• ºº 4 *-•∞º ，•* •• 4 • №j}*I} ：~ae！•ſººſ ºſ | <！ - . . . … ••• • • • • • • • • • • • • • • • • • • ×· • • • • • ！=） *（， ， ， .Mae ！ • • • • • • • • • • • • • • • • • • • • •••••• • • • • • • → ∞， √æ√∞∞∞∞ • • • • • ';', ' -. * * -ae, ' , * *∞ × º : ••rae, ſ søn, º → © ، ™Ō~--~ ° • ×. ， ſ«） ***، · · · · · · · · · · ·，≤earra-，…，∞a s√≠√∞a √æ√ -- ！ ، ،（~~~~（~~~~**~~~~ ~~~~，~~ ~~~~ ~ ~ ~ ~- ~∞ ſaeº · · · · · ·Ō 5 No member shall draw more than two vol- 3 umes at a time. He shall not retain a book longer than two weeks without renewal, nor longer than four weeks without special dis- pensation from the Society, and every mem- Q|| ber shall incur a fine of five cents per week upon each volume after the expiration of the $º time specified above, for retaining books of Š the Library-By-LAws, SEC. S. RULE 2. § §§. & sº §Sººgº 3. £33-º CO2 SXi \ #: # ÉÉ. TºS :55.33:55 S㺠\\ Tºm// -- º wº ºx º y "ºſ" - & J.' - - - #x: - - \ , - - i. -º - - - */sº sº." - - - x º º º' º ºr Nº. - º ºny.”// º 4 × 4 + sums ºn a ºpmnuº'ſ --- ºf = \ º - ºsmº zoº. º º TX. º º º -- ^ º º ºff snº, - - - - - - º _-ºf- - tº ºs ºf - - ºna * --- - - - - cº-w; 4 J 487.3 º' *.*.*.*.*.*.**** **** * * ***. OF THE ARCHITECTURE OF THE H E A V E N S. IN A SERIES OF LETTERS TO A LADY. º BY J. P. NICHOL, LL.D., F.R.S.E., PROFESSOR OF PRACTICAL ASTRONOMY IN THE UNIVERSITY OF GLASGOVV. REPUBLISHED FROM THE LAST LONDON AND El)INBURGH EDITIONS : T0 WHICH HAS BEEN ADDED NOTEs, A GLoss ARY, &c. BY THE AMERICAN PUBLISHERS. * NEW YORK : H. A. CHAPIN & CO, 138 FULTON STREET. 1840. Entered, according to Act of *gress in the year 1840, by H. A. CHAPIN & Co. in the Clerk’s office of the District Court of the United States for the Southern District of NEW YORK. PR EFACE. “I HoPE mone of my readers will expect in this volume a general treatise upon Astronomy: I have not written systematically even upon that portion of the science the results of which I intend to expose. It has been my sole aim to state what recent times have evolved concerning the vastness of the Universe, in language so plain, that whoever wills, may henceforth look at the Heavens not without something of the emotion which their greatness communicates to the accomplished Astronomer; and if, if performing this task, I sometimes abandon the style of strict discussion, substitute illustration for proof, or give speculation free wing, perhaps the scientific reader who discovers the offence, will, if he approve of my plan, ac- count it venial,—The Plates are chiefly taken from gra- phic representations by the two Herschels —in most cases they will amply compensate for the want of powerful telescopes.” The preceding extract from the author's preface to the London and Edinburgh editºhs, sufficiently illustrates his views and the nature of the present work. To this he adds, in the last edition, his acknowledgements for the dis- tinguished favor with which the volume has been received by the public; and, encouraged by its rapid sale, he says “I may perhaps venture to hope that it has succeeded in familiarizing many of my countrymen with the sublime truths unfolded by the higher Astronomy;” and further, that in this edition, “the reader will find a few of the more abstract parts considerably simplified. It is also enriched by an account of those admiral researches concerning the Double Stars which have lately reached this country, from the Imperial Observatory of Dorpat.” In presenting this work to the American public, the publishers have been greatly encouraged by the opinions of their literary friends, in addition to their own convictions of its singular merits and elevated character; and they are therefore gratified in believing that in its republication they will contribute much to the dissemination of valuable knowledge among their countrymen upon one of the most useful and exalting subjects of human inquiry. The fact that the work has already gone through three editions in iv PREFACE. Great Britain, and that the few copies recently imported to this country were immediately and eagerly purchased at a very high price, will appear conclusive as to the esti- mation in which it is held by the public, both here and in Europe. Indeed, the publishers feel justified in the opinion that a more valuable and interesting volume has not been of late issued from either the American or English press. The startling, and to most readers, movel facts and con- clusions with which this work abounds, respecting the origin, the nature, and the magnitude of the heavenly bodies cannot fail to interest all who glance at the subject. Nor is it unworthy of notice that whilst most of these truths, and particularly those revealed by the late researches of Astronomers in firmamental nebulae, are confined to learned and elaborate foreign treatises, generally too technical or abstruse for the ordinary reader, the present work is indited in plain, but glowing and ele- wated language, comprehended by, and alike inspiring to all. The eminent talents of the author and professor of Astronomy in a celebrated:European University, affords also, satisfactory evidence Öf the truth and interest of the work, and, at the same time, good reasons for the confi- dence with which it has inspired the public mind. . The publishers have prepared and appended a copious GLoss ARy, in which are explained all the scientific terms and words of doubtful meaning occurring in the work. This they believe will be useful to general readers, with whom it is their desire to render the work acceptable. NotEs have been added, the more clearly to illustrate occasional remarks by the author, and, if possible, to give additional interest to the volume. MAPs of THE Con- STELLATIONs have also been prepared with care, which will, it is believed, render the whole still more valuable, as they, with the Glossary, may be frequently referred to. The original is departed from only in some few words and marks calculated to render the text more clear; and the numerous illustrations are presumed to be equal if not superior. It is also of some importance to the majority of readers that, instead of $4.50, the price of the foreign vol. ume, the republication with its additions, is offered at $1.75. THE PUBLISHERS. New York, August, 1840 C O N T E N T S. PART I.--THE GENERAL OUTLINEs of THE ExistiNG UNI- LETTER I.-Considerations on the System of the Uni- verse—Shape of that great Cluster or Firmament Within which our Sun is imbeded. . . . . . . . . . . . . . . . . 2 LETTER II.-The power and reach of Telescopes...... 20 LETTER III.-Aspects, Forms, and Distances of remote Clusters. . . . . . . . . . . . . . . . . . . . . . . . . • - - - - - - - * g º e s it tº 29 PART II.—THE PRINCIPLE OF THE VITALITY, or of THE INTERNAL MECHANISM OF THE STELLAR CLUS- TERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 LETTER IV.-Probable Universality of Planetary Sys- tems—Relation of neighboring Stars to each other— Opening of the Question. . . . . . . . . . . . . . . . . . . . . . . . . 35 LETTER V.—Triple and more intricate combination— Existence of Large Groups—Conjectures respecting. the Forms and Distribution of Clusters. . . . . . . . . . . . . 62 PART III.--THE ORIGIN AND PROBABLE DESTINY OF THE PRESENT ForM OF THE MATERIAL CREATION. 71 LETTER VI.-The Nebulae. . . . . . . . . . . . . . . . . . . . . . . . . . 71 LETTER VII.-The Nebular Hypothesis.............. 85 LETTER VIII.-Speculation.... . . . . . . . . . . . . . . . . . . . . . 108 NOTES. NoTE A-Planetary System . . . . . . . . . . . . . . . . . . . . . . .'• . . . . 117 NotE B.—Orbits of Double Stars..... . . . . . . . . . . . . . . . . . . 119 NoTE C.—Geological Changes. . . . . . . . . . . . . . . . . . . . . . . . . . 121 NoTE D.—Locality of Objects in the Plates . . . . . . . . . . . . . . . 123 NOTE E.—Organic Remains. . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 NotE F.—Constellations. . . . . . . . . . . . . . . . . . . . . . . . • * * * * * * 132 NotE G-Nebulae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 NotE H.—Fixed Stars. . . . . . . . . . . . . . . . . * * * * * * * * e º 'º º ſº e º e 136 NoTB I-Gravity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 NOTE J.—Biographical Sketches.... . . . . . . . . . . . . . . . . . . . . 142 GLOSSARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 PLA. T E S. e e s e e e s e º s e º e º e º e º & © a * * * * * * g c e s a e CoNSTELLATIONs to front the title. " P A R T I. GENERAL OUTLINES OF THE EXISTING UNIVERSE. L E T T E R I. consid ERATIONS ON THE SHAPE OF THE UNIVERSE— SHAPE OF THAT GREAT CLUSTER OR FIR MAMENT wiTHIN which ou R SUN IS IMBEDDED. MADAM, I HAVE been induced to make the brief series of letters addressed to you thus public, because of a regret which, I believe is widely felt, that the discoveries of recent years, which have thrown unexpected light upon the con- stitution—present and remote—of the Stellar Universe, should longer continue comparatively uuknown, or con- cealed amid the varied and massive collections of our Learned Societies. Unfortunately, I am not at present in a condition to bestow on these discoveries a shadow of original interest; so that, in description, my pen can have only a borrowed liveliness. But as the illustrious men who share the glory of having achieved such acquisitions for mankind have, not unequivocally, declined the hum- bler task of reducing them into a popular system, we have only the choice of consenting that matter of unusual im- portance shall remain unfitted to fulfil the best purpose of truth—which is to instruct and elevate the general mind,-or to permit the work to be attempted by some one with pretensions no higher than my own. Previous to the commencement of this century the facts and speculations about to engage us were unknown in science. Before then, the planetary orbits seemed to encircle all accessible space: they had effectively con- stituted bounds to systematic inquiry; for astronomers had never adventured into greater remoteness, having, like the people, gazed at the farther heavens with vague 1 Af S - SIR W II, LIA M H E RSC H E L. and incurious eye—content to admire their beauty and confess their mystery. This period, however, was dis- tinguished by the occurrence of two cvents, which could not exist in combination, without ensuring important re- sults. The TELEscope, formerly of limited range, sud- denly assumed a capability of sounding the uttermost pro- fundities; and the man in whose hands it took on this mew efficiency, was possessed of a genius to which all opportunities could be entrusted, for it was adequate to the highest. The rise of SIR WILLIAM HERscIIEI, marks the first, and still the greatest epoch of the modern astro- nomy. He was struck for a discoverer in the finest mould:—mingling boldness with a just modesty, a thirst- ing aſter large and general views, with a peculiar sensi- tiveness in regard to eſcisting analogics, and a håbit of most scrupulous and dutiful obedience to their intima- tions—he was precisely the man first to quit paths, which through familiarity were common and safe, and to guide us into regions dim and remote, where the mind must be a lamp to itself, and walk entirely by lights which stream from its internal fountains. There is one infallible mark of the rise of an original mind. When you see a man in the midst of his contem- poraries, mot contesting opinions; not quarrelling, but quietly, and without either ostentation or fear, proceeding to resºlve by reason, subjects which had hitherto been in possession of “common belief.”—be certain that a signal accession of knowledge is awaiting us, for the freshest stamp of divinity is upon that man. Herchel's first re- markable paper gave a promise of this description, and abundantly was it soon fulfilled. It seems to have early occurred to him that the notions—still prevalent—con- cerning the relation of our firmament,” or whole heavens, to the universe, or rather to infinite space, rest on no bet- ter foundation than many long discarded conceptions which found easy acceptance in less advanced epochs of astron- * Once for all, and to prevent ambiguity, let me state, that in speaking of our firmamcnt, I mean, not the solar system, but that entire mass of stars, of which, what we see in a clear night is the nearest portion. It will be seen in the sequel, that the propor name for this mass, is own cluster. - -- our views AND THE INDIAN's For EST. 9 omy. The usual inference from the aspects of the sky is, I believe, that our skies are infinite, or that stars, as we see them, stretch through all space; which, critically ex- amined, appears only a repetition of the old fallacy, that what is great to us, must be great absolutely, and to all beings, that, a system must be infinite, occupying and constituting creation, merely because we cannot descry its boundaries, or reckon up its magnitude by the dimensions of our narrow abode. The firmament, with its countless and glorious orbs, is doubtless vast,-perhaps inconceiva- bly so; but, calmly placing the utmost sphere within our possible sight, beside the idea of what is really infinite, or comparing the vision of man with the reach of an Al- mighty eye—it flashes instantly upon us that we neither have nor can have positive ground for the assertion that our stars are diffused through all existence. Herschel proceeded to refute systematically this common delusion, and to unfold the true scheme of the universe. & The subject is very unusual, and exceedingly apt to bewilder and overwhelm ; so that we shall most safely enter it by aid of illustration; and one occurs to me which exhibits with some precision the progress of our Dis- coverer's thoughts.-Call up to your mind an Indian of that old America, when sº had not yet disturbed the sombre twilight of its forests; suppose him of a tribe whose wanderings had been confined far within the in- terior of a range of primeval pines, how matural for his untutored thought to conceive the wood of his nativity in- finite, or that space is all occupied with trees' His eye had never lighted upon one external object; the forms of his infancy were the forms to which his manhood had been alone accustomed; trees had always environed him, and hemmed in his prospect; so that, on being informed by an instructed traveller of the existence of free and wide Savannahs, he must have seemed to hear of sounething unintelligible and against nature, and have gazed with that very incredulity which fills our minds at the idea of the great Firmament being limited like a Fort st—of owr Infinite being comprehended within Form. But lo!— in his stray wanderings—at a time when his gods smiled 10 EXTERNAL FIR MAMENTS, upon him—the Indian arrives at a mountain, which rears its summit above the gigantic pines. He attemps it, ovel- comes its precipices, and descries—a new world! The forest of his dwelling is mighty, and stretches far; but America is mightier, and numbers of forests equal to his, luxuriate upon its plains. Seldom, indeed, is this moun- tain' found. Men wander through centuries, in ancient ignorance, without reaching or scaling an elevation capa- ble of showing them beyond it; but in a propitious hour, and after long preparation, genius and industry descry it, and straightway the scales fall from our sight. It was the TELEscope which in this case pierced the skies, and revealed the contents of outer regions hitherto unseen by man. And most splendid was the perspective Divided from our firmament and each other by measureless in- tervals, numerous FIRMAMENTs, glorious as ours, float through immensity, doubtless forming one stupendous system, bound together by fine relationships. These re- markable masses are located so deep in space, that, to in- ferior telescopes, they seem like faint streaks or spots of milky light upon the blue of the sky; but the instruments which had just been summoned into being resolve their mystery, and disclose their myriads of stars One of these objects, perhaps the most brilliant in the heavens, is represented in Plate I. : it is in the constellation Her- cules.” After all, how easy the belief to its indwellers, that a mass thus surpassingly gorgeous is—infinite. What wonder that the inhabitant of a planet revolving around one of its central sums, should have mistaken his own magnificent heavens for the universe, and needed the dis- tant and dim vision of our firmament, appearing to his telescopes as a starry speck, to remove the veil from his mind and give him juster motions of the majesty of crea- tlOll. There are truths which, although startling at first, are found so much in harmony with the scheme of Nature, * The Plate referred to is certainly the most inadequate in the volume. It is indeed impossible to give a fitting representation of this magnificent cluster. Perhaps no one ever saw it for the first time through a large telescope, without uttering a shout of womder. PI. I. ASPECTs of THE HEAvLNs LIKE THE For EST. ii that we are soon astonished that they never occurred to us before; and I can conceive circumstances in which the Indian, after the foregoing revelation had been made to him, would not ſail to descry among the internal aspects of his forest, not only distinct intimations of its limitude, but also of its peculiar shape, and even approacimate di- mensions. Think of the appearances which would be remarked by an observant man, as characteristic of his osition, were the forest infinite or very extensive. In ; immediate vicinity the surrounding trees would be well defined, and of the largest proportions; behind these he would see another range, smaller, but also well-defiğ and so on through many gradations of size and ifistinº ness, until individual trees could no longer begistinguis h- ed, and the view would terminate in an unmaimed and vague appearance, which I may be permitted to call a diffused woodiness. But if this peculiar background were not seen in every direction, the light of the sky appearing through the trees in different places, the conclusion would be just and manifest,--that the forest had not the charac- teristics of one stretching out indefinitely, or even equally, on all sides, that in some directions its edges were nearer than in others, or that it was merely a group or stripe of trees, having boundaries, and of a particular and ascer- tainable shape. With these fresh lights, turn again to the heavens, asking what is the case with them 2 If we were in the interior of an infinite and regular stratum, appearances would necessarily be nearly similar all around us; the aspect of the sky on one side would be almost its picture on every other side. The same, or nearly the same number of visible bodies would, as in the infinite forest, be ſound every where; and there would come from behind in all directions, through those recesses in which no single star could be descried, something of the same amount of whitish or milky illumination, arising from the combined effulgence of luminaries individually unseen. But this does not accord with actual phenomena, which rather agree with the second form of onr illustra- tion. It is only when we look towards the MILKY way, that these bodies seem to retire indefinitely, and finally to be lost in a diffused starriness. In all other places the 12 FHENOMENA OF THE MILKY WAY. intervals between the luminaries are nearly quite dark, as if there we were closer on the edges of our bed of stars, and therefore saw through it into external and obscure vacancies of space. The opinion is thus forced on us anew, that what we term our Firmament is merely a group or cluster of stars, and, moreover, that it is a group of peculiar configuration, narrow, but greatly elongated in the line of the Milky Way. Is it not strange that an inference so natural, so palpable, flowing so easily from the phenomena of our brilliant zone, was never drawn before; and that, notwithstanding that zone has been shining there and speaking since “creation's dawn” most invitingly to reason, it should have been left for Herschel, at so late a day, to rescue it from mythology and mystery, and teach us to look at its countless orbs with emotions loftier than an exciting or useless wonder Starting with the foregoing general ideas, let us attempt to ascertain, with definitiveness, the shape and dimensions of that great cluster in which we are. In the remaining part of this letter I mean to guide you to the conclusion I have in view, through a series of approximations. 1. Our group, I have said, is certainly an elongated one. A simple diagram will explain how existing ap- pearances are generally accounted for by this hypothesis; and the same illustration will indicate the first rude modi- fication necessary to bring it into a more perfect and ninute consistency with appearances. If a spectator were in a world S in the midst of a stratum or bed of stars, bounded as beneath by the lines C and D, i. e. marrow, or at least, measurable in breadth, as in the directions SC, SD, but indefinitely prolonged towards A and B, he would manifestly be engirt by heavens having the general aspect ITS APPEARANCE TO THE SPECTATOR. 13 of ours; for, on looking along any line from S towards C or D, he might see through the cluster, and the regions in that quarter would, therefore, all appear a compara- tively dark ground, bespangled with multitudes of distin- guishable luminaries; while in the directions SA and SB-before and behind him—his eyes would fail, as ours do when turned to the milky way, in separating the indi- vidual bodies, or in recognising the existence of the re- moter masses, otherwise than in the silvery twilight coming from their aggregation. Were our milky zone one regular belt, we would, it is thus evident, require no modification of the previous hypothesis; for the supposi- tion that the firmament is a regular oblong stratum, would in that case clearly explain and account for its whole more prominent phenomena; but the Milky Way is not a regular belt. An attentive inspection of it, on any favor- able night, will show you, that through one-third of its entire course it divides into two branches, which, after flowing considerably apart—leaving between them a com- paratively dark space—reunite, and again form a single stream; so that you require a hypothetical figure, which will explain why, in looking before you to any part of that region where the stream is divided, your prospect terminates, not in one milky spot, but in two, separated by a considerable breadth of space which has no greater number of stars, and not much more general illumination, than the sides of the cluster. Now, this peculiarity will be accounted for, if we suppose that our cluster is an ob- long divided at one of its eactremities; for if the sun S, were in such a cluster as below, a spectator in it would l II. manifestly see one bright spot towards B; two equally bright spots, A' and A’’, in the opposite direction; and 14 TORM OF OUR FIRMAMENT. towards C and D, as before, the background of the hear vens would appear comparatively dark; while he would observe a third, but limited dark space, of precisely the same character, towards the vacuity A”, which separates the divergent branches. - The foregoing figure may thus be taken as a first, but most general approximation to a section of our vast fir- mament; and as such, I think it cannot be viewed with ordinary interest. Perhaps, however, you may find dif- ficulty in apprehending what our firmament really is, or in inferring its entire shape from its chart in section; I shall, therefore, without departing from the very general and rude mode of illustration I have adopted, endeavor to construct for you its complete or solid form. You know a common grindstone? Suppose, first, that the rim is split in the middle, along the line of the rim, and through about one-third of its circumference; which split, how- ever, does not reach so far down as the centre of the grindstone: also let the divided parts be somewhat separ- ated towards the middle of the division, so that they run along as below, and re-enter after a tempºrary separation. Supposé, secondly, that the sandstoné is considerably more porous than stone is, then let its minute atoms repre- sent stars, the pores or intervals, being the interstellar spaces; and observe what an inhabitant of a sum or world near the centre of a cluster of such configuration would erceive in his heavens. They would be precisely simi- i. to our own celestial vault. Towards their sides the view would be comparatively unadormed—dark space looming from beyond the visible stars; while, in the direction of the circumference, a countless mass of small remote stars woul", although separately unseen, illume OUR FIRMAMENT AND THE TELESCOPE. 15 the sky, forming a splendid zone, divided like our Milky Way through part of its shadowy course. Is it repulsive to compare our magnificent universe to an object so ordi- mary, so trifling 7 Alas! endow it once with Form, and, whatever its actual dimensions, beside the vastness of the Infinity which environs it, all are shrivelled up, and their majesty disappears We can speak of our cluster only as of a limited object, a speck, one single individual of an umnumbered throng; we think of it, in comparison with creation, only as we were wont to think of one of its own StarS. s. - 2. Hitherto we have used merely the eye—now we take up the telescope. Herschel employed this wonderful instrument to show him the very minute irregularities of our firmament, upon a principle easily understood. Sup- pose you were somewhere in a crowd—say, in a church filled with people—would you not, on turning and look- ing around you in different directions, see a number of persons somehow proportionate to your distance from the extremities of the crowd, or the walls of the church? If you saw a much greater number, for instance, when look- ing one way, than when looking another way, the infer- ence would surely be natural, that, in the former direc- tion, the mass or multitude of people extended farther than in the latter; and it will be quite conceivable that an arithmetical rule might be found, by which you could compute your relative distances in the two cases, from the ends or limits of the assembly. The rule does exist, and it is not complex; nevertheless, I am satisfied here if you recognise its possibility. Take them a large telescope— one which can go deeply through space—turn it in all directions, count the number of stars in its field in each position, calculate upon this basis your corresponding dis- tance from the extremities of the cluster, and you have the means, to a certain extent, of accurately charting the firmament. Herschel was fired by this idea. He termed the process a gaging or sounding of the heavens—casting out lines, as we do at sea, to fathom and record its pro- ſundities. With his peculiar ardor and perseverance, he accomplished at least 700 known observations with a view to determine the elements of a suitable and accurate & I6 HERSCHEL G.A.G.ES THE FIR MAMENT. sketch —Then supposing S the position of cur sun, and drawing, in the due directions, lines determined in length by the arithmetical rule spoken of as corresponding to depths indicated by the quantity of stars in each gage, the mere joining of the extremities of these lines gave III. him the section required. The above wood-cut is purely imaginary, being simply intended to exhibit the rationale of Herschel's method; the result actually obtained by him is shown in Plate II. It has the aspect, and is larger than the size under which that firmament—so magnificent to us—may appear to spectators in remote clusters situa- ted in a line passing through the Milky Way, and nearly over our heads;–spectators who, perhaps, are even now marvelling as they descry it through their telescopes, what that sprawling spot may be, which just somewhat, and only in one trifling point, bedims the azure of their heavens ! ” * I proposed to investigate, not only the shape, but also the di- mensions of our cluster. In respect to the latter, we cannot, of course, hope for , more than the remotest approximation. It was Herschel’s idea, that, towards the sides or shallow parts, there might be a line of forty successive stars, at equal distances from each other, between our sun and its extremities, while in the direction of the Milky Way there are in some places upwards of 900 ! The M. Way, however, is by no means equally profound It is, as we will Soon see, an extremely irregular zone. I may remark here, that the numerical statements in this note and throughout the text, are de- pendent on Herschel’s notion of the relative light or magnitude of the stars—a subject on which astronomers are by no means agreed, and which demands further and much more critical scrutiny. For the sake of the simplicity of my volume, which is essentially a sketch, I did not think fit to open the original question in the first instance; , and I still retain the estimate of this great inquirer, because the lead- ing truths I am unfolding are independent of their absolute accuracy. * HERSCHEL's CHART AND v1Ews. 17 3. There is obviously one source of error in Herschel's sketch, which we may be able to eliminate, and thus ap- proach still nearer the truth. Throughout the whole speculation you find the latent assumption, that the stays are distributed equably—not meaning that there are no small clusters within the firmament, such as the Pleiades, or the brilliant Proesepe in Cancer, but that even such clusters are scattered, generally, in all directions, on a principle approaching to indifference. Our astronomer himself searched somewhat into this matter, and he saw ... enough to convince him that his section has only the - value of an approximate representation. Towards the Milky Way, and especially within that zone, the stars are much more compressed, or closer, than elsewhere: and I find among Herschel's journals, notices of various kinds, indicating breaks in the regular progression of stars—absolute vacuities—chiefly appearing to detach the Milky Way from the interior mass, and to present it more as a RING of STARs, really separated from the rest of the stratum, but environing it. Sir John Herschel decidedly inclines to this opinion ; and he thinks, moreover, that we are not placed in the centre of the included stratum, but in an eccentric position, i. e. nearer one-half of the ring than its opposite half—thus accounting for the vastly superior brilliancy of this magnificent girdle in southern latitudes." The telescope will ultimately resolve all these The subject, however, is exceedingly interesting, and I hope to dis- cuss it fully on another opportunity. . A new field of speculation in this matter has recently been opened by Steinheil. * The following are Sir John's words:– “The general aspect of the Southern circumpolar region, including in that expression 60° or 70° of S. P. D., is in a high degree rich and magnificent, owing to the Superior brilliancy and larger development of the Milky Way: which, from the constellation of Orion to that of Antinous, is in a blaze of light, strangely interrupted, however, with vacant and almost star- less patches, especially in Scorpio, near a Centauri and the cross; while to the North it ſides away pale and dim, and is in comparison hardly traceable. I think it is impossible to view this splendid zone, with the astonishingly rich and evenly distributed fringe of stars of the third and fourth magnitudes, which form a broad skirt to its southern border, like a vast curtain—without an impression, amounting to a conviction, that the Milky Way is not a mere stratum, but an annu- lus; or, at least, that our system is placed within one of the poorer alid almost vacant parts of its general mass, and that excentrically, So as to be much nearer to the parts about the cross, than to that dia. metrically opposed to it.” IS T H E M II, KY WAY-O U R FIR M AM E. N. T. problems; for, as I will explain in my next letter, it not only brings new objects within sight, but also informs us, at the same moment, in what particular zone or sphere they are located: the labor, however, of thus dissecting our massive firmament is scarcely more than begun.—l have now to state to you a remarkable circumstance, per- haps the strangest and most unexpected which modern astronomy has revealed. Although the telescope has not yet enabled us to lay out the plan of our cluster, from in- terior surveys, it exhibits what seems its very picture, hung up in external space | Look at Plate III. It re- presents an object resting near the outermost range of tel- escopic observation, not resolved, but doubtless a great scheme of stars, which is the fac-simile of that to which we belong ! It has its surrounding ring of the precise form we have been inclined to attribute to our zone; and its section, figured in the same plate, or the aspect it would take on to a spectator at a vast distance, looking from the direction of the white line in the margin, has the closest general resemblance to Herschel's sketch.” Singular affinity of forms | What link, what far-reaching sym- pathy can connect these twin masses—that unfathomed firmament and ours? What virtue is there in a shape so fantastic that it should thus be repeated? Or what is the august law, thus working at the opposite extremeties of space, which has caused those corresponding shapes to come into being 7 Prompted by reverential curiosity, we eagerly put such questions; but to resolve them baffles our loftiest philosophies Thus then have we entered on new views; we are in- troduced to perhaps the grandest phenomena in the Stella Universe. We have been raised to an elevation never scaled before, below which Creation and its wonderful ar- rangements are expanded; and, be it never forgotten, we * It adds considerably to the interest attached to this cluster, that a spectator in it must see ours, precisely as we see it, i. e. sideways; so that our firmament will have, to the inhabitants of its stars, quite the aspect which it presents to us. The two figures in Plate III, will explain any ambiguity in pages 15 or 16, where reference is made to the section and solid form of our cluster. Perhaps these should now be reperused. LA PLACE AND NEWTON. 