, the result -is—<em>nil</em>. But distribute that matter throughout a vast space -all round the orb:—That orb becomes at once fit to be the -centre of a host of dependent worlds. Again, according -to accepted theories, when the astronomer has succeeded -in resolving the milky light of a portion of the galaxy into -stars, he has in that direction, at any rate, reached the limits -of the sidereal system. According to my views, what he<span class="pagenum"><a id="Page_149">149</a></span> -has really done has been but to analyze a definite aggregation -of stars, a mere corner of that great system. Yet once -more, according to accepted views, thousands and thousands -of galaxies, external to the sidereal system, can be seen -with powerful telescopes. If I am right, the external star-systems -lie far beyond the reach of the most powerful -telescope man has yet been able to construct, insomuch -that perchance the nearest of the outlying galaxies may lie -a million times beyond the range even of the mighty mirror -of the great Rosse telescope.</p> - -<p>But this is little. Wonderful as is the extent of the -sidereal system as thus viewed, even more wonderful is its -infinite variety. We know how largely modern discoveries -have increased our estimate of the complexity of the planetary -system. Where the ancients recognized but a few -planets, we now see, besides the planets, the families of -satellites; we see the rings of Saturn, in which minute -satellites must be as the sands on the sea-shore for multitude; -the wonderful zone of asteroids; myriads on myriads -of comets; millions on millions of meteor-systems, gathering -more and more richly around the sun, until in his neighbourhood -they form the crown of glory which bursts into view -when he is totally eclipsed. But wonderful as is the variety -seen within the planetary system, the variety within the -sidereal system is infinitely more amazing. Besides the -single suns, there are groups and systems and streams of -primary suns; there are whole galaxies of minor orbs; -there are clustering stellar aggregations, showing every -variety of richness, of figure, and of distribution; there are -all the various forms of nebulæ, resolvable and irresolvable, -circular, elliptical, and spiral; and lastly, there are irregular masses -of luminous gas, clinging in fantastic convolutions -around stars and star-systems. Nor is it unsafe to assert -that other forms and variety of structure will yet be discovered, -or that hundreds more exist which we may never -hope to recognize.</p> - -<p>But lastly, even more wonderful than the infinite variety<span class="pagenum"><a id="Page_150">150</a></span> -of the sidereal system, is its amazing vitality. Instead of -millions of inert masses, we see the whole heavens instinct -with energy—astir with busy life. The great masses of -luminous vapour, though occupying countless millions of -cubic miles of space, are moved by unknown forces like -clouds before the summer breeze; star-mist is condensing -into clusters; star-clusters are forming into suns; streams -and clusters of minor orbs are swayed by unknown attractive -energies; and primary suns singly or in systems are pursuing -their stately path through space, rejoicing as giants to run -their course, extending on all sides the mighty arm of their -attraction, gathering from ever-new regions of space supplies -of motive energy, to be transformed into the various forms -of force—light and heat and electricity—and distributed -in lavish abundance to the worlds which circle round them.</p> - -<p>Truly may I say, in conclusion, that whether we regard -its vast extent, its infinite variety, or the amazing vitality -which pervades its every portion, the sidereal system is, of -all the subjects man can study, the most imposing and the -most stupendous. It is as a book full of mighty problems—of -problems which are as yet almost untouched by man, -of problems which it might seem hopeless for him to attempt -to solve. But those problems are given to him for solution, -and he <em>will</em> solve them, whenever he dares attempt to decipher -aright the records of that wondrous volume.</p> - -<hr /> - -<p><span class="pagenum"><a id="Page_151">151</a></span></p> - -<div class="chapter"> -<h2><a id="MALLETS_THEORY_OF_VOLCANOES"></a><i>MALLET’S THEORY OF VOLCANOES.</i></h2> -</div> - -<p class="in0">There are few subjects less satisfactorily treated in scientific -treatises than that which Humboldt calls the Reaction -of the Earth’s Interior. We find, not merely in the configuration -of the earth’s crust, but in actual and very -remarkable phenomena, evidence of subterranean forces of -great activity; and the problems suggested seem in no sense -impracticable: yet no theory of the earth’s volcanic energy -has yet gained general acceptance. While the astronomer -tells us of the constitution of orbs millions of times further -away than our own sun, the geologist has hitherto been -unable to give an account of the forces which agitate the -crust of the orb on which we live.</p> - -<p>The theory put forward respecting volcanic energy, however, -by the eminent seismologist Mallet, promises not -merely to take the place of all others, but to gain a degree -of acceptance which has not been accorded to any theory -previously enunciated. It is, in principle, exceedingly -simple, though many of the details (into which I do not -propose to enter) involve questions of considerable difficulty.</p> - -<p>Let us, in the first place, consider briefly the various -explanations which had been already advanced.</p> - -<p>There was first the chemical theory of volcanic energy, the -favourite theory of Sir Humphry Davy. It is possible to -produce on a small scale nearly all the phenomena due to -subterranean activity, by simply bringing together certain<span class="pagenum"><a id="Page_152">152</a></span> -substances, and leaving them to undergo the chemical changes -due to their association. As a familiar instance of explosive -action thus occasioned, we need only mention the results -experienced when any one unfamiliar with the methods of -treating lime endeavours over hastily to “slake” or “slack” -it with water. Indeed, one of the strong points of the -chemical theory consisted in the circumstance that volcanoes -only occur where water can reach the subterranean -regions—or, as Mallet expresses it, that “without water -there is no volcano.” But the theory is disposed of by the -fact, now generally admitted, that the chemical energies of -our earth’s materials were almost wholly exhausted before -the surface was consolidated.</p> - -<p>Another inviting theory is that according to which the -earth is regarded as a mere shell of solid matter surrounding -a molten nucleus. There is every reason to believe -that the whole interior of the earth is in a state of intense -heat; and if the increase of heat with depth (as shown in -our mines) is supposed to continue uniformly, we find that -at very moderate depths a degree of heat must prevail -sufficient to liquefy any known solids under ordinary conditions. -But the conditions under which matter exists a -few miles only below the surface of the earth are not -ordinary. The pressure enormously exceeds any which our -physicists can obtain experimentally. The ordinary distinction -between solids and liquids cannot exist at that -enormous pressure. A mass of cold steel could be as plastic -as any of the glutinous liquids, while the structural change -which a solid undergoes in the process of liquefying could -not take place under such pressure even at an enormously -high temperature. It is now generally admitted that if the -earth really has a molten nucleus, the solid crust must, -nevertheless, be far too thick to be in any way disturbed -by changes affecting the liquid matter beneath.</p> - -<p>Yet another theory has found advocates. The mathematician -Hopkins, whose analysis of the molten-nucleus -theory was mainly effective in showing that theory to be untenable,<span class="pagenum"><a id="Page_153">153</a></span> -suggested that there may be isolated subterranean -lakes of fiery matter, and that these may be the true seat of -volcanic energy. But such lakes could not maintain their -heat for ages, if surrounded (as the theory requires) by -cooler solid matter, especially as the theory also requires -that water should have access to them. It will be observed -also that none of the theories just described affords any -direct account of those various features of the earth’s surface—mountain -ranges, table-lands, volcanic regions, and so -on—which are undoubtedly due to the action of subterranean -forces. The theory advanced by Mr. Mallet is open -to none of these objections. It seems, indeed, competent -to explain all the facts which have hitherto appeared most -perplexing.</p> - -<p>It is recognized by physicists that our earth is gradually -parting with its heat. As it cools it contracts. Now if this -process of contraction took place uniformly, no subterranean -action would result. But if the interior contracts more -quickly than the crust, the latter must in some way or other -force its way down to the retreating nucleus. Mr. Mallet -shows that the hotter internal portion must contract faster -than the relatively cool crust; and then he shows that the -shrinkage of the crust is competent to occasion all the -known phenomena of volcanic action. In the distant ages -when the earth was still fashioning, the shrinkage produced -the <em>irregularities of level</em> which we recognize in the elevation -of the land and the depression of the ocean-bed. Then -came the period when as the crust shrank it formed <em>corrugations</em>, -in other words, when the foldings and elevations -of the somewhat thickened crust gave rise to the mountain-ranges -of the earth. Lastly, as the globe gradually lost its -extremely high temperature, the continuance of the same -process of shrinkage led no longer to the formation of ridges -and table-lands, but to local crushing-down and dislocation. -This process is still going on, and Mr. Mallet not only -recognizes here the origin of earthquakes, and of the -changes of level now in progress, but the true cause of<span class="pagenum"><a id="Page_154">154</a></span> -volcanic heat. The modern theory of heat as a form of -motion here comes into play. As the solid crust closes in -upon the shrinking nucleus, the work expended in crushing -down and dislocating the parts of the crust is transformed -into heat, by which, at the places where the process goes -on with greatest energy, “the materials of the rock so -crushed and of that adjacent to it are heated even to fusion. -The access of water to such points determines volcanic -eruption.”</p> - -<p>Now all this is not mere theorising. Mr. Mallet does -not come before the scientific world with an ingenious -speculation, which may or may not be confirmed by observation -and experiment. He has measured and weighed -the forces of which he speaks. He is able to tell precisely -what proportion of the actual energy which must be developed -as the earth contracts is necessary for the production -of observed volcanic phenomena. It is probable -that nine-tenths of those who have read these lines would -be disposed to think that the contraction of the earth must -be far too slow to produce effects so stupendous as those -which we recognize in the volcano and the earthquake. -But Mr. Mallet is able to show, by calculations which cannot -be disputed, that less than one-fourth of the heat at -present annually lost by the earth is sufficient to account for -the total annual volcanic action, according to the best data -at present in our possession.</p> - -<p>As I have said, I do not propose to follow out Mr. -Mallet’s admirable theory into all its details. I content -myself with pointing out how excellently it accounts for -certain peculiarities of the earth’s surface configuration. -Few that have studied carefully drawn charts of the chief -mountain-ranges can have failed to notice that the arrangement -of these ranges does not accord with the idea of -upheaval through the action of internal forces. But it -will be at once recognized that the aspect of the mountain-ranges -accords exactly with what would be expected -to result from such a process of contraction as Mr. Mallet<span class="pagenum"><a id="Page_155">155</a></span> -has indicated. The shrivelled skin of an apple affords no -inapt representation of the corrugated surface of our earth, -and according to the new theory, the shrivelling of such -a skin is precisely analogous to the processes at work upon -the earth when mountain-ranges were being formed. Again, -there are few students of geology who have not found a -source of perplexity in the foldings and overlappings of -strata in mountainous regions. No forces of upheaval seem -competent to produce this arrangement. But by the new -theory this feature of the earth’s surface is at once explained; -indeed, no other arrangement could be looked for.</p> - -<p>It is worthy of notice that Mr. Mallet’s theory of Volcanic -energy is completely opposed to ordinary ideas -respecting earthquakes and volcanoes. We have been -accustomed vaguely to regard these phenomena as due to -the eruptive outbursting power of the earth’s interior; we -shall now have to consider them as due to the subsidence -and shrinkage of the earth’s exterior. Mountains have not -been upheaved, but valleys have sunk down. And in -another respect the new theory tends to modify views which -have been generally entertained in recent times. Our most -eminent geologists have taught that the earth’s internal -forces may be as active now as in the epochs when the -mountain-ranges were formed. But Mr. Mallet’s theory -tends to show that the volcanic energy of the earth is a -declining force. Its chief action had already been exerted -when mountains began to be formed; what remains now -is but the minutest fraction of the volcanic energy of the -mountain-forming era; and each year, as the earth parts -with more and more of its internal heat, the sources of her -subterranean energy are more and more exhausted. The -thought once entertained by astronomers that the earth -might explode like a bomb, her scattered fragments producing -a ring of bodies resembling the zone of asteroids, -seems further than ever from probability; if ever there was -any danger of such a catastrophe, the danger has long since -passed away.</p> - -<hr /> - -<p><span class="pagenum"><a id="Page_156">156</a></span></p> - -<div class="chapter"> -<h2><a id="TOWARDS_THE_NORTH_POLE"></a><i>TOWARDS THE NORTH POLE.</i></h2> -</div> - -<p class="in0">The Arctic Expedition which returned to our shores in the -autumn of 1876 may be regarded as having finally decided -the question whether the North Pole of the earth is accessible -by the route through Smith’s Sound—a route which -may conveniently and properly be called the American route. -Attacks may hereafter be made on the Polar fastness from -other directions; but it is exceedingly unlikely that this -country, at any rate, will again attempt to reach the Pole -along the line of attack followed by Captain Nares’s expedition. -I may be forgiven, perhaps, for regarding Arctic -voyages made by the seamen of other nations as less likely -to be successful than those made by my own countrymen. -It is not mere national prejudice which suggests this opinion. -It is the simple fact that hitherto the most successful approaches -towards both the Northern and the Southern -Poles have been made by British sailors. Nearly a quarter -of a century has passed since Sir E. Parry made the nearest -approach to the North Pole recorded up to that time; and -although, in the interval between Parry’s expedition and -Nares’s, no expedition had been sent out from our shores -with the object of advancing towards the Pole, while -America, Sweden, Russia, and Germany sent out several, -Parry’s attempt still remained unsurpassed and unequalled. -At length it has been surpassed, but it has been by his own -countrymen. In like manner, no nation has yet succeeded -in approaching the Antarctic Pole so nearly, within many -miles, as did Captain Sir J. C. Ross in 1844. Considering<span class="pagenum"><a id="Page_157">157</a></span> -these circumstances, and remembering the success which -rewarded the efforts of Great Britain in the search for the -North-West Passage, it cannot be regarded as national prejudice -to assert that events indicate the seamen of this -country as exceptionally fitted to contend successfully -against the difficulties and the dangers of Arctic exploration. -Should England, then, give up the attempt to reach -the North Pole by way of Smith’s Sound and its northerly -prolongation, it may fairly be considered unlikely that the -Pole will ever be reached in that direction.</p> - -<p>It may be well to examine the relative probable chances -of success along other routes which have either not been so -thoroughly tried, or have been tried under less favourable -conditions.</p> - -<p>Passing over the unfortunate expedition under Hugh -Willoughby in 1553, the first attempt to penetrate within the -Polar domain was made by Henry Hudson in 1607. The -route selected was one which many regard (and I believe -correctly) as the one on which there is the best chance of -success; namely, the route across the sea lying to the west -of Spitzbergen. That Hudson, in the clumsy galleons of -Elizabeth’s time, should have penetrated to within eight -degrees and a half of the Pole, or to a distance only exceeding -Nares’s nearest approach by about 130 miles, proves -conclusively, we think, that with modern ships, and especially -with the aid of steam, this route might be followed with -much better prospect of success than that which was adopted -for Nares’s expedition. If the reader will examine a map of -the Arctic regions he will find that the western shores of -Spitzbergen and the north-eastern shores of Greenland, as -far as they have been yet explored, are separated by about -33 degrees of longitude, equivalent on the 80th parallel of -latitude to about 335 miles. Across the whole breadth of -this sea Arctic voyagers have attempted to sail northwards -beyond the 80th parallel, but no one has yet succeeded in -the attempt except on the eastern side of that sea. It was -here that Hudson—fortunately for him—directed his attack;<span class="pagenum"><a id="Page_158">158</a></span> -and he passed a hundred miles to the north of the 80th -parallel, being impeded and finally stopped by the packed -ice around the north-western shores of Spitzbergen.</p> - -<p>Let us consider the fortunes of other attempts which -have been made to approach the Pole in this direction.</p> - -<p>In 1827 Captain (afterwards Sir Edward) Parry, who had -already four times passed beyond the Arctic Circle—viz., in -1818, 1819, 1821–23, and 1824–25—made an attempt to -reach the North Pole by way of Spitzbergen. His plan was -to follow Hudson’s route until stopped by ice; then to leave -his ship, and cross the ice-field with sledges drawn by Esquimaux -dogs, and, taking boats along with the party, to cross -whatever open water they might find. In this way he succeeded -in reaching latitude 82° 45´ north, the highest ever -attained until Nares’s expedition succeeded in crossing the -83rd parallel. Parry found that the whole of the ice-field -over which his party were laboriously travelling northwards -was being carried bodily southwards, and that at length the -distance they were able to travel in a day was equalled by -the southerly daily drift of the ice-field, so that they made -no real progress. He gave up further contest, and returned -to his ship the <i>Hecla</i>.</p> - -<p>It is important to inquire whether the southerly drift -which stopped Parry was due to northerly winds or to a -southerly current; and if to the latter cause, whether this -current probably affects the whole extent of the sea in which -Parry’s ice-field was drifting. We know that his party were -exposed, during the greater part of their advance from Spitzbergen, -to northerly winds. Now the real velocity of these -winds must have been greater than their apparent velocity, -because the ice-field was moving southwards. Had this not -been the case, or had the ice-field been suddenly stopped, -the wind would have seemed stronger; precisely as it seems -stronger to passengers on board a sailing vessel when, after -being before the wind for a time, she is brought across the -wind. The ice-field was clearly travelling before the wind, -but not nearly so fast as the wind; and therefore there is<span class="pagenum"><a id="Page_159">159</a></span> -good reason for believing that the motion of the ice-field -was due to the wind alone. If we suppose this to have been -really the case, then, as there is no reason for believing that -northerly winds prevail uniformly in the Arctic regions, we -must regard Parry’s defeat as due to mischance. Another -explorer might have southerly instead of northerly winds, -and so might be assisted instead of impeded in his advance -towards the Pole. Had this been Parry’s fortune, or even if -the winds had proved neutral, he would have approached -nearer to the Pole than Nares. For Parry reckoned that he -had lost more than a hundred miles by the southerly drift of -the ice-field, by which amount at least he would have advanced -further north. But that was not all; for there can be -little doubt that he would have continued his efforts longer -but for the Sisyphæan nature of the struggle. It is true he -was nearer home when he turned back than he would have -been but for the drift, and one of his reasons for turning -back was the consideration of the distance which his men -had to travel in returning. But he was chiefly influenced (so -far as the return journey was concerned) by the danger caused -by the movable nature of the ice-field, which might at any -time begin to travel northwards, or eastwards, or westwards.</p> - -<p>If we suppose that not the wind but Arctic currents -carried the ice-field southwards, we must yet admit the probability—nay, -almost the certainty—that such currents are -only local, and occupy but a part of the breadth of the -North Atlantic seas in those high latitudes. The general -drift of the North Atlantic surface-water is unquestionably -not towards the south but towards the north; and whatever -part we suppose the Arctic ice to perform in regulating the -system of oceanic circulation—whether, with Carpenter, we -consider the descent of the cooled water as the great moving -cause of the entire system of circulation, or assign to that -motion a less important office (which seems to me the juster -opinion)—we must in any case regard the Arctic seas as a -region of surface indraught. The current flowing from those -seas, which caused (on the hypothesis we are for the moment<span class="pagenum"><a id="Page_160">160</a></span> -adopting) the southwardly motion of Parry’s ice-field, must -therefore be regarded as in all probability an exceptional -phenomenon of those seas. By making the advance from a -more eastwardly or more westwardly part of Spitzbergen, -a northerly current would probably be met with; or rather, -the motion of the ice-field would indicate the presence of -such a current, for I question very much whether open -water would anywhere be found north of the 83rd parallel. -In that case, a party might advance in one longitude and -return in another, selecting for their return the longitude in -which (always according to our present hypothesis that -currents caused the drift) Parry found that a southerly current -underlay his route across the ice. On the whole, however, -it appears to me more probable that winds, not currents, -caused the southerly drift of Parry’s ice-field.</p> - -<p>In 1868, a German expedition, under Captain Koldewey, -made the first visit to the seas west of Spitzbergen in a steamship, -the small but powerful screw steamer <i>Germania</i> (126 -tons), advancing northwards a little beyond the 81st parallel. -But this voyage can scarcely be regarded as an attempt to -approach the Pole on that course; for Koldewey’s instructions -were, “to explore the eastern coast of Greenland -northwards; and, if he found success in that direction impossible, -to make for the mysterious Island of Gilles on the -east of Spitzbergen.”</p> - -<p>Scoresby in 1806 had made thus far the most northerly -voyage in a ship on Hudson’s route, but in 1868 a Swedish -expedition attained higher latitudes than had ever or have -ever been reached by a ship in that direction. The steamship -<i>Sofia</i>, strongly built of Swedish iron, and originally -intended for winter voyages in the Baltic, was selected for -the voyage. Owing to a number of unfortunate delays, it -was not until September, 1868, that the <i>Sofia</i> reached the -most northerly part of her journey, attaining a point nearly -fifteen miles further north than Hudson had reached. To -the north broken ice was still found, but it was so closely -packed that not even a boat could pass through. Two<span class="pagenum"><a id="Page_161">161</a></span> -months earlier in the season the voyagers might have waited -for a change of wind and the breaking up of the ice; but -in the middle of September this would have been very -dangerous. The temperature was already sixteen degrees -below the freezing-point, and there was every prospect that -in a few weeks, or even days, the seas over which they had -reached their present position would be icebound. They -turned back from that advanced position; but, with courage -worthy of the old Vikings, they made another attack a -fortnight later. They were foiled again, as was to be expected, -for by this time the sun was already on the wintry -side of the equator. They had, indeed, a narrow escape -from destruction. “An ice-block with which they came -into collision opened a large leak in the ship’s side, and -when, after great exertions, they reached the land, the water -already stood two feet over the cabin floor.”<a id="FNanchor_21" href="#Footnote_21" class="fnanchor">21</a></p> - -<p>On the western side of the North Atlantic Channel—so -to term the part lying between Greenland and Spitzbergen—the -nearest approach towards the Pole was made -by the Dutch in 1670, nearly all the more recent attempts -to reach high northern latitudes in this direction having -hitherto ended in failure more or less complete.</p> - -<p>We have already seen that Captain Koldewey was -charged to explore the eastern coast of Greenland in the -<i>Germania</i> in 1868. In 1869 the <i>Germania</i> was again -despatched under his command from Bremerhaven, in -company with the <i>Hansa</i>, a sailing vessel. Lieutenant -Payer and other Austrian <i xml:lang="fr" lang="fr">savants</i> accompanied Captain -Koldewey. The attack was again made along the eastern -shores of Greenland. As far as the 74th degree the two -vessels kept company; but at this stage it happened unfortunately -that a signal from the <i>Germania</i> was misinterpreted,<span class="pagenum"><a id="Page_162">162</a></span> -and the <i>Hansa</i> left her. Soon after, the <i>Hansa</i> was crushed -by masses of drifting ice, and her crew and passengers -took refuge on an immense ice-floe seven miles in circumference. -Here they built a hut, which was in its turn -crushed. Winds and currents carried their icy home about, -and at length broke it up. Fortunately they had saved -their boats, and were able to reach Friedrichsthal, a missionary -station in the south of Greenland, whence they were -conveyed to Copenhagen in September, 1870. Returning -to the <i>Germania</i>, we find that she had a less unfortunate -experience. She entered the labyrinth of sinuous fjords, -separated by lofty promontories, and girt round by gigantic -glaciers, which characterize the eastern coast of Greenland -to the north of Scoresby Sound. In August the channels -by which she had entered were closed, and the <i>Germania</i> -was imprisoned. So soon as the ice would bear them, -Koldewey and his companions made sledging excursions -to various points around their ship. But in November -the darkness of the polar winter settled down upon them, -and these excursions ceased. The polar winter of 1869–70 -was “characterized by a series of violent northerly tempests, -one of which continued more than 100 hours, with a -velocity (measured by the anemometer) of no less than -sixty miles an hour”—a velocity often surpassed, indeed, -but which must have caused intense suffering to all who -left the shelter of the ship; for it is to be remembered -that the air which thus swept along at the rate of a mile -a minute was the bitter air of the Arctic regions. The -thermometer did not, however, descend lower than 26° -below zero, or 58° below the freezing-point—a cold often -surpassed in parts of the United States. I have myself -experienced a cold of more than 30° below zero, at -Niagara. “With proper precautions as regards shelter and -clothing,” proceeds the narrative, “even extreme cold need -not cause great suffering to those who winter in such -regions. One of the worst things to be endured is the -physical and moral weariness of being cut off from external<span class="pagenum"><a id="Page_163">163</a></span> -observations during the long night of some ninety -days, relieved only by the strange Northern Lights. The -ice accumulates all round with pressure, and assumes peculiar -and fantastic forms, emitting ever and anon ominous -noises. Fortunately, the <i>Germania</i> lay well sheltered in a -harbour opening southwards, and, being protected by a -rampart of hills on the north, was able to resist the shock -of the elements. The sun appearing once more about the -beginning of February, the scientific work of exploration -began.... The pioneers of the <i>Germania</i> advanced -as far as the 77th degree of latitude, in longitude 18° 50´ -west from Greenwich. There was no sign of an open sea -towards the Pole. <em>Had it not been for want of provisions, -the party could have prolonged their sledge journey indefinitely.</em> -The bank of ice, without remarkable protuberances, extends -to about two leagues from the shore, which from -this extreme point seems to trend towards the north-west, -where the view was bounded by lofty mountains.” As the -expedition was only equipped for one winter, it returned -to Europe in September, 1870, without having crossed the -78th parallel of north latitude.</p> - -<p>Captain Koldewey was convinced, by the results of his -exploration, that there is no continuous channel northwards -along the eastern coast of Greenland. It does not seem to -me that his expedition proved this beyond all possibility of -question. Still, it seems clear that the eastern side of the -North Atlantic is less suited than the western for the attempt -to reach the North Pole. The prevailing ocean-currents are -southerly on that side, just as they are northerly on the -western side. The cold also is greater, the lines of equal -temperature lying almost exactly in the direction of the -channel itself—that is, nearly north and south—and the cold -increasing athwart that direction, towards the west. The -nearer to Greenland the greater is the cold.<a id="FNanchor_22" href="#Footnote_22" class="fnanchor">22</a></p> - -<p><span class="pagenum"><a id="Page_164">164</a></span> -The next route to be considered in order of time would -be the American route; but I prefer to leave this to the -last, as the latest results relate to that route. I take next, -therefore, a route which some regard as the most promising -of all—that, namely, which passes between Spitzbergen and -the Scandinavian peninsula.</p> - -<p>It will be remembered that Lieutenant Payer, of the -Austrian navy, had accompanied Captain Koldewey’s first -expedition. When driven back from the attempt to advance -along the eastern shores of Greenland, that commander -crossed over to Spitzbergen, and tried to find the Land of -Gilles. He also accompanied Koldewey’s later expedition, -and shared his belief that there is no continuous channel -northwards on the western side of the North Atlantic channel. -Believing still, however, with Dr. Petermann, the geographer, -that there is an open Polar sea beyond the ice-barrier, Payer -set out in 1871, in company with Weyprecht, towards the -Land of Gilles. They did not find this mysterious land, but -succeeded in passing 150 miles further north, after rounding -the south-eastern shores of Spitzbergen, than any Arctic -voyagers who had before penetrated into the region lying -between Spitzbergen and Novaia Zemlia. Here they found, -beyond the 76th parallel, and between 42° and 60° east -longitude, an open sea, and a temperature of between 5° -and 7° above the freezing-point. Unfortunately, they had -not enough provisions with them to be able safely to travel -further north, and were thus compelled to return. The -season seems to have been an unusually open one; and it -is much to be regretted that the expedition was not better<span class="pagenum"><a id="Page_165">165</a></span> -supplied with provisions—a defect which appears to be -not uncommon with German expeditions.</p> - -<p>Soon after their return, Payer and Weyprecht began to -prepare for a new expedition; and this time their preparations -were thorough, and adapted for a long stay in Arctic -regions. “The chief aim of this expedition,” says the <cite xml:lang="fr" lang="fr">Revue -des Deux Mondes</cite>, in an interesting account of recent Polar -researches, “was to investigate the unknown regions of the -Polar seas to the north of Siberia, and to try to reach -Behring’s Straits by this route.” It was only if after two -winters and three summers they failed to double the extreme -promontory of Asia, that they were to direct their course -towards the Pole. The voyagers, numbering twenty-four -persons, left the Norwegian port of Tromsoë, in the steamer -<i>Tegethoff</i>, on July 14, 1872. Count Wilczek followed shortly -after in a yacht, which was to convey coals and provisions to -an eastern point of the Arctic Ocean, for the benefit of the -<i>Tegethoff</i>. At a point between Novaia Zemlia and the -mouth of the Petschora, the yacht lost sight of the steamer, -and nothing was heard of the latter for twenty-five months. -General anxiety was felt for the fate of the expedition, and -various efforts were made by Austria, England, and Russia -to obtain news of it. In September, 1874, the voyagers -suddenly turned up at another port, and soon after entered -Vienna amid great enthusiasm. Their story was a strange -one.</p> - -<p>It appears that when the <i>Tegethoff</i> was lost sight of -(August 21, 1872), she had been surrounded by vast masses -of ice, which crushed her hull. For nearly half a year the -deadly embrace of the ice continued; and when at length -pressure ceased, the ship remained fixed in the ice, several -miles from open water. During the whole summer the -voyagers tried to release their ship, but in vain. They had -not, however, remained motionless all this time. The yacht -had lost sight of them at a spot between Novaia Zemlia and -Malaia Zemlia (in North Russia) in about 71° north latitude, -and they were imprisoned not far north of this spot. But<span class="pagenum"><a id="Page_166">166</a></span> -the ice-field was driven hither and thither by the winds, -until they found themselves, on the last day of August, 1873, -only 6´ or about seven miles south of the 80th parallel of latitude. -Only fourteen miles from them, on the north, they saw -“a mass of mountainous land, with numerous glaciers.” They -could not reach it until the end of October, however, and then -they had to house themselves in preparation for the long -winter night. This land they called Francis Joseph Land. -It lies north of Novaia Zemlia, and on the Polar side of the -80th parallel of latitude. The winter was stormy and bitterly -cold, the thermometer descending on one occasion to 72° -below zero—very nearly as low as during the greatest cold -experienced by Nares’s party. In February, 1874, “the -sun having reappeared, Lieutenant Payer began to prepare -sledge excursions to ascertain the configuration of the land.... -In the second excursion the voyagers entered Austria -Sound, which bounds Francis Joseph Island on the east and -north, and found themselves, after emerging from it, in the -midst of a large basin, surrounded by several large islands. -The extreme northern point reached by the expedition was -a cape on one of these islands, which they named Prince -Rodolph’s Land, calling the point Cape Fligely. It lies -a little beyond the 81st parallel. They saw land further -north beyond the 83rd degree of latitude, and named it -Petermann’s Land. The archipelago thus discovered is -comparable in extent to that of which Spitzbergen is the -chief island.” The voyagers were compelled now to return, -as the firm ice did not extend further north. They had -a long, difficult, and dangerous journey southwards—sometimes -on open water, in small boats, sometimes on ice, with -sledges—impeded part of the time by contrary winds, and -with starvation staring them in the face during the last -fortnight of their journey. Fortunately, they reached Novaia -Zemlia before their provisions quite failed them, and were -thence conveyed to Wardhoë by a Russian trading ship.</p> - -<p>We have now only to consider the attempts which have -been made to approach the North Pole by the American<span class="pagenum"><a id="Page_167">167</a></span> -route. For, though Collinson in 1850 reached high latitudes -to the north of Behring’s Straits, while Wrangel and -other Russian voyagers have attempted to travel northwards -across the ice which bounds the northern shores of Siberia, -it can hardly be said that either route has been followed -with the definite purpose of reaching the North Pole. I -shall presently, however, have occasion to consider the probable -value of the Behring’s Straits route, which about twelve -years ago was advocated by the Frenchman Lambert.</p> - -<p>Dr. Kane’s expedition in 1853–55 was one of those sent -out in search of Sir John Franklin. It was fitted out at -the expense of the United States Government, and the route -selected was that along Smith’s Sound, the northerly prolongation -of Baffin’s Bay. Kane wintered in 1853 and -1854 in Van Reusselaer’s Inlet, on the western coast of -Greenland, in latitude 78° 43´ north. Leaving his ship, the -<i>Advance</i>, he made a boat-journey to Upernavik, 6° further -south. He next traced Kennedy Channel, the northerly -prolongation of Smith’s Sound, reaching latitude 81° 22´ -north. He named heights visible yet further to the north, -Parry Mountains; and at the time—that is, twenty-two years -ago—the land so named was the highest northerly land yet -seen. Hayes, who had accompanied Kane in this voyage, -succeeded in reaching a still higher latitude in sledges -drawn by Esquimaux dogs. Both Kane and Hayes agreed -in announcing that where the shores of Greenland trend -off eastwards from Kennedy Channel, there is an open -sea, “rolling,” as Captain Maury magniloquently says, “with -the swell of a boundless ocean.” It was in particular -noticed that the tides ebbed and flowed in this sea. On -this circumstance Captain Maury based his conclusion that -there is an open sea to the north of Greenland. After -showing that the tidal wave could not well have travelled -along the narrow and icebound straits between Baffin’s Bay -and the region reached by Kane and Hayes, Maury says: -“Those tides must have been born in that cold sea, having -their cradle about the North Pole.” The context shows,<span class="pagenum"><a id="Page_168">168</a></span> -however, that he really intended to signify that the waves -were formed in seas around the North Pole, and thence -reached the place where they were seen; so that, as birth -usually precedes cradling, Maury would more correctly have -said that these tides are cradled in that cold sea, having their -birth about the North Pole.</p> - -<p>The observations of Kane and Hayes afford no reason, -however, for supposing that there is open water around -the North Pole. They have been rendered somewhat doubtful, -be it remarked in passing, by the results of Captain -Nares’s expedition; and it has been proved beyond -all question that there is not an open sea directly communicating -with the place where Kane and Hayes observed -tidal changes. But, apart from direct evidence of this kind, -two serious errors affect Maury’s reasoning, as I pointed -out eleven years since. In the first place, a tidal wave -would be propagated quite freely along an ice-covered -sea, no matter how thick the ice might be, so long as the -sea was not absolutely icebound. Even if the latter condition -could exist for a time, the tidal wave would burst -the icy fetters that bound the sea, unless the sea were frozen -to the very bottom; which, of course, can never happen -with any sea properly so called. It must be remembered -that, even in the coldest winter of the coldest Polar regions, -ice of only a moderate thickness can form in open sea in -a single day; but the tidal wave does not allow ice to form -for a single hour in such sort as to bind the great ice-fields -and the shore-ice into one mighty mass. At low tide, for a -very short time, ice may form in the spaces between the -shore-ice and the floating ice, and again between the various -masses of floating ice, small or large (up to many square -miles in extent); but as the tidal wave returns it breaks -through these bonds as easily as the Jewish Hercules burst -the withes with which the Philistines had bound his mighty -limbs. It is probable that if solid ice as thick as the -thickest which Nares’s party found floating in the Palæocrystic -Sea—ice 200 feet thick—reached from shore to shore<span class="pagenum"><a id="Page_169">169</a></span> -of the North Atlantic channel, the tidal wave would burst -the barrier as easily as a rivulet rising but a few inches bursts -the thin coating which has formed over it on the first cold -night of autumn. But no such massive barriers have to be -broken through, for the tidal wave never gives the ice an -hour’s rest Maury reasons that “the tidal wave from the -Atlantic can no more pass under the icy barrier to be propagated -in the seas beyond, than the vibrations of a musical -string can pass with its notes a fret on which the musician -has placed his finger.” But the circumstances are totally -different. The ice shares the motion of the tidal wave, -which has not to pass under the ice, but to lift it. This, -of course, it does quite as readily as though there were -no ice, but only the same weight of water. The mere -weight of the ice counts simply for nothing. The tidal wave -would rise as easily in the British Channel if a million Great -Easterns were floating there as if there was not even a -cock-boat; and the weight of ice, no matter how thick or -extensive, would be similarly ineffective to restrain the great -wave which the sun and moon send coursing twice a day -athwart our oceans. Maury’s other mistake was even more -important so far as this question of an open sea is concerned. -“No one,” as I wrote in 1867, “who is familiar -with the astronomical doctrine of the tides, can believe for -a moment that tides could be generated in a land-locked -ocean, so limited in extent as the North Polar sea (assuming -its existence) must necessarily be.” To raise a tidal wave -the sun and moon require not merely an ocean of wide -extent to act upon, but an ocean so placed that there is -a great diversity in their pull on various parts of it; for it -is the difference between the pull exerted on various parts, -and not the pull itself, which creates the tidal wave. Now -the Polar sea has not the required extent, and is not in -the proper position, for this diversity of pull to exist in -sufficient degree to produce a tidal wave which could be -recognized. It is certain, in fact, that, whether there is -open water or not near the Pole, the tides observed by<span class="pagenum"><a id="Page_170">170</a></span> -Kane and Hayes must have come from the Atlantic, and -most probably by the North Atlantic channel.</p> - -<p>Captain Hall’s expedition in the <i>Polaris</i> (really under -the command of Buddington), in 1871–72, will be probably -in the recollection of most of my readers. Leaving Newfoundland -on June 29, 1871, it sailed up Smith’s Sound, -and by the end of August had reached the 80th parallel. -Thence it proceeded up Kennedy Channel, and penetrated -into Robeson Channel, the northerly prolongation -of Kennedy Channel, and only 13 miles wide. Captain -Hall followed this passage as far as 82° 16´ north latitude, -reaching his extreme northerly point on September 3. -From it he saw “a vast expanse of open sea, which he -called Lincoln Sea, and beyond that another ocean or gulf; -while on the west there appeared, as far as the eye could -reach, the contours of coast. This region he called Grant -Land.” So far as appears, there was no reason at that time -why the expedition should not have gone still further north, -the season apparently having been exceptionally open. -But the naval commander of the expedition, Captain Buddington, -does not seem to have had his heart in the work, -and, to the disappointment of Hall, the <i>Polaris</i> returned -to winter in Robeson Channel, a little beyond the 81st -degree. In the same month, September, 1871, Captain -Hall died, under circumstances which suggested to many -of the crew and officers the suspicion that he had been -poisoned.<a id="FNanchor_23" href="#Footnote_23" class="fnanchor">23</a> In the spring of 1870 the <i>Polaris</i> resumed -her course homewards. They were greatly impeded by the -ice. A party which got separated from those on board -were unfortunately unable to regain the ship, and remained -on an ice-field for 240 days, suffering fearfully. The ice-field, -like that on which the crew of the <i>Hansa</i> had to -take up their abode, drifted southwards, and was gradually -diminishing, when fortunately a passing steamer observed<span class="pagenum"><a id="Page_171">171</a></span> -the prisoners (April 30, 1872) and rescued them. The -<i>Polaris</i> herself was so injured by the ice that her crew had -to leave her, wintering on Lyttelton Island. They left this -spot in the early summer of 1872, in two boats, and were -eventually picked up by a Scotch whaler.</p> - -<p>Captain Nares’s expedition followed Hall’s route. I -do not propose to enter here into any of the details of the -voyage, with which my readers are no doubt familiar. -The general history of the expedition must be sketched, -however, in order to bring it duly into its place here. -The <i>Alert</i> and <i>Discovery</i> sailed under Captains Nares and -Stephenson, in May, 1875. Their struggle with the ice -did not fairly commence until they were nearing the 79th -parallel, where Baffin’s Bay merges into Smith’s Sound. -Thence, through Smith’s Sound, Kennedy Channel, and -Robeson Channel, they had a constant and sometimes -almost desperate struggle with the ice, until they had -reached the north end of Robeson Channel. Here the -<i>Discovery</i> took up her winter quarters, in north latitude -81° 44´, a few miles north of Captain Hall’s wintering-place, -but on the opposite (or westerly) side of Robeson Channel. -The <i>Alert</i> still struggled northwards, rounding the north-east -point of Grant Land, and there finding, not, as was -expected, a continuous coast-line on the west, but a vast -icebound sea. No harbour could be found, and the ship -was secured on the inside of a barrier of grounded ice, -in latitude 82° 31´, in the most northerly wintering-place -ever yet occupied by man. The ice met with on this sea -is described as “of most unusual age and thickness, resembling -in a marked degree, both in appearance and -formation, low floating icebergs rather than ordinary salt-water -ice. Whereas ordinary ice is from 2 feet to 10 feet -in thickness, that in this Polar sea has gradually increased -in age and thickness until it measures from 80 feet to 120 -feet, floating with its surface at the lower part 15 feet above -the water-line. In some places the ice reaches a thickness -of from 150 to 200 feet, and the general impression among<span class="pagenum"><a id="Page_172">172</a></span> -the officers of the expedition seems to have been that the -ice of this Palæocrystic Sea is the accumulation of many -years, if not of centuries; “that the sea is never free of -it and never open; and that progress to the Pole through -it or over it is impossible with our present resources.”</p> - -<p>The winter which followed was the bitterest ever known -by man. For 142 days the sun was not seen; the mercury -was frozen during nearly nine weeks. On one occasion the -thermometer showed 104° below the freezing-point, and -during one terrible fortnight the mean temperature was 91° -below freezing!</p> - -<p>As soon as the sun reappeared sledge-exploration began, -each ship being left with only half-a-dozen men and officers -on board. Expeditions were sent east and west, one to -explore the northern coast of Greenland, the other to -explore the coast of Grant Land. Captain Stephenson -crossed over from the <i>Discovery’s</i> wintering-place to Polaris -Bay, and there placed over Hall’s grave a tablet, prepared -in England, bearing the following inscription: “Sacred -to the memory of Captain C. F. Hall, of U.S. <i>Polaris</i>, -who sacrificed his life in the advancement of science, on -November 8, 1871. This tablet has been erected by the -British Polar Expedition of 1875, who, following in his -footsteps, have profited by his experience”—a graceful -acknowledgment (which might, however, have been better -expressed). The party which travelled westwards traced -the shores of Grant Land as far as west longitude 86° 30´, -the most northerly cape being in latitude 83° 7´, and longitude -70° 30´ west. This cape they named Cape Columbia.</p> - -<p>The coast of Greenland was explored as far east as -longitude 50° 40´ (west), land being seen as far as 82° 54´ -north, longitude 48° 33´ west. Lastly, a party under Commander -Markham and Lieutenant Parr pushed northwards. -They were absent ten weeks, but had not travelled so far -north in the time as was expected, having encountered -great difficulties. On May 12, 1876, they reached their -most northerly point, planting the British flag in latitude<span class="pagenum"><a id="Page_173">173</a></span> -83° 20´ 26´´ north. “Owing to the extraordinary nature of -the pressed-up ice, a roadway had to be formed by pickaxes -for nearly half the distance travelled, before any advance -could be safely made, even with light loads; this rendered -it always necessary to drag the sledge-loads forward by -instalments, and therefore to journey over the same road -several times. The advance was consequently very slow, -and only averaged about a mile and a quarter daily—much -the same rate as was attained by Sir Edward Parry during -the summer of 1827. The greatest journey made in any one -day amounted only to two miles and three quarters. Although -the distance made good was only 73 miles from the ship, 276 -miles were travelled over to accomplish it.” It is justly -remarked, in the narrative from which I have made this -extract, that no body of men could have surpassed in praiseworthy -perseverance this gallant party, whose arduous -struggle over the roughest and most monotonous road -imaginable, may fairly be regarded as surpassing all former -exploits of the kind. (The narrator says that it has -“eclipsed” all former ones, which can scarcely be intended -to be taken <i xml:lang="fr" lang="fr">au pied de la lettre</i>.) The expedition reached -the highest latitude ever yet attained under any conditions, -carried a ship to higher latitudes than any ship had before -reached, and wintered in higher latitudes than had -ever before been dwelt in during the darkness of a Polar -winter. They explored the most northerly coast-line yet -traversed, and this both on the east and west of their route -northwards. They have ascertained the limits of human -habitation upon this earth, and have even passed beyond the -regions which animals occupy, though nearly to the most -northerly limit of the voyage they found signs of the -occasional visits of warm-blooded animals. Last, but not -least, they have demonstrated, as it appears to me (though -possibly Americans will adopt a different opinion), that by -whatever route the Pole is to be reached, it is not by that -which I have here called the American route, at least with -the present means of transit over icebound seas. The<span class="pagenum"><a id="Page_174">174</a></span> -country may well be satisfied with such results (apart -altogether from the scientific observations, which are the best -fruits of the expedition), even though the Pole has not yet -been reached.</p> - -<p>Must we conclude, however, that the North Pole is -really inaccessible? It appears to me that the annals of -Arctic research justify no such conclusion. The attempt -which has just been made, although supposed at the outset -to have been directed along the most promising of all the -routes heretofore tried, turned out to be one of the most -difficult and dangerous. Had there been land extending -northwards (as Sherard Osborn and others opined), on the -western side of the sea into which Robeson Channel opens, -a successful advance might have been made along its shore -by sledging. M’Clintock, in 1853, travelled 1220 miles in -105 days; Richards 1012 miles in 102 days; Mecham -1203 miles; Richards and Osborn 1093 miles; Hamilton -1150 miles with a dog-sledge and one man. In 1854 Mecham -travelled 1157 miles in only 70 days; Young travelled -1150 miles and M’Clintock 1330 miles. But these journeys -were made either over land or over unmoving ice close to a -shore-line. Over an icebound sea journeys of the kind are -quite impracticable. But the conditions, while not more -favourable in respect of the existence of land, were in other -respects altogether less favourable along the American route -than along any of the others I have considered in this brief -sketch of the attempts hitherto made to reach the Pole.</p> - -<p>The recent expedition wintered as near as possible to the -region of maximum winter cold in the western hemisphere, -and pushed their journey northwards athwart the region of -maximum summer cold. Along the course pursued by -Parry’s route the cold is far less intense, in corresponding -latitudes, than along the American route; and cold is the -real enemy which bars the way towards the Pole. All the -difficulties and dangers of the journey either have their -origin (as directly as the ice itself) in the bitter Arctic cold, -or are rendered effective and intensified by the cold. The<span class="pagenum"><a id="Page_175">175</a></span> -course to be pursued, therefore, is that indicated by the -temperature. Where the July isotherms, or lines of equal -summer heat, run northwards, a weak place is indicated in -the Arctic barrier; where they trend southwards, that barrier -is strongest. Now there are two longitudes in which the -July Arctic isotherms run far northward of their average -latitude. One passes through the Parry Islands, and -indicates the sea north-east of Behring’s Straits as a suitable -region for attack; the other passes through Spitzbergen, and -indicates the course along which Sir E. Parry’s attack was -made. The latter is slightly the more promising line of the -two, so far as temperature is concerned, the isotherm of 36° -Fahrenheit (in July) running here as far north as the 77th -parallel, whereas its highest northerly range in the longitude -of the Parry Islands is but about 76°. The difference, however, -is neither great nor altogether certain; and the fact -that Parry found the ice drifting southwards, suggests the -possibility that that <em>may</em> be the usual course of oceanic -currents in that region. North of the Parry Islands the drift -may be northwardly, like that which Payer and Weyprecht -experienced to the north of Novaia Zemlia.</p> - -<p>There is one great attraction for men of science in the -route by the Parry Islands. The magnetic pole has almost -certainly travelled into that region. Sir J. Ross found it, -indeed, to be near Boothia Gulf, far to the east of the -Parry Islands, in 1837. But the variations of the needle all -over the world since then, indicate unmistakably that the -magnetic poles have been travelling round towards the west, -and at such a rate that the northern magnetic pole has probably -nearly reached by this time the longitude of Behring’s -Straits. The determination of the exact present position of -the Pole would be a much more important achievement, so -far as science is concerned, than a voyage to the pole of -rotation.</p> - -<p>There is one point which suggests itself very forcibly -in reading the account of the sledging expedition from the -<i>Alert</i> towards the north. In his official report, Captain<span class="pagenum"><a id="Page_176">176</a></span> -Nares says that “half of each day was spent in dragging -the sledges in that painful fashion—face toward the boat—in -which the sailors drag a boat from the sea on to the -sand;” and again he speaks of the “toilsome dragging of -the sledges over ice-ridges which resembled a stormy sea -suddenly frozen.” In doing this “276 miles were toiled -over in travelling only 73 miles.” Is it altogether clear -that the sledges were worth the trouble? One usually regards -a sledge as intended to carry travellers and their -provisions, etc., over ice and snow, and as useful when so -employed; but when the travellers have to take along the -sledge, going four times as far and working ten times as -hard as if they were without it, the question suggests itself -whether all necessary shelter, provisions, and utensils might -not have been much more readily conveyed by using a -much smaller and lighter sledge, and by distributing a large -part of the luggage among the members of the expedition. -The parts of a small hut could, with a little ingenuity, be -so constructed as to admit of being used as levers, crowbars, -carrying-poles, and so forth, and a large portion of the -luggage absolutely necessary for the expedition could be -carried by their help; while a small, light sledge for the -rest could be helped along and occasionally lifted bodily -over obstructions by levers and beams forming part of the -very material which by the usual arrangement forms part -of the load. I am not suggesting, be it noticed, that by -any devices of this sort a journey over the rough ice of -Arctic regions could be made easy. But it does seem to me -that if a party could go back and forth over 276 miles, -pickaxing a way for a sledge, and eventually dragging it -along over the path thus pioneered for it, and making only -an average of 1¼ mile of real progress per day, or 73 miles -in all, the same men could with less labour (though still, -doubtless, with great toil and trouble) make six or seven -miles a day by reducing their <i xml:lang="la" lang="la">impedimenta</i> to what could -be carried directly along with them. Whether use might not -be made of the lifting power of buoyant gas, is a question<span class="pagenum"><a id="Page_177">177</a></span> -which only experienced aëronauts and Arctic voyagers could -answer. I believe that the employment of imprisoned -balloon-power for many purposes, especially in time of war, -has received as yet much less attention than it deserves. -Of course I am aware that in Arctic regions many difficulties -would present themselves; and the idea of ordinary -ballooning over the Arctic ice-fields may be regarded as -altogether wild in the present condition of the science of -aëronautics. But the use of balloon-power as an auxiliary, -however impracticable at present, is by no means to be -despaired of as science advances.</p> - -<p>After all, however, the advance upon the Pole itself, -however interesting to the general public, is far less important -to science than other objects which Arctic travellers -have had in view. The inquiry into the phenomena of -terrestrial magnetism within the Arctic regions; the investigation -of oceanic movements there; of the laws according -to which low temperatures are related to latitude and -geographical conditions; the study of aerial phenomena; -of the limits of plant life and animal life; the examination -of the mysterious phenomena of the Aurora Borealis—these -and many other interesting subjects of investigation have -been as yet but incompletely dealt with. In the Polar -regions, as Maury well remarked, “the icebergs are framed -and glaciers launched; there the tides have their cradle, -the whales their nursery; there the winds complete their -circuit, and the currents of the sea their round, in the wonderful -system of oceanic circulation; there the Aurora is -lighted up, and the trembling needle brought to rest; and -there, too, in the mazes of that mystic circle, terrestrial -forces of occult power and of vast influence upon the well-being -of man are continually at work. It is a circle of -mysteries; and the desire to enter it, to explore its untrodden -wastes and secret chambers, and to study its -physical aspects, has grown into a longing. Noble daring -has made Arctic ice and snow-clad seas classic ground.”</p> - -<hr /> - -<p><span class="pagenum"><a id="Page_178">178</a></span></p> - -<div class="chapter"> -<h2><a id="A_MIGHTY_SEA-WAVE"></a><i>A MIGHTY SEA-WAVE.</i></h2> -</div> - -<p class="in0">On May 10th, 1876, a tremendous wave swept the Pacific -Ocean from Peru northwards, westwards, and southwards, -travelling at a rate many times greater than that of the -swiftest express train. For reasons best known to themselves, -writers in the newspapers have by almost common -consent called this phenomenon a tidal-wave. But the -tides had nothing to do with it. Unquestionably the -wave resulted from the upheaval of the bed of the ocean -in some part of that angle of the Pacific Ocean which is -bounded by the shores of Peru and Chili. This region -has long been celebrated for tremendous submarine and -subterranean upheavals. The opinions of geologists and -geographers have been divided as to the real origin of the -disturbances by which at one time the land, at another -time the sea, and at yet other times (oftener, in fact, than -either of the others) both land and sea have been shaken -as by some mighty imprisoned giant, struggling, like -Prometheus, to cast from his limbs the mountain masses -which hold them down. Some consider that the seat of -the Vulcanian forces lies deep below that part of the chain -of the Andes which lies at the apex of the angle just -mentioned, and that the direction of their action varies -according to the varying conditions under which the imprisoned -gases find vent. Others consider that there are -two if not several seats of subterranean activity. Yet -others suppose that the real seat of disturbance lies beneath<span class="pagenum"><a id="Page_179">179</a></span> -the ocean itself, a view which seems to find support in -several phenomena of recent Peruvian earthquakes.</p> - -<p>Although we have not full information concerning the -great wave which in May, 1876, swept across the Pacific, -and northwards and southwards along the shores of the -two Americas, it may be interesting to consider some of -the more striking features of this great disturbance of the -so-called peaceful ocean, and to compare them with those -which have characterized former disturbances of a similar -kind. We may thus, perhaps, find some evidence by which -an opinion may be formed as to the real seat of subterranean -activity in this region.</p> - -<p>At the outset it may be necessary to explain why I -have asserted somewhat confidently that the tides have -nothing whatever to do with this great oceanic wave. It -is of course well known to every reader that the highest -or spring tides occur always two or three days after new -moon and after full moon, the lowest (or rather the tides -having least range above and below the mean level) occurring -two or three days after the first and third quarters of -the lunar month. The sun and moon combine, indeed, -to sway the ocean most strongly at full and new, while they -pull contrariwise at the first and third quarters; but the -full effect of their combined effort is only felt a few days -later than when it is made, while the full effect of their -opposition to each other, in diminishing the range of the -oceanic oscillation, is also only felt after two or three -days. Thus in May, 1876, the tidal wave had its greatest -range on or about May 16, new moon occurring at half-past -five on the morning of May 13; and the tidal wave -had its least range on or about May 8, the moon passing -her third quarter a little after eleven on the morning of -May 4. Accordingly the disturbance which affected the -waters of the Pacific so mightily on May 10, occurred two -days after the lowest or neap tides, and five days before -the highest or spring tides. Manifestly that was not a time -when a tidal wave of exceptional height could be expected,<span class="pagenum"><a id="Page_180">180</a></span> -or, indeed, could possibly occur. Such a wave as actually -disturbed the Pacific on that day could not in any case -have been produced by tidal action, even though the winds -had assisted to their utmost, and all the circumstances -which help to make high tides had combined—as the -greatest proximity of moon to earth, the conjunction of -moon and sun near the celestial equator, and (of course) -the exact coincidence of the time of the tidal disturbance -with that when the combined pull of the sun and moon is -strongest. As, instead, the sun was nearly eighteen degrees -from the equator, the moon more than nine, and as the -moon was a full week’s motion from the part of her path -where she is nearest to the earth, while, as we have seen, -only two days had passed from the time of absolutely lowest -tides, it will be seen how utterly unable the tidal-wave -must have been on the day of the great disturbance to produce -the effects presently to be described.</p> - -<p>It may seem strange, in dealing with the case of a wave -which apparently had its origin in or near Peru on May 9, -to consider the behaviour of a volcano, distant 5000 miles -from this region, a week before the disturbance took place. -But although the coincidence may possibly have been -accidental, yet in endeavouring to ascertain the true seat of -disturbance we must overlook no evidence, however seemingly -remote, which may throw light on that point; and -as the sea-wave generated by the disturbance reached very -quickly the distant region referred to, it is by no means -unlikely that the subterranean excitement which the disturbance -relieved may have manifested its effects beforehand -at the same remote volcanic region. Be this as it -may, it is certain that on May 1 the great crater of Kilauea, -in the island of Hawaii, became active, and on the 4th -severe shocks of earthquake were felt at the Volcano -House. At three in the afternoon a jet of lava was thrown -up to a height of about 100 feet, and afterwards some fifty -jets came into action. Subsequently jets of steam issued -along the line formed by a fissure four miles in length<span class="pagenum"><a id="Page_181">181</a></span> -down the mountain-side. The disturbance lessened considerably -on the 5th, and an observing party examined the -crater. They found that a rounded hill, 700 feet in height, -and 1400 feet in diameter, had been thrown up on the -plain which forms the floor of the crater. Fire and scoria -spouted up in various places.</p> - -<p>Before rejecting utterly the belief that the activity thus -exhibited in the Hawaii volcano had its origin in the same -subterrene or submarine region as the Peruvian earthquake, -we should remember that other regions scarcely less remote -have been regarded as forming part of the same Vulcanian -district. The violent earthquakes which occurred at New -Madrid, in Missouri, in 1812, took place at the same time -as the earthquake of Caraccas, the West Indian volcanoes -being simultaneously active; and earthquakes had been -felt in South Carolina for several months before the destruction -of Caraccas and La Guayra. Now we have abundant -evidence to show that the West Indian volcanoes are -connected with the Peruvian and Chilian regions of Vulcanian -energy, and the Chilian region is about as far from -New Madrid as Arica in Peru from the Sandwich Isles.</p> - -<p>It was not, however, until about half-past eight on the -evening of May 9 that the Peruvian earthquake began. A -severe shock, lasting from four to five minutes, was felt -along the entire southern coast, even reaching Antofagasta. -The shock was so severe that it was impossible, in many -places, to stand upright. It was succeeded by several others -of less intensity.</p> - -<p>While the land was thus disturbed, the sea was observed -to be gradually receding, a movement which former experiences -have taught the Peruvians to regard with even -more terror than the disturbance of the earth itself. The -waters which had thus withdrawn, as if concentrating their -energies to leap more fiercely on their prey, presently -returned in a mighty wave, which swept past Callao, travelling -southwards with fearful velocity, while in its train -followed wave after wave, until no less than eight had taken<span class="pagenum"><a id="Page_182">182</a></span> -their part in the work of destruction. At Mollendo the -railway was torn up by the sea for a distance of 300 feet. -A violent hurricane which set in afterwards from the south -prevented all vessels from approaching, and unroofed most -of the houses in the town. At Arica the people were busily -engaged in preparing temporary fortifications to repel a -threatened assault of the rebel ram <i>Huiscar</i>, at the moment -when the roar of the earthquake was heard. The shocks -here were very numerous, and caused immense damage in -the town, the people flying to the Morro for safety. The -sea was suddenly perceived to recede from the beach, and -a wave from ten feet to fifteen feet in height rolled in upon -the shore, carrying before it all that it met. Eight times was -this assault of the ocean repeated. The earthquake had -levelled to the ground a portion of the custom-house, the -railway station, the submarine cable office, the hotel, the -British Consulate, the steamship agency, and many private -dwellings. Owing to the early hour of the evening, and -the excitement attendant on the proposed attack of the -<i>Huiscar</i>, every one was out and stirring; but the only loss of -life which was reported was that of three little children who -were overtaken by the water. The progress of the wave -was only stopped at the foot of the hill on which the church -stands, which point is further inland than that reached in -August, 1868. Four miles of the embankment of the railway -were swept away like sand before the wind. Locomotives, -cars, and rails, were hurled about by the sea like -so many playthings, and left in a tumbled mass of rubbish.