Other worlds than ours; the plurality of worlds studied under the light of recent scientific researches

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'A^^jAAyI yfettpMi i^

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Preface

The general purpose I have had in view in writing the present treatise will be gathered from the introductory pages; but I wish to offer here a few remarks on certain points of detail.

It will be seen that, on many of the subjects dealt with in this work, I have propounded views which differ from those usually accepted. I have not done this from any love of novelty, nor from any desire to attract attention by hizarre or fanciful theories. Each of the new views here presented has been the result of a careful study of the subject dealt with, and I have searched as anxiously for considerations opposed to any novel theory as for arguments in its favor. If others should be more successful than I have been in finding reasons for rejecting any of my views, I shall be ready to abandon them without regret. I trust I am free from that weakness which forces a man to regard every theory he has once advocated as a matter to be defended at all hazards. ]S r o weakness more mischievously affects the work of the student of science. As Faraday said, " Truth should be the primary object of the philosopher ; " and this can never be the case if, where he imagines he holds a theory, the theory has in truth possession of him.

Some among my readers will recognize, in the views here presented, the growth of ideas which 1 have dealt with consecutively, with more or less fulness, in the pages of several quarterly, monthly, and weekly serials, and in one of our leading daily newspapers. I refer to this, because it has happened to me several times lately to be accused of plagiarism, when I have had occasion, in developing fresh ideas on a subject, to repeat statements which (unknown of course to my accusers) had proceeded from mj own pen. It is not often one is accused of stealing one's own ideas, but that is a pleasure I have more than once been enabled to enjoy of late, and I here present my compliments to those who (anonymously or otherwise) have afforded me that luxury.

Wherever it has been in accordance with the custom of any journal, however, I have always written under my own name.

Since the manuscript of this work was placed id the printers' hands, I have obtained fresh evidence on some ol the theories dealt with in the following pages.

One of the most surprising phenomena ever witnessed by the telescopist — a phenomenon I had read of lono; since, but had not thought of in connection with my subject — seems to me to afford stronger evidence than any adduced in the text, in favor of my theory that the major planets are subsidiary suns supplying heat (if not a minute proportion of light even) to their satellites. I refer to the observation made by Admiral Smyth, that on one occasion the second satellite of Jupiter, twelve minutes after entering on the disk of the planet, was seen outside the limb, "where it remained four minutes, and then suddenly vanished." Two other equally competent observers, Maclear and Pearson, witnessed the same phenomenon. " Here," says "Webb, " explanation is set at defiance." But it is precisely where explanation seems set at defiance, that the true student of ^Nature is most hopeful of gaining instruction. The observation is very startling, it is true ; and the explanation may be expected to be also surprising. But I think it is not far to seek. The satellite cannot have retraced its course ; Jupiter cannot have shifted his place ; our atmosphere cannot be in question: surely, when all these explanations are eliminated, our task is rendered easier instead of more difficult. A change of shape in Jupiter, corresponding to that which I have endeavored to exhibit as explaining Saturn's occasional assumption of the square-shouldered aspect, would obviously account for the phenomenon. We know that Schroter suspected an apparent flattening of portions of Jupiter's outline. Here we have an effective confirmation of that long-doubted observation. If we consider the matter rightly, the observation made simultaneously by Smyth, Maclear, and Pearson, makes that view all but certain, which in the text I have presented only as a highly-probable hypothesis.

In preparing the Maps for my new Atlas (now nearly ready), I have detected signs of systematic aggregation among stars visible to the naked eye, which seem to me to place beyond all question the fact that Sir "William Herschel adopted an erroneous hypothesis as the basis of his system of star-gauging. The fact that about one-third of the lucid stars are collected in a region having the greater Magellanic Cloud nearly in its centre, and covering less than one-sixth of the heavens, has never yet, so far as I am aware, been noticed. Supplemented by other facts detected during the work of transferring the stars of the British Association Catalogue to my Maps, the existence of this rich region around the ^Tubeculse disposes at once of the hypothesis of a generally uniform distribution within the sidereal system. I shall be enabled, by Mr. Brothers's kindness, to illustrate my Lecture on the Stars at the. Royal Institution on May 6th by means of photographs of the Maps which thus conclusively (at least in my opinion) establish the theory that there exist special and discernible laws of aggregation among the lucid stars.