19 owe this conquest to the genius of one Man. But as the circle of knowledge has extended, the sphere of our re- cognised ignorance—that dark sphere which hems in what we know—has increased likewise. How different is Astronomy now, taking cognizance of the number of these firmaments, attempting to determine their magni- tude, and account for their form; from the Astronomy of a recent day, which was limited to discussions concern- ing the habits of the small bodies attending our sun, and which, because of its memorable success, boasted that as a science it was complete There was true prophecy in the exclamation of LA PLACE, who, although then know- ing more than any man of the mechanism of the Heavens, said earnestly on his deathbed, “That which we know is little, that which we know not is immense” And the spirit was partaken of by NEw To N in the very flush of his immortal discovery, when, with the modesty of all great minds, beside whose infinite aspirations the highest possible attaintment-is ever insignificant, he is recorded to have spoken thus:—“I am but as a child standing up- on the shore of the vast undiscovered ocean, and playing with a little pebble which the waters have washed to my feet.” * (20) L ET TIE R II. ON THE POWER AND REACH OF TELESCOPES. It is expedient to digress a little in this place. We have spoken much of the power of telescopes, and of the profundities through which they pierce; and it will be pleasing to you to become satisfied as to the possibility of such power—to be persuaded that I am not amusing you with romance. A brief and simple explanation of the principle on which telescopic power depends, will ac- complish this object; and you will then yield me your belief, instead of your mere confidence, when I refer again to what, but a short time ago, would have seemed an in- credible fable. Although not according to the strict mode of expres- sion, yet it suffices here to say, that we see objects, or they occasion in a spectator the sensation of sea- ing, when a certain luminous influence radiating from them, enters the eye in such a quantity as to irritate or excite the nerve of vision. Bright or visible bodies send out this influence in straight lines, and on all sides of them; so that the luminous matter will always be thinner the farther it is from the radiating point, as it cannot be dispersed without suffering diffusion—a truth which is pictorially illustrated in Fig. 1, Plate IV., where a luminous point is represented raying out beams. It follows, accordingly, that as the eye is nearer or farther from the source of the rays, the greater or less will be the amount of light received by it; and there will always be a point of distance, intended to be exhibited in the figure, where no more than is barely adequate to cause the sensation of sight, falls upon the retina. This would manifestly be the remotest limit of visibility in that case and to that eye. Let the spectator retire, although only THE EYE AND THE ACTION OF LEN SES. 21 by the smallest quantity, and the luminous point would disappear and be lost in space. Such being the process of vision, may we hope ever to extend the boundaries of our sphere, to reach depths, from which the physical constitution of humanity might appear to have excluded us? There are plainly but two imaginable methods by which so great an aim may be accomplished, either we must act upon the shining body so as to compel it to give forth light of higher intensity, or we must, if I may say so, enlarge the pupil of the eye, and enable it to receive a greater number of rays. The former method is wholly impracticable—no demonstra. tion is needed to prove it so, for bodies lying profoundly in space are manifestly remote from our control; but if by any marvellous artifice we can produce a virtual en- largement of the pupil of the eye, our success will be equally brilliant and sure. Nature, indeed, has expressly pointed out this very plan, for she acts upon it herself. Birds and other creatures which wander in the night have all large pupils, and our own organ of vision enjoys a limited power of expanding in the dusk, so that, when the light is ſaint, we take in a larger than usual ray, and dis- cern objects, which must have been unseen, unless for that preparatory change. • Turn, without farther preliminary, again to Plate IV, Fig. 2. You know a lens—a common burning-glass? Hold such a glass before the beams of the sun, and it is seen to compress much of the light which falls upon its surface into a bright pencil behind it. Suppose, now, a a large lens of this description placed immediately in front of an eye, looking towards a radiating point which is nearly invisible through faintness, and notice the change of circumstances.” Instead of the eye receiving, as in Fig. 1, only a ſaint and almost imperceptible quantity of light, it appears taking in the whole mass of rays which pass through the large lens in front of it, for the lens has united that quantity, and caused it to converge into a pen- cil sufficiently minute to enter the eye. A portion of the * It will be recollected that I am not describing the construction of a telescope, which is beyond my province and present intentions; I merely indicate the sources of its power. - 22 LEN SES THE SOURCE OF POWER. rays which reach the lens from the luminous body, do not indeed pass through it, and are therefore lost to the eye; but as the deduction is not great, the eye in the position referred to would receive nearly as much light as if its pupil had been enlarged to the dimensions of the lens, and its power would necessarily be increased in proportion. Thus armed, through what a remoteness might we reach that luminary, ſormerly just escaping us! Without the slightest hazard of its fading away, it might evidently be withdrawn into space, until the whole light compressed by the lens were not more intense at the bright point of its pencil, than the ſaint ray at the pupil in Fig. 1; and this mighty acquisition has been gaincá by the simple interposition of a lens ! We have been so long accustomed to the telescope, that Wonder has yield. ed before Familiarity; but perhaps we may yet imagine what amazement spread over Europe when the rumor was first heard, that by a process of such simplicity, the hither boundaries of the unseen had been passed, and re- mote ſaintly-twinkling worlds, brought near for the in: spection of man . No Arabian tale could have seemed wilder, and no ſabled charm of more incredible potency. Art in our own day has often seemed to realize the fa- bles of the most wonderſul talisman; but our greatest advances—our mightiest triumphs over time and space— are mean and common-place beside the achievements of the telescope. Let our race labor on the best magic— one loſtier and more potent than Agrippa ever dreamt of is all within its reach —The assistant Genius is Nature herself; and the spell, that Intellect which comprehends her. Lenses, however, or refractors, are not the sole in- struments by which light can be collected and compress- ed. A concave mirror of polished metal answers the same purpose; only, as seen in the remaining figure of Plate IV, Fig. 3, the mirror throws the convergent pen- cil forward, while refractors throw it behind them. I need not remark that the vital source of power, in either case, is the size or diameter of the reflecting mirror or re- fracting lens; for, according to its diameter, the pupil of POWER OF TELESCO PES. 23 our new eye is great or small. Refractors of a moderate size are common, but large ones are very rare-Art still failing in the regular construction of great lenses. I am assured, however, that instruments exist of this descrip- tion, through which a quarter of a mile in the moon is appreciable, and in which one of the mountains of that enigmatical luminary may be distinctly scen, and its con- tour sketched, although magnified so as to occupy the whole field of view.” It has hitherto been easier to work in metal than in glass, and accordingly powerful teles- copes, on the reflecting principle, are most frequently em- ployed, lèeflectors of nine inches diameter have long been in general use; a considerable number of twice this size have likewise searched the heavens with singular effect; but our gigantic instrument is that, perfected by Sir William Herschel, after incredible labor, whose mir- ror reached the vast magnitude of Four FEET diameter, Dwell for a short time on the dimensions and consequent power of this wonderful telescope, and I venture to say you will no longer be sceptical when I speak of seeing into space. If the mirror had reflected all the light which fell upon it, it would virtually have been an eye with a pupil of four ſect diameter; that is, it would have been more powerful than the human eye, by as much as the surface of its enormous disc exceeded the small surface of our pupilſ—And making allowance for much light be- ing unavoidably lost, still how great must have been its power | That body is faint indecd, or inconceivably re- mote, of which it could give us no hope of intimation; and it is no marvel that it sounded our firmament, mighty * The magnifying power of a telescope is not the same as the space-penetrating power, but it depends upon it. The space-pene- trating power rests wholly in the size of the speculum or object- lass—it is that power which will recognise a faint light at a great iº, the magnifying power again is chiefly in the eye-piece, which is a mere microscope, and enlarges the dimensions of the ob- ject brought by the other power into view. It is clear, however, that no object which is not presented with great light, can be greatly magnified, as its light, by being spread or diffused over, a large space, would become too thin or faint to be recognised. You may º: inſer the penetrating power of the telescope referred to in the text, from the fact that it can permit of so great an amplification of a lunar mountain, and still present as a visible and distinct object. 24 Power of HERSCHEL's TELEscop1. as it is, and ranged unwearied among the abysses of the dark Infinite beyond. The lustre with which it clothed the bodies in our immediate vicinity is said to have been inexpressibly beautiful. Herschel himself, intent on far discovery, seldom looked at the larger stars; and, because their blaze injured his eye, he rather avoided their transit. But he tells us, that at one time, after a considerable sweep with his instrument, “the appearance of Sirius announced itself, at a great distance, like the dawn of the morning, and came on by degrees, increasing in brightness, till this brilliant star at last entered the field of the telescope with all the splendor of the rising sun, and forced me to take "my eye from the beautiful sight.” º: The principles just adverted to, show how we can readily compute the precise and definite power of our telescopes, or the distance to which they reach, compared with the naked eye; and such knowledge is of the high- est importance, as, without it, we could not estimate the relative profundities of the objects which different tele- scopes reveal. The first or essential element is mani- festly the size of the speculum, or object-glass, estimated in comparison with the pupil of the eye, and the second is the proportion of light lost in the process of reflection or refraction. If no light were lost, the artificial eye and the matural eye would, as I have said, be efficient, accord- ing to the comparative magnitudes of what I may term their respective pupils; but, as light always is lost,-and the amount may be determined by careful experiment, a certain deduction must be made from the telescopic power. It would be itseless to go into the minutiae of this computation—I merely desire that you should com- prehend its grounds and rationale. A few precise state- ments, however, will be interesting. Herschel consider- ed that his ten-feet telescope had a space-penetrating power of 28%, i. e. it could descry a star 28, times farther off than the naked eye can; to one of his twenty-feet tele- scopes he assigned the power of 61, and to another of much better construction, the power of 96. The space- ºpenetrating power of the forty-feet instrument he settled at 192' But, as you may not have a sufficient idea of the profundities represented by these numbers, I shall convert GREAT SPACE-PENETRATING POWER, 25 them into more definite quantities. The depth to which the naked eye can penetrate into space, appears to extend to stars of the twelfth order of distances," i.e. it can descry a star twelve times farther away than those luminaries, which, from their superior magnitudé, we suppose to be nearest us. Multiply, then, each of the foregoing num- bers by twelve, and you have, as a first approximation to the independent power of telescopes, a new series of figures, indicating how much farther they can pience than the first or nearest range of the fixed stars. In the case of the forty-feet reflector, this number is 2304, which sig- nifies that if 2304 stars extended in a straight line beyond Sirius, each separated from the one before it by an inter- val equal to what separates the still immeasurable Sirius from the earth, the forty-feet telescope would see them all! I subjoin only one farther statement: the same instrument could descry a cluster of stars, consisting of 5000 indivi- duals, were it situated three hundred thousand times deeper in space than Sirius probably is; or, to take a more distinct standard of comparison, were it at the re- moteness of 11,765,475,948,678,678,679 miles lif # This is Herschel's computation, which, as I have said already, has been questioned. I repeat, that I shall adhere throughout to his estimates; nor will the error therein involved affect one of the general truths which I mean to expose. ... t. The limit to the space-penetrating power of telescopes is mani- festly this: No o',ject ſainter than the general light of the skies—a light constituted by the intermingling of the rays of all the stars— will ever be seen. Herschel calculated, howevcr, that a telescope, nt least three times more powerful than his, might still be used. There are mechanical difficulties in the way of grinding complete metallic specula of such a dimension, but might they not be ground in parts? In a letter addressed to me by Sir David Brewster, on the occasion of our proposing to erect a new and splendidly-furnished Observatory in Glasgow, is the following interesting paragraph — “To such an Observatory, where the finest achromatic might be ac- companicſ with a better reflecting telescope than has yet been made, it would be a leading object to delineate with precision the hills and valleys of the moon. This planet is much within our reach ; and an accurate knowledge of the phenomena it presents, and of the changes they undergo, would be a great and most interesting contribution to science. When we compare the telescope in Newton's time to that of Sir William Herschel’s, we need scarcely despair of discovering the structures º by the inhabitants of that luminary. An achro- matic object-glass of the same size as the speculum of Sir William Herschel's forty-ſeet teleseope, would certainly accomplish this; and 26 SPACE-PENETRATING POWER OF TELESCOPES, It is important to remark, that one telescope may be easily adjusted to different space-penetrating powers. Its highest power is, of course, defined and limited by the diameter of the speculum; but we have only to confine that speculum, to contract its pupil, by placing an opaque circular rim of greater or less breadth around the mouth of the tube, to obtain whatever degree of inferior reach we desire. This artifice enables us to take, without trouble, an observant walk through space. We know, for instance, that the naked eye can perceive stars of the twelfth order of distances, so that whatever we see with- out telescopic aid must lie within the sphere at whose outer circumference stars of that order are placed. . . A telescope with a space-penetrating power of 2, or which reaches to the 24th order of distances, will of course show us much more than the maked eye; but, whatever addi- tional it reveals, must in the main, lie between stars of the 12th and stars of the 24th order; so that we have not only new discoveries, but a view of the contents of that particular stratum, or layer, of the firmament which sur- rounds our visible sphere." By employing a power of 3, no person can say that it is impracticable to do in glass what we have done in metal. Had I the means, I would not scruple to under- take the task of building the lens in zones and segments.” No man can doubt that knowledge sufficient to immortalize our age would result from an instrument like that referred to by this distinguished philosopher, although the mechanical arts have not yet furnished us with an apparatus which would ensure its being easily used. The unwieldiness of Herschel's large telescope was one great cause of its comparative failure as an instrument of discovery. * I doubt not you will start a question here: Is not this conclusion dependent on the hypothesis that stars are all of the same magni- tude 2 For instance, a number of bodies descried by the space-pene- trating power referred to, may be very small, and concealed from the maked eye by their smallness, not by their distance; so that they may lie much nearer to us than even the twelfth order of distances. I freely grant that we have good reason to believe that the stars vary in size,_perhaps the limits of magnitude, i. e. the size of the largest and the sumallest, are very remote from each other : the connection of double stars of very ãº. magnitudes (see Part II.) demon- strate this; and the same might be deduced from the theory given of the formation of stellar bodies, in Part III. of our work. The specu- lations over which we have gone, however, depend only on the as- sumption that we may assume a certain mean or average magni- tude; in other words, that the bodies of different magnitudes are somewhat equally disseminated through the spaces around us : but HERSCHEL's ADJUSTMENT of TELEscopes. 27 the next layer might be explored; and, advancing thus as far as our powers will sustain us, we may yet complete the speculations referred to near the close of the last letter, and talke cognizance of the whole interior structure of the cluster wherein we are. Mean time, however, we will proceed no farther with speculation; and I close this let- ter, therefore, by quoting, in illustration of the above, Herschel's graphic account of his treatment of one of the richest and deepest portions of the Milky Way. He had previously prepared four telescopes in the manner descri- bed—with a series of gaging or sounding powers, ascend- ing in regular progression. He adjusted the finder of his seven-feet telescope to the powers of 2, 3, and 4; to his night-glass he gave space-penetrating powers of 5, 6, 7, and 8; to his seven-feet reflector he gave powers of 9, 10, and upwards, to 17; with his ten-feet reflector he contin- ued the series from 17 to 28; and, thus amply prepared, he undertook to explore a particular spot. “I selected,” says he, “the bright spot in the sword handle of Perseus, as, probably, a protuberant part of the Milky Way in which it is situated. At the time of observation, not a star in it was visible to the naked eye. In the finder, with a power of 2, I saw many stars; and, admitting the eye to reach to stars at the distance of the twelfth order, we may conclude that the small stars which were visible the investigation referred to in the text immediately above, will not be accurately accomplished until we are in possession of an amount of positive information regarding the actual varieties of the stars. There is reason to suppose, that future investigation may remove such doubts; for so soon as we obtain instruments capable of mea- suring the actual distances of the stars from the earth—an achieve- ment perhaps not much above present attainment—we will be able to tell exactly what are the relative sizes of the bodies, within the sphere, whose extreme boundary has been subjected to measure- ment; and, as these may be taken with little admixture of error as representatives of the dimensions of the bodies beyond that sphere, the heavens may be charted, or constructed on the ground of *. IIl- formation they will convey. , Let me emphatically remind you—of what you must never lose sight—that, in the spheres we are track- ing, we are not on the ground of absolute certainty, nor can we at- tempt to fix and define all that is to be found there If we attain a notion of the general forms, or of the shadows of mighty truths, our #. will have its success. To carry into such regions the full ight of reason, to surmount all difficulties, and to clear away all doubts, are reserved for aſter ages. 28 v ARIous PENETRATING Pow ERs. with this low power, are such as to contribute to the brightness of the spot, and that their situation is probably from between the 12th to the 24th order of distances. . . . I then changed the power from 2 to 3, and saw more stars than before, and changing it again from 3 to 4, a still greater number became visible. The situations of these additional stars were consequently between the 24th, 36th, and 48th order of distances. With the gaging power 5 of the might-glass, I saw an increased number of stars; with 6, more stars, and whitishness became visible; with 7, more stars with resolvable whitishness, were seen; and with 8, still more. The stars that now gra- dually made their appearance, thersfore, were probably scattered over the space between the 48th and 96th order of distances. In the seven-feet reflector, with the gaging powers 9 and I0, I saw a great number of new stars; with 11 and 12, a still greater number, and more resolv- able whitishmess; with 13 and 14, the number of visible stars was increased; and so again with 15; and 16 and 17: in addition to the visible stars, there were many too faint to be distinctly perceived.” . And so did the philoso- pher go on—invoking space and summoning up multi- tudes of worlds—through all the powers of the ten-feet telescope, when I find the following entry: “With the whole space-penetrating power of the instrument, which is 28, the extremely faint stars in the field of view obtain- ed more light, and many still fainter suspected whitish spots could not be verified for want of a still higher gag- ing power. The stars which filled this field of view were of every various order of telescope magnitudes; and, as appeared by these observations, were probably scattered over a space extending from the 204th to the 344th order of distances.” (30) LE T T E R -I II. * AsPECTs, FoRMs, AND DISTANCES OF REMOTE CLUSTERS. We resume our progress. The fact has been already established of the existence of vast clusters distinct from ours, sustaining an independent position, as individual constituents of creation. Let us now go forth into infinity among these firmaments and ascertain their character. The number of such masses is very great. In the northern hemisphere, after making all allowances, those whose places are fixed cannot be fewer than between one and two thousand; and you will have a good idea how plentifully they are distributed, by remarking that this is at least equal to the whole number of stars which the naked eye may perceive in any ordinary night. These clusters, the general aspects of which I am now to de- scribe, have very various appearances to the telescope. In many of them, individual stars are distinctly defined. As they become more remote, the distances or intervals between the stars diminish, the light also growing fainter; in their faintest stellar aspect, they may be compared to a handful of fine sparkling sand; or, as it is aptly termed, star-dust ; and beyond this we see no stars, but only a streak or patch of milky light, like the unresolved por- tions of our own surrounding zone. This is the state in which they are more properly called Nebulae, and in which there is risk of confounding them with a singular substance not partaking of the nature of stars, but very common in our firmament. It was in reference to this substance, that I spoke of allowance to be made before estimating the number of known clusters. It has not yet been distinguished or separated in many cases from re- * 30 FORMS OF CI, USTERS OF STARS. note and unresolved clusters; a circumstance much to be regretted, the more especially as principles exist by which an approximate determination might, without difficulty, be attained. - In my first letter I drew your attention to that splendid object in the constellation Hercules, represented in Plate I. Look at it again, and imagine its magnificence. This cluster, in respect of its leading characteristics, is a good specimen object, as it is a representative, or type, of a very large class. Notwithtsanding the partial ilregularity of its outline, it seems almost a spherical mass, in which— with a degree of greater compression probably towards the centre—the stars are pretty equably and regularly diſ. fused; so that, to the inhabitants of worlds near its cen- tral regions, its sky would spangle uniformly all around and present no phenomenon like the Milky Way in ours. In plates V, and VI, are representations of a few more of these spherical clusters, some of which, however, show decided and great compression about the centre; a cir- cumstance which would manifestly much augment the proportionate number of orbs of the first magnitude, in view of those living within the compressed portion, and thus render their visible heavens inconceivably brilliant. The same plates exhibit the degrees of distinctness with which these clusters appear to us. One of the figures in Plate VI, Fig 3, you will observe, is a very faint object, placed near the outermost verge of the sphere within which our mightiest instruments can descry individual stars; it is already in the condition of star-dust, almost ſading into an irresolvable nebula. Clusters, however, are by no means confined to the sphorical form. Our own, and its curious cognate, are exceptions you already recognise, and there are many other equally remarkable shapes. The left hand figure of the upper line of Plate VI. Fig. 1, represents a very singular form (30 Doradus,) sketched by Mr. Dunlop at Paramatta ; and we are just given to understand that it is still stranger than it here appears. Sir John Herschel, whose return from the Cape of Good Hope, laden with spoils, all Europe is anxiously expecting, has recently written as follows, concerning those Magellanic clouds PL.V. Pi \ . . ForMs of clustERS AND NEBULE. 31 which have been long regarded as the wonders of the Southern skies. “The Nebecula Major and Minor are very extraordinary objects. The greater” (see Plate VII. where it is represented from Dunlop) “is a congeries of clusters of irregular form, globular clusters and nebulae of various magnitudes and degrees of condensation, among which is interspersed a large portion of irresolvable ne- bulae, which may be, and probably is, star-dust, but which the power of the twenty feet telescope shows only as a general illumination of the field of view, forming a |bright ground on which the other objects are scattered. Some of the objects in it are of very singular and incom- prehensible forms; the chiefone especially (30 Doradus.) which consists of a number of loops united in a kind of clear centre or knot, like a bunch of ribbons, disposed in what is called a true-love's knot There is no part of the heavens where so many nebulae and clusters are crowded into so small a space as in this ‘cloud.’ The Nebecula Junior is a much less striking object. It abounds more in irresolvable nebulous light; but the nebulae, and clusters in it are fewer and fainter, though immediately joining it is one of the richest and most magnificent globular clusters in the hemisphere (47 Tou- cani).” Fancy a firmament shaped like a lover's knot; and, what is more, a group of firmaments manifestly re- lated . The assertion is assuredly warranted, that when this astronomer is restored to England, we shall obtain a wider extension of our knowledge of the general universe, than has befallen since the time of his great father's dis- coveries. But, perhaps it is when we arrive among the almost bewildering multitudes of unresolved systems, that we are most forcibly struck by the variations of their fantastic shapes. The unresolved clusters being at depths much profounder than the sites of the others, the sphere appro- priated to them is of course of larger radius, and far more capacious; so that there is room for greater numbers, and also a more wonderful display of variety. Plate VIII. exhibits a few of these curious shapes. The annular form is sometimes met with, one fine instance is in the constellation LYRA. The oblong sharp hoop represented 3 32 AN NULAR SYSTEM. in the plate, (fig. 1) is probably a large ring, appearing sharp only in consequence of its oblique position towards us. How utterly different from ours must be the aspects of the sky to the inhabitants of such a firmament The space within the ring is nearly a blank, but not perfectly so, a very thin shade of light spreading over it; so that if any intelligent eye looks from within the space upon what it may well consider its universe, there will be nearly an utter blank towards its sides, and engirdling it round, a zone of the most dazzling lustre. Perhaps the most peculiar of all, however, is that largest object in the Plate referred too, Fig. 2. It has the shape of an hour- glass, or dumb-bell; the two connected hemispheres, as well as the connecting isthmus, being bright and beauti- ful, manifesting a dense collection of stars in those re- gions; while the oval is completed by two spaces, which do not transmit a greater quantity of light, or indicate the presence of a larger number of stars, than the compara- tively vacant interior of one of the annuli. We are lost in mute astonishment at these endless diversities of char- acter and contour. They indicate, -among the Forms of these remote regions, a variety as great as that which distinguishes the minute things around us. Not im- probably it is one aim of the stupendous System of Evo- lution, of which creation as it exists is only one phase, to develope all possible variety, to exhibit how, without in- fraction of steadfast law, Being may be infinitely diversi- fied, and room found for unfolding the whole riches of the Almighty. It was indeed a bold conception, after having recogni- sed the meaning of these dim lights and created them into magnificent firmaments — an achievement which would have filled and engrossed most men—to undel- take, besides, to compute their relative distances and to lay down their plan. But, undaunted even by the idea of a chart of the firmamental universe, Herschel under- took to define that portion within reach of his telescopes, and thereby to indicate what it might be beyond them. The principles referred to near the close of the last let- ter, apply at once—although subject to future modifica- PLVIII. fMMENSE DISTANCE OF CLUSTERs. 33 tion—to the inquiry now opened. The power of a tele- scope, it will be remembered, can always be compared with the human eye, as we know the reach of the eye, so we know the reach of the telescope; and if that power be observed which first descries a star, a simple calcula- tion will inform us, in terms of the general distances of the stars, how remote the object is. To ascertain the distance of a cluster, then, note the space-penetrating power of the instrument which first succeeds in revealing Žts distinct stars, and twelve times that power will be an approximation to the required distance. Herschel, by using comparatively small telescopes, thus fixes the re- moteness of forty-seven resolvable clusters—ten of which were upwards of nine hundred times more distant than Sirius. Plate IX, represents this chart, with the dis- tances affixed.” By larger instruments the determina- tions might be greatly extended; but, though the fields are white, the laborers have been few.—Inasmuch as the element by which the distance is fixed, is the resolvability of the cluster: we cannot come, except by guess, at any conception of the profundities of the milky or nebulous firmaments. A vague guess, however, may be hazarded. How far away, for instance, would the clusters, whose depths we know, require to be removed, in order to look as mere streaks, and to baffle the powers of the best tele- scope 7 Suppose that a cluster, ascertained as above to be of the 900th order of distances, were first seen as a whitish speck by a telescope, whose space-penetrating power is 10, it is easy to calculate how far off it must be to be first descried as a faint spot by an instrument whose power is 200. It would evidently be just 20 times far- ther removed from us, or at the enormous remoteness of 18,000 times the distance of Sirius. Many unresolved clusters are undoubtedly as profound, and very many still profounder in space. Calculating from the sº of a few known clusters, Herschel reaches the depth of the 35,175th Order of distances, in which some of these me- bulae must lie - * Of course this is a mere chart in section of these clusters. They do not lie in one plane, and therefore cannot be otherwise represent- ed than in Section. It is now very imperfect and incomplete; never- theless it will be interesting. The circles indicate the distances. 34 Bound LEss INFINITY—Col.BRIDGE's IDEA. And is even this—the UNIVERSE 7 Where are we, aſter all, but in the centre of a sphere, whose circumfer- ence is 35,000 times as far from us as Sirius—and be- yond whose circuit, Infinity, boundless Infinity, stretches unfathomed as ever ? We have made a step, indeed, but perhaps only towards an acquaintance with a new order of infinitesimals. In our first conceptions, the distance of the earth from the sun is a quantity almost infinite;— compare it with the intervals between the fixed stars, and it becomes no quantity at all, but only an infinitesimal; and now, when the spaces between the stars are contrast- ed with the gulfs of dark space separating firmaments, they absolutely vanish below us. Can the whole firma- mental Creation in its turn be only a corner of some mightier scheme—a larger edition, so to speak, of such a group as composes the Nebecula Major of the South— a mere Nebula itself? Probably ColeRIDGE is not in error —“It is surely not impossible that to some infinitely superior Being the whole universe may be as one plain— the distance between planet and planet being only as the pores in a grain of sand, and the spaces between system and system no greater than the intervals between one grain and the grain adjacent t” But let us not go on to bewilderment. Apart from considerations of Space and Time, we know this fact, that we are in the midst of Being, whose amount, perhaps, we cannot estimate, but which is yet all so exquisitely related, that the perfection of its parts has no dependence upon their magnitude,-of Being, within whose august bosom the little ant has its home, secure as the path of the most splendid star, and whosq mightiest intervals— if Infinite Power has built up its framework—Infinite Mercy and Infinite Love glowingly fill, and give all things warmth and lustre and life—the sense of the pre- sence of God! P A R T II. THE PRINCIPLE OF THE VITALITY, OR OF THE INTERNAL MECHANISM OF THE STELLAR CLUSTER.S. LETTER IV. PROBABLE UNIVERSALITY OF PI, ANETARY SYSTEMS- RELATION OF NEIGHBORING STARs To EACH oth ER —OPENING OF THE QUESTION. RETURNING homeward, through those profound abys- ses, to whose extremities we have adventured, and leisure- ly surveying the objects whose number and varieties struck us at first with an absorbing and most natural astonish- ment, we soon start the inquiry, What are these clusters doing?—What is their internal condition?—What their “sº mechanisms?—And why are they located as they are : It is manifest, that such investigations, in so far as we would rest them on observation, must begin at least with our own cluster;-the telescope, which has revealed the dim lustre of others, having only discriminated their out- ward forms, and still failing to distinguish the peculiari- ties of their individual orbs; but if we analyze the system of which we form a part, and become familiar with the mode of its existence, a cautious use of the argument from analogy, will perhaps darkly illumine- the obscurer ob- jects which surround it. I. In the first place, it is of importance to ascertain whe- ther the stars are individually characterised by the same leading features; or—taking our SUN, which we know best, as a pattern object—whether, and how far, the dis. tinct orbs of remote space may be supposed to resemble him 2 The old notion that these luminaries are of no 3* * > 36 WARIA BLE STARS. significancy, except as ornaments to the earth, has lost hold, I believe, of all classes of minds; so that, assuming what the preliminary astronomy has taught us—that the stars are also sums, shining like our luminary, of their own perennial virtue—we may step at once to a consider- ation of a new, or next higher, point of probable resem- blance. It is singular, that the first class of stellar changes, by which the attention of astronomers was ar- rested, seems to refer to one interesting relationship, the consequences of which extend farther than at first sight appears. A number of stars have long been known to vary in lustre—increasing to a certain degree of bright- ness, and then waning to a certain degree of faintness—a variation found to be periodical, i. e. it takes place regu- larly, and within a definite time. The star ALGOL, for instance, varies regularly from the second to the fourth magnitude, and again back to the highest brightness in about two days, twenty-one hours; the second star in the Lyre, goes through a periodic variation in six days nine hours; a star in the Swan varies from the sixth magni- tude to absolute invisibility, and from that resumes its ori- ginal brightness in eighteen years; and the following table exhibits the course of similar changes in others of the celestial bodies:* Degrees of Names of stars, Periods of Variation. Variation of Magnitude. Days. Hrs. Min. Č Cephei . . . . . . . . 5 8 37 3.4 5 m Antinous . . . . . . * 7 4 15 3.4 4.5 a Herculis. . . . . . . 60 6 0 3 4 o Ceti. . . . . . . . . . © 334 21 0 2 0 x Cygni. . . . . . . . . 396 0 0 6 11 367 #. e e º e º e º º 494. 0 0 4 | 420 Leonis. . . . . . . - K Sagittarii.... Several years. }} 6 p Leonis.... . . . . . 6 0 * I am not certain whether another phenomenon ought not to be ranked with these variable stars. We have now seven or eight au- thentic records of the sudden appearance, and subsequent extinction of new and brilliant fived stars—splendid orbs bursting from the bo- som of infinity, and after blazing for awhile, retiring slowly into their NEW AND ID OUBLE STARS, 37 This variation has also been recently much observed in a number of stars in the immediate neighborhood of each other—so near, indeed, that the naked eye mistakes them for one single star—whence their usual designation, viz. the Double Stars. In a very striking object of this description—y Virginis, whose constituents are equal at certain epochs, there seems a periodical variation in the light of each star, as if each in turn presented a dimmer face to us, or was alternately obscured by intervening opaque bodies. There are at least 23 similar conjoint bodies in which such variations appear; and of these, besides y Virginis, I must especially note e Arietis, ; Pootis; 38 Geminorum ; 48 Cancri, &c. Variation ls suspected in upwards of 40 others, so that the pheno- menon is by no means a peculiar or limited one, but con- nected, in all probability, with important arrangements in the economy of our firmament. unknown remoteness. This phenomenon has once or twice been manifested so suddenly, as to strike the eye even of the multitude. One of the most remarkable instances occurred to Tycho, the illus- trious Dane. On the 11th November, 1572, as he was walking through the fields, he was astonished to observe a new star in the constellation Cassiopeia, beaming with a radiance quite unwontcd in that part of the Heavens. Suspecting some disease or delusion about his eyes, he went up to a group of peasants to ascertain if they saw it, and found them gazing at it with as much astonishment as him- -self. He went to his instruments, and fixed its place, from which it never afterwards appeared to deviate. For some time it increascd in brightness—greatly surpassed Sirius in lustre, and even Jupiter; it was seen by good eyes even in the day-time, a thing which happens only to Venus under most favorable circumstances; and at night it pierced through clouds which obscured the rest of the stars. After reaching its greatest brightness, it again diminished, passed through all degrees of visible magnitude, and finally disappeared. Some years after, a phenomenon equally imposing took place in another part of the Heavens, manifesting precisely the same succession of appear- ances. We are quite baffled to account for these astonishing dis- plays. If the boi. in question are moving in orbits, how singular, that no change of position was observable, and how tremendous the velocity which could sweep these suns in so brief an interval from a region comparatively close to us, to the invisible depths of the Hea- vens !. Some ground of probability is furnished by a comparison of records, that the star seen by Tycho is not a stranger, but one which appeared before, passing through its mighty phasis in about three hundred years' If this be true, it ought to reappear in forty or fifty years from the present date, when, by due study, something concern- ing the yet strange system of phenomena it exemplifies, will proba- bly be brought to light. 28 MEANING OF WARIABLE STARS. Discarding every hypothesis which rests upon no ana- logy with known facts and changes, there are only two accessible explanations of these still mysterious and little- explored changes. Inasmuch as the position of these stars in the Heavens is wholly unaltered during their re- curring changes, we cannot rationally attribute to them an orbitual motion, or explain their varying brightness by varying distance; so that we are reduced to an obvious alternative.” Either, as already hinted, dark bodies of con- siderable magnitude revolve around them, and by their periodical intervention intercept part of their light; or the orbs themselves rotate on axes, and at equal intervals turn towards our solar sphere parts of their surfaces which may be covered with spots, or are otherwise dim- mer than the rest. The former hypothesis is captivating, for it would establish at once the reality of other planet- ary systems upon a scale surpassingly grand; but the very grandeur of this scale, the relative magnitude with which it would require the subservient bodies to be en- dowed, militates against our best notions of planetary cos- mogony; neither does the rigorous periodicity of the variations agree with this motion,-for the intervention of the planets or dark bodies would not in such a case be regular or periodical. The second hypothesis, on the contrary, is in close accordance with established attributes of our own Sun. His disc, owing to the varying number of its spots, gives out varying lights; and you will find, in works which enter largely on the question of the phe- nomena of the solar system, the statement of several grounds of belief, that, besides this periodic variation, there may be an inequality in the illuminating power of the two hemispheres of his disc—the one being percepti- bly fainter than the other. Now, such being supposed, the sun must appear to remote bodies as a variable star— his variation being a strict consequence of his rotation on his axis; so that the analogy of his constitution clearly favors the hypothesis, that the variation of other stars is referrible to similar peculiaritics of constitution, joined to the fact, that they RotATE likewise. Our reasoning is also identical with what is esteemed quite adequate to establish the rotations and periods of some of the satellites R OTATION IN FERS PLANETS. 