</p> - -<p>The account proceeds to say that the United States -steamer <i>Waters</i>, stranded by the bore of 1868, was lifted -up bodily by the wave at Arica, and floated two miles north -of her former position. The reference is no doubt to the -double-ender <i>Watertree</i>, not stranded by a bore (a term -utterly inapplicable to any kind of sea-wave at Arica, where -there is no large river), but carried in by the great wave -which followed the earthquake of August 13. The description -of the wave at Arica on that occasion should be<span class="pagenum"><a id="Page_183">183</a></span> -compared with that of the wave of May, 1876. About twenty -minutes after the first earth shock, the sea was seen to retire, -as if about to leave the shores wholly dry; but presently -its waters returned with tremendous force. A mighty wave, -whose length seemed immeasurable, was seen advancing -like a dark wall upon the unfortunate town, a large part -of which was overwhelmed by it. Two ships, the Peruvian -corvette <i>America</i>, and the American double-ender <i>Watertree</i>, -were carried nearly half a mile to the north of Arica, -beyond the railroad which runs to Tacna, and there left -stranded high and dry. As the English vice-consul at Arica -estimated the height of this enormous wave at fully fifty -feet, it would not seem that the account of the wave of May, -1876, has been exaggerated, for a much less height is, as -we have seen, attributed to it, though, as it carried the -<i>Watertree</i> still further inland, it must have been higher. -The small loss of life can be easily understood when we -consider that the earthquake was not followed instantly by -the sea-wave. Warned by the experience of the earthquake -of 1868, which most of them must have remembered, the -inhabitants sought safety on the higher grounds until the -great wave and its successors had flowed in. We read that -the damage done was greater than that caused by the previous -calamity, the new buildings erected since 1868 being -of a more costly and substantial class. Merchandise from -the custom-house and stores was carried by the water to a -point on the beach five miles distant.</p> - -<p>At Iquique, in 1868, the great wave was estimated at -fifty feet in height. We are told that it was black with -the mud and slime of the sea bottom. “Those who witnessed -its progress from the upper balconies of their houses, -and presently saw its black mass rushing close beneath their -feet, looked on their safety as a miracle. Many buildings -were, indeed, washed away, and in the low-lying parts of -the town there was a terrible loss of life.” In May, 1876, -the greatest mischief at Iquique would seem to have been -caused by the earthquake, not by the sea-wave, though<span class="pagenum"><a id="Page_184">184</a></span> -this also was destructive in its own way. “Iquique,” we -are told, “is in ruins. The movement was experienced -there at the same time and with the same force [as at -Arica]. Its duration was exactly four minutes and a third. -It proceeded from the south-east, exactly from the direction -of Ilaga.” The houses built of wood and cane tumbled down -at the first attacks, lamps were broken, and the burning oil -spread over and set fire to the ruins. Three companies of -firemen, German, Italian, and Peruvian, were instantly at -their posts, although it was difficult to maintain an upright -position, shock following shock with dreadful rapidity. -Nearly 400,000 quintals of nitrate in the stores at Iquique -and the adjacent ports of Molle and Pisagua were destroyed. -The British barque <i>Caprera</i> and a German barque sank, and -all the coasting craft and small boats in the harbour were -broken to pieces and drifted about in every direction.</p> - -<p>At Chanavaya, a small town at the guano-loading dépôt -known as Pabellon de Pica, only two houses were left -standing out of four hundred. Here the earthquake shock -was specially severe. In some places the earth opened in -crevices seventeen yards deep and the whole surface of the -ground was changed.</p> - -<p>At Punta de Eobos two vessels were lost, and fourteen -ships more or less damaged, by the wave. Antofagasta, Mexillones, -Tocopilla, and Cobigo, on the Bolivian coast, suffered -simultaneously from the earthquake and the sea-wave. The -sea completely swept the business portion of Antofagasta -during four hours. Here a singular phenomenon was -noticed. For some time the atmosphere was illuminated -with a ruddy glow. It was supposed that this light came -from the volcano of San Pedro de Atacama, a few leagues -inland from Antofagasta. A somewhat similar phenomenon -was noticed at Tacna during the earthquake of August, 1868. -About three hours after the earthquake an intensely brilliant -light made its appearance above the neighbouring mountains. -It lasted fully half an hour, and was ascribed to the eruption -of some as yet unknown volcano.</p> - -<p><span class="pagenum"><a id="Page_185">185</a></span> -As to the height of the great wave along this part of the -shore-line of South America, the accounts vary. According -to those which are best authenticated, it would seem as -though the wave exceeded considerably in height that which -flowed along the Peruvian, Bolivian, and Chilian shores in -August, 1868. At Huaniles the wave was estimated at sixty -feet in height, at Mexillones, where the wave, as it passed -southwards, ran into Mexillones Bay, it reached a height of -sixty-five feet. Two-thirds of the town were completely -obliterated, wharves, railway stations, distilleries, etc., all -swallowed up by the sea.</p> - -<p>The shipping along the Peruvian and Bolivian coast -suffered terribly. The list of vessels lost or badly injured at -Pabellon de Pica alone, reads like the list of a fleet.</p> - -<p>I have been particular in thus describing the effects -produced by the earthquake and sea-wave on the shores of -South America, in order that the reader may recognize in -the disturbance produced there the real origin of the great -wave which a few hours later reached the Sandwich Isles, -5000 miles away. Doubt has been entertained respecting -the possibility of a wave, other than the tidal-wave, being -transmitted right across the Pacific. Although in August, -1868, the course of the great wave which swept from -some region near Peru, not only across the Pacific, but in -all directions over the entire ocean, could be clearly traced, -there were some who considered the connection between the -oceanic phenomena and the Peruvian earthquake a mere -coincidence. It is on this account perhaps chiefly that the -evidence obtained in May, 1876, is most important. It is -interesting, indeed, as showing how tremendous was the disturbance -which the earth’s frame must then have undergone. -It would have been possible, however, had we no other -evidence, for some to have maintained that the wave which -came in upon the shores of the Sandwich Isles a few hours -after the earthquake and sea disturbance in South America -was in reality an entirely independent phenomenon. But -when we compare the events which happened in May, 1876,<span class="pagenum"><a id="Page_186">186</a></span> -with those of August, 1868, and perceive their exact similarity, -we can no longer reasonably entertain any doubt of the -really stupendous fact that <em>the throes of the earth in and near -Peru are of sufficient energy to send oceanic waves right across -the Pacific</em>,—waves, too, of such enormous height at starting, -that, after travelling with necessarily diminishing height the -whole way to Hawaii, they still rose and fell through thirty-six -feet The real significance of this amazing oceanic disturbance -is exemplified by the wave circles which spread around -the spot where a stone has fallen into a smooth lake. We -know how, as the circles widen, the height of the wave grows -less and less, until, at no great distance from the centre of -disturbance, the wave can no longer be discerned, so slight -is the slope of its advancing and following faces. How -tremendous, then, must have been the upheaval of the bed -of ocean by which wave-circles were sent across the Pacific, -retaining, after travelling 5000 miles from the centre of disturbance, -the height of a two-storied house! In 1868, indeed, -we know that the wave travelled very much further, reaching -the shores of Japan, of New Zealand, and of Australia, even -if it did not make its way through the East Indian Archipelago -to the Indian Ocean, as some observations seem to -show. Although no news has been received which would -justify us in believing that the wave of May, 1876, produced -corresponding effects at such great distances from the centre -of disturbance, it must be remembered that the dimensions -of the wave when it reached the Sandwich Isles fell far -short of those of the great wave of August 13–14, 1868.</p> - -<p>It will be well to make a direct comparison between the -waves of May, 1876, and August, 1868, in this respect, as -also with regard to the rate at which they would seem to have -traversed the distance between Peru and Hawaii. On this -last point, however, it must be noted that we cannot form an -exact opinion until we have ascertained the real region of -Vulcanian disturbance on each occasion. It is possible that -a careful comparison of times, and of the direction in which -the wave front advanced upon different shores, might serve<span class="pagenum"><a id="Page_187">187</a></span> -to show where this region lay. I should not be greatly -surprised to learn that it was far from the continent of South -America.</p> - -<p>The great wave reached the Sandwich Isles between four -and five on the morning of May 10, corresponding to about -five hours later of Peruvian time. An oscillation only was -first observed at Hilo, on the east coast of the great southern -island of Hawaii, the wave itself not reaching the village till -about a quarter before five. The greatest difference between -the crest and trough of the wave was found to be thirty-six -feet here; but at the opposite side of the island, in Kealakekua -Bay (where Captain Cook was killed), amounted only -to thirty feet. In other places the difference was much less, -being in some only three feet, a circumstance doubtless due -to interference, waves which have reached the same spot -along different courses chancing so to arrive that the crest of -one corresponded with the trough of the other, so that the -resulting wave was only the difference of the two. We must -explain, however, in the same way, the highest waves of -thirty-six to forty feet, which were doubtless due to similar -interference, crest agreeing with crest and trough with trough, -so that the resulting wave was the sum of the two which had -been divided, and had reached the same spot along different -courses. It would follow that the higher of the two waves -was about twenty-one feet high, the lower about eighteen -feet high; but as some height would be lost in the encounter -with the shore-line, wherever it lay, on which the waves -divided, we may fairly assume that in the open ocean, before -reaching the Sandwich group, the wave had a height of -nearly thirty feet from trough to crest. We read, in accordance -with this explanation, that “the regurgitations of the -sea were violent and complex, and continued through the -day.”</p> - -<p>The wave, regarded as a whole, seems to have reached -all the islands at the same time. Since this has not been -contradicted by later accounts, we are compelled to conclude -that the wave reached the group with its front parallel to the<span class="pagenum"><a id="Page_188">188</a></span> -length of the group, so that it must have come (arriving as it -did from the side towards which Hilo lies) from the north-east -It was, then, not the direct wave from Peru, but the -wave reflected from the shores of California, which produced -the most marked effects. We can understand well, this being -so, that the regurgitations of the sea were complex. Any -one who has watched the inflow of waves on a beach so -lying within an angle of the line that while one set of waves -comes straight in from the sea, another thwart set comes -from the shore forming the other side of the angle, will -understand how such waves differ from a set of ordinary -rollers. The crests of the two sets form a sort of network, -ever changing as each set rolls on; and considering any one -of the four-cornered meshes of this wave-net, the observer -will notice that while the middle of the raised sides rises -little above the surrounding level, because here the crests of -one set cross the troughs of the other, the corners of each -quadrangle are higher than they would be in either set taken -separately, while the middle of the four-cornered space is -correspondingly depressed. The reason is that at the -corners of the wave-net crests join with crests to raise the -water surface, while in the middle of the net (not the middle -of the sides, but the middle of the space enclosed by the -four sides) trough joins with trough to depress the water -surface.<a id="FNanchor_24" href="#Footnote_24" class="fnanchor">24</a></p> - -<p>We must take into account the circumstance that the wave -which reached Hawaii in May, 1876, was probably reflected -from the Californian coast, when we endeavour to determine -the rate at which the sea disturbance was propagated across<span class="pagenum"><a id="Page_189">189</a></span> -the Atlantic. The direct wave would have come sooner, -and may have escaped notice because arriving in the night-time, -as it would necessarily have done if a wave which -travelled to California, and thence, after reflection, to the -Sandwich group arrived there at a quarter before five in the -morning following the Peruvian earthquake. We shall be -better able to form an opinion on this point after considering -what happened in August, 1868.</p> - -<p>The earth-throe on that occasion was felt in Peru about -five minutes past five on the evening of August 13. Twelve -hours later, or shortly before midnight, August 13, Sandwich -Island time (corresponding to 5 p.m., August 14, Peruvian -time), the sea round the group of the Sandwich Isles rose in -a surprising manner, “insomuch that many thought the -islands were sinking, and would shortly subside altogether -beneath the waves. Some of the smaller islands were for a -time completely submerged. Before long, however, the sea -fell again, and as it did so the observers found it impossible -to resist the impression that the islands were rising bodily -out of the water. For no less than three days this strange -oscillation of the sea continued to be experienced, the most -remarkable ebbs and floods being noticed at Honolulu, on -the island of Woahoo.”</p> - -<p>The distance between Honolulu and Arica is about 6300 -statute miles; so that, if the wave travelled directly from the -shores of Peru to the Sandwich Isles, it must have advanced -at an average rate of about 525 miles an hour (about 450 -knots an hour). This is nearly half the rate at which the -earth’s surface near the equator is carried round by the -earth’s rotation, or is about the rate at which parts in latitude -62 or 63 degrees north are carried round by rotation; so -that the motion of the great wave in 1868 was fairly comparable -with one of the movements which we are accustomed -to regard as cosmical. I shall presently have something -more to say on this point.</p> - -<p>Now in May, 1876, as we have seen, the wave reached -Hawaii at about a quarter to five in the morning, corresponding<span class="pagenum"><a id="Page_190">190</a></span> -to about ten, Peruvian time. Since, then, the earthquake -was felt in Peru at half-past eight on the previous evening, -it follows that the wave, if it travelled directly from Peru, -must have taken about 13½ hours—or an hour and a half -longer, in travelling from Peru to the Sandwich Isles, than -it took in August, 1868. This is unlikely, because ocean-waves -travel nearly at the same rate in the same parts of the -ocean, whatever their dimensions, so only that they are large. -We have, then, in the difference of time occupied by the -wave in May, 1876, and in August, 1868, in reaching Hawaii, -some confirmation of the result to which we were led by the -arrival of the wave simultaneously at all the islands of the -Sandwich group—the inference, namely, that the observed -wave had reached these islands after reflection from the -Californian shore-line. As the hour when the direct wave -probably reached Hawaii was about a quarter past three in -the morning, when not only was it night-time but also a -time when few would be awake to notice the rise and fall of -the sea, it seems not at all improbable that the direct wave -escaped notice, and that the wave actually observed was the -reflected wave from California. The direction, also, in which -the oscillation was first observed corresponds well with this -explanation.</p> - -<p>It is clear that the wave which traversed the Pacific in -May, 1876, was somewhat inferior in size to that of August, -1868, which therefore still deserves to be called (as I then -called it) the greatest sea-wave ever known. The earthquake, -indeed, which preceded the oceanic disturbance of -1868 was far more destructive than that of May, 1876, and -the waves which came in upon the Peruvian and Bolivian -shores were larger. Nevertheless, the wave of May, 1876, -was not so far inferior to that of August, 1868, but that its -course could be traced athwart the entire extent of the -Pacific Ocean.</p> - -<p>When we consider the characteristic features of the -Peruvian and Chilian earthquakes, and especially when we -note how wide is the extent of the region over which their<span class="pagenum"><a id="Page_191">191</a></span> -action is felt in one way or another, it can scarcely be -doubted that the earth’s Vulcanian energies are at present -more actively at work throughout that region than in any -other. There is nothing so remarkable, one may even say -so stupendous, in the history of subterranean disturbance as -the alternation of mighty earth-throes by which, at one time, -the whole of the Chilian Andes seem disturbed and anon -the whole of the Peruvian Andes. In Chili scarcely a year -ever passes without earthquakes, and the same may be said -of Peru; but so far as great earthquakes are concerned the -activity of the Peruvian region seems to synchronize with the -comparative quiescence of the Chilian region, and <i xml:lang="la" lang="la">vice versâ</i>. -Thus, in 1797, the terrible earthquake occurred which is -known as the earthquake of Riobamba, which affected the -entire Peruvian earthquake region. Thirty years later a -series of tremendous throes shook the whole of Chili, permanently -elevating its long line of coast to the height of -several feet. During the last twelve years the Peruvian region -has in turn been disturbed by great earthquakes. It should -be added that between Chili and Peru there is a region about -five hundred miles in length in which scarcely any volcanic -action has been observed. And singularly enough, “this -very portion of the Andes, to which one would imagine that -the Peruvians and Chilians would fly as to a region of safety, -is the part most thinly inhabited; insomuch that, as Von -Buch observes, it is in some places entirely deserted.”</p> - -<p>One can readily understand that this enormous double -region of earthquakes, whose oscillations on either side of -the central region of comparative rest may be compared to -the swaying of a mighty see-saw on either side of its point -of support, should be capable of giving birth to throes propelling -sea-waves across the Pacific Ocean. The throe -actually experienced at any given place is relatively but an -insignificant phenomenon: it is the disturbance of the entire -region over which the throe is felt which must be considered -in attempting to estimate the energy of the disturbing cause. -The region shaken by the earthquake of 1868, for instance,<span class="pagenum"><a id="Page_192">192</a></span> -was equal to at least a fourth of Europe, and probably to -fully one-half. From Quito southwards as far as Iquique—or -along a full third part of the length of the South American -Andes—the shock produced destructive effects. It was also -distinctly felt far to the north of Quito, far to the south of -Iquique, and inland to enormous distances. The disturbing -forces which thus shook 1,000,000 square miles of the earth’s -surface must have been of almost inconceivable energy. If -directed entirely to the upheaval of a land region no larger -than England, those forces would have sufficed to have -destroyed utterly every city, town, and village within such a -region; if directed entirely to the upheaval of an oceanic -region, they would have been capable of raising a wave which -would have been felt on every shore-line of the whole earth. -Divided even between the ocean on the one side and a land -region larger than Russia in Europe on the other, those -Vulcanian forces shook the whole of the land region, and sent -athwart the largest of our earth’s oceans a wave which ran -in upon shores 10,000 miles from the centre of disturbance -with a crest thirty feet high. Forces such as these may fairly -be regarded as cosmical; they show unmistakably that the -earth has by no means settled down into that condition of -repose in which some geologists still believe. We may ask -with the late Sir Charles Lyell whether, after contemplating -the tremendous energy thus displayed by the earth, any -geologist will continue to assert that the changes of relative -level of land and sea, so common in former ages of the world, -have now ceased? and agree with him that if, in the face of -such evidence, a geologist persists in maintaining this -favourite dogma, it would be vain to hope, by accumulating -proofs of similar convulsions during a series of ages, to shake -the tenacity of his conviction—</p> - -<div class="poem-container"> -<div class="poem"><div class="stanza"> -<span class="iq">“Si fractus illabatur orbis,<br /></span> -<span class="i0">Impavidum ferient ruinæ.”<br /></span> -</div></div> -</div> - -<p>But there is one aspect in which such mighty sea-waves -as, in 1868 and again in May, 1876, have swept over the surface -of our terrestrial oceans, remains yet to be considered.</p> - -<p><span class="pagenum"><a id="Page_193">193</a></span> -The oceans and continents of our earth must be clearly -discernible from her nearer neighbours among the planets—from -Venus and Mercury on the inner side of her path -around the sun, and from Mars (though under less favourable -conditions) from the outer side. When we consider, -indeed, that the lands and seas of Mars can be clearly -discerned with telescopic aid from our earth at a distance of -forty millions of miles, we perceive that our earth, seen from -Venus at little more than half this distance, must present -a very interesting appearance. Enlarged, owing to greater -proximity, nearly fourfold, having a diameter nearly twice as -great as that of Mars, so that at the same distance her disc -would seem more than three times as large, more brightly -illuminated by the sun in the proportion of about five to two, -she would shine with a lustre exceeding that of Mars, when in -full brightness in the midnight sky, about thirty times; and all -her features would of course be seen with correspondingly -increased distinctness. Moreover, the oceans of our earth -are so much larger in relative extent than those of Mars, -covering nearly three-fourths instead of barely one-half of the -surface of the world they belong to, that they would appeal -as far more marked and characteristic features than the seas -and lakes of Mars. When the Pacific Ocean, indeed, occupies -centrally the disc of the earth which at the moment is -turned towards any planet, nearly the whole of that disc -must appear to be covered by the ocean. Under such -circumstances the passage of a wide-spreading series of waves -over the Pacific, at the rate of about 500 miles an hour, is a -phenomenon which could scarcely fail to be discernible from -Venus or Mercury, if either planet chanced to be favourably -placed for the observation of the earth—always supposing -there were observers in Mercury or Venus, and that these -observers were provided with powerful telescopes.</p> - -<p>It must be remembered that the waves which spread -over the Pacific on August 13–14, 1868, and again on May -9–10, 1876, were not only of enormous range in length -(measured along crest or trough), but also of enormous<span class="pagenum"><a id="Page_194">194</a></span> -breadth (measured from crest to crest, or from trough to -trough). Were it otherwise, indeed, the progress of a wave -forty or fifty feet high (at starting, and thirty-five feet high -after travelling 6000 miles), at the rate of 500 miles per -hour, must have proved destructive to ships in the open -ocean as well as along the shore-line. Suppose, for instance, -the breadth of the wave from crest to crest one mile, then, in -passing under a ship at the rate of 500 miles per hour, the -wave would raise the ship from trough to crest—that is, -through a height of forty feet—in one-thousandth part of an -hour (for the distance from trough to crest is but half the -breadth of the wave), or in less than four seconds, lowering it -again in the same short interval of time, lifting and lowering it -at the same rate several successive times. The velocity with -which the ship would travel upwards and downwards would -be greatest when she was midway in her ascent and descent, -and would then be equal to about the velocity with which a -body strikes the ground after falling from a height of four -yards. It is hardly necessary to say that small vessels subjected -to such tossing as this would inevitably be swamped. -On even the largest ships the effect of such motion would be -most unpleasantly obvious. Now, as a matter of fact, the -passage of the great sea-wave in 1868 was not noticed at all -on board ships in open sea. Even within sight of the shore -of Peru, where the oscillation of the sea was most marked, -the motion was such that its effects were referred to the -shore. We are told that observers on the deck of a United -States’ war steamer distinctly saw the “peaks of the mountains -in the chain of the Cordilleras wave to and fro like reeds in -a storm;” the fact really being that the deck on which they -stood was swayed to and fro. This, too, was in a part of -the sea where the great wave had not attained its open sea -form, but was a rolling wave, because of the shallowness of -the water. In the open sea, we read that the passage of the -great sea-wave was no more noticed than is the passage of -the tidal-wave itself. “Among the hundreds of ships which -were sailing upon the Pacific when its length and breadth<span class="pagenum"><a id="Page_195">195</a></span> -were traversed by the great sea-wave, there was not one in -which any unusual motion was perceived.” The inference -is clear, that the slope of the advancing and following faces -of the great wave was very much less than in the case above -imagined; in other words, that the breadth of the wave -greatly exceeded one mile—amounting, in fact, to many -miles.</p> - -<p>Where the interval between the passage of successive -wave-crests was noted, we can tell the actual breadth of the -wave. Thus, at the Samoan Isles, in 1868, the crests succeeded -each other at intervals of sixteen minutes, corresponding -to eight minutes between crest and trough. But we have -seen, that if the waves were one mile in breadth, the corresponding -interval would be only four seconds, or only one -120th part of eight minutes: it follows, then, that the breadth -of the great wave, where it reached the Samoan Isles in -1868, was about 120 miles.</p> - -<p>Now a wave extending right athwart the Pacific Ocean, -and having a cross breadth of more than 120 miles, would -be discernible as a marked feature of the disc of our earth, -seen under the conditions described above, either from Mercury -or Venus. It is true that the slope of the wave’s -advancing and following surfaces would be but slight, yet -the difference of the illumination under the sun’s rays would -be recognizable. Then, also, it is to be remembered that -there was not merely a single wave, but a succession of many -waves. These travelled also with enormous velocity; and -though at the distance of even the nearest planet, the apparent -motion of the great wave, swift though it was in reality, -would be so far reduced that it would have to be estimated -rather than actually seen, yet there would be no difficulty in -thus perceiving it with the mind’s eye. The rate of motion -indeed would almost be exactly the same as that of the -equatorial part of the surface of Mars, in consequence of the -planet’s rotation; and this (as is well known to telescopists), -though not discernible directly, produces, even in a few -minutes, changes which a good eye can clearly recognize.<span class="pagenum"><a id="Page_196">196</a></span> -We can scarcely doubt then that if our earth were so situated -at any time when one of the great waves generated by Peruvian -earthquakes in traversing the Pacific, that the hemisphere -containing this ocean were turned fully illuminated -towards Venus (favourably placed for observing her), the -disturbance of the Pacific could be observed and measured -by telescopists on that planet.</p> - -<p>Unfortunately there is little chance that terrestrial observers -will ever be able to watch the progress of great waves -athwart the oceans of Mars, and still less that any disturbance -of the frame of Venus should become discernible to us -by its effects. We can scarce even be assured that there -are lands and seas on Venus, so far as direct observation is -concerned, so unfavourably is she always placed for observation; -and though we see Mars under much more favourable -conditions, his seas are too small and would seem to -be too shallow (compared with our own) for great waves to -traverse them such as could be discerned from the earth.</p> - -<p>Yet it is well to remember the possibility that changes -may at times take place in the nearer planets—the terrestrial -planets, as they are commonly called, Mars, Venus, -and Mercury—such as telescopic observation under favourable -conditions might detect. Telescopists have, indeed, -described apparent changes, lasting only for a short time, in -the appearance of one of these planets, Mars, which may -fairly be attributed to disturbances affecting its surface in no -greater degree than the great Peruvian earthquakes have -affected for a time the surface of our earth. For instance, -the American astronomer Mitchel says that on the night of -July 12, 1845, bright polar snows of Mars exhibited an -appearance never noticed at any preceding or succeeding -observation. In the very centre of the white surface appeared -a dark spot, which retained its position during several hours: -on the following evening not a trace of the spot could be -seen. Again the same observer says that on the evening of -August 30, 1845, he observed for the first time a small -bright spot, nearly or quite round, projecting out of the<span class="pagenum"><a id="Page_197">197</a></span> -lower side of the polar spot. “In the early part of the -evening,” he says, “the small bright spot seemed to be partly -buried in the large one. After the lapse of an hour or more -my attention was again directed to the planet, when I was -astonished to find a manifest change in the position of the -small bright spot. It had apparently separated from the -large spot, and the edges alone of the two were now in contact, -whereas when first seen they overlapped by an amount -quite equal to one-third of the diameter of the small one. -This, however, was merely an optical phenomenon, for on -the next evening the spots went through the same apparent -changes as the planet went through the corresponding part -of its rotation. But it showed the spots to be real ice -masses. The strange part of the story is that in the course -of a few days the smaller spot, which must have been a mass -of snow and ice as large as Novaia Zemlia, gradually disappeared. -Probably some great shock had separated an -enormous field of ice from the polar snows, and it had -eventually been broken up and its fragments carried away -from the Arctic regions by currents in the Martian oceans. It -appears to me that the study of our own earth, and of the -changes and occasional convulsions which affect its surface, -gives to the observation of such phenomena as I have just -described a new interest. Or rather, perhaps, it is not too -much to say that the telescopic observations of the planets -derive their only real interest from such considerations.</p> - -<p>I may note in conclusion, that while on the one hand -we cannot doubt that the earth is slowly parting with its -internal heat, and thus losing century by century a portion -of its Vulcanian energy, such phenomena as the Peruvian -earthquakes show that the loss of energy is taking place so -slowly that the diminution during many ages is almost imperceptible. -As I have elsewhere remarked, “When we see -that while mountain ranges were being upheaved or valleys -depressed to their present position, race after race and type -after type lived out on the earth the long lives which belong -to races and to types, we recognize the great work which the<span class="pagenum"><a id="Page_198">198</a></span> -earth’s subterranean forces are still engaged upon. Even -now continents are being slowly depressed or upheaved, -even now mountain ranges are being raised to a different -level, table-lands are being formed, great valleys are being -gradually scooped out; old shore-lines shift their place, old -soundings vary; the sea advances in one place and retires -in another; on every side nature’s plastic hand is still at -work, modelling and remodelling the earth, and making it -constantly a fit abode for those who dwell upon it.”</p> - -<hr /> - -<p><span class="pagenum"><a id="Page_199">199</a></span></p> - -<div class="chapter"> -<h2><a id="STRANGE_SEA_CREATURES"></a><i>STRANGE SEA CREATURES.</i></h2> -</div> - -<blockquote> - -<p>“We ought to make up our minds to dismiss as idle prejudices, or, -at least, suspend as premature, any preconceived notion of what <em>might</em>, -or what <em>ought to</em>, <em>be</em> the order of nature, and content ourselves with -observing, as a plain matter of fact, what <em>is</em>.”—Sir <span class="smcap">J. Herschel</span>, -“Prelim. Disc.” page 79.</p></blockquote> - -<p class="p2 in0">The fancies of men have peopled three of the four so-called -elements, earth, air, water, and fire, with strange forms of -life, and have even found in the salamander an inhabitant -for the fourth. On land the centaur and the unicorn, in the -air the dragon and the roc, in the water tritons and mermaids, -may be named as instances among many of the -fabulous creatures which have been not only imagined but -believed in by men of old times. Although it may be -doubted whether men have ever invented any absolutely -imaginary forms of life, yet the possibility of combining -known forms into imaginary, and even impossible, forms, -must be admitted as an important element in any inquiry -into the origin of ideas respecting such creatures as I have -named. One need only look through an illuminated manuscript -of the Middle Ages to recognize the readiness with -which imaginary creatures can be formed by combining, or -by exaggerating, the characteristics of known animals. -Probably the combined knowledge and genius of all the -greatest zoologists of our time would not suffice for the -invention of an entirely new form of animal which yet should -be zoologically possible; but to combine the qualities of -several existent animals in a single one, or to conceive an<span class="pagenum"><a id="Page_200">200</a></span> -animal with some peculiarity abnormally developed, is within -the capacity of persons very little acquainted with zoology, -nay, is perhaps far easier to such persons than it would be -to an Owen, a Huxley, or a Darwin. In nearly every case, -however, the purely imaginary being is to be recognized by -the utter impossibility of its actual existence. If it be a -winged man, arms and wings are both provided, but the -pectoral muscles are left unchanged. A winged horse, in -like manner, is provided with wings, without any means of -working them. A centaur, as in the noble sculptures of -Phidias, has the upper part of the trunk of a man superadded, -not to the hind quarters of a horse or other quadruped, but -to the entire trunk of such an animal, so that the abdomen -of the human figure lies <em>between</em> the upper half of the human -trunk and the corresponding part of the horse’s trunk, an -arrangement anatomically preposterous. Without saying -that every fabulous animal which was anatomically and -zoologically possible, had a real antitype, exaggerated though -the fabulous form may have been, we must yet admit that -errors so gross marked the conception of all the really -imaginary animals of antiquity, that any fabulous animal -found to accord fairly well with zoological possibilities may -be regarded, with extreme probability, as simply the exaggerated -presentation of some really existent animal. The -inventors of centaurs, winged and man-faced bulls, many-headed -dogs, harpies, and so forth, were utterly unable to -invent a possible new animal, save by the merest chance, -the probability of which was so small that it may fairly be -disregarded.</p> - -<p>This view of the so-called fabulous animals of antiquity -has been confirmed by the results of modern zoological -research. The merman, zoologically possible (not in all -details, of course, but generally), has found its antitype in -the dugong and the manatee; the roc in the condor, or -perhaps in those extinct species whose bones attest their -monstrous proportions; the unicorn in the rhinoceros; even -the dragon in the pterodactyl of the green-sand; while the<span class="pagenum"><a id="Page_201">201</a></span> -centaur, the minotaur, the winged horse, and so forth, have -become recognized as purely imaginary creatures, which had -their origin simply in the fanciful combination of known -forms, no existent creatures having even suggested these -monstrosities.</p> - -<p>It is not to be wondered at that the sea should have -been more prolific in monstrosities and in forms whose real -nature has been misunderstood. Land animals cannot long -escape close observation. Even the most powerful and -ferocious beasts must succumb in the long run to man, and -in former ages, when the struggle was still undecided between -some race of animals and savage man, individual -specimens of the race must often have been killed, and the -true appearance of the animal determined. Powerful winged -animals might for a longer time remain comparatively -mysterious creatures even to those whom they attacked, or -whose flocks they ravaged. A mighty bird, or a pterodactylian -creature (a late survivor of a race then fast dying -out), might swoop down on his prey and disappear with it -too swiftly to be made the subject of close scrutiny, still less -of exact scientific observation. Yet the general characteristics -even of such creatures would before long be known. From -time to time the strange winged monster would be seen -hovering over the places where his prey was to be found. -Occasionally it would be possible to pierce one of the race -with an arrow or a javelin; and thus, even in those remote -periods when the savage progenitors of the present races of -man had to carry on a difficult contest with animals now -extinct or greatly reduced in power, it would become possible -to determine accurately the nature of the winged enemy. -But with sea creatures, monstrous, or otherwise, the case -would be very different. To this day we remain ignorant -of much that is hidden beneath the waves of the “hollow-sounding -and mysterious main.” Of far the greater number -of sea creatures, it may truly be said that we never see any -specimens except by accident, and never obtain the body of -any except by very rare accident. Those creatures of the<span class="pagenum"><a id="Page_202">202</a></span> -deep sea which we are best acquainted with, are either those -which are at once very numerous and very useful as food or -in some other way, or else those which are very rapacious -and thus expose themselves, by their attacks on men, to -counter-attack and capture or destruction. In remote times, -when men were less able to traverse the wide seas, when, -on the one hand, attacks from great sea creatures were more -apt to be successful, while, on the other, counter-attack was -much more dangerous, still less would be known about the -monsters of the deep. Seen only for a few moments as he -seized his prey, and then sinking back into the depths, a -sea monster would probably remain a mystery even to those -who had witnessed his attack, while their imperfect account -of what they had seen would be modified at each repetition -of the story, until there would remain little by which the -creature could be identified, even if at some subsequent -period its true nature were recognized. We can readily -understand, then, that among the fabulous creatures of -antiquity, even of those which represented actually existent -races incorrectly described, the most remarkable, and those -zoologically the least intelligible, would be the monsters of -the deep sea. We can also understand that even the -accounts which originally corresponded best with the truth -would have undergone modifications much more noteworthy -than those affecting descriptions of land animals or winged -creatures—simply because there would be small chance of -any errors thus introduced being corrected by the study of -freshly discovered specimens.</p> - -<p>We may, perhaps, explain in this way the strange account -given by Berosus of the creature which came up from the -Red Sea, having the body of a fish but the front and head of -a man. We may well believe that this animal was no other -than a dugong, or halicore (a word signifying sea-maiden), -a creature inhabiting the Indian Ocean to this day, and which -might readily find its way into the Red Sea. But the account -of the creature has been strangely altered from the original -narrative, if at least the original narrative was correct. For,<span class="pagenum"><a id="Page_203">203</a></span> -according to Berosus, the animal had two human feet which -projected from each side of the tail; and, still stranger, it -had a human voice and human language. “This strange -monster sojourned among the rude people during the day, -taking no food, but retiring to the sea again at night, and -continued for some time teaching them the arts of civilized -life.” A picture of this stranger is said to have been preserved -at Babylon for many centuries. With a probable -substratum of truth, the story in its latest form is as fabulous -as Autolycus’s “ballad of a fish that appeared upon the -coast, on Wednesday the fourscore of April, forty thousand -fathoms above water, and sang a ballad against the hard -hearts of maids.”</p> - -<p>It is singular, by the way, how commonly the power of -speech, or at least of producing sounds resembling speech -or musical notes, was attributed to the creature which -imagination converted into a man-fish or woman-fish. -Dugongs and manatees make a kind of lowing noise, which -could scarcely be mistaken under ordinary conditions for the -sound of the human voice. Yet, not only is this peculiarity -ascribed to the mermaid and siren (the merman and triton -having even the supposed power of blowing on conch-shells), -but in more recent accounts of encounters with creatures -presumably of the seal tribe and allied races, the same -feature is to be noticed. The following account, quoted by -Mr. Gosse from a narrative by Captain Weddell, the well-known -geographer, is interesting for this reason amongst -others. It also illustrates well the mixture of erroneous details -(the offspring, doubtless, of an excited imagination) with the -correct description of a sea creature actually seen:—“A -boat’s crew were employed on Hall’s Island, when one of -the crew, left to take care of some produce, saw an animal -whose voice was musical. The sailor had lain down, and at -ten o’clock he heard a noise resembling human cries, and as -daylight in these latitudes never disappears at this season” -(the Antarctic summer), “he rose and looked around, but, -on seeing no person, returned to bed. Presently he heard<span class="pagenum"><a id="Page_204">204</a></span> -the noise again; he rose a second time, but still saw nothing. -Conceiving, however, the possibility of a boat being upset, -and that some of the crew might be clinging to detached -rocks, he walked along the beach a few steps and heard the -noise more distinctly but in a musical strain. Upon searching -around, he saw an object lying on a rock a dozen yards -from the shore, at which he was somewhat frightened. The -face and shoulders appeared of human form and of a reddish -colour; over the shoulders hung long green hair; the tail -resembled that of the seal, but the extremities of the arms -he could not see distinctly. The creature continued to -make a musical noise while he gazed about two minutes, and -on perceiving him it disappeared in an instant. Immediately, -when the man saw his officer, he told this wild tale, -and to add weight to his testimony (being a Romanist) he -made a cross on the sand, which he kissed, as making oath -to the truth of his statement. When I saw him he told the -story in so clear and positive a manner, making oath to its -truth, that I concluded he must really have seen the animal -he described, or that it must have been the effects of a disturbed -imagination.”</p> - -<p>In this story all is consistent with the belief that the -sailor saw an animal belonging to the seal family (of a -species unknown to him), except the green hair. But the -hour was not very favourable to the discerning of colour, -though daylight had not quite passed away, and as Gosse -points out, since golden-yellow fur and black fur are found -among Antarctic seals, the colours may be intermingled in -some individuals, producing an olive-green tint, which, by -contrast with the reddish skin, might be mistaken for a full -green. Considering that the man had been roused from -sleep and was somewhat frightened, he would not be likely -to make very exact observations. It will be noticed that it -was only at first that he mistook the sounds made by the -creature for human cries; afterwards he heard only the same -<em>noise</em>, but in a musical strain. Now with regard to the -musical sounds said to have been uttered by this creature,<span class="pagenum"><a id="Page_205">205</a></span> -and commonly attributed to creatures belonging to families -closely allied to the seals, I do not know that any attempt -has yet been made to show that these families possess the -power of emitting sounds which can properly be described -as musical. It is quite possible that the Romanist sailor’s -ears were not very nice, and that any sound softer than a -bellow seemed musical to him. Still, the idea suggests itself -that possibly seals, like some other animals, possess a note -not commonly used, but only as a signal to their mates, and -never uttered when men or other animals are known to be -near. It appears to me that this is rendered probable by -the circumstance that seals are fond of music. Darwin -refers to this in his treatise on Sexual Selection (published -with his “Descent of Man”), and quotes a statement to the -effect that the fondness of seals for music “was well known -to the ancients, and is often taken advantage of by hunters -to the present day.” The significance of this will be understood -from Darwin’s remark immediately following, that -“with all these animals, the males of which during the season -of courtship incessantly produce musical notes or mere -rhythmical sounds, we must believe that the females are -able to appreciate them.”</p> - -<p>The remark about the creature’s arms seems strongly to -favour the belief that the sailor intended his narrative to be -strictly truthful. Had he wished to excite the interest of his -comrades by a marvellous story, he certainly would have -described the creature as having well-developed human -hands.</p> - -<p>Less trustworthy by far seem some of the stories which -have been told of animals resembling the mermaid of antiquity. -It must always be remembered, however, that in all -probability we know very few among the species of seals and -allied races, and that some of these species may present, in -certain respects and perhaps at a certain age, much closer -resemblance to the human form than the sea-lion, seal, -manatee, or dugong.</p> - -<p>We cannot, for instance, attach much weight to the following<span class="pagenum"><a id="Page_206">206</a></span> -story related by Hudson, the famous navigator:—“One -of our company, looking overboard, saw a mermaid -and calling up some of the company to see her, one more -came up, and by that time she was come close to the ship’s -side, looking earnestly on the men. A little after a sea -came and overturned her. From the navel upward her back -and breasts were like a woman’s, as they say that saw her; -her body as big as one of us; her skin very white; and long -hair hanging down behind, of colour black. In her going -down they saw her tail, which was like the tail of a porpoise -and speckled like a mackerel.” If Hudson himself had seen -and thus described the creature it would have been possible -to regard the story with some degree of credence; but his -account of what Thomas Hilles and Robert Rayner, men -about whose character for veracity we know nothing, <em>said</em> -they saw, is of little weight. The skin very white, and long -hair hanging down behind, are especially suspicious features -of the narrative; and were probably introduced to dispose -of the idea, which others of the crew may have advanced, -that the creature was only some kind of seal after all. The -female seal (<i>Phoca Greenlandica</i> is the pretty name of the -animal) is not, however, like the male, tawny grey, but -dusky white, or yellowish straw-colour, with a tawny tint on -the back. The young alone could be called “very white.” -They are so white in fact as scarcely to be distinguishable -when lying on ice and snow, a circumstance which, as -Darwin considers, serves as a protection for these little -fellows.</p> - -<p>The following story, quoted by Gosse from Dr. Robert -Hamilton’s able “History of the Whales and Seals,” compares -favourably in some respects with the last narrative:—“It -was reported that a fishing-boat off the island of Yell, one of -the Shetland group, had captured a mermaid by its getting -entangled in the lines! The statement is, that the animal -is about three feet long, the upper part of the body resembling -the human, with protuberant mammæ like a woman; -the face, the forehead, and neck, were short, and resembling<span class="pagenum"><a id="Page_207">207</a></span> -those of a monkey; the arms, which were small, were kept -folded across the breast; the fingers were distinct, not -webbed; a few stiff long bristles were on the top of the head, -extending down to the shoulders, and these it could erect -and depress at pleasure, something like a crest. The inferior -part of the body was like a fish. The skin was smooth and -of a grey colour. It offered no resistance, nor attempted to -bite, but uttered a low, plaintive sound. The crew, six in -number, took it within their boat; but superstition getting -the better of curiosity, they carefully disentangled it from the -lines and a hook which had accidentally fastened in the -body, and returned it to its native element. It instantly -dived, descending in a perpendicular direction.” “They -had the animal for three hours within the boat; the body -was without scales or hair; of a silvery grey colour above, -and white below, like the human skin; no gills were observed, -nor fins on the back or belly. The tail was like -that of the dog-fish; the mammæ were about as large as those -of a woman; the mouth and lips were very distinct, and -resembled the human.”</p> - -<p>This account, if accepted in all its details, would certainly -indicate that an animal of some species before unknown had -been captured. But it is doubtful how much reliance can -be placed on the description of the animal. Mr. Gosse, -commenting upon the case, says that the fishermen cannot -have been affected by fear in such sort that their imagination -exaggerated the resemblance of the creature to the -human form. “For the mermaid,” he says, “is not an -object of terror to the fishermen; it is rather a welcome -guest, and danger is to be apprehended only from its experiencing -bad treatment.” But then this creature had not -been treated as a specially welcome guest. The crew had captured -it; and probably not without some degree of violence; -for though it offered no resistance it uttered a plaintive cry. -And that hook which “had accidentally fastened in the -body” has a very suspicious look. If the animal could have -given its own account of the capture, probably the hook<span class="pagenum"><a id="Page_208">208</a></span> -would not have been found to have fastened in the body -altogether by accident. Be this as it may, the fishermen -were so far frightened that superstition got the better of -curiosity; so that, as they were evidently very foolish fellows, -their evidence is scarcely worth much. There are, however, -only two points in their narrative which do not seem easily -reconciled with the belief that they had captured a rather -young female of a species closely allied to the common seal—the -distinct unwebbed fingers and the small arms folded -across the breast. Other points in their description suggest -marked differences in degree from the usual characteristics -of the female seal; but these two alone seem to differ absolutely -in kind. Considering all the circumstances of the -narrative, we may perhaps agree with Mr. Gosse to this -extent, that, combined with other statements, the story induces -a strong suspicion that the northern seas may hold -forms of life as yet uncatalogued by science.</p> - -<p>The stories which have been related about monstrous -cuttle-fish have only been fabulous in regard to the dimensions -which they have attributed to these creatures. Even -in this respect it has been shown, quite recently, that some -of the accounts formerly regarded as fabulous fell even short -of the truth. Pliny relates, for instance, that the body of a -monstrous cuttle-fish, of a kind known on the Spanish coast, -weighed, when captured, 700 lbs., the head the same, the -arms being 30 feet in length. The entire weight would probably -have amounted to about 2000 lbs. But we shall presently -see that this weight has been largely exceeded by -modern specimens. It was, however, in the Middle Ages -that the really fabulous cuttle-fish flourished—the gigantic -kraken, “liker an island than an animal,” according to credulous -Bishop Pontoppidan, and able to destroy in its -mighty arms the largest galleons and war ships of the fourteenth -and fifteenth centuries.</p> - -<p>It is natural that animals really monstrous should be -magnified by the fears of those who have seen or encountered -them, and still further magnified afterwards by tradition.<span class="pagenum"><a id="Page_209">209</a></span> -Some specimens of cuttle-fish which have been -captured wholly, or in part, indicate that this creature sometimes -attains such dimensions that but little magnifying -would be needed to suggest even the tremendous proportions -of the fabulous kraken. In 1861, the French war-steamer -<i>Alecton</i> encountered a monstrous cuttle, on the -surface of the sea, about 120 miles north-east of Teneriffe. -The crew succeeded in slipping a noose round the body, but -unfortunately the rope slipped, and, being arrested by the -tail fin, pulled off the tail. This was hauled on board, and -found to weigh over 40 lbs. From a drawing of the animal, -the total length without the arms was estimated at 50 feet, -and the weight at 4000 lbs., nearly twice the weight of -Pliny’s monstrous cuttle-fish, long regarded as fabulous. In -one respect this creature seems to have been imperfect, the -two long arms usually possessed by cuttle-fish of the kind -being wanting. Probably it had lost these long tentacles in -a recent encounter with some sea enemy, perhaps one of its -own species. Quite possibly it may have been such recent -mutilation which exposed this cuttle-fish to successful -attack by the crew of the <i>Alecton</i>.</p> - -<p>A cuttle-fish of about the same dimensions was encountered -by two fishermen in 1873, in Conception Bay, -Newfoundland. When they attacked it, the creature threw -its long arms across the boat, but the fishermen with an axe -cut off these tentacles, on which the cephalopod withdrew in -some haste. One of the arms was preserved, after it had -lost about 6 feet of its length. Even thus reduced it -measured 19 feet; and as the fishermen estimate that the arm -was struck off about 10 feet from the body, it follows that the -entire length of the limb must have been about 35 feet. -They estimated the body at 60 feet in length and 5 feet in -diameter—a monstrous creature! It was fortunate for these -fishermen that they had an axe handy for its obtrusive tentacles, -as with so great a mass and the great propulsive -power possessed by all cephalopods, it might readily have -upset their small boat. Once in the water, they would have<span class="pagenum"><a id="Page_210">210</a></span> -been at the creature’s mercy—a quality which, by all accounts, -the cuttle-fish does not possess to any remarkable -extent.</p> - -<p>Turn we, however, from the half fabulous woman-fish, -and the exaggeratedly monstrous cuttle-fish, to the famous -sea-serpent, held by many to be the most utterly fabulous of -all fabled creatures, while a few, including some naturalists -of distinction, stoutly maintain that the creature has a real -existence, though whether it be rightly called a sea-serpent -or not is a point about which even believers are extremely -doubtful.</p> - -<p>It may be well, in the first place, to remark that in -weighing the evidence for and against the existence of this -creature, and bearing on the question of its nature (if its -existence be admitted), we ought not to be influenced by -the manifest falsity of a number of stories relating to supposed -encounters with this animal. It is probable that, but -for these absurd stories, the well-authenticated narratives -relating to the creature, whatever it may be, which has been -called the sea-serpent, would have received much more -attention than has heretofore been given to them. It is also -possible that some narratives would have been published -which have been kept back from the fear lest a truthful -(though possibly mistaken) account should be classed with -the undoubted untruths which have been told respecting the -great sea-serpent. It cannot be denied that in the main the -inventions and hoaxes about the sea-serpent have come -chiefly from American sources. It is unfortunately supposed -by too many of the less cultured sons of America that (to use -Mr. Gosse’s expression) “there is somewhat of wit in gross -exaggerations or hoaxing inventions.” Of course an -American gentleman—using the word “in that sense in which -every man may be a gentleman,” as Twemlow hath it—would -as soon think of uttering a base coin as a deliberate untruth -or foolish hoax. But it is thought clever, by not a few in -America who know no better, to take any one in by an -invention. Some, perhaps but a small number, of the newspapers<span class="pagenum"><a id="Page_211">211</a></span> -set a specially bad example in this respect, giving -room in their columns for pretended discoveries in various -departments of science, elaborate accounts of newly discovered -animals, living or extinct, and other untruths which -would be regarded as very disgraceful indeed by English -editors. Such was the famous “lunar hoax,” published in -the New York <cite>Sun</cite> some forty years ago; such the narrative, -in 1873, of a monstrous fissure which had been discerned in -the body of the moon, and threatened to increase until the -moon should be cloven into two unequal parts; such the -fables which have from time to time appeared respecting -the sea-serpent. But it would be as unreasonable to reject, -because of these last-named fables, the narratives which have -been related by quiet, truth-loving folk, and have borne close -and careful scrutiny, as it would be to reject the evidence -given by the spectroscope respecting the existence of iron -and other metals in the sun because an absurd story had -told how creatures in the moon had been observed to make -use of metal utensils or to adorn the roofs of their temples -with metallic imitations of wreathed flames.</p> - -<p>The oldest accounts on record of the appearance of a -great sea creature resembling a serpent are those quoted by -Bishop Pontoppidan, in his description of the natural history -of his native country, Norway. Amongst these was one confirmed -by oath taken before a magistrate by two of the crew -of a ship commanded by Captain de Ferry, of the Norwegian -navy. The captain and eight men saw the animal, near -Molde, in August, 1747. They described it as of the general -form of a serpent, stretched on the surface in receding coils -(meaning, probably, the shape assumed by the neck of a -swan when the head is drawn back). The head, which resembled -that of a horse, was raised two feet above the -water.</p> - -<p>In August, 1817, a large marine animal, supposed to be -a serpent, was seen near Cape Ann, Massachusetts. Eleven -witnesses of good reputation gave evidence on oath before -magistrates. One of these magistrates had himself seen the<span class="pagenum"><a id="Page_212">212</a></span> -creature, and corroborated the most important points of the -evidence given by the eleven witnesses. The creature had -the appearance of a serpent, dark brown in colour (some -said mottled), with white under the head and neck. Its -length was estimated at from 50 to 100 feet. The head was -in shape like a serpent’s, but as large as a horse’s. No mane -was noticed. Five of the witnesses deposed to protuberances -on the back; four said the back was straight; the -other two gave no opinion on this point. The magistrate -who had seen the animal considered the appearance of protuberances -was due to the bendings of the body while in -rapid motion.</p> - -<p>In 1848, when the captain of the British frigate <i>Dædalus</i> -had published an account of a similar animal seen by him -and several of his officers and crew, the Hon. Colonel T. H. -Perkins, of Boston, who had seen the animal on the occasion -just mentioned in 1817, gave an account (copied from a -letter written in 1820) of what he had witnessed. It is -needless to quote those points which correspond with what -has been already stated. Colonel Perkins noticed “an -appearance in the front of the head like a single horn, about -nine inches to a foot in length, shaped like a marlinspike, -which will presently be explained. I left the place,” he -proceeds, “fully satisfied that the reports in circulation, -though differing in details, were essentially correct.” He -relates how a person named Mansfield, “one of the most -respectable inhabitants of the town, who had been such an -unbeliever in the existence of this monster that he had not -given himself the trouble to go from his house to the harbour -when the report was first made,” saw the animal from a bank -overlooking the harbour. Mr. Mansfield and his wife agreed -in estimating the creature’s length at 100 feet. Several -crews of coasting vessels saw the animal, <em>in some instances -within a few yards</em>. “Captain Tappan,” proceeds Colonel -Perkins, “a person well known to me, saw him with his head -above water two or three feet, at times moving with great -rapidity, at others slowly. He also saw what explained the<span class="pagenum"><a id="Page_213">213</a></span> -appearance which I have described of a horn on the front of -the head. This was doubtless what was observed by Captain -Tappan to be the tongue, thrown in an upright position -from the mouth, and having the appearance which I have -given to it. One of the revenue cutters, whilst in the -neighbourhood of Cape Ann, had an excellent view of him -at a few yards’ distance; he moved slowly, and upon the -appearance of the vessel sank and was seen no more.”</p> - -<p>Fifteen years later, in May 1833, five British officers—Captain -Sullivan, Lieutenants Maclachlan and Malcolm of -the Rifle Brigade, Lieutenant Lyster of the Artillery, and -Mr. Snee of the Ordnance—when cruising in a small yacht -off Margaret’s Bay, not far from Halifax, “saw the head and -neck of some denizen of the deep, precisely like those of a -common snake, in the act of swimming, the head so elevated -and thrown forward by the curve of the neck as to enable us -to see the water under and beyond it.” They judged its -length to exceed 80 feet. “There could be no mistake nor -delusion, and we were all perfectly satisfied that we had -been favoured with a view of the ‘true and veritable sea-serpent,’ -which had been generally considered to have -existed only in the brain of some Yankee skipper, and -treated as a tale not entitled to belief.” Dowling, a man-of-war’s -man they had along with them, made the following -unscientific but noteworthy comment: “Well, I’ve sailed in -all parts of the world, and have seen rum sights too in my -time, but this is the queerest thing I ever see.” “And -surely,” adds Captain Sullivan, “Jack Dowling was right.” -The description of the animal agrees in all essential respects -with previous accounts, but the head was estimated at about -six feet in length—considerably larger, therefore, than a -horse’s head.</p> - -<p>But unquestionably the account of the sea-serpent which -has commanded most attention was that given by the captain, -officers, and crew of the British frigate <i>Dædalus</i>, Captain -M’Quhæ, in 1848. The <cite>Times</cite> published on October 9, -1848, a paragraph stating that the sea-serpent had been seen<span class="pagenum"><a id="Page_214">214</a></span> -by the captain and most of the officers and crew of this ship, -on her passage home from the East Indies. The Admiralty -inquired at once into the truth of the statement, and the -following is abridged from Captain M’Quhæ’s official reply, -addressed to Admiral Sir W. H. Gage.</p> - -<p>“Sir,—In reply to your letter, requiring information as to -the truth of a statement published in the <cite>Times</cite> newspaper, -of a sea-serpent of extraordinary dimensions having been -seen from the <i>Dædalus</i>, I have the honour to inform you -that at 5 p.m., August 6 last, in latitude 24° 44´ S., longitude -9° 22´ E., the weather dark and cloudy, wind fresh from -N.W., with long ocean swell from S.W., the ship on the -port tack, heading N.E. by N., Mr. Sartoris, midshipman, -reported to Lieutenant E. Drummond (with whom, and Mr. -W. Barrett, the master, I was walking the quarter-deck) -something very unusual rapidly approaching the ship from -before the beam. The object was seen to be an enormous -serpent, with head and shoulders kept about four feet -constantly above the surface of the sea, as nearly as we -could judge; at least 60 feet of the animal was on the -surface, no part of which length was used, so far as we -could see, in propelling the animal either by vertical or -horizontal undulation. It passed quietly, <em>but so closely -under our lee quarter that, had it been a man of my acquaintance, -I should easily have recognized his features with -the naked eye</em>. It did not, while visible, deviate from its -course to the S.W., which it held on at the pace of from 12 -to 15 miles per hour, as if on some determined purpose. -The diameter of the serpent was from 15 to 16 inches -behind the head, which was, without any doubt, that of a -snake. Its colour was a dark brown, with yellowish white -about the throat. It did not once, while within the range -of view from our glasses, sink below the surface. It had no -fins, but something like the mane of a horse, or rather a -bunch of sea-weed, washed about its back. It was seen by -the quarter-master, the boatswain’s mate, and the man at -the wheel, in addition to myself and the officers above-<span class="pagenum"><a id="Page_215">215</a></span>mentioned. -I am having a drawing of the serpent made -from a sketch taken immediately after it was seen, which I -hope to have ready for my Lords Commissioners of the -Admiralty by to-morrow’s post.—Peter M’Quhæ, Captain.”</p> - -<p>The drawing here mentioned was published in the <cite>Illustrated -London News</cite> for October 28, 1848, being there -described as made “under the supervision of Captain -M’Quhæ, and his approval of the authenticity of the details -as to position and form.”</p> - -<p>The correspondence and controversy elicited by the -statement of Captain M’Quhæ were exceedingly interesting. -It is noteworthy, at the outset, that few, perhaps none, who -had read the original statement, suggested the idea of illusion, -while it need hardly perhaps be said that no one -expressed the slightest doubt as to the <i xml:lang="la" lang="la">bona fides</i> of Captain -M’Quhæ and his fellow-witnesses. These points deserve -attention, because, in recent times, the subject of the sea-serpent -has been frequently mentioned in public journals -and elsewhere as though no accounts of the creature had -ever been given which had been entitled to credence. I -proceed to summarise the correspondence which followed -M’Quhæ’s announcement. The full particulars will be -found in Mr. Gosse’s interesting work, the “Romance of -Natural History,” where, however, as it seems to me, the -full force of the evidence is a little weakened, for all save -naturalists, by the introduction of particulars not bearing -directly on the questions at issue.</p> - -<p>Among the earliest communications was one from Mr. J. -D. M. Stirling, a gentleman who, during a long residence in -Norway, had heard repeated accounts of the sea-serpent in -Norwegian seas, and had himself seen a fish or reptile at a -distance of a quarter of a mile, which, examined through -a telescope, corresponded in appearance with the sea-serpent -as usually described. This communication was chiefly interesting, -however, as advancing the theory that the supposed -sea-serpent is not a serpent at all, but a long-necked plesiosaurian. -This idea had been advanced earlier, but without<span class="pagenum"><a id="Page_216">216</a></span> -his knowledge, by Mr. E. Newman, the editor of the -<cite>Zoologist</cite>. Let us briefly inquire into the circumstances -which suggest the belief.