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-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
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-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 ***
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-Produced by Chris Curnow, Charlie Howard, and the Online
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-file was produced from images generously made available
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-
-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. Proctor
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