39 belonging to the more distant planets of our own sysem. Too distant to exhibit small individual spots on their sur- faces, these yet show a general variation in the light of the discs they alternately present to the earth; and the varying light, whatever its cause, is supposed to deñon- strate this alternation of their visible surfaces. At the outset, them, we have reached the conclusion, that the rotation of the sun upon his axis is no isolated phenomena, but one partaken of by vast numbers of the other orbs, and indicated by unequivocal appearances; but there is a secondary inference which bestows far higher importance on the tidings sent from these variable stars. Phenomena apparently the most distant are often closely related in the grand scheme of things; and—as you will learn afterwards—the rotation of an orb, and the existence of engirdling planets, are so closely con- nected, that the planets may be said to spring out of the circumstance of rotation 1 the existence of planets indeed may be almost predicated of every case where rotation is detected. This new problem, however, may soon be withdrawn from the region of surmise, and resolved in separate instances, by the Telescope. Sir John Herschel— a mere hint from whom is of authority—has lately re- quested attention, in the most express way, to the minute and point-like companions of such stars as URSAE, * CAPRIcorn 1, a CAN cR1, y HYDRAE, , GEMINoruM, &c., as in some of the cases probably shining by reflected light. If these small silvery points—lurking within the rays of their respective sums, should indeed prove to be planets, the telescope will have performed the greatest of its achievements; and if, upheld by observation as far as it can stretch, our knowledge of the physical constitution of matter will ever enable us to state it as a general and, necessary law, that all the orbs of space—not merely those which shine above us, but also the myriads whose wonderful clustering is seen in distant firmaments—that each one of this mighty throng, is, through the insepara- ble exigencies of its being, engirt by a scheme of worlds— proud as ours, perhaps far prouder; how immeasurable the rangel how illiluitable the variety of planetary exist- 40 EXTENT OF PI, A NETS-SU NS RELATED. ence | No wonder that our small world—a mere nook in space, an infinitesimal item of that mighty whole— should be incomplete and fragmentary, silent concerning the interior of many phenomena which are developed in it, and containing few illustrations of much we desire to know of the fundamental conditions of Being. The Great Book of the Universe—that which explains the labyrinth and leaves no enigma—deduces its easy expositions from the perfect Universe: the few stray leaves of this book which have reached terrestrial shores, must seem sybil- line, often incoherent—speaking of laws which enter among visible arrangements only by their lateral actions, and whose roots are down, far from present sight—deep in the bosom of that all-encompassing Wisdom which comprehends the entire system of things. II. Having obtained this gleam of evidence—albeit nearly evanescent—that the sums of space are also the central luminaries of great planetary trains, we drop for the moment all thought of planets, and proceed with the more daring questions:—Are the different suns isolated or related ? Does our sun, and every other orb, retain its place, its constitution and character, independently of its neighbour? Or, as with minor arrangements, is there here also, even in the great vault, some intimate connexion, some network whose refined tracery may be pursued? . A train of discovery has followed from these inquiries, which might be the distinction of an epoch, and which constitutes the proudest title of ours to be ever illustrious in Astronomy. I shall unfold the subject by ascending through the different orders of known relationship. It has been observed, at least since the time of Galileo, that, while the great majority of the stars in the Heavens appear somewhat equally distributed, and therefore at medium or average distances from each other; there is a large class which exhibits peculiarity of arrangement in. this respect, evincing a greater degree of proximity than the hypothesis of equal scattering will account for. The more remarkable of these neighbouring stars are so close, that they cannot be separated by the naked eye, but ap- PROXIMINITY OF STARS. 41 pear as a single star, until analyzed and divided by good telescopes;* and to such objects, about the close of the last century, Sir William Herschel happened to give especial attention, in the hope of resolving by their means, the pro- blem which proposes to determine the distance of the stars, by noting the amount of their apparent displace- ment, when viewed from opposite ends of the Earth's orbit. At that time the unusual proximity of such bodies was accounted for by supposing that they lie in almost the same visual line, or that their apparent proximity is opti- cal, not real; one star being imagined far behind the other, and divided from it by not less than the wonted in- terval—but seen as nearly in union with it, because the two are in very nearly the same direction. In his earlier papers, Herschel assented to this hypothesis, but he quick- ly discerned its fallacy, and foreboded in these stars a sig- mificancy far more profound, which he afterwards evolved by a process of ratiocinative observation of the most preg- mant kind, and which is still one of our most brilliant ex- amples of philosophic inquiry into the remote unknown. Knowing the approximate number of stars belonging to each magnitude, it is easy to see that we may calculate , also approximately how many, or at least what propor- tionate number of the whole, should be placed—the one so nearly behind the other, that both stars would appear to the observer as if within a certain distance of each other in space. Were there, for instance, in existence only fifty, or a hundred, or a thousand, of these celestial bodies, placed at different depths in space, it is clear they would seem strewn over the surface of the skies very sparsely, and by no chance could one be expected to be immediate- * These objects are exceedingly beautiful; and, fortunately, some of them may be decomposed by télescopes of ordlnary power. There is one in the constellation of the Great Bear, which a common glass will separate; it is the star . Even to the naked eye & appears dou- * *k + .* & * * **, *: #: - - - . . .” ble, but that is not the phenomenon. It is ºrger of the two, which may be decomposed, and to which I refer you. 42 APPARENT POSITION AND ARRANGEMENT, ly or even nearly behind another. Augment the number of stars as far as that recorded in our maps, and the probability of one or more cases of optical proximity will unquestionably be increased; but if they are less nume- rous than would render large apparent intervals between individuals uncommon—which only happens in the Milky Way—the occurrence of these optical conjunctions must still be comparatively rare. But the apparent conjunc- tions I refer to, are not rare; on the contrary, they are very numerous. The telescope reveals vast numbers of shining bodies in each other's immediate proximity; and since that cannot be accounted for by supposing that the proximity is merely optical, or that it arises from the fact of one star fortuitously lying far behind the other, and nearly in its visual line, we are constrained to infer some new law, some ARRANGEMENT among classes of stars, distinguished in all likelihood by phenomena formerly unknown, and of which this unexpected proximity is the internal index.” From this brief explanation, it is manifest that we are approaching arrangements different from any thing pre- viously detected in the heavens; and the probable extent of the field to which the discovery so opened will intro- * The argument may be familiarly illustrated as follows:—Sup- pose a number of peas were thrown at random on a chessboard, what would you expect? Certainly, that they should be found oc- cupying irregular or random positions; and if, contrary to this, the were, in far more than average numbers, arranged by tvos on eac square, it would be a most natural inference that here there was no RANDOM scattering; for the excessive prevalence of the binary ar- rangement would indicate forethought, design, system. “Casual situations,” says Herschel, on the strength of the principle thus illustrated, “will not account for these multiplied phenomena; and consequently their existence must be owing to some general law of nature. Now,” he continues, “as the mutual gravitation of bodies towards each other is quite sufficient to account for the union of two stars, we are authorized to ascribe such combinations to that princi- ple.” You perceive he has at once reached the fact, that a double star is not always one star seen behind the other, but for the most part two stars seen in actual proximity—in systematic and regulated wnion ; and, in the fullest confidence in that of DER which pervades all Nature; where every arrangement has a cause and meaning, he has also asserted that this union subsists through energy ef some eneral law. We shall soon see that it needed little more to enable im to foreshadow a memorable truth. VALUE OF SPACES SEPARATING STARS, 43 duce us, may be ascertained by a few calculations, which I will arrange in tables. They represent the actual num- bers of stars found in close proximity, and contrast them with the very few which might be expected to be only optically conjoined. First, however, let us attain some easy but clear notice of the amount of the small quantities of which I am about to speak. If the whole circuit of the heavens were divided into 360 equal parts, each of these parts would be termed a degree. If one of these degrees were sub- divided into 60 equal parts, each of these parts would be what is termed a minute ; and if a minute were again subdivided into 60 equal parts, each of these very small parts would be a second Now, the distances we have to deal with are expressed in seconds, and they are so small that it will cost you no little difficulty to apprehend their real or comparative sizes. One fact may be of as- sistance. The diameter or breadth of the sun is nearly 2000 seconds, so that if we suppose that breadth, as it appears to the eye, to be divided into 2000 equal parts, one of these parts will be about the size of one second, two of them that of two seconds, &c.” For the sake of convenience, the approximate or con- joint stars are divided into orders, determined by the dis- tance of their constituents. The first eight orders include all bodies within 32 seconds of each other, i. e. not sepa- rated from each other by so much as the apparent breadth or diameter of the planet Jupiter. These are essentially double stars, i. e. they appear single to the naked eye, nor can the closest of them be separated without the aid of the finest telescope that art has yet produced.—The sub- sequent tables will now, I hope, be understood without difficulty. The one first presented contains all the double stars, from the Pole to 15° south of the Equator, in which neither constituent is very much less than the least we can discern with the naked eye; they should be easily seen, at all events, with a good common telescope. From the care bestowed in the survey, this list must include * Degrees, minutes, and seconds, are usually written symbolical- ly.—Thus 10° 11’ 12”, signifies ten degrees eleven minutes twelve sºconds, 4 44 NUMBER OF PROXIMATE STARS, about the whole of such objects to be found in these re- gions of the Heavens TABLE I. Nº. º º: 9. º & ably only Numb two former (ols. orders | Distances ºilº distance. Imate StarS. I. O’’ to 1''' .06 62 |* ~ 62 II. 1 to 2 .14 116 116 , III. 2 to 4 .56 133 132 VI. 4 to 8 2.24 17 128 V. 8 to 12 3.73 54 50 VI. 12 to 16 5.23 52 47 VII. | 16 to 24 14.94 54 39 VIII. 24 to 32 20.91 52 31 Sums, 48 653 605 From this table we deduce the important fact, that so far from the principle that these conjunct stars are opti- cally double—i. e. that they appear near, because of the sameness of the directions in which they lie—so far from that principle being able to explain the whole existing arrangements, it accounts for the proximity of no more than 48 sets out of 653—leaving 605 to be explained by some other law, and to stand forth, as they emphatically did to the philosophic mind of Herschel, the indices of unknown and profound design The next table refers to stars whose small companions are of much less mag- nitude, and of course only includes those of which we have akready complete lists. The distances corresponding with the orders are the same as above. TABLE II. Orders. Numºrically Num º ob. Nunººgally I. 1. 16 15 II. - 3 82 79 III. 11 176 165 IV. 43 214 71 . V. 71 124 36 sums, 129 612 483 PROX IMATE STARS–G ENERAL LAW. 45 In other words, of 612 conjunctions among the smaller and more numerous stars, there are 483 unaccounted for by the notion that the proximity only indicates that one star is far behind another. STRUVE, in the introduction to the Catalogue from which we derive our details, has pursued the inquiry to its apparent limits—i.e. until he reaches the distance at which the probability of the con- junction being solely optical, undoubtedly prevails. The following table, containing complete lists of the brighter stars only, gives his conclusions. Numbers pro Numbers|Number; Phy- Orders, Dist - babl i- icall * | * ºbserved ºff IX. 32” to 60"| 1,536 | 15 13 X. 60 to 120 6,439 15 9 XI. 120 to 300 7.74 17 9 XII. 300 to 600 || 27.56 38 10 XIII. 600 to 900 21.50 25 - 3.5 Sums, 65 110 || 44 It cannot fail to be noticed that the number of stars optically related is much larger than in the former table; and in order XIII, nearly the whole are related optical- ly; thus evincing that the limit 15' or 900" approaches to the usual or average interval of celestial space between independent stars of the magnitude referred to. The re- sult of the whole may be briefly stated:—In reference to stars not smaller than the least we see with the naked eye, there is a possibility of the eacistence of a certain unea- plained connection or relationship wherever the distance is within 15', or about half the diameter or breadth of the sun ; when the distance is less than 5’ or one-sixth of the breadth of the sun, the probability of such a connection is very considerable, and in almost every instance, whether the stars be large or small, where the distanee is less than 30" that connection may be predicalled with an approach to certainly as near as ca/º be attained on subjects so speculative. If the word speculative is right- ly interpreted as fanciful or hypothetical, I am in error in thus using it; for the foregoing conclusions are as 46 HERscHEL's con JECTUREs of TRUTH." sound and warrantable as if they rested on a long induc- tion of actual and known connections. The character of the specific connection we may not, on grounds yet unfolded, venture to assign; but that a connection exists, far spreading and memorable, constituting an important feature among the complex arrangements of our firma- ment, is sustained by that maxim, which is at the root of all philosophy—that Nature is not capricious, and that analogies, or correspondences, stedfastly indicate some Law, real though unrevealed. It is from the confidence with which he rests on this belief—one inseparable from his being—that the true philosopher derives his powers as a seer. The analogy or group of collocated events, is the bud of mighty truth, whose growth or fulness he descries from afar; and he proclaims in words of pro- phecy its approaching advent. - The force of considerations like the foregoing was not lost upon Herschel. Of all men—with perhaps one exception—who ever adventured into unknown regions of the Heavens, this great Inquirer was most deeply pe- netrated with an enduring conviction of the all-prevalence of Law, whose characters were first indicated by “collo- cations;” and he evinced a marvellous quickness and solidity of judgment in interpreting the remotest hints, a feature, a single line was enough, and he divined the outline of the portrait. Rising, in the present instance, to the utmost height of justifiable speculation, he inquired if g avity, a law already known, would not account for the connection which seemed established, and whether, in such a case, the Suns would not, like other planets about their Central Luminary, revolve around each other in definite orbits? Herschel, however, was too sound a phi- losopher to be withdrawn, even by the fascinations of so brilliant a conjecture, from that laborious path which alone can guide to truth; and at the same moment in which he threw out his ideas, he urged Astronomers to confirm or disprove them by observation; thereby exhi- biting labors of his own by which, if extended and re- peated after long intervals, all mystery would be with- drawn from these singular bodies. Nor did he summon DISCOVER HES OF OTHER ASTRONOMERS. 47 unwilling laborers. I can compare the sensation occa- sioned in the astronomical world by his discoveries, to nothing save the excitement diffused through Europe when Columbus discovered in the far west new and mighty continents resting amid the formerly void and mysterious ocean. To follow up his examinations has constituted probably the chief ambition of observers from that time until now. Observatories, with gorgeous ap- pliances, have been carefully suited to that specific pur. pose; and many private observers have, with their utmost means, toiled in the same walk. Before the close of his earthly honors, the veteran had himself accomplished the measurements; that is, had fixed the places of above 500 double stars. In 1824, Sir JAMEs SouTH and Sir JoFIN HERscHEL produced a catalogue of 380 stars, whose distances and angles of position they had jointly fixed with admirable precision. South followed it up by a dis- tinct catalogue of 480; and Herschel, now also observing apart, has completed a list of upwards of 3300 of such determinations. Inferior to none, however, is M. STRUVE of Dorpat, who, aided by that noble instrument, the Equatorial of Frauenhoffer, first analyzed and afterwards measured the positions of nearly 3000 double stars, with a precision that cannot be surpassed. His last work, which reached this country only a few months since, is thus at once the latest and the classical work on the sub- ject of the motions referred to.—These catalogues, how- ever, do not reach farther than 15° south of the Equator, so that the entire southern hemisphere may be still reck- oned a blank—but one destincă to be speedily filled, for Herschel has garnered its riches, and will soon convey them to Europe. Nothing was known previously, con- cerning the double systems of that vast celestial space, except a small catalogue by Mr. DUNLop of Paramatta. Allusion to this remote observatory forbids me to pass the name of its founder—himself an able and laborious observer, Sir THOMAS MAKDoug AL BRISBANE; through whose munificence it was established, and British science made co-extensive with British dominion. Gracefully does the laurel due to such actions adorn the green au- tumn of lifel - , / 4* 48 MODE OF OR SERVING.. " My readers will now be prepared to follow the steps of positive discovery in this new and attractive sphere. Astronomers, I have said, undertook to examine and re- cord the relative positions of the stars presumed to be connected, so that they might be compared with distant records made at other epochs. The mode of recording the position is simple. Suppose that a circle with cross diameters, such as the following, were placed in the eye- piece of a telescope; that is, so placed that both it and the stars should be visible at one and the same time. o o of A sºo 640 ° Suppose also that its circumference were divided into 369 equal parts, viz. degrees, beginning at 0°, and pass- ing through 00°, 180°, 270°, to 0°, or 360° again, and let the reckoning proceed without interruption to 450°, 540°, 630°, &c. &c. Now, if one of the asso- ciate stars be brought to the centre A of the cross lines, the other will lie somewhere else. Suppose it to be at B; then draw a line through A and B to meet the circle in C; this line will clearly cut off the part of the circle between 0° and C, which will contain a certain number of the equal parts spoken of; and if that number be known, the exact distance of the point C from 0° ma be laid down in a chart or figure. If B should now change its place relative to A, and, after a certain length of time, occupy the place B', this change would be imme- diately detected by an observer, who would find that the line AC’ through A and B'now cut off a greater number a URSA, MAJoRIs. 49 of those equal parts, on a larger part 0°C of the circle than formerly. And thus, by noticing carefully the num- ber of degrees, or of equal parts of the circle cut off at all times by the line through the centre of the two stars, their relative changes of position might be clearly ascer- tained. The distances of the stars; that is, the lines AB, AB' might also be carefully measured, and their varieties recorded. To effect such measurements requires the finest instruments, but art is equal to the task of pro- ducing them. The error of the instrument is very rarely so great as the error of the observer in using it. The instance of ; URSE MAJ or Is will illustrate this method of observing, and exhibit an actual progress in an associated star. The table below presents the distan- ces of its two stars, measured at different epochs, their angles of position, i. e. the quantity of the circle from 0°, cut off by the line joining their centres at the several epochs, and the names of the observers. We shall expe- & URSIE. Epoch. Portions. | Distance. Observers. 1781.97+| 5039.47° | . . . . Sir William Herschel. 1802,09 || 457 .31 e - © - Do. 1809.08 || 452 .38 * * * * Do. 1819.10 || 284 .33 2”.56 Struve. 1820.13 || 276 .21 tº e º 'º (). 1821.13 268 .48 e e º º - Do. 1822,08 || 262 .39 e tº º e DO. 1823.29 258 .27 || 2 .81 South and Herschel. 1825.22 244 .32 • * ~ * South. 1825.25 * - - - 2 .44 - Do. 1826.20 || 238 .75 || 1 ,74 Struve. 1827.27 228 .27 1 .71 Do. 1829.35 | 213 .59 || 1 .67 Do. 1831.44 203 82 || 1 .70 Do 1832.41 195 .80 || 1 .75 Do. 1833.38 | 188 .24 || 1 ,69 Do. 1834.44 | 184 .10 || 1 ,87 O. 1835,41 | 180 .18 || 1 .76 Do. 1836.44 171 .2 1 .97 Do. * The decimal places after the year in the table, indicate the time of the year, or the date, when the observation was taken. ... For in; stance, 1838 =5 would signify the exact middle of the year 1838, and so of the other parts. 50 § URSE. rience little difficulty in drawing from it the proper and suitable inference. The recorded distances of the two stars are ambiguous, and perhaps contradictory, but they vary within limits so extremely narrow, that much may be referred to the er- ror of observation. The change of the angles of position, however, is manifest; and, as the foregoing remarks will have convinced you, these enable us to ascertain how the two stars were placed with regard to each other at their respective epochs. Without farther reference to tiresome minutiae, I shall express these changes to your eye by a plate. (See Plate X.) The three upper lines contain a representation of the positions of the two stars, as indi- cated by the previous table, at the epochs marked above them. Observe how the smaller star gradually moves around the other in an orbit ! Can any one, on looking at this plate, doubt the reality of the motion of these orbs? Nor is ; Ursae singular. The next two lines represent the positions of the two stars in Castor, which, indeed, vary much more slowly, but are equally indicative of a grand motion of revolution. Lastly, observe the line con- taining the record of the changes of y Virginis;–it af. fords evidence no less emphatic of an alteration of place, intimating orbitual motion; although the period of the stars is still vaster than that of Castor. By means of these diagrams, your reason will be satisfied of the mar- vellous truth, which all recent astronomy has confirmed. I know it requires no trifling amount of evidence to in- duce us to accept a phenomenon so novel and so wonder- ful. If aught in the universe were a landmark, it surely might be supposed to be those stars infinitely remote, deep in peaceful infinity, and undisturbed by the commotions of earth. But, neither have these a fixed place; they also are governed by the omnipotent ordination of Acti- vity; and partake, amid their apparently profound repose, of that course of change to which all the universe is sub- ject, and which presents to the meditative eye the mightiest shows of Being as only transitory—phases of some scheme of unresting and stupendous evolution The question next presses, In, how many of these ap- Pl X . Asºzzoz oºze 2.5ºzzº. 2/ f Ursae Maj oris 222. ºf ./?& 22%22 -º'oZ.9 2.5% 232/.3% 23.26% *** * 22°23’ 23:42.2% 23.36%- Zºszzzzz 2^2%e2.5%ars 2^ Castor 22 ->2/37 22.2% → 25°232. Z3s2/22/2 2/.4%e 2.5/22, 2/** Virginis 272^ 22°.93 23'33" zºº. 243& 22, 29.2% 2*2/2 22*2/2 3%zz. Zºrč/. 2A Arza'icº Zºz Azeezoz. NUMBER OF KNOWN MOTION S. 5 | proximate stars have such motions been recognised; in other words, of what degree of advancement can we boast in this department of observing astronomy 7 We again seek the reply in the pages of M. Struve. The following Table presents the whole double stars whose existence this laborious observer has detected, arranged according to their orders; and the subsequent columns contain the number which have evinced the certainty of a mutual re- lation, by the fact of undoubted change. TABLE III. Number of stars in which Ord aşºilo. changerchangel Áum of rCier. Ul Sl:). TS 2.3 triº ºf or r e each ...” *ge º º Changes. certain bable, pected. I. 91 13 4 3 15 II. 314 10 6 5 15 III. 535 12 5 12 19 IV. 582 7 9 14 17 V.—VI. 583 7 9 I4 17 VII-VIII. | 535 9 6 18 18 Sums, 2640 58 39 66 101 The last column is made up, not by taking the sum of the three preceding it, but by adding to the third column that proportion of the fourth and fifth in which change may be safely assumed. Struve so estimates these obser- vations, that six out of ten in the fourth column, and only three out of ten in the fifth, can be assumed as actual changes. One hundred and one stars out of 2640, are thus all that have yet yielded the secret of the mode of their connection; although our arguments, from their proximity, establish it as indubitable, that, in the im- mense majority of that large number, connection must exist. But, seeing the date of observation is only as yes- terday, let us not repine at the fewness of the motions as- certained, so much as rejoice that a sure promise remains to stimulate the ardour and reward the industry of inqui- rers. It is no more than fifty years since measurements of this kind were first undertaken—not more than thirty- six years since the probability of obitual motion among 52 NUMBER AND CHANGE OF BRIGHT STARS. the suns of space was ascertained by Sir William Her- schel; and then, how slow are many of these motions, how rare and recent the instruments capable of following their evanescent variations, how “envious,” too, are the “clouds” of Man's too intimate knowledge of the Hea- vens ! But notwithstanding every obstacle, we have a right to the highest hopes. Not a year will pass without adding some new systems to our catalogue; and, long before the lapse of a century, perhaps, the motions of few of these 2640 objects will have escaped the vigilence of the telescope. - * - The brighter stars observed by Herschel, i. e., those stars whose measurements were taken at the earlier periods, exhibit the changes indicated in the subjoined table. * TABLE IV. Number of Number of stars in which - order |º ſº dº. Herschel, certain. baj. pected. I. 10 8 0 l 8.3 II. 19 7 4 2 10.0 III. 42 9 4 9 14.1 IV. 44 ... 6 5 '7 | 11.1 V.—VI. 34 2 6 7 7.7 VII.—VIII. 28 3 3 7 6.7 58.1 Sums, 177 35 22 33 This table is very important. First, it exhibits 58 es- tablished systems in a list of 177, which perhaps inti- mates the proportion of the foregoing 2640, or 880 sys- tems, as the least number we may expect to find estab- lished at the end of the next fifty years; for in Herschel's stars there is nothing peculiar, and telescopes are about to be applied to the Heavens, which will bring the small- est bodies, whose positions are now recorded, within the class of bright stars. It is however, remarkable, besides, that the greater number of changes are observed in stars belonging to the first orders;–the very first order, which IN FERENCES. 53 includes objects whose constituents are no farther sepa- rated than one second, yielding 8.3 systems out of 10. This fact can be accounted for only on the supposition, that the stars apparently nearest move with the greatest velosities, and that the velocity diminishes and becomes more difficult of detection as the apparent distance in- creases; and, inasmuch as the planets actually nearest the sun moye with much greater rapidity than those more remote, we infer that the pairs of stars which seem to be nearest are so in reality; and that, with a few exceptions, their comparative proximity is not owing to their remote- mess from our sum. Struve deems the truth now an- nounced of great importance, and he has embodied it in the following proposition:—“The division of the double stars into orders, according to their mean distances, does not rest on mere appearances. Stars of the first order, distant from each other from 0 to 1", are generally those whose actual linear distances from each other are the least; and the same holds good in the case of the other orders. Wherefore, the nearer the stars appear to each other, the more intense is the action of gravity by which they are restrained in conjunction, the more swiftly do they move in orbits around the centre of gravity, and the less are the periods of their revolutions.” It is now time to state in distinct and emphatic terms the grand truth, with which these researches on approxi- mate stars have enriched astronomy I have already un- equivocally shown that the study of these conjunct bodies involves the wonderful phenomenon of one sun revolving around another; and there cannot be a doubt that all the changes whose discovery I have narrated so fully, exhibit the same thing; viz. the motion of one individual of each pair, through a certain part of an orbit. No part of the subject is left in doubt, as at least four systems have com- pleted their courses since observation began, and yielded not only their periods, but the special nature of their orbits.” These ſour are the following: . * The nature of the curves or paths in which the bodies move, es- tablishes an important general truth. At first sight, it seems easy to detect these paths, the problem simply requiring that we set off distances from the central body, corresponding to each angular po- } 54 PERIODS OF REVOLUTION. m CoRoNE . . . . . . revolves in . . . . . . . 43 years. * CANCRI. . . . . . . . “ . . . . . -.. 57 “ & URSE MAJORIs. { { . . . . . . . 61 “ p OPHIUCHI. . . . . . . { { . . . . . . . 80 “ Three more have been watched with sufficient assidu- ity to justify astronomers in assigning their approximate courses, viz. * b CORONE. . . . . . . revolves in . . . . . . . 200 years. CASTOR. . . . . . . . { { . . . . . . . 215 “ y VIRGINIs. . . . . . . {{ . . . . . . . 513. “ Other periods, also, have been conjectured, on grounds sition. Unfortunately, however, we cannot depend upon recorded observations of distance; the slightest error Vitiates the whole, and more than slight errors have been committed in such estimations. For instance, the star p Ophiuchi, would, if so judged, have an orbit like the following, through which no imaginable continuous curve could pass. There is a supreme necessity for the rejection, in toto, of recorded distances, and that reliance be placed on the angles of osition alone. Acting virtually on this plan, SAVARY evolved, by a ong but ingenious analytical process, the orbit of & Ursae, and Pro- fessor ENcKE of Berlin applied similar methods to the case of p Ophi- uchi; but the honor of summarily overcoming the whole difficulty— of giving a general and pliable method, distinguished no less by its facility than by its extreme beauty, by which the required curve may be charted, even from partially erroneous elements—is due to Sir John Herschel. Young geometers, as an exercise of taste, ought to , P WASTN ESS OF THE FIELD. 55 however, more than questionable; nor is the straining of computation, necessary, inasmuch as the foregoing in- stances, distinct and indubitable, establish that general iaw which patient inquiry will yet extend through all the vast classes of conjunct stars. How wide that field of novel contemplation opened by these brilliant discoveries How strange the notion of mighty orbs revolving around each other in less periods than that which Uranus occu- pies in encircling our sun 1 Are these revolving sums also accompanied by planets? The fact of rotation on their axes appears established among many of them, by their periodic variations of light; and if, as before assert- ed, rotation involves the idea of engirdling planets, around these double suns planets will unquestionably roll, obey- ing perhaps both, and drawing from both light and the conditions of their wonderful life It is when one goes into regions so new and remote that the character of the Universe, in its majesty and infinite variety, appears in its most striking attributes. In search of magnificence, it is true, we need not wander far, witness the fields which encircle your home, the blade of modest grass which adorns them; but those Heavens are fresh, and familiarity study his memoir; and cultivators of any department of experimen- tal physics, will find in it sources of unexpected power. The curves, as Sir William Herschel predicted, are elliptical ; i. e. the one star moves round the other, in every case (or, more properly, each around their common centre of gravity), in an oval or elliptic curve— precisely the curve which is described by the Earth and other planets in their revolutions around the Sum : the law of the velocities likewise is the same in both cases. Uniformity of this sort is exceedingly re- markable—it points to some common cause ; in other words, to the LAw of GRAVITATION, which the nature of this curve enabled NEwTon to detect as the first principle of planetary order. Gravity has often been surmised to be universal; at all events, we have now stretched it beyond the limits of the most eccentric comet into the distant in- tervals of space. Every extension of its known efficacy manifestly increases, in accelerating ratio, the probability that it is a fundamen- tal law or principle of matter; but although it should somewhere fail, it is still a type of the mode of the constitution of things;–it will lose its universality only through the preponderating efficacy of still pro- founder powers. Judged in this true light, the vastness of Creation is comprised within a mighty plan ; and we, standing on this little world, can gaze around on its majesty, and notice its stupendous changes in peace—knowing that there is no hazard or caprice in Mutability, but only the stern and steadfast power of Law, through which all events roll onward to their destiny. 5 56 COURSE OF DISCOVERY. w has not left its footprint on their untrodden floor. In the silence of midnight, that noble curtain stretched out above me, and the idea, present and impressive, of its great orbs obediently pursuing their stupendous paths, I confess there is a solemnity which sometimes falls upon the spirit, not unlike the feeling of the Patriarch, when he heard that still small voice, and knew it to be the presence of God! The course of discovery will doubtless greatly enlarge our knowledge of such periods and orbits; though per- haps there may be sufficient similarity in the most of them to render them in a great manner devoid of indi- vidual interest; but from this we must except two classes of stars which promise to afford a subject of very engross- ing contemplation. Struve correctly remarks, that of all the orders, the first is that in which rapid discovery may be most confidently expected, because it is only by tele- scopes now coming into use that stars so very close can be decomposed or measured with requisite accuracy; and, on the ground of the proposition announced at the close of the last paragraph but one, he considers that these very close pairs will yet manifest many instances of revolutions accomplished in much shorter periods than that of even n Coronae, His great work has laid the foundation for large advances in this field; it has already afforded ground of conjecture that ; Herculis has a period not exceeding fourteen years, and that 42 Comae Bere- nices, y Corona, and r Ophiuchi, have likewise very brief periods. While referring to these indications of rapid and restless activity among the most majestic bodies of our firmament, the Astronomer expresses his pious grati- tude that he has had patience and vigor for the pursuit of them, and that his eyesight is unimpaired. It will be the universal wish of Europe that, in the labors of the splen- did Observatory to which his hopes now point, these bless- ings may be preserved to him; and that the fates of Urani. burg may never darken the history of this second instance of the noblest institution the world has seen, dedicated to Astronomy by Imperial munificenceſ The other class I have alluded to, as likely to afford results of singular interest, lies at the opposite extremity MOTIONS OF STARS. 