I may add in this place that it is not the case, as has been recently asserted, that my theories respecting the sidereal system have been founded on the discovery that certain nebulae are gaseous. That discovery, so far from being opposed to the theories of Sir William Herschel, afforded most striking evidence of his wonderful reasoning powers, since he had been led to express his firm conviction that many nebulae are gaseous, had confidently asserted that the Orion nebula is so, and had even anticipated the discovery of the variability of the irregular nebulae, recently effected by Le Sueur of Melbourne.

My theory respecting the sidereal system has been based on the signs of systematic aggregation among the lucid stars, and of a more intimate association of those stars with the Milky Way than could be expected were Sir William Herschel's fundamental theory correct. My first paper on the subject, in the io PREFACE.

Intellectual Observer for August, 1867, was entitled " Notes on Star-Streams ; " and it was only while inquiring into the nature of stellar aggregation that I was led to notice the laws of nebular distribution, and so to inquire into the relations between stars and nebulse. I take this opportunity of thanking my kind friend, the editor of the Intellectual Observer and Student, for the exceptional liberality with which he has found a place for views professedly opposed to generally-received opinions.

The theory brought forward in the chapter on Meteors and Comets is not altogether new. The general idea on which it is grounded has been dealt with by Mayer and Thompson, while the relation between the motions of discrete bodies and the formation of systems of orbs has been dealt with by Sir John Herschel, in considering his father's hypotheses respecting the nebulse. That idea, however, presented itself independently to my mind when I was writing my treatise on Saturn (at which time . my acquaintance with scientific literature was very limited indeed), and is definitely stated in Note B of the Appendix to that work. The line of reasoning is wholly new, I believe, by which I have endeavored to show that those peculiarities of the solar system which have hitherto been regarded as affording the strongest objection to the hypothesis of development, may be regarded as in reality the direct result of the processes by which the solar system has reached its present condition. In the preface to my treatise on Saturn I touched on the possibility that some such explanation of those peculiarities might be found, remarking that in the rings of Saturn astronomers may one day recognize the action of the processes by which the solar system has attained its present state.

In the chapter on the Sun I have entered at some length into the subject of the solar corona, partly because that subject is full of interest in view of the approaching total solar eclipse visible in the south of Europe, and partly because I have seen with regret that an erroneous theory of the corona has been recently promulgated, which seems likely at the present conjuncture to affect mischievously the progress of research into this interesting question of solar physics. I have heard with much pleasure that the Astronomer Royal, at the last meeting of the Astronomical Society, altogether repudiated any share in starting this theory. Although I had seen his name associated with it, I had always thought it incredible that a mathematician so skilful and clearsighted should have advanced or adopted so ill-considered an hypothesis.

I tender my best thanks to Mr. Browning, F. E.

l2 PREFACE.

A. S., for the beautiful colored pictures of Jupiter and Saturn, which illustrate the chapters on those planets ; and to Mr. Brothers, F. E. A. S., for his careful revision of the proof-sheets, and the detection of more than one error which had escaped my scrutiny.

Richard A. Prootor.

Lokdon, April 12, 1870.