</p> - -<p>If we consider the usual account of the sea-serpent, we -find one constant feature, which seems entirely inconsistent -with the belief that the creature can be a serpent. The -animal has always shown a large portion of its length, from -20 to 60 feet, above the surface of the water, and without any -evident signs of undulation, either vertically or horizontally. -Now, apart from all zoological evidence, our knowledge of -physical laws will not permit us to believe that the portion -thus visible above the surface was propelled by the undulations -of a portion concealed below the surface, unless this -latter portion largely exceeded the former in bulk. A true -fish does not swim for any length of time with any but a very -small portion of its body above water; probably large eels -never show even a head or fin above water for more than a -few seconds when not at rest. Cetaceans, owing to the -layers of blubber which float them up, remain often for a -long time with a portion of their bulk out of the water, and -the larger sort often swim long distances with the head and -fore-part out of water. But, even then, the greater part of -the creature’s bulk is under water, and the driving apparatus, -the anterior fins and the mighty tail, are constantly under -water (when the animal is urging its way horizontally, be it -understood). A sea creature, in fact, whatever its nature, -which keeps any considerable volume of its body out of -water constantly, while travelling a long distance, must of -necessity have a much greater volume all the time under -water, and must have its propelling apparatus under water. -Moreover, if the propulsion is not effected by fins, paddles, -a great flat tail, or these combined, but by the undulations -of the animal’s own body, then the part out of water must of -necessity be affected by these undulations, unless it is very -small in volume and length compared with the part under -water. I assert both these points as matters depending on -physical laws, and without fear that the best-informed<span class="pagenum"><a id="Page_217">217</a></span> -zoologist can adduce any instances to the contrary. It is in -fact physically impossible that such instances should exist.</p> - -<p>It would not be saying too much to assert that if the so-called -sea-serpent were really a serpent, its entire length -must be nearer 1000 than 100 feet. This, of course, is -utterly incredible. We are, therefore, forced to the belief -that the creature is not a serpent. If it were a long-necked -reptile, with a concealed body much bulkier than the neck, -the requirements of floatation would be satisfied; if to that -body there were attached powerful paddles, the requirements -of propulsion would be satisfied. The theory, then, suggested, -first by Mr. Newman, later but independently by Mr. -Stirling, and advocated since by several naturalists of repute, -is simply that the so-called sea-serpent is a modern representative -of the long-necked plesiosaurian reptile to which has -been given the name of the <i>enaliosaurus</i>. Creatures of this -kind prevailed in that era when what is called the lias was -formed, a fossiliferous stratum belonging to the secondary or -mesozoic rocks. They are not found in the later or tertiary -rocks, and thereon an argument might be deduced against -their possible existence in the present, or post-tertiary, -period; but, as will presently be shown, this argument is far -from being conclusive. The enaliosaurian reptiles were -“extraordinary,” says Lyell, “for their number, size, and -structure.” Like the ichthyosauri, or fish-lizards, the enaliosauri -(or serpent-turtles, as they might almost be called) -were carnivorous, their skeletons often enclosing the fossilized -remains of half-digested fishes. They had extremely long -necks, with heads very small compared with the body. They -are supposed to have lived chiefly in narrow seas and -estuaries, and to have breathed air like the modern whales -and other aquatic mammals. Some of them were of formidable -dimensions, though none of the skeletons yet discovered -indicate a length of more than 35 feet. It is not, however, -at all likely that the few skeletons known indicate the full -size attained by these creatures. Probably, indeed, we have -the remains of only a few out of many species, and some<span class="pagenum"><a id="Page_218">218</a></span> -species existing in the mesozoic period may have as largely -exceeded those whose skeletons have been found, as the boa-constrictor -exceeds the common ringed snake. It is also -altogether probable that in the struggle for existence during -which the enaliosaurian reptiles have become <em>almost</em> extinct -(according to the hypothesis we are considering), none but -the largest and strongest had any chance, in which case the -present representatives of the family would largely exceed in -bulk their progenitors of the mesozoic period.</p> - -<p>A writer in the <cite>Times</cite> of November 2, 1848, under the -signature F. G. S., pointed out how many of the external -characters of the creature seen from the <i>Dædalus</i> corresponded -with the belief that it was a long-necked plesiosaurus. -“Geologists,” he said, “are agreed in the inference that the -plesiosauri carried their necks, which must have resembled -the bodies of serpents, above the water, while their propulsion -was effected by large paddles working beneath, the -short but stout tail acting the part of a rudder.... In the -letter and drawing of Captain M’Quhæ ... we have ... -the short head, the serpent-like neck, carried several feet -above the water. Even the bristly mane in certain parts -of the back, so unlike anything found in serpents, has its -analogue in the iguana, to which animal the plesiosaurus -has been compared by some geologists. But I would most -of all insist upon the peculiarity of the animal’s progression, -which could only have been effected with the evenness and -at the rate described by an apparatus of fins or paddles, not -possessed by serpents, but existing in the highest perfection -in the plesiosaurus.”</p> - -<p>At this stage a very eminent naturalist entered the field—Professor -Owen. He dwelt first on a certain characteristic -of Captain M’Quhæ’s letter which no student of science -could fail to notice—the definite statement that the creature -<em>was</em> so and so, where a scientific observer would simply -have said that the creature presented such and such characteristics. -“No sooner was the captain’s attention called to -the object,” says Professor Owen, “than ‘it was discovered<span class="pagenum"><a id="Page_219">219</a></span> -to be an enormous serpent,’” though in reality the true -nature of the creature could not be determined even from -the observations made during the whole time that it remained -visible. Taking, however, “the more certain characters,” -the “head with a convex, moderately capacious cranium, -short, obtuse muzzle, gape not extending further than to beneath -the eye, which (the eye) is rather small, round, filling -closely the palpebral aperture” (that is, the eyelids fit -closely<a id="FNanchor_25" href="#Footnote_25" class="fnanchor">25</a>); “colour and surface as stated; nostrils indicated -in the drawing by a crescentic mark at the end of the nose -or muzzle. All these,” proceeds Owen, “are the characters -of the head of a warm-blooded mammal, none of them those -of a cold-blooded reptile or fish. Body long, dark brown, -not undulating, without dorsal or other apparent fins, ‘but -something like the mane of a horse, or rather a bunch of -sea-weed, washed about its back.’” He infers that the -creature had hair, showing only where longest on the back, -and therefore that the animal was not a mammal of the -whale species but rather a great seal. He then shows that -the sea-elephant, or <i>Phoca proboscidea</i>, which attains the -length of from 20 to 30 feet, was the most probable member -of the seal family to be found about 300 miles from the -western shore of the southern end of Africa, in latitude -24° 44´. Such a creature, accidentally carried from its -natural domain by a floating iceberg, would have (after its -iceberg had melted) to urge its way steadily southwards, as -the supposed sea-serpent was doing; and probably the creature -approached the <i>Dædalus</i> to scan her “capabilities as a -resting-place, as it paddled its long, stiff body past the ship.” -“In so doing it would raise a head of the form and colour -described and delineated by Captain M’Quhæ”—its head -only, be it remarked, corresponding with the captain’s description. -The neck also would be of the right diameter.<span class="pagenum"><a id="Page_220">220</a></span> -The thick neck, passing into an inflexible trunk, the longer -and coarser hair on the upper part of which would give rise -to the idea “explained by the similes above cited” (of a -mane or bunch of sea-weed), the paddles would be out of -sight; and the long eddy and wake created by the propelling -action of the tail would account for the idea of a long -serpentine body, at least for this idea occurring to one -“looking at the strange phenomenon with a sea-serpent in his -mind’s eye.” “It is very probable that not one on board -the <i>Dædalus</i> ever before beheld a gigantic seal freely swimming -in the open ocean.” The excitement produced by the -strange spectacle, and the recollection of “old Pontoppidan’s -sea-serpent with the mane,” would suffice, Professor Owen -considered, to account for the metamorphosis of a sea-elephant -into a maned sea-serpent.</p> - -<p>This was not the whole of Professor Owen’s argument; -but it may be well to pause here, to consider the corrections -immediately made by Captain M’Quhæ; it may be noticed, -first, that Professor Owen’s argument seems sufficiently to -dispose of the belief that the creature really was a sea-serpent, -or any cold-blooded reptile. And this view of the -matter has been confirmed by later observations. But few, -I imagine, can readily accept the belief that Captain M’Quhæ -and his officers had mistaken a sea-elephant for a creature -such as they describe and picture. To begin with, although -it might be probable enough that no one on board the -<i>Dædalus</i> had ever seen a gigantic seal freely swimming in -the open ocean—a sight which Professor Owen himself had -certainly never seen—yet we can hardly suppose they would -not have known a sea-elephant under such circumstances. -Even if they had never seen a sea-elephant at all, they would -surely know what such an animal is like. No one could -mistake a sea-elephant for any other living creature, even -though his acquaintance with the animal were limited to -museum specimens or pictures in books. The supposition -that the entire animal, that is, its entire length, should be -mistaken for 30 or 40 feet of the length of a serpentine neck,<span class="pagenum"><a id="Page_221">221</a></span> -seems, in my judgment, as startling as the ingenious theory -thrown out by some naturalists when they first heard of the -giraffe—to the effect that some one of lively imagination -had mistaken the entire body of a short-horned antelope for -the neck of a much larger animal!</p> - -<p>Captain M’Quhæ immediately replied:—“I assert that -neither was it a common seal nor a sea-elephant; its great -length and its totally different physiognomy precluding the -possibility of its being a <i>Phoca</i> of any species. The head -was flat, and not a capacious vaulted cranium; nor had it a -stiff, inflexible trunk—a conclusion to which Professor Owen -has jumped, most certainly not justified by my simple statement, -that ‘no portion of the 60 feet seen by us was used -in propelling it through the water, either by vertical or horizontal -undulation.’” He explained that the calculation of -the creature’s length was made before, not after, the idea -had been entertained that the animal was a serpent, and that -he and his officers were “too well accustomed to judge of -lengths and breadths of objects in the sea to mistake a real -substance and an actual living body, coolly and dispassionately -contemplated, at so short a distance too, for the ‘eddy -caused by the action of the deeply immersed fins and tail of -a rapidly moving, gigantic seal raising its head above the -water,’ as Professor Owen imagines, in quest of its lost iceberg.” -He next disposed of Owen’s assertion that the idea -of clothing the serpent with a mane had been suggested by -old Pontoppidan’s story, simply because he had never seen -Pontoppidan’s account or heard of Pontoppidan’s sea-serpent, -until he had told his own tale in London. Finally, he -added, “I deny the existence of excitement, or the possibility -of optical illusion. I adhere to the statement as to -form, colour, and dimensions, contained in my report to the -Admiralty.”</p> - -<p>A narrative which appeared in the <cite>Times</cite> early in 1849 -must be referred to in this place, as not being readily -explicable by Professor Owen’s hypothesis. It was written by -Mr. R. Davidson, superintending surgeon, Najpore Subsidiary<span class="pagenum"><a id="Page_222">222</a></span> -Force Kamptee, and was to the following effect (I abridge -it considerably):—When at a considerable distance south-west -of the Cape of Good Hope, Mr. Davidson, Captain -Petrie, of the <i>Royal Saxon</i>, a steerage passenger, and the -man at the wheel, saw “an animal of which no more correct -description could be given than that by Captain M’Quhæ. -It passed within 35 yards of the ship, without altering its -course in the least; but as it came right abreast of us it -slowly turned its head towards us.” About one-third of the -upper part of its body was above water, “in nearly its whole -length; and we could see the water curling up on its breast -as it moved along, but by what means it moved we could -not perceive.” They <em>saw this creature in its whole length</em> -with the exception of a small portion of the tail which was -under water; and by comparing its length with that of the -<i>Royal Saxon</i>, 600 feet, when exactly alongside in passing, -they calculated it to be in length as well as in other dimensions -greater than the animal described by Captain M’Quhæ.</p> - -<p>In the year 1852 two statements were made, one by -Captain Steele, 9th Lancers, the other by one of the officers -of the ship <i>Barham</i> (India merchantman), to the effect that -an animal of a serpentine appearance had been seen about -500 yards from that ship (in longitude 40° E. and 37° 16´ S., -that is, east of the south-eastern corner of Africa). “We -saw him,” said the former, “about 16 or 20 feet out of the -water, and he <em>spouted</em> a long way from his head”—that is, -I suppose, he spouted to some distance, not, as the words -really imply, at a part of his neck far removed from the head. -“Down his back he had a crest like a cock’s comb, and was -going very slowly through the water, but left a wake of about -50 or 60 feet, as if dragging a long body after him. The -captain put the ship off her course to run down to him, but -as we approached him he went down. His colour was green -with light spots. He was seen by every one on board.” -The other witness gives a similar account, adding that the -creature kept moving his head up and down, and was -surrounded by hundreds of birds. “We at first thought it<span class="pagenum"><a id="Page_223">223</a></span> -was a dead whale.... When we were within 100 -yards he slowly sank into the depths of the sea; while we -were at dinner he was seen again.” Mr. Alfred Newton, -the well-known naturalist, guarantees his personal acquaintance -with one of the recipients of the letters just quoted -from. But such a guarantee is, of course, no sufficient -guarantee of the authenticity of the narrative. Even if the -narrative be accepted, the case seems a very doubtful one. -The birds form a suspicious element in the story. Why -should birds cluster around a living sea creature? It seems -to me probable that the sea-weed theory, presently to be -noticed, gives the best explanation of this case. Possibly -some great aggregation of sea-weed was there, in which were -entangled divers objects desirable to birds and to fishes. -These last may have dragged the mass under water when -the ship approached, being perhaps more or less entangled -in it—and it floated up again afterwards. The spouting -may have been simply the play of water over the part mistaken -for the head.</p> - -<p>The sea-weed theory of the sea-serpent was broached in -February, 1849, and supported by a narrative not unlike the -last. When the British ship <i>Brazilian</i> was becalmed almost -exactly in the spot where M’Quhæ had seen his monster, -Mr. Herriman, the commander, perceived something right -abeam, about half a mile to the westward, “stretched along -the water to the length of about 25 or 30 feet, and perceptibly -moving from the ship with a steady, sinuous motion. -The head, which seemed to be lifted several feet above the -waters, had something resembling a mane, running down to -the floating portion, and within about 6 feet of the tail it -forked out into a sort of double fin.” Mr. Herriman, his -first mate, Mr. Long, and several of the passengers, after -surveying the object for some time, came to the unanimous -conclusion that it must be the sea-serpent seen by Captain -M’Quhæ. “As the <i>Brazilian</i> was making no headway, Mr. -Herriman, determining to bring all doubts to an issue, had -a boat lowered down, and taking two hands on board,<span class="pagenum"><a id="Page_224">224</a></span> -together with Mr. Boyd, of Peterhead, near Aberdeen, one -of the passengers, who acted as steersman under the direction -of the captain, they approached the monster, Captain Herriman -standing on the bow of the boat, armed with a harpoon -to commence the onslaught. The combat, however, was -not attended with the danger which those on board apprehended; -for on coming close to the object it was found to -be nothing more than an immense piece of sea-weed, -evidently detached from a coral reef and drifting with the -current, which sets constantly to the westward in this latitude, -and which, together with the swell left by the subsidence of -the gale, gave it the sinuous, snake-like motion.”</p> - -<p>A statement was published by Captain Harrington in the -<cite>Times</cite> of February, 1858, to the effect that from his ship -<i>Castilian</i>, then distant ten miles from the north-east end of -St. Helena, he and his officers had seen a huge marine -animal within 20 yards of the ship; that it disappeared for -about half a minute, and then made its appearance in the -same manner again, showing distinctly its neck and head -about 10 or 12 feet out of the water. “Its head was shaped -like a long nun-buoy,” proceeds Captain Harrington, “and -I suppose the diameter to have been 7 or 8 feet in the -largest part, with a kind of scroll, or tuft, of loose skin -encircling it about 2 feet from the top; the water was discoloured -for several hundred feet from its head.... -From what we saw from the deck, we conclude that it must -have been over 200 feet long. The boatswain and several -of the crew who observed it from the top-gallant forecastle,<a id="FNanchor_26" href="#Footnote_26" class="fnanchor">26</a> -(query, cross-trees?) state that it was more than double the -length of the ship, in which case it must have been 500 feet. -Be that as it may, I am convinced that it belonged to the -serpent tribe; it was of a dark colour about the head, and -was covered with several white spots.”</p> - -<p>This immediately called out a statement from Captain F.<span class="pagenum"><a id="Page_225">225</a></span> -Smith, of the ship <i>Pekin</i>, that on December 28, not far from -the place where the <i>Dædalus</i> had encountered the supposed -sea-serpent, he had seen, at a distance of about half a mile, -a creature which was declared by all hands to be the great -sea-serpent, but proved eventually to be a piece of gigantic -sea-weed. “I have no doubt,” he says, that the great sea-serpent -seen from the <i>Dædalus</i> “was a piece of the same -weed.”</p> - -<p>It will have been noticed that the sea-weed sea-serpents, -seen by Captain F. Smith and by Captain Herriman, were -both at a distance of half a mile, at which distance one can -readily understand that a piece of sea-weed might be mistaken -for a living creature. This is rather different from the -case of the <i>Dædalus</i> sea-serpent, which passed so near that -had it been a man of the captain’s acquaintance he could -have recognized that man’s features with the naked eye. -The case, too, of Captain Harrington’s sea-serpent, seen -within 20 yards of the <i>Castilian</i>, can hardly be compared -to those cases in which sea-weed, more than 800 yards from -the ship, was mistaken for a living animal. An officer of the -<i>Dædalus</i> thus disposed of Captain Smith’s imputation:—“The -object seen from the ship was beyond all question a -living animal, moving rapidly through the water against a -cross sea, and within five points of a fresh breeze, with such -velocity that the water was surging against its chest as it -passed along at a rate probably of ten miles per hour. -Captain M’Quhæ’s first impulse was to tack in pursuit, but -he reflected that we could neither lay up for it nor overhaul -it in speed. There was nothing to be done, therefore, but -to observe it as accurately as we could with our glasses as it -came up under our lee quarter and passed away to windward, -being at its nearest position not more than 200 yards -from us; <em>the eye, the mouth, the nostril, the colour, and the -form, all being most distinctly visible to us</em>.... My impression -was that it was rather of a lizard than a serpentine -character, as its movement was steady and uniform, <em>as if -propelled by fins</em>, not by any undulatory power.”</p> - -<p><span class="pagenum"><a id="Page_226">226</a></span> -But all the evidence heretofore obtained respecting the -sea-serpent, although regarded by many naturalists, Gosse, -Newman, Wilson, and others, as demonstrating the existence -of some as yet unclassified monster of the deep, seems altogether -indecisive by comparison with that which has recently -been given by the captain, mates, and crew of the ship -<i>Pauline</i>. In this case, assuredly, we have not to deal with -a mass of sea-weed, the floating trunk of a tree, a sea-elephant -hastening to his home amid the icebergs, or with any of the -other more or less ingenious explanations of observations -previously made. We have either the case of an actual -living animal, monstrous, fierce, and carnivorous, or else -the five men who deposed on oath to the stated facts devised -the story between them, and wilfully perjured themselves for -no conceivable purpose—that, too, not as men have been -known to perjure themselves under the belief that none -could know of their infamy, but with the certainty on the -part of each that four others (any one of whom might one -day shame him and the rest by confessing) knew the real -facts of the case.</p> - -<p>The story of the <i>Pauline</i> sea-serpent ran simply as follows, -as attested at the Liverpool police-court:—“We, the undersigned, -captain, officers, and crew of the bark <i>Pauline</i>, of -London, do solemnly and sincerely declare, that on July 8, -1875, in latitude 5° 13´ S., longitude 35° W., we observed -three large sperm whales, and one of them was gripped -round the body with two turns of what appeared to be a huge -serpent. The head and tail appeared to have a length -beyond the coils of about 30 feet, and its girth 8 or 9 feet. -The serpent whirled its victim round and round for about -fifteen minutes, and then suddenly dragged the whale to the -bottom, head first.—George Drevat, master; Horatio -Thompson, chief mate; John H. Landells, second mate; -William Lewarn, steward; Owen Baker, A.B. Again on the -13th July a similar serpent was seen about 200 yards off, -shooting itself along the surface, head and neck being out of -the water several feet. This was seen only by the captain<span class="pagenum"><a id="Page_227">227</a></span> -and an ordinary seaman.—George Drevat. A few moments -afterwards it was seen elevated some 60 feet perpendicularly -in the air by the chief officer and two seamen, whose signatures -are affixed.—Horatio Thompson, Owen Baker, -William Lewarn.”</p> - -<p>The usual length of the cachalot or sperm whale is about -70 feet, and its girth about 50 feet. If we assign to the -unfortunate whale which was captured on this occasion, a -length of only 50 feet, and a girth of only 35 feet, we should -still have for the entire length of the supposed serpent about -100 feet. This can hardly exceed the truth, since the three -whales are called large sperm whales. With a length of 100 -feet and a girth of about 9 feet, however, a serpent would -have no chance in an attempt to capture a sperm whale 50 -feet long and 35 feet in girth, for the simple reason that the -whale would be a good deal heavier than its opponent. In -a contest in open sea, where one animal seeks to capture -another bodily, weight is all-important. We can hardly -suppose the whale could be so compassed by the coils of -his enemy as to be rendered powerless; in fact, the contest -lasted fifteen minutes, during the whole of which time the -so-called serpent was whirling its victim round, though more -massive than itself, through the water. On the whole, it -seems reasonable to conclude—in fact, the opinion is almost -forced upon us—that besides the serpentine portion of its -bulk, which was revealed to view, the creature, thus whirling -round a large sperm whale, had a massive concealed body, -provided with propelling paddles of enormous power. <em>These</em> -were at work all the time the struggle went on, enabling the -creature to whirl round its enemy easily, whereas a serpentine -form, with two-thirds of its length, at least, coiled close round -another body, would have had no propulsive power left, or -very little, in the remaining 30 feet of its length, including -both the head and tail ends beyond the coils. Such a -creature as an enaliosaurus <em>could</em> no doubt have done what -a serpent of twice the supposed length would have attempted -in vain—viz., dragged down into the depths of the sea the -mighty bulk of a cachalot whale.</p> - -<p><span class="pagenum"><a id="Page_228">228</a></span> -When all the evidence is carefully weighed, we appear -led to the conclusion that at least one large marine animal -exists which has not as yet been classified among the known -species of the present era. It would appear that this -animal has certainly a serpentine neck, and a head small -compared with its body, but large compared with the -diameter of the neck. It is probably an air-breather and -warm-blooded, and certainly carnivorous. Its propulsive -power is great and apparently independent of undulations -of its body, wherefore it presumably has powerful concealed -paddles. All these circumstances correspond with the -belief that it is a modern representative of the long-neck -plesiosaurians of the great secondary or mesozoic era, a -member of that strange family of animals whose figure has -been compared to that which would be formed by drawing a -serpent through the body of a sea-turtle.</p> - -<p>Against this view sundry objections have been raised, -which must now be briefly considered.</p> - -<p>In the first place, Professor Owen pointed out that the -sea-saurians of the secondary period have been replaced in -the tertiary and present seas by the whales and allied races. -No whales are found in the secondary strata, no saurians -in the tertiary. “It seems to me less probable,” he says, -“that no part of the carcase of such reptiles should have -ever been discovered in a recent unfossilized state, than -that men should have been deceived by a cursory view of -a partly submerged and rapidly moving animal which might -only be strange to themselves. In other words, I regard -the negative evidence from the utter absence of any of the -recent remains of great sea-serpents, krakens, or enaliosauria, -as stronger against their actual existence, than the positive -statements which have hitherto weighed with the public -mind in favour of their existence. A larger body of evidence -from eye-witnesses might be got together in proof of -ghosts than of the sea-serpent.”</p> - -<p>To this it has been replied that genera are now known -to exist, as the <i>Chimæra</i>, the long-necked river tortoise, and<span class="pagenum"><a id="Page_229">229</a></span> -the iguana, which are closely related to forms which existed -in the secondary era, while no traces have been found of -them in any of the intermediate or tertiary strata. The -chimæra is a case precisely analogous to the supposed case -of the enaliosaurus, for the chimæra is but rarely seen, like -the supposed enaliosaurus, is found in the same and absent -from the same fossiliferous strata. Agassiz is quoted in the -<cite>Zoologist</cite>, page 2395, as saying that it would be in precise conformity -with analogy that such an animal as the enaliosaurus -should exist in the American seas, as he had found numerous -instances in which the fossil forms of the Old World were -represented by living types in the New. In close conformity -with this opinion is a statement made by Captain -the Hon. George Hope, that when in the British ship <i>Fly</i>, -in the Gulf of California, the sea being perfectly calm and -transparent, he saw at the bottom a large marine animal, -with the head and general figure of an alligator, but the -neck much longer, and with four large paddles instead of -legs. Here, then, unless this officer was altogether deceived, -which seems quite unlikely under the circumstances, -was a veritable enaliosaurus, though of a far smaller species, -probably, than the creature mistaken for a sea-serpent.</p> - -<p>As for the absence of remains, Mr. Darwin has pointed -out that the fossils we possess are but fragments accidentally -preserved by favouring circumstances in an almost total -wreck. We have many instances of existent creatures, even -such as would have a far better chance of floating after -death, and so getting stranded where their bones might be -found, which have left no trace of their existence. A whale -possessing two dorsal fins was said to have been seen by -Smaltz, a Sicilian naturalist; but the statement was rejected, -until a shoal of these whales were seen by two eminent -French zoologists, MM. Quoy and Gaimard. No carcase, -skeleton, or bone of this whale has ever been discovered. -For seventeen hours a ship, in which Mr. Gosse was travelling -to Jamaica, was surrounded by a species of whale -never before noticed—30 feet long, black above and<span class="pagenum"><a id="Page_230">230</a></span> -white beneath, with swimming paws white on the upper -surface. Here, he says, was “a whale of large size, occurring -in great numbers in the North Atlantic, which on no -other occasion has fallen under scientific observation. The -toothless whale of Havre, a species actually inhabiting the -British Channel, is only known from a single specimen -accidentally stranded on the French coast; and another -whale, also British, is known only from a single specimen -cast ashore on the Elgin roast, and there seen and described -by the naturalist Sowerby.</p> - -<p>Dr. Andrew Wilson, in an interesting paper, in which he -maintains that sea-serpent tales are not to be treated with -derision, but are worthy of serious consideration, “supported -as they are by zoological science, and in the actual details -of the case by evidence as trustworthy in many cases as that -received in our courts of law,” expresses the opinion that plesiosauri -and ichthyosauri have been unnecessarily disinterred -to do duty for the sea-serpents. But he offers as an alternative -only the ribbon-fish; and though some of these may -attain enormous dimensions, yet we have seen that some of -the accounts of the supposed sea-serpent, and especially -the latest narrative by the captain and crew of the <i>Pauline</i>, -cannot possibly be explained by any creature so flat and -relatively so feeble as the ribbon-fish.</p> - -<p>On the whole, it appears to me that a very strong case -has been made out for the enaliosaurian, or serpent-turtle, -theory of the so-called sea-serpent.</p> - -<p>One of the ribbon-fish mentioned by Dr. Wilson, which -was captured, and measured more than 60 feet in length, -might however fairly take its place among strange sea creatures. -I scarcely know whether to add to the number a -monstrous animal like a tadpole, or even more perhaps like a -gigantic skate, 200 feet in length, said to have been seen in -the Malacca Straits by Captain Webster and Surgeon Anderson, -of the ship <i>Nestor</i>. Perhaps, indeed, this monster, mistaken -in the first instance for a shoal, but presently found -to be travelling along at the rate of about ten knots an hour,<span class="pagenum"><a id="Page_231">231</a></span> -better deserves to be called a strange sea creature even than -any of those which have been dealt with in the preceding -pages. But the only account I have yet seen of Captain -Webster’s statement, and Mr. Anderson’s corroboration, -appeared in an American newspaper; and though the story -is exceedingly well authenticated if the newspaper account -of the matter is true, it would not be at all a new feature in -American journalism if not only the story itself, but all the -alleged circumstances of its narration, should in the long -run prove to be pure invention.</p> - -<hr /> - -<p><span class="pagenum"><a id="Page_232">232</a></span></p> - -<div class="chapter"> -<h2><a id="ON_SOME_MARVELS_IN_TELEGRAPHY"></a><i>ON SOME MARVELS IN TELEGRAPHY.</i></h2> -</div> - -<p class="in0">Within the last few years Electric Telegraphy has received -some developments which seem wonderful even by comparison -with those other wonders which had before been -achieved by this method of communication. In reality, all -the marvels of electric telegraphy are involved, so to speak, -in the great marvel of electricity itself, a phenomenon as yet -utterly beyond the interpretation of physicists, though not -more so than its fellow marvels, light and heat. We may, -indeed, draw a comparison between some of the most -wonderful results which have recently been achieved by the -study of heat and light and those effected in the application -of electricity to telegraphy. It is as startling to those -unfamiliar with the characteristics of light, or rather with -certain peculiarities resulting from these characteristics, to be -told that an astronomer can tell whether there is water in the -air of Mars or Venus, or iron vapour in the atmosphere of -Aldebaran or Betelgeux, as it is to those unfamiliar with the -characteristics of electricity, or with the results obtained in -consequence of these characteristics, to be told that a written -message can be copied by telegraph, a map or diagram -reproduced, or, most wonderful of all, a musical air correctly -repeated, or a verbal message made verbally audible. -Telegraphic marvels such as these bear to the original<span class="pagenum"><a id="Page_233">233</a></span> -marvel of mere telegraphic communication, somewhat the -same relation which the marvels of spectroscopic analysis as -applied to the celestial orbs bear to that older marvel, the -telescopic scrutiny of those bodies. In each case, also, -there lies at the back of all these marvels a greater marvel -yet—electricity in the one case, light in the other.</p> - -<p>I propose in this essay to sketch the principles on which -some of the more recent wonders of telegraphic communication -depend. I do not intend to describe at any length the -actual details or construction of the various instruments -employed. Precisely as the principles of spectroscopic -analysis can be made clear to the general reader without the -examination of the peculiarities of spectroscopic instruments, -so can the methods and principles of telegraphic communication -be understood without examining instrumental details. -In fact, it may be questioned whether general -explanations are not in such cases more useful than more -detailed ones, seeing that these must of necessity be insufficient -for a student who requires to know the subject -practically in all its details, while they deter the general -reader by technicalities in which he cannot be expected to -take any interest. If it be asked, whether I myself, who -undertake to explain the principles of certain methods of -telegraphic communication, have examined <em>practically</em> the -actual instrumental working of these methods, I answer -frankly that I have not done so. As some sort of proof, -however, that without such practical familiarity with working -details the principles of the construction of instruments may -be thoroughly understood, I may remind the reader (see p. <a href="#Page_96">96</a>) -that the first spectroscopic battery I ever looked through—one -in which the dispersive power before obtained in such -instruments had been practically doubled—was of my own -invention, constructed (with a slight mechanical modification) -by Mr. Browning, and applied at once successfully to the -study of the sun by Mr. Huggins, in whose observatory I saw -through this instrument the solar spectrum extended to a -length which, could it all have been seen at once, would have<span class="pagenum"><a id="Page_234">234</a></span> -equalled many feet.<a id="FNanchor_27" href="#Footnote_27" class="fnanchor">27</a> On the other hand, it is possible to -have a considerable practical experience of scientific instruments -without sound knowledge of the principles of their -construction; insomuch that instances have been known in -which men who have effected important discoveries by the -use of some scientific instrument, have afterwards obtained -their first clear conception of the principles of its construction -from a popular description.</p> - -<p>It may be well to consider, though briefly, some of the -methods of communication which were employed before -the electric telegraph was invented. Some of the methods -of electric telegraphy have their antitypes, so to speak, in -methods of telegraphy used ages before the application of -electricity. The earliest employment of telegraphy was probably -in signalling the approach of invading armies by -beacon fires. The use of this method must have been well -known in the time of Jeremiah, since he warns the Benjamites -“to set up a sign of fire in Beth-haccerem,” because -“evil appeareth out of the north and great destruction.” -Later, instead of the simple beacon fire, combinations were -used. Thus, by an Act of the Scottish Parliament in 1455, -the blazing of one bale indicated the probable approach -of the English, two bales that they were coming indeed, -and four bales blazing beside each other that they were in -great force. The smoke of beacon fires served as signals -by day, but not so effectively, except under very favourable -atmospheric conditions.</p> - -<p>Torches held in the hand, waved, depressed, and so -forth, were anciently used in military signalling at night; -while in the day-time boards of various figures in different -positions indicated either different messages or different -letters, as might be pre-arranged.</p> - -<p>Hooke communicated to the Royal Society in 1684 a -paper describing a method of “communicating one’s mind<span class="pagenum"><a id="Page_235">235</a></span> -at great distances.” The letters were represented by various -combinations of straight lines, which might be agreed upon -previously if secrecy were desired, otherwise the same forms -might represent constantly the same letters. With four -straight planks any letter of this alphabet could be formed -as wanted, and being then run out on a framework (resembling -a gallows in Hooke’s picture), could be seen from a -distant station. Two curved beams, combined in various -ways, served for arbitrary signals.</p> - -<p>Chappe, in 1793, devised an improvement on this in -what was called the T telegraph. An upright post supported -a cross-bar (the top of the T), at each end of which -were the short dependent beams, making the figure a complete -Roman capital T. The horizontal bar as first used -could be worked by ropes within the telegraph-house, so as -to be inclined either to right or left. It thus had three -positions. Each dependent beam could be worked (also -from within the house) so as to turn upwards, horizontally, -or downwards (regarding the top bar of the T as horizontal), -thus having also three positions. It is easily seen that, -since each position of one short beam could be combined -with each position of the other, the two together would -present three times three arrangements, or nine in all; and -as these nine could be given with the cross-bar in any one -of its three positions, there were in all twenty-seven possible -positions. M. Chappe used an alphabet of only sixteen -letters, so that all messages could readily be communicated -by this telegraph. For shorter distances, indeed, and in all -later uses of Chappe’s telegraph, the short beams could be -used in intermediate positions, by which 256 different signals -could be formed. Such telegraphs were employed on a -line beginning at the Louvre and proceeding by Montmartre -to Lisle, by which communications were conveyed from the -Committee of Public Welfare to the armies in the Low -Countries. Telescopes were used at each station. Barrère -stated, in an address to the Convention on August 17, 1794, -that the news of the recapture of Lisle had been sent by<span class="pagenum"><a id="Page_236">236</a></span> -this line of communication to Paris in one hour after the -French troops had entered that city. Thus the message -was conveyed at the rate of more than 120 miles per hour.</p> - -<p>Various other devices were suggested and employed -during the first half of the present century. The semaphores -still used in railway signalling illustrate the general -form which most of these methods assumed. An upright, -with two arms, each capable of assuming six distinct positions -(excluding the upright position), would give forty-eight -different signals; thus each would give six signals alone, -or twelve for the pair, and each of the six signals of one -combined with each of the six signals of the other, would -give thirty-six signals, making forty-eight in all. This number -suffices to express the letters of the alphabet (twenty-five -only are needed), the Arabic numerals, and thirteen -arbitrary signals.</p> - -<p>The progress of improvement in such methods of signalling -promised to be rapid, before the invention of the -electric telegraph, or rather, before it was shown how the -principle of the electric telegraph could be put practically -into operation. We have seen that they were capable of -transmitting messages with considerable rapidity, more than -twice as fast as we could now send a written message by -express train. But they were rough and imperfect. They -were all, also, exposed to one serious defect. In thick -weather they became useless. Sometimes, at the very time -when it was most important that messages should be quickly -transmitted, fog interrupted the signalling. Sir J. Barrow -relates that during the Peninsular War grave anxiety was -occasioned for several hours by the interruption of a message -from Plymouth, really intended to convey news of a -victory. The words transmitted were, “Wellington defeated;” -the message of which these words formed the -beginning was: “Wellington defeated the French at,” etc. -As Barrow remarks, if the message had run, “French defeated -at,” etc., the interruption of the message would have -been of less consequence.</p> - -<p><span class="pagenum"><a id="Page_237">237</a></span> -Although the employment of electricity as a means of -communicating at a distance was suggested before the end -of the last century, in fact, so far back as 1774, the idea -has only been worked out during the last forty-two years. It -is curious indeed to note that until the middle of the present -century the word “telegraph,” which is now always understood -as equivalent to electric telegraph, unless the contrary -is expressed, was commonly understood to refer to semaphore -signalling,<a id="FNanchor_28" href="#Footnote_28" class="fnanchor">28</a> unless the word “electric” were added.</p> - -<p>The general principle underlying all systems of telegraphic -communication by electricity is very commonly -misunderstood. The idea seems to prevail that electricity -can be sent out along a wire to any place where some suitable -arrangement has been made to receive it. In one sense -this is correct. But the fact that the electricity has to make -a circuit, returning to the place from which it is transmitted, -seems not generally understood. Yet, unless this is understood, -the principle, even the possibility, of electric communication -is not recognized.</p> - -<p>Let us, at the outset, clearly understand the nature of -electric communication.</p> - -<p>In a variety of ways, a certain property called electricity -can be excited in all bodies, but more readily in some than -in others. This property presents itself in two forms, which -are called positive and negative electricity, words which we -may conveniently use, but which must not be regarded as -representing any real knowledge of the distinction between -these two kinds of electricity. In fact, let it be remembered -throughout, that we do not in the least know what electricity<span class="pagenum"><a id="Page_238">238</a></span> -is; we only know certain of the phenomena which -it produces. Any body which has become charged with -electricity, either positive or negative, will part with its -charge to bodies in a neutral condition, or charged with the -opposite electricity (negative or positive). But the transference -is made much more readily to some substances than -to others—so slowly, indeed, to some, that in ordinary -experiments the transference may be regarded as not taking -place at all. Substances of the former kind are called good -conductors of electricity; those which receive the transfer -of electricity less readily are said to be bad conductors; -and those which scarcely receive it at all are called insulating -substances. The reader must not confound the -quality I am here speaking of with readiness to become -charged with electricity. On the contrary, the bodies which -most freely receive and transmit electricity are least readily -charged with electricity, while insulating substances are -readily electrified. Glass is an insulator, but if glass is -briskly rubbed with silk it becomes charged (or rather, the -part rubbed becomes charged) with positive electricity, -formerly called <em>vitreous</em> electricity for this reason; and -again, if wax or resin, which are both good insulators, be -rubbed with cloth or flannel, the part rubbed becomes -charged with negative, formerly called <em>resinous</em>, electricity.</p> - -<p>Electricity, then, positive or negative, however generated, -passes freely along conducting substances, but is stopped -by an insulating body, just as light passes through transparent -substances, but is stopped by an opaque body. -Moreover, electricity may be made to pass to any distance -along conducting bodies suitably insulated. Thus, it might -seem that we have here the problem of distant communication -solved. In fact, the first suggestion of the use of electricity -in telegraphy was based on this property. When a -charge of electricity has been obtained by the use of an -ordinary electrical machine, this charge can be drawn off at -a distant point, if a conducting channel properly insulated -connects that point with the bodies (of whatever nature)<span class="pagenum"><a id="Page_239">239</a></span> -which have been charged with electricity. In 1747, Dr. -Watson exhibited electrical effects from the discharges of -Leyden jars (vessels suitably constructed to receive and -retain electricity) at a distance of two miles from the electrical -machine. In 1774, Le Sage proposed that by means -of wires the electricity developed by an electrical machine -should be transmitted by insulated wires to a point where -an electroscope, or instrument for indicating the presence of -electricity, should, by its movements, mark the letters of the -alphabet, one wire being provided for each letter. In 1798 -Béthencourt repeated Watson’s experiment, increasing the distance -to twenty-seven miles, the extremities of his line of communication -being at Madrid and Aranjuez. (Guillemin, by -the way, in his “Applications of the Physical Forces,” passes -over Watson’s experiment; in fact, throughout his chapters -on the electric telegraph, the steam-engine, and other subjects, -he seems desirous of conveying as far as possible the -impression that all the great advances of modern science -had their origin in Paris and its neighbourhood.)</p> - -<p>From Watson’s time until 1823 attempts were made in -this country and on the Continent to make the electrical -machine serve as the means of telegraphic communication. -All the familiar phenomena of the lecture-room have been -suggested as signals. The motion of pith balls, the electric -spark, the perforation of paper by the spark, the discharge of -sparks on a fulminating pane (a glass sheet on which pieces -of tinfoil are suitably arranged, so that sparks passing from -one to another form various figures or devices), and other -phenomena, were proposed and employed experimentally. -But practically these methods were not effectual. The -familiar phenomenon of the electric spark explains the cause -of failure. The spark indicates the passage of electricity -across an insulating medium—dry air—when a good conductor -approaches within a certain distance of the charged -body. The greater the charge of electricity, the greater is -the distance over which the electricity will thus make its -escape. Insulation, then, for many miles of wire, and still<span class="pagenum"><a id="Page_240">240</a></span> -more for a complete system of communication such as we -now have, was hopeless, so long as frictional electricity was -employed, or considerable electrical intensity required.</p> - -<p>We have now to consider how galvanic electricity, discovered -in 1790, was rendered available for telegraphic -communication. In the first place, let us consider what -galvanic or voltaic electricity is.</p> - -<p>I have said that electricity can be generated in many -ways. It may be said, indeed, that every change in the -condition of a substance, whether from mechanical causes, -as, for instance, a blow, a series of small blows, friction, and -so forth, or from change of temperature, moisture, and the -like, or from the action of light, or from chemical processes, -results in the development of more or less electricity.</p> - -<p>When a plate of metal is placed in a vessel containing -some acid (diluted) which acts chemically on the metal, this -action generates negative electricity, which passes away as -it is generated. But if a plate of a different metal, either -not chemically affected by the acid or less affected than the -former, be placed in the dilute acid, the two plates being -only partially immersed and not in contact, then, when a -wire is carried from one plate to the other, the excess of -positive electricity in the plate least affected by the acid is -conveyed to the other, or, in effect, discharged; the chemical -action, however, continues, or rather is markedly increased, -fresh electricity is generated, and the excess of positive -electricity in the plate least affected is constantly discharged. -Thus, along the wire connecting the two metals a current of -electricity passes from the metal least affected to the metal -most affected; a current of negative electricity passes in a -contrary direction in the dilute acid.</p> - -<p>I have spoken here of currents passing along the wire -and in the acid, and shall have occasion hereafter to speak -of the plate of metal least affected as the positive pole, this -plate being regarded, in this case, as a source whence a -current of positive electricity flows along the wire connection -to the other plate, which is called the negative pole. But I<span class="pagenum"><a id="Page_241">241</a></span> -must remind the reader that this is only a convenient way -of expressing the fact that the wire assumes a certain condition -when it connects two such plates, and is capable of -producing certain effects. Whether in reality any process is -taking place which can be justly compared to the flow of a -current one way or the other, or whether a negative current -flows along the circuit one way, while the positive current -flows the other way, are questions still unanswered. We -need not here enter into them, however. In fact, very little -is known about these points. Nor need we consider here -the various ways in which many pairs of plates such as I -have described can be combined in many vessels of dilute -acid to strengthen the current. Let it simply be noted that -such a combination is called a battery; that when the extreme -plates of opposite kinds are connected by a wire, a -current of electricity passes along the wire from the extreme -plate of that metal which is least affected, forming the positive -pole, to the other extreme plate of that metal which is -most affected and forms the negative pole. The metals -commonly employed are zinc and copper, the former being -the one most affected by the action of the dilute acid, usually -sulphuric acid. But it must here be mentioned that the -chemical process, affecting both metals, but one chiefly, -would soon render a battery of the kind described useless; -wherefore arrangements are made in various ways for maintaining -the efficiency of the dilute acid and of the metallic -plates, especially the copper: for the action of the acid on -the zinc tends, otherwise, to form on the copper a deposit of -zinc. I need not describe the various arrangements for -forming what are called constant batteries, as Daniell’s, -Grove’s, Bunsen’s, and others. Let it be understood that, -instead of a current which would rapidly grow weaker and -weaker, these batteries give a steady current for a considerable -time. Without this, as will presently be seen, telegraphic -communication would be impossible.</p> - -<p>We have, then, in a galvanic battery a steady source of -electricity. This electricity is of low intensity, incompetent<span class="pagenum"><a id="Page_242">242</a></span> -to produce the more striking phenomena of frictional electricity. -Let us, however, consider how it would operate at -a distance.</p> - -<p>The current will pass along any length of conducting -substance properly insulated. Suppose, then, an insulated -wire passes from the positive pole of a battery at a station -<span class="smcap smaller">A</span> to a station <span class="smcap smaller">B</span>, and thence back to the negative pole at -the station <span class="smcap smaller">A</span>. Then the current passes along it, and this -can be indicated at <span class="smcap smaller">B</span> by some action such as electricity of -low intensity can produce. If now the continuity of the -wire be interrupted close by the positive pole at <span class="smcap smaller">A</span>, the current -ceases and the action is no longer produced. The -observer at <span class="smcap smaller">B</span> knows then that the continuity of the wire has -been interrupted; he has been, in fact, signalled to that -effect.</p> - -<p>But, as I have said, the electrical phenomena which can -be produced by the current along a wire connecting the -positive and negative poles of a galvanic battery are not -striking. They do not afford effective signals when the -distance traversed is very great and the battery not exceptionally -strong. Thus, at first, galvanic electricity was not -more successful in practice than frictional electricity.</p> - -<p>It was not until the effect of the galvanic current on the -magnetic needle had been discovered that electricity became -practically available in telegraphy.</p> - -<p>Oersted discovered in 1820 that a magnetic needle poised -horizontally is deflected when the galvanic current passes -above it (parallel to the needle’s length) or below it. If the -current passes above it, the north end of the needle turns -towards the east when the current travels from north to -south, but towards the west when the current travels from -south to north; on the other hand, if the current passes -below the needle, the north end turns towards the west when -the current travels from south to north, and towards the east -when the current travels from north to south. The deflection -will be greater or less according to the power of the current. It -would be very slight indeed in the case of a needle, however<span class="pagenum"><a id="Page_243">243</a></span> -delicately poised, above or below which passed a wire conveying -a galvanic current from a distant station. But the -effect can be intensified, as follows:—</p> - -<div id="ip_243" class="figcenter" style="max-width: 25.9375em;"> - <img src="images/i_243.jpg" width="415" height="77" alt="" /> - <div class="caption"><span class="smcap">Fig. 1.</span></div></div> - -<p>Suppose <i>a b c d e f</i> to be a part of the wire from <span class="smcap smaller">A</span> to <span class="smcap smaller">B</span>, -passing above a delicately poised magnetic needle <span class="smcap">N S</span>, along -<i>a b</i> and then below the needle along <i>c d</i>, and then above -again along <i>e f</i> and so to the station <span class="smcap smaller">B</span>. Let a current -traverse the wire in the direction shown by the arrows. Then -<span class="smcap smaller">N</span>, the north end of the needle, is deflected towards the east -by the current passing along <i>a b</i>. But it is also deflected -to the east by the current passing along <i>c d</i>; for this -produces a deflection the reverse of that which would be -produced by a current in the same direction above the -needle—that is, in direction <i>b a</i>, and therefore the same as -that produced by the current along <i>a b</i>. The current along -<i>e f</i> also, of course, produces a deflection of the end <span class="smcap smaller">N</span> towards -the east. All three parts, then, <i>a b</i>, <i>c d</i>, <i>e f</i>, conspire -to increase the deflection of the end <span class="smcap smaller">N</span> towards the east. -If the wire were twisted once again round <span class="smcap">N S</span>, the deflection -would be further increased; and finally, if the wire be coiled -in the way shown in <a href="#ip_243">Fig. 1</a>, but with a great number of -coils, the deflection of the north end towards the east, -almost imperceptible without such coils, will become sufficiently -obvious. If the direction of the current be changed, -the end <span class="smcap smaller">N</span> will be correspondingly deflected towards the -west.</p> - -<p>The needle need not be suspended horizontally. If it -hang vertically, that is, turn freely on a horizontal axis, and -the coil be carried round it as above described, the deflection -of the upper end will be to the right or to the left, -according to the direction of the current. The needle -actually seen, moreover, is not the one acted upon by the<span class="pagenum"><a id="Page_244">244</a></span> -current. This needle is inside the coil; the needle seen turns -on the same axis, which projects through the coil.</p> - -<p>If, then, the observer at the station <span class="smcap smaller">B</span> have a magnetic -needle suitably suspended, round which the wire from the -battery at <span class="smcap smaller">A</span> has been coiled, he can tell by the movement of -the needle whether a current is passing along the wire in -one direction or in the other; while if the needle is at rest he -knows that no current is passing.</p> - -<div id="ip_244" class="figcenter" style="max-width: 30.1875em;"> - <img src="images/i_244.jpg" width="483" height="129" alt="" /> - <div class="caption"><span class="smcap">Fig. 2.</span></div></div> - -<div id="ip_244b" class="figcenter" style="max-width: 30.1875em;"> - <img src="images/i_244a.jpg" width="483" height="127" alt="" /> - <div class="caption"><span class="smcap">Fig. 3.</span></div></div> - -<p>Now suppose that <span class="smcap smaller">P</span> and <span class="smcap smaller">N</span>, <a href="#ip_244">Fig. 2</a>, are the positive and -negative poles of a galvanic battery at <span class="smcap smaller">A</span>, and that a wire passes -from <span class="smcap smaller">P</span> to the station <span class="smcap smaller">B</span>, where it is coiled round a needle -suspended vertically at <i>n</i>, and thence passes to the negative -pole <span class="smcap smaller">N</span>. Let the wire be interrupted at <i>a b</i> and also at <i>c d</i>. -Then no current passes along the wire, and the needle <i>n</i> -remains at rest in a vertical position. Now suppose the -points <i>a b</i> connected by the wire <i>a b</i>, and at the same moment -the points <i>c d</i> connected by the wire <i>c d</i>, then a current -flows along <span class="smcap smaller">P</span> <i>a b</i> to <span class="smcap smaller">B</span>, as shown in <a href="#ip_244">Fig. 2</a>, circuiting the coil -round the needle <i>n</i> and returning by <i>d c</i> to <span class="smcap smaller">N</span>. The upper -end of the needle is deflected to the right while this current -continues to flow; returning to rest when the connection is -broken at <i>a b</i> and <i>c d</i>. Next, let <i>c b</i> and <i>a d</i> be simultaneously<span class="pagenum"><a id="Page_245">245</a></span> -connected as shown by the cross-lines in <a href="#ip_244b">Fig. 3</a>. (It -will be understood that <i>a d</i> and <i>b c</i> do not touch each other -where they cross.) The current will now flow from <span class="smcap smaller">P</span> along -<i>a d</i> to <span class="smcap smaller">B</span>, circuiting round the needle <i>n</i> in a contrary direction -to that in which it flowed in the former case, returning by -<i>b c</i> to <span class="smcap smaller">N</span>. The upper end of the needle is deflected then to -the left while the current continues to flow along this course.</p> - -<p>I need not here describe the mechanical devices by -which the connection at <i>a b</i> and <i>c d</i> can be instantly changed -so that the current may flow either along <i>a b</i> and <i>d c</i>, as in -<a href="#ip_244">Fig. 2</a>, circuiting the needle in one direction, or along <i>a d</i> -and <i>b c</i>, as in <a href="#ip_244b">Fig. 3</a>, circuiting the needle in the other direction. -As I said at the outset, this paper is not intended to -deal with details of construction, only to describe the general -principles of telegraphic communication, and especially those -points which have to be explained in order that recent inventions -may be understood. The reader will see that nothing -can be easier than so to arrange matters that, by turning a -handle, either (1), <i>a b</i> and <i>c d</i> may be connected, or, (2), <i>a d</i> -and <i>c b</i>, or, (3), both lines of communication interrupted. -The mechanism for effecting this is called a <em>commutator</em>.</p> - -<p>Two points remain, however, to be explained: First, <span class="smcap smaller">A</span> -must be a receiving station as well as a transmitting station; -secondly, the wire connecting <span class="smcap smaller">B</span> with <span class="smcap smaller">N</span>, in Figs. 2 and 3, can -be dispensed with, for it is found that if at <span class="smcap smaller">B</span> the wire is -carried down to a large metal plate placed some depth -underground, while the wire at <i>c</i> is carried down to another -plate similarly buried underground, the circuit is completed -even better than along such a return wire as is shown in the -figures. The earth either acts the part of a return wire, or -else, by continually carrying off the electricity, allows the -current to flow continuously along the single wire. We -may compare the current carried along the complete wire -circuit, to water circulating in a pipe extending continuously -from a reservoir to a distance and back again to -the reservoir. Water sucked up continuously at one end -could be carried through the pipe so long as it was continuously<span class="pagenum"><a id="Page_246">246</a></span> -returned to the reservoir at the other; but it could -equally be carried through a pipe extending from that reservoir -to some place where it could communicate with the -open sea—the reservoir itself communicating with the open -sea—an arrangement corresponding to that by which the -return wire is dispensed with, and the current from the wire -received into the earth.</p> - -<p>The discovery that the return wire may be dispensed -with was made by Steinheil in 1837.</p> - -<p>The actual arrangement, then, is in essentials that represented -in <a href="#ip_246">Fig. 4</a>.</p> - -<div id="ip_246" class="figcenter" style="max-width: 35.0625em;"> - <img src="images/i_246.jpg" width="561" height="206" alt="" /> - <div class="caption"><span class="smcap">Fig. 4.</span></div></div> - -<p><span class="smcap smaller">A</span> and <span class="smcap smaller">B</span> are the two stations; <span class="smcap">P N</span> is the battery at <span class="smcap smaller">A</span>, <span class="smcap">P´ N´</span> -the battery at <span class="smcap smaller">B</span>; <span class="smcap">P´ P´</span> are the positive poles, <span class="smcap">N´ N´</span>, the negative -poles. At <i>n</i> is the needle of station <span class="smcap smaller">A</span>, at <i>n´</i> the needle of -station <span class="smcap smaller">B</span>. When the handle of the commutator is in its -mean position—which is supposed to be the case at station -<span class="smcap smaller">B</span>—the points <i>b´ d´</i> are connected with each other, but -neither with <i>a´</i> nor <i>c´</i>; no current, then, passes from <span class="smcap smaller">B</span> to <span class="smcap smaller">A</span>, -but station <span class="smcap smaller">B</span> is in a condition to receive messages. (If <i>b´</i> -and <i>d´</i> were not connected, of course no messages could be -received, since the current from <span class="smcap smaller">A</span> would be stopped at <i>b´</i>—which -does not mean that it would pass round <i>n´</i> to <i>b´</i>, but -that, the passage being stopped at <i>b´</i>, the current would not -flow at all.) When (the commutator at <span class="smcap smaller">B</span> being in its mean -position, or <i>d´ b´</i> connected, and communication with <i>c´</i> and -<i>a´</i> interrupted) the handle of the commutator at <span class="smcap smaller">A</span> is turned<span class="pagenum"><a id="Page_247">247</a></span> -from its mean position in <em>one</em> direction, <i>a</i> and <i>b</i> are connected, -as are <i>c</i> and <i>d</i>—as shown in the figure—while the connection -between <i>b</i> and <i>d</i> is broken. Thus the current passes from <span class="smcap smaller">P</span> -by <i>a</i> and <i>b</i>, round the needle <i>n</i>; thence to station <span class="smcap smaller">B</span>, round -needle <i>n´</i>, and by <i>b´</i> and <i>d´</i>, to the earth plate <span class="smcap">G´</span>; and so -along the earth to <span class="smcap smaller">G</span>, and by <i>d c</i>, to the negative pole <span class="smcap smaller">N</span>. -The upper end of the needle of both stations is deflected to -the right by the passage of the current in this direction. -When the handle of the commutator at <span class="smcap smaller">A</span> is turned in the -other direction, <i>b</i> and <i>c</i> are connected, as also <i>a</i> and <i>d</i>; the -current from <span class="smcap smaller">P</span> passes along <i>a d</i> to the ground plate <span class="smcap smaller">G</span>, thence -to <span class="smcap">G´</span>, along <i>d´ b´</i>, round the needle <i>n´</i>, back by the wire to -the station <span class="smcap smaller">A</span>, where, after circuiting the needle <i>n</i> in the same -direction as the needle <i>n´</i>, it travels by <i>b</i> and <i>c</i> to the negative -pole <span class="smcap smaller">N</span>. The upper end of the needle, at both stations, -is deflected to the left by the passage of the current in this -direction.</p> - -<p>It is easily seen that, with two wires and one battery, -two needles can be worked at both stations, either one -moving alone, or the other alone, or both together; but for -the two to move differently, two batteries must be used. -The systems by which either the movements of a single -needle, or of a pair of needles, may be made to indicate the -various letters of the alphabet, numerals, and so on, need -not here be described. They are of course altogether -arbitrary, except only that the more frequent occurrence of -certain letters, as <i>e</i>, <i>t</i>, <i>a</i>, renders it desirable that these -should be represented by the simplest symbols (as by a -single deflection to right or left), while letters which occur -seldom may require several deflections.</p> - -<p>One of the inventions to which the title of this paper -relates can now be understood.</p> - -<div class="figdummyl"> </div> -<div id="ip_247" class="figleft" style="max-width: 12em;"> - <img src="images/i_248.jpg" width="192" height="185" class="dummy" alt="" /> - <div class="caption"><span class="smcap">Fig. 5.</span></div></div> - -<p>In the arrangement described, when a message is transmitted, -the needle of the sender vibrates synchronously with -the needle at the station to which the message is sent. -Therefore, till that message is finished, none can be received -at the transmitting station. In what is called duplex telegraphy,<span class="pagenum"><a id="Page_248">248</a></span> -this state of things is altered, the needle at the -sending station being left unaffected by the transmitted -current, so as to be able to receive messages, and in self-recording -systems to record them. This is done by dividing -the current from the battery into two parts of equal -efficiency, acting on the needle at the transmitting station in -contrary directions, so that this needle remains unaffected, -and ready to indicate signals from -the distant station. The principle -of this arrangement is indicated in -<a href="#ip_247">Fig. 5</a>. Here <i>a b n</i> represents the -main wire of communication with -the distant station, coiled round -the needle of the transmitting -station in one direction; the dotted -lines indicate a finer short wire, -coiled round the needle in a contrary -direction. When a message -is transmitted, the current along the main wire tends to -deflect the needle at <i>n</i> in one direction, while the current -along the auxiliary wire tends to deflect it in the other -direction. If the thickness and length of the short wire are -such as to make these two tendencies equal, the needle -remains at rest, while a message is transmitted to the distant -station along the main wire. In this state of things, if a -current is sent from the distant station along the wire in the -direction indicated by the dotted arrow, this current also -circuits the auxiliary wire, but in the direction indicated by -the arrows on the dotted curve, which is the same direction -in which it circuits the main wire. Thus the needle is -deflected, and a signal received. When the direction of the -chief current at the transmitting station is reversed, so also -is the direction of the artificial current, so that again the -needle is balanced. Similarly, if the direction of the current -from the distant station is reversed, so also is the direction -in which this current traverses the auxiliary wire, so that -again both effects conspire to deflect the needle.