57 of the scale of orders. I have shown that stars so far separated as 15' or 900" from each other, are still with- in the suspicious distance, i. e. that probably a few pairs so situated are physically connected and form systems. This information is of itself so vague, that perhaps few observers would be disposed to watch and measure all 'such stars, in the hope of detecting these few ; but for- tunately another principle enables us to select the actual pairs, to point out many specific sets, of whose connection we are certain, although their motions are yet unrevealed. The principle is this:—A great many stars have what are termed proper motions in space, i. e. they are slowly shifting their places in the sky, moving regularly on- ward by small annual quantities—quantities which vary with the stars—lm what, as yet, appear straight lines, but which doubtless are small portions of vast curves. It happens, that amid all this variety of motion, both the constituents of a great number of stars, optically con- nected, partake equally of such motions; that is, the one star moves annually in the same direction as the other, and by precisely the same quantity; and how infinitely small, how inappreciable is the probability that they would do this were they only optically connected? True, stars may exist separated from each other by gulfs of space, which have proper motions that would appear the same when viewed from the earth; but, considering the immense variety of these motions—how trifling the chance of pairs of such objects being frequently found nearly in the same line ! This chance, rightly estimated, is much smaller than that which depends upon the mere position of the stars; and the conclusion is therefore necessary, that when an identity of proper motion is de- tected, these stars—suspicious on other grounds—are cer- tainly connected physically; their systematic character being the cause of the identity of their proper motion. Now a considerable number, far separated from each other, are thus demonstrated to be systems;-among which I distinguish the following:— - * º a. º constituents distant 72 seconds, 40 ERIDANI, 3. & ſº tº as 84 e; 58 LONG PERIODS. REGULUs,' d • * : ... 180 e and 5 LYRE, • * ... 210 02 and 61 TAURI, e e ... 336 36 OPHIUCHI and ) 720 30 ScoRPII, s & • * - MIZAR and ALCOR, e G ... 720 Between these two last stars, Mizar (; Ursae Majoris). and Alcor, a small star of the 8th magnitude, is interja- cent, which does not partake of their proper motion. It is impossible to reflect on systems constituted by orbs so far apart as these, without expending a moment of wonder on the periods which must be occupied in their revolu- tions. If t Orphiuchi, or ; Herculis, surprise us by their rapidity, and consequent restless activity; systems like the ſoregoing astonish by the durations through which they hurry the imagination. Observation, of course, can alone determine their actual periods, but by a simple artifice we may reach a conception of what they are. By the laws of motion we can calculate what would be the period of any star whose present period and dis- tance we know, were its constituents as far asunder as these others are. Taking p Ophiuchi as our standard, whose present period is 80 years, and its distance 4.”33, we find that if its two stars were separated as far as those in 40 Eridani, their period would occupy more than 7000 years, and that, were they at the distance of Mizar and Alcor, it would stretch over no less than 190,000 years Such, then, or some such, is the period in which Mizar revolves around Alcor, a period which is the unit, the single year, of that stupendous system Our small units, one hundred and ninety thousand of which are thus com- pressed into one single unit of a vast system, may serve to reckon the days and months of human life—the dura- tion of royal houses—the periods of empire; to measure the surface-changes even of our own globe, they have been found inadequate—how, then, shall we extend them to the skies, and attempt to read by their puny aid those celestial annals, which must be divided according to numbers of their own 2 - I have lingered not unwillingly among these gorgeous color of THE STARs. 59 fields, but the space already occupied warns me that it is fitting to close. One other point, however, connected with these pairs of sums, is so singular, that I anticipate your ardon, though you are detained a moment longer—I al- i. to their color. It has long been observed that the stars shine with different colors; for the diversity is ap- parent to the naked eye. Among those of the first mag- nitude, for instance, Sirius, Vega, Altair, Spica, are white, Aldebaran, Arcturus, Betelgeux, red, Capella and Proc- yon, yellow. In minor stars the difference is not so per- ceptible to the eye, but the telescope exhibts it with equal distinctness. It is likewise far more striking in countries where the atmosphere is less humid and hazy than ours; in Syria, for instance, one star shines like an emerald, another as a ruby, and the whole Heavens sparkle as with various gems.” Now, this attribute of variety of colour distinguishes also the double stars, which, indeed, was to be expected; but the association of these colors presents a new and remarkable phenomenon. Struve re- cords that, in at least 104 binary systems, the two stars exhibit the complementary colors, that is, the color of one constituent belongs to the red or least refrangible end of the spectrum, while that of the other belongs to the violet or most refrangible extremity, as if the entire spectrum had been divided into two parts and distributed between these two companions.f An opinion prevailed lately that this phenomenon is the mere effect of contrast, or of an optical delusion depending upon the well known law that when the eye has looked for a time on one bright light, it is inclined to clothe any smaller light near it, with the opposite or complementary colour, for the sake of relief Abstractedly, the explanation is plausible, but it will not endure the test of facts. In the first place, the law, if * There is no doubt that, in the course of long periods of time, stars change their colours. Sirius was celebrated by the ancients as a red star, now it is brilliantly white; and other changes have occurred of a like nature. It were more than vain to speculate re- garding the causes of these variations. They are indicative of a set of laws whose nature is yet wholly unknown. f May this distribution not be used as another argument in behalf of the physical connection of the stars? Does it not darkly intimate a common origin? See part third of our work. * 60 COLOR OF DOUBLE STARS. true, ought to be universal; whereas we find many sys- tems similar in relative magnitudes to the contrasted one, in which both stars are yellow, or otherwise belong to the red end of the spectrum. Secondly, if the blue or violet color were the effect of contrast, it ought to disap- pear when the yellow star is hid from the eye. Now, Struve refers to the three stars composing 0° Cigni. The. largest is of the fourth magnitude, and intensely yellow, while the others of the fifth and sixth magnitudes, are blue; and though the first be hid, these two preserve their blue color. The double star 6 Cygni affords, in my opinion, a still mºre emphatic confirmation of the truth; indeed, I marvel; how an observer who has seen these stars blazing, one with its yellow, the other with its in- tensely blue light, could have encouraged the optical hy- pothesis for one-moment. The constituents of this star are considerably apart, and may be separated by an ordi- nary teleseope. By means of a thin slip of darkened brass or copper, hide the one star, and note the color of the other. If the yellow star be hid, its companion loses nothing of its peculiar splendor; and if you observe the blue star, the other radiates preciscly as before Whate- ver the origin then, of this mysterious power, on the part of such binary stars, to divide as it were the light; or however it may be connected with the process which brought the systems into being, no shadow of doubt of its reality remains. And think of the novelties, or the petuliarities, which the existence of double and party- colorcd suns must cause to the planets encircling them “It may be easier suggested in words,” says Sir John Herschel, “than conceived in imagination, what a vari- ety of illumination two stars—a red and a green, or a yellow and blue one—must afford a planet circulating around either; and what cheering contrasts and grateful vicissitudes, a red and a green day, for instance, alter- nating with a white one and with darkness, might arise from the presence or absence of one or other, or both, from the horizon " All the products of the material constitution of this earth, the character of its living fami- lies, perhaps the action of its magnetic and other influ- ences, are co-ordinated and adjusted to the regular suc- THE UNKNowN, 61 cession of night and day, or to the supply and nature of our solar light. No such families then, none bearing other than remote analogies to ours, can exist in planets, engirdling such double suns. They, too, are surely the abodes of beauty and harmony, but their features are hidden from man—perhaps for ever. And who, after all, would grieve, although there are some enclosed spots— quietudes, in Creation, which will be unexplored, unpe- netrated for ever. Who that has felt the soft healing of Evening, can regret that, even in the intellectual world, there are regions into which faintness and weariness may sometimes flee, and take shelter and repose, away from the scorch and glare of oppressive light ! Sweet and in- viting mysteries—among whose gentle shadows Hope and Fear, and all unnamed yearnings, tremblingly ad- vance, and find or fashion for themselves images of puri- ty, convictions of immortality, vistas of a long life to come, through which the soul may wander freer and greater than now, “having gained the privilege by virtue !” - (62) LE T T E R V . TRIPLE AND MORE INTRICATE COMBINATIONS-EXIS" T ENCE OF LARGE GROUPS–CO N JECTURES RESPECT- ING THE FORM AND DISTRIBUTION OF CI, USTERS, ENGour AGED by the signal success which has attend- ed our investigation of the binary arrangements, whose phenomena we have just unfolded, we advance cautiously, but without dread, to take cognizance of still higher schemes. The arguments which induced Herschel to pronounce on the connection and motion of the constitu- ents of the simpler systems, penetrate much farther, and intimate, as a general law, that every cluster or unusual aggregation of orbs must be systematic, and probably wnited by common motion. If it is unlikely that the principle of random scattering would produce numbers of close PAIRs, it is still more unlikely that TRIPLE or QUADRUPLE BoDIEs should originate in fortuitous optical positions; and the presence of a great law thus lays it on astronomers as a command that they watch these higher systems, take their measurements with every mi- nuteness, and transmit them to posterity. * The occurrence of triple stars or of approximato con- junctions of three, is much rarer than that of Pairs, but still we find numbers sufficient to excite a profound inte- rest. Struve has specified 11 sets of bright triple stars; that is, of conjunctions of three bodies, within the space of 32", and none of which is too small to be seen with an ordinary telescope (none being smaller than his 8th mag- nitude); and of these 11 the calculation of probabilities will not permit us to suppose that more than one system owes its character to mere optical proximity. Systems of three sums connected by the physical law of attraction, MOTIONS OBSERVED. 63 and revolving perhaps round their common centre of gravity, are thus at once brought upon the scene. In another list our astronomer records 57 more within the same distance of each other, but in which one attendant belongs to the class of smaller magnitudes-a list con- taining likewise, without doubt, many physical systems; and in a third series of 59 similar combinations, not con- fined, however, within the limits of 32" of distance, he exhausts our present knowledge of the subject. The re- sults of the future and laborious examination of these systems are already foreshadowed. The double star & Cancri, which performs its binary revolution in a retro. grade direction in 57 years, is accompanied by a small companion in which motion has been seen, and which, if as is unlikely, it continued to perform its whole path with its present velocity, would accomplish a grand orbitual motion in about 600 years. Nor is ; Cancri the only gombination whose phenomena have realized our most sanguine expectations. In the three stars of ; Librae, the two nearer have performed half a revolution in 54 years, intimating 102 as their probable period; and the third has in that time moved in the opposite direction, only about the twenty-fifth part of an entire circle. Mo- tion has been suspected also in the triple star ip Cassio- peiae, but confirmation is here wanting. We can, hows ever, as before, deduce from the common proper motion of several double stars and their companions, the neces- . sary systematic connection of various groups not yet ob- served to change. For instance Castor, and the small star near it, must be a triple system; whilst 36 Ophiuchi (a double star of short period) and 30 Scorpii on the one hand, and Mizar (also double) along with Alcor, on the other, constitute related schemes upon the grandest scale. Is it wonderſul, with these prospects in the distance, that multitudes of enthusiasts are crowding into the service of Astronomy, and peers and princes vying for honorable motice in the science, by acts of costly patromage? T’assing from triple to yet higher combinations, we find every thing to hope. Near the brilliant star a Lyrae, a good eye discerns a star of a somewhat irregular or elongated form, When viewed through a telescope, this 64 HIGH AND STRANGE Com BINATIONs. irregularity is explained, for the star separates in two s and 5 Lyrae, distant 219" from each other, which also, by the test of their common proper motion, we know are physically connected Now each of these two stars is itself double, constituting a scheme like this. B 3& k •º. A. —a quadruple scheme, in which A will revolve around B, C around D, and perhaps both double systems, nicely balanced and harmonized round some intervening point. If we revert to our supposed law of necessary planetary existence—if the orbits of dependent worlds are intertwined around these four luminaries, we must indeed have strange systems in space, and mechanisms of a complexity which compels our boasted powers of analytical calculation, to confess themselves in the very infancy of progress Among Struve's first list of eleven physical triple stars, we find 0' Orionis—a star which, fully examined, turns out quintuple, or composed of five constituents so closely placed, that this distinguished astronomer declares them, without scruple, to be all conjoined by the force of attrac- tion This star is the celebrated trapezium in the nebula of Orion, and it seems that motion has been observed in it. Until Struve obtained the Dorpat telescope, only four stars had been seen in this beautiful cluster; but he had hardly examined it when he discovered the fifth. He lost no time in communicating the discovery to Sir John ller- schel, who confirmed it with his twenty-feet reflector, stating besides, that, if the star had been previously visible, he could not have missed it on occasion of his sketching with great care that outline of the Nebula, to which I will soon have occasion to refer. It has been said that the little stranger has again disappeared, having gone, proba- bly, to a remote part of its orbit: the disappearance, how- ever, is still apocryphal. Does the lost Pleiad—the sor- rowing Merope—refer, after the fashion of that beautiful mythology, to a similar phenomenon, the retirement of a star formerly visible 2 The Pleiades must be connected and bound by mutual relations. In Harding's Atlas, we COMBINATIONS OF STARS, - 65 find in that constellation 1 star of the fourth magnitude, 6 stars of the fifth, 5 of the sixth, and 32 of the seventh— in all 44 stars within a circular space of the radius of one degree; and the probability of their merely optical connection is measured by the almost evanescent fraction I Hºgjiāº; These are but glimpses of what an analysis of such celestial collocations will yet reveal; but one's satisfaction in their contemplation is almost damped by reflection on the time and labor still necessary to explore them. . On referring to the field they open—to the little hitherto accomplished, compared with what remains to be done—to the deep mystery still hanging over almost all the skies—there is apt to supervene a despondency, a hopelessness that the handwriting which is on them, will ever be interpreted. But we take encouragement from the aspects of the times. Astronomy is not now in that stage of its history in which only a few men in a century would consent to wear out a long and healthful age in examin- ing the Heavens. Observers of the first capacity and of becoming ardor, are yearly multiplying; while adequate instruments, through the advance of Art, grow more ac- cessible. Doubtless, with all advantages, we, of this time, may do little more than roughly chart the boundary lines, and it may be, fix down the prominent points of the landscape —the filling up and mapping of the details constitute the harvest of the future . But how soon may that future come ! The wheels of time are revolving rapidly—truth mingling with truth, as light gathered into a focus. Alike within and around us, events succeed without the usual interval, nor is astronomy unaffected by the general acceleration. The knowledge of what the Heavens are boding may not be long deferred; if we, in present times, industriously act our part, much, still unin- telligible, will become plaim to the generation whose buds at this moment are the spring tidings of the world—the generation now pressing on us, and to which we must yield the stage. - But our reasonings from probability extend much far- ther than to minor small collocations and clusters within 66 SPECULATION S-HOPES OF THE FUTURE. our firmament, and reveal certain grand, though still sub- ordinate, modes of activity to which the firmament itself must be subject. On looking at our vast bed of stars, we find marks in many parts of it of striking peculiarity, and indications of system which it is impossible to overlook. It seems to consist of two great portions, in so far, isolated, viz. the Ring or Milky Way and central mass (See Fig. I. Plate III.); in each of which some subordinate system must reside. We know little of the constitution of the central mass, but observation establishes certain clear truths regarding the composition of the Ring. It is by no means an uniform zone, but rather a succession of bright spots, generally separated from each other by a comparatively dark line or space, manifesting a succession of clusters easily detected by the naked eye. These groups are for the most part of a spherical form, and are in many cases almost isolated. Nor is the peculiarity confined to the Northern Hemisphere. Plates XI. and XII. are eye sketches of part of this zone by Mr. Dunlop, showing its aspects in the southern hemisphere; which you will observe correspond precisely with my description of its northern regions. It is not improbable that the Magellanic clouds in the south, differ in nothing from these groups, save that they stand alone; while the others form a successive bed or stratum through the Heavens. In both, unquestionably, there is system, and ongoings of motion and change under control of that same law which stirs the double stars into action. “How much,” says Sir John Herschel, in the enthusiastic con- fidence that even the immensity of such motions is not beyond reach of our faculties, “how much is escaping us! How unworthy is it in those who call themselves philosophers, to let these great phenomena of nature— these slow but majestic manifestations of the power and glory of God—glide by unnoticed, and drop out of me- mory beyond reach of recovery, because we will not take the pains to note them in their unobtrusive and furtive passage, because we see them in their every-day dress, and mark no sudden change, and conclude that all is dead, because we will not look for signs of life; and that all is uninteresting because we are not impressed and PL., XII. THE MILKY WAY. 67 dazzled.” “To say indeed,” he adds, “that every indi- vidual star in the Milky Way, to the amount of eight or ten millions, is to have its place determined, and its mo- tion watched, would be extravagant; but at least let sam- ples be taken—at least let monographs of parts be made with powerful telescopes and refined instruments—that we may know what is going on in that abyss of stars, where at present imagination wanders without a guide!” If the central mass be at all uniform, perhaps its whole suns will be united by one direct and primary sympathy; but it also may be made up of mighty subordinate groups. Proofs of motion among its stars, illustrative of the one or the other phenomenon, are not now strange or unfre- quent. I have mentioned in several parts of our discus- sions that great numbers of the stars enjoy proper motion —motions whose rates are fixed in many cases, and which affect bodies lying on all sides of the sun. Whether this is the activity of a subordinate group, or of the whole central mass, it is now clear that our sun partakes of it, and that he is sweeping along with his whole planets rap- idly through space towards a space in the constellation Hercules. This important motion, first announced by Sir William Herschel, was afterwards thrown into dis-, credit by the criticisms of some of our most acute modern astronomers; but we have the testimony of Struve that it is triumphantly re-established in a prize-dissertation by M. Argelander, which has not yet reached this country. The more we know of the heavens, the more are we con- strained to wonder at the activity and acuteness of our illustrious Astronomer. Bold as he was, and fond of ge- neralizing, there is scarcely one single conjecture upheld by the authority of his name, which subsequent discovery has invalidated, and the most daring of all have been amply confirmed. Surely “the freshest stamp of Divi- nity was upon him 1'-Of the periods of such motions as may sustain the groups I have now spoken of not even imagination can form an idea; the periods of the grandest double stars willsink beside them into utter insignificance, and seem like to the evanescent years of earth! But in this exquisitely related Universe, where the great and the 68 GRAVITY IN CLUSTERS OF STARs. small are interlaced and form one whole, even those boundless and immeasurable motions may not pass, with- out affecting and assisting through their allotted destinies, the small planets encircling our sun. The recent conjec- ture of a continental analyst is not to be summarily reject- ed or overlooked in a philosophical induction—that a de- gree of those changes of temperature which the earth has undergone since life appeared in it, and because of which our northern climes were one day capable of harboring the palms and gigantic ferns of the tropics—may have supervened in consequence of our gradual translation into ehiller regions of space. (See Note E.) * . We approach the land of clouds and doubt—the solid ground of fact and observation is rapidly retiring from below us. Of the relations of these subordinate groups, or of the binding or compacting principle of our singular firmament—considering it as a whole,_-I can inform you nothing. The more capricious class of external clusters equally mocks our imaginings, although the application of the principle of probabilities fully assures us that these masses are not grouped together by chance or at random, but that through every such union of stars, law and sys- tem must prevail, as clearly as in binary or termary ag- gregations. The only light we find among these spaces is a welcome gleam of evidence that Nature, there also, is uniform, since the simpler firmaments manifest by their shapes the prevalence of an internal attractive power— like that whose effective presence bestows consistency on our own subordinate clusters. Notwithstanding the ap- parent caprice of many of the firmaments, the round or globular structure is the general or favorite one, as you may judge from the representations in Plates I., W., W.I.; and in most of these round clusters, there is also a strong- ly marked increase of light towards the centre, much more than would arise from the circumstance of our look- ing through the deepest part of the group, and thereb seeing at once the greatest number of its stars. This latter phenomenon decidedly indicates compression in greater or less degree, nor is it confined to masses having the perfectly spherical figure. “There are besides,” says Sir William Herschel, “additional circumstances in THE EFFECT OF OBSERVATIONS. 69 the appearance of extended clusters and nebulae, which very much favor the idea of a power lodged in the bright est part. Although the forms of these are not globular, it is plainly to be seen that there is a tendency towards sphericity, by the swell of the dimensions the nearer we draw towards the most luminous place; denoting, as it were, a course, or tide of stars, setting towards a centre. And, if allegorical expressions may be allowed, it would seem as if the stars, thus flocking towards the seat of power, were stemmed by the crowd of those already as- sembled, and that, while some of them are successful in forcing their predecessors sideways, out of their places, others are themselves obliged to take up lateral situations, while all of them seem eagerly to strive for a place in the central swelling and generating spherical figure.” Arrived at this giddy height, we stop our train of thought—not unwillingly, for imagination is growing weak. The time may come, when we can pursue these contemplations with more steadfastness—when accurate Science shall have gone before us with her torch, and re- moved all cause of bewilderment. Anticipating such achievements, one almost participates in the elevation of the men who will realize them; and this mood would best lead us to estimate the worth of those who have gone before, and conquered what we now enjoy. It is indeed attractive to revert to the period when the forty-feet teles- cope first interrogated these profound heavens ! The enthusiastic observer in the act of discovery, rises before the imagination, amid the peace of midnight and the beau- teous twinkling of stars; as also that other feature which characterised and farther elevated the scene. The As- tronomer, during these engrossing nights, was constantly assisted in his labors by a devoted maiden Sister, who braved with him the inclemency of the weather—who heroically shared his privations that she might partici- pate in his delights—whose pen, we are told, committed to paper his notes of observations as they issued from his lips; “she it was,” says the best of authorities, “who having passed the nights near the telescope, took the rough manuscripts to her cottage at the dawn of day, and produced a fair copy of the night's work on the ensuing 70 * MISS CAROLINE HERSCHEL. morning; she it was who planned the labour of each succeeding might, who reduced every observation, made every calculation, and kept every thing in systematic or- der;” she it was—MIss CAROL: NE HERscHEL–who helped our astronomer to gather an imperishable name. This venerable lady has in one respect been more fortu- mate than her brother, she has lived to reap the full har- vest of their joint glory. Some years ago the gold medal of our Astronomical Society was transmitted her to her native Hanover, whither she removed after Sir William's death; and the same Learned Society has recently in- scribed her name upon its roll: but she has been re- warded by yet more—by what she will value beyond all earthly pleasures—she has lived to see her favorite ne- phew, him who grew up under her eye unto an astrono- mer, gather around him the highest hopes of scientific Europe, and prove himself fully equal to tread in the foot- steps of his Father, - - P A R T III. THE ORIGIN AND PROBABLE DESTINY OF THE PRE- SENT FORM OF THE MATERIAL CREATION. LE TT E R V I. *~ THE NIEBULAC. ALL that the telescope, aided by a bold and accurate science, has unfolded concerning the activity, forms, and condition of the Stellar Universe, is now before us. Pon- dering on its strange outline, we ask, hesitatingly, whether these arrangements are fixed, whether, what we behold, is the picture of all time, or whether visible phenomena have not a deeper significancy, and are not results of a pre-existing state, or germs of something future ? These questions warn me, that again we break new ground, and enter on speculations, perhaps the most adventurous which have yet engaged the reason of Man. Astronomy has recently been obliged to recognise a Matter—or rather a modification of Matter, wholly dis- tinct from stars—a thin and filmy substance diffused through the stellar intervals, and spreading over regions so immense, that its magnitude or the space that it fills, is absolutely inconceivable. It unquestionably becomes us not to admit an element so remarkable—and which, if real, must perform important functions, and materially affect our general views of things—until its claims have undergºne the severest scrutiny; and, as I am desirous to convey to you full power of judging for yourself, I will here minutely follow the process of thought, by which Sir William Herschel—only, however, at a comparatively late period in the course of his researches—was, slowly and almost reluctantly, led to the conviction of its reality. 6* - 72 II ERSCHEL's opSERVATIONs. In his earlier inquiries, Herschel was inclined to con- sider all the fantly illuminated spots in the heavens, as clusters so remote, that only their general illumination, and no individual object, could be seen; and the inference, so far from being constrained, seemed to result from his whole previous experience. On viewing the heavens, for instance, with a seven-feet reflector, while many distinct clusters were revealed to him wholly invisible by the naked eye, a great number of new illuminated spots were also visible. Now, on applying the ten-feet telescope, a proportion of these last were at once resolved into stars; others, formerly of a milky hue, put on the resolvable as- pect; that is, they seemed like a distant handful of glit- tering dust; and although many retained their former irresolvable appearance, what more matural than to refer their continued intractability to their still greater distance? “When I pursued these researches,” says our Astrono- mer, “I was in the situation of a natural philosopher, who follows the various species of animals and insects, from the height of their perfection down to the lowest ebb of life; when, arriving at the vegetable kingdom, he can scarcely point out the precise boundary where the animal ceases and the plant begins, and he may even go so far as to suspect them not to be essentially different. But, recol- lecting himself, he compares, for instance, one of the hu- man species with a tree, and all doubt upon the subject vanishes before him. In the same manner we pass, by gentle steps, from a coarse cluster down through others more remote, and therefore of a finer texture, without any hesitation, till we find ourselves brought to an object such as the NEBULA in OR1ON, when we are still inclined to remain in our once adopted idea of stars exceedingly re- mote, and inconceivably crowded, as being the occasion of that remarkable occurrence, It seems, therefore, to require a more dissimilar object to bring us right, again. A glance like that of the Naturalist who casts his eye from the perfect vegetable to the perfect animal, is want- ing to remove the veil from the mind of Astronomers.” The object which broke in upon Herschel's previous continuity of inference was a nebulous star—a perfect star with a halo or dim atmosphere around it, such an object NEBULAE IN ORION. 73 as is represented in Fig. 1, Plate XX. I tramscribe the record of the observation, and his subsequent remarks. After noting the elements which fix the star's place, he says, “A most singular phenomenon A star of about the eighth magnitude with a faint luminous atmosphere of a circular form, and about 3' in diameter. The star is perfectly in the centre, and the atmosphere so diluted, faint and equal throughout, that there can be no surmise . of its consisting of stars.” Herschel arrived at the latter positive conclusion as follows. “In the first place,” says he, “if the nebulosity consists of stars appearing nebu- lous because of their distance, which causes them to run into each other, what must be the size of the central body which, at so enormous a distance, yet so far outshines all the rest ? In the next place, if the central star be no big- ger than common, how very small and compressed must be the other luminous points which send us only so faint a light? In the former case, the central body would far exceed what we call a star; and in the latter, the shining matter about the centre would be too small to come under that designation. Either, then, we have a central body hich is not a star, or a star involved in a shining fluid of a nature wholly unknown to us.” The latter alterna- tive may, at first sight, appear the strangest and the most remote; yet it is the one to which the balance of proba- bility manifestly inclines. And our judgment rests upon this, the nebulous fluid, supposing it to exist, could not become known under any other aspect or modification ; while if stars of enormous comparative dimensions, were scattered through space, the likelihood is, that some one such body would be sufficiently near us to permit of our recognising it under less ambiguous characters. $ Many other appearances, admitting of no plausible solution on the supposition that all those dim lights are sent from remote and accumulated stars—sustain the in- ferences just deduced, and thus greatly augment their pro- bability. The wonderful Nebula in Orion, is in this respect a most instructive phenomenon. On directing the unaided eye to the middle part of the sword in that beau- tiful constellation, the spectator fancies, on the first im- pulse, that he sees a small star; but closer observation 74 NEBU L WE IN ORION. shows him that it is something indefinite and hazy, having mone of the distinctness of the minute stars. When he looks at the spot through a small telescope, these suspi- cions are confirmed; and as the power of the telescope is increased, the more diffuse and strange the object becomes. Its form, as revealed by a twenty-feet reflector, is shown in plate XIII. ; but there is reason to believe that its low situation in our latitudes, conceals many remarkable radiating branches which are seen in the southern hemi- sphere. Now, observe two facts;–the Nebula is visible to the naked eye, and distinctly visible through glasses of small powers; and the whole light and efficacy of the forty-feet telescope could not resolve it into distinct stars. But, to be irresolvable by the largest telescope, the stars in the Nebula—supposing it a cluster—must be placed at a distance from us, which we cannot express in language; and, to enable them to send us even a milky light through so vast an interval, they would require a most improbable compression,-improbable, because unknown in degree, even in any explored portion of the universe. The hy- pothesis of a filmy or Nebulous fluid shining of itself, is thus again forced upon us, precisely as in the case of the Nebulous stars; and our general argument is here far ther and very strikingly supported by the ascertained peculiarities of the mass. When telescopes are not suffi- ciently powerful to resolve a cluster, it still commonly takes on a succession of appearances, which distinctly in- dicate to the experienced observer its resolvabilty, or stel- lar constitution. In the Nebula in Orion, however, no such change appears. It grows brighter in one sense, the larger the telescope, but only to become more myste- rious. As we then see it, the illumination is extremely unequal and irregular. I know not,” says Sir John Herschel, “how to describe it better, than by comparing it to a curdling liquid, or a surface strewed over with flocks of wool, or to the breaking up of a makerel sky, when the clouds of which it consists begin to assume a cirrous appearance. It is not very unlike the mottling of the sun's disc, only—if I may so express myself—the grain is much coarser, and the intervals darker; and the flocculi, instead of being generally round, are drawn into |’ U.N. III . IT'S WOLUME-REFLECTIONS UPON IT. 75 little wisps. They present, however, no appearance of being composed of stars, and their aspect is altogether dif- ferent from that of resolvable Nebulae. In the latter we fancy by glimpses that we see stars, or that, could we strain our sight a little more, we would see them. But the former suggests no idea of stars, but rather of some- thing quite distinct from them.” This great Nebula seems to occupy in depth the vast interval between stars of the second or third, and others of the seventh or eighth mag- nitudes, and its superficial extent probably corresponds; its absolute size is thus utterly inconceivable; for the space filled by a Nebula of only 10' in diameter, at the distance of a star of the eighth magnitude, would exceed the vast dimensions of our sun, at least 2,208,600,- 000,000,000,000 times | Although, to the interruption of our course of logical proof. I cannot refrain from adverting to some of the en- grossing contemplations which never fail to occupy me when I gaze upon this remarkable substance. What is the intention of such a mass 7 Is it to abide for ever in that chaotic condition—void, formless, and diffuse in the midst of order and organization,--or is it the germ of more exalted Being—the rudiments of something only yet being arranged? Then, too—although these questions were answered—what is, its present state? It is not enough to tell us that for such and such ultimate purposes a certain object is destined;—we would know farther the peculiarities and adaptations of its present or actual con- stitution ? No part of creation exists merely as a means; every thing is besides an end to itself: and within that looming mass, whatever may be its final destiny, there are doubtless wide and systematic relationships;-each particle of its matter will be arranged and adjusted to its neighbor; nay, who can tell—who that has looked on those monuments of bygone worlds, the fossil relics which mark the early progress of our own planet—but, this amorphous substance may bear within it, laid up in its dark bosom the germs, the producing powers of that LIFE, which in coming ages will bud and blossom, and efflor- esce, into manifold and growing forms, until it becomes 76 oTHER NEBULE AND CoMETs. fit harborage and mourishment to every varying degree of intelligence, and every shade of moral sensibiliiy and greatness | - Probable evidence of the foregoing mature might now be almost indefinitely accumulated. For instance, the magnificent appearance in the girdle of Andromeda af. fords similar conclusions. This Nebula, represented by Fig. 1, Plate XIV., is distinctly visible to the naked eye, seeming like a greasy spot on the dark blue of the firma- ment, or a light shining through a horn; but, as with the Nebula in Orion, no telescopic power has yet sufficed to give it the resolvable aspect. Farther pursuit of such considerations, however, is unnecessary, inasmuch as we are in a condition to produce, what—taken in supplement —amounts to positive and direct proof at once of the re- ality and extensive diffusion of the Nebulous substance, I request your attention to the phenomenon of ComETs.