Contents

CH4V. PAGE

INTRODUCTION . . . . . .17

I. — "What the Earth teaches us 22

Introduction

Astronomy and Geology owe much, of their charm to the fact that they suggest thoughts of other forms of life than those with which we are familiar. Geology teaches us of days when this earth was peopled with strange creatures such as now are not found upon its surface. We turn our thoughts to the epochs when those monsters throve and multiplied, and picture to ourselves the appearance which our earth then presented. Strange forms of vegetation clothe the scene which the mind's eye dwells upon. The air is heavily laden with moisture to nourish the abundant flora; hideous reptiles crawl over their slimy domain, battling with each other or with the denizens of the forest ; huge bat-like creatures sweep through the dusky twilight which constituted the primeval day; weird monsters pursue their prey amid the ocean-depths : and we forget, as we dwell upon the strange forms which existed in those long-past ages, that the scene now presented by the earth is no less wonderful, and that the records of our time may perhaps seem one day as perplexing as we now find those of the geological eras.

Astronomy has a kindred charm. We cannot indeed examine the actual substance of living creatures existing upon other celestial bodies ; we cannot even picture to ourselves their appearance or qualities ; and only in a few instances can we even form any conception of the conditions under which they live. But we see proofs on all sides that, besides the world on which we live, other worlds exist as well cared for and as nobly planned. Nay, we see globes by the side of which our earth would seem but as a tiny speck ; we trace these globes as they sweep with stately motion on their appointed courses ; we watch the return of day on the broad expanse of their surface ; and we see systems of satellites which are suspended as lights for their nocturnal skies. We further find that our sun is matched by a thousand thousand suns amid the immeasurable depths of space ; and the mind's eye pictures other worlds like those which course around the sun, travelling in stately orbits around his fellowluminaries.

Long, however, before the wonders of modern astronomy had been revealed to us, men of inquiring minds seem to have been led, as by an irresistible instinct, to examine into the resemblance which may exist between our world and other worlds surrounding it on every hand. It has not been the mere fanciful theorizer who has discussed such questions, but men of the highest eminence in science. In long-past ages Anaxi-

mander and Pythagoras studied the subject of other worlds than ours ; later, such men as Huyghens, G-alileo, and Newton, have dwelt upon the same interesting theme ; while, in our own day, Whewell and Brew r ster have employed their scientific and dialectic Ekil] in defending rival theories upon the subject.

Undoubtedly a large share of the interest with which the question of other worlds than ours has been regarded, is due to the fact that, as the science of astronomy has progressed, the subject has continually presented itself under new aspects. The question, in fact, is one of those which are ever new and ever old. It has all the charm belonging to subjects which men in all ages have delighted to discuss, while it is associated in the most intimate manner with the progress of modern science. With what a charm of novelty, for instance, the discussion between "Wliewell and Brewster invested the subject ! No doubt a large portion of that charm was due to the personal qualities of the two disputants. Yet, despite the skill with which each of them presented the arguments belonging to his own side of the controversy, few could have read with any interest a discussion on a subject so well worn, had it not been that the arguments were drawn from the discoveries which had recently been made by astronomers. Nor was it uninteresting to notice how these discoveries at once seemed to acquire a new interest when they were associated with the subject of life in other worlds. Facts which had attracted little notice at the time of their discovery, at once assumed importance, when it was seen how they bore on the rival views which Whewell and Brewster were enforcing. The interest with which the public regard many of these discoveries may, indeed, be said to date from the controversy between those eminent men.

No very long interval, if we connt by years, has elapsed since the " Plurality of Worlds " and " More Worlds than One " were written. Yet so rapidly has science progressed, that already the subject of life in other worlds has assumed a new aspect. Arguments which were hypothetical thirty years ago have either become certainties or been disproved. Doubtful points have been cleared up ; a new meaning has been found even in those facts which were well known to both the disputants; and lastly, a new mode of research has been devised, which has not only revealed a number of surprising facts, but promises to work yet greater marvels in the years which are to come.