</p> - -<p><span class="pagenum"><a id="Page_249">249</a></span> -There is, however, another way in which an auxiliary wire -may be made to work. It may be so arranged that, when a -message is transmitted, the divided current flowing equally -in opposite directions, the instrument at the sending station -is not affected; but that when the operator at the distant -station sends a current along the main wire, this neutralizes -the current coming towards him, which current had before -balanced the artificial current. The latter, being no longer -counterbalanced, deflects the needle; so that, in point of -fact, by this arrangement, the signal received at a station is -produced by the artificial current at that station, though of -course the real cause of the signal is the transmission of the -neutralizing current from the distant station.</p> - -<p>The great value of duplex telegraphy is manifest. Not -only can messages be sent simultaneously in both directions -along the wire—a circumstance which of itself would double -the work which the wire is capable of doing—but all loss -of time in arranging about the order of outward and homeward -messages is prevented. The saving of time is especially -important on long lines, and in submarine telegraphy. -It is also here that the chief difficulties of duplex telegraphy -have been encountered. The chief current and the artificial -current must exactly balance each other. For this purpose -the flow along each must be equal. In passing through -the long wire, the current has to encounter a greater resistance -than in traversing the short wire; to compensate -for this difference, the short wire must be much finer than -the long one. The longer the main wire, the more delicate -is the task of effecting an exact balance. But in the case -of submarine wires, another and a much more serious difficulty -has to be overcome. A land wire is well insulated. -A submarine wire is separated by but a relatively moderate -thickness of gutta-percha from water, an excellent conductor, -communicating directly with the earth, and is, moreover, -surrounded by a protecting sheathing of iron wires, -laid spirally round the core, within which lies the copper -conductor. Such a cable, as Faraday long since showed,<span class="pagenum"><a id="Page_250">250</a></span> -acts precisely as an enormous Leyden jar; or rather, Faraday -showed that such a cable, without the wire sheathing, -would act when submerged as a Leyden jar, the conducting -wire acting as the interior metallic coating of such a jar, -the gutta-percha as the glass of the jar (the insulating -medium), and the water acting as the exterior metallic -coating. Wheatstone showed further that such a cable, -with a wire sheathing, would act as a Leyden jar, even -though not submerged, the metal sheathing taking the part -of the exterior coating of the jar. Now, regarding the cable -thus as a condenser, we see that the transmission of a -current along it may in effect be compared with the passage -of a fluid along a pipe of considerable capacity, into which -and from which it is conveyed by pipes of small capacity. -There will be a retardation of the flow of water corresponding -to the time necessary to fill up the large part of the -pipe; the water may indeed begin to flow through as -quickly as though there were no enlargement of the bore of -the pipe, but the full flow from the further end will be -delayed. Just so it is with a current transmitted through a -submarine cable. The current travels instantly (or with the -velocity of freest electrical transmission) along the entire -line; but it does not attain a sufficient intensity to be -recognized for some time, nor its full intensity till a still -longer interval has elapsed. The more delicate the means -of recognizing its flow, the more quickly is the signal received. -The time intervals in question are not, indeed, -very great. With Thomson’s mirror galvanometer, in which -the slightest motion of the needle is indicated by a beam -of light (reflected from a small mirror moving with the -needle), the Atlantic cable conveys its signal from Valentia -to Newfoundland in about one second, while with the less -sensitive galvanometer before used the time would be rather -more than two seconds.</p> - -<p>Now, in duplex telegraphy the artificial current must be -equal to the chief current in intensity all the time; so that, -since in submarine telegraphy the current rises gradually to<span class="pagenum"><a id="Page_251">251</a></span> -its full strength and as gradually subsides, the artificial -current must do the same. Reverting to the illustration -derived from the flow of water, if we had a small pipe the -rapid flow through which was to carry as much water one -way as the slow flow through a large pipe was to carry water -the other way, then if the large pipe had a widening along -one part of its long course the short pipe would require -to have a similar widening along the corresponding part of -its short course. And to make the illustration perfect, the -widenings along the large pipe should be unequal in different -parts of the pipe’s length; for the capacity of a submarine -cable, regarded as a condenser, is different along different -parts of its length. What is wanted, then, for a satisfactory -system of duplex telegraphy in the case of submarine cables, -is an artificial circuit which shall not only correspond as -a whole to the long circuit, but shall reproduce at the -corresponding parts of its own length all the varieties of -capacity existing along various parts of the length of the -submarine cable.</p> - -<p>Several attempts have been made by electricians to -accomplish this result. Let it be noticed that two points -have to be considered: the intensity of the current’s action, -which depends on the resistance it has to overcome in -traversing the circuit; and the velocity of transmission, depending -on the capacity of various parts of the circuit to -condense or collect electricity. Varley, Stearn, and others -have endeavoured by various combinations of condensers -with resistance coils to meet these two requisites. But the -action of artificial circuits thus arranged was not sufficiently -uniform. Recently Mr. J. Muirhead, jun., has met the -difficulty in the following way (I follow partially the account -given in the <cite>Times</cite> of February 3, 1877, which the reader will -now have no difficulty in understanding):—He has formed -his second circuit by sheets of paper prepared with paraffin, -and having upon one side a strip of tinfoil, wound to and -fro to represent resistance. Through this the artificial -current is conducted. On the other side is a sheet of tinfoil<span class="pagenum"><a id="Page_252">252</a></span> -to represent the sheathing,<a id="FNanchor_29" href="#Footnote_29" class="fnanchor">29</a> and to correspond to the -capacity of the wire. Each sheet of paper thus prepared -may be made to represent precisely a given length of cable, -having enough tinfoil on one side to furnish the resistance, -and on the other to furnish the capacity. A sufficient -number of such sheets would exactly represent the cable, -and thus the artificial or non-signalling part of the current -would be precisely equivalent to the signalling part, so far -as its action on the needle at the transmitting station was -concerned. “The new plan was first tried on a working -scale,” says the <cite>Times</cite>, “on the line between Marseilles and -Bona; but it has since been brought into operation from -Marseilles to Malta, from Suez to Aden, and lastly, from -Aden to Bombay. On a recent occasion when there was -a break-down upon the Indo-European line, the duplex -system rendered essential service, and maintained telegraphic -communication which would otherwise have been most -seriously interfered with.” The invention, we may well -believe, “cannot fail to be highly profitable to the proprietors -of submarine cables,” or to bring about “before -long a material reduction in the cost of messages from -places beyond the seas.”</p> - -<div class="tb">* <span class="in2">* </span><span class="in2">* </span><span class="in2">* </span><span class="in2">*</span></div> - -<p>The next marvel of telegraphy to be described is the -transmission of actual facsimiles of writings or drawings. So -far as strict sequence of subject-matter is concerned, I ought, -perhaps, at this point, to show how duplex telegraphy has -been surpassed by a recent invention, enabling three or four -or more messages to be simultaneously transmitted telegraphically. -But it will be more convenient to consider this -wonderful advance after I have described the methods by -which facsimiles of handwriting, etc., are transmitted.</p> - -<p><span class="pagenum"><a id="Page_253">253</a></span> -Hitherto we have considered the action of the electric -current in deflecting a magnetic needle to right or left, a -method of communication leaving no trace of its transmission. -We have now to consider a method at once simpler in -principle and affording means whereby a permanent record -can be left of each message transmitted.</p> - -<div class="figdummyr"> </div> -<div id="ip_253" class="figright" style="max-width: 13.125em;"> - <img src="images/i_253.jpg" width="210" height="169" class="dummy" alt="" /> - <div class="caption"><span class="smcap">Fig. 6.</span></div></div> - -<p>If the insulated wire is twisted in the form of a helix or -coil round a bar of soft iron, the -bar becomes magnetized while -the current is passing. If the -bar be bent into the horse-shoe -form, as in <a href="#ip_253">Fig. 6</a>, where <span class="smcap">A C B</span> -represents the bar, <i>a b c d e f</i> -the coil of insulated wire, the -bar acts as a magnet while the -current is passing along the coil, -but ceases to do so as soon as -the current is interrupted.<a id="FNanchor_30" href="#Footnote_30" class="fnanchor">30</a> If, -then, we have a telegraphic wire from a distant station in -electric connection with the wire <i>a b c</i>, the part <i>e f</i> descending -to an earth-plate, then, according as the operator at that -distant station transmits or stops the current, the iron <span class="smcap">A C B</span> -is magnetized or demagnetized. The part <span class="smcap smaller">C</span> is commonly -replaced by a flat piece of iron, as is supposed to be the -case with the temporary magnets shown in <a href="#ip_254">Fig. 7</a>, where this -flat piece is below the coils.</p> - -<p>So far back as 1838 this property was applied by Morse -in America in the recording instrument which bears his -name, and is now (with slight modifications) in general use -not only in America but on the Continent. The principle<span class="pagenum"><a id="Page_254">254</a></span> -of this instrument is exceedingly simple. Its essential parts -are shown in <a href="#ip_254">Fig. 7</a>; <span class="smcap smaller">H</span> is the handle, <span class="smcap smaller">H</span> <i>b</i> the lever of the -manipulator at the station <span class="smcap smaller">A</span>. The manipulator is shown in -the position for receiving a message from the station <span class="smcap smaller">B</span> along -the wire <span class="smcap smaller">W</span>. The handle <span class="smcap">H´</span> of the manipulator at the station -<span class="smcap smaller">B</span> is shown depressed, making connection at <i>a´</i> with the wire -from the battery <span class="smcap">N´ P´</span>. Thus a current passes through the -handle to <i>c´</i>, along the wire to <i>c</i> and through <i>b</i> to the coil of -the temporary magnet <span class="smcap smaller">M</span>, after circling which it passes to the -earth at <i>e</i> and so by <span class="smcap">E´</span> to the negative pole <span class="smcap">N´</span>. The passage -of this current magnetizes <span class="smcap smaller">M</span>, which draws down the armature -<i>m</i>. Thus the lever <i>l</i>, pulled down on this side, presses upwards -the pointed style <i>s</i> against a strip of paper <i>p</i> which is -steadily rolled off from the wheel <span class="smcap smaller">W</span> so long as a message is -being received. (The mechanism for this purpose is not -indicated in <a href="#ip_254">Fig. 7</a>.) Thus, so long as the operator at <span class="smcap smaller">B</span> -holds down the handle <span class="smcap">H´</span>, the style <i>s</i> marks the moving -strip of paper, the spring <i>r</i>, under the lever <i>s l</i>, drawing the -style away so soon as the current ceases to flow and the -magnet to act. If he simply depresses the handle for an -instant, a dot is marked; if longer, a dash; and by various -combinations of dots and dashes all the letters, numerals, etc., -are indicated. When the operator at <span class="smcap smaller">B</span> has completed his -message, the handle <span class="smcap">H´</span> being raised by the spring under it -(to the position in which <span class="smcap smaller">H</span> is shown), a message can be -received at <span class="smcap smaller">B</span>.</p> - -<div id="ip_254" class="figcenter" style="max-width: 36.4375em;"> - <img src="images/i_254.jpg" width="583" height="194" alt="" /> - <div class="caption"><span class="smcap">Fig. 7.</span></div></div> - -<p><span class="pagenum"><a id="Page_255">255</a></span> -I have in the figure and description assumed that the -current from either station acts directly on the magnet -which works the recording style. Usually, in long-distance -telegraphy, the current is too weak for this, and the magnet -on which it acts is used only to complete the circuit of a -local battery, the current from which does the real work of -magnetizing <span class="smcap smaller">M</span> at <span class="smcap smaller">A</span> or <span class="smcap">M´</span> at <span class="smcap smaller">B</span>, as the case may be. A local -battery thus employed is called a <em>relay</em>.</p> - -<p>The Morse instrument will serve to illustrate the <em>principle</em> -of the methods by which facsimiles are obtained. The -details of construction are altogether different from those -of the Morse instrument; they also vary greatly in different -instruments, and are too complex to be conveniently described -here. But the principle, which is the essential point, -can be readily understood.</p> - -<p>In working the Morse instrument, the operator at <span class="smcap smaller">B</span> -depresses the handle <span class="smcap">H´</span>. Suppose that this handle is kept -depressed by a spring, and that a long strip of paper passing -uniformly between the two points at <i>a</i> prevents contact. -Then no current can pass. But if there is a hole in this -paper, then when the hole reaches <i>a</i> the two metal points -at <i>a</i> meet and the current passes. We have here the -principle of the Bain telegraph. A long strip of paper is -punched with round and long holes, corresponding to the -dots and marks of a message by the Morse alphabet. As -it passes between a metal wheel and a spring, both forming -part of the circuit, it breaks the circuit until a hole allows -the spring to touch the wheel, either for a short or longer -time-interval, during which the current passes to the other -station, where it sets a relay at work. In Bain’s system -the message is received on a chemically prepared strip of -paper, moving uniformly at the receiving station, and connected -with the negative pole of the relay battery. When -contact is made, the face of the paper is touched by a -steel pointer connected with the positive pole, and the -current which passes from the end of the pointer through<span class="pagenum"><a id="Page_256">256</a></span> -the paper to the negative pole produces a blue mark on the -chemically prepared paper.<a id="FNanchor_31" href="#Footnote_31" class="fnanchor">31</a></p> - -<p>We see that by Bain’s arrangement a paper is marked -with dots and lines, corresponding to round and elongated -holes, in a ribbon of paper. It is only a step from this to -the production of facsimiles of writings or drawings.</p> - -<p>Suppose a sheet of paper so prepared as to be a conductor -of electricity, and that a message is written on the -paper with some non-conducting substance for ink. If that -sheet were passed between the knobs at <i>a</i> (the handle <span class="smcap smaller">H</span> -being pressed down by a spring), whilst simultaneously a -sheet of Bain’s chemically prepared paper were passed -athwart the steel pointer at the receiving station, there -would be traced across the last-named paper a blue line, -which would be broken at parts corresponding to those on -the other paper where the non-conducting ink interrupted -the current. Suppose the process repeated, each paper -being slightly shifted so that the line traced across either -would be parallel and very close to the former, but precisely -corresponding as respects the position of its length. Then -this line, also, on the recording paper will be broken at -parts corresponding to those in which the line across the -transmitting paper meets the writing. If line after line be -drawn in this way till the entire breadth of the transmitting -paper has been crossed by close parallel lines, the -entire breadth of the receiving paper will be covered by -closely marked blue lines except where the writing has -broken the contact. Thus a negative facsimile of the -writing will be found in the manner indicated in Figs. 8 -and 9.<a id="FNanchor_32" href="#Footnote_32" class="fnanchor">32</a> In reality, in processes of this kind, the papers -(unlike the ribbons on Bain’s telegraph) are not carried -across in the way I have imagined, but are swept by<span class="pagenum"><a id="Page_257">257</a></span> -successive strokes of a movable pointer, along which the -current flows; but the principle is the same.</p> - -<div id="ip_257" class="figcenter" style="max-width: 37.6875em;"> - <img src="images/i_257.jpg" width="603" height="263" alt="" /> - <div class="caption floatl"><span class="smcap">Fig. 8.</span></div> - <div class="caption floatr"><span class="smcap">Fig. 9.</span></div></div> - -<p>It is essential, in such a process as I have described, -first, that the recording sheet should be carried athwart the -pointer which conveys the marking current (or the pointer -carried across the recording sheet) in precise accordance -with the motion of the transmitting sheet athwart the wire -or style which conveys the current to the long wire between -the stations (or of this style across the transmitting sheet). -The recording sheet and the transmitting sheet must also -be shifted between each stroke by an equal amount. The -latter point, is easily secured; the former is secured by -causing the mechanism which gives the transmitting style -its successive strokes to make and break circuit, by which -a temporary magnet at the receiving station is magnetized -and demagnetized; by the action of this magnet the recording -pointer is caused to start on its motion athwart the -receiving sheet, and moving uniformly it completes its -thwart stroke at the same instant as the transmitting style.</p> - -<p>Caselli’s pantelegraph admirably effects the transmission -of facsimiles. The transmitting style is carried by the -motion of a heavy pendulum in an arc of constant range -over a cylindrical surface on which the paper containing the<span class="pagenum"><a id="Page_258">258</a></span> -message, writing, or picture, is spread. As the swing of the -pendulum begins, a similar pendulum at the receiving station -begins its swing; the same break of circuit which (by demagnetizing -a temporary magnet) releases one, releases the -other also. The latter swings in an arc of precisely the -same range, and carries a precisely similar style over a -similar cylindrical surface on which is placed the prepared -receiving paper. In fact, the same pendulum at either -station is used for transmitting and for receiving facsimiles. -Nay, not only so, but each pendulum, as it swings, serves in -the work both of transmitting and recording facsimiles. As -it swings one way, it travels along a line over each of two -messages or drawings, while the other pendulum in its -synchronous swing traces a corresponding line over each of -two receiving sheets; and as it swings the other way, it -traces a line on each of two receiving sheets, corresponding -to the lines along which the transmitting style of the other -is passing along two messages or drawings. Such, at least, -is the way in which the instrument works in busy times. It -can, of course, send a message, or two messages, without -receiving any.<a id="FNanchor_33" href="#Footnote_33" class="fnanchor">33</a></p> - -<p>In Caselli’s pantelegraph matters are so arranged that -instead of a negative facsimile, like <a href="#ip_257">Fig. 9</a>, a true facsimile is -obtained in all respects except that the letters and figures -are made by closely set dark lines instead of being dark -throughout as in the message. The transmitting paper is -conducting and the ink non-conducting, as in Bakewell’s -original arrangement; but instead of the conducting paper -completing the circuit for the distant station, it completes a -short home circuit (so to speak) along which the current -travels without entering on the distant circuit When the -non-conducting ink breaks the short circuit, the current<span class="pagenum"><a id="Page_259">259</a></span> -travels in the long circuit through the recording pointer at -the receiving station; and a mark is thus made corresponding -to the inked part of the transmitting sheet instead of the -blank part, as in the older plan.</p> - -<p>The following passage from Guillemin’s “Application -of the Physical Forces” indicates the effectiveness of -Caselli’s pantelegraph not only as respects the character of -the message it conveys, but as to rapidity of transmission. -(I alter the measures from the metric to our usual system of -notation.<a id="FNanchor_34" href="#Footnote_34" class="fnanchor">34</a>) “Nothing is simpler than the writing of the -pantelegraph. The message when written is placed on the -surface of the transmitting cylinder. The clerk makes the -warning signals, and then sets the pendulum going. The -transmission of the message is accomplished automatically, -without the clerk having any work to do, and consequently -without [his] being obliged to acquire any special knowledge. -Since two despatches may be sent at the same time—and -since shorthand may be used—the rapidity of transmission -may be considerable.” “The long pendulum of Caselli’s -telegraph,” says M. Quet, “generally performs about forty -oscillations a minute, and the styles trace forty broken lines, -separated from each other by less than the hundredth part -of an inch. In one minute the lines described by the style -have ranged over a breadth of more than half an inch, and -in twenty minutes of nearly 10½ inches. As we can give the -lines a length of 4¼ inches, it follows that in twenty minutes -Caselli’s apparatus furnishes the facsimile of the writing or -drawing traced on a metallized plate 4¼ inches broad by 10½ -inches long. For clearness of reproduction, the original -writing must be very legible and in large characters.” -“Since 1865 the line from Paris to Lyons and Marseilles has -been open to the public for the transmission of messages by -this truly marvellous system.”</p> - -<p><span class="pagenum"><a id="Page_260">260</a></span> -It will easily be seen that Caselli’s method is capable of -many important uses besides the transmission of facsimiles -of handwriting. For instance, by means of it a portrait of -some person who is to be identified—whether fraudulent -absconder, or escaped prisoner or lunatic, or wife who has -eloped from her husband, or husband who has deserted his -wife, or missing child, and so on—can be sent in a few -minutes to a distant city where the missing person is likely -to be. All that is necessary is that from a photograph or -other portrait an artist employed for the purpose at the -transmitting station should, in bold and heavy lines, sketch -the lineaments of the missing person on one of the prepared -sheets, as in <a href="#ip_260">Fig. 10</a>. The portrait at the receiving station -will appear as in <a href="#ip_260">Fig. 11</a>, and if necessary an artist at this -station can darken the lines or in other ways improve the -picture without altering the likeness.</p> - -<div id="ip_260" class="figcenter" style="max-width: 32.6875em;"> - <img src="images/i_260.jpg" width="523" height="422" alt="" /> - <div class="caption floatl"><span class="smcap">Fig. 10.</span></div> - <div class="caption floatr"><span class="smcap">Fig. 11.</span></div></div> - -<p><span class="pagenum"><a id="Page_261">261</a></span> -But now we must turn to the greatest marvel of all—the -transmission of tones, tunes, and words by the electric wire.</p> - -<p>The transmission of the rhythm of an air is of course a -very simple matter. I have seen the following passage from -“Lardner’s Museum of Science and Art,” 1859, quoted as -describing an anticipation of the telephone, though in reality -it only shows what every one who has heard a telegraphic -indicator at work must have noticed, that the click of the -instrument may be made to keep time with an air. “We -were in the Hanover Street Office, when there was a pause -in the business operations. Mr. M. Porter, of the office at -Boston—the writer being at New York—asked what tune -we would have? We replied, ‘Yankee Doodle,’ and to our -surprise he immediately complied with our request. The -instrument, a Morse one, commenced drumming the notes -of the tune as perfectly and distinctly as a skilful drummer -could have made them at the head of a regiment, and many -will be astonished to hear that ‘Yankee Doodle’ can travel -by lightning.... So perfectly and distinctly were the -sounds of the tunes transmitted, that good instrumental -performers could have no difficulty in keeping time with the -instruments at this end of the wires.... That a pianist -in London should execute a fantasia at Paris, Brussels, -Berlin, and Vienna, at the same moment, and with the same -spirit, expression, and precision as if the instruments at these -distant places were under his fingers, is not only within the -limits of practicability, but really presents no other difficulty -than may arise from the expense of the performances. From -what has just been stated, it is clear that the time of music -has been already transmitted, and the production of the -sounds does not offer any more difficulty than the printing -of the letters of a despatch.” Unfortunately, Lardner -omitted to describe how this easy task was to be achieved.</p> - -<p>Reuss first in 1861 showed how a sound can be transmitted. -At the sending station, according to his method, -there is a box, into which, through a pipe in the side, the -note to be transmitted is sounded. The box is open at the<span class="pagenum"><a id="Page_262">262</a></span> -top, and across it, near the top, is stretched a membrane -which vibrates synchronously with the aerial vibrations corresponding -to the note. At the middle of the membrane, -on its upper surface, is a small disc of metal, connected by -a thin strip of copper with the positive pole of the battery at -the transmitting station. The disc also, when the machine -is about to be put in use, lightly touches a point on a metallic -arm, along which (while this contact continues) the electric -current passes to the wire communicating with the distant -station. At that station the wire is carried in a coil round -a straight rod of soft iron suspended horizontally in such a -way as to be free to vibrate between two sounding-boards. -After forming this coil, the wire which conveys the current -passes to the earth-plate and so home. As already explained, -while the current passes, the rod of iron is magnetized, but -the rod loses its magnetization when the current ceases.</p> - -<p>Now, when a note is sounded in the box at the transmitting -station, the membrane vibrates, and at each vibration -the metal disc is separated from the point which it lightly -touches when at rest. Thus contact is broken at regular -intervals, corresponding to the rate of vibration due to the -note. Suppose, for instance, the note <i>C</i> is sounded; then -there are 256 complete vibrations in a second, the electric -current is therefore interrupted and renewed, and the bar of -soft iron magnetized and demagnetized, 256 times in a second. -Now, it had been discovered by Page and Henry that when -a bar of iron is rapidly magnetized and demagnetized, it is -put into vibrations synchronizing with the interruptions of -the current, and therefore emits a note of the same tone as -that which has been sounded into the transmitting box.</p> - -<p>Professor Heisler, in his “Lehrbuch der technischen -Physik,” 1866, wrote of Reuss’s telephone: “The instrument -is still in its infancy; however, by the use of batteries of proper -strength, it already transmits not only single musical tones, -but even the most intricate melodies, sung at one end of the -line, to the other, situated at a great distance, and makes -them perceptible there with all desirable distinctness.” Dr.<span class="pagenum"><a id="Page_263">263</a></span> -Van der Weyde, of New York, states that, after reading an -account of Reuss’s telephone, he had two such instruments -constructed, and exhibited them at the meeting of the Polytechnic -Club of the American Institute. “The original -sounds were produced at the furthest extremity of the large -building (the Cooper Institute), totally out of hearing of the -Association; and the receiving instrument, standing on the -table in the lecture-room, produced, with a peculiar and -rather nasal twang, the different tunes sung into the box at -the other end of the line; not powerfully, it is true, but very -distinctly and correctly. In the succeeding summer I -improved the form of the box, so as to produce a more -powerful vibration of the membrane. I also improved the -receiving instrument by introducing several iron wires into -the coil, so as to produce a stronger vibration. I submitted -these, with some other improvements, to the meeting of the -American Association for the Advancement of Science, and -on that occasion (now seven years ago) expressed the opinion -that the instrument contained the germ of a new method of -working the electric telegraph, and would undoubtedly lead -to further improvements in this branch of science.”</p> - -<p>The telephonic successes recently achieved by Mr. Gray -were in part anticipated by La Cour, of Copenhagen, whose -method may be thus described: At the transmitting station -a tuning-fork is set in vibration. At each vibration one of -the prongs touches a fine strip of metal completing a circuit. -At the receiving station the wire conveying the electric current -is coiled round the prongs of another tuning-fork of the -same tone, but without touching them. The intermittent -current, corresponding as it does with the rate of vibration -proper to the receiving fork, sets this fork in vibration; and -in La Cour’s instrument the vibrations of the receiving fork -were used to complete the circuit of a local battery. His -object was not so much the production of tones as the use -of the vibrations corresponding to different tones, to act on -different receiving instruments. For only a fork corresponding -to the sending fork could be set in vibration by the<span class="pagenum"><a id="Page_264">264</a></span> -intermittent current resulting from the latter’s vibrations. -So that, if there were several transmitting forks, each could -send its own message at the same time, each receiving fork -responding only to the vibrations of the corresponding transmitting -fork. La Cour proposed, in fact, that his instrument -should be used in combination with other methods of telegraphic -communication. Thus, since the transmitting fork, -whenever put in vibration, sets the local battery of the -receiving station at work, it can be used to work a Morse -instrument, or it could work an ordinary Wheatstone and -Cook instrument, or it could be used for a pantelegraph. -The same wire, when different forks are used, could work -simultaneously several instruments at the receiving station. -One special use indicated by La Cour was the adaptation of -his system to the Caselli pantelegraph, whereby, instead of -one style, a comb of styles might be carried over the transmitting -and recording plates. It would be necessary, in all -such applications of his method (though, strangely enough, -La Cour’s description makes no mention of the point), that -the vibrations of the transmitting fork should admit of being -instantly stopped or “damped.”</p> - -<p>Mr. Gray’s system is more directly telephonic, as aiming -rather at the development of sound itself than at the transmission -of messages by the vibrations corresponding to -sound. A series of tuning-forks are used, which are set in -separate vibration by fingering the notes of a key-board. -The vibrations are transmitted to a receiving instrument -consisting of a series of reeds, corresponding in note to the -series of transmitting forks, each reed being enclosed in a -sounding-box. These boxes vary in length from two feet to -six inches, and are connected by two wooden bars, one of -which carries an electro-magnet, round the coils of which -pass the currents from the transmitting instrument. When -a tuning-fork is set in vibration by the performer at the -transmitting key-board, the electro-magnet is magnetized -and demagnetized synchronously with the vibrations of the -fork. Not only are vibrations thus imparted to the reed of<span class="pagenum"><a id="Page_265">265</a></span> -corresponding note, but these are synchronously strengthened -by thuds resulting from the lengthening of the iron when -magnetized.</p> - -<p>So far as its musical capabilities are concerned, Gray’s -telephone can hardly be regarded as fulfilling all the hopes -that have been expressed concerning telephonic music. -“Dreaming enthusiasts of a prophetic turn of mind foretold,” -we learn, “that a time would come when future Pattis -would sing on a London stage to audiences in New York, -Berlin, St. Petersburg, Shanghai, San Francisco, and Constantinople -all at once.” But the account of the first concert -given at a distance scarcely realizes these fond expectations. -When “Home, Sweet Home,” played at Philadelphia, came -floating through the air at the Steinway Hall, New York, -“the sound was like that of a distant organ, rather faint, for -a hard storm was in progress, and there was consequently a -great leakage of the electric current, but quite clear and -musical. The lower notes were the best, the higher being -sometimes almost inaudible. ‘The Last Rose of Summer,’ -‘Com’ è gentil,’ and other melodies, followed, with more or -less success. There was no attempt to play chords,” though -three or four notes can be sounded together. It must be -confessed that the rosy predictions of M. Strakosch (the -<i xml:lang="it" lang="it">impresario</i>) “as to the future of this instrument seem rather -exalted, and we are not likely as yet to lay on our music -from a central reservoir as we lay on gas and water, though -the experiment was certainly a very curious one.”</p> - -<p>The importance of Mr. Gray’s, as of La Cour’s inventions, -depends, however, far more on the way in which they -increase the message-bearing capacity of telegraphy than on -their power of conveying airs to a distance. At the Philadelphia -Exhibition, Sir W. Thomson heard four messages -sounded simultaneously by the Gray telephone. The Morse -alphabet was used. I have mentioned that in that alphabet -various combinations of dots and dashes are used to represent -different letters; it is only necessary to substitute the -short and long duration of a note for dots and dashes to have a<span class="pagenum"><a id="Page_266">266</a></span> -similar sound alphabet. Suppose, now, four tuning-forks at -the transmitting station, whose notes are <i>Do</i> <img class="inline" src="images/i_266.jpg" width="60" height="34" alt="Do" />, <i>Mi</i>, -<i>Sol</i>, and <i>Do</i> <img class="inline" src="images/i_266a.jpg" width="60" height="33" alt="Do" />, or say <i>C</i>, <i>E</i>, <i>G</i>, and <i>C</i>´, then by each -of these forks a separate message may be transmitted, all the -messages being carried simultaneously by the same line to -separate sounding reeds (or forks, if preferred), and received -by different clerks. With a suitable key-board, a single -clerk could send the four messages simultaneously, striking -chords instead of single notes, though considerable practice -would be necessary to transform four verbal messages at -once into the proper telephonic music, and some skill in -fingering to give the proper duration to each note.</p> - -<p>Lastly, we come to the greatest achievement of all, Professor -Graham Bell’s vocal telephone. In the autumn of -1875 I had the pleasure of hearing from Professor Bell in the -course of a ride—all too short—from Boston to Salem, Mass., -an account of his instrument as then devised, and of his -hopes as to future developments. These hopes have since -been in great part fulfilled, but I venture to predict that we -do not yet know all, or nearly all, that the vocal telephone, -in Bell’s hands, is to achieve.</p> - -<p>It ought to be mentioned at the outset that Bell claims -to have demonstrated in 1873 (a year before La Cour) the -possibility of transmitting several messages simultaneously -by means of the Morse alphabet.</p> - -<p>Bell’s original arrangement for vocal telephony was as -follows:—At one station a drumhead of goldbeaters’ skin, -about 2¾ inches in diameter, was placed in front of an -electro-magnet. To the middle of the drumhead, on the -side towards the magnet, was glued a circular piece of clockspring. -A similar electro-magnet, drumhead, etc., were -placed at the other station. When notes were sung or -words spoken before one drumhead, the vibrations of the -goldbeaters’ skin carried the small piece of clockspring<span class="pagenum"><a id="Page_267">267</a></span> -vibratingly towards and from the electro-magnet, without -producing actual contact. Now, the current which was -passing along the coil round the electro-magnet changed in -strength with each change of position of this small piece of -metal. The more rapid the vibrations, and the greater -their amplitude, the more rapid and the more intense were -the changes in the power of the electric current. Thus, the -electro-magnet at the other station underwent changes of -power which were synchronous with, and proportionate to, -those changes of power in the current which were produced -by the changes of position of the vibrating piece of clockspring. -Accordingly, the piece of clockspring at the receiving -station, and with it the drumhead there, was caused by -the electro-magnet to vibrate with the same rapidity and -energy as the piece at the transmitting station. Therefore, -as the drumhead at one station varied its vibrations in response -to the sounds uttered in its neighbourhood, so the -drumhead at the other station, varying its vibrations, emitted -similar sounds. Later, the receiving drumhead was made -unlike the transmitting one. Instead of a membrane carrying -a small piece of metal, a thin and very flexible disc of -sheet-iron, held in position by a screw, was used. This disc, -set in vibration by the varying action of an electro-magnet, -as in the older arrangement, uttered articulate sounds corresponding -to those which, setting in motion the membrane -at the transmitting station, caused the changes in the power -of the electric current and in the action of the electro-magnet.</p> - -<p>At the meeting of the British Association in 1876 -Sir W. Thomson gave the following account of the performance -of this instrument at the Philadelphia Exhibition:—“In -the Canadian department” (for Professor Bell was not at -the time an American citizen) “I heard ‘To be or not to be—there’s -the rub,’ through the electric wire; but, scorning -monosyllables, the electric articulation rose to higher flights, -and gave me passages taken at random from the New York -newspapers:—‘S. S. Cox has arrived’ (I failed to make out<span class="pagenum"><a id="Page_268">268</a></span> -the ‘S. S. Cox’), ‘the City of New York,’ ‘Senator Morton,’ -‘the Senate has resolved to print a thousand extra copies,’ -‘the Americans in London have resolved to celebrate the -coming Fourth of July.’ All this my own ears heard spoken -to me with unmistakable distinctness by the thin circular -disc armature of just such another little electro-magnet as -this which I hold in my hand. The words were shouted -with a clear and loud voice by my colleague judge, Professor -Watson, at the far end of the line, holding his mouth close -to a stretched membrane, carrying a piece of soft iron, which -was thus made to perform in the neighbourhood of an -electro-magnet, in circuit with the line, motions proportional -to the sonorific motions of the air. This, the greatest by -far of all the marvels of the electric telegraph, is due to a -young countryman of our own, Mr. Graham Bell, of Edinburgh, -and Montreal, and Boston, now about to become a -naturalized citizen of the United States. Who can but -admire the hardihood of invention which devised such very -slight means to realize the mathematical conception that, if -electricity is to convey all the delicacies of quality which -distinguish articulate speech, the strength of its current must -vary continuously, and as nearly as may be in simple proportion -to the velocity of a particle of air engaged in constituting -the sound?”</p> - -<p>Since these words were spoken by one of the highest -authorities in matters telegraphic, Professor Bell has introduced -some important modifications in his apparatus. He -now employs, not an electro-magnet, but a permanent -magnet. That is to say, instead of using at each station -such a bar of soft iron as is shown in <a href="#ip_253">Fig. 6</a>, which becomes -a magnet while the electric current is passing through the -coil surrounding it, he uses at each station a bar of iron -permanently magnetized (or preferably a powerful magnet -made of several horse-shoe bars—that is, a compound -magnet), surrounded similarly by coils of wire. No battery -is needed. Instead of a current through the coils magnetizing -the iron, the iron already magnetized causes a current<span class="pagenum"><a id="Page_269">269</a></span> -to traverse the coils whenever it acts, or rather whenever its -action changes. If an armature were placed across its ends -or poles, at the moment when it drew that armature to the -poles by virtue of its magnetic power, a current would -traverse the coils; but afterwards, so long as the armature -remained there, there would be no current. If an armature -placed near the poles were shifted rapidly in front of the -poles, currents would traverse the coils, or be induced, their -intensity depending on the strength of the magnet, the length -of the coil, and the rapidity and range of the motions. In -front of the poles of the magnet is a diaphragm of very -flexible iron (or else some other flexible material bearing a -small piece of iron on the surface nearest the poles). A -mouthpiece to converge the sound upon this diaphragm -substantially completes the apparatus at each station. Professor -Bell thus describes the operation of the instrument:—“The -motion of steel or iron in front of the poles of a -magnet creates a current of electricity in coils surrounding -the poles of the magnet, and the duration of this current of -electricity coincides with the duration of the motion of the -steel or iron moved or vibrated in the proximity of the -magnet. When the human voice causes the diaphragm to -vibrate, electrical undulations are induced in the coils around -the magnets precisely similar to the undulations of the air -produced by the voice. The coils are connected with the -line wire, and the undulations induced in them travel through -the wire, and, passing through the coils of another instrument -of similar construction at the other end of the line, are -again resolved into air undulations by the diaphragm of this -(other) instrument.”</p> - -<p>So perfectly are the sound undulations repeated—though -the instrument has not yet assumed its final form—that not -only has the lightest whisper uttered at one end of a line of -140 miles been distinctly heard at the other, but the speaker -can be distinguished by his voice when he is known to the -listener. So far as can be seen, there is every room to -believe that before long Professor Bell’s grand invention will<span class="pagenum"><a id="Page_270">270</a></span> -be perfected to such a degree that words uttered on the -American side of the Atlantic will be heard distinctly after -traversing 2000 miles under the Atlantic, at the European -end of the submarine cable—so that Sir W. Thomson -at Valentia could tell by the voice whether Graham Bell, -or Cyrus Field, or his late colleague Professor Watson, -were speaking to him from Newfoundland. Yet a single -wave of those which toss in millions on the Atlantic, rolling -in on the Irish strand, would utterly drown the voices -thus made audible after passing beneath two thousand -miles of ocean.</p> - -<p>Here surely is the greatest of telegraphic achievements. -Of all the marvels of telegraphy—and they are many—none -are equal to, none seem even comparable with, this one. -Strange truly is the history of the progress of research -which has culminated in this noble triumph, wonderful the -thought that from the study of the convulsive twitchings of -a dead frog by Galvani, and of the quivering of delicately -poised magnetic needles by Ampère, should gradually have -arisen through successive developments a system of communication -so perfect and so wonderful as telegraphy has -already become, and promising yet greater marvels in the -future.</p> - -<p>The last paragraph had barely been written when news -arrived of another form of telephone, surpassing Gray’s and -La Cour’s in some respects as a conveyor of musical tones, -but as yet unable to speak like Bell’s. It is the invention -of Mr. Edison, an American electrician. He calls it the -motograph. He discovered about six years ago the curious -property on which the construction of the instrument -depends. If a piece of paper moistened with certain -chemical solutions is laid upon a metallic plate connected -with the positive pole of a galvanic battery, and a platinum -wire connected with the negative pole is dragged over the -moistened paper, the wire slides over the paper like smooth -iron over ice—the usual friction disappearing so long as -the current is passing from the wire to the plate through<span class="pagenum"><a id="Page_271">271</a></span> -the paper. At the receiving station of Mr. Edison’s motograph -there is a resonating box, from one face of which -extends a spring bearing a platinum point, which is pressed -by the spring upon a tape of chemically prepared paper. -This tape is steadily unwound, drawing by its friction the -platinum point, and with it the face of the resonator, outwards. -This slight strain on the face of the resonator -continues so long as no current passes from the platinum -point to the metallic drum over which the moistened tape -is rolling. But so soon as a current passes, the friction -immediately ceases, and the face of the resonator resumes -its normal position. If then at the transmitting station -there is a membrane or a very fine diaphragm (as in -Reuss’s or Bell’s arrangement) which is set vibrating by -a note of any given tone, the current, as in those arrangements, -is transmitted and stopped at intervals corresponding -to the tone, and the face of the resonating box is freed -and pulled at the same intervals. Hence, it speaks the -corresponding tone. The instrument appears to have the -advantage over Gray’s in range. In telegraphic communication -Gray’s telephone is limited to about one octave. -Edison’s extends from the deepest bass notes to the highest -notes of the human voice, which, when magnets are employed, -are almost inaudible. But Edison’s motograph has -yet to learn to speak.</p> - -<p>Other telegraphic marvels might well find a place here. -I might speak of the wonders of submarine telegraphy, -and of the marvellous delicacy of the arrangements by -which messages by the Atlantic Cable are read, and not -only read, but made to record themselves. I might dwell, -again, on the ingenious printing telegraph of Mr. Hughes, -which sets up its own types, inks them, and prints them, or -on the still more elaborate plan of the Chevalier Bonelli -“for converting the telegraph stations into so many type-setting -workshops.” But space would altogether fail me -to deal properly with these and kindred marvels. There -is, however, one application of telegraphy, especially interesting<span class="pagenum"><a id="Page_272">272</a></span> -to the astronomer, about which I must say a few words: -I mean, the employment of electricity as a regulator of time. -Here again it is the principle of the system, rather than -details of construction, which I propose to describe. Suppose -we have a clock not only of excellent construction, -but under astronomical surveillance, so that when it is a -second or so in error it is set right again by the stars. Let -the pendulum of this clock beat seconds; and at each beat -let a galvanic current be made and broken. This may be -done in many ways—thus the pendulum may at each swing -tilt up a very light metallic hammer, which forms part of -the circuit when down; or the end of the pendulum may -be covered with some non-conducting substance which -comes at each swing between two metallic springs in very -light contact, separating them and so breaking circuit; or -in many other ways the circuit may be broken. When the -circuit is made, let the current travel along a wire which -passes through a number of stations near or remote, traversing -at each the coils of a temporary magnet. Then, at -each swing of the pendulum of the regulating clock, each -magnet is magnetized and demagnetized. Thus each, once -in a second, draws to itself, and then releases its armature, -which is thereupon pulled back by a spring. Let the armature, -when drawn to the magnet, move a lever by which -one tooth of a wheel is carried forward. Then the wheel -is turned at the rate of one tooth per second. This wheel -communicates motion to others in the usual way. In fact, -we have at each station a clock driven, <em>not</em> by a weight -or spring and with a pendulum which allows one tooth of -an escapement wheel to pass at each swing, but by the -distant regulating clock which turns a driving wheel at the -rate of one tooth per second, that is, one tooth for each -swing of the regulating clock’s pendulum. Each clock, -then, keeps perfect time with the regulating clock. In -astronomy, where it is often of the utmost importance to -secure perfect synchronism of observation, or the power of -noting the exact difference of time between observations<span class="pagenum"><a id="Page_273">273</a></span> -made at distant stations, not only can the same clock thus -keep time for two observers hundreds of miles apart, but -each observer can record by the same arrangement the -moment of the occurrence of some phenomenon. For if -a tape be unwound automatically, as in the Morse instrument, -it is easy so to arrange matters that every second’s -beat of the pendulum records itself by a dot or short line -on the tape, and that the observer can with a touch make -(or break) contact at the instant of observation, and so a -mark be made properly placed between two seconds’ marks—thus -giving the precise time when the observation was -made. Such applications, however, though exceedingly -interesting to astronomers, are not among those in which -the general public take chief interest. There was one -occasion, however, when astronomical time-relations were -connected in the most interesting manner with one of the -greatest of all the marvels of telegraphy: I mean, when -the <i>Great Eastern</i> in mid-ocean was supplied regularly -with Greenwich time, and this so perfectly (and therefore -with such perfect indication of her place in the Atlantic), -that when it was calculated from the time-signals that the -buoy left in open ocean to mark the place of the cut cable -had been reached, and the captain was coming on deck -with several officers to look for it, the buoy announced its -presence by thumping the side of the great ship.</p> - -<hr /> - -<p><span class="pagenum"><a id="Page_274">274</a></span></p> - -<div class="chapter"> -<h2><a id="THE_PHONOGRAPH_OR_VOICE-RECORDER"></a><i>THE PHONOGRAPH, OR VOICE-RECORDER.</i></h2> -</div> - -<p class="in0">In the preceding essay I have described the wonderful instrument -called the telephone, which has recently become -as widely known in this country as in America, the country -of its first development. I propose now briefly to describe -another instrument—the phonograph—which, though not a -telegraphic instrument, is related in some degree to the -telephone. In passing, I may remark that some, who as -telegraphic specialists might be expected to know better, -have described the phonograph as a telegraphic invention. -A writer in the <cite>Telegraphic Journal</cite>, for instance, who had -mistaken for mine a paper on the phonograph in one of -our daily newspapers, denounced me (as the supposed -author of that paper) for speaking of the possibility of -crystallizing sound by means of this instrument; and then -went on to speak of the mistake I (that is, said author) had -made in leaving my own proper subject of study to speak of -telegraphic instruments and to expatiate on the powers of -electricity. In reality the phonograph has no relation to -telegraphy whatever, and its powers do not in the slightest -degree depend on electricity. If the case had been otherwise, -it may be questioned whether the student of astronomy, -or of any other department of science, should be considered -incompetent of necessity to describe a telegraphic instrument, -or to discuss the principles of telegraphic or electrical science. -What should unquestionably be left to the specialist, is the<span class="pagenum"><a id="Page_275">275</a></span> -description of the practical effect of details of instrumental -construction, and the like—for only he who is in the habit -of using special instruments or classes of instrument can be -expected to be competent adequately to discuss such matters.</p> - -<p>Although, however, the phonograph is not an instrument -depending, like the telephone, on the action of electricity -(in some form or other), yet it is related closely enough to -the telephone to make the mistake of the <cite>Telegraphic</cite> -journalist a natural one. At least, the mistake would be -natural enough for any one but a telegraphic specialist; the -more so that Mr. Edison is a telegraphist, and that he has -effected several important and interesting inventions in telegraphic -and electrical science. For instance, in the previous -article, pp. 270, 271, I had occasion to describe at -some length the principles of his “Motograph.” I spoke -of it as “another form of telephone, surpassing Gray’s -and La Cour’s in some respects as a conveyer of musical -tones, but as yet unable to speak like Bell’s ... in -telegraphic communication.” I proceeded: “Gray’s telephone -is limited to about one octave. Edison’s extends -from the deepest bass notes to the highest notes of the -human voice, which, when magnets are employed, are almost -inaudible; but it has yet to learn to speak.”</p> - -<p>The phonograph is an instrument which <em>has</em> learned to -speak, though it does not speak at a distance like the telephone -or the motograph. Yet there seems no special reason -why it should not combine both qualities—the power of -repeating messages at considerable intervals of time after -they were originally spoken, and the power of transmitting -them to great distances.</p> - -<p>I have said that the phonograph is an instrument closely -related to the telephone. If we consider this feature of the -instrument attentively, we shall be led to the clearer recognition -of the acoustical principles on which its properties -depend, and also of the nature of some of the interesting -acoustical problems on which light seems likely to be thrown -by means of experiments with this instrument.</p> - -<p><span class="pagenum"><a id="Page_276">276</a></span> -In the telephone a stretched membrane, or a diaphragm -of very flexible iron, vibrates when words are uttered in its -neighbourhood. When a stretched membrane is used, with -a small piece of iron at the centre, this small piece of iron, -as swayed by the vibrations of the membrane, causes electrical -undulations to be induced in the coils round the poles -of a magnet placed in front of the membrane. These undulations -travel along the wire and pass through the coils of -another instrument of similar construction at the other end -of the wire, where, accordingly, a stretched membrane -vibrates precisely as the first had done. The vibrations of -this membrane excite atmospheric vibrations identical in -character with those which fell upon the first membrane -when the words were uttered in its neighbourhood; and -therefore the same words appear to be uttered in the neighbourhood -of the second membrane, however far it may be -from the transmitting membrane, so only that the electrical -undulations are effectually transmitted from the sending to -the receiving instrument.</p> - -<p>I have here described what happened in the case of that -earlier form of the telephone in which a stretched membrane -of some such substance as goldbeater’s skin was employed, -at the centre of which only was placed a small piece of iron. -For in its bearing on the subject of the phonograph, this -particular form of telephonic diaphragm is more suggestive -than the later form in which very flexible iron was employed. -We see that the vibrations of a small piece of iron at the -centre of a membrane are competent to reproduce all the -peculiarities of the atmospheric waves which fall upon the -membrane when words are uttered in its neighbourhood. -This must be regarded, I conceive, as a remarkable acoustical -discovery. Most students of acoustics would have -surmised that to reproduce the motions merely of the central -parts of a stretched diaphragm would be altogether insufficient -for the reproduction of the complicated series of -sound-waves corresponding to the utterance of words. I -apprehend that if the problem had originally been suggested<span class="pagenum"><a id="Page_277">277</a></span> -simply as an acoustical one, the idea entertained would have -been this—that though the motions of a diaphragm receiving -vocal sound-waves <em>might</em> be generated artificially in such -sort as to produce the same vocal sounds, yet this could only -be done by first determining what particular points of the -diaphragm were centres of motion, so to speak, and then -adopting some mechanical arrangements for giving to small -portions of the membrane at these points the necessary -oscillating motions. It would not, I think, have been -supposed that motions communicated to the centre of the -diaphragm would suffice to make the whole diaphragm -vibrate properly in all its different parts.</p> - -<p>Let us briefly consider what was before known about the -vibrations of plates, discs, and diaphragms, when particular -tones were sounded in their neighbourhood; and also what -was known respecting the requirements for vocal sounds -and speech as distinguished from simple tones. I need -hardly say that I propose only to consider these points in a -general, not in a special, manner.</p> - -<p>We must first carefully draw a distinction between the -vibrations of a plate or disc which is itself the source of -sound, and those vibrations which are excited in a plate or -disc by sound-waves otherwise originated. If a disc or -plate of given size be set in vibration by a blow or other -impulse it will give forth a special sound, according to the -place where it is struck, or it will give forth combinations of -the several tones which it is capable of emitting. On the -other hand, experiment shows that a diaphragm like that -used in the telephone—not only the electric telephone, but -such common telephones as have been sold of late in large -quantities in toy shops, etc.—will respond to any sounds -which are properly directed towards it, not merely reproducing -sounds of different tones, but all the peculiarities -which characterize vocal sounds. In the former case, the -size of a disc and the conditions under which it is struck -determine the nature of its vibrations, and the air responds -to the vibrations thus excited; in the latter, the air is set<span class="pagenum"><a id="Page_278">278</a></span> -moving in vibrations of a special kind by the sounds or -words uttered, and the disc or diaphragm responds to these -vibrations. Nevertheless, though it is important that this distinction -be recognized, we can still learn, from the behaviour -of discs and plates set in vibration by a blow or other impulse, -the laws according to which the actual motions of the -various parts of a vibrating disc or plate take place. We -owe to Chladni the invention of a method for rendering -visible the nature of such motions.</p> - -<p>Certain electrical experiments of Lichtenberg suggested -to Chladni the idea of scattering fine sand over the plate or -disc whose motions he wished to examine. If a horizontal -plate covered with fine sand is set in vibration, those parts -which move upwards and downwards scatter the sand from -their neighbourhood, while on those points which undergo -no change of position the sand will remain. Such points are -called <em>nodes</em>; and rows of such points are called <em>nodal lines</em>, -which may be either straight or curved, according to circumstances.</p> - -<p>If a square plate of glass is held by a suitable clamp at -its centre, and the middle point of a side is touched while -a bow is drawn across the edge near a corner, the sand is -seen to gather in the form of a cross dividing the square into -four equal squares—like a cross of St George. If the -finger touches a corner, and the bow is drawn across the -middle of a side, the sand forms a cross dividing the square -along its diagonals—like a cross of St Andrew. Touching -two points equidistant from two corners, and drawing the -bow along the middle of the opposite edge, we get the -diagonal cross and also certain curved lines of sand -systematically placed in each of the four quarters into which -the diagonals divide the square. We also have, in this case, -a far shriller note from the vibrating plate. And so, by -various changes in the position of the points clamped by the -finger and of the part of the edge along which the bow is -drawn, we can obtain innumerable varieties of nodal lines -and curves along which the sand gathers upon the surface of -the vibrating plate.</p> - -<p><span class="pagenum"><a id="Page_279">279</a></span> -When we take a circular plate of glass, clamped at the -middle, and touching one part of its edge with the finger, -draw the bow across a point of the edge half a quadrant from -the finger, we see the sand arrange itself along two diameters -intersecting at right angles. If the bow is drawn at a point -one-third a quadrant from the finger-clamped point, we get -a six-pointed star. If the bow is drawn at a point a fourth -of a quadrant from the finger-clamped point, we get an eight-pointed -star. And so we can get the sand to arrange itself -into a star of any even number of points; that is, we can get -a star of four, six, eight, ten, twelve, etc., points, but not of -three, five, seven, etc.</p> - -<p>In these cases the centre of the plate or disc has been -fixed. If, instead, the plate or disc be fixed by a clip at the -edge, or clamped elsewhere than at the centre, we find the -sand arranging itself into other forms, in which the centre -may or may not appear; that is, the centre may or may not -be nodal, according to circumstances.</p> - -<p>A curious effect is produced if very fine powder be strewn -along with the sand over the plate. For it is found that the -dust gathers, not where the nodes or places of no vibration -lie, but where the motion is greatest. Faraday assigns as the -cause of this peculiarity the circumstance that “the light -powder is entangled by the little whirlwinds of air produced -by the vibrations of the plate; it cannot escape from the -little cyclones, though the heavier sand particles are readily -driven through them; when, therefore, the motion ceases, -the light powder settles down in heaps at the places where -the vibration was a maximum.” In proof of this theory we -have the fact that “in vacuo no such effect is produced; all -powders light and heavy move to the nodal lines.” (Tyndall -on “Sound.”)</p> - -<p>Now if we consider the meaning of such results as these, -we shall begin to recognize the perplexing but also instructive -character of the evidence derived from the telephone, and -applied to the construction of the phonograph. It appears -that when a disc is vibrating under such special conditions<span class="pagenum"><a id="Page_280">280</a></span> -as to give forth a particular series of tones (the so-called -fundamental tone of the disc and other tones combined -with it which belong to its series of overtones), the various -parts of the disc are vibrating to and fro in a direction square -to the face of the disc, except certain points at which there -is no vibration, these points together forming curves of -special forms along the substance of the disc.</p> - -<p>When, on the other hand, tones of various kinds are -sounded in the neighbourhood of a disc or of a stretched -circular membrane, we may assume that the different parts of -the disc are set in vibration after a manner at least equally -complicated. If the tones belong to the series which could -be emitted by the diaphragm when struck, we can understand -that the vibrations of the diaphragm would resemble those -which would result from a blow struck under special conditions. -When other tones are sounded, it may be assumed -that the sound-waves which reach the diaphragm cause it to -vibrate as though not the circumference (only) but a circle -in the substance of the diaphragm—concentric, of course, -with the circumference, and corresponding in dimensions -with the tone of the sounds—were fixed. If a drum of given -size is struck, we hear a note of particular tone. If we heard, -as the result of a blow on the same drum, a much higher -tone, we should know that in some way or other the effective -dimensions of the drum-skin had been reduced—as for -instance, by a ring firmly pressed against the inside of the -skin. So when a diaphragm is responding to tones other -than those corresponding to its size, tension, etc., we infer -that the sound-waves reaching it cause it to behave, so far as -its effective vibrating portion is concerned, as though its -conformation had altered. When several tones are responded -to by such a diaphragm, we may infer that the vibrations of -the diaphragm are remarkably complicated.</p> - -<p>Now the varieties of vibratory motion to which the -diaphragm of the telephone has been made to respond have -been multitudinous. Not only have all orders of sound singly -and together been responded to, but vocal sounds which in<span class="pagenum"><a id="Page_281">281</a></span> -many respects differ widely from ordinary tones are repeated, -and the peculiarities of intonation which distinguish one -voice from another have been faithfully reproduced.</p> - -<p>Let us consider in what respects vocal sounds, and -especially the sounds employed in speech, differ from mere -combinations of ordinary tones.</p> - -<p>It has been said, and with some justice, that the organ -of voice is of the nature of a reed instrument. A reed -instrument, as most persons know, is one in which musical -sounds are produced by the action of a vibrating reed in -breaking up a current of air into a series of short puffs. -The harmonium, accordion, concertina, etc., are reed instruments, -the reed for each note being a fine strip of metal -vibrating in a slit. The vocal organ of man is at the top of -the windpipe, along which a continuous current of air can be -forced by the lungs. Certain elastic bands are attached to the -head of the windpipe, almost closing the aperture. These vocal -chords are thrown into vibration by the current of air from -the lungs; and as the rate of their vibration is made to vary -by varying their tension, the sound changes in tone. So far, -we have what corresponds to a reed instrument admitting of -being altered in pitch so as to emit different notes. The -mouth, however, affects the character of the sound uttered -from the throat. The character of a <em>tone</em> emitted by the -throat cannot be altered by any change in the configuration -of the mouth; so that if a single tone were in reality produced -by the vocal chords, the resonance of the mouth -would only strengthen that tone more or less according to -the figure given to the cavity of the mouth at the will of the -singer or speaker. But in reality, besides the fundamental -tone uttered by the vocal chords, a series of overtones are -produced. Overtones are tones corresponding to vibration -at twice, three times, four times, etc., the rate of the vibration -producing the fundamental tone. Now the cavity of the -mouth can be so modified in shape as to strengthen either -the fundamental tone or any one of these overtones. And -according as special tones are strengthened in this way<span class="pagenum"><a id="Page_282">282</a></span> -various vocal sounds are produced, without changing the -pitch or intensity of the sound actually uttered. Calling the -fundamental tone the first tone, the overtones just mentioned -the second, third, fourth, etc., tones respectively (after Tyndall), -we find that the following relations exist between the -combinations of these tones and the various vowel sounds:—</p> - -<p>If the lips are pushed forward so as to make the cavity -of the mouth deep and the orifice of the mouth small, we -get the deepest resonance of which the mouth is capable, -the fundamental tone is reinforced, while the higher tones -are as far as possible thrown into the shade. The resulting -vowel sound is that of deep U (“oo” in “hoop”).</p> - -<p>If the mouth is so far opened that the fundamental tone -is accompanied by a strong second tone (the next higher -octave to the fundamental tone), we get the vowel sound O -(as in “hole”). The third and fourth tones feebly accompanying -the first and second make the sound more perfect, -but are not necessary.