- There is much connected with the comets of which we yet know nothing; but two general and essentially char- acteristic facts are established, and these suffice for my immediate purpose. In the first place the phenomenon demonstrates not the possibility merely, but the actual presence in Nature of a nebulous modification of matter. The comets are nothing but nebulosities, small portions of a substance precisely similar in physical constitution to that which our hypothesis assumes. Even their nuclei dissolve into a fog under the inspection of the telescope. Fig. 2, Plate XIV., is a sketch by Sir John Herschel, of the second comet of 1825, and through the heart of an- other, the same observer once descried a cluster of stars of the sixteenth magnitude. Secondly: These small ne- bulosities are not connected with the structure of our solar system; from which we infer that they are connected with some system in the spaces eacternal to our limited sphere. There is no essential tie between us and these comets; the variety of directions from which they come, altogether distinguishes them from the bodies which roll around the sum with singular and systematic regularity; they are chance visitants, most of them perhaps never approaching us but once; for, unless in a few instances, Pl, XIV". MEANING OF COMETS. 77 there is little reason to believe that their eccentric paths are continuous, or that they re-enter into themselves, and form a definite and bounded curve. But shall we there- fore go into the usual inference, that the comets are mere anomalies—freaks of nature ? Because they have no connection with the order of our planetary worlds, is it necessary that they should have no meaning—no place in the universe? Look around you ! What is there, what existing creature, which has not such a place 7 Of the fine web of Being, fitness and relation are the warp and woof. Apparent anomalies are mere finger- posts, pointing where things lie of which we continue ignorant; and when such intimation is received with phi- losophic meekness, it invariably guides to unexpected discovery. These hazy bodies, now and then reaching our system, and leaving it without ever producing an appreciable effect, are not spectral and isolated monstra ! As all things have a home in mature, they, too, doubtless hold relations with some grand external scheme of matter in a state of similar modification: and since, when influ- enced by the sun's attraction, they approach us from all quarters of the heavens, the nebulosities in which they have their Root, must lie around us on EveRY SIDE, and be profusely scattered among the intervals of the stars. What an error to fancy these Comets anomalies? They demonstate that, which, as we have seen, is re- quired to make a large and varied series of phenomena explicable. They are, in fact, absolutely indispensable; for without them the conjectural disclosures of the tele- scope would scarcely be established. And, in accom- plishing this service, they have also vindicated their own position; so that we have at once two of our best intima- tions—that knowledge is advancing, -remote phenome- ma appear in the closest relationship, , and objects and occurrences, formerly deemed insignificant, assume a place as constituents of the compact fabric of the Uni- VerSe. - We touch on the most obsure problem of Astronomy. As every atom in existence has its object, this nebulous matter, found in such abundance, must have a prominence 78 .* what ARE THE NEBULE 7 in purport answering to its prominence in magnitude. But when we ask, What are the Nebula 2 we feel that we are venturing into that dim twilight which always surrounds the sphere of positive knowledge. If we would understand them, however, or know whether they are intelligible, we must examine if they can be arranged under characteristic peculiarities of structure, indicative of the operation of LAw; and it was the endeavor so to arrange them which led the Astronomer, whose torch has hitherto guided us, to conjectures promising, now more confidently than ever, to throw unwonted light upon the course of material transitions. I have, by means of diagrams, illustrated this part of our subject so fully, that I am encouraged to hope my reader will easily follow the arguments we are about to entertain } In its first or rudest state, the Nebulous matter is char- acterised by a great diffusion. The Nebula in Orion is an example of this, and Plate XV. represents a few other instances in which the milky light is spread over a large space so equably, that scarcely any peculiarity of consti- tution or arrangement can be perceived. The perfectly chaotic modification here illustrated, is perhaps the near- est to the original state of this matter of any thing now remaining in the firmament; but the reason of its being found in separate patches, varying so much in form, ma- mifestly appertains to remote inquiries, and an inaccessi- ble period in the History of Things, Parting from these perfectly diffused and amorphous Nebulosities, STRUCTURE, as governed by LAw, begins to appear. Even its first visible indications are very empha- tic. The winding Nebulosity in Plate XVI. for instance, exhibits a congregating or condensing of the filmy matter in two distinct places, which look like bright nuclei, sur- rounded by a comparatively dark ring, precisely as if they had been formed by an actual condensation of the #. matter under control of the law of universal at- traction. This is no anomalous appearance, for, in every case, the seeming commencements of structure are of the same kind. Nothing is any where met with like a dis- persion, or indication of a dispersive power; which pro- bably would have been seen, had any power but an I'l XVII. - º . º APPEARANCE OF STRUCTURE IN NEBULAE 79 aggregating or condensing one been influential over the condition of nebulosities. This aggregating power, in- deed, without the interference of any other, appears to lead to the entire breaking up of amorphous masses. The number of nuclei which are found in distinct nebulae is variable; but there is never a departure from the charac- ter due to their supposed origination in a condensing prin- ciple. We have always a regular gradation in their intensities. The point of light grows brighter, while the vacancies or dark circles around the pcints are marked with more and more distinctness, until we reach a cluster of small round nebulae perfectly detached from each other. The first figure in Plate XVII. represents an early stage of the phenomenon described; and the others in the same plate carry on the process of apparent separation in regard to two nuclei, until the masses are altogether distinct. The progress may be traced still farther. In their ulti- mate condition—that condition I mean in which they seem to merge into stars—we find them distinguished from a double star or cluster, only in this, that they rest on a bed of very faint light. Of course, when I speak of progress, I would be understood to signify the progress through a series of related contemporaneous objects in different and graduated states—not that progress which has never been observed—the passing, viz. of one nebula from an inferior into a higher condition. But is the con- clusion rash, that this latter progress is possible 2 Is it not darkly but impressively intimated by the unbroken integrity of the series? What principle of philosophy hinders the supposition, that each of these varying bodies holds with those on both sides of it, also the relations of progenitor and descendant, that the unbroken contempo- raneous series is also a picture of youth ripening and manhood—in short, that the principle of attraction has actually brought such distinct round nebulae as are seen clustering together, and also collections of stars imbedded near each other on a whitish light, from the bosom of masses like those looming elsewhere—still all indefinite- ly—among the recesses of our firmament 7 The hypothesis I have started is so strange, and brings up notions so unlike our common thoughts of the stellar 80 FORM OF NEBULAE. universe, that it cannot and ought not to be received with- out an almost superfluity of evidence. We turn, accord- ingly, to single and definite Nebulae, which are possessed of marked structure, in search of the light which they may throw upon it. And we get nothing here but confir- mation. Their shapes, and the distribution of light in the separate bodies, so entirely accord with the hypothesis of condensation, that we have hardly room for evasion or escape. Single Nebulae characterised by structure vary consi- derably in form, the usual varieties are shown in Plate XVHI. Some are of an oblong shape, like that in An- dromeda, with marked condensation towards the centre. We know not how these flat zones originated, but even in them, structure when manifested, always indicates con- densation around the apparent centre of the mass. The great proportion of distinct nebulae, however, are round, or nearly so. In Sir John Herschel's recent catalogue, the immense proportion are marked as round. Now we are bound to infer, that these round masses are spheres ; for there is no likelihood, that if they were cones or cy- lynders, they would all so lie in regard to our line of sight as invariably to present their circular sections. But the sphere is the shape naturally assumed by masses whose particles mutually attract each other; and, on the principle that the globular shape of the rain-drop is ac- cepted as a common illustration of the all-prevalence of gravity, and the sphericity of the planets held to confirm the same important law, this, tendency in the nebulae to the round form must be received as a weighty and import- ant argument. But it is the mode of the distribution of their LIGHT, which most confirms and settles these views. On the very first glance, this seems a pheno- menon connected with central influence; for not only is the illumination uniformly greatest at the centre, but if in any nebula a circle of any radius be described around the centre, the illumination will be ſound of the same intensity at every point of its circumferenee. By far the most remarkable and important fact, however, is that wonderful gradation in the intensity of the central light. Plate XIX. speaks to the eye, ...'is more valua- CENTRAL LIGHT-REFLECTIONS. 8 | ble than pages of description. Each figure in that plate is the representative not of an individual, but of an exten- sive class; and surely a series so well marked—so strik- ing in its aspects—must indicate the presence and influ- ence of a great law 7 From absolute vagueness, to dis- tinct structure, and then on to the formation of a defined cen- tral nucleus, the nebula seems growing under our eye The illustration of Laplace, reproduced by Mr. Airy, here forcibly occurs to me: “We look among these ob- jects as among the trees of a forest; their change in the duration of a glance is undiscoverable; yet we perceive that there are plants in all different stages; we see that these stages are probably related to each other in the order of time, and we are irresistibly led to the conclusion, that the vegetable world in the one case, and the sidereal world in the other, exhibit at one instant a succession of changes requiring time, which the life of man or the du- ration of a solar system may not be sufficient to trace out in individual instances.” And the progression advances until it is complete. We have objects each more perfect than the last, like those Figures in Plate XX. ; and in the end a st AR is found thoroughly organised with a mere bur around it ! Let us collect together and review for a moment the whole facts of this curious speculation. First: We dis- cover a most striking series of objects partaking of the same nebulous constitution, and connected in an unbroken external chain or gradation, each object or link of which exhibits the nebulous chaos in a condition of greater re- gularity and higher consolidation than the preceding one ; and the gradation only closes on reaching an organized star. Secondly : We are acquainted with an influence or process operating on every side of us, an influence the most general in Nature, capable of effecting the con- version of a Nebula of one series into a more advanced one of the next; or, to use more accurate language, the actual occurrence of such conversions would be far from unusual or strange, but rather in exact agreement with the course of that most extensive class of material events, whose laws we have hitherto recognised. It is a dis- 82 PHENOMEN A OF CHANGE. tinguishing mark of this hypothesis, that we institute no new power, nor speculate on mere possibilitiet; that Nature is uniform—that GRAVITY which controls the planetary, and, in so far as we know, all celestial spheres, acts also within these masses, is our boldest supposition. And, besides, there are positive indications that it does act there. The comets are under its influence, for they are attracted by our sun; their matter, therefore, is the same as planetary matter—obedient to gravity. Instances, too, are not wanting in which the original distribution of external nebulosities appears affected, or altered by the attraction of neighboring stars. The upper and lower figures in plate XXI. shew portions of it being drawn towards a star—as if feeding it—or stretched between two. The middle object in the same plate is very in- structive. It is a diffused nebulosity near a tº cluster of small stars, and its brightness follows their line; while in the spaces where no stars are, there is almost no nebulous matter, as if it had been nearly drawn away by attraction, and accumulated in those bright ridges, or absorbed. I anticipate the objection of the difficult believer, “Shew us,” he will say, “shew us a change, shew us the actual progression of one nebula from an inferior to a more organized condition. We grant the unbroken completeness of your series; we grant the law which could advance its individual constituents; but actual change alone is proof” Let no man, however, be de- ceived, or mistake the nature of the problem which is engaging us. The demand is infinitely more unreason- able, than if the inquirer into the motions of the double stars were to insist upon an actual inspection of the be- ginning and close of the vast year of Mizar and Alcor. If that nebular hypothesis be true, all the forces developed upon the thin surface of our planet, and which have given rise to geological transitions, stretching through periods in which the existence of the human race is an invissible speck, will have resulted during a stage of condensation in a secondary nebula, which no instrument from any fixed star could possibly detect. How, them, delude or disappoint ourselves by straining the eye aſter periods CHANGE INDEPENDENT OF TIME. 83 so enormous! There is a creature named the Epheme- ron, whose life is confined to the veriest point of time;-- in one short hour it dances out its existence in the sun- beam. That creature is in presence of all the pheno- mena of vegetable growth; it may see trees—it may see flowers, but how could it or its generations actually ob- serve their progressive development? In relation to the nebulae, Man is only an Ephemeron. Fifty lives suc- ceeding each other, and of a length to which individuals often attain, would reach backwards beyond the recorded commencements of his race; and in the mutability of things, fifty more may constitute a line longer than his allotted epoch. And, no more than one hundred of those creatures, which are born, breathe, and die, could learn of the progress upwards of the majestic pine,—will Man ever learn of the changes of the Nebulae The ideas I have now presented to you—august and strange though they are—should not appear in contra- distinction to what every moment is passing around us. Supposing these phenomena did unfold the long growth of worlds, where is the intrinsic difference between that growth and the progress of the humblest leaf, from its seed to its intricate and most beautiful organization? The thought that one grand and single law of attraction ope- rating upon diffused matter may have produced all those stars which gild the heavens, and, in fact, that the spang- ling material universe is, as we see it, nothing other than one phase of a mighty progress, is indeed surprising; but I appeal to you again in what essential would it be differ- ent from the growth of the evanescent plant? There, too, rude matter puts on new forms, in outward shape most beauteous, and in mechanism most admirable: and there CANNOT be a more astonishing process or a mightier power even in the growth of a world ! The thing which bewilders us is not any intrinsic difficulty, or disparity, but a consideration springing from our own fleeting condition. We are not rendered incredulous by the natu, e, but overwhelmed by the magnitude of the works; our minds will not stretch out to embrace the periods of this stupendous change. Put Time, as we con- 74 - 84 SHORTNESS OF HUMAN LIFE. ceive it, has nothing to do with the question—we are speaking of the energies of that Almighty Mind, with regard to whose infinite capacity a day is as a thousand years, and the lifetime of the entire Human Race but as the moment which dies with the tick of the clock that marks it—which is heard and passes, (85) L.E. T. T E R W II. THE NEB O LAR HYPOTHESIS. LET us note the exact amount of evidence constituted by the speculations of the foregoing letter, on behalf of the daring Hypothesis that all existing stellar bodies sprung by virtue of the law of attraction, from the bosom of a chaos of which stray specimens are still found in the Heavens. In so far as this Hypothesis undertakes to ExPEAIN THE NEBULE, I do not conceive that much of accessible knowledge is now wanting to confirm it; for, the agreement of the forms of the nebular substance with the natural results of the persevering action of gravity, seems almost demonstrated. But it must not be forgotten that there is another correlative and very extensive in- quiry which this truth has not touched; This Hypothe- sis must also ExPLAIN THE STARs. If it is the true Cos- mogony, and we have at length approached a right theory of the Formation of Things, we should indeed obtain from it a satisfactory idea of the meaning of that curious pro- gression of structure, which so strikingly characterises the Nebulous masses; but it is no less imperative that it exhibit with proper distinctness, how the mass of stars around us, along with their peculiar features and ar- rangements, might have been evolved in obedience to known mechanical laws, by the condensation of Nebulae. To the inquiry thus suggested, I invite you rejoicingly; at every step in our pursuit of it, we shall gain new views of the unity of Things, indications of remote and unex- pected relationships, and proofs the most illustrious afford- ed by Science, of the compactness of that Domain whose forms occupy SPACE, and the annals of whose changes constitute TIME. 86 THE SUN A NEBU LOUS STAR. I. There is no small difficulty in reconciling the im- agination to the idea that an orb like our SUN–on which, as in our former survey, we naturally first cast our eyes —could have originated in a vague nebulous mass. Ob- servation shows, however, that the magnitude of our lu- minary is no obstacle to the Hypothesis, for the statement in page 74 proves that a Nebula like that in Orion, con- tains matter or substance sufficient for the generation of a solid globe perhaps some millions of times as large. Nei- ther can the difference between the solidity of the Sun and the gaseous condition of the Nebula, constitute ground for rational hesitation, inasmuch as in the laboratory of the chemist, matter easily passes through all conditions, the solid, liquid, and gaseous, as if in a sort of phantasmago- ria, and his highest discoveries even now, are pointing to the conclusion that the bodies which make up the solid portion of our Earth may, simply by the dissolution of existing combinations, be ultimately resolved into a per- manently gaseous form." But it should wholly reconcile you to this preliminary conception, if, partly by what seems the true interpretation of a phenomenon long no- ticed, and partly by aid of one of the most promising dis- coveries of modern times, I show that the SUN is not yet pure, that he has not yet quite escaped the original me- bulous character I am attributing to him, and that, not- withstanding his effulgence, he is still rather in the con, dition of a nebulous body—something like Fig. 1. Plate XX., where consolidation, although very far advanced, is not complete. The first appearance referred to is the ZoDIACAL LIGHT. This remarkable phenomenon consists in a long train of ſaint light of a conical form, left by the sun after setting, and projected on the sky; . It is easily seen in tropical countries, but in ours it is visible only when in the most favorable position, and may be looked for on clear evenings in March or April. It has an appearance like that in the subjoined wood-cut, where S is the sun, * See note C. at the close of the volume. zodiacAL LIGHT. 87 2. FI HO the horizon, and ZL the faint light. Now, the axis on which the sun rotates is, as the Figure indicates, at right angles to the greatest length or aa is of the light; from which simple fact, we venture to trace a connexion between that light and the axis or equator of the sun. Al- though we see only the upper part of it, that atmosphere is in all probability extended also on the sun's other side, as in the dotted part of the line; forming a regular and still uncondensed relic of some oblong nebula, in which our luminary probably originated. Of this at least we are certain—the Zodiacal Light is a phenomenon pre- cisely similar in kind to the nebulous atmospheres of the distant stars; and, these atmospheres have already been connected by a long and unbroken progression with their parent amorphous masses. In relation to its extent, in- deed, it is utterly trifling when compared with the small- est of the stellar nebulae; for its diameter is less by mil- lions of times than the average of these curious bodies, and if we looked from the nearest of the fixed stars we could not recognise it or guess its existence with the aid of Herschel's largest telescope; but this fact, so far from being barron or forbidding, is itself a ground of important and cheering reference. Previous even to the discovery of such a circumstance, no one could have asserted con- fidently that the nebulous atmospheres of the stars ter- minated actually at the point of magnitude below which 88 PHENOMENA of zodiacAL LIGHT. we cannot see them, or at the varying limits of their visi bility to us: but we are now furnished with substantive reason to believe that the phenomenon of the illuminated bur does extend much farther; that vast numbers, if not the whole, of the bright and apparently pure constituents of our firmament, may still have Zodiacal Lights; and that the nebulous phenomenon, although to our imperfect vision now characterising but comparatively few objects, may, notwithstanding the long lapse of hither time, con- tinue to possess a generality of which all that we see is only the faintest indication. The other and new phenomenon—one no less remarka- ble in the mode of its discovery, than because of its in- trinsic value—is equally confirmatory of the nebulous at- tributes of the sum. The nebulous stars, as seen by our telescopes, have vory commonly a well marked increase of light toward the centre; or, what is the same thing, a gradual diminution, or shading off, towards their edges. Now, this Zodiacal Light is probably only the brighter part of the solar nebulosity, which may extend much far- ther. In this further extension it may not give out suffi- cient light to be perceptible; and the fact is, if it includes the Earth, we could not see it, although it emitted a very considerable quantity of light. Being in the midst of it, its light could evidently not be observed as an external thing: it would be confounded with that faint illumina- tion arising from the intermingling of the rays of all the stars, which somewhat brightens the dark ground of our skies; and must have remained unknown, but for another mode of experiment. In note A, at the close of the vol- ume, where the planetary phenomena are rapidly sur- veyed, I have shown how the permanence of the orbit of each planet depends upon the perfect balance of two forces or tendencies, viz., the attractive power of the sun and that tendency to fly from the centre, which follows from the motion of bodies being naturally in straight lines, and whose energy depends, in such case, upon the rapid- ity of the body's motion. If the power of either of those balanced forces be diminished, it is clear that the authority of the other will prevail. Relax Gravity, therefore, and re-" NEBULO US FLUID—-COMETS. \ 89 the planet will recede from the sun, and its orbit widen until a balance is restored. In the same manner, diminish the rapidity of the body's motion, and, as the centrifugal force will be diminished by the same act, Gravity will prevail;-so that the body's orbit will be contracted or drawn in. Now, if a nebulous fluid is diffused through the planetary spaces, every body which moves through it must experience resistance and be retarded as we are by the atmosphere, when riding at a rapid pace; and we would thus expect to trace the ether's existence in the fact of the planetary orbits gradually drawing in, and the re- volving bodies approaching the sun. Unhappily, how- ever, for this only mode of observation left, the planets are too dense, too large to be of service in so delicate an inquiry. However light and thin the ether, there is no doubt that it must and will influence even their motions; but perhaps, by a quantity so small, that the accumulation of the perturbations arising from it during the whole period of accurate astronomy, would not render it percep- tible. No trace of such influence, indeed, is yet found in our planetary tables; and astronomers would have been left in regard of the whole subject to conjectures, which, however plausible, had yet no actual or experimental ground, unless for a remarkable and certainly an unlook- ed-for occurrence. Until recently, astronomical science has not been able to present a complete and minutely.ac- curate view of the orbit of any comet. The general cha- racter of the orbits of these bodies, and the important ele- ments, at least of one of them, have bein known since the time of the celebrated Halley; but this philosopher knew nothing further than the general elements; and no orbit was laid down with exactness sufficient for the above pur- pose, until Encke of Berlin examined with so mnch accu- racy the conditions of a body—if a thing so small and vaporous merits the appellation—which completes its eccentric course around the sun in 35 years. Now, it appears by observation, that this comet is approaching the sun ;—on every successive appearance, we find its orbit somewhat contracted, and there is reason to believe that the contraction will go on until it is either absorbed in that luminary, or altogether dissipated by his beams. And after vainly searching for some other cause, inquirers 90 PHENOMEN A OF THE SUN. are nearly unanimous in referring this extraordinary and hitherto unparalelled change, to a RESISTING MEDIUM or ETHER occupying the planetary spaces. “I cannot but express my belief,” says Professor Airy, “that the principal part of the theory, viz. an effect exactly similar to that which a resisting medium would produce, is per- fectly established by the reasoning in Encke's memoir;” and similar opinions have been offered by other great au- thorities. That the sun, then, has a widely diffused nebu- lous atmosphere—extending far beyond the limits of the Zodiacal Light, and if not beyond, at least deep into the planetary spaces—an atmosphere of which that light may merely be the densest portion is at length rested on a high degree of probability: and how singular is it that we should have been guided to a truth so remote and difficult— one concerning which the grander phenomena of our sys- tem are silent, by the motions of a wandering object, in comparison with whose ethereal nature, even one of these light flocculi or flakes of cloud, which scarce stain the sky of a summer evening, is heavy and substantial! Even thus harmonious is the universe ! And seeing the perfect continuity of that golden line of order, which unites its mightiest phenomena with its least, so that the motions of a speck of dust may illustrate causes adequate to generate worlds,--what achievement is too high to be hoped for future discovery, and why may not a time arrive, when, in return for man's close observation, and unwearied ques- tioning of nature, the darkest of those speculations in which we have just been indulging, shall be doubtless and ven- turous no more? If the consideration of these circumstances has sufficed to destroy your natural repugnance to the resolution of our effulgent sun into a Nebula, you will be prepared to start the next question—the question as to the capacity of the Hypothesis, that the sum sprung from such a mass, to explain the most remarkable feature of his Being, viz. his rotation round an axis. When we reflect on the Solar or any other nebula in the act of condensing, it appears that the phenomenon consists in a flow or rush of the nebulous matter from all sides towards a central region; which is virtually equi- CAUSE OF ROTATORY MOTION. 9 | valent, in a mechanical point of view, to what we witness. so frequently, both on a small and large scale—the meet- ing and intermingling of opposite gentle currents of water. Now what do we find on occasion of such a meeting 3 Herschel's keen glance lighted at once on this simple phenomenon, and drew from it the secret of one of the most fertile processes of nature | In almost no case do streams meet and intermingle, without occasioning where they intermingle, a dimple or whirlpool; and, in fact, it is barely possible that such a flow of matter from opposite sides could be so micely balanced in any case, that the opposite momenta or floods would neutralize each other, and produce a condition of central rest. In this circumstance, them—in the whirlpool to be expected where the Nebulous floods meet—is the obscure and sim- ple germ of rotatory movement. The very act of the con- densation of the gaseous matter as it flows towards a cen- tral district, almost necessitates the commencement of a process, which, though slow and vague at first, has, it will be found, the inherent power of reaching a perfect and definite condition, and from which consequences ultimately issue, not less various and astonishing than the foliage and stature of the noble tree, considered as the development of an insignificant seed. - You will have no difficulty in perceiving, that—the whirlpool motion once originated—there is an inherent power in matter, under such circumstances, to evolve finally a definite rotation of considerable velocity. It is a general law or fact, that if a body is subjected to two mov- ing influences acting in different directions, it obeys both, or moves in obedience to each, as if the other did not exist. For instance, let a person in a boat start from A, 92 ROTATORY MOTION ILLUSTRATED. with the intention of pushing his boat right across a stream; and suppose, that in the time he would occupy in rowing from A to B, if the water were still, the power of the stream would carry him from A to C if he did not Tow at all;-the question is, how his boat will actually move 2 Now, all experience tells us, that if he merely rows right across—pushing his boat from the bank A towards B, with its side invariably to the stream, he will, previous to reaching the opposite bank, have been carried down by the current precisely as far as if his boat had merely floated; so that he will reach the bank at D, im- mediately opposite C, and his boat will have partaken at once of the two motions or influences impressed upon it. This law, as I have said, is general; it holds in every case where a body is under the influence of two moving powers; and the consequences of its action in a condens- ing nebula, connot be mistaken. Let the subjoined sketch NA represent a section of a circular nebula, revolving about the central region C, and in which condensation is per- manently going on. It is evident that the particle at A, in consequence of the whirlpool, moves from A to B, while the particle at A', only moves from A' to B'; but, as the attractive power, by drawing the first particle from A to A', cannot, by the foregoing principle, diminish its circular velocity, the result of such condensation will be the attaching to A' of another particle A, whose circular velocity is greater than its own. Now, the permanent consequence is manifest. If two balls, A and B for in- B ...- - * e– \ WWIHIRL POOL MOTION. 93 stance, are moving forward with different velocities, A much faster than B, what will follow when A overtakes B? Certainly an acceleration of B's motion, and a retar- dation of A's; and the two together will, after contact, move on much more rapidly than at B's former rate : so that, by the very act of A (see first Fig. On previous page) being brought into union with A', the rotatory velocity of A" would be augmented; and if the whole outer circle A B, &c., were attracted towards the inner circle of mat- ter A'B', &c., that inner circle would accordingly rotate more rapidly than before, and the velocity of the rotation of the entire nebula must therefore be increased. Physical objections, I am aware, may be taken to this explana- tion;–I propose it merely as a popular one: but it indi- cates, nevertheless, the principle which assures us that the condensation of a diffused and comparatively slow whirl- pool cannot take place without a great and growing in- crease in the velocity of its rotation, inasmuch as the mo- mentum or amount of the rolatory force, must, in all its stages and conditions, continue the same. And thus, if you have followed me, you see how, out of phenomena the rudest and most unpromising, and by the simplest laws of nature—those which guide the facts of every-day experience,—even that stupendous rotation might be gene- rated—a rotation whose discovery was one of the first achievements of the telescope, and which, all who know Nature ought to be assured, does not stand by itself, or as an independent fact, but is a cosmical phenomenon of wide significancy, and closely, however mysteriously, related with the whole scheme and progress of Things.” II. Our conclusions are already of great importance, and will lead us far. Not only are we now able to look upon these myriads of single sums, as having come—as probably at least as our own luminary—from the womb * The velocity of the resulting rotation will manifestly depend on the magnitude and condition of the original Nebula; so that we would expect to find no uniformity of period in the rotations of the stars—an expectation perhaps verified in the phenomena of the vari- able orbs. The probable variations of size in the original Nebulae, also leads us to the supposition that there is probably a very great variety in the magnitude of the resulting stars. * 94 - MOTIONS OF CLUSTER S. of the Nebulae; but we have likewise generalized the phenomenon of rotation by generalizing its cause, inas- much as the foregoing demonstration applies, to any con densing mass: and from the vantage ground of this far- ther and almost unexpected insight into phenomena, we can proceed with some confidence to take cognizance of the general fact next in order of simplicity;-viz. that evolved by Herschel's fine induction from the existing statistics of the Heavens—the law of the revolving motions of stars associated in limited and compressed clusters. The solution of this great and interesting law afforded by our Hypothesis, I cannot term less than picturesque, it ex- cites instantaneously our surprise and admiration. Have you ever walked in a mood of tranquil thought along the side of a quiet rivel, whose waving banks reflect a thou- sand currents, by the intermingling of which, numerous dimples or whirlpools are produced—their easy glide only marking the river's stillness? Have you seen these dimples follow and pursue each other as if in gambol, or watched the phenomenon of the near approach of two or three ? Then have you witnessed the secret of the mys- tery of the double and triple stars When one of these dimples reaches the verge of another, the two begin to re- volve around each other; and in fact they must, on ap- proximation, act mpon each other as two wheels, so that a revolution of each around the other must immediately su- pervene, and increase in rapidity, until, by external pres- sure, they are forced into one. Plate XVII., in which Double Nebulae are presented in various stages, enables us to apply this illustration. If the single nuclei are ro- tating, as we are now almost entitled to say they must be, it is precisely a case of two contiguous whirlpools; and how could revolutionary motion be prevented ? Two such masses in approximate contact must originate such a motion: as the principle of gravity draws the nuclei nearer each other, the velocity of revolution will mani- festly increase; and the two bodies will constitute them- selves into a stable system when the rapidity of revolution suffices to counterbalance their mutual attraction. The case is manifestly the same in instances of three, four, or more nuclei, formed in the immediate neighborhood of NATURE OF CRIEATION, - 95 each other, or out of one such mass as Fig. 1. in the same plate: so that now we have not only a CASUAL so- lution of Herschel's remarkable prophecy, but also an intimation that the modes of revolution of small clusters, may be as varied and fantastic as the multifarious revolu- tions of associated dimples in a stream. To deduce from the dynamical laws which govern the interlaced motions of these tiny whirlpools, the classes of related orbits whose discovery may be expected in the sky, were in the mean time premature;—the more so that our conjectures con- cerning this peculiarity in the play of the Nebular hypo- thesis, present a point of experimental but unexplored verification. All known double Nebula, should be sedu. lously watched; although they may move slowly, still their motions might in some instances be detected;—a positive discovery which I do not hesitate to allege would not be second in interest to that which has immortalized our age—the dircovery of the actual motions of the dou- ble stars . . . I am not sure that the portion of the neb- ular speculation over which I have just gone, is not in my eyes the most engrossing of the whole of it, for it points emphatically to a moral I am i. anxious to im- press. We are all too easily inclined to look on creation as made up of isolated parts—of independent or individual classes of beings, and to regard Nature as we do a case of botanical or mineralogical boxes; so that it requires a fact as striking as the identification of the Stellar motions of REvolution with those of RotATION, to startle us from the habitual error, and to bring us to right views of that stupendous or DER within which we live, and of which our own beings constitute a part. . The unity of things—their independence—their adjusted relationships, are proclaimed by every department of the Universe. I deny not that different laws may exist; nay, they must,-- for it is only by the commingling of Opposites that Vari- ety and Progress can be produced; but all is not opposi- tion which seems so, and most of what we divide and par- cel out into isolated bundles, is nothing other than the parts of the same grand scheme. º has taught this for ages—it is, in fact, the secret of her life; for she aims to gather up all * and to present the Uni- \ 96 ROT ATING NEBU L E. ! verse united, compact, tending to one end—a type of its August CREATOR. III. We are not yet done with tracing the wide and wonderful consequences of the Rotation of Solar Orbs. Singular though it appear, the next attribute of the Sun, —the fact of his being surrounded by PLANETs, springs necessarily out of his Rotation; from which we likewise deduce the whole form and mechanism of the system which belongs to him. If the discussions I shall present to you are somewhat more difficult and tedious than the preceding, I believe they will yet reward your attention, for we are also about to demonstrate that law, at which on several occasions I have hinted—the necessary exist- ence of planets around every star in which the elemen- tary principles of matter, as we know it, are freely ope- Tatl ve. - * 1. The preservation and permanence of the place of a point on the surface of a rotating body depends, as I have said, on the circumstance that the centrifugal force is not greater than the power of the central attraction. Thé inevitable consequence of an excess of the former is seen in simple operation, in a common phenomenon. It is known to Mechanics, that a grindstone may be made to revolve with a rapidity sufficient to cause splinters to fly from its rim, and even the whole rim to break in pieces— indicating that the centrifugal force of the rim with that velocity, more than counterbalances the mutual attraction or cohesion of the particles of the stone. Now, if the rim, instead of being formed of brittle stone, had consist- ed of an elastic belt, say of caoutchouc, what would re- sult in such a case? Clearly a separation of the rhm from the mass of the rotating body—it would expand somewhat, just as the orbit of a planet in a similar posi- tion; and, if other circumstances permitted, it would re- volve around the stone as a separate ring at a distance where the balance or equilibrium of the forces would be restored. Plate XXII will enable us to apply these considerations to the case of a condensing and therefore Totating Nebula with striking effect. Fix your atten- I'll NXll. FORMATION OF PLANETS. 