One is thus invited to discuss anew a subject which but a few years since seemed thoroughly sifted by the inquiries of the two eminent philosophers I have named. We stand in a position much more favorable for the formation of just views than that from which Whewell and Brewster surveyed the planetary and stellar systems. Never, since men first explored the celestial depths, has a series of more startling discoveries rewarded the labors of astronomers and physicists than during the past few years. Unhopedfor revelations have been made on every side. Anal ogies the most interesting have brought the distant orbs of heaven into close relationship with our own earth, or with the central luminary of the planetary

INTRODUCTION- 21

scheme. And a lesson lias been taught us which bears even more significantly on our views respecting the existence of other worlds : we have learned to recognize within the solar system, and within the wondrous galaxy of which our sun is a constituent orb, a variety of structure and a complexity of detail, of which but a few years ago astronomers had formed but the most inadequate conceptions.

My object, then, in the pages which follow, is not solely to establish the thesis that there are other worlds than ours, but to present, in a new and I hope interesting light, the marvellous discoveries which have rewarded recent scientific researches. Judged merely according to their direct significance, these discoveries are well calculated to excite our admiration for the wonderful works of God in His universe, and for the far-reaching scope of the mental powers which He has given to His creature Man. But it is when we consider recent discoveries in their relation to the existence of other worlds, when we attempt to form a conception of the immense varieties of the forms of life corresponding to the innumerable varieties of cosmical structure disclosed by modern researches, that we recognize the full significance of those discoveries. Although the growth of our knowledge is ever accompanied by a proportional growth of our estimate of the unknown we seem already entitled to say that we have

Come on that which is, and caught The deep pulsations of the world, iEonian music, measuring out The steps of time.

CHAPTEE I.

WHAT OUR EARTH TEACHES US.

.Befoke proceeding to consider the various circumstances under which the worlds or systems which surround us appear to subsist, it may be well to inquire how far we have reason to conclude, from the consideration of our own earth and its inhabitants, that the Creator has designed the orbs which exist throughout space for the support of living creatures.

It would not be just to argue directly from the fact that the earth is inhabited to the conclusion that the other planets are inhabited also, nor thence to the conclusion that other stars have, like our sun, their attendant worlds, peopled with various forms of life. An analogy founded on a single instance has no logical force. And it is doubtful whether we have not, in the moon, an instance which would as effectually serve to support a directly opposite conclusion. It seems all but certain, as we shall presently have occasion to show, that no part of the moon's globe is inhabited by living creatures. Certainly she is inhabited by none which bear the least resemblance to those existing on our earth. Thus it might fairly be urged that, since

WHAT OUR EARTH TEACHES US. 23

one of the two orbs respecting which we know most appears to be uninhabited, there remains no probable argument in favor of the view that other orbs besides our earth are the abode of living creatures.

Yet the earth in reality supplies an argument of great force, when we consider the evidence she presents in another light. The mere fact that this world is inhabited is, as we have seen, little ; but we shall find that the way in which life is distributed over the earth's surface is full of significance.

If we range over the earth, from the arctic regions to the torrid zone, we find that none of the peculiarities which mark the several regions of our globe suffice to banish life from its surface. In the bitter cold within the arctic circles, with their strange alternations of long summer days and long winter nights, their frozen seas, perennial ice, and scanty vegetation, life flourishes in a hundred various forms. On the other hand, the torrid zone, with its blazing heat, its long-continued droughts, its strange absence of true seasonal changes, and its trying alternations of oppressive calms and fiercelyraging hurricanes, nourishes even more numerous and more various forms of life than either of the great temperate zones. Around mountain-summits as in the depths of the most secluded valleys, in mid-ocean as in the arid desert, in the air as beneath the surface of the earth, we find a myriad forms of life.

But this is far from being all. Various as are the physical habitudes which we encounter as we travel o^er the surface of our globe, we are able to trace the existence of other varieties even more remarkable.