</p> - -<p>If the orifice of the mouth is so widened, and the volume -of the cavity so reduced, that the fundamental tone is lost, -the second somewhat weakened, and the third given as the -chief tone, with very weak fourth and fifth tones, we have -the vowel sound A.</p> - -<p>To produce the vowel sound E, the resonant cavity of -the mouth must be considerably reduced. The fourth tone -is the characteristic of this vowel. Yet the second tone also -must be given with moderate strength. The first and third -tones must be weak, and the fifth tone should be added with -moderate strength.</p> - -<p>To produce the vowel sound A, as in “far,” the higher -overtones are chiefly used, the second is wanting altogether, -the third feeble, the higher tones—especially the fifth and -seventh—strong.</p> - -<p>The vowel sound I, as in “fine,” it should be added, is -not a simple sound, but diphthongal. The two sounds whose -succession gives the sound we represent (erroneously) by a -single letter I (long), are not very different from “a” as in<span class="pagenum"><a id="Page_283">283</a></span> -“far,” and “ee” (or “i” as in “ravine”); they, lie, however, -in reality, respectively between “a” in “far” and -“fat,” and “i” in “ravine” and “pin.” Thus the tones and -overtones necessary for sounding “I” long, do not require -a separate description, any more than those necessary for -sounding other diphthongs, as “oi,” “oe,” and so forth.</p> - -<p>We see, then, that the sound-waves necessary to reproduce -accurately the various vowel sounds, are more -complicated than those which would correspond to the -fundamental tones simply in which any sound may be uttered. -There must not only be in each case certain overtones, but -each overtone must be sounded with its due degree of -strength.</p> - -<p>But this is not all, even as regards the vowel sounds, the -most readily reproducible peculiarities of ordinary speech. -Spoken sounds differ from musical sounds properly so called, -in varying in pitch throughout their continuance. So far as -tone is concerned, apart from vowel quality, the speech note -may be imitated by sliding a finger up the finger-board -of a violin while the bow is being drawn. A familiar -illustration of the varying pitch of a speech note is found -in the utterance of Hamlet’s question, “Pale, or red?” with -intense anxiety of inquiry, if one may so speak. “The -speech note on the word ‘pale’ will consist of an upward -movement of the voice, while that on ‘red’ will be a downward -movement, and in both words the voice will traverse -an interval of pitch so wide as to be conspicuous to ordinary -ears; while the cultivated perception of the musician will -detect the voice moving through a less interval of pitch -while he is uttering the word ‘or’ of the same sentence. -And he who can record in musical notation the sounds -which he hears, will perceive the musical interval traversed -in these vocal movements, and the place also of these -speech notes on the musical staff.” Variations of this kind, -only not so great in amount, occur in ordinary speech; and -no telephonic or phonographic instrument could be regarded -as perfect, or even satisfactory, which did not reproduce them.</p> - -<p><span class="pagenum"><a id="Page_284">284</a></span> -But the vowel sounds are, after all, combinations and -modifications of musical tones. It is otherwise with consonantal -sounds, which, in reality, result from various ways -in which vowel sounds are commenced, interrupted (wholly -or partially), and resumed. In one respect this statement -requires, perhaps, some modification—a point which has not -been much noticed by writers on vocal sounds. In the case -of liquids, vowel sounds are not partially interrupted only, as -is commonly stated. They cease entirely as vowel sounds, -though the utterance of a vocal sound is continued when a -liquid consonant is uttered. Let the reader utter any word -in which a liquid occurs, and he will find that while the -liquid itself is sounded the vowel sounds preceding or -following the liquid cease entirely. Repeating slowly, for -example, the word “remain,” dwelling on all the liquids, we -find that while the “r” is being sounded the “ē” sound -cannot be given, and this sound ceases so soon as the “m” -is sounded; similarly the long “a” sound can only be -uttered when the “m” sound ceases, and cannot be carried -on into the sound of the final liquid “n.” The liquids are, -in fact, improperly called semi-vowels, since no vowel sound -can accompany their utterance. The tone, however, with -which they are sounded can be modified during their -utterance. In sounding labials the emission of air is not -stopped completely at any moment. The same is true of -the sibilants s, z, sh, zh, and of the consonants g, j, f, v, th -(hard and soft). These are called, on this account, <em>continuous</em> -consonants. The only consonants in pronouncing which -the emission of air is for a moment entirely stopped, are the -true mutes, sometimes called the six <em>explosive</em> consonants, -b, p, t, d, k, and g.</p> - -<p>To reproduce artificially sounds resembling those of the -consonants in speech, we must for a moment interrupt, -wholly for explosive and partially for continuous consonant -sounds, the passage of air through a reed pipe. Tyndall -thus describes an experiment of this kind in which an -imperfect imitation of the sound of the letter “m” was<span class="pagenum"><a id="Page_285">285</a></span> -obtained—an imitation only requiring, to render it perfect, -as I have myself experimentally verified, attention to the -consideration respecting liquids pointed out in the preceding -paragraph. “Here,” says Tyndall, describing the experiment -as conducted during a lecture, “is a free reed fixed in a -frame, but without any pipe associated with it, mounted on -the acoustic bellows. When air is urged through the orifice, -it speaks in this forcible manner. I now fix upon the frame -of the reed a pyramidal pipe; you notice a change in the -clang, and, by pushing my flat hand over the open end of -the pipe, the similarity between the sounds produced and -those of the human voice is unmistakable. Holding the -palm of my hand over the end of the pipe, so as to close it -altogether, and then raising my hand twice in quick succession, -the word ‘mamma’ is heard as plainly as if it were -uttered by an infant. For this pyramidal tube I now -substitute a shorter one, and with it make the same -experiment. The ‘mamma’ now heard is exactly such as -would be uttered by a child with a stopped nose. Thus, by -associating with a vibrating reed a suitable pipe, we can -impart to the sound of the reed the qualities of the human -voice.” The “m” obtained in these experiments was, however, -imperfect. To produce an “m” sound such as an -adult would utter without a “stopped nose,” all that is -necessary is to make a small opening (experiment readily -determines the proper size and position) in the side of the -pyramidal pipe, so that, as in the natural utterance of this -liquid, the emission of air is not altogether interrupted.</p> - -<p>I witnessed in 1874 some curious illustrations of the -artificial production of vocal sounds, at the Stevens Institute, -Hoboken, N.J., where the ingenious Professor Mayer (who -will have, I trust, a good deal to say about the scientific -significance of telephonic and phonographic experiments -before long) has acoustic apparatus, including several -talking-pipes. By suitably moving his hand on the top of -some of these pipes, he could make them speak certain words -with tolerable distinctness, and even utter short sentences.<span class="pagenum"><a id="Page_286">286</a></span> -I remember the performance closed with the remarkably -distinct utterance, by one profane pipe, of the words -euphemistically rendered by Mark Twain (in his story of the -Seven Sleepers, I think), “Go thou to Hades!”</p> - -<p>Now, the speaking diaphragm in the telephone, as in -the phonograph, presently to be described, must reproduce -not only all the varieties of sound-wave corresponding to -vowel sounds, with their intermixtures of the fundamental -tone and its overtones and their inflexions or sliding -changes of pitch, but also all the effects produced on the -receiving diaphragm by those interruptions, complete or -partial, of aerial emission which correspond to the pronunciation -of the various consonant sounds. It might certainly -have seemed hopeless, from all that had been before known -or surmised respecting the effects of aerial vibrations on -flexible diaphragms, to attempt to make a diaphragm speak -artificially—in other words, to make the movements of all -parts of it correspond with those of a diaphragm set in -vibration by spoken words—by movements affecting only -its central part. It is in the recognition of the possibility -of this, or rather in the discovery of the fact that the movements -of a minute portion of the middle of a diaphragm -regulate the vibratory and other movements of the entire -diaphragm, that the great scientific interest of Professor -Graham Bell’s researches appears to me to reside.</p> - -<p>It may be well, in illustration of the difficulties with -which formerly the subject appeared to be surrounded, to -describe the results of experiments which preceded, though -they can scarcely be said to have led up to, the invention -of artificial ways of reproducing speech. I do not now -refer to experiments like those of Kratzenstein of St. -Petersburg, and Von Kempelen of Vienna, in 1779, and -the more successful experiments by Willis in later years, -but to attempts which have been made to obtain material -records of the aerial motions accompanying the utterance -of spoken words. The most successful of these attempts -was that made by Mr. W. H. Barlow. His purpose was<span class="pagenum"><a id="Page_287">287</a></span> -“to construct an instrument which should record the pneumatic -actions” accompanying the utterance of articulated -sounds “by diagrams, in a manner analogous to that in -which the indicator-diagram of a steam-engine records the -action of the engine.” He perceived that the actual aerial -pressures involved being very small and very variable, and -the succession of impulses and changes of pressure being -very rapid, it was necessary that the moving parts should -be very light, and that the movement and marking should -be accomplished with as little friction as possible. The -instrument he constructed consisted of a small speaking-trumpet -about four inches long, having an ordinary mouthpiece -connected to a tube half an inch in diameter, the -thin end of which widened out so as to form an aperture -of 2¼ inches diameter. This aperture was covered with -a membrane of goldbeater’s skin, or thin gutta-percha. A -spring carrying a marker was made to press against the -membrane with a slight initial pressure, to prevent as far as -possible the effects of jarring and consequent vibratory -action. A light arm of aluminium was connected with the -spring, and held the marker; and a continuous strip of -paper was made to pass under the marker in the manner -employed in telegraphy. The marker consisted of a small, -fine sable brush, placed in a light tube of glass one-tenth of -an inch in diameter, the tube being rounded at the lower -end, and pierced with a hole about one-twentieth of an inch -in diameter. Through this hole the tip of the brush projected, -and was fed by colour put into the glass tube by -which it was held. It should be added that, to provide -for the escape of air passing through the speaking-trumpet, -a small opening was made in the side, so that the pressure -exerted upon the membrane was that due to the excess -of air forced into the trumpet over that expelled through -the orifice. The strength of the spring which carried the -marker was so adjusted to the size of the orifice that, while -the lightest pressures arising under articulation could be -recorded, the greatest pressures should not produce a movement -exceeding the width of the paper.</p> - -<p><span class="pagenum"><a id="Page_288">288</a></span> -“It will be seen,” says Mr. Barlow, “that in this construction -of the instrument the sudden application of -pressure is as suddenly recorded, subject only to the modifications -occasioned by the inertia, momentum, and friction -of the parts moved. But the record of the sudden cessation -of pressure is further affected by the time required to discharge -the air through the escape-orifice. Inasmuch, however, -as these several effects are similar under similar -circumstances, the same diagram should always be obtained -from the same pneumatic action when the instrument is -in proper adjustment; and this result is fairly borne out by -the experiments.”</p> - -<p>The defect of the instrument consisted in the fact that -it recorded changes of pressure only; and in point of -fact it seems to result, from the experiments made with it, -that it could only indicate the order in which explosive, -continuant, and liquid consonants succeeded each other in -spoken words, the vowels being all expressed in the same -way, and only one letter—the rough R, or R with a burr—being -always unmistakably indicated. The explosives were -represented by a sudden sharp rise and fall in the recorded -curve; the height of the rise depending on the strength -with which the explosive is uttered, not on the nature of the -consonant itself. Thus the word “tick” is represented -by a higher elevation for the “t” than for the “k,” but the -word “kite” by a higher elevation for the “k” than for -the “t.” It is noteworthy that there is always a second -smaller rise and fall after the first chief one, in the case -of each of the explosives. This shows that the membrane, -having first been forcibly distended by the small aerial explosion -accompanying the utterance of such a consonant, -sways back beyond the position where the pressure and -the elasticity of the membrane would (for the moment) -exactly balance, and then oscillates back again over that -position before returning to its undistended condition. -Sometimes a third small elevation can be recognized, and -when an explosive is followed by a rolling “r” several<span class="pagenum"><a id="Page_289">289</a></span> -small elevations are seen. The continuous consonants produce -elevations less steep and less high; aspirates and -sibilants give rounded hills. But the results vary greatly -according to the position of a consonant; and, so far as I -can make out from a careful study of the very interesting -diagrams accompanying Mr. Barlow’s paper, it would be -quite impossible to define precisely the characteristic records -even of each order of consonantal sounds, far less of each -separate sound.</p> - -<p>We could readily understand that the movement of the -central part of the diaphragm in the telephone should give -much more characteristic differences for the various sounds -than Barlow’s logograph. For if we imagine a small pointer -attached to the centre of the face of the receiving diaphragm -while words are uttered in its neighbourhood, the end of -that pointer would not only move to and fro in a direction -square to the face of the diaphragm, as was the case with -Barlow’s marker, but it would also sway round its mean -position in various small circles or ovals, varying in size, -shape, and position, according to the various sounds uttered. -We might expect, then, that if in any way a record of the -actual motions of the extremity of that small pointer could -be obtained, in such sort that its displacement in directions -square to the face of the diaphragm, as well as its swayings -around its mean position, would be indicated in some -pictorial manner, the study of such records would indicate -the exact words spoken near the diaphragm, and even, -perhaps, the precise tones in which they were uttered. For -Barlow’s logograph, dealing with one only of the orders -of motion (really triple in character), gives diagrams in -which the general character of the sounds uttered is clearly -indicated, and the supposed records would show much -more.</p> - -<p>But although this might, from <i xml:lang="la" lang="la">à priori</i> considerations, -have been reasonably looked for, it by no means follows -that the actual results of Bell’s telephonic experiments could -have been anticipated. That the movement of the central<span class="pagenum"><a id="Page_290">290</a></span> -part of the diaphragm should suffice to show that such and -such words had been uttered, is one thing; but that these -movements should of themselves suffice, if artificially reproduced, -to cause the diaphragm to reproduce these words, -is another and a very different one. I venture to express -my conviction that at the beginning of his researches Professor -Bell can have had very little hope that any such -result would be obtained, notwithstanding some remarkable -experiments respecting the transmission of sound which we -can <em>now</em> very clearly perceive to point in that direction.</p> - -<p>When, however, he had invented the telephone, this -point was in effect demonstrated; for in that instrument, as -we have seen, the movements of the minute piece of metal -attached (at least in the earlier forms of the instrument) to -the centre of the receiving membrane, suffice, when precisely -copied by the similar central piece of metal in the transmitting -membrane, to cause the words which produced the -motions of the receiving or hearing membrane to be uttered -(or seem to be uttered) by the transmitting or speaking -membrane.</p> - -<p>It was reserved, however, for Edison (of New Jersey, -U.S.A., Electrical Adviser to the Western Union Telegraph -Company) to show how advantage might be taken of this -discovery to make a diaphragm speak, not directly through -the action of the movements of a diaphragm affected by -spoken words or other sounds, and therefore either simultaneously -with these or in such quick succession after them -as corresponds with the transmission of their effects along -some line of electrical or other communication, but by -the mechanical reproduction of similar movements at any -subsequent time (within certain limits at present, but probably -hereafter with practically unlimited extension as to -time).</p> - -<p>The following is slightly modified from Edison’s own -description of the phonograph:—</p> - -<p>The instrument is composed of three parts mainly; -namely, a receiving, a recording, and a transmitting apparatus.<span class="pagenum"><a id="Page_291">291</a></span> -The receiving apparatus consists of a curved tube, -one end of which is fitted with a mouthpiece. The other -end is about two inches in diameter, and is closed with a -disc or diaphragm of exceedingly thin metal, capable of -being thrust slightly outwards or vibrated upon gentle -pressure being applied to it from within the tube. To the -centre of this diaphragm (which is vertical) is fixed a small -blunt steel pin, which shares the vibratory motion of the -diaphragm. This arrangement is set on a table, and can be -adjusted suitably with respect to the second part of the -instrument—the recorder. This is a brass cylinder, about -four inches in length and four in diameter, cut with a continuous -V-groove from one end to the other, so that in effect -it represents a large screw. There are forty of these grooves -in the entire length of the cylinder. The cylinder turns -steadily, when the instrument is in operation, upon a vertical -axis, its face being presented to the steel point of the receiving -apparatus. The shaft on which it turns is provided with -a screw-thread and works in a screwed bearing, so that as -the shaft is turned (by a handle) it not only turns the -cylinder, but steadily carries it upwards. The rate of this -vertical motion is such that the cylinder behaves precisely -as if its groove worked in a screw-bearing. Thus, if the -pointer be set opposite the middle of the uppermost part of -the continuous groove at the beginning of this turning motion, -it will traverse the groove continuously to its lowest -part, which it will reach after forty turnings of the handle. -(More correctly, perhaps, we might say that the groove continuously -traverses past the pointer.) Now, suppose that a -piece of some such substance as tinfoil is wrapped round -the cylinder. Then the pointer, when at rest, just touches -the tinfoil. But when the diaphragm is vibrating under the -action of aerial waves resulting from various sounds, the -pointer vibrates in such a way as to indent the tinfoil—not -only to a greater or less depth according to the play of the -pointer to and fro in a direction square to the face of the -diaphragm, but also over a range all round its mean position,<span class="pagenum"><a id="Page_292">292</a></span> -corresponding to the play of the end of the pointer around -<em>its</em> mean position. The groove allows the pressure of the -pointer against the tinfoil free action. If the cylinder had -no groove the dead resistance of the tinfoil, thus backed up -by an unyielding surface, would stop the play of the pointer. -Under the actual conditions, the tinfoil is only kept taut -enough to receive the impressions, while yielding sufficiently -to let the play of the pointer continue unrestrained. If now -a person speaks into the receiving tube, and the handle of -the cylinder be turned, the vibrations of the pointer are impressed -upon the portion of the tinfoil lying over the hollow -groove, and are retained by it. They will be more or less -deeply marked according to the quality of the sounds -emitted, and according also, of course, to the strength with -which the speaker utters the sounds, and to the nature of -the modulations and inflexions of his voice. The result is -a message verbally imprinted upon a strip of metal. It -differs from the result in the case of Barlow’s logograph, in -being virtually a record in three dimensions instead of one -only. The varying depth of the impressions corresponds to -the varying height of the curve in Barlow’s diagrams; but -there the resemblance ceases; for that was the single feature -which Barlow’s logographs could present. Edison’s imprinted -words show, besides varying depth of impression, a -varying range on either side of the mean track of the pointer, -and also—though the eye is not able to detect this effect—there -is a varying rate of progression according as the end -of the pointer has been swayed towards or from the direction -in which, owing to the motion of the cylinder, the pointer is -virtually travelling.</p> - -<p>We may say of the record thus obtained that it is sound -presented in a visible form. A journalist who has written -on the phonograph has spoken of this record as corresponding -to the crystallization of sound. And another who, like -the former, has been (erroneously, but that is a detail) -identified with myself, has said, in like fanciful vein, that the -story of Baron Münchausen hearing words which had been<span class="pagenum"><a id="Page_293">293</a></span> -frozen during severe cold melting into speech again, so that -all the babble of a past day came floating about his ears, -has been realized by Edison’s invention. Although such -expressions may not be, and in point of fact are not, strictly -scientific, I am not disposed, for my own part, to cavil with -them. If they could by any possibility be taken <i xml:lang="fr" lang="fr">au pied de -la lettre</i> (and, by the way, we find quite a new meaning for -this expression in the light of what is now known about -vowels and consonants), there would be valid objection to -their use. But, as no one supposes that Edison’s phonograph -really crystallizes words or freezes sounds, it seems -hypercritical to denounce such expressions as the critic -of the <cite>Telegraphic Journal</cite> has denounced them.</p> - -<p>To return to Edison’s instrument.</p> - -<p>Having obtained a material record of sounds, vocal or -otherwise, it remains that a contrivance should be adopted -for making this record reproduce the sounds by which it was -itself formed. This is effected by a third portion of the -apparatus, the transmitter. This is a conical drum, or rather -a drum shaped like a frustum of a cone, having its larger -end open, the smaller—which is about two inches in -diameter—being covered with paper stretched tight like the -parchment of a drumhead. In front of this diaphragm is a -light flat steel spring, held vertically, and ending in a blunt -steel point, which projects from it and corresponds precisely -with that on the diaphragm of the receiver. The spring is -connected with the paper diaphragm by a silken thread, just -sufficiently in tension to cause the outer face of the -diaphragm to be slightly convex. Having removed the -receiving apparatus from the cylinder and set the cylinder -back to its original position, the transmitting apparatus is -brought up to the cylinder until the steel point just rests, -without pressure, in the first indentation made in the tinfoil -by the point of the receiver. If now the handle is turned at -the same speed as when the message was being recorded, -the steel point will follow the line of impression, and will -vibrate in periods corresponding to the impressions which<span class="pagenum"><a id="Page_294">294</a></span> -were produced by the point of the receiving apparatus. The -paper diaphragm being thus set into vibrations of the requisite -kind in number, depth, and side-range, there are produced -precisely the same sounds that set the diaphragm of -the receiver into vibration originally. Thus the words of -the speaker are heard issuing from the conical drum in his -own voice, tinged with a slightly metallic or mechanical tone. -If the cylinder be more slowly turned when transmitting than -it had been when receiving the message, the voice assumes -a base tone; if more quickly, the message is given with a -more treble voice. “In the present machine,” says the -account, “when a long message is to be recorded, so soon -as one strip of tinfoil is filled, it is removed and replaced by -others, until the communication has been completed. In -using the machine for the purpose of correspondence, the -metal strips are removed from the cylinder and sent to the -person with whom the speaker desires to correspond, who -must possess a machine similar to that used by the sender. -The person receiving the strips places them in turn on the -cylinder of his apparatus, applies the transmitter, and puts -the cylinder in motion, when he hears his friend’s voice -speaking to him from the indented metal. And he can repeat -the contents of the missive as often as he pleases, until -he has worn the metal through. The sender can make an -infinite number of copies of his communication by taking a -plaster-of-Paris cast of the original, and rubbing off impressions -from it on a clean sheet of foil.”</p> - -<p>I forbear from dwelling further on the interest and value -of this noble invention, or of considering some of the -developments which it will probably receive before long, -for already I have occupied more space than I had intended. -I have no doubt that in these days it will bring its inventor -less credit, and far less material gain, than would be acquired -from the invention of some ingenious contrivance for destroying -many lives at a blow, bursting a hole as large as a church -door in the bottom of an ironclad, or in some other way -helping men to carry out those destructive instincts which<span class="pagenum"><a id="Page_295">295</a></span> -they inherit from savage and brutal ancestors. But hereafter, -when the representatives of the brutality and savagery -of our nature are held in proper disesteem, and those who -have added new enjoyments to life are justly valued, a high -place in the esteem of men will be accorded to him who has -answered one-half of the poet’s aspiration,</p> - -<div class="poem-container"> -<div class="poem"><div class="stanza"> -<span class="iq">“Oh for the touch of a vanished hand,<br /></span> -<span class="i0">And the sound of a voice that is still!”<br /></span> -</div></div> -</div> - -<div class="tb">* <span class="in2">* </span><span class="in2">* </span><span class="in2">* </span><span class="in2">*</span></div> - -<p><span class="smcap">Note.</span>—Since the present paper was written, M. Aurel de Ratti has -made some experiments which he regards as tending to show that there -is no mechanical vibration. Thus, “when the cavities above and below -the iron disc of an ordinary telephone are filled with wadding, the -instrument will transmit and speak with undiminished clearness. On -placing a finger on the iron disc opposite the magnet, the instrument -will transmit and speak distinctly, only ceasing to act when sufficient -pressure is applied to bring plate and magnet into contact. Connecting -the centre of the disc by means of a short thread with an extremely -sensitive membrane, no sound is given out by the latter when a message -is transmitted. Bringing the iron cores of the double telephone in contact -with the disc, and pressing with the fingers against the plate on the -other side, a weak current from a Daniell cell produced a distinct click -in the plate, and on drawing a wire from the cell over a file which -formed part of the circuit, a rattling noise was produced in the instrument.” -If these experiments had been made before the phonograph -was invented, they would have suggested the impracticability of constructing -any instrument which would do what the phonograph actually -does, viz., cause sounds to be repeated by exciting a merely mechanical -vibration of the central part of a thin metallic disc. But as the phonograph -proves that this can actually be done, we must conclude that M. -Aurel de Ratti’s experiments will not bear the interpretation he places -upon them. They show, nevertheless, that exceedingly minute vibrations -of probably a very small portion of the telephonic disc suffice for -the distinct transmission of vocal sounds. This might indeed be inferred -from the experiments of M. Demozet, of Nantes, who finds that the -vibrations of the transmitting telephone are in amplitude little more than -1-2000th those of the receiving telephone.</p> - -<hr /> - -<p><span class="pagenum"><a id="Page_296">296</a></span></p> - -<div class="chapter"> -<h2><a id="THE_GORILLA_AND_OTHER_APES"></a><i>THE GORILLA AND OTHER APES.</i></h2> -</div> - -<p class="in0">About twenty-five centuries ago, a voyager called Hanno is -said to have sailed from Carthage, between the Pillars of -Hercules—that is, through the Straits of Gibraltar—along -the shores of Africa. “Passing the Streams of Fire,” says -the narrator, “we came to a bay called the Horn of the -South. In the recess there was an island, like the first, -having a lake, and in this there was another island full of -wild men. But much the greater part of them were women, -with hairy bodies, whom the interpreters called ‘Gorillas.’ -Pursuing them, we were not able to take the men; -they all escaped, being able to climb the precipices; -and defended themselves with pieces of rock. But three -women, who bit and scratched those who led them, were -not willing to follow. However, having killed them, we -flayed them, and conveyed the skins to Carthage; for we -did not sail any further, as provisions began to fail.”<a id="FNanchor_35" href="#Footnote_35" class="fnanchor">35</a></p> - -<p>In the opinion of many naturalists, the wild men of -this story were the anthropoid or manlike apes which are -now called gorillas, rediscovered recently by Du Chaillu. -The region inhabited by the gorillas is a well-wooded -country, “extending about a thousand miles from the Gulf -of Guinea southward,” says Gosse; “and as the gorilla is -not found beyond these limits, so we may pretty conclusively -infer that the extreme point of Hanno was somewhere<span class="pagenum"><a id="Page_297">297</a></span> -in this region.” I must confess these inferences seem -to me somewhat open to question, and the account of -Hanno’s voyage only interesting in its relation to the gorilla, -as having suggested the name now given to this race of -apes. It is not probable that Hanno sailed much further -than Sierra Leone; according to Rennell, the island where -the “wild men” were seen, was the small island lying -close to Sherbro, some seventy miles south of Sierra Leone. -To have reached the gorilla district after doubling Cape -Verd—which is itself a point considerably south of the -most southerly city founded by Hanno—he would have had -to voyage a distance exceeding that of Cape Verd from -Carthage. Nothing in the account suggests that the portion -of the voyage, after the colonizing was completed, had so -great a range. The behaviour of the “wild men,” again, -does not correspond with the known habits of the gorilla. -The idea suggested is that of a species of anthropoid ape -far inferior to the gorilla in strength, courage, and ferocity.</p> - -<p>The next accounts which have been regarded as relating -to the gorilla are those given by Portuguese voyagers. -These narratives have been received with considerable -doubt, because in some parts they seem manifestly fabulous. -Thus the pictures representing apes show also huge flying -dragons with a crocodile’s head; and we have no reason -for believing that batlike creatures like the pterodactyls of -the greensand existed in Africa or elsewhere so late as the -time of the Portuguese voyages of discovery. Purchas, in -his history of Andrew Battell, speaks of “a kinde of great -apes, if they might so bee termed, of the height of a man, -but twice as bigge in feature of their limmes, with strength -proportionable, hairie all over, otherwise altogether like men -and women in their whole bodily shape, except that their -legges had no calves.” This description accords well with -the peculiarities of gorillas, and may be regarded as the -first genuine account of these animals. Battell’s contemporaries -called the apes so described Pongoes. It is probable -that in selecting the name Pongo for the young<span class="pagenum"><a id="Page_298">298</a></span> -gorilla lately at the Westminster Aquarium, the proprietors -of this interesting creature showed a more accurate -judgment of the meaning of Purchas’s narrative than Du -Chaillu showed of Hanno’s account, in calling the great -anthropoid ape of the Gulf of Guinea a gorilla.</p> - -<p>I propose here briefly to sketch the peculiarities of the -four apes which approach nearest in form to man—the -gorilla, the chimpanzee, the orang-outang, and the gibbon; -and then, though not dealing generally with the question -of our relationship to these non-speaking (and, in some -respects, perhaps, “unspeakable”) animals, to touch on -some points connected with this question, and to point out -some errors which are very commonly entertained on the -subject.</p> - -<p>It may be well, in the first place, to point out that the -terms “ape,” “baboon,” and “monkey” are no longer -used as they were by the older naturalists. Formerly the -term “ape” was limited to tailless simians having no cheek-pouches, -and the same number of teeth as man; the term -“baboon” to short-tailed simians with dog-shaped heads; -and the term “monkey,” unless used generically, to the -long-tailed species. This was the usage suggested by Ray, -and adopted systematically thirty or forty years ago. But -it is no longer followed, though no uniform classification -has been substituted for the old arrangement. Thus Mivart -divides the apes into two classes—calling the first the -<i>Simiadæ</i>, or Old World apes; and the second the <i>Cebidæ</i>, -or New World apes. He subdivides the <i>Simiadæ</i> into (1) -the <i>Siminæ</i>, including the gorilla, chimpanzee, orang, and -gibbon; (2) the <i>Semnopithecinæ</i>; and (3) the <i>Cynopithecinæ</i>; -neither of which subdivisions will occupy much of our -attention here, save as respects the third subdivision of -the <i>Cynopithecinæ</i>, viz., the <i>Cynocephali</i>, which includes the -baboons. The other great division, the <i>Cebidæ</i>, or New -World apes, are for the most part very unlike the Old -World apes. None of them approach the gorilla or orang-outang -in size; most of them are long-tailed; and the<span class="pagenum"><a id="Page_299">299</a></span> -number and arrangement of the teeth is different. The -feature, however, which most naturalists have selected as -the characteristic distinction between the apes of the Old -World and of the New World is the position of the nostrils. -The former are called Catarhine, a word signifying that the -nostrils are directed downwards; the latter are called -Platyrhine, or broad-nosed. The nostrils of all the Old -World apes are separated by a narrow cartilaginous plate -or septum, whereas the septum of the New World apes is -broad. After the apes come, according to Mivart’s classification, -the half-apes or lemuroids.</p> - -<p>I ought, perhaps, to have mentioned that Mivart, in -describing the lemuroids as the second sub-order of a great -order of animals, the Primates, speaks of a man as (zoologically -speaking) belonging to the first sub-order. So that, -in point of fact, the two sub-orders are the Anthropoids, -including the Anthropos (man) and the Lemuroids, including -the lemur.</p> - -<p>The classification here indicated will serve our present -purpose very well. But the reader is reminded that, as -already mentioned, naturalists do not adopt at present any -uniform system of classification. Moreover, the term -<i>Simiadæ</i> is usually employed—and will be employed here—to -represent the entire simian race, <i>i.e.</i>, both the Simiadæ -and the Cebidæ of Mivart’s classification.</p> - -<p>And now, turning to the Anthropoid apes, we find ourselves -at the outset confronted by the question, Which of -the four apes, the gorilla, the orang-outang, the chimpanzee, -or the gibbon, is to be regarded as nearest to man in intelligence? -So far as bodily configuration is concerned, our -opinion would vary according to the particular feature which -we selected for consideration. But it will probably be -admitted that intelligence should be the characteristic by -which our opinions should be guided.</p> - -<p>The gibbon may be dismissed at once, though, as will -presently appear, there are some features in which this ape -resembles man more closely than either the gorilla, the orang-outang, -or the chimpanzee.</p> - -<p><span class="pagenum"><a id="Page_300">300</a></span> -The gorilla must, I fear, be summarily ejected from the -position of honour to which he has been raised by many -naturalists. Though the gorilla is a much larger animal -than the chimpanzee, his brain barely equals the chimpanzee’s -in mass. It is also less fully developed in front. -In fact Gratiolet asserts that of all the broad-chested apes, -the gorilla is—so far as brain character is concerned—the -lowest and most degraded. He regards the gorilla’s brain -as only a more advanced form of that of the brutal baboons, -while the orang’s brain is the culminating form of the gibbon -type, and the chimpanzee’s the culminating form of the -macaque type. This does not dispose of the difficulty very -satisfactorily, however, because it remains to be shown -whether the gibbon type and the macaque type are superior -as types to the baboon types. But it may suffice to remark -that the baboons are all brutal and ferocious, whereas the -gibbons are comparatively gentle animals, and the macaques -docile and even playful. It may be questioned whether -brutality and ferocity should be regarded as necessarily -removing the gorilla further from man; because it is certain -that the races of man which approach nearest to the anthropoid -apes, with which races the comparison should -assuredly be made, are characterized by these very qualities, -brutality and ferocity. Intelligence must be otherwise -gauged. Probably the average proportion of the brain’s -weight to that of the entire body, and the complexity of -the structure of the brain, would afford the best means of -deciding the question. But, unfortunately, we have very -unsatisfactory evidence on these points. The naturalists -who have based opinions on such evidence as has been -obtained, seem to overlook the poverty of the evidence. -Knowing as we do how greatly the human brain varies in -size and complexity, not only in different races, but in -different individuals of the same race, it appears unsatisfactory -in the extreme to regard the average of the -brains of each simian species hitherto examined as presenting -the true average cerebral capacity for each species.</p> - -<p><span class="pagenum"><a id="Page_301">301</a></span> -Still it seems tolerably clear that the choice as to the race -of apes which must be regarded as first in intelligence, and -therefore as on the whole the most manlike, rests between -the orang-outang and the chimpanzee. “In the world of -science, as in that of politics,” said Professor Rolleston in -1862, “France and England have occasionally differed as to -their choice between rival candidates for royalty. If either -hereditary claims or personal merits affect at all the right of -succession, beyond a question the gorilla is but a pretender, -and one or other of the two (other) candidates the true -prince. There is a graceful as well as an ungraceful way of -withdrawing from a false position, and the British public will -adopt the graceful course by accepting forthwith and henceforth -the French candidate”—the orang-outang. If this -were intended as prophecy, it has not been fulfilled by the -event, for the gorilla is still regarded by most British naturalists -as the ape which comes on the whole nearest to man; -but probably, in saying “the British public will adopt the -graceful course” in accepting the orang-outang as “the king -of the Simiadæ,” Professor Rolleston meant only that that -course would be graceful if adopted.</p> - -<p>Before the discovery of the gorilla, the chimpanzee was -usually regarded as next to man in the scale of the animal -creation. It was Cuvier who first maintained the claim of -the orang-outang to this position. Cuvier’s opinion was -based on the greater development of the orang-outang’s -brain, and the height of its forehead. But these marks of -superiority belong to the orang only when young. The -adult orang seems to be inferior, or at least not superior, to -the chimpanzee as respects cerebral formation, and in other -respects seems less to resemble man. The proportions of -his body, his long arms, high shoulders, deformed neck, and -imperfect ears are opposed to its claims to be regarded as -manlike. In all these respects, save one, the chimpanzee -seems to be greatly its superior. (The ear of the chimpanzee -is large, and not placed as with us: that of the gorilla is -much more like man’s.)</p> - -<p><span class="pagenum"><a id="Page_302">302</a></span> -As to the intelligence exhibited in the conduct of the -chimpanzee and orang-outang, various opinions may be -formed according to the various circumstances under which -the animals are observed. The following has been quoted -in evidence of the superiority of the chimpanzee in this -respect:—“About fifty years ago, a young chimpanzee and -an orang-outang of about the same age were exhibited -together at the Egyptian Hall. The chimpanzee, though in -a declining state of health, and rendered peevish and -irritable by bodily suffering, exhibited much superior marks -of intelligence to his companion; he was active, quick, and -observant of everything that passed around him; no new -visitor entered the apartment in which he was kept, and no -one left it, without attracting his attention. The orang-outang, -on the contrary, exhibited a melancholy and a disregard -of passing occurrences almost amounting to apathy; -and though in the enjoyment of better health, was evidently -much inferior to his companion in quickness and observation. -On one occasion, when the animals were dining on -potatoes and boiled chicken, and surrounded as usual with -a large party of visitors, the orang-outang allowed her plate -to be taken without exhibiting the least apparent concern. -Not so, however, the chimpanzee. We took advantage of -an opportunity when his head was turned (to observe a -person coming in) to secrete his plate also. For a few -seconds he looked round to see what had become of it, but, -not finding it, began to pout and fret exactly like a spoiled -child, and perceiving a young lady, who happened to be -standing near him, laughing, perhaps suspecting her to be the -delinquent, he flew at her in the greatest rage, and would -probably have bitten her had she not got beyond his reach. -Upon having his plate restored, he took care to prevent the -repetition of the joke by holding it firmly with one hand, -while he fed himself with the other.”</p> - -<p>This story can hardly be regarded as deciding the question -in favour of the chimpanzee. Many animals, admittedly -far inferior to the lowest order of monkeys in intelligence,<span class="pagenum"><a id="Page_303">303</a></span> -show watchfulness over their food, and as much ill-temper -when deprived of it, and as much anxiety to recover it, as -this chimpanzee did. A hundred cases in point might -readily be cited.<a id="FNanchor_36" href="#Footnote_36" class="fnanchor">36</a></p> - -<p>Perhaps the soundest opinion respecting the relative -position of the gorilla, chimpanzee, and orang-outang with -reference to man, is that which places the gorilla nearest to -the lower tribes of man now inhabiting Africa, the chimpanzee -approximating, but not so closely, to higher African -tribes, and the orang-outang approximating, but still less -closely, to Asiatic tribes. It appears to me that, whatever -weight naturalists may attach to those details in which the -gorilla and the chimpanzee are more removed from man -than the orang, no one who takes a <em>general</em> view of these -three races of anthropoid apes can hesitate to regard the -gorilla as that which, on the whole, approaches nearest to -man; but it is to a much lower race of man that the gorilla -approximates, so that the chimpanzee and the orang-outang -may fairly be regarded as higher in the scale of animal life.</p> - -<p>If we consider young specimens of the three animals, -which is, on the whole, the safest way of forming an opinion, -we are unmistakably led, in my judgment, to such a conclusion. -I have seen three or four young chimpanzees, two -young orangs, and the young gorilla lately exhibited at the -Aquarium (where he could be directly compared with the -chimpanzee), and I cannot hesitate to pronounce Pongo<span class="pagenum"><a id="Page_304">304</a></span> -altogether the most human of the three. A young chimpanzee -reminds one rather of an old man than of a child, -and the same may be said of young orangs; but the young -gorilla unmistakably reminds one of the young negro. -Repeatedly, while watching Pongo, I was reminded of the -looks and behaviour of young negroes whom I had seen in -America, though not able in every case to fix definitely -on the feature of resemblance which recalled the negro to -my mind. (The reader is, doubtless, familiar with half-remembered -traits such as those I refer to—traits, for -instance, such as assure you that a person belongs to some -county or district, though you may be unable to say what -feature, expression, or gesture suggests the idea.) One circumstance -may be specially noted, not only as frequently recurring, -but as illustrating the traits on which the resemblance -of the gorilla (when young, at any rate) to the negro depends. -A negro turns his eyes where a Caucasian would turn his -head. The peculiarity is probably a relic of savage life; for -the savage, whether engaged in war or in the chase, avoids, -as far as possible, every movement of body or limb. Pongo -looked in this way. When he thus cast his black eyes -sideways at an object I found myself reminded irresistibly -of the ways of the watchful negro waiters at an American -hotel. Certainly there is little in the movements of the -chimpanzee to remind one of any kind of human child. He -is impish; but not the most impish child of any race or tribe -ever had ways, I should suppose, resembling his.</p> - -<p>The four anthropoid apes, full grown and in their native -wilds, differ greatly from each other in character. It may -be well to consider their various traits, endeavouring to -ascertain how far diversities existing among them may be -traced to the conditions under which the four orders subsist.</p> - -<p>The gorilla occupies a well-wooded country extending -along the coast of Africa from the Gulf of Guinea southwards -across the equator. When full grown he is equal to a man -in height, but much more powerfully built. “Of specimens -shot by Du Chaillu,” says Rymer Jones, “the largest male<span class="pagenum"><a id="Page_305">305</a></span> -seems to have been at least six feet two in height; so that, -making allowance for the shortness of the lower limbs, the -dimensions of a full-grown male may be said to equal those -of a man of eight or nine feet high, and it is only in their -length that the lower limbs are disproportionate to the -gigantic trunk. In the thickness and solidity of their bones, -and in the strength of their muscles, these limbs are quite in -keeping with the rest of the body. When upright, the -gorilla’s arms reach to his knees; the hind hands are wide, -and of amazing size and power; the great toe or thumb -measures six inches in circumference; the palms and soles, -and the naked part of the face, are of an intense black -colour, as is also the breast. The other parts are thickly -clothed with hair of an iron grey, except the head, on which -it is reddish brown, and the arms, where it is long and nearly -black. The female is wholly tinged with red.”</p> - -<p>Du Chaillu gives the following account of the aspect of -the gorilla in his native woods:—“Suddenly, as we were yet -creeping along in a silence which made even a heavy breath -seem loud and distinct, the woods were at once filled with a -tremendous barking roar; then the underbrush swayed -rapidly just ahead, and presently stood before us an immense -gorilla. He had gone through the jungle on all-fours; but -when he saw our party he erected himself and looked us -boldly in the face. He stood about a dozen yards from us, -and was a sight I think I shall never forget. Nearly six feet -high (he proved four inches shorter), with immense body, -huge chest, and great muscular arms, with fiercely glaring, -large, deep-grey eyes, and a hellish expression of face, which -seemed to me some night-mare vision; thus stood before us -the king of the African forest. He was not afraid of us; he -stood there and beat his breasts with his large fists till it -resounded like an immense bass drum (which is their mode -of bidding defiance), meantime giving vent to roar after roar.”</p> - -<p>The gorilla is a fruit-eater, but as fierce as the most -carnivorous animals. He is said to show an enraged enmity -against men, probably because he has found them not only<span class="pagenum"><a id="Page_306">306</a></span> -hostile to himself, but successful in securing the fruits which -the gorilla loves, for he shows a similar hatred to the -elephant, which also seeks these fruits. We are told that -when the gorilla “sees the elephant busy with his trunk -among the twigs, he instantly regards this as an infraction of -the laws of property, and, dropping silently down to the -bough, he suddenly brings his club smartly down on the -sensitive finger of the elephant’s proboscis, and drives off -the alarmed animal trumpeting shrilly with rage and pain.” -His enmity to man is more terribly manifested. “The -young athletic negroes in their ivory-haunts,” says Gosse, -“well know the prowess of the gorilla. He does not, like -the lion, sullenly retreat on seeing them, but swings himself -rapidly down to the lower branches, courting the conflict, -and clutches the nearest of his enemies. The hideous -aspect of his visage (his green eyes flashing with rage) is -heightened by the thick and prominent brows being drawn -spasmodically up and down, with the hair erect, causing a -horrible and fiendish scowl. Weapons are torn from their -possessor’s grasp, gun-barrels bent and crushed in by the -powerful hands and vice-like teeth of the enraged brute. -More horrid still, however, is the sudden and unexpected -fate which is often inflicted by him. Two negroes will be -walking through one of the woodland paths unsuspicious of -evil, when in an instant one misses his companion, or turns -to see him drawn up in the air with a convulsed choking -cry, and in a few minutes dropped to the ground, a strangled -corpse. The terrified survivor gazes up, and meets the grin -and glare of the fiendish giant, who, watching his opportunity, -had suddenly put down his immense hind hand, -caught the wretch by the neck with resistless power, and -dropped him only when he ceased to struggle.”</p> - -<p>The chimpanzee inhabits the region from Sierra Leone -to the southern confines of Angola, possibly as far as Cape -Negro, so that his domain includes within it that of the -gorilla. He attains almost the same height as the gorilla -when full grown, but is far less powerfully built. In fact, in<span class="pagenum"><a id="Page_307">307</a></span> -general proportions the chimpanzee approaches man more -nearly than does any other animal. His body is covered -with long black coarse hair, thickest on the head, shoulders, -and back, and rather thin on the breast and belly. The -face is dark brown and naked, as are the ears, except that -long black whiskers adorn the animal’s cheeks. The hair -on the forearms is directed towards the elbows, as is the case -with all the anthropoid apes, and with man himself. This -hair forms, where it meets the hair from the upper arm, a -small ruff about the elbow joint. The chimpanzees live in -society in the woods, constructing huts from the branches -and foliage of trees to protect themselves against the sun -and heavy rains. It is said by some travellers that the -chimpanzee walks upright in its native woods, but this is -doubtful; though certainly the formation of the toes better -fits them to stand upright than either the gorilla or the orang. -They arm themselves with clubs, and unite to defend themselves -against the attacks of wild beasts, “compelling,” it is -said, “even the elephant himself to abandon the districts in -which they reside.” We learn that “it is dangerous for men -to enter their forests, unless in companies and well armed; -women in particular are often said to be carried away by -these animals, and one negress is reported to have lived -among them for the space of three years, during which time -they treated her with uniform kindness, but always prevented -any attempt on her part to escape. When the negroes -leave a fire in the woods, it is said that the chimpanzees will -gather round and warm themselves at the blaze, but they -have not sufficient intelligence to keep it alive by fresh -supplies of fuel.”</p> - -<p>The orang-outang inhabits Borneo, Java, Sumatra, and -other islands of the Indian coast. He attains a greater -height than the gorilla, but, though very powerful and active, -would probably not be a match for the gorilla in a single -combat. His arms are by comparison as well as actually -much longer. Whereas the gorilla’s reach only to the knees, -the arms of the orang-outang almost reach the ground when<span class="pagenum"><a id="Page_308">308</a></span> -the animal is standing upright. The orang does not often -assume an upright attitude, however. “It seldom attempts -to walk on the hind feet alone, and when it does the hands -are invariably employed for the purpose of steadying its -tottering equilibrium, touching the ground lightly on each -side as it proceeds, and by this means recovering the lost -balance of the body.” The gorilla uses his hands differently. -He can scarcely be said to walk on all-fours, because he -does not place the inside of the hand on the ground, but -walks on the knuckles, evidently trying to keep the fore part -of the body as high as possible. “The muzzle is somewhat -long, the mouth ill-shaped, the lips thin and protuberant; -the ears are very small, the chin scarcely recognizable, and -the nose only to be recognized by the nostrils. The face, -ears, and inside of the hands of the orang are naked and of -a brick-red colour; the fore parts are also but thinly covered -with hair; but the head, shoulders, back, and extremities -are thickly clothed with long hair of dark wine-red colour, -directed forwards on the crown of the head and upwards -towards the elbows on the forearms.”</p> - -<p>The orang-outang changes remarkably in character and -appearance as he approaches full growth. “Though exhibiting -in early youth a rotundity of the cranium and a height of -forehead altogether peculiar, and accompanied at the same -time with a gentleness of disposition and a gravity of -manners which contrast strongly with the petulant and -irascible temper of the lower orders of quadrumanous mammals, -the orang-outang in its adult state is even remarkable -for the flatness of its retiring forehead, the great development -of the superorbital and occipital crests, the prominence -of its jaws, the remarkable size of its canine teeth, and the -whole form of the skull, which from the globular shape of -the human head, as in the young specimen, assumes all the -forms and characters belonging to that of a large carnivorous -animal. The extraordinary contrasts thus presented in the -form of the skull at different epochs of the same animal’s -life were long considered as the characters of distinct species;<span class="pagenum"><a id="Page_309">309</a></span> -nor was it till intermediate forms were obtained, exhibiting -in some degree the peculiarities of both extremes, that they -were finally recognized as distinguishing different periods of -growth only.”</p> - -<p>Unlike the gorilla, which attacks man with peculiar -malignity, and the chimpanzee, which when in large troops -assails those who approach its retreats, the orang, even in -its adult state, seems not to be dangerous unless attacked. -Even then he does not always show great ferocity. The -two following anecdotes illustrate well its character. The -first is from the pen of Dr. Abel Clarke (fifth volume of the -“Asiatic Researches”); the other is from Wallace’s interesting -work, “The Malay Archipelago.” An orang-outang -fully seven feet high was discovered by the company of a -merchant ship, at a place called Ramboon, on the north-west -coast of Sumatra, on a spot where there were few trees -and little cultivated ground. “It was evident that he had -come from a distance, for his legs were covered with mud up -to the knees, and the natives were unacquainted with him. -On the approach of the boat’s crew he came down from the -tree in which he was discovered, and made for a clump at -some distance; exhibiting, as he moved, the appearance of -a tall man-like figure, covered with shining brown hair, -walking erect, with a waddling gait, but sometimes accelerating -his motion with his hands, and occasionally impelling -himself forward with the bough of a tree. His motion on -the ground was evidently not his natural mode of progression, -for, even when assisted by his hands and the bough, it was -slow and vacillating; it was necessary to see him among the -trees to estimate his strength and agility. On being driven -to a small clump, he gained by one spring a very lofty -branch and bounded from one branch to another with the -swiftness of a common monkey, his progress being as rapid -as that of a swift horse. After receiving five balls his exertions -relaxed, and, reclining exhausted against a branch, -he vomited a quantity of blood. The ammunition of the -hunters being by this time exhausted, they were obliged to<span class="pagenum"><a id="Page_310">310</a></span> -fell the tree in order to obtain him; but what was their surprise -to see him, as the tree was falling, effect his retreat to -another, with seemingly undiminished vigour! In fact, they -were obliged to cut down all the trees before they could -force him to combat his enemies on the ground, and when -finally overpowered by numbers, and nearly in a dying state, -he seized a spear made of supple wood, which would have -withstood the strength of the stoutest man, and broke it like -a reed. It was stated, by those who aided in his death, that -the human-like expression of his countenance and his piteous -manner of placing his hands over his wounds, distressed -their feelings so as almost to make them question the nature -of the act they were committing. He was seven feet high, -with a broad expanded chest and narrow waist. His chin -was fringed with a beard that curled neatly on each side, -and formed an ornamental rather than a frightful appendage -to his visage. His arms were long even in proportion to his -height, but his legs were much shorter. Upon the whole, he -was a wonderful beast to behold, and there was more about -him to excite amazement than fear. His hair was smooth -and glossy, and his whole appearance showed him to be in -the full vigour of his youth and strength.” On the whole, -the narrative seems to suggest a remark similar to one -applied by Washington Irving to the followers of Ojeda and -their treatment of the (so-called) Indians of South America, -“we confess we feel a momentary doubt whether the arbitrary -appellation of ‘brute’ is always applied to the right party.”</p> - -<p>The other story also presents man as at least as brutal as -the orang concerned in the event. “A few miles down the -river,” says Wallace, “there is a Dyak house, and the inhabitants -saw a large orang feeding on the young shoots of a -palm by the river-side. On being alarmed he retreated -towards the jungle which was close by, and a number of the -men, armed with spears and choppers, ran out to intercept -him. The man who was in front tried to run his spear -through the animal’s body; but the orang seized it in his -hands, and in an instant got hold of the man’s arm, which<span class="pagenum"><a id="Page_311">311</a></span> -he seized in his mouth, making his teeth meet in the flesh -above the elbow, which he tore and lacerated in a dreadful -manner. Had not the others been close behind, the man -would have been more seriously injured, if not killed, as he -was quite powerless; but they soon destroyed the creature -with their spears and choppers. The man remained ill for -a long time, and never fully recovered the use of his arm.”</p> - -<p>The term gibbon includes several varieties of tail-less, -long-armed, catarhine apes. The largest variety, called the -siamang, need alone be described here.</p> - -<p>The siamang inhabits Sumatra. It presents several points -of resemblance to the orang-outang, but is also in several -respects strongly distinguished from that animal. The arms -are longer even than the orang’s, and the peculiar use which -the orang makes of his long arms is more strikingly shown -in the progression of the long-armed siamang, for the body -inclining slightly forward, when the animal is on level ground -the long arms are used somewhat like crutches, and they -advance by jerks resembling the hobbling of a lame man -whom fear compels to make an extraordinary effort. The -skull is small, and much more depressed than that of the -orang or chimpanzee. The face is naked and black, straggling -red hairs marking the eyebrows. The eyes are deeply -sunk, a peculiarity which, by the way, seems characteristic -of arboreal creatures generally;<a id="FNanchor_37" href="#Footnote_37" class="fnanchor">37</a> the nose broad and flat,<span class="pagenum"><a id="Page_312">312</a></span> -with wide-open nostrils; the cheeks sunk under high cheekbones; -the chin almost rudimentary. “The hair over the -whole body is thick, long, and of a glossy black colour, -much closer on the shoulders, back, and limbs than on the -belly, which, particularly in the females, is nearly naked. -The ears are entirely concealed by the hair of the head; -they are naked, and, like all the other naked parts, of a deep -black colour. Beneath the chin there is a large, bare sac, -of a lax and oily appearance, which is distended with air -when the animal cries, and in that state resembles an enormous -goitre. It is similar to that possessed by the orang-outang, -and undoubtedly assists in swelling the volume of the voice, -and producing those astounding cries which, according to -Duvancelle’s account, may be heard at the distance of several -miles.” This, however, may be doubted, for M. Duvancelle -himself remarks of the wouwou, that, “though deprived of -the guttural sac so remarkable in the siamang, its cry is -very nearly the same; so that it would appear that this organ -does not produce the effect of increasing the sound usually -attributed to it, or else that it must be replaced in the wouwou -by some analogous formation.”</p> - -<p>The habits of the siamang are interesting, especially in -their bearing on the relationship between the various orders -of anthropoid apes and man; for, though the gibbon is -unquestionably the lowest of the four orders of the anthropoid -apes in intelligence, it possesses some characteristics -which bring it nearer to man (so far as they are concerned) -than any of its congeners. The chief authorities respecting -the ways of the siamang are the French naturalists Diard -and Duvancelle, and the late Sir Stamford Raffles.</p> - -<p>The siamangs generally assemble in large troops, -“conducted, it is said, by a chief, whom the Malays believe -to be invulnerable, probably because he is more agile, -powerful, and difficult to capture than the rest.” “Thus -united,” proceeds M. Duvancelle (in a letter addressed to -Cuvier), “the siamangs salute the rising and the setting sun -with the most terrific cries” (like sun-worshippers), “which<span class="pagenum"><a id="Page_313">313</a></span> -may be heard at the distance of many miles, and which, -when near, stun when they do not frighten. This is the -morning call of the mountain Malays; but to the inhabitants -of the town, who are unaccustomed to it, it is an unsupportable -annoyance. By way of compensation, the siamangs -keep a profound silence during the day, unless when interrupted -in their repose or their sleep. They are slow and -heavy in their gait, wanting confidence when they climb -and agility when they leap, so that they may be easily -caught when they can be surprised. But nature, in depriving -them of the means of readily escaping danger, has -endowed them with a vigilance which rarely fails them; -and if they hear a noise which is unusual to them, even at -the distance of a mile, fright seizes them and they immediately -take flight. When surprised on the ground, however, -they may be captured without resistance, either overwhelmed -with fear or conscious of their weakness and the impossibility -of escaping. At first, indeed, they endeavour to avoid -their pursuers by flight, and it is then that their want of skill -in this exercise becomes most apparent.”</p> - -<p>“However numerous the troop may be, if one is -wounded it is immediately abandoned by the rest, unless, -indeed, it happen to be a young one. Then the mother, -who either carries it or follows close behind, stops, falls -with it, and, uttering the most frightful cries, precipitates -herself upon the common enemy with open mouth and arms -extended. But it is manifest that these animals are not -made for combat; they neither know how to deal nor to -shun a blow. Nor is their maternal affection displayed -only in moments of danger. The care which the females -bestow upon their offspring is so tender and even refined, -that one would be almost tempted to attribute the sentiment -to a rational rather than an instinctive process. It is a -curious and interesting spectacle, which a little precaution -has sometimes enabled me to witness, to see these females -carry their young to the river, wash their faces in spite of -their outcries, wipe and dry them, and altogether bestow<span class="pagenum"><a id="Page_314">314</a></span> -upon their cleanliness a time and attention that in many -cases the children of our own species might well envy. The -Malays related a fact to me, which I doubted at first, but -which I consider to be in a great measure confirmed by my -own subsequent observations. It is that the young siamangs, -whilst yet too weak to go alone, are always carried by -individuals of their own sex, by their fathers if they are -males, and by their mothers if females. I have also been -assured that these animals frequently become the prey of -the tiger, from the same species of fascination which serpents -are said to exercise over birds, squirrels, and other small -animals. Servitude, however long, seems to have no effect -in modifying the characteristic defects of this ape—his -stupidity, sluggishness, and awkwardness. It is true that a -few days suffice to make him as gentle and contented as he -was before wild and distrustful; but, constitutionally timid, -he never acquires the familiarity of other apes, and even his -submission appears to be rather the result of extreme apathy -than of any degree of confidence or affection. He is almost -equally insensible to good or bad treatment; gratitude and -revenge are equally strange to him.”</p> - -<p>We have next to consider certain points connected with -the theory of the relationship between man and the anthropoid -apes. It is hardly necessary for me to say, perhaps, -that in thus dealing with a subject requiring for its -independent investigation the life-long study of departments -of science which are outside those in which I have -taken special interest, I am not pretending to advance my -opinion as of weight in matters as yet undetermined by -zoologists. But it has always seemed to me, that when -those who have made special study of a subject collect and -publish the result of their researches, and a body of evidence -is thus made available for the general body scientific, the -facts can be advantageously considered by students of other -branches of science, so only that, in leaving for a while -their own subject, they do not depart from the true scientific -method, and that they are specially careful to distinguish<span class="pagenum"><a id="Page_315">315</a></span> -what has been really ascertained from what is only surmised -with a greater or less degree of probability.</p> - -<p>In the first place, then, I would call attention to some -very common mistakes respecting the Darwinian theory of -the Descent of Man. I do not refer here to ordinary -misconceptions respecting the theory of natural selection. -To say the truth, those who have not passed beyond <em>this</em> -stage of error,—those who still confound the theory of natural -selection with the Lamarckian and other theories (or rather -hypotheses<a id="FNanchor_38" href="#Footnote_38" class="fnanchor">38</a>) of evolution,—are not as yet in a position to -deal with our present subject, and may be left out of consideration.