97 tion on Fig. 1. We have already seen that causes con- tinually operate to increase the velocity of the Nebula's rotation; but when this velocity in any case became so great that the centrifugal power of the exterior portion or ring just balanced the attraction exercised over it by the mass of the Nebula, that ring would necessarily assume an independent character, and acquire, so to speak, a self- sub-sustaining power; it would therefore be abandoned by the main or parent mass at the next stage of condensation, and left as a distinct portion of matter revolving in som E For M around the central body. There is no doubt what- ever of the mechanical principles on which these infer- ences rest; and it is equally certain that there are almost infinite chances against the condensation of any large or original Nebula, without the occurrence of circumstances which would throw off numbers of such rings; so that, in a more advanced condition, every such mass might (if the forms of the thrown off rings had not altered) present the appearance of the second figure in Plate XXII., a large central nucleus, with subservient rota- ting ammuli, composed of quantities of matter necessarily very small when compared with the main body. Here, then, have we our first idea of the origination of planetary—or of quantities of parasitic revolving matter; and the question fiext arises, what forms would these rings probably ultimately assume? There are three possible forms. 1. The mass, if tolerably equable in its original constitution, and undisturbed from without, might con- dense as it is, or into a rotating so LID RING ; but the chances against such a result are so numerous, that we would expect the phenomenon to be very rare in the Uni- verse. 2. If the mass broke up or separated while con- densing—as its own internal irregularities would in all probability constrain it to do — it might divide into a number of portions so equal in attractive energy that none of them would have any tendency to coalesce with, or fall into the others; so that the ring would ultimately by- transformed into a number of distinct small solid bodies, revolving around the central mass at nearly the same dis- tance from it. These bodies, it is clear, would in their final state be spherical or round planets; and although 98 º For MATION OF SATELLITEs. ' not so evident, it is yet mechanically certain, that they would necessarily rotate on their aſces in the direction of their revolutions. 3. Even this second supposition, how- ever, is not a very propable one, inasmuch as its essential condition—the attraction of the mass of the ring towards equally balanced centres—could, in the nature of things, occur but rarely. By far the likeliest, result is the divi- sion of the ring into nuclei of unequal power—the larger of which would, by its superior attraction, assume the others into its mass, the whole solidifying into one con- siderable globe. Such globes would likewise invariably follow the law of rotation above specified; and every one of these secondary masses might, during the phenomena of its subsequent condensation and augmenting velocity of rotation, throw off rings corresponding in all respects to those around the primary mucleus, which condensing in their turn, and according to the foregoing laws, would form solid ammuli and Satellites. How exact is the correspondence of these general re- sults with the character of the bodies in our solar system 1. We have a central massive globe, with subservient globes engirdling him at various distances, and of magni- tudes very inferior to his. 2. The great proportion of the planets which compose our luminary's cortege, belongs in strict accordance with theory, to the last of the three defined classes of forms into which a ring might break up. MERCURy, VENUs, the EARTH, MARS, JUPITER, SATURN, URANUs, are single globes, revolving in orbits of their own, and around some of them are dependent satellites. 3. In one instance only, does the ring seem to have divided into equally balanced parts—I allude to the four small planets, those ASTERIODs between Mars and Jupiter, which have nearly a common orbit, or which revolve at almost the same distance from the sun : and 4. We have, also, in one solitary instance, a specimen of that most singular of cosmical appearances—AN ORI- GINAL RING, solidified in its pristine condition, and re- volving around the planet SATURN.” * It is not unlikely that there are many other very small bodies which have come into being in the same manner as the others, re- volving in various and disturbed orbits, within our planetary spaces. * COINCIDENCE OF PRO OF. 99 2. But, although it thus accounts for the origin of our system of individual bodies, the hypothesis must be tested by a still severer criticism, and reconciled with the me- chanism of the entire system. First : It must yield a law accounting for the relation of the velocity of each planet to its distance; it must shew that the velocities, or times of the revolution of the several planets, are consistent with the account given of their origin. Now the inquiry which contains the reply to this query is not difficult, and has lately been taken up and completed by a young French geometer. The velo- cities of the several planets should clearly coincide with the period occupied by the sun in rotating on its axis at the time when his atmosphere extended to their present orbits. Now the times necessarily occupied by the sun in rotating in these earlier states, are calculable ; and we find the most singular coincidence of theory with obser- vation. Each planet revolves at present nearly in the time in which he must have rotated when the correspond- ing outer zone of his atmosphere was abandoned—a cir- cumstance which M. Compte considers as bestowing almost demonstrative evidence on the Nebular cosmogony. I have said nearly, for the coincidence is not complete; the calculated time of the ring being shorter than the true time of the planet by about 1–45th part of the latter; but this difference, so far from overthrowing the presumption arising from the close correspondence, only opens more engrossing questions. The difference between the two periods must have originated in some laws and definite actions, although they are yet unknown; and will bear some proportion to the time which has elapsed since each planet was abandoned. Future analysis will unquestionably detect these laws; from which, the de- duction of the epoch of the actual origin of the parent Meteors, or falling stars, are now generally believed to be most easily accounted for, by supposing them bodies of this sort, drawn within the earth's atmosphere by attraction, and there ignited. The annual occurrence of a shower of meteors in the month of Novem- ber, distinctly intimates the existence of an unexplained astronomi- cal phenomenon; because, by being connected with the ecliptic and a particular season of the year, it is connected with the position of the earth in its orbit. - 100 LAWS OF PLANETARY MOTION. ring of any planetary body would not be arduous, and we should thus be able to construct an actual chronology of the formations in our System - Secondly, There is a signal peculiarity and co-ordina- tion in the arrangements of the motions of our planetary bodies, whose origin must be unfolded. The planets, without exception, move around the sun in ovals differing little from circles, and never far re- moved from the plane passing through the sum's equator; they all revolve in these orbits in the direction of the sun's rotation on his axis; they rotate on their axes in the same direction, and—excepting what we have been told concerning the still enigmatical and but partially known body, Uranus—the whole Satellites, including the rings of Saturn, revolve around the primary planets also in that direction; nor are the rotations of these se- condary bodies, so far as they are known, subject to a different law. Now, these phenomena receive no ex- planation from what we usually term the law of gravita- tion, inasmuch as gravitation could sustain systems dis- tinguished by no such conditions,—nay, it actually does so, for the comets are free from all these laws; they move in very eccentric orbits, often very far removed from the plane of the sun's equator, and their motions are as often retrograde as direct. Most fortunate it was that an inquiry baffling even the resolving power of gravity, and thus profounder than any undertaken heretofore, fell into the hands of a philosopher whose knowledge of celestial me- chanism was then complete, and whose capacity to trace elementary laws to their remotest consequence, has never been surpassed It occurred at once to the illustrious LAPLACE, that the ordinary operation of Gravity is to sustain or regulate systems which have been brought into being; and that the higher conditions of which 1 have spoken, pertain directly to the manner of our sys- tem's origin; nor did he meditate long ere the splendid speculation I have detailed arose in full maturity in his mind, and connected itself with the revelations men were at that time first receiving from the telescopes of Herschel. Observe how intimately the system of the generation from Tings, co-ordinates with these constituent phenomena. BUFFon's THEORY. 101 The rings in the first instance must be circular, and thrown off at the sun's equator where the velocity of rotation, and therefore the centrifugal force, is the greatest; the bodies resulting from them must revolve all in one direction, and with velocities corresponding to the velocity of the Ne- bula at the period of their separation; the separate and consolidated masses resulting from their destruction must, as stated, rotate on axes in the direction of their revolution; and finally, all Satellites subsequently formed must both revolve and rotate according to the same order! The Cosmogony has thus every mark of truth: its roots are seen in the Heavens, and they appear to go through every mook and alley of solar and planetary arrangements, not only explaining them, but comprehending their variety, and deducing the whole from one grand principle. How different the Cosmogony of BUFFON.—a man to whom genius was never wanting, who brightened every subject on which he touched, and kindled every mind which approached him, because, although with faculties im- perfectly balanced, he lived and had his being amid The richest and rarest qualities of the philosophic spirit, how different and wholly fantastic his idea that planets were chips struck off the sun by the collision of comets Not one of the fundamental conditions of our system's mechanism could be explained by this wild and reck- less imagination, whereas Laplace's bold and brilliant induction (may I not now so name it?) includes and resolves all! The theory is so beautiful and perfect, that perhaps we lilight have assumed it to be univer. sal, and asserted that every planet springing out of rota- tion, and engirdling each of those infinite orbs, must be subjected to the chief laws which control the earth—had not presumption been checked by one emphatic indication. If, as we are informed, the two least problematical Satel- lites of Uranus have retrograde motions," i. e. if they move in directions opposite to the general one, there must be some influence or law capable of checking, in so far, * These are the only two satellites of this remote body which have been seen since the time of Sir William Herschel. It is scarcely to be doubted that their motions are retrograde, and in orbits highly in- clined to the ecliptic. --- 102 - REFLECTIONS. and modifying the operations indicated by the Nebular Cosmogony; and this intimation reaches us from the farthest verge of our system—that confine where novel. external actions would be the most sensibly felt. What- ever this influence is, it cannot invalidate the theory of Laplace. The laws of mature never destroy, but only modify each other, just as the systems of circular waves diffused from two centres in a pool, intermingle and affect. each other's undulations—each spreading meanwhile out to the extreme limits of the sphere. - We have been advancing very rapidly—let us pause now and look back on the grand perspective below us. We set out by asking, can the Nebular Hypothesis explain the stars 2 Somewhat indeed remains to be fathomed, and phenomena apparently disparate may still be found in the sky; yet, short way as we have gone, every one of the grand features of the stars—facts, which but to mark, have often worthily conferred deathless fame —are seen in union and harmony the most unexpected, pro- ceeding hand in hand from the bosom of previous night, and going through untold ages in singular companion- ship, as if we had even attained the privilege of witness- ing the arranging influence of that Dove Spirit which erst brooded over chaos. It is indeed an impressive spec- tacle! Who can ascend so far up that vast chain which unites the eternal past with the fleeting present; who— to go no higher—can dwell on the idea of our Sun being born from one of those dim nebulae, order growing with- in him by effect of law, and the worlds he illumines and sustains, springing gradually into being, without en- grossing emotions | Sometimes, on contemplating this mighty progression, and thinking of the changes, visible and concealed, which must have marked the advance of an organization so majestic; asking, too, what is man, save a transient organization, with whose progress the educa- tion of a Spiritual Being has been for a moment connect- ed—I confess I have been so fanciful as to doubt whether those great and good men who endowed the stars with spiritual principles, ought to be deemed mistaken, whether that orb, during its fathomless evolutions, may 'MEANING AND ORIGIN OF LAW. 103 not have been the seat of a spIRITUAL Pot ENTATE, gifted with the glorious capacity to rise in knowledge, power, and beneficence, by experience of all the vast events of which he is the centre—whether we should not look upon these HosTs of HEAVEN, as something still more awful than inanimate worlds fitted to sustain a Life like ours ? Far as our ken has reached between us and the HIGHEST there is still vastness and mystery —sometimes to take wing beyond terrestial precincts, perhaps, is not wholly forbidden; provided we go with unsandalled feet, as if on Holy ground. - Apart however from all speculation,-surely the view of an actual order whose beginnings are hidin what seems in our eye mothing less than Eternity, cannot but elevate our thoughts of that BEING, who, amid change, is alone unchangeable—whose glance reaches from the beginning to the end—and whose presence occupies all things | If uneasy feelings are suggested, and I have heard of such, by the idea of a process which may appear to substitute progress for creation, and place law in the room of pro- vidence, their origin lies in the misconception of a name. LAw of itself is no substantive or independent power; no causal influence sprung of blind necessity, which carries on events of its own will and energies without command. Separated from connection with an ARRANGER in refer- ence to whose mind alone, and as expressive of the Crea- tive Idea it can be connected with the notion of control— Law is a mere name for a long order—an order unorigi- mated, unupheld, unsubstantial, whose floor sounds hollow beneath the tread, and whose spaces are all void; an order hanging tremblingly over nothingness, and of which every constituent—every thing and creature fails not to beseech incessantly for a substance and substratum in the idea of on E—w Ho LIVETH FOREVER There are certain supplementary presumptions on be- half of the Nebular Hypothesis in its application to the organization of the sun, which, although out of the line of direct demonstration, are too interesting and important to be omitted here. Comprehending these remote or con- stituent phenomena of our planetary system, and therein dividing itself from all other cosmogonies, it will appear, 9 104 NEw To N's AND LAGRANGE's VIEws, besides, in exquisite accordance with all known “origin- ating principles,” when we understand the especial play and influence of these phenomena on our system's destiny. If you have rightly apprehended the cause of the stability of a planet's orbit—thé balance, viz. of its centrifugal force, and the power of the sun's attraction—you will see that the influence of any third body upon the planet might disturb this permanence. But the idea of gravity had not long been present to Newton's mind, before he saw that as it is a universal, power—a power diffused from every particle of matter within the system, enabling not only the sun to attract the planets, but each planet also to attract every other; so that upon each individual body— the Earth for example—there are playing, as well as the sum's attraction, the combined and ever-varying attrac- tions of its shifting companions. It appeared to our ad- mirable countryman, that the path of no planet could therefore be perfectly stable, but on the contrary, that every orbit must be constantly moved somewhat from its place by these unsteady influences; and he thought that the disturbances thus introduced would abate the symme- try of existing arrangements, and in all likelihood ensure their destruction by one irregular shock. The dissipation of Newton's fear was reserved for that age whose termi- nations we are still touching; when the subtile analysis of the illustrious LAGRANGE instructed us that every one of the disturbances referred to must be PERIODICAL or oscillatory, i. e. if the moon is now approaching the earth, or her orbit drawing in, a time must come when that ap- proach will cease, and when an opposite action, or a retro- grading motion will take place, which also will be stopped in subsequent ages by a superior limit: and so of all other perturbations. Now this truth results from the existence of these very constituent elements of owr system, which the Nebular Hypothesis alone comprehends ; for if the planets and satellites had not moved in the same direction, alike in their revolutions and rotations, and if the spheres within which they move had not approached to circles, and been comprised almost in the plane of the sun's equator— the periodicity would not have supervened, and no anti- dote had been found to Newton's sorrowful forebodings. THE DESIGN AND DECAY OF OUR SYSTEM. 105 It were pleasing here to arrest our progress and admire so signal an illustration of that beauty of design and bene- ficence of purpose visible in every portion of the great chain of causes and effects; but passing the attractive theme we rather hasten to conclusions directly in view. Those constituent elements are thus the elements of the strength of planetary arrangements; and it is in closest connexion with them that we have found the originating cause of the whole planetary system. But in every de- partment of organized life—whether vegetable or animal —it is a law that in the progress of reproduction and growth, we have an especial adaptation to produce, or en- sure the existence of such essential circumstances, while the causes of the accidental ones are evanescent and of ir- regular action; and perhaps it is its fine accordance with this wide and striking analogy, its adaptations to that por- tion of planetary phenomena which, more than all others, must have sprung directly from the causes of our system's birth, that have gained for the theory of Laplace the respect of all, and the silent acquiescence of many As- tronolmerS. - Still farther;-the system, though strong, is not framed to be EveRLASTING ; and our Hypothesis also developes the mode of the certain decay and final dissolution of its arrangements. Remember the effects of the Solar Ether Although no mark of age has yet been recognized in the planetary paths, as sure as that filmy comet is drawing in its orbit, must they, too, approach the sun, and at the des- tined term of their separate existence, be resumed into his mass." The first indefinite germs of this great organiza- tion, provision for its long existence, and finally its shroud, are thus all involved in that master conception from which we can now survey the mechanisms . which we are And mark the nature of this decay. It comes, not as Newton thought, by accident, derangement or disease, but * It may be asked, does not this Ether rotate along with the plan- ets, and therefore not retard them 7. It must rotate somehow—the comets will one day discover that for us; but it cannot rotate with velocities corresponding to all the planets. Nay, the very ellipticity of the planetary orbits, small as this is, necessitates a retardation in every one of them, however the Ether may rotate. 106 NEW TON IN WORES SUPREME POW ER, through the midst of harmony; it is an easy consequence of the venerable power which first evolved us, infused our scheme with the spirit of life, and gave it structure and strength. Our supposed origin of the planets gave them and their satellites that kind of orbits, and that kind of rotation which produced their permanence; and the inhe- rence of this same Nebulous parentage, viz. the existence of an ether, leads gently to their decline. So dies Nature's umblemished child—the simple flower | | It bursts its sced, buds and blooms; and them, in unpained obedience, draws in its leaves and sinks into the lap of its Mother Earth. The idea of the ultimate dissolution of the solar system, has usually been felt as painful, and forcibly resisted by philosophers. When Newton saw no end to the derang. ing effect of the common planetary perturbations, he called for the special interference of the Almighty to avert the catastrophe; and great was the rejoicing when that recent Analyst descried a memorable power of conservation in our system's constituent phenomena; but after all, why should it be painfull Absolute permanence is visible no where around us, and the fact of change merely intimates, that, in the exhaustless womb of the future, unevolved wonders are in store. The phenomenon referred to would simply point to the close of one mighty cycle in the history of ſhe solar orb; the passing away of arrangements which have fulfilled their objects that they might be transformed into new. Thus is the periodic death of a plant perhaps the essential to its prolonged life, and when the individual dies and disappears, fresh and vigorous forms spring from the elements which composed it. Mark the Chrysalis It is the grave of the worm, but the cradle of the sunborn insect. The broken bowl will yet be healed and beauti- fied by the potter, and a Voice of joyful note will awaken, one day, even the silence of the Urn —Nay, what though all should pass? What though the close of this epoch in the history of the solar orb, should be accompanied, as some with a strange fondness have imagined, by the dissolution and disappearing of all these shining spheres? Then would our Universe not * ULTIMATE VIEW OF ALL THINGS, 107 have failed in its functions, but only been gathered up and rolled away, these functions being complete. That gor- geous material framework, wherewith the Eternal hath adorned and varied the abysses of space, is only an instru- ment by which the myriads of spirits borne upon its orbs, may be told of their origin, and educated for more exalted being; and a time may come, when the veil can be drawn aside—when spirit shall converse directly with spirit, and the creature gaze without hindrance on the effulgent face of its Creator: but even them—no, not in that manhood or full maturity of being, will our fretted vault be forgotten, or its pure inhabitants permitted to drop away. Their reality may have passed, but their remembrance will live for ever. The warm relationships of dependent childhood, are only the tenderer and the more hallowed, that the grave has enclosed and embalmed their objects; and no height of excellence, no extent of future greatness, will ever obscure the vividness of that frail but loved infancy, in which, as now, we walked upon the beauteous earth, and fondly gazed upon these far-off orbs—deeming that they whisper from their bright abodes the welcome tidings of Man's immortal destiny. 9* * (108) LETTER V III. SPECULATION. IF our desire of knowledge did not quicken as its sphere expands, or if Man, so long as one eminence is unsur- mounted, could lay himself down in peace, satisfied with the view of the vastness and variety which already stretch out beneath him, doubtless our task had now ended, and the volume of Astronomy might have been closed. But Desire, happily insatiable, has no confine on this side of the Infinite; and no sooner have we reached the elevation of one thought or idea which resolves some large portion of the unknown, than ambition is fired afresh, and specula- tion never at rest, takes flight toward remoter regions. In the present instance, indeed, there is every encou- :agement to further adventurous inquiry. The Nebular Hypothesis, in its relations to the planetary system, may be termed complete;—it comprehends its beginnings, es- tablishes those elements on which its duration depends, and exhibits the causes and mode of its ultimate transition into a novel form; and thus—surveying it from its com- mencement to its close—we are as if in possession of that primeval Creative Thought which originated our system and planned and circumscribed its destiny. Now, in re- ference to one of these epochs, our Hypothesis seems to hold equal connexion with the whole contents of the Heavens,—the epoch, viz. of their origin; and is it—as a conclusion of our task—too daring to fancy that likewise in their progression under the control of law from primi- tive chaos, principles are evolved which regulate the ex- isting distribution of stars into firmaments, which have determined the form of the present condition ofthe Universe, and from which new forms will issue unceasingly, until, STABILITY OF THE FIR MAMENT. 109 as with the planets, the hour of final transmutation comes, and the cycle of their existence is complete? In endeavor- ing to pursue such an inquiry—supported, as we are only by a few very remote hints from observation—there is need of all our cautiousness; nor can we hope to obtain farther than the most general idea of what DEITY keeps in store for those majestic stellar arrangements. I. Knowing as yet only the fact, that clusters of two, three, or more orbs, provided with all the machinery of rotation and revolution, may spring from the regular con- densation of a nebular around several nuclei, we cannot form an idea how, as in the planetary system, the conserva- tive principles of the machinery º be evolved regularly and without constraint, during the formation of the cluster; nor indeed is our philosophy, boasted as it is, capable of showing of what nature such principles are. Doubtless in those nobler systems, as well as among the arrange- ments of our small worlds, the elements of strength, secu- rity against shock, and fine internal compensations and adjustments, grow with them from chaos—precisely as the great oak tree has a breathing and circulating machi- nery, fitted for action during a thousand years, while those of the blades at its feet decay and die aſter a brief summer; but we are not yet in a condition even to undertake the question, and the thought of it only stirs us with the hope of wonderful revelations to come—of brilliant records for the future pages of science. Taking, however, a very simple case, that of a regular globular or oval cluster, it is not difficult to imagine one mode by which it might be fitted for absolute and everlasting stability. We have in- deed only to suppose that every sun within it describes an oval or ellipsis around the general centre of attraction, and all in the same time. In whatever direction the bodies 'might move, whether direct or retrograde, in the samg plane or across each other's orbits, such a cluster would be permanent; and during all time its orbs would thus revolve, arriving together after some vast interval at the exact position from which they departed,—which interval would be the great year, the amnus magnus of the cluster. Now, even although no such precise motions should any 1 10 CONDITIONS OF STABILITY. where exist, this fact is extremely valuable. It illustrates the possibility of the existence of motions among the orbs of these brilliant masses, by whose relationships the in- fluence of gravity might be permanently withstood; and it permits the conception, that whether or not that influ- ence is absolutely withstood there, still such arrangements may exist, and that these clusters may be endowed with adjustments not less efficient and beautiful than the con- stituent arrangements of our own system, by which har- mony is preserved in the face of change, and strength dur- ing a long decline. - Such a condition of stability—arising, as we will pro- bably some time discover, also out of the very process of condensation—would not, however, be permanent or ab- solute, unless accompanied by an absence of all resisting causes. Should retarding causes exist, the recurrence of the Annus Magnus would no longer find the different orbs in their first position, but to a certain amount nearer the centre of attraction, and the whole cluster somewhat compressed: so that if any remnant of ancient chaos still pervades the intervals of these orbs, compression must ensue, and the firmament must pass through all degrees of it, occupying ages in its mysterious growth towards some other form of being. The effect of such a nebulous ether would be exactly the same as the effect of the solar ether upon the planetary orbits, so that the speculation rests sºlely on the question of its existence. Perhaps the existence of a fluid so rare may never become a subject of actual or positive demonstration or experiment, unless im- deed, through something like those recent notions of M. STEINHEIL, which lead him to conjecture that the light of the stars does not reach us unimpaired, but that a quam- tity, in proportion to the remoteness of the star, is lost by passing through a certain intervening nebulous medium. Still it is fair and competent to ask, whether the form of existing clusters gives color to the hypothesis of their gradual decay, or the gradual approximation of their stars. The hypothesis would clearly induce us to expect a series of objects, beginning with a cluster of perfect regularity, in which various compressions will be exhibited, and upon which MUTABILITY is stamped. Now, this series SERIES 6F FIRMAMENTs. I 11 exists; if we would characterise the globular clusters we have resolved, and without reference to theory, it would be in language we have already used (see Letter V.,) and by their various compressions. These objects present a series quite umbroken; and they are in the exact condi- tion illustrated by Herschel when he compared them with plants in different stages of progress, from adolescence to proximate ripening (which in this case is decay)—pre- cisely as Laplace afterwards most aptly characterised the varying aspects of the Nebulae. It is not possible that these phenomena can be mere illusions. A real series is never meaningless; and where it seems so, we have as- suredly committed the error of assuming that to be a series between whose different facts or stages there is no con- mexion—where we have no evidence of an evolving or transmuting cause. - —How immense is the field of contemplation opened by these very simple considerations ! Even the larger forms of the Heavens are not stable ! Those globular masses at least, appear in process of growth, of ripening —they are congregating towards that nucleus, around which the new order of things is slowly up-growing, and where the mighty Orb, foretold by their progressing ag- gregation, is preparing to be born. I cannot avoid re- verting to the notion of Mr. Coleridge; what is this after all, save a prolongation of the condensing of a Nebula 2 Already some few of its particles have come together and formed its secondary stage; and now, that secondary stage, which we term a firmament, is passing into a third, where all the dispersed atoms will be gathered together, and lodged at the centre of the mass! We may venture even one step higher. If the suns of each firmament, which are but the congress of multitudes of atoms originally distinct, are related in this wise—may not some similar system and similar destiny characterise Systems of Firmaments 7 Perhaps in the mean while these ale also related, somehow as the stars in each clus- ter—slowly performing mighty revolutions, whose recur- rence constitutes the greatest Annus Magnus of Creation, the highest unit of existing Time. Probably the ele- | 12 I) ISSOLUTION OF THE MILKY WAY. ments of decay, or rather of change, are also amid this mechanism—probably all is passing, in a silence next to motionless—quietly as the leaf grows, towards some um- known consummation | The eye stretches in vain in the direction of the epochs thus foreshadowed,—they are epochs with which the duration of all we can imagine is utterly incommensurable; but yet their coming is sure; and by the existing forms and arrangements of matter their features are minutely preparing. II. It is fortunate for speculations like the foregoing, that within our own Firmament, aspects are distinguisha- ble not only sustaining them through a strong analogy, but even pioneering the way to yet bolder thoughts. Our milky zone has been already described as a ring for the most part isolated, in which the stars are very dense, and where the aggregating power has drawn them from the general mass, and by some curious operation, compressed them into a crowded girdle. But neither is this girdle uniform. In Letter W. I called your especial attention to its division, apparently into groups for the most part in- clining to the spherical form, and separated from each other by dark spaces like wrinkles of age. Sir William Herschel counted no less than 225 such groups or subor- dinate clusters, within the extent of it he examined; and as all these were of a kind to mark the action of gravity, he concluded the existence of a clustering power, drawing the stars of it into separate groups, a power which had broken up the uniformity of the Zone, and to whose irre- sistible power it was still exposed. “Hence,” says Her- schel, in one of those bold moments in which he fearless- ly traversed the infinities alike of past and future, “Hence may we be certain that the stars will there be graduall compressed through successive stages of accumulation, º they come up to what may be called the ripening period of the globular cluster and total insulation; from which it is evident that the Milky Way must forcibly be broken up, and cease to be a stratum of scattered stars.” “We may also,” he continues, in the same lofty mood, “draw an important additional conclusion from the gradual disso- lution of the Milky Way; for the state into which the in- PU N N lll . FORMING INTO CLUSTERS, 1 13 cessant action of the clustering power has brought it, is a kind of chronometer, that may be used to measure the time of its past and present existence; and although we do not know the rate and going of this mysterious chrono- meter, it is nevertheless certain, that since a breaking up of the parts of the Milky Way affords a proof that it cam- not last for ever, it equally bears witness that its past du- ration cannot be admitted to be infinite ſ” Surely the vision of these unfathomable changes—of the solemn march of the majestic Heavens from phase to phase, obe- diently fulfilling their awful destiny, will be lost on the heart of the adorer, unless when beneath the canopy on which their amnals are inscribed, it swells with that hu- mility which is the best homage to the Supreme ! Grounding on these sublime speculations, and taking into view some other facts, we are led to still remoter con- clusions. If the aggregation of stars in the Milky Way goes on, as it prognosticates, for Ages—the clusters, now with some intermission, forming its ring, will become isolated, and appear in the character of separate systems. But, if this happen in time future, may something similar not have happened in time past? And what other is the meaning of those Magellanic clouds in the south 2 Do they not exhibit a multitude of stars originally belonging to our system, in the very act of becoming isolated ? Referring once more to that approximate chart in Plate II, how irregular it is, how marrow in one direction, and how ragged its edges Can it be possible that masses of stars have been torn away from it in that direction, so that its thinness may simply indicate, that through the action of some irresistible cause, parts of it had there ripened sooner ? Singular to relate, it is precisely towards these thin sides, and almost immediately beyond them, that the vast mass of neighboring isolated clusters is found— clusters all spherical, and grouping together in extraordi- nary proximity. In Plate XXIII., you have part of the wing of VIRGo—a constellation situated near the shallow- est part of our firmament. Observe how crowded it is with groups—some of them, Nebulae indeed, but most of them small round clusters, exhibiting a marked degree of compression. In the regions on the opposite side, the 114 REFLECTIONS ON THE GREAT CHANGES. " same phenomenon recurs; from which, aided by specula- tion, we infer that the process of separation has gone on, and that the apparent breaking up of the Milky Way in our time, is simply a prolongation of part of the changes of the long past, to which our capricious firmament owes its irregular form. . - Collecting now these scattered gleams of truth, we rev- erently approach our last generalization. The separate firmaments which the telescope has descried and mapped down, show, as has been stated, even more emphatically than the groups in the Milky Way, the efficacy and pro- gress of a clustering power;-may not all have come originally from one homogeneous stratum or mass of stars, so that their present isolation—their separation und vari- ous groupings, are only the ongoings of the clock—the gigantic steps of the hand, by which Time records the days of the years of the existing mechanism of the Uni- verse ! Stupendous the conception, that these great Hea- vens—the Heavens we have deemed a synonym of the Infinite and Eternal, are nothing after all but one aspect in which matter is destined to present itself—their history like the birth, life, the death and dissolution of the fragile plant If this indeed is true—and on behalf of the con- ception we can marshal many probabilities, how immense. the sphere of real existence; how little can we ever know of it; at least, how much must be referred to that higher state of º expected eternity of sublime con- templation 1 What wonder bursts upon us! Take into consideration the influence of this vast mechanism over the minute ar- rangements of its subservient parts; observe the amount of most diverse organization, the almost infinite varieties of intelligence—wonderfully various, even within our lim- ited ken—which must be attached to the progress of the Heavens, growing with them as they grow, changing during every new phase, and sympathizing with their de- cline:—who then shall say that even the highest created spirit will ever exhaust the fulness of that volume which God has spread before us all, in illustration of his own Infinite Nature s * THE CONCLUSION. 