The geologist has been able to turn back a few leaves of the earth's past history, and, though the pages have been defaced and mutilated by Time's unsparing hand, he is yet able to read in them of many strange vicissitudes to which the continents and oceans of our globe have been exposed. But, far back as he can trace the earth's history, and already he counts her age by millions of years,* he finds no evidence of an epoch when life was absent from her surface. Nay, if he reads aright the mysterious lesson which the blurred letters teach him, he is led to believe that, at the most distant epoch to which his researches have extended, there was the same wonderful variety in the forms of life as at the present day. He can, indeed, find the scattered remains of only a few of those old-world creatures ; but he recognizes, in those which have been preserved, the clearest evidence that thousands of others must have existed around them. He knows that, of a million creatures now existing, scarcely one will leave to future ages any record of its existence ; he sees whole races vanishing from the earth, leaving no trace behind them ; and he is thus able to form an

* The results of the recent deep-sea dredging expeditions, though they have an obvious bearing on the question of the relative ages of the various strata of our earth, do not appreciably affect our estimate of the range of time during which this world has been the abode of living creatures. We can no longer assume that adjacent rocks which differ in character are necessarily different in age : but we have enough evidence, from superimposed strata, to prove the enormous antiquity of the earlier formations. The researches of Dr. Carpenter and his fellow-workers have a most important bearing, however, on the subject of the present chapter, and supply a more forceful analogy, perhaps, than any dwelt on in the text, in favor of the view that, under the widest varieties of con. lition, Nature may be most prodigal of life.

WHAT OUR EARTH TEACHES US 2S

estimate of the enormous extent by which the creatures and races of which he can learn nothing must have outnumbered those whose scattered remains attest their former existence upon the earth.

Here, then, we have analogies which there is no mistaking. We see that not only is Nature careful to fill all available space with living forms, but that no time over which our researches extend has found her less prodigal of life. We see that, within very wide limits, she has a singular power of adapting living creatures to the circumstances which surround them. Nor is this lesson affected — like the general lesson drawn from the mere fact of the earth's being inhabited —by any thing we can learn from the aspect of our satellite. For the arguments against the presence of living creatures on the moon are founded on the evidence we have that the physical habitudes of that orb are outside the limits — wide as they seem to be — ■ within which Nature can effect the adaptation we have spoken of.

In fact, if we consider rightly, the argument which has been drawn from the moon's presumed unfitness to be the abode of living creatures is so founded on terrestrial analogies as to leave the contrary argument unaffected. We have to assume that the argument drawn from the analogy of the earth is forceful before we can form any opinion at all respecting the moon's habitability. And, in any case, no argument can be drawn from the moon's unfitness for the support of life, against the view that, where orbs fit for the support of life exist, there Nature has provided such classes of living creatures as are adapted to the special habitudes of those orbs.

The moon teaches us, however, that the Creator has not intended all the celestial bodies to be at all times habitable. The sun also teaches the same lesson. And it is necessary that we should consider how far the evidence presented by our own earth may serve to elucidate this teaching. We shall see, as we proceed, that terrestrial analogies afford a very sure guide in the midst of many perplexities which the study of the worlds around us presents to our contemplation.

Let us trace out the various degrees of fitness or unfitness for the support of particular forms of life, which we recognize in various regions of our earth.

Often, where there exists so slight a difference between two regions of the earth that, to ordinary observation, it would appear that the forms of life existing in one should be well adapted to the other also, we yet find that this is not the case. Some minute peculiarity of soil, or climate, or vegetation, will render one region absolutely uninhabitable by a race which lives and thrives in the other. Darwin mentions several instances in which an apparently insignificant change in the circumstances under which a particular race has thriven, and sometimes a change which does not, at first sight, appear to be in the least connected with the well-being of the race, has led to its gradual disappear ance. And it seems demonstrated that even the slow processes of change to which every part of the earth is subjected would suffice to destroy a number of the races now subsisting on its surface, were the character

WHAT OUR EARTH TEACHES US. 2 j

istics of those races unalterable. But, as the physical habitudes of their abode slowly change, the various races of living creatures slowly change also, so as to adapt themselves continually to the varying circumstances under which they live.