</p> - -<p>The errors to which I refer are in the main included in -the following statement. It is supposed by many, perhaps -by most, that according to Darwin man is descended from -one or other of the races of anthropoid apes; and that the -various orders and sub-orders of apes and monkeys at -present existing can be arranged in a series gradually -approaching more and more nearly to man, and indicating -the various steps (or some of them, for gaps exist in the -series) by which man was developed. Nothing can be -plainer, however, than Darwin’s contradiction of this -genealogy for the human races. Not only does he not for -a moment countenance the belief that the present races of -monkeys and apes can be arranged in a series gradually -approximating more and more nearly to man, not only does -he reject the belief that man is descended from any present -existing anthropoid ape, but he even denies that the progenitor -of man resembled any known ape. “We must not -fall into the error of supposing,” he says, “that the early<span class="pagenum"><a id="Page_316">316</a></span> -progenitor of the whole simian stock, including man, was -identical with, or even closely resembled, any existing ape -or monkey.”</p> - -<p>It appears to me, though it may seem somewhat bold to -express this opinion of the views of a naturalist so deservedly -eminent as Mr. Mivart, that in his interesting little treatise, -“Man and Apes,”—a treatise which may be described as -opposed to Darwin’s special views but not generally -opposed to the theory of evolution,—he misapprehends -Darwin’s position in this respect. For he arrives at the -conclusion that if the Darwinian theory is sound, then “low -down” (<i>i.e.</i>, far remote) “in the scale of Primates” (tri-syllabic) -“was an ancestral form so like man that it might -well be called an <em>homunculus</em>; and we have the virtual pre-existence -of man’s body supposed, in order to account for -the actual first appearance of that body as we know it—a -supposition manifestly absurd if put forward as an explanation.”<a id="FNanchor_39" href="#Footnote_39" class="fnanchor">39</a></p> - -<p>How, then, according to the Darwinian theory, is man -related to the monkey? The answer to this question is -simply that the relationship is the same in kind, though not -the same in degree, as that by which the most perfect -Caucasian race is related to the lowest race of Australian, -or Papuan, or Bosjesman savages. No one supposes that -one of these races of savages could by any process of evolution, -however long-continued, be developed into a race -resembling the Caucasian in bodily and mental attributes.<span class="pagenum"><a id="Page_317">317</a></span> -Nor does any one suppose that the savage progenitor of the -Caucasian races was identical with, or even closely -resembled, any existing race of savages. Yet we recognize -in the lowest forms of savage man our blood relations. In -other words, it is generally believed that if our genealogy, -and that of any existing race of savages, could be traced -back through all its reticulations, we should at length reach -a race whose blood we share with that race. It is also -generally believed (though for my own part I think the -logical consequences of the principle underlying all theories -of evolution is in reality opposed to the belief) that, by -tracing the genealogical reticulations still further back, we -should at length arrive at a single race from which all the -present races of man and no other animals have descended. -The Darwinian faith with respect to men and monkeys is -precisely analogous. It is believed that the genealogy of -every existent race of monkeys, if traced back, would lead -us to a race whose blood we share with that race of monkeys; -and—which is at once a wider and a more precise proposition—that, -as Darwin puts it, “the two main divisions of -the Simiadæ, namely, the catarhine and platyrhine monkeys, -with their sub-groups, have all proceeded from some one -extremely ancient progenitor.” This proposition is manifestly -wider. I call it also more precise, because it implies, -and is evidently intended by Darwin to signify, that from -that extremely ancient progenitor no race outside the two -great orders of Simiadæ have even partially <em>descended</em>, though -other races share with the Simiadæ descent from some still -more remote race of progenitors.</p> - -<p>This latter point, however, is not related specially to the -common errors respecting the Darwinian theory which I -have indicated above, except in so far as it is a detail of the -actual Darwinian theory. I would, in passing, point out -that, like the detail referred to in connection with the relationship -of the various races of man, this one is not logically -deducible from the theory of evolution. In fact, I have -sometimes thought that the principal difficulties of that<span class="pagenum"><a id="Page_318">318</a></span> -theory arise from this unnecessary and not logically sound -doctrine. I pointed out, rather more than three years ago, -in an article “On some of our Blood Relations,” in a weekly -scientific journal, that the analogy between the descent of -races and the descent of individual members of any race, -requires us rather to believe that the remote progenitor of -the human race and the Simiadæ has had its share—though -a less share—in the generation of other races related to these -in more or less remote degrees. I may perhaps most conveniently -present the considerations on which I based this -conclusion, by means of a somewhat familiar illustration:—</p> - -<p>Let us take two persons, brother and sister (whom let -us call the pair A), as analogues of the human race. Then -these two have four great-grandparents on the father’s side, -and four on the mother’s side. All these may be regarded -as equally related to the pair A. Now, let us suppose that -the descendants of the four families of great-grandparents -intermarry, no marriages being in any case made outside -these families, and that the descendants in the same generation -as the pair A are regarded as corresponding to the -entire order of the Simiadæ, the pair A representing, as -already agreed, the race of man, and all families outside the -descendants of the four great-grandparental families corresponding -to orders of animals more distantly related than -the Simiadæ to man. Then we have what corresponds (so -far as our illustration is concerned) to Darwin’s views respecting -man and the Simiadæ, and animals lower in the -scale of life. The first cousins of the pair A may be taken -as representing the anthropoid apes; the second cousins as -representing the lemurs or half-apes; the third cousins as -representing the platyrhine or American apes. The entire -family—including the pair A, representing man—is descended -also, in accordance with the Darwinian view, from a single -family of progenitors, no outside families sharing <em>descent</em>, -though all share <em>blood</em>, with that family.</p> - -<p>But manifestly, this is an entirely artificial and improbable -arrangement in the case of families. The eight grandparents<span class="pagenum"><a id="Page_319">319</a></span> -<em>might</em> be so removed in circumstances from surrounding -families—so much superior to them, let us say—that -neither they nor any of their descendants would intermarry -with these inferior families: and thus none of their -great-grandchildren would share descent from some other -stock contemporary with the great-grandparents; or—which -is the same thing, but seen in another light—none of the -contemporaries of the great-grandchildren would share descent -from the eight grandparents. But so complete a -separation of the family from surrounding families would be -altogether exceptional and unlikely. For, even assuming -the eight families to be originally very markedly distinguished -from all surrounding families, yet families rise and -fall, marry unequally, and within the range of a few generations -a wide disparity of blood and condition appears among -the descendants of any group of families. So that, in point -of fact, the relations assumed to subsist between man, the -Simiadæ, and lower animal forms, corresponds to an unusual -and improbable set of relations among families of several -persons. Either, then, the relations of families must be regarded -as not truly analogous to the relations of races, which -no evolutionist would assert, or else we must adopt a somewhat -different view of the relationship between man, the -Simiadæ, and inferior animals.</p> - -<p>One other illustration may serve not only to make my -argument clearer, but also, by presenting an actual case, to -enforce the conclusion to which it points.</p> - -<p>We know that the various races of man are related together -more or less closely, that some are purer than others, -and that one or two claim almost absolute purity. Now, if -we take one of these last, as, for instance, the Jewish race, -and trace the race backwards to its origin, we find it, according -to tradition, carried back to twelve families, the twelve -sons of Jacob and their respective wives. (We cannot go -further back because the wives of Jacob’s sons must be -taken into account, and they were not descended from -Abraham or Isaac and their wives only,—in fact, could not<span class="pagenum"><a id="Page_320">320</a></span> -have been.) If the descendants of those twelve families -had never intermarried with outside families in such sort -that the descendants of such mixed families came to be -regarded as true Hebrews, we should have in the Hebrews a -race corresponding to the Simiadæ as regarded by Darwin, -<i>i.e.</i>, a race entirely descended from one set of families, and -so constituting, in fact, a single family. But we know that, -despite the objections entertained by the Hebrews against -the intermixture of their race with other races, this did not -happen. Not only did many of those regarded as true -Hebrews share descent from nations outside their own, but -many of those regarded as truly belonging to nations outside -the Jewish race shared descent from the twelve sons of -Jacob.</p> - -<p>The case corresponding, then, to that of the purest of all -human races, and the case therefore most favourable to the -view presented by Darwin (though very far from essential to -the Darwinian theory), is simply this, that, in the first place, -many animals regarded as truly Simiadæ share descent from -animals outside that family which Darwin regards as the ape -progenitor of man; and, in the second place, many animals -regarded as outside the Simiadæ share descent from that -ape-like progenitor. This involves the important inference -that the ape-like progenitor of man was not so markedly -differentiated from other families of animals then existing, -that fertile intercourse was impossible. A little consideration -will show that this inference accords well with, if it might -not almost have been directly deduced from, the Darwinian -doctrine that all orders of mammals were, in turn, descended -from a still more remote progenitor race. The same considerations -may manifestly be applied also to that more -remote race, to the still more remote race from which all the -vertebrates have descended, and so on to the source itself -from which all forms of living creatures are supposed to -have descended. A difficulty meets us at that remotest end -of the chain analogous to the difficulty of understanding how -life began at all; but we should profit little by extending<span class="pagenum"><a id="Page_321">321</a></span> -the inquiry to these difficulties, which remain, and are likely -long to remain, insuperable.</p> - -<p>So far, however, are the considerations above urged from -introducing any new or insuperable objection to the Darwinian -theory, that, rightly understood, they indicate the -true answer to an objection which has been urged by Mivart -and others against the belief that man has descended from -some ape-like progenitor.</p> - -<p>Mivart shows that no existing ape or monkey approaches -man more nearly in all respects than other races, but that -one resembles man more closely in some respects, another -in others, a third in yet others, and so forth. “The ear -lobule of the gorilla makes him our cousin,” he says, “but -his tongue is eloquent in his own dispraise.” If the “bridging -convolutions of the orang[’s brain] go to sustain his -claim to supremacy, they also go far to sustain a similar -claim on the part of the long-tailed thumbless spider-monkeys. -If the obliquely ridged teeth of <i>Simia</i> and <i>Troglodytes</i> -(the chimpanzee) point to community of origin, how -can we deny a similar community of origin, as thus estimated, -to the howling monkeys and galagos? The liver of -the gibbons proclaims them almost human; that of the -gorilla declares him comparatively brutal. The lower -American apes meet us with what seems the ‘front of Jove -himself,’ compared with the gigantic but low-browed denizens -of tropical Western Africa.”</p> - -<p>He concludes that the existence of these wide-spread -signs of affinity and the associated signs of divergence, disprove -the theory that the structural characters existing in -the human frame have had their origin in the influence of -inheritance and “natural selection.” “In the words of the -illustrious Dutch naturalists, Messrs. Schroeder, Van der -Kolk and Vrolik,” he says, “the lines of affinity existing -between different Primates construct rather a network than -a ladder. It is indeed a tangled web, the meshes of which -no naturalist has as yet unravelled by the aid of natural -selection. Nay, more, these complex affinities form such a<span class="pagenum"><a id="Page_322">322</a></span> -net for the use of the teleological <i xml:lang="la" lang="la">retiarius</i> as it will be -difficult for his Lucretian antagonist to evade, even with the -countless turns and doublings of Darwinian evolutions.”</p> - -<p>It appears to me that when we observe the analogy between -the relationships of individuals, families, and races of -man, and the relationships of the various species of animals, -the difficulty indicated by Mr. Mivart disappears. Take, for -instance, the case of the eight allied families above considered. -Suppose, instead of the continual intermarriages -before imagined—an exceptional order of events, be it remembered—that -the more usual order of things prevails, -viz., that alliances take place with other families. For simplicity, -however, imagine that each married pair has two -children, male and female, and that each person marries -once and only once. Then it will be found that the pair A -have ten families of cousins, two first-cousin families, and -eight second-cousin families; these are all the families which -share descent from the eight great-grandparents of the pair. -(To have third-cousin families we should have to go back to -the fourth generation.) Thus there are eleven families in -all. Now, in the case first imagined of constant intermarrying, -there would still have been eleven families, but they -would all have descended from eight great-grandparents, -and we should then expect to find among the eleven families -various combinations, so to speak, of the special characteristics -of the eight families from which they had descended. -On the other hand, eleven families, in <em>no</em> way connected, -have descended from eighty-eight great-grandparents, and -would present a corresponding variety of characteristics. -But in the case actually supposed, in which the eleven -families are so related that each one (for what applies to the -pair A applies to the others) has two first-cousin families, -and eight second-cousin families, it will be found that instead -of 88 they have only 56 great-grandparents, or ancestors, in -the third generation above them. The two families related -as first cousins to the pair A have, like these, eight great-grandparents, -four out of these eight for one family, being<span class="pagenum"><a id="Page_323">323</a></span> -the four grandparents of the father of the pair A, the other -four being outsiders; while four of the eight great-grandparents -of the other family of first cousins are the four -grandparents of the mother of the pair A, the other four -being outsiders. The other eight families each have eight -great-grandparents; two of the families having among their -great-grandparents the parents of one of the grandfathers of -the pair A, but no other great-grandparent in common with -the pair A; other two of the eight families having among -their great-grandparents the parents of the other grandfather -of the pair A; other two having among their great-grandparents -the parents of one of the grandmothers of the -pair A; the remaining two families having among their -great-grandparents the parents of the other grandmother of -the pair A; while in all cases the six remaining great-grandparents -of each family are outsiders, in no way related, on -our assumption, either to the eight great-grandparents of the -pair A or to each other, except as connected in pairs by -marriage.</p> - -<p>Now manifestly in such a case, which, save for the -symmetry introduced to simplify its details, represents fairly -the usual relationships between any family, its first cousins, -and its second cousins, we should not expect to find any one -of the ten other families resembling the pair A more closely -in <em>all</em> respects than would any other of the ten. The two -first-cousin families would <em>on the whole</em> resemble the pair A -more nearly than would any of the other eight, but we should -expect to find <em>some</em> features or circumstances in which one or -other or all of the second-cousin families would show a -closer resemblance to one or other or both of the pair A. -This is found often, perhaps generally, to be the case, even -as respects the ordinary characteristics in which resemblance -is looked for, as complexion, height, features, manner, disposition, -and so forth. Much more would it be recognized, -if such close investigation could be made among the various -families as the naturalist can make into the characteristics of -men and animals. The fact, then, that features of resemblance<span class="pagenum"><a id="Page_324">324</a></span> -to man are found, not all in one order of the -Simiadæ, but scattered among the various orders, is perfectly -analogous with the laws of resemblance recognized among -the various members of more or less closely related families.</p> - -<p>The same result follows if we consider the analogy between -various different species of animals on the one hand -and between various races of the human family on the other. -No one thinks of urging against the ordinary theory that -men form only a single species, the objection that none of -the other families of the human race can be regarded as the -progenitor of the Caucasian family, seeing that though the -Mongolian type is nearer in some respects, the Ethiopian is -nearer in others, the American in others, the Malay in yet -others. We find in this the perfect analogue of what is recognized -in the relationships between families all belonging to -one nation, or even to one small branch of a nation. Is it -not reasonable, then, to find in the corresponding features -of scattered resemblance observed among the various -branches of the great Simian family, not the objection which -Mivart finds against the theory of relationship, but rather -what should be expected if that theory is sound, and therefore, -<i xml:lang="la" lang="la">pro tanto</i>, a confirmation of the theory?</p> - -<p>But now, in conclusion, let us briefly consider the great -difficulty of the theory that man is descended from some -ape-like, arboreal, speechless animal,—the difficulty of bridging -over the wide gap which confessedly separates the lowest -race of savages from the highest existing race of apes. After -all that has been done to diminish the difficulty, it remains -a very great one. It is quite true that what is going on at -this present time shows how the gap has been widened, and -therefore indicates how it may once have been comparatively -small. The more savage races of man are gradually disappearing -on the one hand, the most man-like apes are being -destroyed on the other,—so that on both sides of the great -gap a widening process is at work. Ten thousand years -hence the least civilized human race will probably be little -inferior to the average Caucasian races of the present day,<span class="pagenum"><a id="Page_325">325</a></span> -the most civilized being far in advance of the most advanced -European races of our time. On the other hand, the gorilla, -the chimpanzee, the orang-outang, and the gibbon will probably -be extinct or nearly so. True, the men of those days -will probably have very exact records of the characteristics -not only of the present savage races of man, but of the present -races of apes. Nay, they will probably know of intermediate -races, long since extinct even now, whose fossil -remains geologists hope to discover before long as they have -already discovered the remains of an ape as large as man -(the <i>Dryopithecus</i>) which existed in Europe during the -Miocene period;<a id="FNanchor_40" href="#Footnote_40" class="fnanchor">40</a> and more recently the remains of a race -of monkeys akin to Macacus, which once inhabited Attica. -But although our remote descendants will thus possess -means which we do not possess of bridging the gap between -the highest races of apes and the lowest races of man, the -gap will nevertheless be wider in their time. And tracing -backwards the process, which, thus traced forward, shows a -widened gap, we see that once the gap must have been much -narrower than it is. Lower races of man than any now -known once existed on the earth, and also races of apes -nearer akin to man than any now existing, even if the present -races of apes are not the degraded descendants of races -which, living under more favourable conditions, were better -developed after their kind than the gorilla, chimpanzee, -orang, and gibbon of the present time.</p> - -<p>It may be, indeed, that in the consideration last suggested -we may find some assistance in dealing with our difficult -problem. It is commonly assumed that the man-like -apes are the most advanced members of the Simian family -save man alone, and so far as their present condition is concerned -this may be true. But it is not necessarily the case<span class="pagenum"><a id="Page_326">326</a></span> -that the anthropoid apes have advanced to their present -condition. Judging from the appearance of the young of -these races, we may infer with some degree of probability -that these apes are the degraded representatives of more intelligent -and less savage creatures. Whereas the young of -man is decidedly more savage in character than the well-nurtured -and carefully trained adult, the young of apes are decidedly -less savage than the adult. The same reasoning which -leads us to regard the wildness, the natural cruelty, the destructiveness, -the love of noise, and many other little ways -of young children, as reminders of a more or less remote -savage ancestry, should lead us to regard the comparative -tameness and quiet of the young gorilla, for example, as -evidence that in remote times the progenitors of the race -were not so wild and fierce as the present race of gorillas.</p> - -<p>But even when all such considerations, whether based on -the known or the possible, have been taken into account, -the gap between the lowest savage and the highest ape is not -easily bridged. It is easier to see how man <em>may</em> have -developed from an arboreal, unspeaking animal to his present -state, than to ascertain how any part of the development -was actually effected; in other words, it is easier to suggest -a general hypothesis than to establish an even partial -theory.</p> - -<p>That the progenitor of man was arboreal in his habits -seems altogether probable. Darwin recognizes in the -arrangement of the hair on the human forearm the strongest -evidence on this point, so far as the actual body of man is -concerned; the remaining and perhaps stronger evidence -being derived from appearances recognized in the unborn -child. He, who usually seems as though he could overlook -nothing, seems to me to have overlooked a peculiarity which -is even more strikingly suggestive of original arboreal habits. -There is one set of muscles, and, so far as I know, one -only, which the infant uses freely, while the adult scarcely -uses them at all. I mean the muscles which separate the -toes, and those, especially, which work the big toe. Very<span class="pagenum"><a id="Page_327">327</a></span> -young children not only move the toes apart, so that the -great toe and the little toe will be inclined to each other (in -the plane of the sole) nearly ninety degrees, but also distinctly -clutch with the toes. The habit has no relation to -the child’s actual means of satisfying its wants. I have -often thought that the child’s manner of clutching with its -fingers is indicative of the former arboreal habits of the -race, but it is not difficult to explain the action otherwise. -The clutching movement of the toes, however, cannot be so -explained. The child can neither bring food to its mouth -in this way nor save itself from falling; and as the adult -does not use the toes in this way the habit cannot be regarded -as the first imperfect effort towards movements subsequently -useful. In fact, the very circumstance that the -movement is gradually disused shows that it is useless to the -human child in the present condition of the race. In the -very young gorilla the clutching motion of the toes is -scarcely more marked than it is in a very young child; only -in the gorilla the movement, being of use, is continued by -the young, and is developed into that effective clutch with -the feet which has been already described. Here we have -another illustration of that divergency which, rather than -either simple descent or ascent, characterizes the relationship -between man and the anthropoid ape. In the growing -gorilla a habit is more and more freely used, which is more -and more completely given up by the child as he progresses -towards maturity.</p> - -<p>Probably the arboreal progenitor of man was originally -compelled to abandon his arboreal habits by some slow -change in the flora of his habitat, resulting in the diminution -and eventual disappearance of trees suited for his movements. -He would thus be compelled to adopt, at first, -some such course as the chimpanzee—making huts of such -branches and foliage as he could conveniently use for the -purpose. The habit of living in large companies would (as -in the case of the chimpanzee) become before long necessary, -especially if the race or races thus driven from their former<span class="pagenum"><a id="Page_328">328</a></span> -abode in the trees were, like the gibbons, unapt when alone -both in attack and in defence. One can imagine how the -use of vocal signals of various kinds would be of service to -the members of these troops, not only in their excursions, -but during the work of erecting huts or defences against -their enemies. If in two generations the silent wild dog -acquires, when brought into the company of domestic dogs, -no less than five distinct barking signals, we can well believe -that a race much superior in intelligence, and forced by -necessity to associate in large bodies, would—in many -hundreds of generations, perhaps—acquire a great number -of vocal symbols. These at first would express various -emotions, as of affection, fear, anxiety, sympathy, and so -forth. Other signals would be used to indicate the approach -of enemies, or as battle-cries. I can see no reason why -gradually the use of particular vocal signs to indicate various -objects, animate or inanimate, and various actions, should -not follow after a while. And though the possession and -use of many, even of many hundreds, of such signs would be -very far from even the most imperfect of the languages now -employed by savage races, one can perceive the possibility—which -is all that at present we can expect to recognize—that -out of such systems of vocal signalling a form of language -might arise, which, undergoing slow and gradual development, -should, in the course of many generations, approach -in character the language of the lowest savage races. That -from such a beginning language should attain its higher and -highest developments is not more wonderful in kind, though -much more wonderful, perhaps, in degree, than that from -the first imperfect methods of printing should have arisen -the highest known developments of the typographic art. -The real difficulty lies in conceiving how mere vocal signalling -became developed into what can properly be regarded -as spoken language.</p> - -<p>Of the difficulties related to the origin of, or rather the -development of, man’s moral consciousness, space will not -permit me to speak, even though there were much to be said<span class="pagenum"><a id="Page_329">329</a></span> -beyond the admission that these difficulties have not as yet -been overcome. It must be remembered, however, that -races of men still exist whose moral consciousness can hardly -be regarded as very fully developed. Not only so, but, -through a form of reversion to savage types, the highest -and most cultivated races of man bring forth from time to -time (as our police reports too plainly testify) beings utterly -savage, brutal, and even (“which is else”) bestial. Nay, the -man is fortunate who has never had occasion to control innate -tendencies to evil which are at least strongly significant of -the origin of our race. To most minds it must be pleasanter -as certainly it seems more reasonable, to believe that the -evil tendencies of our race are manifestations of qualities -undergoing gradual extinction, than to regard them as the -consequences of one past offence, and so to have no reason -for trusting in their gradual eradication hereafter. But, as -Darwin says, in the true scientific spirit, “We are not here -concerned with hopes or fears, only with the truth as far as -our reason allows us to discover it. We must acknowledge -that man, with all his noble qualities, with sympathy which -feels for the most debased, with benevolence which extends -not only to other men but to the humblest living creature, -with his God-like intellect which has penetrated into the -movements and constitution of the solar system,—with all -these exalted powers, man still bears in his bodily frame the -indelible stamp of his lowly origin.” As it seems to me, -man’s moral nature teaches the same lesson with equal, if -not greater, significance.</p> - -<hr /> - -<p><span class="pagenum"><a id="Page_330">330</a></span></p> - -<div class="chapter"> -<h2><a id="THE_USE_AND_ABUSE_OF_FOOD"></a><i>THE USE AND ABUSE OF FOOD.</i></h2> -</div> - -<p class="in0">Francis Bacon has laid it down as an axiom that experiment -is the foundation of all real progress in knowledge. “Man,” -he said, “as the minister and interpreter of nature, does and -understands as much as his observations on the order of -nature permit him, and neither knows nor is capable of -more.”<a id="FNanchor_41" href="#Footnote_41" class="fnanchor">41</a> It would seem, then, as if there could be no -subject on which man should be better informed than on the -value of various articles of food, and the quantity in which -each should be used. On most branches of experimental -inquiry, a few men in each age—perhaps but for a few ages -in succession—have pursued for a longer or shorter portion -of their life, a system of experiment and observation. But -on the subject of food or diet all men in all ages have been -practical experimenters, and not for a few years only, but -during their entire life. One would expect, then, that no -questions could be more decisively settled than those which -relate to the use or the abuse of food. Every one ought to -know, it might be supposed, what kinds of food are good for -the health, in what quantity each should be taken, what -changes of diet tend to correct this or that kind of ill-health, -and how long each change should be continued.</p> - -<p>Unfortunately, as we know, this is far from being the -case. We all eat many things which are bad for us, and -omit to eat many things which would be good for us. We<span class="pagenum"><a id="Page_331">331</a></span> -change our diet, too often, without any consideration, or -from false considerations, of the wants of the body. When -we have derived benefit from some change of diet, we are -apt to continue the new diet after the necessity for it has -passed away. As to quantity, also, we seldom follow well-judged -rules. Some take less nutriment (or less of some -particular form of nutriment) than is needed to supply the -absolute requirements of the system; others persistently -overload the system, despite all the warnings which their -own experience and that of others should afford of the mischief -likely to follow that course.</p> - -<p>It is only of late years that systematic efforts have been -made to throw light on the subject of the proper use of food, -to distinguish between its various forms, and to analyze the -special office of each form. I propose to exhibit, in a -popular manner, some of the more important practical conclusions -to which men of science have been led by their -investigations into these questions.</p> - -<p>The human body has been compared to a lamp in which -a flame is burning. In some respects the comparison is a -most apt one, as we shall see presently. But man does -more than <em>live</em>; he <em>works</em>,—with his brain or with his -muscles. And therefore the human frame may be more -justly compared to a steam-engine than to the flame of a -lamp. Of mere life, the latter illustration is sufficiently apt, -but it leaves unillustrated man’s capacity for work; and -since food is taken with two principal objects—the maintenance -of life and the renewal of material used up in brain -work and muscular work—we shall find that the comparison -of man to a machine affords a far better illustration of our -subject than the more common comparisons of the life of man -to a burning flame, and of food to the fuel which serves to -maintain combustion.</p> - -<p>There is, however, one class of food, and, perhaps, on -the whole, the most important, the operation of which is -equally well illustrated by either comparison. The sort of -food to which I refer may be termed <em>heat-maintaining</em> food.<span class="pagenum"><a id="Page_332">332</a></span> -I distinguish it thus from food which serves other ends, but -of course it is not to be understood that any article of diet -serves <em>solely</em> the end of maintaining heat. Accordingly, we -find that heat-maintaining substance exists in nearly all the -ordinary articles of food. Of these there are two—sugar -and fat—which may be looked on as special “heat-givers.” -Starch, also, which appears in all vegetables, and thus comes -to form a large proportion of our daily food, is a heat-giver. -In fact, this substance only enters the system in the form of -sugar, the saliva having the power of converting starch -(which is insoluble in water) into sugar, and thus rendering -it soluble and digestible.</p> - -<p>Starch, as I have said, appears in all vegetables. But it -is found more freely in some than in others. It constitutes -nearly the whole substance of arrowroot, sago, and tapioca, -and appears more or less freely in potatoes, rice, wheat, -barley, and oats. In the process of vegetation it is converted -into sugar; and thus it happens that vegetable diet—whether -presenting starch in its natural form to be converted into -sugar by the consumer, or containing sugar which has -resulted from a process of change undergone by starch—is -in general heat-maintaining. Sugar is used as a convenient -means of maintaining the heat-supply; for in eating sugar -we are saved the trouble of converting starch into sugar. A -love for sweet things is the instinctive expression of the -necessity for heat-maintaining food. We see this liking -strongly developed in children, whose rapid growth is continually -drawing upon their heat-supply. So far as adults -are concerned, the taste for sweet food is found to prevail -more in temperate than in tropical climes, as might be -expected; but, contrary to what we might at first expect, -we do not find any increase in the liking for sweet food in -very cold climates. Another and a more effective way of -securing the required heat-supply prevails in such countries.</p> - -<p>As starch is converted into sugar, so by a further process -sugar is converted into fat. It is by the conversion of sugar -into fat that its heat-supplying power is made available.<span class="pagenum"><a id="Page_333">333</a></span> -This conversion takes place in the vegetable as well as in -the animal system, and thus fat appears in a variety of forms—as -butter, suet, oil, and so forth. Now, precisely as sugar -is a more convenient heat-supplier than starch, so fat -exceeds sugar in its power of maintaining animal heat. It -has been calculated that one pound of fat—whether in the -form of suet, butter, or oil—will go as far towards the -maintenance of animal heat as two pounds of sugar, or as -two pounds and a half of starch. Thus it happens that in -very cold countries there is developed a taste for such -articles of food as contain most fat, or even for pure fat and -its analogues—oil, butter, tallow, dripping, and other forms -of <em>grease</em>.</p> - -<p>I have spoken of starch, sugar, and fat as heat-forming -articles of food; but I must note their influence in the -development of muscles and nerves. Without a certain -proportion of fat in the food a wasting of the tissues will -always take place; for muscles and nerves cannot form -without fat. And conversely, the best remedy for wasting -diseases is to be found in the supply of some easily digestible -form of fatty food. Well-fatted meat, and especially meat in -which the fat is to be seen distributed through the flesh, may -be taken under such circumstances. Butter and salad oil -are then also proper articles of food. Cream is still better, -and cream cheeses may be used with advantage. It is on -account of its heat-supplying and fat-forming qualities that -cod-liver oil has taken its place as one of the most valuable -remedies for scrofulous and consumptive patients.</p> - -<p>But it must be noted that the formation of fat is not the -object with which heat-supplying food is taken. It is an -indication of derangement of the system when heat-giving -food is too readily converted into fat. And in so far as this -process of conversion takes place beyond what is required -for the formation of muscles and nerves, the body suffers in -the loss of its just proportion of heat-supply. Of course, if -too large an amount of heat-giving food is taken into the -system, we may expect that the surplus will be deposited in<span class="pagenum"><a id="Page_334">334</a></span> -the form of adipose tissue. The deposition of fat in such a -case will be far less injurious to the system than an excessive -heat-supply would be. But when only a just amount of -heat-giving food is taken, and in place of fulfilling its just -office this food is converted into adipose tissue, it becomes -necessary to inquire into the cause of the mischief. -Technically, the evil may be described as resulting from the -deficient oxygenation of the heat-supplying food. This -generally arises from defective circulation, and may often be -cured by a very moderate but <em>systematic</em> increase in the -amount of daily exercise, or by the use of the sponge-bath, -or, lastly, by such changes in the dress—and especially in -the articles of attire worn next to the skin—as tend to -encourage a freer circulation of the blood. The tendency -to accumulate fat may sometimes be traced to the use of -over-warm coverings at night, and especially to the use of -woollen night-clothes. By attending to considerations of -this sort, more readily and safely than by an undue diminution -of the amount of heat-supplying food, the tendency to -obesity may frequently be corrected.</p> - -<p>In warm weather we should diminish the supply of heat-giving -food. In such weather the system does not require -the same daily addition to its animal heat, and the excess is -converted into fat. Experiments have shown that despite the -increased rate at which perspiration proceeds during the -summer months, men uniformly fed throughout the year increase -in weight in summer and lose weight in winter.</p> - -<p>So far as mere existence is concerned, heat-forming food -may be looked upon as the real fuel on which the lamp of -life is sustained. But man, considered as a working being, -cannot exist without <em>energy-forming</em> food. All work, whether -of the brain or of the limbs, involves the exhaustion of -nervous and muscular matter; and unless the exhausted -matter be renewed, the work must come to an end. The -supply of heat-giving food may be compared to the supply -of fuel for the fire of a steam-engine. By means of this -supply the <em>fire</em> is kept alive; but if the fire have nothing to<span class="pagenum"><a id="Page_335">335</a></span> -work upon, its energies are wasted or used to the injury of -the machine itself. The supply of water, and its continual -use (in the form of steam) in the propulsion of the engine, -are the processes corresponding to the continual exhaustion -and renewal of the muscles and nerves of the human frame. -And the comparison may be carried yet further. We see -that in the case of the engine the amount of smoke, or -rather of carbonic acid, thrown out by the blast-pipe is a -measure of the vital energy (so to speak) within the engine; -but the amount of work done by the engine is measured -rather by the quantity of steam which is thrown out, because -the elastic force of every particle of steam has been exerted -in the propulsion of the engine before being thrown out -through the blast-pipe. In a manner precisely corresponding -to this, the amount of carbonic acid gas exhaled by a -man is a measure of the rate at which mere existence is proceeding; -but the amount of work, mental or muscular, -which the man achieves, is measured by the amount of used-up -brain-material and muscle-material which is daily thrown -off by the body. I shall presently show in what way this -amount is estimated.</p> - -<p>In the composition of the muscles there is a material -called <em>fibrine</em>, and in the composition of the nerves there is -a material called <em>albumen</em>. These are the substances<a id="FNanchor_42" href="#Footnote_42" class="fnanchor">42</a> which -are exhausted during mental and bodily labour, and which -have to be renewed if we are to continue working with our -head or with our hands. Nay more, life itself involves -work; the heart, the lungs, the liver, each internal organ of -the body, performs its share of work, just as a certain proportion -of the power of a steam-engine is expended in merely -moving the machinery which sets it in action. If the waste -of material involved in this form of work is not compensated<span class="pagenum"><a id="Page_336">336</a></span> -by a continual and sufficient supply of fibrine and albumen -the result will be a gradual lowering of all the powers of the -system, until some one or other gives way,—the heart ceases -to beat, or the stomach to digest, or the liver to secrete bile,—and -so death ensues.</p> - -<p>The fibrine and albumen in the animal frame are derived -exclusively from vegetables. For although we seem to -derive a portion of the supply from animal food, yet the -fibrine and albumen thus supplied have been derived in the -beginning from the vegetable kingdom. “It is the peculiar -property of the plant,” says Dr. Lankester, “to be able, in -the minute cells of which it is composed, to convert the carbonic -acid and ammonia which it gets from the atmosphere -into fibrine and albumen, and by easy chemical processes -we can separate these substances from our vegetable food. -Wheat, barley, oats, rye, rice, all contain fibrine, and some -of them also albumen. Potatoes, cabbage, and asparagus -contain albumen. It is a well-ascertained fact that those -substances which contain most of these ‘nutritious secretions,’ -as they have been called, support life the longest.” -They change little during the process of digestion, entering -the blood in a pure state, and being directly employed to -renew the nervous and muscular matter which has been -used up during work, either mental or muscular. Thus the -supply of these substances is continually being drawn upon. -The carbon, which forms their principal constituent, is converted -into carbonic acid; and the nitrogen, which forms -about a sixth part of their substance, re-appears in the nitrogen -of urea, a substance which forms the principal solid -constituent of the matter daily thrown from the system -through the action of the kidneys. Thus the amount of -urea which daily passes from the body affords a measure of -the work done during the day. “This is not,” says Dr. -Lankester, “the mere dream of the theorist; it has been -practically demonstrated that increased stress upon the -nervous system, viz., brain work, emotion, or excitement -from disease, increases the quantity of urea and the demand<span class="pagenum"><a id="Page_337">337</a></span> -for nitrogenous food. In the same manner the amount of -urea is the representative of the amount of muscular work -done.”</p> - -<p>It has been calculated that the average amount of urea -daily formed in the body of a healthy man is about 470 -grains. To supply this daily consumption of nitrogenous -matter, it is necessary that about four ounces of flesh-forming -substance should be consumed daily. It is important, -therefore, to inquire how this substance may be obtained. -The requisite quantity of albuminous and fibrinous matter -“is contained,” says Dr. Lankester, “in a pound of beef; in -two pounds of eggs; in two quarts of milk; in a pound of -peas; in five pounds of rice; in sixteen pounds of potatoes; -in two pounds of Indian meal; in a pound and a half of -oatmeal; and in a pound and three-quarters of flour.” A -consideration of this list will show the importance of attending -to the quality as well as the quantity of our food. A -man of ordinary appetite might satisfy his hunger on potatoes -or on rice, without by any means supplying his system with -a sufficient amount of flesh-forming food. On the other -hand, if a man were to live on bread and beef alone, he -would load his system with an amount of nitrogenous food, -although not taking what could be considered an excessive -amount of daily nourishment. We see, also, how it is -possible to continually vary the form in which we take the -required supply of nitrogenous food, without varying the -amount of that supply from day to day.</p> - -<p>The supply itself should of course also vary from day to -day as the amount of daily work may vary. What would be -ample for a person performing a moderate amount of work -would be insufficient for one who underwent daily great -bodily or mental exertions, and would be too much for one -who was taking holiday. It would appear, from the researches -of Dr. Haughton, that the amount of urea daily -formed in the body of a healthy man of average weight varies -from 400 to 630 grains. Of this weight it appears that 300 -grains results from the action of the internal organs. It<span class="pagenum"><a id="Page_338">338</a></span> -would seem, therefore, that the amount of flesh-forming food -indicated in the preceding paragraph may be diminished in -the proportion of 47 to 40 in the case of a person taking the -minimum of exercise—that is, avoiding all movements save -those absolutely necessary for comfort or convenience. On -the other hand, that amount must be increased in the proportion -of 74 to 63 in the case of a person (of average weight) -working up to his full powers. It will be seen at once, -therefore, that a hardworking man, whether labourer or -thinker, must make good flesh-forming food constitute a considerable -portion of his diet; otherwise he would require to -take an amount of food which would seriously interfere with -his comfort and the due action of his digestive organs. For -instance, if he lived on rice alone, he would require to ingest -nearly seven pounds of food daily; if on potatoes, he would -require upwards of twenty-one pounds; whereas one pound -and a third of meat would suffice to supply the same amount -of flesh-forming food.</p> - -<p>Men who have to work, quickly find out what they -require in the way of food. The Irishman who, while doing -little work, will live contentedly on potatoes, asks for better -flesh-forming food when engaged in heavy labour. In fact, -the employer of the working man, so far from feeling aggrieved -when his men require an improvement in their diet, -either as respects quality or quantity, ought to look on the -want as evidence that they are really working hard in his -service, and also that they have a capacity for continuous -work. The man who lives on less than the average share of -flesh-forming food is doing less than an average amount of -work; the man who is unable to eat an average quantity -of flesh-forming food, is <em>unable</em> to do an average amount of -work. “‘On what principle do you discharge your men?’ -I once said,” relates Dr. Lankester, “to a railway contractor. -‘Oh,’ he said, ‘it’s according to their appetites.’ ‘But,’ I -said, ‘how do you judge of that?’ ‘Why,’ he said, ‘I send a -clerk round when they are getting their dinners, and those -who can’t eat he marks with a bit of chalk, and we send -them about their business.’”</p> - -<p><span class="pagenum"><a id="Page_339">339</a></span> -At a lecture delivered at the Royal Museum of Physics -and Natural History at Florence, by Professor Mantegazza, -a few years since, the Professor dwelt on the insufficient food -which Italians are in the habit of taking, as among the most -important causes of the weakness of the nation. “Italians,” -he said, “you should follow as closely as you can the -example of the English in your eating and in your drinking, -in the choice of flesh-meat (in tossing off bumpers of your -rich wines),<a id="FNanchor_43" href="#Footnote_43" class="fnanchor">43</a> in the quality of your coffee, your tea, and your -tobacco. I give you this advice, dear countrymen, not only -as a medical man, but also as a patriot. It is quite evident, -from the way millions of you perform the process which you -call eating and drinking, that you have not the most elementary -notions of the laws of physiology. You imagine -that you are living. You are barely prolonging existence on -maccaroni and water-melons. You neither know how to eat -nor how to drink. You have no muscular energy; and, -therefore, you have no continuous mental energy. The -weakness of the individual, multiplied many millions of times, -results in the collective weakness of the nation. Hence results -insufficient work, and thence insufficient production. Thus -the returns of the tax-collector and the custom-house officer -are scanty, and the national exchequer suffers accordingly.” -Nor is all this, strange as it may sound, the mere gossip of -the lecture-room. “The question of good feeding,” says -Dr. Lankester, “is one of national importance. It is vain -to expect either brain or muscles to do efficient work when -they are not provided with the proper material. Neither -intellectual nor physical work can be done without good -food.”</p> - -<p>We have now considered the two principal forms of -food, the heat-forming—sometimes called the <em>amylaceous</em>—constituents, -and the flesh-forming or <em>nitrogenous</em> constituents. -But there are other substances which, although forming a -smaller proportion of the daily food, are yet scarcely less<span class="pagenum"><a id="Page_340">340</a></span> -important. Returning to our comparison of the human -system to a steam-engine—we have seen how the heat-forming -and flesh-forming constituents of food correspond to the -supply of fuel and water; but an engine would quickly fall -into a useless state if the wear and tear of the material of -which it is constructed were not attended to and repaired. -Now, in the human frame there are materials which are continually -being used up, and which require to be continually -restored, if the system is to continue free from disease. -These materials are the mineral constituents of the system. -Amongst them we must include <em>water</em>, which composes a -much larger portion of our bodies than might be supposed. -Seven-ninths of our weight consists simply of water. Every -day there is a loss of about one-thirtieth part of this constituent -of our system. The daily repair of this important -waste of material is not effected by imbibing a corresponding -supply of water. A large proportion of the weight of water -daily lost is renewed in the solid food. Many vegetables -consist principally of water. This is notably the case with -potatoes. Where the water supplied to a district is bad, so -that little water is consumed by the inhabitants—at least, -without the addition of some other substance—it becomes -important to notice the varying proportion of water present -in different articles of food. As an instance of this, I may -call attention to a remarkable circumstance observed during -the failure of the potato crops in Ireland. Notwithstanding -the great losses which the people sustained at that time, it -was noticed that the amount of tea imported into Ireland -exhibited a remarkable increase. This seemed at first sight -a somewhat perplexing phenomenon. The explanation was -recognized in the circumstance that the potato—a watery -vegetable, as we have said—no longer formed the chief -portion of the people’s diet. Thus the deficiency in the -supply of water had to be made up by the use of a larger -quantity of fluid food; and as simple water was not palatable -to the people, they drank tea in much larger quantities than -they had been in the habit of taking before the famine.</p> - -<p><span class="pagenum"><a id="Page_341">341</a></span> -But we have to consider the other mineral constituents of -the system.</p> - -<p>If I were to run through the list of all the minerals which -exist within the body, I should weary the patience of the -reader, and perhaps not add very much to the clearness of -his ideas respecting the constitution of the human frame. -Let it suffice to state generally that, according to the calculations -of physiologists, a human body weighing 154 pounds -contains about 17½ pounds of mineral matter; and that the -most important mineral compounds existing within the body -are those which contain lime, soda, and potash. Without -pretending to any strictly scientific accuracy in the classification, -we may say that the lime is principally found in the -bones, the soda in the blood, the potash in the muscles; and -according as one or other of these important constituents is -wanting in our food, so will the corresponding portions of the -frame be found to suffer.</p> - -<p>We have a familiar illustration of the effects of unduly -diminishing the supply of the mineral constituents of the -body in the ravages which scurvy has worked amongst the -crews of ships which have remained for a long period ill-supplied -with fresh vegetables. Here it is chiefly the want -of potash in the food which causes the mischief. An interesting -instance of the rapid—almost startling—effects of food -containing potash, in the cure of men stricken by scurvy, -is related by Dana. The crew of a ship which had been -several months at sea, but was now nearing the land, were -prostrated by the ravages of scurvy. Nearly all seemed hopelessly -ill. One young lad was apparently dying, the livid -spots which were spreading over his limbs seeming to betoken -his rapidly approaching end. At this moment a ship appeared -in view which had but lately left the land, and was -laden with fresh vegetables. Before long large quantities of -the life-bearing food had been transferred to the decks of the -other ship. The instincts of life taught the poor scurvy-stricken -wretches to choose the vegetable which of all others -was best suited to supply the want under which their frames<span class="pagenum"><a id="Page_342">342</a></span> -were wasting. They also were led by the same truthful -instincts to prefer the raw to cooked vegetables. Thus the -sick were to be seen eating raw onions with a greater relish -than the gourmand shows for the most appetising viands. -But the poor lad who was the worse of the sufferers had -already lost the power of eating; and it was without a hope -of saving his life that some of his companions squeezed the -juice of onions between his lips, already quivering with the -tremor of approaching death. He swallowed a few drops, -and presently asked for more. Shortly he began to revive, -and to the amazement of all those who had seen the state of -prostration to which he had been reduced, he regained in a -few days his usual health and strength.</p> - -<p>The elements which we require in order to supply the -daily waste of the mineral constituents of the body are contained -in greater or less quantities in nearly all the articles -which man uses for food. But it may readily happen that, -by adopting an ill-regulated diet, a man may not take a -sufficient quantity of these important elements. It must -also be noticed that articles of food, both animal and -vegetable, may be deprived of a large proportion of their -mineral elements by boiling; and if, as often happens, the -water in which the food has been boiled is thrown away, -injurious effects can scarcely fail to result from the free use -of food which has lost so important a portion of its constituent -elements. Accordingly, when persons partake much -of boiled meat, they should either consume the broth with -the meat, or use it as soup on the alternate days. Vegetables -steamed in small quantities of water (this water being taken -with them), also afford a valuable addition to boiled meat. -In fact, experience seems to have suggested the advantage -of mixing carrots, parsnips, turnips, and greens with boiled -meat; but unfortunately the addition is not always made in -a proper manner. If the vegetables are boiled separately -in large quantities of water, and served up after this water -has been thrown away, more harm than good is done by the -addition; since the appetite is satisfied with comparatively<span class="pagenum"><a id="Page_343">343</a></span> -useless food, instead of being left free to choose, as it might -otherwise do, such forms of food as would best supply the -requirements of the system. Salads and uncooked fruits, -for instance, contain saline ingredients in large proportion, -and could be used advantageously after a meal of boiled -meat. Potatoes are likewise a valuable article of food on -account of the mineral elements contained in them. And -there can be no doubt that the value of potatoes as an article -of food is largely increased when they are cooked in their -skins, after the Irish fashion.</p> - -<p>Lastly, we must consider those articles of food which -promote the natural vital changes, but do not themselves -come to form part of the frame, or, at least, not in any large -proportion of their bulk. Such are tea, coffee, and cocoa: -alchoholic drinks; narcotics; and lastly, spices and condiments. -We may compare the use of these articles of food -to that of oil in lubricating various parts of a steam-engine. -For, as the oil neither forms part of the heat-supply nor of -the force-supply of the steam-engine, nor is used to replace -the worn material of its structure, yet serves to render the -movements of the machine more equable and effective, so -the forms of food we are considering are neither heat-producing -nor flesh-forming, nor do they serve to replace, to -any great extent, the mineral constituents of the body, yet -they produce a sense of refreshment accompanied with renewed -vigour. It is difficult to determine in what precise -way these effects are produced, but no doubt can exist as to -the fact that they are really attributable to the forms of food -to which we have assigned them.</p> - -<p>Tea, coffee, and cocoa owe their influence on the nervous -system to the presence of a substance which has received the -various names of <em>theine</em>, <em>caffeine</em>, and <em>theobromine</em>. It is -identical in composition with <em>piperine</em>, the most important -ingredient in pepper. It may be separated in the form of -delicate white, silky crystals, which have a bitter taste. In -its concentrated form this substance is poisonous, and to -this circumstance must be ascribed the ill effects which follow<span class="pagenum"><a id="Page_344">344</a></span> -from the too free use of strong tea or coffee. However, the -instances of bad effects resulting from the use of “the cup -which cheers but not inebriates” are few and far between, -while the benefits derived from it are recognized by all. -It has, indeed, been stated that no nation which has begun -to make use of tea, coffee, or cocoa, has ever given up the -practice; and no stronger evidence can be required of the -value of those articles of food.</p> - -<p>Of alcoholic liquors it is impossible to speak so favourably. -They are made use of, indeed, almost as extensively -as tea or coffee; they have been made the theme of the -poet, and hailed as the emblems of all that is genial and -convivial. Yet there can be little doubt that, when a -balance is struck between the good and evil which have -resulted to man from their use, the latter is found largely to -preponderate. The consideration of these evils belongs, -however, rather to the moralist than to the physiologist. I -have here simply to consider alcoholic liquors as articles of -food. There can be little doubt that, when used with -caution and judgment, they afford in certain cases an important -adjunct to those articles which are directly applied -to the reparation of bodily waste. Without absolutely -nourishing the frame, they ultimately lead to this end by -encouraging the digestive processes which result in the -assimilation of nutritive articles of food. But the quantity -of alcohol necessary to effect this is far less than is usually -taken even by persons who are termed temperate. It is -also certain that hundreds make use of alcoholic liquors -who have no necessity for them, and who would be better -without them. Those who require them most are men who -lead a studious sedentary life; and it is such men, also, -who suffer most from excess in the use of alcoholic liquors.</p> - -<p>It remains that I should make a few remarks on mistakes -respecting the quantity of food.</p> - -<p>Some persons fall into the habit of taking an excessive -quantity of food, not from greediness, but from the idea -that a large amount of food is necessary for the maintenance<span class="pagenum"><a id="Page_345">345</a></span> -of their strength. They thus overtax the digestive organs, -and not only fail of their purpose, but weaken instead of -strengthening the system. Especially serious is the mistake -often made by persons in delicate health of swallowing—no -other word can be used, for the digestive organs altogether -refuse to respond to the action of the mouth—large -quantities of some concentrated form of food, such as even -the strongest stomach could not deal with in that form. I -knew a person who, though suffering from weakness such -as should have suggested the blandest and simplest forms -of food, adopted as a suitable breakfast mutton-chops and -bottled stout, arguing, when remonstrated with, that he required -more support than persons in stronger health. He -was simply requiring his weak digestive organs to accomplish -work which would have taxed the digestive energies -of the most stalwart labourer working daily in the open air -for many hours.</p> - -<p>On the other hand, a too abstemious diet is as erroneous -in principle as a diet in excess of the natural requirements -of the system. A diet which is simply too abstemious is -perhaps less dangerous than persistent abstinence from the -use of certain necessary forms of food. Nature generally -prevents us from injuring ourselves by unwisely diminishing -the quantity of food we take; but unfortunately she -is not always equally decided in her admonitions respecting -the quality of our food. A man may be injuring -his health through a deficiency in the amount either of the -heat-forming or of the flesh-forming food which he consumes, -and yet know nothing of the origin of the mischief. It may -also be noted that systematic abstinence, either as respects -quantity or quality of food, is much more dangerous than -an occasional fast. Indeed, it is not generally injurious -either to abstain for several days from particular articles or -forms of food, or to remain, for several hours beyond the -usual interval between meals, without food of any sort. On -the contrary, benefit often arises from each practice. The -Emperor Aurelian used to attribute the good health he<span class="pagenum"><a id="Page_346">346</a></span> -enjoyed to his habit of abstaining for a whole day, once a -month, from food of all sorts; and many have found the -Lenten rules of abstinence beneficial. As a rule, however, -change of diet is a safer measure than periodical fasting or -abstinence from either heat-producing or flesh-forming food. -It must be noticed, in conclusion, that young persons ought -not, without medical advice, to fast or abstain for any length -of time from the more important forms of food, as serious -mischief to the digestive organs frequently follows from -either course.</p> - -<hr /> - -<p><span class="pagenum"><a id="Page_347">347</a></span></p> - -<div class="chapter"> -<h2><a id="OZONE"></a><i>OZONE.</i></h2> -</div> - -<p class="in0">The singular gas termed ozone has attracted a large amount -of attention from chemists and meteorologists. The vague -ideas which were formed as to its nature when as yet it had -been but newly discovered, have given place gradually to -more definite views; and though we cannot be said to have -thoroughly mastered all the difficulties which this strange -element presents, yet we know already much that is interesting -and instructive.</p> - -<p>Let us briefly consider the history of ozone.</p> - -<p>Nine years after Priestley had discovered oxygen, Van -Marum, the electrician, noticed that when electric sparks -are taken through that gas, a peculiar odour is evolved. -Most people know this odour, since it is always to be -recognized in the neighbourhood of an electrical machine -in action. In reality, it indicates the presence of ozone in -the air. But for more than half a century after Van Marum -had noticed it, it was supposed to be the “smell of electricity.”</p> - -<p>In 1840, Schönbein began to inquire into the cause of -this peculiar odour. He presently found that it is due to -some change in the oxygen; and that it can be produced -in many ways. Of these, the simplest, and, in some respects, -the most interesting, is the following:—“Take sticks of -common phosphorus, scrape them until they have a metallic -lustre, place them in this condition under a large bell-jar, -and half-cover them with water. The air in the bell-jar is<span class="pagenum"><a id="Page_348">348</a></span> -soon charged with ozone, and a large room can readily be -supplied with ozonized air by this process.”</p> - -<p>Schönbein set himself to inquire into the properties of -this new gas, and very interesting results rewarded his researches. -It became quite clear, to begin with, that whatever -ozone may be, its properties are perfectly distinct from -those of oxygen. Its power of oxidizing or rusting metals, -for example, is much greater than that which oxygen possesses. -Many metals which oxygen will not oxidize at all, -even when they are at a high temperature, submit at once -to the influence of ozone. But the power of ozone on other -substances than metals is equally remarkable. Dr. Richardson -states that, when air is so ozonized as to be only -respirable for a short time, its destructive power is such that -gutta-percha and india-rubber tubings are destroyed by -merely conveying it.</p> - -<p>The bleaching and disinfecting powers of ozone are very -striking. Schönbein was at first led to associate them with -the qualities of chlorine gas; but he soon found that they -are perfectly distinct.</p> - -<p>It had not yet been shown whether ozone was a simple -or a compound gas. If simple, of course it could be but -another form of oxygen. At first, however, the chances -seemed against this view; and there were not wanting skilful -chemists who asserted that ozone was a compound of -the oxygen of the air with the hydrogen which forms an -element of the aqueous vapour nearly always present in the -atmosphere.</p> - -<p>It was important to set this question at rest. This was -accomplished by the labours of De la Rive and Marignac, -who proved that ozone is simply another form of oxygen.</p> - -<p>Here we touch on a difficult branch of modern chemical -research. The chemical elements being recognized as the -simplest forms of matter, it might be supposed that each -element would be unchangeable in its nature. That a compound -should admit of change, is of course a thing to be -expected. If we decompose water, for instance, into its<span class="pagenum"><a id="Page_349">349</a></span> -component elements, oxygen and hydrogen, we may look -on these gases as exhibiting water to us in another form. -And a hundred instances of the sort might be adduced, in -which, either by separating the elements of a compound, or -by re-arranging them, we obtain new forms of matter without -any real change of substance. But with an element, -the case, one would suppose, should be different.</p> - -<p>However, the physicist must take facts as he finds them; -and amongst the most thoroughly recognized chemical facts -we have this one, that elementary substances may assume -different forms. Chemists call the phenomenon allotropy. -A well-known instance of allotropy is seen in red phosphorus. -Phosphorus is one of the chemical elements; and, -as every one knows, the form in which it is usually obtained -is that of a soft, yellow, semi-transparent solid, somewhat -resembling bees’ wax in consistence, poisonous, and readily -taking fire. Red phosphorus is the same element, yet differs -wholly in its properties. It is a powder, it does not readily -take fire, and it is not poisonous.</p> - -<p>Ozone, then, is another form of oxygen. It is the only -instance yet discovered of gaseous allotropy.</p> - -<p>And now we have to deal with the difficult and still-vexed -questions of the way in which the change from oxygen -is brought about, and the actual distinction between the -two forms of the same gas. Schönbein held that common -oxygen is produced by the combination of two special forms -of oxygen—the positive and the negative, or, as he called -them, ozone and antozone. He showed that, in certain -conditions of the air, the atmospheric oxygen exhibits qualities -which are the direct reverse of those which ozone -exhibits, and are distinct from those of ordinary oxygen. -In oxygen thus negatived or antozonized, animals cannot -live any more than they can in nitrogen. The products of -decomposition are not only not destroyed as by ozone, but -seem subject to preservative influences, and speedily become -singularly offensive; dead animal matter rapidly putrefies, -and wounds show a tendency to mortification.