1 15 —Suppose we are yet mistaken; suppose the Nebular Hypothesis, with all its grasp, not to be the true key to the mystery of the origin and destinies of things—what is gained—what new possession—by that course of bold conjecture on which we have ventured to embark 2 This, at least, is established on grounds not to be removed. In the vast Heavens, as well as among phenomena around us, all thmgs are in a state of change and PROGREss; there too—on the sky—in splendid hieroglyphics the truth is inscribed, that the grandest forms of present Being are only GERMs swelling and bursting with a life to come! And if the universal fabric is thus fixed and constituted, can we imagine that aught which it contains is unupheld by the same preserving law, that annihilation is a possi- bility real or virtual—the stoppage of the career of any advancing Being, while hospitable Infinitude remains? No 1 let the night fall; it prepares a dawn, when Man's weariness will have ceased, and his soul be refreshed and restored.—To CoME l—To every Creature these are words of Hope spoken in organ tone; our hearts suggest them, and the stars repeat them, and through the lnfinite, Aspiration wings its way, rejoicingly as an eagle follow- ing the sun. * Farewell } 0. N OT. E. S. NOTE A. THE SOLAR SYSTEM. The object and Scope of my treatise did not admit of the incor- poration with it even of a brief exposition of the phenomena of the solar system,--Our contemplations inclining us to regard the sun with his attendants as one unit, and presupposing, in some in- stances, a general acquaintance with the system. That no doubt may rest, however, over our speculations, because of the absence of a view of the system's details, I have thrown into this note an account of most of what is important on the subject.* 1. The solar system is composed of a majestic central luminary (whose mass is made up of matter like the earth—the atmosphere alone being luminous) and a number of small engirdling bodies, which revolve around him in various periods. Toys named orreries have generally been used to give an idea of this me. chanism: They are mere toys, often beautiful, but never instruc- tive ; nor indeed can they be otherwise, as you will learn from the statement of the distances, and comparative magnitudes of the several bodies, which I extract from Sir John Herschel's work : “Choose any well levelled field or bowling green. On it place a globe two feet diameter; this will represent the SUN ; MERCURY will be represented by a grain of mustard seed, on the circumfer- "ence of a circle 164 feet in diameter from its orbit; VENUs, a pea on a circle 284 feet in diameter; the EARTH, also a pea on a circle of 430 feet; MARs, a rather large pin's head on a circle of 654 feet; JUNO, CERES, VESTA, and PALLAs, grains of Sand in orbits of from 1000 to 1200 feet; JUPITER, a moderate sized orange, in a circle nearly half a mile across; SATURN, a small orange on a circle of four-fifths of a mile; and URANUs, a full sized cherry or small plum, upon the circumference of a circle more than a mile and a half in diameter.” Such are the contents and relative dimensions of the solar system • To the full discussion of all the phenomena of that system—belonging, so to speak, to our own homes, I have devoted the volume entitled, “The Phenomena of the Solar System.” i i8 Note A. 2. After the labor and observation and mistakes of ages, it be- came a settled point with instructed astronomers, that these small bodies, including the earth, move around the sun, which is the proper centre of the system; and the question then started, in what curves or paths do the planets revolve 4. A decisive answer was first elaborated by the illustrious JoBN KEPLER, who not only proved that they move in ellipses, or ovals, differing little from circles, but also established a law for the varying velocity of each planet when in different parts of its orbit, and the existence of a great relation between the distance and velocity of one planet, and the distance and velocity of any other. The three statements expressive of these general facts, are termed Kepler's Laws, and were our first accurate step towards a knowledge of the true me- chanisms of the Heavens, - 3. After Kepler NEWToN arose, and º the superstruc- ture founded by his great predecessor. is first achievement was the combining Kepler's three principles into one, and the constitution of dynamical astronomy. It is known as a universal fact, that bodies when set in motion tend to move in straight lines, and would so move for ever with uniform speed, provided no external force or influence interposed to deflect them from their natural paths. For instance, if the body A were set in mg- tion in the direction AB, it would move of itself in the straight line A B; and if we find it instead, moving in the curve A B', the inference is, that an external influence has deflected it, or turned it from its natural course; the effect of which influence in the case in the diagram, clearly is to have drawn the body (speak- ing approacimately) from B to B' in the time it would have occu- pied in moving from A to B. On these principles Newton re- solved the orbitual motions of the planets, by referring them to two forces—their natural tendency to move in straight lines through space, and an attractive or gravitating force drawing them to the centre of the sun; and by a refined and novel method of demonstration, he proved that the attractive force exercised by the sun over the different planets, is precisely the same power di- minishing in intensity in a certain manner according as the dis- tance of the planet increases. How simple did the celestial me- chanism thus become ! Each planet preserves its place and rolls through its appointed orbit, in consequence of the balanced action of two simple and regular forces. - - 4 NOTE B, * i 19 4. But Newton did not stop here. Meditating on the every-day phenomenon of the fall of a stone to the earth, it struck him that the existence af a ſorce was here indicated, efficient in drawing bodies towards the earth; and he daringly asked whether that force diminished according to the principle he had already de- tected, would not explain the gravitation of the Moon Q The dis- covery lay in the first suggestion of the idea, for the pursuit of it was not difficult. If, for instance, A B in the foregoing diagram, is the space the moon would move in a straight line in one second of time if left to her first natural impulse, and A B' her actual orbit, the quantity B B', which is quite susceptible of measure- ment, will show (approximately) the power of the earth’s attrac- tion over her in one second : and this, when placed beside the quantity through which a stone at the earth's surface falls in the same time, exhibits two motions having to each other the exact proportion required by the celestial law of gravity It is impos- sible to over-estimate the value of this momentous step. It imme- diately connected the celestial mechanism with terrestrial pheno- anema, establishing a first analogy between the Heavens and the Earth, and yielding an emphatic intimation of the great Unity of Things. Newton now generalized his first conception; announ- ced gravity as an universal property of matter—a law obeyed by every particle in reference to every other particle; and thus threw open the gates of the august Temple of the Universe. Subsequent astronomers have merely applied his comprehensive principle to the solution of cosmical phenomena. The orbits ef comets became at once intelligible. The figures of the planets were explained; and the determination of those fine influences, by which the planets affect each other, has constituted the chief em- ployment of dynamical science until the present day. It is one object of my little work to collect and arrange what traces have been ſound of the action of the same fundamental law among the external Stellar spaces. - NOTE B. THE or BITS OF THE DOUBLE STARs. The curious and inquisitive will naturally desire to obtain some notion of the actual size of the orbits of these double systems, or how far one star is distant from the other. Were we acquaint- ed with the distance of a binary system from the Earth or Sun, it would be quite easy to calculate its dimensions; but until that pre- vious knowledge is obtained, all information derived from this source must be purely conjectural. In the Amnuaire de Bureau 10% | 20 NOTE. B. des Longitudes, for 1834, M. ARAGo has, with his usual precision, detailed a very ingenious method, first pointed out by SAVARY which promises to afford accurate results on the subject. It de- pends upon the ſact that Light does not move instantaneously, but with a certain definite velocity, so that a specific time elapses be- tween the moment when the ray leaves a luminous body and that when it enters an eye. The following considerations will illus- trate the method I speak of Suppose ACBD the orbit of a dou- ble star, whose period is 200 years, and let the star be so distant from the earth when at the points A and B of its orbit, that its A. B light occupies two years in the first instance, and one year in the second, in passing toward us-what will be the effect of this upon the body's apparent motion ?' The result will be brought out most distinctly by calculation. Let the star be at A in the year.. ... 1800, It will be at B in . . . . . . . . . . . . . . . . . . 1900, And at A on its return in . . . . . . . . . . 2000 But since light occupies two years in arriving from A to the Earth, and one year in reaching us from B, The Star will be seen by us at A in... 1802, And at B in... . . . . . . . . . . . . . . . . . . . W901. S0 that it will seem to have performed one-half of its revolution, or to have gone through the half ACB of its orbit in ninety-ning years. Again, $o that it will seem to have revolved from B to A, or to have gone through the other half of its orbit BDA in one hundred and one !/ears. , But as it really does pass through these two arcs in pre- cisely the same time, this apparent difference of its periods must be ºwing to the size of its orbit as measured by the velocity of light, and in fact half the difference of the two numbers 101 and 99, or one year, is just the period occupied by light in traversing the lis- Not E c. 121 tance from A to B. The rule is quite general: observe the appa- rent times occupied by any revolving star, in going through the two halves of its orbit; and half the difference of these times will be the period in which light passes through the diameter of its orbit, and as the velocity of light is known, that diameter may therefore be computed in miles. The only obstacle to the general application of the method consists in the difficulty of noting exact- ly when the star is at the two opposite points of its orbit; but not- withstanding this difficulty it will yield results accurate within cer- tain limits. It is impossible to give too much credit to the inge- nuity of M. SAVARY. NOTE C. RELATION OF THE NEBULAR HYPOTHESIs To GEOLOGICAL CHANGE. I mean to crompress into this Note a few remarks at one time destined for the text, regarding the influence which may be exer- cised by the Nebular Hypothesis over the course of geological speculation. It does not require notice that our Hypothesis supplies the mat- ter of the planets, &c. in a condition sufficiently plastic to permit of its taking on the precise form in each case, which a solid of revolution ought to have ; nor indeed is this of any considerable moment, inasmuch as a great number of hypothelical cosmogo- mies offer similar ſacilities. When we go farther however, and trace the subsequent physical history of the bodies thus fashioned, we discover peculiar adaptations of our theory to the solution of problems which pure geology has not hitherto comprehended, and in regard of which that science must sooner or later borrow aid from Astronomy. The causes of geological change are two—an abrading and levelling cause, operating chiefly on the surface of our globe and through the agency of running water; and an ele- vating cause—that which has upheaved our mountain masses, and which is still efficient not only in partial volcanic actions, but over large tracts of territory, such as Sweden, which are slowly but gradually rising to a higher elevation. The difficulty in ge- ology is to discover the nature of this elevating cause, and it is with this question, as well as the mode of its operation in time past, that the conflict of geological theories is now concerned. We enter on the subject most easily and naturally through Dr. Daubeny's theory of Volcanoes. It is well known that the me- tallic bases of the earths, alkalis, -&c., inflame with considerable deflagration on contact with water; and this philosopher supposes that masses of these unoxidated metals lie beneath the surface of the earth in subterrancan reservoirs, to which water from the sur- face may find occasional access, and cause an explosion. Che- 1$22 NOTE. C. mital objections have been alleged against this theory, but they are of no cognency; and I believe that existing volcanic pheno- faena receive from it the best and most logical explanation which has yet been proposed. Let us now express this theory in gene- fa] language having a view to the Nebular Hypothesis. Our world is in that epoch of its being which, physically speaking, may be termcd the epoch of the fluidily of water, and we find that this water, which is the nebulous bed or stratum last condensed, exerts chemical actions upon the previously condensed bed of so violent a nature, that deflagration and explosion issue from their fortuitous meeting. How easily is this theory extended ! In its very nature it points to a general law; for what is going on with regard to these two most recent beds, may have supervened through all time past with any two strata which came in contact; the stra- tum B, in every stage, may have had chemical relations with the stratum A, so that a deflagrating and elevatºng power may have characterised every epoch of the history of every planet. When Daubeny's theory has received this general expression, the knot is cut which so much puzzles geologists of the present day, regarding the comparative extent of modern and ancient vol- canic forces. Mr. Lyell has achieved a great philosophical re- form in this department of inquiry, in boldly asserting it as a fun- damental tenet that we must philosophize upon the ground of ex- isting and known forces; but when he passes beyond this, and de- nies the possibility of the superior energy of these forces in former epochs, he oversteps his limits, and dogmatizes, because it is only when the nature of the origin of the force is comprehended, that we can ascertain whether or not it is plastic. The Nebular Hy- pothesis, as above, provides for its variability; and existing astro- nomical phenomena seem to establish that it is variable. It has long been known that the elevating cause—whatever it is, is not peculiar to this Earth;-its operations are seen in the Moon, in Venus, Mercury, and perhaps also in the Sun. Now, there is an order of age among these celestial bodies. Of the planets, the oldest is the farthest off, then comes Saturn, afterwards Jupiter, the four Asteroids, Mars, the Earth, Venus, Mercury; and the Satellites considered as complete worlds, are perhaps the most re- cent of all. The inspection of the different planets then, shows us this elevating cause in operation in a considerable variety of epochs, and we find, that the more advanced or the older the planet, the less NOTE D. 123 rugged or mountainous it is, the less energetic this shattering power. Saturn and Jupiter show no appearance of mountains; those of Venus, and in all probability of Mercury, are gigantic, when com- pared with the existing elevations of the Earth; and when we reach our own Moon, we find a picture of that torn, crateriform, and disturbed surface, which our own earth may have exhibited when the masses of existing mountains were thrown up, when the pin- nacles of the oldest ranges were unabraded, and the ruggedness of the valleys not yet smoothed away by the levelling power of the fluid which deposits and stratifies there, the detritus of the primary rocks. It is much to be wished that when a science arrives at its ulti- mate problems, we would no longer study it in isolated fashion, but look abroad through the Universe, for those relations which constitute it a part of the grand whole. NOTE D. LOCALITIES OF THE PRINCIPAL CLUSTERS AND NEBULAE. I subjoin a statement of the exact places of the more important objects represented in the foregoing plates; so that the possessors of good telescopes may have the opportunity of examining such as are within their reach. I give their Right Ascensions, and Declinations, by means of which their localities among the stars may easily be detected upon a celestial globe, and thus found without difficulty in the Heavens. Right Ascen. Declinations |H. M. Deg. Min. Plate I. Cluster in Hercules. . . . . . . . . . . . 16 35} 36 45 N. Plate III. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I3 22} 46 14°N. Plate V. Fig. 1 . . . . . . . . . . . . . . . . . . . . . . . . - 15 10 2 44 N. Fig. 2. . . . . . . . . . . . . . . . . . . . . . . . 21 25 1 34 S. Plate VI. Fig. 1. (counting from the left top of the line and passing across the page) 30 Doradus. . . . . . . . . . . . . . . . . . 5 39% 69 15 S. Fig. 2 . . . . . . . . . . . . . . . . . . . . . . . 0 16# 73 0 S. Fig. 3. . . . . . . . . . . . . . . . . . . . . . . 21 31 23 55 S. Fig. 4. . . . . . . . . . . . . . . . . . . . . . . 15 29 6 33 N. Plate VII . . . . . . . . . . . . © e º e º e º a tº . . . . . . . . 4 55 72 Rlate VIII. Fig. 1, faintest of the two rings, 20 9; § 3 N. Fig. 2, brightest of two rings, 18 47 32 49 N. Fig. 3, oblong hoop . . . . . . . . . . 2 12 41 35 N. Fig. 4, oval figure beside the hoop . . . . . . . . . . . . . . . . . . . . . 12 48 22 37 N. Fig. 5, large figure . . . . . . . . . . 19 52 22 16 N. 124 NOTE E. - Right Ascen. Declinations, - H. M. Deg. Min. Plate XIII. Nebula in Orion. . . . . . . . . . . . 5 27 5 30% Plate XIV. Fig. 1, Nebula in Andromeda, 0 33, 40 Plate XV. Fig. 2 . . . . . . . . . . . . . . . . . . . . . . 20 38% 30 6 N. Fig 3-------. . . . . . . . . . . . . . . . 20 31 3 N. Plate XVI . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 J 1 16 15 S. Plate XVII. Double Nebulae. . . . . . . . . . . . 9 22} 22 15 N. 7 15 s 29 49 N. 22 51 13 43 S. Two stars on faint bed of light. . . . . . 18 7 19 56 S. Plate XX. Nebulous stars. . . . . . . . . . . . . . 17 0 23 7 N. 19 40 50 6 N. - - 3 - 584 30 20 N. Plate XXI. Reticulated Form. . . . . . . . . . . 20 50 29 34 N. Nebulous matter connected with stars . . . . . . . . . . . . . . . . 12 51 35 47 N. •º. 20 56 11 24 N. 6 30 8 53 N. 8 464 54 25 N. [The following notes have been written and added by the publishers, with the view simply to g, we some additional interest to the work with general readers, by noticing a few particulars on one or two of the subjects treated by the author; and though they are too limited to afford rooun for any improvement of the work—and it was far from being ºxpected by the writer, if it were necessary—yet in soune inst unces, as with the Glossary, every fact on a subject of this nature, if unknown, will add something to its general interest.] L. D. CHAPIN TNOTE. E. The author here alludes to phenomena in Fossil Geology, which is intimately connected with the former history of our planet, and which has long interested the curious and scientific. Whatever the causes may have been in producing effects so remarkable as those disclosed by such and other fossil remains, the interest which they excite continues to increase as new specimens are re- vealed. That these prove extraordinary changes both in the phy- sical condition and temperature of the planet will not be doubted; and the primary cause of either or both of these circumstances is, therefore, at all times worthy of inquiry. The author refers to thcm more particularly as the result of a motion which is sup- posed to be sweeping our planetary system into far distant space; but that this was the cause of the 'fossil phenomena in question admits of doubt, and more especially as we find one more proba- NotE E. * 125 ble and nearer at hand. The immediate agents are presented by the remains themselves; and the primitive cause was, undoubt- edly, that alike of their birth and death. 4 * - The nature and magnitude of those fossils clearly show that the temperature under which they lived and flourished has been essentially altered, and that the living species, genera or analogues, of those found in high northern latitudes are now con- fined to a tropical climate. Indeed, their organization proves that they are capable of existing in no other. Hence the inference that the climate of those latitudes has been reversed; and it is con- clusive. In accounting for this, conjectures have been started, and conflicting opinions expressed; but that it may be attributed to the difference in the relative position of these parts of our Earth to the Sun from that which they formerly sustained, there appears to us little reason for doubt. The author himself, in a mote, in which we fully concur, maintains the agency of principles which, though of a different nature and unapplied by him to the solution of this question, affords, in our opinion, means by which to ac- count for any degree of temperature within the earth itself. The bases of the earth's—assuming conclusions from these principles —being metalic and inflamable, or so rapidly combining with oxygen in their pure or primitive state, under all probable atmospheric circumstances, as necessarily to induce combus- tion;–intense heat must have been generated during their rapid oxidation in the earlier state of the planet. And, until these me- talic bases become so oxydized as to render the earth—which is the result of that process—inhabitable, no organic nature could have existed, as we find it did not, until at that comparatively early period in our earth's formation. Thus the metalic bases yet un- oxidated, and now less exposed to the oxidating principle, oc- cupying the central portions of the earth, or there forming a nucleus, may still be in a state of slow combustion, generating the heat and producing the volcanic phenomena inferred from such a state of things. This, whilst it accounts for the gradual increase of temperature as we descend from the surface—definitely ascer- tained to be in the ratio of one degree for every 50 or 60 feet— clearly proves the temperature, at a distance of about 45,000 feet from the surface to be such as that all rocks known to us would be incapable of sustaining it. That centre, or nucleus, may, there- fore, present the phenomenon of the metalic bases of the earths yet unoxidized, or partially undergoing that process from the superficial means, which at times, or at places, may be presented to the exterior of the mass. There are many phenomena which might be explained by this metalic central attractive, or igneous centre; but, if accredited, the occasion might not require a further notice of the theory or only in reference to the question under con- sideration. If we admit the fact, as now maintained by eminent geologists, that the centre of the earthis a nucleus of heat diffusing itselfequally from thence to its surface, and of sufficient intensity to produce the effects attributed to it, we have a cause for the high temperature which existed during the earlier state of our earth. But whether 126 - - NOTE. E. this heat was then equal on all parts of the surface and contributed materially to the growth of animals and plants, now unknown to such parts, and whether that heat has diminished in accordance with the geological order of the superposition of rocks, it is not how necessary to discuss. Still, that the temperature must have been far greater than it now is, cannot be doubted. It would follow, as the effect of causes thus admitted, that there was a time in our earth's history at which it was incapable of Sup- porting organic life, and this we find proved by its stratification; and, in the composition of the earliest order of rocks there are, therefore, no remains of organic nature. Those rocks evince the effects of that heat which has been supposed. But on the sub- sequent formation of strata of a less igneous character and capa- ble of sustaining life, we find organism to have appeared, and under such circumstances as to have been peculiarly adapted to the state of the earth it occupied. During successive superior arrangements of strata, the degrees of heat as gradually diminish- ed, and they thus became better prepared for the support of ani- mal and vegitable life, and that, too, of a higher order of perfec- tion and capability. From these primitive formations and this early condition of our world, upward through successive superposi- tions of strata, it is found that animals and vegetables of peculiar orders successively came into being, flourished and became ex- tinct. The periods of time required for these events, it is impos- sible to estimate; but that they were indefinitely longer than that which has been imputed to the earth's existence by many or by re- corded data, is unquestionable. Myriads of years may indeed have been required for the formation of one stratum, or for the appearance and ultimate extinction of an entire race or order of existences, now only to be found deeply embedded in the interior of the earth. The first specimens of organized life, as has been intimated, are to be observed soon after the consolidation of the earth's sur- face, and subsequently to a revolution of its elements, preparatory to its becoming an inhabitable world. This, as also suggested, was during an early condition of our planet and far duwn in the order of stratification, as it now exists; and the forms and habitudes of the primitive tenants of the earth were, as should be supposed, wisely adapted to that condition. Simple in structure and cor- respondingly so in endowment, they come into being, lived out their allotted time and disappeared forever. New forms of exis- tences, more perfect in organization and more highly endowed, succeeded, and in turn, shared the same destiny. Revolution fol- lowed revolution on the earth's surface, and each dying, with each reviving, order of beings, become entombed amid the con- flicting elements. On the remains of one, flourished another and a superior class; and thus Fº throughout an indefinite pe- riod of time, nature moved onward in her works from primitive formations and early occupants of our then virgin, but now per . haps, waning planet, and upward through all the varied changes to which it has been subjected, to the present superstrata, and the present exalted occupant of earth and of time—MAN. From the peculiarities of those long lost inhabitants of earth NOTE E. • -- 127 we are enabled to draw conclusions as to their natures, their periods of time and their endowments. A key has been thus placed in our hands, by which we are permitted to open to far- distant time, and to look backward along Nature's progressive steps in bringing into existence successive ranges of beings, and by which they have been swept away. Strange, indeed, do these works appear; and among them those fossil remains, referred to in the text, are remarkable. That they should be found under a climate so unsuited, nay, destructive, to their existence, whilst it excites our surprise, proves that a great change in that climate has taken place since they flourished and disappeared. When, in the history of time that event occurred, the climate, so essential to their vigor, was in its full force, and their overthrow and entomb- ment is therefore attributable to a sudden revolution in the condi- tion of the earth's surface, though that revolution may be supposed to have resulted from the slow and gradual proximity of those polar regions to the Sun, in conformity with, at least a supposed, uniform or Óscillatory motion of the earth, which we shall here- after notice. ... • The present torrid zone does not exhibit a temperature com- parable with that which nourished the gigantic fossil ſerns and, animals of the temperate or frozen zones at the time of which we speak, nor even that of the same latitudes at the present time. The comparatively diminutive analogues of those remains, now found under the equator, are illustrative of this. . In our temper- ate zone, and whilst our coal beds were forming, the fossil crypto- gamous plants, which, in their primitive glory measured twelve inches in diameter and twenty feet in height, are now dwindled to less than one-fourth of an inch in thickness and two feet in height! Ferns, which were then from forty to sevenly feet in height, now scarcely attain to ten | And the comparison is equal- ly remarkable among the fossil animals; the species or genera of which, with those of vegetables, may have been perpetuated to the present period in the hottest regions of the earth. The char- acter and habits of some have also been changed, and but dwarf- ish analogues of some northern fossil animals, 100 feet in length, are now to be found within the equatorial regions. Remains of immense numbers of the elephant and carnivoria, capable of liv- ing only in central latitudes, are now ſound in Siberia. Indeed, the earth, in earlier periods of its history, was crowded with huge and anomalous animals, as well as with those of plants, which afforded such abundant elements for our coal formations; but few of either in their living form and character, have come down to the present period. * It is quite clear that the events spoken of as producing such re- markable phenomena in the animal and vegetable kingdom, oc- curred anterior to any records by man, and that the temperature where many of these fossiliferous remains are found, has not per- ceptibly changed for at least 2000 years, during which we are enabled to trace records upon this point. And, according to M. ARAGo, the tempterature of the earth has not altered one-fifth of a degree within that time. In reference to periods of time, to which 128 NOTE E, we have often and necessarily alluded, in order to convey a just idea of the phenomena here treated of, it may be proper to re- mark, that science cannot be made to graduate its details and data by any previously formed opinions of men; qūd, though they may seem, in some instances, to conflict with such opinions, pre- sumed to be based upon unquestionable authority, yet the question simply is—Are they true? Men may err in their opinions as to re- .# facts, their meaning, their application, or their character; but whether, abstractly, their opinion is that the world is six mil- lions or six thousands of years old, it may not necessarily affect their confidence in either natural or revealed truths. That Man, the last and most perfect of all the orders of organized beings which have tenanted earth, may be tracable only to the period last mentioned, and that a signal cataclysm has since occurred, agreeably to both accredited facts, fossil geology by no means controverts, but, on the contrarv, tends to confirm. Jndging either from matural or from recorded evidences of truth, the mind im- bibes opinions agreeably to natural or constitutional peculiarities; and it is with the faculties to perceive, to compare, and to infer, wisely conferred upon us by Supreme Intelligence, that we are to know and to *:::::: any truth. Hence, men greatly differ as to the intent and scope of language; whilst, in the perception of simple and natural truths, they generally arrive at similar results. Our own opinion is, that scriptural records of cosmical phenom- ena are not to be understood as revealing those natural truths dis- closed by science; and that, in this respect, they were not intended to limit the conclusions of men, at the present day, as to the results of natural laws. Periods of time are, therefore, reſerable to natural causes, to which men are related ; and our opinions of their duration are derived from our knowledge of those causes. All things are, and should be made to appear, consistent and in halmony with the known attributes of the Great First Cause; and whilst we maintain the undeniable truths resulting from those laws, as the immediate agents of that Power, it will not appear to be a part of our purpose or duty, here, to reconcile them with opin- ions derived from other sources. There are truths, however, connected with these conclusions, which, whilst refering to this subject, it may not be irrelevant to notice—truths, that had they been better understood, or more par. ticularly regarded, during our past history, would have reconciled much of that discrepancy of sentiment and pertinacity of preju- dice, with their attendant evils, which has too signally character- ized our Social condition :-we allude to the fixed and ascertaina- ble laws of nature. These laws being observed—and it becomes the first and essential duty of man to possess a knowledge of them —we find ourselves, with all created objects, placed in intimate relation to them, that both our happiness and existence is depend- ent upon our observânce of that relation, and that they are theim- mediate agents in all phenomena. The Author of such laws, or a Great and Final Cause, both of matter and of the principles with which it is imbued, follows this observance as a natural conse- quence, a rational induction by the mind. These truths are, \ Note E. 129 then, so far as known to us, determinate in their nature, and re- sistless in their application upon all objects and throughout all space; and their results are the manifestations of that Power deemed to be omniscient and omnipresent. They are perceived to be necessarily connected with all the varied forms and relations of matter, organized and unorganized, and under all the modified conditions of circumstances in which we find ourselves and all other objects placed. Denominating this, Providence, or the immediate influence of Supreme power, changes not the fact nor our relations; we still see the same unchangable instruments in constant force and ap- plication, and the same obvious revelations of superior wisdom and determinate power. If this state of things were to be sup- posed unequally operative, or seemingly irreconcilable, we can- not attribute the apparent discrepancies to the GAUSE of those laws, but to our own ignorance of the laws themselves; nor are we jus- tified in complaining, or wrangling among ourselves, about the fact; but our social and personal duties will be seen to grow out of that fact, and to follow uniformly as the consequence of our relations to the laws in question. Viewing the matural laws in this light, we cannot lose sight of our obligations or the nature and relations of our being, whilst it will reconcile our opinions as to the evidences of truth and of that Being whose character is in- fered from them. When these laws shall be no longer operative, then our nature and condition will be changed: of their character and effects, however, it is the business of science and the experience of life to reveal—to use and not to abuse them. Of their extend- ed application also throughout infinity of matter, or space, we have remarkable illustrations in the contents of this volume. It may be inquired how these fossil remains, so long and so deeply imbedded in the earth, became thus immured, and by what means they have been ultimately revealed. A discussion of this subject involves many interesting particulars, but we have space only to allude to the two great elementary agents employed. These were fire and water—the one in upheaving from the centre, at various periods, the regular strata of the earth, and the other in levelling the surface by abrasion, or the washing away of parts and prominences and the filling º of plains and valleys and the form- tion of strata by deposition. Nor has the former been limited to the breaking up, from time to time, of the rocky beds, and thereby dis- closing to our view the contents of the fossiliferous strata, but has itself been active in spreading over the surface immense layers of volcanic exuvia. Thus these two ever active and powerful agents have, in the process of immeasurable time, effected all those ex- traordinary changes which, as we see, have characterized the physical condition of our globe. Thus mountains and rocky sum- mits have been irregularly thrown up, and piled high above the plain, by the resistless power of the one, whilst caverns have been formed, mountain sides and plains denuded and furrowed, and val- leys made or filledup, by the ceaseless operations of the other. Each in their turn have upturned or covered forever the feeble tenants of the earth. Volcanoes, earthquakes, avalanches, and the whole } 30 NOTE E. train of phenomena resulting from the same causes have in turn, changed the form and character of our earth's surface; yet even these violent means have not been more effectual in causing these changes than the secret, silent, but constantly operative agency of like powers, which, from these circumstances, may have es- caped observation. And it should at no time be forgotten that these causes are still operating and constantly modifying in like manner the crust of the earth. Indeed, the limited period of hu- man observations compared with the ultimate effects of natural causes, has led to numerous errors of judgement in estimating the results of these two great and perpetual agents, ICeeping in view, therefore, the nature and constant operations of these causes and the comparatively brief time of any and all our examinations, we cannot fail to arrive at Satisfactory conclu- sions as to the origin and completion of the revolutions to which our world has been subjected. Hence, it will be seen, that they have ſurnished at all times, the requisite means to bury the primi- tive occupants of the surface, animal and vegitable, and by their ceaseless or accumulated energies to have upliſted and exposed to view the varied forms and structures of primeval time.