The lesson taught us by this peculiarity is very obvious. On the one hand, we see that it would be by no means sufficient to indicate a general resemblance between the physical habitudes of our earth and those of some far-distant planet, in order to prove that that planet is the abode of living creatures resembling those on our own earth. But, on the other hand, we are taught that the existence of differences sufficient to render a distant planet an unsuitable abode for such creatures as we are familiar with, cannot force upon us the conclusion that the planet is uninhabited. On the contrary, the circumstance we have been considering teaches us, that such differences as would suffice to banish life of certain kinds are insufficient to banish life of all kinds, or even to render less abundant the forms of life which exist under those changed conditions.

Aud now we may proceed a step farther. On our earth we find differences of climate and of physical habitudes generally, which are much more important than those hitherto dealt with. "We see that not only would certain races perish in the long-run, if removed from their own abode to other parts of the earth, but that, in some instances, the process of destruction would be very rapid indeed. If we were to remove the polar bears from their arctic fastnesses to tropical, or even to the warmer parts of temperate regions, a very few years would see the end of the whole race. The races inhabiting steppes and prairies would quickly perish, if removed to mountain-regions. Those accustomed to a moisture-laden air and abundant vegetation would not survive long if removed to the desert.

In some races, indeed, we find a power of enduring such changes which very far exceeds that possessed by other races. Those creatures, for example, which man has domesticated seem capable of enduring a variety of climate or of circumstances, which would destroy the seemingly more vigorous races which have not been subdued to the yoke of man.*

Even man himself, however, though he possesses in an unrivalled degree the power of enduring in safety the most complete change of climate, scene, and circumstances, is yet limited, in a certain sense, in his power of migration. The Englishman, for example, can endure the fiercest heat of the tropics or the bitterest cold of arctic and antarctic regions. But he cannot safely attempt to found true colonies in every part of the earth's surface. Our countrymen in India must send their children to be reared in England, if they wish them to grow up strong and vigorous. There can be little doubt that if a thousand men and

* Humboldt tolls us that " the pliability of the organization of those animals which man has subjected to his sway, enables horses, cows, and other species of European origin, to lead for a time an amphibious life, surrounded by crocodiles, water-serpents, and manatees. When the rivers return again to their beds, the horses roam in the savannah, which is then spread over with a fine odoriferous grass ; and enjoy, as in their native climate, the renewed vegetation of spring."

WHAT OUR EARTH TEACHES US. 2 g

women from this country were to settle in certain parts of India (not at any time intermarrying with the natives), the colony wonld have disappeared within a couple of centuries.

Here we have a second degree of unfitness, according to which certain countries would quickly become depopulated, if supplied with inhabitants from certain other countries. We are taught the same lesson as before, but in a more striking manner. We see that differences exist within the confines of our own earth, which render particular countries absolutely uninhabitable by particular races, insomuch that, though the individual might survive, the race itself would quickly perish. And we see, on the other hand, that these countries are not uninhabited, or even less fully peopled with living creatures, than seemingly more fortunate abodes.

Now, if some impassable barrier prevented the inhabitants of one country from visiting others, while yet it was possible to learn something of the conditions prevailing in other regions, how readily the conclusion might be reached, that some at least of those inaccessible regions must be wholly uninhabited, simply because their physical habitudes appeared un suited to the wants of the only creatures with which the observer was familiar. Who would believe, for example, that men can live, and not only live but thrive and multiply, in the frost-bound regions within the Arctic circle, if travellers had not visited the Esquimaux races, and witnessed the conditions under which they subsist ? Again, if we knew nothing of India, and some one pictured to us the intense heat of the Indian sun, the strange alternations of weather which replace to the Indian the seasonal changes we are familiar with, and all the other circumstances which render tropica, regions so different from our English home, who could believe that, amid those seemingly unendurable vicissitudes, there are races of men that thrive and multiply, even as our people in their temperate zone ? *