</p> - -<p><span class="pagenum"><a id="Page_350">350</a></span> -But the theory of positive and negative forms of oxygen, -though still held by a few physicists, has gradually given -way before the advance of new and sounder modes of inquiry. -It has been proved, in the first place, that ozone is -denser than ordinary oxygen. The production of ozone is -always followed by a contraction of the gas’s volume, the -contraction being greater or less according to the amount of -oxygen which has been ozonized. Regularly as the observers—Messrs. -Andrews and Tait—converted a definite -proportion of oxygen into ozone, the corresponding contraction -followed, and as regularly was the original volume -of the gas restored when, by the action of heat, the ozone -was reconverted into oxygen.</p> - -<p>And now a very singular experiment was made by the -observers, with results which proved utterly perplexing to -them. Mercury has the power of absorbing ozone; and -the experimenters thought that if, after producing a definite -contraction by the formation of ozone, they could absorb -the ozone by means of mercury, the quantity of oxygen -which remained would serve to show them how much ozone -had been formed, and thence, of course, they could determine -the density of ozone.</p> - -<p>Suppose, for instance, that we have one hundred cubic -inches of oxygen, and that by any process we reduce it to -a combination of oxygen and ozone occupying ninety-five -cubic inches. Now, if the mercury absorbed the ozone, -and we found, say, that there only remained eighty-five -cubic inches of oxygen, we could reason in this way:—Ten -cubic inches were occupied by the ozone before the mercury -absorbed it; but these correspond to fifteen cubic inches -of oxygen; hence, ozone must be denser than oxygen in -the proportion of fifteen to ten, or three to two. And whatever -result might have followed, a real absorption of the -ozone by the mercury would have satisfactorily solved the -problem.</p> - -<p>But the result actually obtained did not admit of interpretation -in this way. The apparent absorption of the<span class="pagenum"><a id="Page_351">351</a></span> -ozone by the mercury, that is, the disappearance of the -ozone from the mixture, was accompanied by <em>no diminution -of volume at all</em>. In other words, returning to our illustrative -case, after the absorption of the ozone from the ninety-five -cubic inches occupied by the mixture, there still remained -ninety-five cubic inches of oxygen; so that it seemed as -though an evanescent volume of ozone corresponded in -weight to five cubic inches of oxygen. This solution, of -course, could not be admitted, since it made the density of -ozone <em>infinite</em>.</p> - -<p>The explanation of this perplexing experiment is full of -interest and instruction. The following is the account given -by Mr. C. W. Heaton (Professor of Chemistry at Charing -Cross Hospital), slightly modified, however, so that it may -be more readily understood.</p> - -<p>Modern chemists adopt, as a convenient mode of representing -the phenomena which gases exhibit, the theory that -every gas, whether elementary or compound, consists of -minute molecules. They suppose that these molecules are -of equal size, and are separated by equal intervals so long as -the gas remains unchanged in heat and density. This view -serves to account for the features of resemblance presented -by all gases. The features in which gases vary are accounted -for by the theory that the molecules are differently -constituted. The molecules are supposed to be clusters of -atoms, and the qualities of a gas are assumed to depend on -the nature and arrangement of these ultimate atoms. The -molecules of some elements consist but of a single atom; -the molecules of others are formed by pairs of atoms; those -of others by triplets; and so on. Again, the molecules of -compound gases are supposed to consist of combinations -of different <em>kinds</em> of atoms.</p> - -<p>Now, Dr. Odling, to whom we owe the solution of the -perplexing problem described above, thus interpreted the -observed phenomena. A molecule of oxygen contains two -atoms, one of ozone contains three, <em>and the oxidizing power -of ozone depends on the ease with which it parts with its third<span class="pagenum"><a id="Page_352">352</a></span> -atom of oxygen</em>. Thus, in the experiment which perplexed -Messrs. Andrews and Tait, the mercury only <em>seemed</em> to -absorb the ozone; in reality it converted the ozone into -oxygen by removing its third atom. And now we see how -to interpret such a result as we considered in our illustrative -case. Five cubic inches of oxygen gave up their atoms, -each atom combining with one of the remaining oxygen -doublets, so as to form a set of ozone triplets. Clearly, -then, fifteen cubic inches of oxygen were transformed into -ozone. They now occupied but ten cubic inches; so that -the mixture, or ozonized oxygen, contained eighty-five cubic -inches of oxygen and ten of ozone. When the mercury was -introduced, it simply transformed all the ozone triplets into -oxygen doublets, by taking away the odd atom from each. -It thus left ten cubic inches of oxygen, which, with the remaining -eighty-five, constituted the ninety-five cubic inches -observed to remain after the supposed absorption of the -ozone.</p> - -<p>It follows, of course, that ozone is half as heavy again as -oxygen.</p> - -<p>But, as Mr. Heaton remarked, “this beautiful hypothesis, -although accounting perfectly for all known facts, was -yet but a probability. One link was lacking in the chain of -evidence, and that link M. Soret has supplied by a happily -devised experiment.” Although mercury and most substances -are only capable of converting ozone into oxygen, -oil of turpentine has the power of absorbing ozone in its -entirety. Thus, when the experiment was repeated, with oil -of turpentine in place of the mercury, the ozone was -absorbed, and the remaining oxygen, instead of occupying -ninety-five inches, occupied but eighty-five. After this, no -doubt could remain that Dr. Odling’s ingeniously conceived -hypothesis was the correct explanation of Messrs. Andrews -and Tait’s experiment.</p> - -<p>We recognize, then, in ozone a sort of concentrated -oxygen, with this peculiar property, that it possesses an extraordinary -readiness to part with its characteristic third<span class="pagenum"><a id="Page_353">353</a></span> -atom, and so disappear <em>as ozone</em>, two-thirds of its weight -remaining as oxygen.</p> - -<p>It is to this peculiarity that ozone owes the properties -which render it so important to our welfare. We are indeed, -as yet, in no position to theorize respecting this element, -our knowledge of its very existence being so recent, and our -information respecting its presence in our atmosphere being -of still more recent acquisition.</p> - -<p>Indeed, it is well remarked by Mr. Heaton, that we -had, until quite lately, no reason for confidently adopting -Schönbein’s view that ozone exists in our atmosphere. The -test-papers which Schönbein made use of turned blue under -the influence of ozone, it is true, but they were similarly influenced -by other elements which are known to exist in our -atmosphere, and even the sun’s rays turned them blue. -However, Dr. Andrews has shown how the character of the -air producing the change can be further tested, so as to -render it certain that ozone only has been at work. If -air which colours the test-papers be found to lose the property -after being heated, the change can only be due to -ozone, because nitrous and nitric acids (which have the -power of colouring the test-papers) would not be removed by -the heat, whereas ozone is changed by heat into oxygen.</p> - -<p>Once we are certain that ozone exists in the air, we -must recognize the fact that its presence cannot fail to have -an important bearing on our health and comfort; for ozone -is an exceedingly active agent, and cannot exist anywhere -without setting busily to its own proper work. What that -work is, and whether it is beneficial or deleterious to ourselves, -remains to be considered.</p> - -<p>In the first place, ozone has immense power as a disinfectant. -It decomposes the products emanating from putrefying -matter more effectually than any other known element. -Perhaps the most striking proof ever given of its qualities in -this respect is that afforded by an experiment conducted by -Dr. Richardson a few years ago.</p> - -<p>He placed a pint of blood taken from an ox in a large<span class="pagenum"><a id="Page_354">354</a></span> -wide-mouthed bottle. The blood had then coagulated, and -it was left exposed to the air until it had become entirely -redissolved by the effects of decomposition. At the end of -a year the blood was put into a stoppered bottle, and set -aside for seven years. “The bottle was then taken from its -hiding-place,” says Dr. Richardson, “and an ounce of the -blood was withdrawn. The fluid was so offensive as to produce -nausea when the gases evolved from it were inhaled. -It was subjected by Dr. Wood and myself to a current of -ozone. For a few minutes the odour of ozone was destroyed -by the odour of the gases from the blood; gradually the -offensive smell passed away; then the fluid mass became -quite sweet, and at last a faint odour of ozone was detected, -whereupon the current was stopped. The blood was thus -entirely deodorized; but another and most singular phenomenon -was observed. The dead blood coagulated as the -products of decomposition were removed, and this so perfectly, -that from the new clot that was formed serum exuded. -Before the experiment commenced, I had predicted on -theoretical grounds that secondary coagulation would follow -on purification; and this experiment, as well as several -others afterwards performed, verified the truth of the prediction.”</p> - -<p>It will of course be understood that ozone, in thus acting -as a disinfectant, is transformed into oxygen. It parts with -its third atom as in the mercury experiment, and so loses -its distinctive peculiarity. Thus we might be led to anticipate -the results which come next to be considered.</p> - -<p>Ozone has certain work to do, and in doing that work -is transmuted into oxygen. It follows, then, that where -there has been much work for ozone to do, there we shall -find little ozone left in the air. Hence, in open spaces where -there is little decomposing matter, we should expect to find -more ozone than in towns or cities. This accords with what -is actually observed. And not only is it found that country -air contains more ozone than town air, but it is found that -air which has come from the sea has more ozone than even<span class="pagenum"><a id="Page_355">355</a></span> -the country air, while air in the crowded parts of large cities -has no ozone at all, nor has the air of inhabited rooms.</p> - -<p>So far as we have gone, we might be disposed to speak -unhesitatingly in favour of the effects produced by ozone. -We see it purifying the air which would otherwise be loaded -by the products of decomposing matter, we find it present in -the sea air and the country air which we know to be so -bracing and health-restoring after a long residence in town, -and we find it absent just in those places which we look -upon as most unhealthy.</p> - -<p>Again, we find further evidence of the good effects of -ozone in the fact that cholera and other epidemics never -make their dreaded appearance in the land when the air is -well supplied with ozone—or in what the meteorologists call -“the ozone-periods.” And though we cannot yet explain -the circumstance quite satisfactorily, we yet seem justified -in ascribing to the purifying and disinfecting qualities of -ozone our freedom at those times from epidemics to which -cleanliness and good sanitary regulations are notedly -inimical.</p> - -<p>But there is a reverse side to the picture. And as we -described an experiment illustrating the disinfecting qualities -of ozone before describing the good effects of the element, -we shall describe an experiment illustrating certain less -pleasing qualities of ozone, before discussing the deleterious -influences which it seems capable of exerting.</p> - -<p>Dr. Richardson found that when the air of a room was -so loaded with ozone as to be only respirable with difficulty, -animals placed in the room were affected in a very singular -manner. “In the first place,” he says, “all the symptoms -of nasal catarrh and of irritation of the mucous membranes -of the nose, the mouth, and the throat were rapidly induced. -Then followed free secretion of saliva and profuse action -of the skin—perspiration. The breathing was greatly -quickened, and the action of the heart increased in proportion.” -When the animals were suffered to remain yet -longer within the room, congestion of the lungs followed,<span class="pagenum"><a id="Page_356">356</a></span> -and the disease called by physicians “congestive bronchitis” -was set up.</p> - -<p>A very singular circumstance was noticed also as to the -effects of ozone on the different orders of animals. The -above-mentioned effects, and others which accompanied -them, the description of which would be out of place in -these pages, were developed more freely in carnivorous than -in herbivorous animals. Rats, for example, were much -more easily influenced by ozone than rabbits were.</p> - -<p>The results of Dr. Richardson’s experiments prepare us -to hear that ozone-periods, though characterized by the -absence of certain diseases, bring with them their own forms -of disease. Apoplexy, epilepsy, and other similar diseases -seem peculiarly associated with the ozone-periods, insomuch -that eighty per cent. of the deaths occurring from them take -place on days when ozone is present in the air in larger -quantities than usual. Catarrh, influenza, and affections of -the bronchial tubes, also affect the ozone-periods.</p> - -<p>We see, then, that we have much yet to learn respecting -ozone before we can pronounce definitively whether it is more -to be welcomed or dreaded. We must wait until the researches -which are in progress have been carried out to their -conclusion, and perhaps even then further modes of inquiry -will have to be pursued before we can form a definite -opinion.</p> - -<hr /> - -<p><span class="pagenum"><a id="Page_357">357</a></span></p> - -<div class="chapter"> -<h2><a id="DEW"></a><i>DEW.</i></h2> -</div> - -<p class="in0">There are few phenomena of common occurrence which -have proved more perplexing to philosophers than those -which attend the deposition of dew. Every one is familiar -with these phenomena, and in very early times observant -men had noticed them; yet it is but quite recently that the -true theory of dew has been put forward and established. -This theory affords a striking evidence of the value of careful -and systematic observation applied even to the simplest -phenomena of nature.</p> - -<p>It was observed, in very early times, that dew is only -formed on clear nights, when, therefore, the stars are shining. -It was natural, perhaps, though hardly philosophical, to conclude -that dew is directly shed down upon the earth from -the stars; accordingly, we find the reference of dew to stellar -influences among the earliest theories propounded in explanation -of the phenomenon.</p> - -<p>A theory somewhat less fanciful, but still depending on -supposed stellar influences, was shortly put forward. It -was observed that dew is only formed when the atmosphere -is at a low temperature; or, more correctly, when the air -is at a much lower temperature than has prevailed during -the daytime. Combining this peculiarity with the former -ancient philosophers reasoned in the following manner: -Cold generates dew, and dew appears only when the skies -are clear—that is, when the stars are shining; hence it -follows that the stars generate cold, and thus lead indirectly<span class="pagenum"><a id="Page_358">358</a></span> -to the formation of dew. Hence arose the singular theory, -that as the sun pours down heat upon the earth, so the stars -(and also the moon and planets) pour down cold.</p> - -<p>Nothing is more common—we may note in passing—than -this method of philosophizing, especially in all that -concerns weather-changes; and perhaps it would be impossible -to find a more signal instance of the mistakes into -which men are likely to fall when they adopt this false -method of reasoning; for, so far is it from being true that -the stars shed cold upon the earth, that the exact reverse -is the case. It has been established by astronomers and -physicists that an important portion of the earth’s heat-supply -is derived from the stars.</p> - -<p>Following on these fanciful speculations came Aristotle’s -theory of dew—celebrated as one of the most remarkable -instances of the approximation which may sometimes be -made to the truth by clever reasoning on insufficient observations. -For we must not fall into the mistake of supposing, -as many have done, that Aristotle framed hypotheses -without making observations; indeed, there has seldom -lived a philosopher who has made more observations than -he did. His mistake was that he extended his observations -too widely, not making enough on each subject. He -imagined that, by a string of syllogisms, he could make -a few supply the place of many observations.</p> - -<p>Aristotle added two important facts to our knowledge -respecting dew—namely, first, that dew is only formed in -serene weather; and secondly, that it is not formed on the -summits of mountains. Modern observations show the -more correct statement of the case to be that dew is -<em>seldom</em> formed either in windy weather or on the tops of -mountains. Now, Aristotle reasoned in a subtle and able -manner on these two observations. He saw that dew must -be the result of processes which are interfered with when -the air is agitated, and which do not extend high above -the earth’s surface; he conjectured, therefore, that dew is -simply caused by the discharge of vapour from the air.<span class="pagenum"><a id="Page_359">359</a></span> -“Vapour is a mixture,” he said, “of water and heat, and as -long as water can get a supply of heat, vapour rises. But -vapour cannot rise high, or the heat would get detached -from it; and vapour cannot exist in windy weather, but -becomes dissipated. Hence, in high places, and in windy -weather, dew cannot be formed for want of vapour.” He -derided the notion that the stars and moon cause the precipitation -of dew. “On the contrary, the sun,” he said, -“is the cause; since its heat raises the vapour, from which -the dew is formed when that heat is no longer present to -keep up the vapour.”</p> - -<p>Amidst much that is false, there is here a good deal that -is sound. The notion that heat is some substance which -floats up the vapour, and may become detached from it in -high or windy places, is of course incorrect. So also is the -supposition that the dew is produced by the <em>fall</em> of condensed -vapour as the heat passes away. Nor is it correct -to say that the absence of the sun causes the condensation -of vapour, since, as we shall presently see, the cold which -causes the deposition of dew results from more than the -mere absence of the sun. But, in pointing out that the -discharge of vapour from the air, owing to loss of heat, is -the true cause of the deposition of dew, Aristotle expressed -an important truth. It was when he attempted to account -for the discharge that he failed. It will be observed, also, -that his explanation does not account for the observed fact -that dew is only formed in clear weather.</p> - -<p>Aristotle’s views did not find acceptance among the -Greeks or Romans; they preferred to look on the moon, -stars, and planets as the agents which cause the deposition -of dew. “This notion,” says a modern author, “was too -beautiful for a Greek to give up, and the Romans could not -do better than follow the example of their masters.”</p> - -<p>In the middle ages, despite the credit attached to -Aristotle’s name, those who cultivated the physical sciences -were unwilling to accept his views; for the alchemists (who -alone may be said to have been students of nature) founded<span class="pagenum"><a id="Page_360">360</a></span> -their hopes of success in the search for the philosopher’s -stone, the <i xml:lang="la" lang="la">elixir vitæ</i>, and the other objects of their pursuit, -on occult influences supposed to be exercised by the celestial -bodies. It was unlikely, therefore, that they would willingly -reject the ancient theory which ascribed dew to lunar and -stellar radiations.</p> - -<p>But at length Baptista Porta adduced evidence which -justified him in denying positively that the moon or stars -exercise any influence on the formation of dew. He discovered -that dew is sometimes deposited on the inside of -glass panes; and again, that a bell-glass placed over a plant -in cold weather is more copiously covered with dew within -than without; nay, he observed that even some opaque -substances show dew on their <em>under</em> surface when none -appears on the upper. Yet, singularly enough, Baptista -Porta rejected that part of Aristotle’s theory which was -alone correct. He thought his observations justified him in -looking on dew as condensed—not from vapour, as Aristotle -thought—but from the air itself.</p> - -<p>But now a new theory of dew began to be supported. -We have seen that not only the believers in stellar influence, -but Aristotle also, looked on dew as falling from above. -Porta’s experiments were opposed to this view. It seemed -rather as if dew rose from the earth. Observation also -showed that the amount of dew obtained at different heights -from the ground diminishes with the height. Hence, the -new theorists looked upon dew as an exhalation from the -ground and from plants—a fine steam, as it were, rising -upwards, and settling principally on the under surfaces of -objects.</p> - -<p>But this view, like the others, was destined to be overthrown. -Muschenbroek, when engaged in a series of observations -intended to establish the new view, made a -discovery which has a very important bearing on the theory of -dew: he found that, instead of being deposited with tolerable -uniformity upon different substances,—as falling rain is, -for instance, and as the rising rain imagined by the new<span class="pagenum"><a id="Page_361">361</a></span> -theorists ought to be,—dew forms very much more freely on -some substances than on others.</p> - -<p>Here was a difficulty which long perplexed physicists. -It appeared that dew neither fell from the sky nor arose -from the earth. The object itself on which the dew was -formed seemed to play an important part in determining the -amount of deposition.</p> - -<p>At length it was suggested that Aristotle’s long-neglected -explanation might, with a slight change, account for the -observed phenomena. The formation of dew was now -looked upon as a discharge of vapour from the air, this discharge -not taking place necessarily upwards or downwards, -but always from the air next to the object. But it was easy -to test this view. It was understood that the coldness of the -object, as compared with the air, was a necessary element -in the phenomenon. It followed, that if a cold object is -suddenly brought into warm air, there ought to be a deposition -of moisture upon the object. This was found to be the -case. Any one can readily repeat the experiment. If a -decanter of ice-cold water is brought into a warm room, in -which the air is not dry—a crowded room, for example—the -deposition of moisture is immediately detected by the -clouding of the glass. But there is, in fact, a much simpler -experiment. When we breathe, the moisture in the breath -generally continues in the form of vapour. But if we breathe -upon a window-pane, the vapour is immediately condensed, -because the glass is considerably colder than the exhaled air.</p> - -<p>But although this is the correct view, and though physicists -had made a noteworthy advance in getting rid of -erroneous notions, yet a theory of dew still remained to be -formed; for it was not yet shown how the cold, which causes -the deposition of dew, is itself occasioned. The remarkable -effects of a clear sky and serene weather in encouraging the -formation of dew, were also still unaccounted for. On the -explanation of these and similar points, the chief interest of -the subject depends. Science owes the elucidation of these -difficulties to Dr. Wells, a London physician, who studied<span class="pagenum"><a id="Page_362">362</a></span> -the subject of dew in the commencement of the present century. -His observations were made in a garden three miles -from Blackfriars Bridge.</p> - -<p>Wells exposed little bundles of wool, weighing, when -dry, ten grains each, and determined by their increase in -weight the amount of moisture which had been deposited -upon them. At first, he confined himself to comparing the -amount of moisture collected on different nights. He found -that although it was an invariable rule that cloudy nights -were unfavourable to the deposition of dew, yet that on some -of the very clearest and most serene nights, less dew was -collected than on other occasions. Hence it became evident -that mere clearness was not the only circumstance which -favoured the deposition of dew. In making these experiments, -he was struck by results which appeared to be -anomalous. He soon found that these anomalies were -caused by any obstructions which hid the heavens from his -wool-packs: such obstructions hindered the deposition of -dew. He tried a crucial experiment. Having placed a -board on four props, he laid a piece of wool <em>on</em> the board, -and another <em>under</em> it. During a clear night, he found that -the difference in the amount of dew deposited on the two -pieces of wool was remarkable: the upper one gained fourteen -grains in weight, the lower one gained only four grains. -He made a little roof over one piece of wool, with a sheet of -pasteboard; and the increase of weight was reduced to two -grains, while a piece of wool outside the roof gained no less -than sixteen grains in weight.</p> - -<p>Leaving these singular results unexplained for a while, -Dr. Wells next proceeded to test the temperature near his -wool-packs. He found that where dew is most copiously -produced, there the temperature is lowest. Now, since it is -quite clear that the deposition of dew was not the cause of -the increased cold—for the condensation of vapour is a process -<em>producing heat</em>—it became quite clear that the formation -of dew is dependent on and proportional to the loss of -heat.</p> - -<p><span class="pagenum"><a id="Page_363">363</a></span> -And now Wells was approaching the solution of the -problem he had set himself; for it followed from his observations, -that such obstructions as the propped board and the -pasteboard roof <em>kept in the heat</em>. It followed also, from the -observed effects of clear skies, that clouds <em>keep in the heat</em>. -Now, what sort of heat is that which is prevented from -escaping by the interference of screens, whether material or -vaporous? There are three processes by which heat is -transmitted from one body to another,—these are, conduction, -convection, and radiation. The first is the process by -which objects in contact communicate their heat to each -other, or by which the heat in one part of a body is gradually -transmitted to another part. The second is the process by -which heat is carried from one place to another by the absolute -transmission of heated matter. The third is that process -by which heat is spread out in all directions, in the -same manner as light. A little consideration will show that -the last process is that with which we are alone concerned; -and this important result flows from Dr. Wells’ experiments, -that <em>the rate of the deposition of dew depends on the rate at -which bodies part with their heat by radiation</em>. If the process -of radiation is checked, dew is less copiously deposited, and -<i xml:lang="la" lang="la">vice versâ</i>.</p> - -<p>When we consider the case of heat accompanied by -light, we understand readily enough that a screen may interfere -with the emission of radiant heat. We use a fire-screen, -for instance, with the object of producing just such an interference. -But we are apt to forget that what is true of -luminous heat is true also of that heat which every substance -possesses. In fact, we do not meet with many instances in -which the effect of screens in preventing the loss of obscure -heat is very noteworthy. There are some, as the warmth of -a green-house at night, and so on; but they pass unnoticed, -or are misunderstood. It was in this way that the explanation -of dew-phenomena had been so long delayed. The -very law on which it is founded had been <em>practically</em> applied, -while its meaning had not been recognized. “I had often<span class="pagenum"><a id="Page_364">364</a></span> -in the pride of half-knowledge,” says Wells, “smiled at the -means frequently employed by gardeners to protect tender -plants from cold, as it appeared to me impossible that a thin -mat, or any such flimsy substance, could prevent them from -attaining the temperature of the atmosphere, by which alone -I thought them liable to be injured. But when I had seen -that bodies on the surface of the earth become, during a still -and serene night, colder than the atmosphere, by radiating -their heat to the heavens, I perceived immediately a just -reason for the practice which I had before deemed useless.”</p> - -<p>And now all the facts which had before seemed obscure -were accounted for. It had been noticed that metallic plates -were often dry when grass or wood was copiously moistened. -Now, we know that metals part unwillingly with their heat -by radiation, and therefore the temperature of a metal plate -exposed in the open air is considerably higher than that of -a neighbouring piece of wood. For a similar reason, dew is -more freely deposited on grass than on gravel. Glass, again, -is a good radiator, so that dew is freely deposited on glass -objects,—a circumstance which is very annoying to the telescopist. -The remedy employed is founded on Wells’ observations—a -cylinder of tin or card, called a dew-cap, is made -to project beyond the glass, and thus to act as a screen, and -prevent radiation.</p> - -<p>We can now also interpret the effects of a clear sky. -Clouds act the part of screens, and check the emission of -radiant heat from the earth. This fact has been noticed -before, but misinterpreted, by Gilbert White of Selborne. -“I have often observed,” he says, “that cold seems to descend -from above; for when a thermometer hangs abroad on a -frosty night, the intervention of a cloud shall immediately raise -the mercury ten degrees, and a clear sky shall again compel -it to descend to its former gauge.” Another singular mistake -had been made with reference to the power which clouds -possess of checking the emission of radiant heat. It had -been observed that on moonlit nights the eyes are apt to -suffer in a peculiar way, which has occasionally brought on<span class="pagenum"><a id="Page_365">365</a></span> -temporary blindness. This had been ascribed to the moon’s -influence, and the term moon-blindness had therefore been -given to the affection. In reality, the moon has no more to -do with this form of blindness than the stars have to do with -the formation of dew. The absence of clouds from the air -is the true cause of the mischief. There is no sufficient -check to the radiation of heat from the eyeballs, and the -consequent chill results in temporary loss of sight, and sometimes -even in permanent injury.</p> - -<p>Since clouds possess this important power, it is clear that -while they are present in the air there can never be a copious -formation of dew, which requires, as we have seen, a considerable -fall in the temperature of the air around the place -of deposition. When the air is clear, however, radiation -proceeds rapidly, and therefore dew is freely formed.</p> - -<p>But it might seem that since objects in the upper regions -of the air part with their radiant heat more freely than -objects on the ground, the former should be more copiously -moistened with dew than the latter. That the fact is exactly -the reverse is thus explained. The cold which is produced -by the radiation of heat from objects high in the air is communicated -to the surrounding air, which, growing heavier, -descends towards the ground, its place being supplied by -warmer air. Thus the object is prevented from reducing the -air in its immediate neighbourhood to so low a temperature -as would be attained if this process of circulation were -checked. Hence, a concave vessel placed below an object -high in air, would serve to increase the deposition of dew by -preventing the transfer of the refrigerated air. We are not -aware that the experiment has ever been tried, but undoubtedly -it would have the effect we have described. An object -on the ground grows cold more rapidly, because the neighbouring -air cannot descend after being chilled, but continues -in contact with the object; also cold air is continually -descending from the neighbourhood of objects higher in air -which are parting with their radiant heat, and the cold air -thus descending takes the place of warmer air, whose neighbourhood<span class="pagenum"><a id="Page_366">366</a></span> -might otherwise tend to check the loss of heat in -objects on the ground.</p> - -<p>Here, also, we recognize the cause of the second peculiarity -detected by Aristotle—namely, that dew is only -formed copiously in serene weather. When there is wind, -it is impossible that the refrigerated air around an object -which is parting with its radiant heat, can remain long in -contact with the object. Fresh air is continually supplying -the place of the refrigerated air, and thus the object is prevented -from growing so cold as it otherwise would.</p> - -<p>In conclusion, we should wish to point out the important -preservative influence exercised during the formation of dew. -If the heat which is radiated from the earth, or from objects -upon it, during a clear night, were not repaired in any way, -the most serious injury would result to vegetation. For -instance, if the sun raised no vapour during the day, so that -when night came on the air was perfectly dry, and thus the -radiant heat passed away into celestial space without compensation, -not a single form of vegetation could retain its -life during the bitter cold which would result. But consider -what happens. The sun’s heat, which has been partly used -up during the day in supplying the air with aqueous vapour, -is gradually given out as this vapour returns to the form -of water. Thus the process of refrigeration is effectually -checked, and vegetation is saved from destruction. There -is something very beautiful in this. During the day, the -sun seems to pour forth his heat with reckless profusion, -yet all the while it is being silently stored up; during the -night, again, the earth seems to be radiating her heat too -rapidly into space, yet all the while a process is going on by -which the loss of heat is adequately compensated. Every -particle of dew which we brush from the blades of grass, as -we take our morning rambles, is an evidence of the preservative -action of nature.</p> - -<hr /> - -<p><span class="pagenum"><a id="Page_367">367</a></span></p> - -<div class="chapter"> -<h2><a id="THE_LEVELLING_POWER_OF_RAIN"></a><i>THE LEVELLING POWER OF RAIN.</i></h2> -</div> - -<p class="in0">It has been recognized, ever since geology has become truly -a science, that the two chief powers at work in remodelling -the earth’s surface, are fire and water. Of these powers one -is in the main destructive, and the other preservative. Were -it not for the earth’s vulcanian energies, there can be no -question that this world would long since have been rendered -unfit for life,—at least of higher types than we recognize -among sea creatures. For at all times igneous causes -are at work, levelling the land, however slowly; and this not -only by the action of sea-waves at the border-line between -land and water, but by the action of rain and flood over -inland regions. Measuring the destructive action of water -by what goes on in the lifetime of a man, or even during -many successive generations, we might consider its effects -very slight, even as on the other hand we might underrate -the effects of the earth’s internal fires, were we to limit our -attention to the effects of upheaval and of depression (not -less preservative in the long run) during a few hundreds or -thousands of years. As Lyell has remarked in his “Principles -of Geology,” “our position as observers is essentially unfavourable -when we endeavour to estimate the nature and -magnitude of the changes now in progress. As dwellers on -the land, we inhabit about a fourth part of the surface; and -that portion is almost exclusively a theatre of decay, and not -of reproduction. We know, indeed, that new deposits are -annually formed in seas and lakes, and that every year some<span class="pagenum"><a id="Page_368">368</a></span> -new igneous rocks are produced in the bowels of the earth, -but we cannot watch the progress of their formation; and as -they are only present to our minds by the aid of reflection, -it requires an effort both of the reason and the imagination -to appreciate duly their importance.” But that they are -actually of extreme importance, that in fact all the most -characteristic features of our earth at present are due to the -steady action of these two causes, no geologist now doubts.</p> - -<p>I propose now to consider one form in which the earth’s -aqueous energies effect the disintegration and destruction of -the land. The sea destroys the land slowly but surely, by -beating upon its shores and by washing away the fragments -shaken down from cliffs and rocks, or the more finely divided -matter abstracted from softer strata. In this work the sea is -sometimes assisted by the other form of aqueous energy—the -action of rain. But in the main, the sea is the destructive -agent by which shore-lines are changed. The other way in -which water works the destruction of the land affects the -interior of land regions, or only affects the shore-line by -removing earthy matter from the interior of continents to the -mouths of great rivers, whence perhaps the action of the sea -may carry it away to form shoals and sandbanks. I refer to -the direct and indirect effects of the downfall of rain. All -these effects, without a single exception, tend to level the -surface of the earth. The mountain torrent whose colour -betrays the admixture of earthy fragments is carrying those -fragments from a higher to a lower level. The river owes its -colour in like manner to earth which it is carrying down to -the sea level. The flood deposits in valleys matter which -has been withdrawn from hill slopes. Rainfall, acts, however, -in other ways, and sometimes still more effectively. -The soaked slopes of great hills give way, and great landslips -occur. In winter the water which has drenched the land -freezes, in freezing expands, and then the earth crumbles -and is ready to be carried away by fresh rains; or when dry, -by the action even of the wind alone. Landslips, too, are -brought about frequently in the way, which are even more<span class="pagenum"><a id="Page_369">369</a></span> -remarkable than those which are caused by the unaided -action of heavy rainfalls.</p> - -<p>The most energetic action of aqueous destructive forces -is seen when water which has accumulated in the higher -regions of some mountain district breaks its way through -barriers which have long restrained it, and rushes through -such channels as it can find or make for itself into valleys -and plains at lower levels. Such catastrophes are fortunately -not often witnessed in this country, nor when seen do they -attain the same magnitude as in more mountainous countries. -It would seem, indeed, as though they could attain very -great proportions only in regions where a large extent of -mountain surface lies above the snow-line. The reason why -in such regions floods are much more destructive than elsewhere -will readily be perceived if we consider the phenomena -of one of these terrible catastrophes.</p> - -<p>Take, for instance, the floods which inundated the plains -of Martigny in 1818. Early in that year it was found that -the entire valley of the Bagnes, one of the largest side-valleys -of the great valley of the Rhône, above Geneva, had been -converted into a lake through the damming up of a narrow -outlet by avalanches of snow and ice from a loftier glacier -overhanging the bed of the river Dranse. The temporary -lake thus formed was no less than half a league in length, -and more than 200 yards wide, its greatest depth exceeding -200 feet. The inhabitants perceived the terrible effects which -must follow when the barrier burst, which it could not fail to -do in the spring. They, therefore, cut a gallery 700 feet long -through the ice, while as yet the water was at a moderate -height. When the waters began to flow through this channel, -their action widened and deepened it considerably. At length -nearly half the contents of the lake were poured off. Unfortunately, -as the heat of the weather increased, the middle -of the barrier slowly melted away, until it became too weak to -withstand the pressure of the vast mass of water. Suddenly -it gave way; and so completely that all the water in the lake -rushed out in half an hour. The effects of this tremendous<span class="pagenum"><a id="Page_370">370</a></span> -outrush of the imprisoned water were fearful. “In the course -of their descent,” says one account of the catastrophe, “the -waters encountered several narrow gorges, and at each of -these they rose to a great height, and then burst with new -violence into the next basin, sweeping along forests, houses, -bridges, and cultivated land.” It is said by those who witnessed -the passage of the flood at various parts of its course, -that it resembled rather a moving mass of rock and mud -than a stream of water. “Enormous masses of granite were -torn out of the sides of the valleys, and whirled for hundreds -of yards along the course of the flood.” M. Escher the -engineer tells us that a fragment thus whirled along was -afterwards found to have a circumference of no less than -sixty yards. “At first the water rushed on at a rate of more -than a mile in three minutes, and the whole distance (forty-five -miles) which separates the Valley of Bagnes from the Lake -of Geneva was traversed in little more than six hours. The -bodies of persons who had been drowned in Martigny were -found floating on the further side of the Lake of Geneva, near -Vevey. Thousands of trees were torn up by the roots, and -the ruins of buildings which had been overthrown by the -flood were carried down beyond Martigny. In fact, the -flood at this point was so high, that some of the houses in -Martigny were filled with mud up to the second story.”</p> - -<p>It is to be noted respecting this remarkable flood, that -its effects were greatly reduced in consequence of the efforts -made by the inhabitants of the lower valleys to make an -outlet for the imprisoned waters. It was calculated by M. -Escher that the flood carried down 300,000 cubic feet of -water every second, an outflow five times as great as that of -the Rhine below Basle. But for the drawing off of the -temporary lake, the flood, as Lyell remarks, would have -approached in volume some of the largest rivers in Europe. -“For several months after the <i xml:lang="fr" lang="fr">débâcle</i> of 1818,” says Lyell, -“the Dranse, having no settled channel, shifted its position -continually from one side to the other of the valley, carrying -away newly erected bridges, undermining houses, and<span class="pagenum"><a id="Page_371">371</a></span> -continuing to be charged with as large a quantity of earthy -matter as the fluid could hold in suspension. I visited this -valley four months after the flood, and was witness to the -sweeping away of a bridge and the undermining of part of a -house. The greater part of the ice-barrier was then standing, -presenting vertical cliffs 150 feet high, like ravines in the -lava-currents of Etna, or Auvergne, where they are intersected -by rivers.” It is worthy of special notice that inundations -of similar or even greater destructiveness have occurred in -the same region at former periods.</p> - -<p>It is not, however, necessary for the destructive action of -floods in mountain districts that ice and snow should assist, -as in the Martigny flood. In October, 1868, the cantons of -Tessin, Grisons, Uri, Valois, and St. Gall, suffered terribly -from the direct effects of heavy rainfall. The St. Gothard, -Splugen, and St. Bernhardin routes were rendered impassable. -In the former pass twenty-seven lives were lost, -besides many horses and waggons of merchandise. On the -three routes more than eighty persons in all perished. In -the small village of Loderio alone, no less than fifty deaths -occurred. The damage in Tessin was estimated at £40,000. -In Uri and Valois large bridges were destroyed and carried -away. Everything attested the levelling power of rain; a -power which, when the rain is falling steadily on regions -whence it as steadily flows away, we are apt to overlook.</p> - -<p>It is not, however, necessary to go beyond our own country -for evidence of the destructive action of water. We have -had during the past few years very striking evidence in this -respect, which need scarcely be referred to more particularly -here, because it will be in the recollection of all our readers. -Looking over the annals of the last half-century only, we -find several cases in which the power of running water in -carrying away heavy masses of matter has been strikingly -shown. Consider, for instance, the effects of the flood in -Aberdeenshire and the neighbouring counties, early in -August, 1829. In the course of two days a great flood -extended itself over “that part of the north-east of Scotland<span class="pagenum"><a id="Page_372">372</a></span> -which would be cut off by two lines drawn from the head of -Loch Rannoch, one towards Inverness and the other to -Stonehaven.” The total length of various rivers in this -region which were flooded amounted to between 500 and 600 -miles. Their courses were marked everywhere by destroyed -bridges, roads, buildings, and crops. Sir T. D. Lauder -records “the destruction of thirty-eight bridges, and the -entire obliteration of a great number of farms and hamlets. -On the Nairn, a fragment of sandstone fourteen feet long -by three feet wide and one foot thick, was carried about 200 -yards down the river. Some new ravines were formed on -the sides of mountains where no streams had previously -flowed, and ancient river channels, which had never been -filled from time immemorial, gave passage to a copious -flood.” But perhaps the most remarkable effect of these -inundations was the entire destruction of the bridge over the -Dee at Ballater. It consisted of five arches, spanning a -waterway of 260 feet. The bridge was built of granite, -the pier, resting on rolled pieces of granite and gneiss. -We read that the different parts of this bridge were -swept away in succession by the flood, the whole mass of -masonry disappearing in the bed of the river. Mr. Farquharson -states that on his own premises the river Don forced -a mass of 400 or 500 tons of stones, many of them of 200 or -300 pounds’ weight, up an inclined plane, rising six feet in -eight or ten yards, and left them in a rectangular heap about -three feet deep on a flat ground, the heap ending abruptly at -its lower extremity.” At first sight this looks like an action -the reverse of that levelling action which we have here -attributed to water. But in reality it indicates the intense -energy of this action; which drawing heavy masses down -along with swiftly flowing water, communicates to them so -great a momentum, that on encountering in their course a -rising slope, they are carried up its face and there left by the -retreating flood. The rising of these masses no more -indicates an inherent uplifting power in running water, than -the ascent of a gently rising slope by a mass which has rolled<span class="pagenum"><a id="Page_373">373</a></span> -headlong down the steep side of a hill indicates an upward -action exerted by the force of gravity.</p> - -<p>Even small rivers, when greatly swollen by rain, exhibit -great energy in removing heavy masses. Thus Lyell -mentions that in August, 1827, the College, a small river -which flows down a slight declivity from the eastern watershed -of the Cheviot Hills, carried down several thousand -tons’ weight of gravel and sand to the plain of the Till. This -little river also carried away a bridge then in process of -building, “some of the arch stones of which, weighing from -half to three-quarters of a ton each, were propelled two miles -down the rivulet.” “On the same occasion the current tore -away from the abutment of a mill-dam a large block of greenstone -porphyry, weighing nearly two tons, and transported it -to a distance of nearly a quarter of a mile. Instances are -related as occurring repeatedly, in which from 1000 to 3000 -tons of gravel are in like manner removed by this streamlet -to still greater distances in one day.”</p> - -<p>It may appear, however, to the reader that we have in -such instances as these the illustration of destructive agencies -which are of their very nature limited within very narrow -areas. The torrent, or even the river, may wear out its bed -or widen it, but nevertheless can hardly be regarded as -modifying the aspect of the region through which it flows. -Even in this respect, however, the destructive action of water -is not nearly so limited as it might appear to be. Taking a -few centuries or a few thousand years, no doubt, we can -attribute to the action of rivers, whether in ordinary flow or -in flood, little power of modifying the region which they -drain. But taking that wider survey (in time) of fluviatile -work which modern science requires, dealing with this form -of aqueous energy as we deal with the earth’s vulcanian -energies, we perceive that the effects of river action in the -course of long periods of time are not limited to the course -which at any given time a river may pursue. In carrying -down material along its course to the sea, a river is not -merely wearing down its own bed, but is so changing it that<span class="pagenum"><a id="Page_374">374</a></span> -in the course of time it will become unfit to drain the region -through which it flows. Its bottom must of necessity become -less inclined. Now although it will then be lower than at -present, and therefore be then even more than now the place -to which the water falling upon the region traversed by the -river will naturally tend, it will no longer carry off that water -with sufficient velocity. Three consequences will follow -from this state of things. In the first place there will be -great destruction in the surrounding region through floods -because of inadequate outflow; in the second place, the -overflowing waters will in the course of time find new -channels, or in other words new rivers will be formed in -this region; thirdly, owing to the constant presence of large -quantities of water in the depressed bed of the old river, the -banks on either side will suffer, great landslips occurring and -choking up its now useless channel. Several rivers are -undergoing these changes at the present time, and others, -which are manifestly unfit for the work of draining the region -through which they flow (a circumstance attested by the -occurrence of floods in every wet season), must before long -be modified in a similar way.</p> - -<p>We are thus led to the consideration of the second form -in which the destructive action of inland waters, or we may -truly say, the destructive action of <em>rain</em>, is manifested,—viz., -in landslips. These, of course, are also caused not -unfrequently by vulcanian action, but equally of course landslips -so caused do not belong to our present subject. Landslips -caused directly or indirectly by rain, are often quite -as extensive as those occasioned by vulcanian energy, and -they are a great deal more common. We may cite as a -remarkable instance a landslip of nearly half a mile in -breadth, now in progress, in a district of the city of Bath -called Hedgmead, which forms a portion of the slope of -Beacon Hill. It is attributed to the action of a subterranean -stream on a bed of gravel, the continued washing away of -which causes the shifting; but the heavy rains of 1876–77 -caused the landslip to become much more marked.</p> - -<p><span class="pagenum"><a id="Page_375">375</a></span> -Besides slow landslips, however, rain not unfrequently -causes great masses of earth to be precipitated suddenly, -and where such masses fall into the bed of a river, local -deluges of great extent and of the most destructive character -often follow. The following instances, cited in an abridged -form from the pages of Lyell’s “Principles of Geology,” attest -the terrible nature of catastrophes such as these.</p> - -<p>Two dry seasons in the White Mountains of New Hampshire -were followed by heavy rains on August 28, 1826. -From the steep and lofty slopes of the River Saco great -masses of rock and stone were detached, and descending -carried along with them “in one promiscuous and frightful -ruin, forests, shrubs, and the earth which sustained them.” -“Although there are numerous indications on the steep -sides of these hills of former slides of the same kind, yet no -tradition had been handed down of any similar catastrophe -within the memory of man, and the growth of the forest on -the very spots now devastated clearly showed that for a -long interval nothing similar had occurred. One of these -moving masses was afterwards found to have slid three -miles, with an average breadth of a quarter of a mile.” At -the base of the vast chasms formed by these natural excavations, -a confused mass of ruins was seen, consisting of transported -earth, gravel, rocks, and trees. Forests were prostrated -with as much ease as if they had been mere fields of grain; -if they resisted for a while, “the torrent of mud and rock -accumulated behind till it gathered sufficient force to burst -the temporary barrier.” “The valleys of the Amonoosuck -and Saco presented, for many miles, an uninterrupted scene -of desolation, all the bridges being carried away, as well -as those over the tributary streams. In some places -the road was excavated to the depth of from fifteen to -twenty feet; in others it was covered with earth, rocks, and -trees to as great a height. The water flowed for many weeks -after the flood, as densely charged with earth as it could be -without being changed into mud, and marks were seen in -various localities of its having risen on either side of the<span class="pagenum"><a id="Page_376">376</a></span> -valley to more than twenty-five feet above the ordinary -level.” But perhaps the most remarkable evidence of the -tremendous nature of this cataclysm is to be found in Lyell’s -statements respecting the condition of the region nineteen -years later. “I found the signs of devastation still very -striking,” he says; “I also particularly remarked that the -surface of the bare granite rocks had been smoothed by -the passage over them of so much mud and stone.” Professor -Hubbard mentions in <cite>Silliman’s Journal</cite> that “in -1838 the deep channels worn by the avalanches of mud -and stone, and the immense heaps of boulders and blocks of -granite in the river channel, still formed a picturesque feature -in the scenery.”</p> - -<p>It will readily be understood that when destruction such -as this follows from landslips along the borders of insignificant -rivers, those occurring on the banks of the mighty -rivers which drain whole continents are still more terrible. -The following account from the pen of Mr. Bates the -naturalist, indicates the nature of the landslips which occur -on the banks of the Amazon. “I was awoke before sunrise, -one morning,” he says, “by an unusual sound resembling -the roar of artillery; the noise came from a considerable -distance, one crash succeeding another. I supposed it to -be an earthquake, for, although the night was breathlessly -calm, the broad river was much agitated, and the vessel -rolled heavily. Soon afterwards another loud explosion -took place, followed by others which lasted for an hour till -the day dawned, and we then saw the work of destruction -going forward on the other side of the river, about three -miles off. Large masses of forest, including trees of colossal -size, probably 200 feet in height, were rocking to and fro, -and falling headlong one after another into the water. After -each avalanche the wave which it caused returned on the -crumbly bank with tremendous force, and caused the fall -of other masses by undermining. The line of coast over -which the landslip extended was a mile or two in length; -the end of it, however, was hid from our view by an intervening<span class="pagenum"><a id="Page_377">377</a></span> -island. It was a grand sight; each downfall created a -cloud of spray; the concussion in one place causing other -masses to give way a long distance from it, and thus the -crashes continued, swaying to and fro, with little prospect of -termination. When we glided out of sight two hours after -sunrise the destruction was still going on.”</p> - -<p>We might consider here the action of glaciers in gradually -grinding down the mountain slopes, the destructive action -of avalanches, and a number of other forms in which snow -and ice break down by slow degrees the upraised portions -of the earth. For in reality all these forms of destructive -action take their origin in the same process whence running -waters and heavy rainfalls derive their power. All these -destructive agencies are derived from the vapour of water -in the air. But it seems better to limit the reader’s attention -in this place to the action of water in the liquid form; and -therefore we proceed to consider the other ways in which -rain wears down the land.</p> - -<p>Hitherto we have considered effects which are produced -chiefly along the courses of rivers, or in their neighbourhood. -But heavy rainfall acts, and perhaps in the long run as -effectively (when we remember the far wider region affected) -over wide tracts of nearly level ground, as along the banks -of torrents and rivers.</p> - -<p>The rain which falls on plains or gently undulating -surfaces, although after a while it dries up, yet to some -degree aids in levelling the land, partly by washing down -particles of earth, however slowly, to lower levels, partly by -soaking the earth and preparing a thin stratum of its upper -surface to be converted into dust, and blown away by the -wind. But it is when very heavy storms occur that the -levelling action of rain over widely extending regions can -be most readily recognized. Of this fact observant travellers -cannot fail to have had occasional evidence. Sir Charles -Lyell mentions one instance observed by him, which is -specially interesting. “During a tour in Spain,” he says, -“I was surprised to see a district of gently undulating<span class="pagenum"><a id="Page_378">378</a></span> -ground in Catalonia, consisting of red and grey sandstone, -and in some parts of red marl, almost entirely denuded of -herbage, while the roots of the pines, holm oaks, and some -other trees, were half exposed, as if the soil had been -washed away by a flood. Such is the state of the forests, -for example, between Oristo and Vich, and near San -Lorenzo. But being overtaken by a violent thunderstorm, -in the month of August, I saw the whole surface, even the -highest levels of some flat-topped hills, streaming with mud, -while on every declivity the devastation of torrents was -terrific. The peculiarities in the physiognomy of the -district were at once explained, and I was taught that, in -speculating on the greater effects which the direct action of -rain may once have produced on the surface of certain parts -of England, we need not revert to periods when the heat of -the climate was tropical.” He might have cited instances -of such storms occurring in England. For example, White, -in his delightful “Natural History of Selborne,” describes -thus the effects of a storm which occurred on June 5, 1784: -“At about a quarter after two the storm began in the parish -of Harpley, moving slowly from north to south, and from -thence it came over Norton Farm and so to Grange Farm, -both in this parish. Had it been as extensive as it was -violent (for it was very short) it must have ravaged all the -neighbourhood. The extent of the storm was about two -miles in length and one in breadth. There fell prodigious -torrents of rain on the farms above mentioned, which -occasioned a flood as violent as it was sudden, doing great -damage to the meadows and fallows by deluging the one -and washing away the soil of the other. The hollow lane -towards Alton was so torn and disordered as not to be -passable till mended, rocks being removed which weighed -two hundredweight.”</p> - -<p>We have mentioned the formation of dust, and the -action of wind upon it, as a cause tending to level the surface -of the land. It may appear to many that this cause is too insignificant -to be noticed among those which modify the earth’s<span class="pagenum"><a id="Page_379">379</a></span> -surface. In reality, however, owing to its continuous action, -and to its always acting (in the main) in one direction, this -cause is much more important than might be supposed. -We overlook its action as actually going on around us, -because in a few years, or in a few generations, it produces -no change that can be readily noticed. But in long periods -of time it changes very markedly the level of lower lands, -and that too even in cities, where means exist for removing -the accumulations of dust which are continually collecting on -the surface of the earth. We know that the remains of old -Roman roads, walls, houses, and so forth, in this country, are -found, not at the present level of the surface, but several -feet—in some cases many yards—below this level. The -same holds elsewhere, under the same conditions—that is, -where we know quite certainly that the substances thus found -underground were originally on the surface, and that there -has been neither any disturbance causing them to be -engulfed, nor any deposition of scoriæ, volcanic dust, or -other products of subterranean disturbance. We cannot -hesitate to regard this burying of old buildings as due to the -continual deposition of dust, which eventually becomes compacted -into solid earth. We know, moreover, that the -formation of dust is in the main due to rain converting -the surface layers of the earth into mud, which on drying -requires but the frictional action of heavy winds to rise in -clouds of dust. In some soils this process goes on more -rapidly than in others, as every one who has travelled much -afoot is aware. There are parts of England, for instance, -where, even in the driest summer, the daily deposition of -dust on dry and breezy days is but slight, others where in -such weather a dust layer at least a quarter of an inch in -thickness is deposited in the course of a day. If we assumed, -which would scarcely seem an exaggerated estimate, that in -the course of a single year a layer of dust averaging an inch -in thickness is deposited over the lower levels of the surface -of the land, we should find that the average depth of the -layer formed in the last thousand years would amount to no<span class="pagenum"><a id="Page_380">380</a></span> -less than eighty-three feet. Of course in inhabited places -the deposition of dust is checked, though not so much as -most persons imagine. There is not probably in this -country a single building five hundred years old, originally -built at a moderately low level, the position of whose foundation -does not attest the constant gathering of matter upon -the surface. The actual amount by which the lower levels -are raised and the higher levels diminished in the course of -a thousand years may be very much less, but that it must -amount to many feet can scarcely be questioned.</p> - -<p>And as in considering the action of rain falling over a -wide range of country, we have to distinguish between the -slow but steady action of ordinary rains and the occasional -violent action of great storms of rain, so in considering the -effects of drought following after rain which has well saturated -the land we have to distinguish between ordinarily dusty -times and occasions when in a very short time, owing to the -intensity of the heat and the violence of the wind large quantities -of dust are spread over a wide area. Darwin thus describes -the effect of such exceptional drought, as experienced in the -years 1827–1832 in Buenos Ayres:—“So little rain fell that -the vegetation, even to the thistles, failed; the brooks were -dried up, and the whole country assumed the appearance of -a dusty high road. This was especially the case in the -northern part of the province of Buenos Ayres, and the -southern part of Santa Fé.” He describes the loss of life -caused by the want of water, and many remarkable circumstances -of the drought which do not here specially concern -us. He then goes on to speak of the dust which gathered -over the open country. “Sir Woodbine Parish,” he says, -“informed me of a very curious source of dispute. The -ground being so long dry, such quantities of dust were -blown about that in this open country the landmarks became -obliterated, and people could not tell the limits of their -estates.” The dust thus scattered over the land, whether -left or removed, necessarily formed part of the solid material -brought from higher to lower levels, indirectly (in this case)<span class="pagenum"><a id="Page_381">381</a></span> -through the action of rain; for a drought can only convert -into friable matter earth which has before been thoroughly -soaked. But the action of rain, which had originally led -to the formation of these enormous masses of dust, presently -took part in carrying the dust in the form of mud to yet -lower levels. “Subsequently to the drought of 1827 to -1832,” proceeds Darwin, “a very rainy season followed, which -caused great floods. Hence it is almost certain that some -thousands of the skeletons” (of creatures whose deaths he -had described before) “were buried by the deposits of the -very next year. What could be the opinion of a geologist, -viewing such an enormous collection of bones, of all kinds of -animals and of all ages, thus embedded in one thick earthy -mass? Would he not attribute it to a flood having swept -over the surface of the land, rather than to the common -order of things?” In fact, a single great drought, followed -by a very rainy season, must in this instance, which was -however altogether exceptional, have produced a layer or -stratum such as geologists would ordinarily regard as the -work of a much longer time and much more potent disturbing -causes.</p> - -<p>It may be well to consider in this place the question -whether in reality the quantity of rain which falls now during -our winter months does not greatly exceed that which formerly -fell in that part of the year. The idea is very prevalent -that our winters have changed entirely in character in -recent times, and the fear (or the hope?) is entertained that -the change may continue in the same direction until wet and -mild winters replace altogether the cold which prevailed in -former years. There is no sufficient reason, however, for -supposing that any such change is taking place. It is, indeed, -not difficult to find in the meteorological annals of the -first half of the present century, instances of the occurrence -of several successive winters very unlike the greater number -of those which we have experienced during the last ten or -twelve years. But if we take any considerable series of -years in the last century we find the alternations of the<span class="pagenum"><a id="Page_382">382</a></span> -weather very similar to those we at present recognize. -Consider, for instance, Gilbert White’s brief summary of the -weather from 1768 onwards:—</p> - -<p>For the winter of 1768–69 we have October and the first -part of November rainy; thence to the end of 1768 alternate -rains and frosts; January and February frosty and rainy, -with gleams of fine weather; to the middle of March, wind -and rain.</p> - -<p>For the winter of 1769–70 we have October frosty, the -next fortnight rainy, the next dry and frosty. December -windy, with rain and intervals of frost (the first fortnight -very foggy); the first half of January frosty, thence to the -end of February mild hazy weather. March frosty and -brighter.</p> - -<p>For 1770–71, from the middle of October to the end of -the year, almost incessant rains; January severe frosts till -the last week, the next fortnight rain and snow, and spring -weather to the end of February. March frosty.</p> - -<p>For 1771–72, October rainy, November frost with intervals -of fog and rain, December bright mild weather with -hoar frosts; then six weeks of frost and snow, followed by -six of frost, sleet, hail, and snow.</p> - -<p>For 1772–73, October, November, and to December 22, -rain, with mild weather; to the end of 1772, cold foggy -weather; then a week of frost, followed by three of dark -rainy weather. First fortnight of February frost; thence to -the end of March misty showery weather.</p> - -<p>Passing over the winter of 1773–74, which was half -rainy, half frosty, what could more closely resemble the -winter weather we have had so much of during the last -few years, than that experienced in the winter of 1774–75? -From August 24 to the third week of November, there was -rain, with frequent intervals of sunny weather; to the end of -December, dark dripping fogs; to the end of the first fortnight -in March, rain almost every day.</p> - -<p>And so on, with no remarkable changes, until the year -1792, the last of Gilbert White’s records.</p> - -<p><span class="pagenum"><a id="Page_383">383</a></span> -If we limit our attention to any given month of winter, -we find the same mixture of cold and dry with wet and -open weather as we are familiar with at present. Take, for -instance, the month usually the most wintry of all, viz., -January. Passing over the years already considered, we -have January, 1776, dark and frosty with much snow till the -26th (at this time the Thames was frozen over), then foggy -with hoar frost; January, 1777, frosty till the 10th, then foggy -and showery; 1778, frosty till the 13th, then rainy to the -24th, then hard frost; 1779, frost and showers throughout -January; 1780, frost throughout; 1781, frost and snow to -the 25th, then rain and snow; 1782, open and mild; 1783, -rainy with heavy winds; 1784, hard frost; 1785, a thaw on -the 2nd, then rainy weather to the 28th, the rest of the -month frosty; 1786, frost and snow till January 7, then a -week mild with much rain, the next week heavy snow, and -the rest mild with frequent rain; 1787, first twenty-four -days dark moist mild weather, then four days frost, the rest -mild and showery; 1788, thirteen days mild and wet, five -days of frost, and from January 18 to the end of the month -dry windy weather; 1789, thirteen days hard frost, the rest -of the month mild with showers; 1790, sixteen days of -mild foggy weather with occasional rain, to the 21st frost, -to the 28th dark with driving rains, and the rest mild dry -weather; 1791, the whole of January mild with heavy rains; -and lastly 1792, “some hard frost in January, but mostly -wet and mild.”</p> - -<p>There is nothing certainly in this record to suggest that -any material change has taken place in our January weather -during the last eight years. And if we had given the record -of the entire winter for each of the years above dealt with -the result would have been the same.</p> - -<p>We have, in fact, very striking evidence in Gilbert -White’s account of the cold weather of December, 1784, -which he specially describes as “very extraordinary,” to -show that neither our severe nor our average winter weather -can differ materially from that which people experienced<span class="pagenum"><a id="Page_384">384</a></span> -in the eighteenth century. “In the evening of December -9,” he says, “the air began to be so very sharp that we -thought it would be curious to attend to the motions of a -thermometer; we therefore hung out two, one made by -Martin and one by Dolland” (<i xml:lang="la" lang="la">sic</i>, presumably Dollond), -“which soon began to show us what we were to expect; -for by ten o’clock they fell to twenty-one, and at eleven to -four, when we went to bed. On the 10th, in the morning -the quicksilver in Dolland’s glass was down to half a degree -below zero, and that of Martin’s, which was absurdly -graduated only to four degrees above zero, sank quite into -the brass guard of the ball, so that when the weather became -most interesting this was useless. On the 10th, at -eleven at night, though the air was perfectly still, Dolland’s -glass went down to one degree below zero!” The note of -exclamation is White’s. He goes on to speak of “this -strange severity of the weather,” which was not exceeded -that winter, or at any time during the twenty-four years of -White’s observations. Within the last quarter of a century, -the thermometer, on more than one occasion, has shown -two or three degrees below zero. Certainly the winters -cannot be supposed to have been ordinarily severer than -ours in the latter half of the last century, when we find that -thermometers, by well-known instrument makers, were so -constructed as to indicate no lower temperature than four -degrees above zero.</p> - -<p>Let us return, after this somewhat long digression, to the -levelling action of rain and rivers.</p> - -<p>If we consider this action alone, we cannot but recognize -in it a cause sufficient to effect the removal of all the higher -parts of the land to low levels, and eventually of all the -low-lying land to the sea, in the course of such periods as -geology makes us acquainted with. The mud-banks at the -mouths of rivers show only a part of what rain and river -action is doing, yet consider how enormous is the mass -which is thus carried into the sea. It has been calculated -that in a single week the Ganges alone carries away from the<span class="pagenum"><a id="Page_385">385</a></span> -soil of India and delivers into the sea twice as much solid -substance as is contained in the great pyramid of Egypt. -“The Irrawaddy,” says Sir J. Herschel, “sweeps off from -Burmah 62 cubit feet of earth in every second of time on -an average, and there are 86,400 seconds in every day, and -365 days in every year; and so on for other rivers. Nor is -there any reason to fear or hope that the rains will cease, -and this destructive process come to an end. For though -the quantity of water on the surface of the earth is probably -undergoing a slow process of diminution, small -portions of it year by year taking their place as waters under -the earth,<a id="FNanchor_44" href="#Footnote_44" class="fnanchor">44</a> yet these processes are far too slow to appreciably -affect the supply of water till a far longer period has elapsed -than that during which (in all probability) life can continue -upon the earth.</p> - -<p>When we consider the force really represented by the -downfall of rain, we need not greatly wonder that the<span class="pagenum"><a id="Page_386">386</a></span> -levelling power of rain is so effective. The sun’s heat is -the true agent in thus levelling the earth, and if we regard, -as we justly may, the action of water, whether in the form -of rain or river, or of sea-wave raised by wind or tide, as -the chief levelling and therefore destructive force at work -upon the earth, and the action of the earth’s vulcanian -energies as the chief restorative agent, then we may fairly -consider the contest as lying between the sun’s heat and the -earth’s internal heat. There can be little question as to -what would be the ultimate issue of the contest if land and -sea and air all endured or were only so far modified as they -were affected by these causes. Sun-heat would inevitably -prevail in the long run over earth-heat. But we see from -the condition of our moon how the withdrawal of water -and air from the scene must diminish the sun’s power of -levelling the irregularities of the earth’s surface. We say -advisedly <em>diminish</em>, not <em>destroy</em>; for there can be no question -that the solar heat alternating with the cold of the long -lunar night is still at work levelling, however slowly, the -moon’s surface; and the same will be the case with our -earth when her oceans and atmosphere have disappeared by -slow processes of absorption.</p> - -<p>The power actually at work at present in producing rain, -and so, indirectly, in levelling the earth’s surface, is enormous. -I have shown that the amount of heat required -to evaporate a quantity of water which would cover an area -of 100 square miles to a depth of one inch would be equal -to the heat which would be produced by the combustion -of half a million tons of coals, and that the amount of force -of which this consumption of heat would be the equivalent -corresponds to that which would be required to raise a -weight of upwards of one thousand millions of tons to a -height of one mile.<a id="FNanchor_45" href="#Footnote_45" class="fnanchor">45</a> When we remember that the land -surface of the earth amounts to about fifty millions of square -miles, we perceive how enormous must be the force-equivalent -of the annual rainfall of our earth. We are apt to<span class="pagenum"><a id="Page_387">387</a></span> -overlook when contemplating the silent and seemingly quiet -processes of nature—such as the formation of the rain-cloud -or the precipitation of rain—the tremendous energy of the -forces really causing these processes. “I have seen,” says -Professor Tyndall, “the wild stone-avalanches of the Alps, -which smoke and thunder down the declivities with a -vehemence almost sufficient to stun the observer. I have -also seen snow-flakes descending so softly as not to hurt the -fragile spangles of which they were composed; yet to produce -from aqueous vapour a quantity which a child could -carry of that tender material demands an exertion of energy -competent to gather up the shattered blocks of the largest -stone-avalanche I have ever seen, and pitch them to twice -the height from which they fell.”</p> - -<hr /> - -<p><span class="pagenum"><a id="Page_388">388</a></span></p> - -<div class="chapter"> -<h2><a id="ANCIENT_BABYLONIAN_ASTROGONY"></a><i>ANCIENT BABYLONIAN ASTROGONY.</i></h2> -</div> - -<p class="in0">It is singular to consider how short a time elapsed, after -writings in the arrow-headed or cuneiform letters (the Keilschriften -of the Germans) were discovered, before, first, the -power of interpreting them was obtained, and, secondly, the -range of the cuneiform literature (so to speak) was recognized. -Not more than ninety years have passed since the first specimens -of arrow-headed inscriptions reached Europe. They -had been known for a considerable time before this. -Indeed, it has been supposed that the Assyrian letters -referred to by Herodotus, Thucydides, and Pliny, were in this -character. Della Valle and Figueroa, early in the seventeenth -century, described inscriptions in arrow-headed letters, -and hazarded the idea that they are to be read from left to -right. But no very satisfactory evidence was advanced to -show whether the inscriptions were to be so read, or from -right to left, or, as Chardin suggested, in vertical lines. The -celebrated Olaus Gerhard Tychsen, of Rostock, and other -German philologists, endeavoured to decipher the specimens -which reached Europe towards the end of the last century; -but their efforts, though ingenious and zealous, were not -rewarded with success. In 1801 Dr. Hager advanced the -suggestion that the combinations formed by the arrow-heads -did not represent letters but words, if not entire sentences. -Lichtenstein, on the other hand, maintained that the letters -belonged to an old form of the Arabic or Coptic character;<span class="pagenum"><a id="Page_389">389</a></span> -and he succeeded to his own satisfaction in finding various -passages from the Koran in the cuneiform inscriptions. Dr. -Grotefend was the first to achieve any real success in this -line of research. It is said that he was led to take up the -subject by a slight dispute with one of his friends, which led -to a wager that he would decipher one of the cuneiform -inscriptions. The results of his investigations were that -cuneiform inscriptions are alphabetical, not hieroglyphical; -that the language employed is the basis of most of the -Eastern languages; and that it is written from right to left. -Since his time, through the labours of Rich, Botta, Rawlinson, -Hincks, De Saulcy, Layard, Sayce, George Smith, and -others, the collection and interpretation of the arrow-headed -inscriptions have been carried out with great success. We -find reason to believe that, though the original literature of -Babylon was lost, the tablet libraries of Assyria contained -copies of most of the writings of the more ancient nation. -Amongst these have been found the now celebrated descriptions -of the Creation, the Fall of Man, the Deluge, the Tower -of Babel, and other matters found in an abridged and -expurgated form in the book of Genesis. It is to that -portion of the Babylonian account which relates to the -creation of the sun and moon and stars that I wish here to -call attention. It is not only curious in itself, but throws -light, in my opinion, on questions of considerable interest -connected with the views of ancient Eastern nations respecting -the heavenly bodies.</p> - -<p>It may be well, before considering the passage in question, -to consider briefly—though we may not be able definitely -to determine—the real antiquity of the Babylonian -account.</p> - -<p>In Smith’s interesting work on the Chaldæan account of -Genesis, the question whether the Babylonian account preceded -the writing of the book of Genesis, or <i xml:lang="la" lang="la">vice versâ</i>, is -not definitely dealt with. Probably this part of his subject -was included among the “important comparisons and conclusions -with respect to Genesis” which he preferred to<span class="pagenum"><a id="Page_390">390</a></span> -avoid, as his “desire was first to obtain the recognition of the -evidence without prejudice.” It might certainly have interfered -to some degree with the unprejudiced recognition of -the evidence of the tablets if it had been maintained by him, -and still more if he had demonstrated, that the Babylonian -is the earlier version. For the account in the book of -Genesis, coming thus to be regarded as merely an expurgated -version of a narrative originally containing much fabulous -matter, and not a little that is monstrous and preposterous, -would certainly not have been presented to us in quite that -aspect in which it had long been regarded by theologians.</p> - -<p>But although Mr. Smith states that he placed the various -dates as low as he fairly could, considering the evidence,—nay, -that he “aimed to do this rather than to establish any -system of chronology,”—there can be no mistake about the -relative antiquity which he in reality assigns to the Babylonian -inscriptions. He states, indeed, that every copy of the -Genesis legends belongs to the reign of Assurbanipal, who -reigned over Assyria <span class="smcap smaller">B.C.</span> 670. But it is “acknowledged on -all hands that the tablets are not the originals, but are only -copies from earlier texts.” The Assyrians acknowledge -themselves that this literature was borrowed from Babylonian -sources, and of course it is to Babylonia we have to look to -ascertain the approximate dates of the original documents. -“The difficulty,” he proceeds, “is increased by the following -considerations: it appears that at an early period in Babylonian -history a great literary development took place, and -numerous works were produced which embodied the prevailing -myths, religion, and science of that day. Written, -many of them, in a noble style of poetry on one side, or -registering the highest efforts of their science on the other, -these texts became the standards for Babylonian literature, -and later generations were content to copy these writings -instead of making new works for themselves. Clay, the -material on which they were written, was everywhere -abundant, copies were multiplied, and by the veneration in -which they were held these texts fixed and stereotyped the<span class="pagenum"><a id="Page_391">391</a></span> -style of Babylonian literature, and the language in which -they were written remained the classical style in the country -down to the Persian conquest. Thus it happens that texts -of Rim-agu, Sargon, and Hammurabi, who were 1000 years -before Nebuchadnezzar and Nabonidus, show the same -language as the texts of these later kings, there being no -sensible difference in style to match the long interval -between them,”—precisely as a certain devotional style of -writing of our own day closely resembles the style of the -sixteenth century.</p> - -<p>We cannot, then, from the style, determine the age of the -original writings from which the Assyrian tablets were copied. -But there are certain facts which enable us to form an opinion -on this point. Babylonia was conquered about <span class="smcap smaller">B.C.</span> 1300, -by Tugultininip, king of Assyria. For 250 years before that -date a foreign race (called by Berosus, Arabs) had ruled in -Babylonia. There is no evidence of any of the original -Babylonian Genesis tablets being written after the date of -Hammurabi, under whom it is supposed that this race -obtained dominion in Babylonia. Many scholars, indeed, -regard Hammurabi as much more ancient; but none set -him later than 1550 <span class="smcap smaller">B.C.</span></p> - -<p>Now, before the time of Hammurabi several races of -kings reigned, their reigns ranging over a period of 500 -years. They were called chiefly Kings of Sumir and Akkad—that -is, Kings of Upper and Lower Babylonia. It is believed -that before this period,—ranging, say, from about -2000 <span class="smcap smaller">B.C.</span> to 1550 <span class="smcap smaller">B.C.</span> (at least not later, though possibly, and -according to many scholars, probably, far earlier),—the two -divisions of Babylonia were separate monarchies. Thus, -evidence whether any literature was written before or after -<span class="smcap smaller">B.C.</span> 2000, may be found in the presence or absence of -mention, or traces, of this division of the Babylonian kingdom. -Mr. Smith considers, for example, that two works,—the -great Chaldæan work on astrology, and a legend which -he calls “The Exploits of Lubara,”—certainly belong to the -period preceding <span class="smcap smaller">B.C.</span> 2000. In the former work, the subject<span class="pagenum"><a id="Page_392">392</a></span> -of which specially connects it, as will presently be seen, -with the tablet relating to the creation of the heavenly -bodies, Akkad is always referred to as a separate state.</p> - -<p>Now Mr. Smith finds that the story of the Creation and -Fall belongs to the upper or Akkad division of the country. -The Izdubar legends, containing the story of the Flood, and -what Mr. Smith regards as probably the history of Nimrod, -seem to belong to Sumir, the southern division of Babylonia. -He considers the Izdubar legends to have been written at -least as early as <span class="smcap smaller">B.C.</span> 2000. The story of the Creation “may -not have been committed to writing so early;” but it also is -of great antiquity. And these legends “were traditions -before they were committed to writing, and were common, -in some form, to all the country.” Remembering Mr. -Smith’s expressed intention of setting all dates as late as -possible, his endeavour to do this rather than to establish -any system of chronology, we cannot misunderstand the real -drift of his arguments, or the real significance of his conclusion -that the period when the Genesis tablets were -originally written extended from <span class="smcap smaller">B.C.</span> 2000 to <span class="smcap smaller">B.C.</span> 1550, or -roughly synchronized with the period from Abraham to -Moses, according to the ordinary chronology of our Bibles. -“During this period it appears that traditions of the creation -of the universe, and human history down to the time of -Nimrod, existed parallel to, and in some points identical -with, those given in the book of Genesis.”</p> - -<p>Thus viewing the matter, we recognize the interest of -that passage in the Babylonian Genesis tablets which corresponds -with the account in the book of Genesis respecting the -creation of the heavenly bodies. We find in it the earliest -existent record of the origin of astrological superstitions. It -does not express merely the vague belief, which might be -variously interpreted, that the sun and moon and stars were -specially created (after light had been created, after the firmament -had been formed separating the waters above from -the waters below, and after the land had been separated -from the water) to be for signs and for seasons for the inhabitants<span class="pagenum"><a id="Page_393">393</a></span> -of the world—that is, of our earth. It definitely -states that those other suns, the stars, were set into constellation -figures for man’s benefit; the planets and the moon -next formed for his use; and the sun set thereafter in the -heavens as the chief among the celestial bodies.</p> - -<p>It runs thus, so far as the fragments have yet been -gathered together:—</p> - -<p class="p2 center newpage"><span class="smcap">Fifth Tablet of Creation Legend.</span></p> - -<blockquote class="hang2"> - -<p> 1. It was delightful all that was fixed by the great gods.</p> - -<p> 2. Stars, their appearance [in figures] of animals he arranged,</p> - -<p> 3. To fix the year through the observation of their constellations,</p> - -<p> 4. Twelve months (or signs) of stars in three rows he arranged,</p> - -<p> 5. From the day when the year commences unto the close.</p> - -<p> 6. He marked the positions of the wandering stars (planets) to shine -in their courses,</p> - -<p> 7. That they may not do injury, and may not trouble any one.</p> - -<p> 8. The positions of the gods Bel and Hea he fixed with him.</p> - -<p> 9. And he opened the great gates in the darkness shrouded,</p> - -<p>10. The fastenings were strong on the left and right.</p> - -<p>11. In its mass (<i>i.e.</i> the lower chaos) he made a boiling.</p> - -<p>12. The god Uru (the moon) he caused to rise out, the night he over -shadowed,</p> - -<p>13. To fix it also for the light of the night until the shining of the day,</p> - -<p>14. That the month might not be broken, and in its amount be regular.</p> - -<p>15. At the beginning of the month, at the rising of the night,</p> - -<p>16. His horns are breaking through to shine on the heaven.</p> - -<p>17. On the seventh day to a circle he begins to swell,</p> - -<p>18. And stretches towards the dawn further.</p> - -<p>19. When the god Shamas (the sun) in the horizon of heaven, in the -east,</p> - -<p>20. . . . formed beautifully and . . .</p> - -<p>21. . . . . . . to the orbit Shamas was perfected</p> - -<p>22. . . . . . . . . . the dawn Shamas should change</p> - -<p>23. . . . . . . . . . . . . going on its path</p> - -<p>24. . . . . . . . . . . . . . . . giving judgment</p> - -<p>25. . . . . . . . . . . . . . . . . . . to tame</p> - -<p>26. . . . . . . . . . . . . . . . . . . . . . a second time</p> - -<p>27. . . .</p></blockquote> - -<p>Of this tablet Smith remarks that it is a typical specimen -of the style of the series, and shows a marked stage in the<span class="pagenum"><a id="Page_394">394</a></span> -Creation, the appointment of the heavenly orbs running -parallel to the biblical account of the fourth day of Creation. -It is important to notice its significance in this respect. -We can understand now the meaning underlying the words, -“God said, Let there be lights in the firmament of the -heavens, to divide the day from the night; and let them be -for signs and for seasons, and for days and years.” The -order, indeed, in which the bodies are formed according to -the biblical account is inverted. The greater light—the -sun—is made first, to rule the day: then the lesser light—the -moon—to rule the night. These are the heavenly -bodies which in this description rule the day of 24 hours. -The sun may be regarded also as ruling (according to the -ancient view, as according to nature) the seasons and the -year. The stars remain as set in the heaven for signs. -“He made the stars also.” “And God set them”—that is, -the sun, moon, and stars—“in the firmament of the heaven -to give light upon the earth, and to rule over the day and -over the night,” and so forth.</p> - -<p>No one can doubt, I conceive, that the biblical account -is superior to the other, both in a scientific and in a literary -sense. It states much less as actually known, and what it -does state accords better with the facts known in the writer’s -day. Then, the Babylonian narrative, though impressive in -certain passages, is overloaded with detail. In both accounts -we find the heavenly bodies set in the firmament by a -special creative act, and specially designed for the benefit -of man. And in passing I would observe that the discovery -of these Babylonian inscriptions, however they may be -interpreted, and whether they be regarded as somewhat -earlier or somewhat later than the Bible narrative, appears -to dispose finally of the fantastic interpretation assigned by -Hugh Miller and others to the biblical cosmogony, as -corresponding to a series of visions in which the varying -aspects of the world were presented. It has long seemed -to me an utterly untenable proposition that a narrative -seemingly intended to describe definitely a certain series of<span class="pagenum"><a id="Page_395">395</a></span> -events should, after being for ages so interpreted, require now -for its correct interpretation to be regarded as an account of -a series of visions. If the explanation were reconcilable in -any way with the words of Genesis, there yet seems something -of profanity in imagining that men’s minds had thus -been played with by a narrative purporting to be of one -sort yet in reality of quite a different character. But whatever -possibility there may be (and it can be but the barest -possibility) that the Genesis narrative admits of the vision -interpretation, no one can reasonably attempt to extend -that interpretation to the Babylonian account. So that -either a narrative from which the Genesis account was presumably -derived was certainly intended to describe a series -of events, or else a narrative very nearly as early as the -Genesis account, and presumably derived from it at a time -when its true meaning must have been known, presents the -sun, moon, and stars as objects expressly created and set -in the sky after the earth had been formed, and for the -special benefit of man as yet uncreated.</p> - -<p>I am not concerned, however, either to dwell upon this -point, or to insist on any of its consequences. Let us return -to the consideration of the Babylonian narrative as it stands.</p> - -<p>We find twelve constellations or signs of the zodiac are -mentioned as set to fix the year. I am inclined to consider -that the preceding words, “stars, their appearance in figures -of animals he arranged,” relate specially to the stars of the -zodiac. The inventor of this astrogony probably regarded -the stars as originally scattered in an irregular manner over -the heavens,—rather as chaotic material from which constellations -might be formed, than as objects separately and -expressly created. Then they were taken and formed into -figures of animals, set in such a way as to fix the year -through the observation of these constellations. It is hardly -necessary, perhaps, to remind the reader that the word -zodiac is derived from a Greek word signifying an animal, -the original name of the zone being the zodiacal way, or -the pathway of the animals. Our older navigators called it<span class="pagenum"><a id="Page_396">396</a></span> -the Bestiary.<a id="FNanchor_46" href="#Footnote_46" class="fnanchor">46</a> “Twelve months or signs in three rows.” -Smith takes the three rows to mean (i.) the zodiacal signs, -(ii.) the constellations north of the zodiac, and (iii.) the -constellations south of the zodiac. But this does not agree -with the words “twelve signs in three rows.” Possibly the -reference is to three circles, two bounding the zodiac on the -north and south respectively, the third central, the ecliptic, -or track of the sun; or the two tropics and the equator may -have been signified. Instead of “twelve signs in three rows,” -we should, probably, read “twelve signs along a triple band.” -The description was written long after astronomical temples -were first erected, and as the designer of a zodiacal dome -like that (far more recently) erected at Denderah would set -the twelve zodiacal signs along a band formed by three -parallel circles, marking its central line and its northern and -southern limits, so we can understand the writer of the -tablet presenting the celestial architect as working in the -same lines, on a grander scale; setting the twelve zodiacal -signs on the corresponding triple band in the heavens themselves.</p> - -<p>The next point to be noticed in the Babylonian astrology<span class="pagenum"><a id="Page_397">397</a></span> -is the reference to “wandering stars.” Mr. Smith remarks -that the word <i>nibir</i>, thus translated, “is not the usual word -for planet, and there is a star called <i>Nibir</i> near the place -where the sun crossed the boundary between the old and -new years, and this star was one of twelve supposed to -be favourable to Babylonia.” “It is evident,” he proceeds, -“from the opening of the inscription on the first tablet of -the Chaldæan astrology and astronomy, that the functions -of the stars were, according to the Babylonians, to act not -only as regulators of the seasons and the year, but also to -be used as signs, as in Genesis i. 14; for in those ages it -was generally believed that the heavenly bodies gave, by -their appearance and positions, signs of events which were -coming on the earth.” The two verses relating to Nibir -seem to correspond to no other celestial bodies but planets -(unless, perhaps, to comets). If we regard Nibir as signifying -any fixed star, we can find no significance in the marking -of the course of the star Nibir, that it may do no injury -and may not trouble any one. Moreover, as the fixed stars, -the sun, and the moon, are separately described, it seems -unlikely that the planets would be left unnoticed. In the -biblical narrative the reference to the celestial bodies is so -short that we can understand the planets being included in -the words, “He made the stars also.” But in an account -so full of detail as that presented in the Babylonian tablet, -the omission of the planets would be very remarkable. It -is also worthy of notice that in Polyhistor’s Babylonian -traditions, recorded by Berosus, we read that “Belus formed -the stars, the sun, the moon, and the five planets.”</p> - -<p>In the tablet narrative the creator of the heavenly bodies -is supposed to be Anu, god of the heavens. This is inferred -by Mr. Smith from the fact “that the God who created the -stars, fixed places or habitations for Bel and Hea with himself -in the heavens.” For according to the Babylonian -theogony, the three gods Anu, Bel, and Hea share between -them the divisions of the face of the sky.</p> - -<p>The account of the creation of the moon is perhaps the<span class="pagenum"><a id="Page_398">398</a></span> -most interesting part of the narrative. We see that, according -to the Babylonian philosophy, the earth is regarded as -formed from the waters and resting after its creation above -a vast abyss of chaotic water. We find traces of this old -hypothesis in several biblical passages, as, for instance, in -the words of the Third Commandment, “the heaven above, -the earth beneath, and the waters under the earth;” and -again in Proverbs xxx. 4, “Who hath bound the waters in -a garment? who hath established all the ends of the earth?” -“The great gates in the darkness shrouded, the fastenings -strong on the left and right,” in the Babylonian account, -refer to the enclosure of the great infernal lake, so that the -waters under the earth might not overwhelm the world. It -is from out the dark ocean beneath the earth that the god -Anu calls the moon into being. He opens the mighty gates -shrouded in the nether darkness, and creates a vast whirlpool -in the gloomy ocean; then “at his bidding, from the -turmoil arose the moon like a giant bubble, and passing -through the open gates mounted on its destined way across -the vaults of heaven.” It is strange to reflect that in quite -recent times, at least 4000 years after the Babylonian tablet -was written, and who shall tell how many years after the -tradition was first invented?—a theory of the moon’s origin -not unlike the Babylonian hypothesis has been advanced, -despite overwhelming dynamical objections; and a modern -paradoxist has even pointed to the spot beneath the ocean -where a sudden increase of depth indicates that matter was -suddenly extruded long ago, and driven forcibly away from -the earth to the orbit along which that expelled mass—our -moon—is now travelling.</p> - -<p>It would have been interesting to have known how the -Babylonian tablet described the creation of Shamas, the -sun; though, so far as can be judged from the fragments -above quoted, there was not the same fulness of detail in -this part of the description as in that relating to the moon. -Mr. Smith infers that the Babylonians considered the moon -the more important body, unlike the writer or compiler of<span class="pagenum"><a id="Page_399">399</a></span> -the book of Genesis, who describes the sun as the greater -light. It does not seem to follow very clearly, however, -from the tablet record, that the sun was considered inferior -to the moon in importance, and certainly we cannot imagine -that the Babylonians considered the moon a greater light. -The creation of the stars precedes that of the moon, though -manifestly the moon was judged to be more important than -the stars. Not improbably, therefore, the sun, though -following the moon in order of creation, was regarded as -the more important orb of the two. In fact, in the Babylonian -as in the (so-called) Mosaic legend of Creation, the -more important members of a series of created bodies are, -in some cases, created last—man last of all orders of animated -beings, for instance.</p> - -<p>If we turn now from the consideration of the Babylonian -tradition of the creation of the heavenly bodies to note how -the biblical account differs from it, not only or chiefly in -details, but in general character, we seem to recognize in -the latter a determination to detach from the celestial orbs -the individuality, so to speak, which the older tradition had -given to them. The account in Genesis is not only simpler, -and, in a literary sense, more effective, but it is in another -sense purified. The celestial bodies do not appear in it as -celestial beings. The Babylonian legend is followed only so -far as it can be followed consistently with the avoidance of -all that might tempt to the worship of the sun, moon, and -stars. The writer of the book of Genesis, whether Moses -or not, seems certainly to have shared the views of Moses as -to the Sabæanism of the nation from which the children of -Abraham had separated. Moses warned the Israelite,—“Take -good heed unto thyself, lest thou lift up thine eyes -unto heaven; and when thou seest the sun, and the moon, -and the stars, even all the host of heaven, shouldest be -driven to worship them, and serve them, which the Lord thy -God hath divided unto all nations under the whole heaven.” -So the writer of Genesis is careful to remove from the tradition -which he follows all that might suggest the individual<span class="pagenum"><a id="Page_400">400</a></span> -power and influence of the heavenly bodies. The stars are -to be for signs, but we read nothing of the power of the -wandering stars “to do injury or trouble any one.” (That is, -not in the book of Genesis. In the song of Deborah we -find, though perhaps only in a poetic fashion, the old influences -assigned to the planets, when the singer says that -the “stars in their courses fought against Sisera.” Deborah, -however, was a woman, and women have always been loth -and late to give up ancient superstitions.) Again, the sun -and the moon in Genesis are the greater and the lesser -lights, not, as in the Babylonian narrative, the god Shamas -and the god Uru.</p> - -<p>We may find a parallel to this treatment of the Babylonian -myth in the treatment by Moses of the observance of -the Sabbath, a day of rest which the Babylonian tablets show -to have had, as for other reasons had been before suspected, -an astrological significance. The Jewish lawgiver does not -do away with the observance; in fact, he was probably -powerless to do away with it. At any rate, he suffers the -observance to remain, precisely as the writer of the book of -Genesis retains the Babylonian tradition of the creation of -the celestial bodies. But he is careful to expurgate the -Chaldæan observance, just as the writer of Genesis is careful -to expurgate the Babylonian tradition. The week as a -period is no longer associated with astrological superstitions, -nor the Sabbath rest enjoined as a fetish. Both ideas are -directly associated with the monotheistic principle which -primarily led to the separation of the family of Abraham -from the rest of the Chaldæan race. In Babylonia, the -method of associating the names of the sun, moon, and stars -with the days, doubtless had its origin. Saturn was the -Sabbath star, as it is still called (Sabbatai) in the Talmud. -But, as Professor Tischendorf told Humboldt, in answer to -a question specially addressed to him on the subject, “there -is an entire absence in both the Old and New Testaments, -of any traces of names of week-days taken from the planets.” -The lunar festivals, again, though unquestionably Sabaistic<span class="pagenum"><a id="Page_401">401</a></span> -in their origin, were apparently too thoroughly established -to be discarded by Moses; nay, he was even obliged to -permit the continuance of many observances which suspiciously -resembled the old offerings of sacrifice to the moon as -a deity. He had also to continue the sacrifice of the passover, -the origin of which was unmistakably astronomical,—corresponding -in time to the sun’s passage across the -equator, or rather to the first lunar month following and -including that event. But he carefully dissociates both the -lunar and the lunisolar sacrifices from their primary Sabaistic -significance. In fact, the history of early Hebrew legislation, -so far as it related to religion, is the history of a struggle -on the part of the lawgivers and the leaders of opinion against -the tendency of the people to revert to the idolatrous worship -of their ancestors and of races closely akin to them—especially -against the tendency to the worship of the sun and moon -and all the host of heaven.</p> - -<p>In the very fact, however, that this contest was maintained, -while yet the Hebrew cosmogony, and in particular -the Hebrew astrogony, contains indubitable evidence of its -origin in the poetical myths of older Babylonia, we find one -of the strongest proofs of the influence which the literature -of Babylon, when at the fulness of its development, exerted -upon surrounding nations. This influence is not more -clearly shown even by the fact that nearly 2000 years after -the decay of Babylonian literature, science, and art, a nation -like the Assyrians, engaged in establishing empire rather -than in literary and scientific pursuits, should have been at -the pains to obtain copies of many thousands of the tablet -records which formed the libraries of older Babylonia. In -both circumstances we find good reason for hoping that -careful search among Assyrian and Babylonian ruins may -not only be rewarded by the discovery of many other portions -of the later Assyrian library (which was also in some sense a -museum), but that other and earlier copies of the original -Babylonian records may be obtained. For it seems unlikely -that works so valuable as to be thought worth recopying after<span class="pagenum"><a id="Page_402">402</a></span> -1500 or 2000 years, in Assyria, had not been more than -once copied during the interval in Babylonia. “Search in -Babylonia,” says Mr. Smith, “would no doubt yield earlier -copies of all these works, but that search has not yet been -instituted, and for the present we have to be contented with -our Assyrian copies. Looking, however, at the world-wide -interest of the subjects, and at the important evidence which -perfect copies of these works would undoubtedly give, there -can be no doubt,” Mr. Smith adds, “that the subject of -further search and discovery will not slumber, and that all as -yet known will one day be superseded by newer texts and -fuller and more perfect light.”</p> - -<p class="p4 center smaller vspace"> -Printed by <span class="smcap">Ballantyne, Hanson & Co.</span><br /> -Edinburgh & London -</p> - -<div class="chapter"><div class="footnotes"> -<h2 class="nobreak p1"><a id="FOOTNOTES"></a>FOOTNOTES</h2> - -<div class="footnote"> - -<p class="fn1"><a id="Footnote_1" href="#FNanchor_1" class="fnanchor">1</a> More strictly, it plays the same part as a glass screen before a -glowing fire. When the heat of the fire falls on such a screen (through -which light passes readily enough), it is received by the glass, warming -the glass up to a certain point, and the warmed glass emits in all directions -the heat so received; thus scattering over a large space the rays -which, but for the glass, would have fallen directly upon the objects -which the screen is intended to protect.</p></div> - -<div class="footnote"> - -<p class="fn1"><a id="Footnote_2" href="#FNanchor_2" class="fnanchor">2</a> The case here imagined is not entirely hypothetical. We examine -Mercury and Venus very nearly under the conditions here imagined; -for we can obtain only spectroscopic evidence respecting the existence of -water on either planet. In the case of Mars we have telescopic evidence, -and no one now doubts that the greenish parts of the planet are seas -and oceans. But Venus and Mercury are never seen under conditions -enabling the observer to determine the colour of various parts of their -discs. -</p> -<p> -I may add that a mistake, somewhat analogous to that which I have -described in the cases of an imagined observer of our earth, has been -made by some spectroscopists in the case of the planets Jupiter and -Saturn. In considering the spectroscopic evidence respecting the condition -of these planets’ atmospheres, they have overlooked the circumstance -that we can judge only of the condition of the outermost and -coolest layers, for the lower layers are concealed from view by the -enormous cloud masses, floating, as the telescope shows, in the atmospheric -envelopes of the giant planets. Thus the German spectroscopist -Vögel argues that because in the spectrum of Jupiter dark lines are seen -which are known to belong to the absorption-spectrum of aqueous -vapour, the planet’s surface cannot be intensely hot. But Jupiter’s -absorption-spectrum belongs to layers of his atmosphere lying far above -his surface. We can no more infer the actual temperature of Jupiter’s -surface from the temperature of the layers which produce his absorption-spectrum, -than a visitor who should view our earth from outer space, -observing the low temperature of the air ten or twelve miles above the -sea-level, could infer thence the actual temperature of the earth’s surface.</p></div> - -<div class="footnote"> - -<p class="fn1"><a id="Footnote_3" href="#FNanchor_3" class="fnanchor">3</a> In “Other Worlds than Ours,” I wrote as follows:—“The lines -of hydrogen, which are so well marked in the solar spectrum, are not -seen in the spectrum of Betelgeux. We are not to conclude from this -that hydrogen does not exist in the composition of the star. We know -that certain parts of the solar disc, when examined with the spectroscope, -do not at all times exhibit the hydrogen lines, or may even present them -as bright instead of dark lines. It may well be that in Betelgeux -hydrogen exists under such conditions that the amount of light it sends -forth is nearly equivalent to the amount it absorbs, in which case its -characteristic lines would not be easily discernible. In fact, it is important -to notice generally, that while there can be no mistaking the -positive evidence afforded by the spectroscope as to the existence of -any element in sun or star, the negative evidence supplied by the absence -of particular lines is not to be certainly relied upon.”</p></div> - -<div class="footnote"> - -<p class="fn1"><a id="Footnote_4" href="#FNanchor_4" class="fnanchor">4</a> Dr. Draper remarks here in passing, “I do not think that, in -comparisons of the spectra of the elements and sun, enough stress has -been laid on the general appearance of lines apart from their mere -position; in photographic representations this point is very prominent.”</p></div> - -<div class="footnote"> - -<p class="fn1"><a id="Footnote_5" href="#FNanchor_5" class="fnanchor">5</a> The word “ignited” may mislead, and indeed is not correctly -used here. The oxygen in the solar atmosphere, like the hydrogen, is -simply glowing with intensity of heat. No process of combustion is -taking place. Ignition, strictly speaking, means the initiation of the -process of combustion, and a substance can only be said to be ignited -when it has been set burning. The word <em>glowing</em> is preferable; or if -reference is made to heat and light combined, then “glowing with intensity -of heat” seems the description most likely to be correctly understood.</p></div> - -<div class="footnote"> - -<p class="fn1"><a id="Footnote_6" href="#FNanchor_6" class="fnanchor">6</a> It would be an interesting experiment, which I would specially -recommend to those who, like Dr. Draper, possess instrumental means -specially adapted to the inquiry, to ascertain what variations, if any, -occur in the solar spectrum when (i.) the central part of the disc alone, -and (ii.) the outer part alone, is allowed to transmit light to the spectroscope. -The inquiry seems specially suited to the methods of spectral -photography pursued by Dr. Draper, and by Dr. Huggins, in this -country. Still, I believe interesting results can be obtained even without -these special appliances; and I hope before long to employ my own -telescope in this department of research.</p></div> - -<div class="footnote"> - -<p class="fn1"><a id="Footnote_7" href="#FNanchor_7" class="fnanchor">7</a> In 1860, a year of maximum sun-spot frequency, Cambridge won -the University boat-race; the year 1865, of minimum sun-spot frequency, -marked the middle of a long array of Oxford victories; 1872, the next -maximum, marked the middle of a Cambridge series of victories. May -we not anticipate that in 1878, the year of minimum spot frequency, -Oxford will win? [This prediction made in autumn, 1877, was fulfilled.] -I doubt not similar evidence might be obtained about cricket.</p></div> - -<div class="footnote"> - -<p class="fn1"><a id="Footnote_8" href="#FNanchor_8" class="fnanchor">8</a> It must be understood that this remark relates only to the theory -that by close scrutiny of the sun a power of predicting weather peculiarities -can be obtained, not to the theory that there may be a cyclic -association between sun-spots and the weather. If this association -exists, yet no scrutiny of the sun can tell us more than we already know, -and it will scarcely be pretended that new solar observatories could -give us any better general idea of the progress of the great sun-spot -period than we obtain from observatories already in existence, or, -indeed, might obtain from the observations of a single amateur telescopist. -</p> -<p> -I think it quite possible that, from the systematic study of terrestrial -relations, the existence of a cyclic association between the great spot -period and terrestrial phenomena may be demonstrated, instead of being -merely surmised, as at present. By the way, it may be worth noting -that a prediction relative to the coming winter [that of 1877–78] has -been made on the faith of such association by Professor Piazzi Smyth. -It runs as follows:— -</p> -<p> -“Having recently computed the remaining observations of our -earth-thermometers here, and prepared a new projection of all the observations -from their beginning in 1837 to their calamitous close last -year [1876]—results generally confirmatory of those arrived at in 1870 -have been obtained, but with more pointed and immediate bearing on -the weather now before us. -</p> -<p> -“The chief features undoubtedly deducible for the past thirty-nine -years, after eliminating the more seasonal effects of ordinary summer -and winter, are:— -</p> -<p> -“1. Between 1837 and 1876 three great heat-waves, from without, -struck this part of the earth, viz., the first in 1846·5, the second in -1858·0, and the third in 1868·7. And unless some very complete alteration -in the weather is to take place, the next such visitation may be -looked for in 1879·5, within limits of half a year each way. -</p> -<p> -“2. The next feature in magnitude and certainty is that the periods -of minimum temperature, or cold, are not either in, or anywhere near, -the middle time between the crests of those three chronologically -identified heat-waves, but are comparatively close up to them <em>on either -side</em>, at a distance of about a year and a half, so that the next such cold-wave -is due at the end of the present year [1877]. -</p> -<p> -“This is, perhaps, not an agreeable prospect, especially if political -agitators are at this time moving amongst the colliers, striving to persuade -them to decrease the out-put of coal at every pit’s mouth. Being, -therefore, quite willing, for the general good, to suppose myself mistaken, -I beg to send you a first impression of plate 17 of the forthcoming -volume of observations of this Royal Observatory, and shall be -very happy if you can bring out from the measures recorded there any -more comfortable view for the public at large. -</p> -<p class="sigright"> -<span class="l4">“<span class="smcap">Piazzi Smyth</span>,</span><br /> -“Astronomer-Royal for Scotland.” -</p> -<p> -If this prediction shall be confirmed [this was written in autumn, -1877], it will afford an argument in favour of the existence of the cyclic -relation suggested, but no argument for the endowment of solar research. -Professor Smyth’s observations were not solar but terrestrial. -</p> -<p> -[The prediction was not confirmed, the winter of 1877–78 being, on -the contrary, exceptionally mild.]</p></div> - -<div class="footnote"> - -<p class="fn1"><a id="Footnote_9" href="#FNanchor_9" class="fnanchor">9</a> The reader unfamiliar with the principles of the telescope may -require to be told that in the ordinary telescope each part of the object-glass -forms a complete image of the object examined. If, when using -an opera-glass (one barrel), a portion of the large glass be covered, a -portion of what had before been visible is concealed. But this is not -the case with a telescope of the ordinary construction. All that happens -when a portion of the object-glass is covered is that the object appears -in some degree less fully illuminated.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_10" href="#FNanchor_10" class="fnanchor">10</a> It may be briefly sketched, perhaps, in a note. The force necessary -to draw the earth inwards in such sort as to make her follow her -actual course is proportional to (i) the square of her velocity directly, -and (ii) her distance from the sun inversely. If we increase our estimate -of the earth’s distance from the sun, we, in the same degree, -increase our estimate of her orbital velocity. The square of this velocity -then increases as the square of the estimated distance; and therefore, -the estimated force sunwards is increased as the square of the distance -on account of (i), and diminished as the distance on account of (ii), and -is, therefore, on the whole, increased as the distance. That is, we now -regard the sun’s action as greater at this greater distance, and in the -same degree that the distance is greater; whereas, if it had been what -we before supposed it, it would be less at the greater distance as the -square of the distance (attraction varying inversely as the square of the -distance). Being greater as the distance, instead of less as the square -of the distance, it follows that our estimate of the sun’s absolute force is -now greater as the cube of the distance. Similarly, if we had diminished -our estimate of the sun’s distance, we should have diminished our estimate -of his absolute power (or mass) as the cube of the distance. But -our estimate of the sun’s volume is also proportional to the cube of his -estimated distance. Hence our estimate of his mass varies as our -estimate of his volume; or, our estimate of his mean density is constant.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_11" href="#FNanchor_11" class="fnanchor">11</a> Only very recently an asteroid, Hilda (153rd in order of detection), -has been discovered which travels very much nearer to the path of -Jupiter than to that of Mars—a solitary instance in that respect. Its -distance (the earth’s distance being represented by unity), is 3·95, -Jupiter’s being 5·20, and Mars’s 1·52; its period falls short of 8 years -by only two months, the average period of the asteroidal family being -only about 4½ years. Five others, Cybele, Freia, Sylvia, Camilla, and -Hermione, travel rather nearer to Jupiter than to Mars; but the remaining -166 travel nearer to Mars, and most of them much nearer.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_12" href="#FNanchor_12" class="fnanchor">12</a> Even this statement is not mathematically exact. If the rails are -straight and parallel, the ratio of approach and recession of an engine -on one line, towards or from an engine on the other, is never quite -equal to the engines’ velocities added together; but the difference -amounts practically to nothing, except when the engines are near each -other.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_13" href="#FNanchor_13" class="fnanchor">13</a> I have omitted all reference to details; but in reality the double -battery was automatic, the motion of the observing telescope, as -different colours of the spectrum were brought into view, setting all the -prisms of the double battery into that precise position which causes them -to show best each particular part of the spectrum thus brought into -view. It is rather singular that the first view I ever had of the solar -prominences, was obtained (at Dr. Huggins’s observatory) with this -instrument of my own invention, which also was the first powerful -spectroscope I had ever used or even seen.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_14" href="#FNanchor_14" class="fnanchor">14</a> It varies more in some months than in others, as the moon’s orbit -changes in shape under the various perturbing influences to which she is -subject.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_15" href="#FNanchor_15" class="fnanchor">15</a> It may seem strange to say that one hundred and twenty years after -the passage of a comet which last passed in 1862, and was then first -discovered, August meteors have been seen. But in reality, as we know -the period of that comet to be about one hundred and thirty years, we -know that the displays of the years 1840, 1841, etc., to 1850, must -have followed the preceding passage by about that interval of time.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_16" href="#FNanchor_16" class="fnanchor">16</a> The D line, properly speaking, as originally named by Fraunhofer, -belongs to sodium. The line spoken of above as the sierra -D line is one close by the sodium line, and mistaken for it when -first seen in the spectrum of the coloured prominences as a bright -line. It does not appear as a dark line in the solar spectrum.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_17" href="#FNanchor_17" class="fnanchor">17</a> Since this was written, I have learned that Mr. Backhouse, of -Sunderland, announced similar results to those obtained at Dunecht, as -seen a fortnight or so earlier.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_18" href="#FNanchor_18" class="fnanchor">18</a> Here no account is taken of the motions of the stars within the -system; such motions must ordinarily be minute compared with the -common motion of the system.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_19" href="#FNanchor_19" class="fnanchor">19</a> Eight pictures of nebulæ were exhibited in illustration of this -peculiarity.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_20" href="#FNanchor_20" class="fnanchor">20</a> Sir John Herschel long since pointed to the variation of our sun as -a possible cause of such changes of terrestrial climate.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_21" href="#FNanchor_21" class="fnanchor">21</a> During these journeys the Atlantic was sounded, and Scoresby’s -estimate of the enormous depth of the Atlantic to the north-west of -Spitzbergen was fully confirmed, the line indicating a depth of more -than two miles. It was found also that Spitzbergen is connected with -Norway by a submarine bank.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_22" href="#FNanchor_22" class="fnanchor">22</a> It is far from improbable that a change has taken place in the -climate of the part of the Arctic regions traversed by Koldewey; for -the Dutch seem readily to have found their way much further north two -centuries ago. Indeed, among Captain Koldewey’s results is one which -seems to indicate the occurrence of such a change. The country he -explored was found to have been inhabited. “Numerous huts of -Esquimaux were seen, and various instruments and utensils of primitive -form; but for some reason or other the region seems to have been finally -deserted. The Polar bear reigns supreme on the glaciers, as the walrus -does among the icebergs.” Not improbably the former inhabitants were -forced to leave this region by the gradually increasing cold.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_23" href="#FNanchor_23" class="fnanchor">23</a> Dr. Emile Bessels was tried at New York in 1872, on the charge -of having poisoned Captain Hall, but was acquitted.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_24" href="#FNanchor_24" class="fnanchor">24</a> The phenomena here described are well worth observing on their -own account, as affording a very instructive and at the same time very -beautiful illustration of wave motions. They can be well seen at many -of our watering-places. The same laws of wave motion can be readily -illustrated also by throwing two stones into a large smooth pool, at -points a few yards apart. The crossing of the two sets of circular waves -produces a wave-net, the meshes of which vary in shape according to their -position.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_25" href="#FNanchor_25" class="fnanchor">25</a> It is a pity that men of science so often forget, when addressing -those who are not men of science, or who study other departments than -theirs, that technical terms are out of place. Most people, I take it -are more familiar, on the whole, with eyelids than with <i xml:lang="la" lang="la">palpebræ</i>.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_26" href="#FNanchor_26" class="fnanchor">26</a> This nautical expression is new to me. Top-gallants—fore, main, -and mizen—I know, and forecastle I know, but the top-gallant forecastle -I do not know.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_27" href="#FNanchor_27" class="fnanchor">27</a> The instrument was lent to Mr. Huggins by Mr. W. Spottiswoode. -It has been recently employed successfully at Greenwich.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_28" href="#FNanchor_28" class="fnanchor">28</a> Thus in <cite>Christie Johnstone</cite>, written in 1853, when Flucker Johnstone -tells Christie the story of the widow’s sorrows, giving it word for -word, and even throwing in what dramatists call “the business,” he -says, “‘Here ye’ll play your hand like a geraffe.’ ‘Geraffe?’ she -says; ‘that’s a beast, I’m thinking.’ ‘Na; it’s the thing on the hill -that makes signals.’ ‘Telegraph, ye fulish goloshen!’ ‘Oo, ay, telegraph! -geraffe’s sunnest said for a’.’” “Playing the hand like a -telegraph” would now be as unmeaning as Flucker Johnstone’s original -description.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_29" href="#FNanchor_29" class="fnanchor">29</a> Not “to represent the gutta-percha,” as stated in the <cite>Times</cite> -account of Mr. Muirhead’s invention. The gutta-percha corresponds -to the insulating material of the artificial circuit; viz., the prepared -paper through which the current along the tinfoil strips acts inductively -on the coating of tinfoil.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_30" href="#FNanchor_30" class="fnanchor">30</a> I must caution the reader against Fig. 348 in Guillemin’s <cite>Application -of the Physical Forces</cite>, in which the part <i>c d</i> of the wire is not shown. -The two coils are in reality part of a single coil, divided into two to -permit of the bar being bent; and to remove the part <i>c d</i> is to divide -the wire, and, of course, break the current. It will be seen that <i>c d</i> -passes from the remote side of coil <i>b c</i>, <a href="#ip_253">Fig. 6</a>, to the near side of coil <i>d e</i>. -If it were taken round the remote side of the latter coil, the current -along this would neutralize the effect of the current along the other.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_31" href="#FNanchor_31" class="fnanchor">31</a> The paper is soaked in dilute ferrocyanide of potassium, and the -passage of the current forms a Prussian blue.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_32" href="#FNanchor_32" class="fnanchor">32</a> Sir W. Thomson states, in his altogether excellent article on the -electric telegraph, in Nichol’s <cite>Cyclopædia</cite>, that the invention of this -process is due to Mr. Bakewell.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_33" href="#FNanchor_33" class="fnanchor">33</a> It is to be noticed, however, that the recording pointer must -always mark its lines in the same direction, so that, unless a message is -being transmitted at the same time that one is being received (in which -case the oscillations both ways are utilized), the instrument works only -during one-half of each complete double oscillation.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_34" href="#FNanchor_34" class="fnanchor">34</a> It seems to me a pity that in the English edition of this work the -usual measures have not been substituted throughout. The book is not -intended or indeed suitable for scientific readers, who alone are accustomed -to the metric system. Other readers do not care to have a little -sum in reduction to go through at each numerical statement.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_35" href="#FNanchor_35" class="fnanchor">35</a> Hanno’s <cite>Periplus</cite>—the voyage of Hanno, chief of the Carthaginians, -round the parts of Libya, beyond the Pillars of Hercules, the -narrative of which he posted up in the Temple of Kronos.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_36" href="#FNanchor_36" class="fnanchor">36</a> I may mention one which occurred within my own experience. -A mastiff of mine, some years ago, was eating from a plate full of broken -meat. It was his custom to bury the large pieces when there was more -than he could get through. While he was burying a large piece, a cat -ran off with a small fragment. The moment he returned to the plate he -missed this, and, seeing no one else near the plate, he, in his own way, -accused a little daughter of mine (some two or three years old) of the -theft. Looking fiercely at her, he growled his suspicions, and would not -suffer her to escape from the corner where his plate stood until I dragged -him away by his chain. Nor did he for some time forget the wrong -which he supposed she had done him, but always growled when she -came near his house.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_37" href="#FNanchor_37" class="fnanchor">37</a> It may be suggested, in passing, that the association which has -been commonly noticed between prominent eyeballs and command of -language (phrenologists place the organ of language, in their unscientific -phraseology, behind the eyeballs) may be related in some degree to the -circumstance that in gradually emerging from the condition of an arboreal -creature the anthropoid ape would not only cease to derive advantage -from sunken eyes, but would be benefited by the possession of more -prominent eyeballs. The increasing prominence of the eyeballs would -thus be a change directly associated with the gradual advance of the -animal to a condition in which, associating into larger and larger companies -and becoming more and more dependent on mutual assistance -and discipline, they would require the use of a gradually extending -series of vocal signs to indicate their wants and wishes to each other.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_38" href="#FNanchor_38" class="fnanchor">38</a> The word hypothesis is too often used as though it were synonymous -with theory, so that Newton’s famous saying, “Hypotheses non -fingo” has come to be regarded by many as though it expressed an -objection on Newton’s part against the formation of theories. This -would have been strange indeed in the author of the noblest theory yet -propounded by man in matters scientific. Newton indicates his meaning -plainly enough, in the very paragraph in which the above expression -occurs, defining an hypothesis as an opinion not based on phenomena.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_39" href="#FNanchor_39" class="fnanchor">39</a> I find it somewhat difficult to understand clearly Mr. Mivart’s -own position with reference to the general theory of evolution. He -certainly is an evolutionist, and as certainly he considers natural selection -combined with the tendency to variation (as ordinarily understood) -insufficient to account for the existence of the various forms of animal -and vegetable existence. He supplies the missing factor in “an innate -law imposed on nature, by which new and definite species, under -definite conditions, emerged from a latent and potential being into -actual and manifest existence;” and, so far as can be judged, he considers -that the origin of man himself is an instance of the operation of -this law.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_40" href="#FNanchor_40" class="fnanchor">40</a> The Middle Tertiary period—the Tertiary, which includes the -Eocene, Miocene, and Pliocene periods, being the latest of the three -great periods recognized by geologists as preceding the present era, -which includes the entire history of man as at present known geologically.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_41" href="#FNanchor_41" class="fnanchor">41</a> Closely following in this respect his illustrious namesake Roger, -who writes, in the sixth chapter of his <cite>Opus Majus</cite>, “<cite>Sine experientia -nihil sufficienter sciri potest.</cite>”</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_42" href="#FNanchor_42" class="fnanchor">42</a> Fibrine and albumen are identical in composition. <em>Caseine</em>, -which is the coagulable portion of milk, is composed in the same manner. -The chief distinction between the three substances consists in -their mode of coagulation; fibrine coagulating spontaneously, albumen -under the action of heat, and caseine by the action of acetic acid.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_43" href="#FNanchor_43" class="fnanchor">43</a> To this article of the Professor’s faith decided objection must be -taken, however.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_44" href="#FNanchor_44" class="fnanchor">44</a> Those whose custom it is to regard all theorizing respecting the -circumstances revealed by observation as unscientific, may read with -profit an extremely speculative passage in Newton’s <cite>Principia</cite> relating -to the probable drying up of the earth in future ages. “As the seas,” -he says, “are absolutely necessary to the constitution of our earth, -that from them the sun, by its heat, may exhale a sufficient quantity of -vapours, which, being gathered together into clouds, may drop down in -rain, for watering of the earth, and for the production and nourishment -of vegetables; or being condensed with cold on the tops of mountains -(as some philosophers with reason judge), may run down in springs -and rivers; so for the conservation of the seas and fluids of the planets, -comets seem to be required, that, from their exhalations and vapours -condensed, the wastes of the planetary fluids spent upon vegetation -and putrefaction, and converted into dry earth, may be ultimately -supplied and made up; for all vegetables entirely derive their growths -from fluids, and afterwards, in great measure, are turned into dry earth -by putrefaction; and a sort of slime is always found to settle at the -bottom of putrefied fluids; and hence it is that the bulk of the solid -earth is continually increased; and the fluids, if they are not supplied -from without, must be in a continual decrease, and quite fail at last. -I suspect, moreover, that it is chiefly from the comets that spirit comes -which is indeed the smallest but the most subtle and useful part of our -air, and so much required to sustain the life of all things with us.”</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_45" href="#FNanchor_45" class="fnanchor">45</a> See my “Science Byways,” pp. 244, 245.</p></div> - -<div class="footnote"> - -<p class="fn2"><a id="Footnote_46" href="#FNanchor_46" class="fnanchor">46</a> The following passage from Admiral Smyth’s Bedford Catalogue -is worth noticing in this connection:—“We find that both the Chinese -and the Japanese had a zodiac consisting of animals, as <em>zodiacs</em> needs -must, among which they placed a tiger, a peacock, a cat, an alligator, -a duck, an ape, a hog, a rat, and what not. Animals also formed the -<i xml:lang="la" lang="la">Via Solis</i> of the Kirghis, the Mongols, the Persians, the Mantshus, and -the ancient Turks; and the Spanish monks in the army of Cortes found -that the Mexicans had a zodiac with strange creatures in the departments. -Such a striking similitude is assuredly indicative of a common -origin, since the coincidences are too exact in most instances to be the -effect of chance; but where this origin is to be fixed has been the -subject of interminable discussions, and learning, ignorance, sagacity, -and prejudice have long been in battle array against each other. -Diodorus Siculus considers it to be Babylonian, but Bishop Warburton, -somewhat dogmatically tells us, ‘Brute worship gave rise to the -Egyptian asterisms prior to the time of Moses.’” There is now, of -course, very little reason for questioning that Egyptian astronomy was -borrowed from Babylon.</p></div> -</div></div> - -<div class="chapter"><div class="transnote"> -<h2 class="nobreak p1"><a id="Transcribers_Notes"></a>Transcriber’s Notes</h2> - -<p>Cover created by Transcriber and placed in the Public Domain.</p> - -<p>Punctuation, hyphenation, and spelling were made consistent when a predominant -preference was found in this book; otherwise they were not changed.</p> - -<p>Simple typographical errors were corrected; occasional unbalanced -quotation marks retained.</p> - -<p>Ambiguous hyphens at the ends of lines were retained.</p> - -<p>Some ditto marks have been replaced by the actual text.</p> - -<p>Page <a href="#ip_83">83</a>: In the illustration, “O” should be “C”.</p> - -<p>Page <a href="#Page_171">171</a>: There is no obvious closing quotation mark to match -the opening mark at “of most unusual age and thickness”.</p> - -<p>Page <a href="#Page_192">192</a>: “Divided even between the ocean” may be a misprint -for “evenly”.</p> - -<p>Page <a href="#Page_197">197</a>: No matching closing quotation mark for the opening -mark at “the small bright spot”.</p> - -<p>Page <a href="#Page_222">222</a>: Transcriber added an opening quotation mark at -“Down his back” to match the closing mark after -“He was seen by every one on board.”</p> - -<p>Page <a href="#Page_230">230</a>: No matching closing quotation mark for the opening -mark at “a whale of large size”.</p> - -<p>Page <a href="#Page_302">302</a>: Transcriber added an opening quotation mark at -“About fifty years ago” to match the closing mark after -“fed himself with the other.”</p> - -<p>Page <a href="#Page_372">372</a>: No matching opening quotation mark for the closing -mark after “its lower extremity.”</p> - -<p>Page <a href="#Page_385">385</a>: No matching closing quotation mark for the opening -mark at “sweeps off from”.</p> -</div></div> - - - - - - - - -<pre> - - - - - -End of Project Gutenberg's Pleasant Ways in Science, by Richard A. 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