— Whole races of beings will be seen, by these means, to have been imbeded at intervals during the long period of our earth's history, and many were so suddenly overtaken, as their relics show, as to exhibit even their peculiar habits in the perfect and solid forms found in the rocky strata of which they now compose a part. Ex- tensive forests, enormous palms, and whole mountains of testacea, are found composing the indurated strata of extended districts. Admitting the reasoning of Mr. Lyell and others in supposing these changes attributable to the elevation of land, yet the occur- ‘ence during the formation of the Transition and Secondary series and whilst these early inhabitants were in their glory, may not be thought adequate to these changes, or happening at the same time. We have spoken of a change in the temperature of the northern latitudes, at some period of time, in reference to geological phe- nomena, presuming that this might not be considered alone ne- cessary to account for the remarkable size and vigorous growth of the plants and animals which formerly inhabited those regions, compared with those at the present time. If it were otherwise, it is possible that a different position of our earth and planetary sys- tem in Space may have been the occasion of an increased temper- ature, derived from the influence of other suns or systems of worlds, to which our earth, in consequence of its supposed greater proximity to them, may have been indebted for the cause in ques- tion. . But we are authorized to suppose, that solar heal and the genial influence of our sum was essential to the physiology of those plants and animals; and that it was, in fine, º: cause to which such phenomena are.Teferrable. If, them, solar influence was ne- cessary to the constitution and the consequent growth of those gigantic plants and animals in those regions, we must account for a change in that influence by supposing a change in the rela- tive position of those parts of the earth to the sun. And whilst Our knowledge and experience would satisfy us that such an in- NOTENE. - i3} fluence was necessary, we are, and must ever remain, in perfect ignorance as to the nature of the influence which might have been derived from a greater proximity to other supposed sums, or indeed any other celestial bodies. Å. increase of temperature may have been acquired by the supposed passage of our system, and of course the earth, through a different part of space, by sup: posing that space to have possessed a higher temperattire than that which we now occupy; but as we are conscious of deriving no such influence from that source at the present time, or at least, no perceptible influence upon vegetative nature from neigh- boring worlds, we are warranted in believing—even if there had been merely an elevation of temperature from that cause at a pre- vious period—that the phenomena in question are attributable to other causes than that here supposed. Besides, if an elevated tem- perature were alone necessary in the case, we have, as at first supposed, a cause for it nearer at hand. This cause, it was infer- red, might appear in the phenomena of the metalic bases of the earths, and the central heat, of which we have spoken; and this theory, if admitted as at first provided, would appear amply suffi- cient for the elevated temperature required, a; for other pheno- mena involved in the explanation. To account, then, for the facts in the case, it was long since sup- posed that the axes of the earth with respect to the sun have chang- ed, and that by a constant and uniform or an oscillatory motion of the earth, an approximation and retrocession of the poles to and from the plane of its orbit have taken place. This would have presented, at some distant period, the regions alluded to, with their inhabitants, in a different position from that of the present in re- lation to the Sun, and, as a consequenee, would account for the change in the climate which has been necessarily supposed. In conformity with this theory, it has been calculated that a revolu- tion of the earth's axes would require a period of 288,000 years, and that about 144,000 years would be required to bring the poles of the earth again to the plane of its orbit. These periods of time are reconcilable with facts respecting fossil remains, if we sup- pose such a motion to have produced results which we are warrant- ed in believing might follow such a state of things; for we cannot otherwise easily estimate the period required to have converted those magnificent specimens of fossil flora of the temperate lati- tudes from the green and thriſty tide of life into immense mine- ral columns, and to have imbedded them at the depth they occupy in the geological order of arrangement. We might also find other geological phenomena to correspond with this supposition and that there would be a correspondence in effect observable in lati- tudes subjected to like positions in regard to the sun. . So far as our comparatively limited periods of observation extend, there are some singular coincidences in support of this theory, whilst there are again apparent discrepancies; yet we believe the latter may be traced, in some cases at least, to our limited comprehension of lime and the indefinitely extended and unceasing energies of natural CºlllS6S. It might be said, that the judgment of men is thus liable to numer- 11 * 132 NOTE F. ous errors in physical science; and particulars might be alluded to bearing on the present subject; we have, however, in the present case, to compare the circumstances which signalize the equitorial regions with those of other latitudes, to illustrate these facts with respect to the characteristics of plants and animals. It is certain that no other plausible cause, so far as solar phenomena are inter- ested, so well accounts for the existence of these remarkable speci- mens of vegitable and animal life within latitudes the present cli- mate of which they could not sustain, or for the existence of con- generated species in the torrid zone only. , The vegetable deposits also, required for the formation of coal beds, need not conflict with opinions here suggested, inasmuch as the extension of our views in respect to time would favor the deposits where we now find them; and so with many other geological phenomena which might be noticed, but having insensibly extended this note beyond our intention, we shall no longer detain the reader. NOTE F. CONSTELLATIONS OR ASTERISMS, (See the Plates.) These are assumed figures originally forty-eight in number, conceived and delineated in the heavens by the ancients, with- in which they classed the stars. To this number the moderms have added 48 more, making 96; so that the heavens are covered with imaginary figures. Of these, 12 are in the Zodiac, or ap- parent path of the sun, 37 on the north side and 47 on the south side. Those stars not brought into the constellations were called wnformed Stars. Most of the constellations may be seen upon a celestial globe. They were of Egyptian origin; and the charac- ters representing them are hieroglyphics and rude paintings em- blematical of the objects. The most showy is the constellation Orion, distinguished by its nebulae and the belt 4 x * in a row. Sirius is below this; above and to the right is the red star Alde- baran, with the Pleiades, or 7 stars, and to the left 2 bright stars, Castor and Pollux. - To this number of constellations have been added many more by late astronomers, one of which is Herschel’s Great Tele- scope. They are all divided into three classes, called the North- ern, Southern and Zodiacal. The stars in every constellation, in order to aid the memory, are marked, as will have been seen in the text, by the letters of the Greek and Roman alphabet. Thus the first or principle star is marked (a), the next in order, (8) the third (y), &c. hen the Greek alphabet is thus finished, the Ro- man letters are used, as a, b, c, &c., and these are again succeeded NOTE G, 133 by figures, 1,2,3, &c. The application of these letters and figures to stars referred to by the author will be therefore understood. This method, in respect to letters, was introduced in 1603, by John Bayer, and has since been followed by astronomers, with the ad- dition of figures, etc. The designs by which the constellations are recognized, represent persons distinguished in ancient my- thology, well known animals, and some imaginary and other sub- jects; but these representations are intended to imbrace within their configuration a certain number or class of stars, and it is there- fore of little importance what they are. The following are the Greek and Italic letters:– ~ * Greek Alphabet. a 3 y 6 e ſ m 0 t k A H v š o T p a s T v 4 x p (o Italic Alphabet. a b c d e f g h ’ j k l m. m. o p q r s t w v w a y 2. It is not known at what period the ancient constellations were made, as it was prior to any authentic record. Homer and Hesiod speak of Bootes and the Bear, and Orion, Articusand the Pleiades are mentioned in the books of Job and Amos. º, It should be observed that, although the signs in the Zodiac served the ancients, when they formed them, in distinguishing the seasons of the year, etc.; yet, at the present day, owing to the re- trograde motion of the equinoctial points, these constellations have advanced more than a whole sign. Thus it will be seen that the point or constellation Aries is some three or ſour degrees within the constellation Taurus, or that the coincident points of Aries and the vernal equinox are advanced some 34 degrees. So that these signs, being imaginary and serving only to define the course of the sun in the ecliptic, should be distinguished from the con- Stellations now designating single stars, or groups of stars. NOTE G. NEBULIE, Wº: Thus are denominated the bright, white and hazy clouds, seen by the naked eye and commonly called the Milky Way, and as perceived by means of instruments pervading the whole heavens. Nebulae are seen to be the principal subject of discussion in this work. They develope, on examination with powerful telescopes, extraordinary facts in regard to the immensity of creation and the formation of worlds. The first discovered was that mentioned under “Trapezium” in Orion; and though as- tronomers have added many others, yet it is to Dr. Herschel --- 134 NOTE G. that we are indebted for the discovery of an almost countless number; thereby greatly enlarging our ideas of the infinity of space, and of the varied phenomena of these newly discovered and immense worlds; as well also as of the power of “Him who made them such.” Herschel divided the nebulae under four heads—those having no appearance of stars, planetary nebulae, stella nebulae, and ne- bulous stars. The nature of the truths revealed by a careful examination of the nebulae will not be doubted after a perusal of the present vol- ume, nor will the reader fail to be impressed with emotions of ad- miration and astonishment at the results. - It is perceived that in proportion as the stars recede from our great cluster, or the milky way, either north or south, they are less and less numerous, so that there is an apparent, and no doubt a real and great vacancy between those stars composing our firma- ment or cluster and others far removed in space. The telescope discloses the fact that our milky way, and also other firmaments or nebulae thus far removed, are immense clusters of worlds, “scatter- ed,” as Herschel says, “by millions, like glittering duston the black ground of the heavens!” We have but to conceive that these innu- merablesparkling bodies are suns alike, or larger than our own, hav- ing, severally, their planetary systems revolving around them in the most perfect harmony, and each so distant as to require three years for the light of one to reach the other, to realize the nature of our subject, and yet this is the result of philosophic investigations founded on determined data. Still, even this is but the threshhold to that subject, inasmuch as the other vast and innumerable nebu- lac, discoverable or resolvable by the telescope, the light of which, according to Dr. Herschel, must have been two millions of years in reaching the earth, are yet other firmaments of worlds, within the reach of human observation, existing and moving under like circumstances. But, beyond the power of human sight, how much soever it may be aided by human contrivance, what are we to im- agine?—Truly, worlds beyond worlds and firmaments upon firma- ments in infinite extent Immense as are the bodies of our firmament and great as are their distances ſrom us or from one another, yet the whole, when viewed from other nebulae or firmaments of worlds, are seen only as small indistinct clouds! These again, in turn, are viewed by others still farther distant in space, as objects of the same apparent- ly insignificant character, and so on throughout infinity. R. We have still farther to stretch the mind and conceive that each of these firmaments of countless worlds are yet but clusters, and that each of these, and perhaps a vast many more joined in the same grand system, are themselves, moving around some infinitely greater or more distant central firmament, and it may be that again around still another, — all revolving, like our own little patch of worlds, around our own small sun-and thus the mind is at once lost in the vastness of this subject. Of our own nebulous firmament, within which is our sun and system, the reader will have learned much in the course of this NOTE G, 135 work, as well also as of those nebulae which, by means of instru- ments, have been resolved into stars. And he will have particu- larly noticed, it is thought, the extraordinary fact upon which the author has touched—the breaking up of our milky way—and, as the result, he will be led to reflect no doubt irresistibly, that such a phenominon will involve, if its effects are not already manifest, our solar system and our little earth in the consequences. But, in reference to the irresolvable nebulous matter, discovered by Her- schel and others, and of the important conclusions to which it gives rise, fºre is opened a wide field for speculation. If, in- deed, as is supposed by Herschel, there are numerous nebulae that have not in fact taken on the character of stars, but which yet remain a phosphorescent, or self-luminous, matter diffused through space in the forms of clouds, and subject to the universal laws of unorganised matter, it will not be denied, from the peculiarities which he has noticed, both in their nature and motions, that they afford all the requisite elements for the creation and physical en- dowment of future worlds. Nor is it less conclusive that their phenomina present a clue to the great processes and the operative agents of nature which have been heretofore employed, in con- formity with primary and established laws of matter, in bringing all worlds into existence. Here the mind will find ample room and strong incentives for conjecture and for the application of scientific laws. Thus based on the observations which have been made by Herschel, the laws developed by Newton, and so ably ap- plied and established by La Place, there are certainly strong rea- sons for admitting the theory here suggested. We are justified, in reasoning from analogy on this subject, to resume at least, that each nebula, or cluster, bears the same re- ation to other nebulae or clusters and a centre, that our planets do to one another and to the sun, whilst each individual is itself the centre of a system, like that of our own. Thus there would be an infinite number of systems in each group, all complete and revol- ving in harmony among themselves, whilst there would also be one grand or universal revolution of the whole around some im- measurably distant, magnificent, and all-sustaining centre - The existence and application of the inherent principles of matter composing our earth and extending to other planets of our system—such as the great laws of gravitation, inertia, &c., and by which all are maintained and regulated, are traced to the fixed stars. From thence it is both matural and necessary to extend and apply them to still more distant and greater objects, such as the groups and firmaments of stars disclosed among the nebulae of space. The establishment of these universal truths enables us to infer, as a consequence, a uniformly balanced and rotatory mo- tion prevailing among all systems of worlds, large and Small, near or distant; thus securing that equilibrium, that motion, and that harmony throughout creation, which, so far as human observa- tions extend, are uniformly observed. And it is in accordance with these principles and facts that the Pºiº of all nebulae appear, and to which they are all referable. Hence Systems, groups of systems and firmaments of worlds, Systems and groups, 136 NOTE II. º all joined and rolled onward in one vast and wonderful whole. From such data, and as the results of his observations, La Place, the most eminent mathematician of any age, supposes that our sun and its planetary system—and accordingly all other systems, as are inferred—was primarily a portion of the irresolvable nebulous matter, or phosphorescent vapour before refered too, the ultimate condensation of which into a nucleus, generated the heat, the ro- tatory motion and all the phenomina of A SUN. That, as this heat gradually subsided, the atmosphere of the sun as gºidually con- tracted; so that portions of the nebulous matter not attracted to- wards its centre in this subsidation and ſormation of its atmos- phere were, from their centrifugal motion, thereby detatched and left in revolving annuli or rings. These again, he supposes, were gradually condensed into solid bodies which now appear as our planets or their satellites, and thus, from well known laws of matter and oſmotion, they would naturally present all the pheno- mena which characterizes our solar system. NOTE H. FIXED STARS, Fixed stars are so called in reference to their appearance as respects us and other planetary bodies; but the greai mass of all those discoverable are of the same character, and they all have motions, perhaps orbitual, like the planets. Motion is indeed universal; it is the evidenee every where of existence, and the cause of all phenomena. Although we may have inferred this from our own limited comprehension of things here, yet the tele- scope has revealed extraordinary facts as to the application of those general and elementary laws of matter and of existences throughout celestial space. Much of that which is known res- pecting both the nature and revolutions of stars, or the firmaments of worlds that thus fill all space with life and motion, is noticed in this work, but many of their phenomena are not familiar to all. There is, strictly, a great variety in the relative magnitude of stars, indeed almost as great as is their number; and, although they have been classified into degrees of size, extending to the 12th order of distances, as regards space and as seen by the naked eye, or by the aid of instruments still further; yet Leland in his catalogue of 600 of the 1st magnitude, reckoned 126 of intermediate magni- tudes. These are not magnified by the telescope as are the planets, but appear with an increased lustre which, with some of those of the first order, as seen in Herschel's largest telescope, was too great to be endured by the eye. Their twinkling is attributed to the pausity of their light in passing to us. They appear some- what larger to the naked eye than when seen through a tube or NOTE H. *. 137 instrument and unaided by atmospheric light. We do not see with the naked eye in either hemisphere more than 1000 of these stars, though they appear much more numerous, owing to the confused manner in which they are viewed. The nnmber, as seen through a telescope, is infinite. The nearest and brightest is the star Sirius, estimated to be 32 billions of miles distant from the earth; so that it would require seven millions of years for a cannon ball to reach it, constantly flying with a rapidity equal to that which it would have on leaving the cannon. To the inhabi- tants of Sirius our'sun appears as a star, and the planetary system revolving around it, of j. the Earth is one, is unseen, as are those of Sirius by us. All the fixed stars are supposed to be cen- tres, or suns, of complete planetary systems. They are classified under six different magnitudes, according to their apparent size to the naked eye; smaller ones are called telescopic stars, being seen alone by the aid of an instrument; and their relative magnitudes are thus, as before intimated, greatly increased. The first catalogue of the stars was made by Hipparchus from his own and the observations of the ancients, and contained 1022; to this number successive astronomers have continued to make additions. Leland completcd a list and determined the places of 50,000 stars, from the pole to two or three degrees below the tropic of Capricorn; and, in a space of only 10 by 23 degrees, j computed 258,000! Yet still his observations could have added to this number indefinitely. It is not satisfactorily known whether the variety in their appearances is owing to their real magnitude or to their distances, though it is probably attributable to both of these causes. But, with respect to their locality, astronomers have defined their places with as much precision as are those of cities and towns upon the earth. Stars which before appeared single have also been discovered to be double, triple, quadruple, and multuple. Herschel completed a list of more than five hun- dred of these stars, and Professor Struve has added to the number near 3000. The distance of the stars may be conceived by the fact, that the moon actually eclipses 2000 of them at once, that some of the brightest do not subtend an angle of 1", and that for the sun to appear less than a second it should be removed 1900 times further distant from us. It is conjectured that their dis- tances are nearly inversely as their apparent magnitudes. Again, although we, in our annual orbit around the Sun, are 190 millions of miles nearer some of the stars at one time of the year than at another, yet even this immense distance makes not the least perceptible difference in their appearance to us, with the aid even of the most powerful glasses, so trifling is it when compared with that of the nearest star; and, though light moves at the rate ºf 12 millions of miles in a minute, or 192,900 miles in a second of time, yet, according to correct data, more than a year is required for the light from the nearest stars to reach our earth, and from the telescopic stars even hundreds of years! so that the light by which they are visible to us is many and even hundreds of years old ! Some faint idea may, perhaps, be gleaned from the following analagous representation. Suppose the earth a globe 1 foot in 138 Not E H. diameter, the sun's distance would then be about 2 miles, its dia- meter about 100 feet, or twice the size of the largest dome of the Capitol at Washington, and the moon would be 30 feet from us, with a diameter of 3 inches. Jupiter would be 10 miles, and Uranus 40 miles distant, and the nearest of the fixed stars might be the distance of the moon, or 240,000 miles | Our highest moun- tains would then be one 80th part of an inch, and therefore barely perceptible to the naked eye; and man, with all else indeed on the earth, would be as the finest bloom on a plum, or the thin dust upon a globe. - We might, again, for lllustration, go down to the infinitesimal and invisible objects of the microscopic world, and to aid the mind, draw comparisons from the animalculae and infusoria, millions of which float in a drop of water, or whose attenuated structures compose the solid limestone masses of the mightiest mountains. Herschel concluded that the distance of even the nearest star cannot be so small as 48,000,000,000 radi of the earth, or 192,000,000,000 miles Dr. Walaston, by a comparison of the light of Sirius with that of the Sun, ascertained that when the light from either reached the Earth, that of the latter is 20 billions more intense than the former; and that for the Sun to appear no brighter than Sirius it should be removed 141,400 times further distant than it now is. He calculated the distance of Sirius from the Sun to be such that its own light must be equal to fourteen SºnS / Although we might despair of determining satisfactorily the distances of the stars by their parallaxes or otherwise, except those perhaps of the nearest, yet ARAGO, the present distinguished French philosopher and astronomer, has suggested a method of fixing that of the binary or triple stars, which should be noticed. A binary star, for example, disclosing to the observer nearly its edge, would, during half of its revolution, recede from him, and during the other half would continually approach towards him. Now, if the light of that star were thirty days in travelling from the nearest part of its orbit to our earth, it would-be more than that time in passing from its most distant part; the difference, therefore, between the apparent and the calculated time, from the nearest and the most distant points of its orbit, even though it were but a ſew seconds, would furnish data by which to determine its dis. tance. Thus, it will be perceived, that the semi-revolutions of the star differ by the double of the time required for the light to pass across its orbit, and half of that difference in seconds, multiplied by the number of miles which light travels in a second—say 200,000—will give to the observer the diameter of the orbit, and from this he may easily calculate the distance ſrom the earth. In view of this M. Arago well observes: “The day in which the distance of a double star is determined, will be the day in which it may be weighed, and in which we shall know how many mil- lions of times it contains more matter than our globe. We shall then penetrate into its internal constitution, though it may be removed from us more than 120,000,000,000,000 of leagues " • . - NoTE 1. 139 “How distant some of the nocturnal suns | So distant, says the sage, “twere lot absurd To doubt that beams set out at Nature’s birth Had yet arrived at this so foreign world, Though nothing half so rapid as their flight !” The different colors of ſhe stars, as alluded to by the author, is likewise a remarkable phenomenon, as well also as the changes in their situation, 50 of which was discovered by Herschel among the double stars, In one instance of these combinations—in the Lion—the revolution of stars around each other requires a pe- riod of no less than 1200 years. In the double star Castor, also, the revolution of one around the other during 50 years has had a rota- tory motion of one degree a year, without any alteration of the in- terval of 5" between them. Many of the double stars are like- wise observed to have different colors, as, for example, that of Bootes, one of which is a light red, whilst that of the other is a fine blue; and the period of the latter's revolution was also discow- ered to be 1681 years . That of Herculis, being double, presents the larger of the two of a beautiful blueish-white, while the smaller is a rich ash-color. The smaller star of Serpentis makes a revo- lution around the larger in a period of 375 years; and the same in the double star Virginis in 708 years l Nor are the strange changes which these and numerous other stars have undergone in their color, brightness, position, and other circumstances, less worthy of remark; but a note is quite too limited to give even a notice of them. The more curious reader is, therefore, referred to Herschel's and other late works on the subject. NOTE [. GRAVITY. Of all the principles in nature, no one is so general in its ap- lication, no one so important or So grand in its operation as this. hich way soever the eye is directed, there it is seen. Where- ever thought penetrates, there is it present. Here, there, every where, it is ever active, ever powerful. Upon the minute grain that here, with its neighboring millions, just received the impress of our footstep, and there upon yonder worlds “that wheel their ample range through depths of ether,” it is alike active, alike essential. Not a moment witnesses its inaction; not a particle escapes its energies. With the thought that now perceived it, and the Eternal Beginning that gave it power, it was the same. Comets “coasting unnumbered worlds of more than solar glory,” and infusoria, floating unseen in a water-drop, are bound alike irresistibly by its command. Not the Earth—not the Sun—not all the planetary system—nor yet the whole firmament, has fixed its bounds; Infinity alone hath appointed it limits. ſº 12 140 NOTE I, In looking into nature—whether upon our planet, or amid the countless worlds that throng the eternity of space—we cannot fail to be impressed with the ceaseless power of this all-important agent. Whilst it confines the little things of earth to its surface, it is equally operative in restraining the heavenly bodies. What- ever the first principles of this great cause may be, and by what- ever name it may be known, it is every where similar in effect, whether cohesive, gravitative, electrical, or chemical. It per- vades all matter; all objects are subject to its control, affecting the impalpable and ponderous in proportion to their substance. It " may be that this property of matter, in modified conditions, has received different names —its peculiarities we know, and their analogies are observed. May it not be the inherent principle of election that manifests itself among the elements of matter, and in the incipient stages of organization 7 May not the delicate chrys- tal exhibit its properties slowly developing themselves in the nice and beautiful arrangement of amorphous atoms? Is it not the germ of motion, the beginning of order, the principle of organic structure, and the element in the atomic theory 3 From these small and primary manifestations of power, may it not be observ- ed in the various and modified exhibitions of elemental life and motion ? It may take various forms or modes of action, as the nature and combinations of matter vary, or the circum- stances under which it acts 7 Will not the metalic bases of the earths, when their peculiar properties are known, as the central source of terrestrial heat and power, as heretofore mentioned, ex- plain many phenomena as to this mysterious agent, as well as those of magnetism, etc.? This property of matter Newton and others, attributed to effluvia emitted from bodies, etc.; but this has been controverted, and the analogy in the general laws of attraction, whether cohesive, capillary, chemical, electrical, magmetic, or the peculiar “affinities” of matter, in masses or molecules-all oper- ating with similar forces and laws;·-has induced the opinion that they are identical with caloric. The identity is, indeed, clearly illustrated in some, at least, of the various forms of attraction. It has been Supposed that space is filled with an etherial elastic fluid, whatever its name may be, which, operating in right lines, presses bodies together, as on one side in space it acts infinitely, whilst on the side attracted, or between bodies, it acts finiſely. As attraction is always in proportion to the quantity of matter, it de- creases by the same law as surfaces increase, or according to the squares of the distances of the bodies from each other. It was as- certained by Kepler and confirmed by Newton that, from the uni- ted forces of attraction and rectilinear motion, the squares of the periodical times or revolutions of the planets are as the cubes of their distances, and that the distance of the earth from the sun and the times of the planetary revolutions being known, their distances may be determined by the rule of proportion. When, however, we perceive its great functions, its potent and extended influence, we wonder at the results. It gave solidity to all the varied parts of earth, formed them into a globe, holds all to its centre, with the innumerable things upon its surface;—gives to the whole, motion Note j. 141 and restrains that motion within its orbitual bounds. Since Man came into being, its power has been felt and acknowledged; but it was not until since Kepler and Newton arose that we have dared to conjecture its vast powers. Now, its all-pervading influences are seen. We now perceive it active in forming the countless multitudes of worlds throughout space, so admirably spoken of by the author. This great principle once established by Newton, the mind broke through the narrow confines of its perceptions and flew to “world beyond world,” and there beheld it in full and con- stant force. - Inertia, as related to this power in moving bodies, would seem to be its negative. It is that property of matter by which bodies are disposed to remain as they may be, either quiescent or in motion. When in the former state, they are subject to the law of gravitation, which is paramount; but whilst in motion, they are under the influence also of another law or force proportionably to the extent of that ſorce, or the laws which gave it; their obedience to those laws cannot therefore be denominated an independent positive or elementary law, any more than cold, which is the ne- gative of heat, is a law. The obedience of matter, when at rest to the law of gravitation is obvious, but its motions, or obedience to other laws, when the law of gravitation is overcome by them, is not a Jaw, for the law of motion is then paramount. Two laws cannot be paramount at the same time. The projectile force and the restraining or gravitating force act in contrariety, the latter being positive and acting upon known principles in pro. portion to the amount of matter, and the former in obedience to the laws which gave it, which are also positive; the obedience of matter to either, therefore, implies no positive law, but the absence of one and the prevalence or paramount force of another. We make these remarks as explanatory of the laws of gravity, and in accordance with our ideas of vis-inertia, which may not be under- stood, by some as explained in the books. The effects of gravitation upon the earth must be familiar to all in the phenomena of falling bodies. Thus constantly acting on all bodies near the earth, it prevents them from being easily re- moved. Bodies thrown in an oblique direction are attracted in a curvilinear line until they strike the earth. If, however, a body were to be projected horizontally from a great height, with such force as to move half round the earth in the time it would require to fall from thence to the centre of the earth, and it continued to move with the same velocity, it would revolve around the earth forever. These and other particulars of gravitation applied to celestial bodies, are seen to reveal the great principles by which they are governed, and which have led to the explanation of celes- tial phenomena previously unknown. The same principles also applied to nebulae, as suggested by our author, unfold the wonder- ful truths to which he refers. - 142 NOTE. J. NOTE. J. BlogRAPHICAL SKETCHES. ARAGo, Dominique FRANcois, born in Perpignon, France, in 1786, and now one of the most eminent scientific men in all Eu rope. The particulars of his philosophic inquiries are possessed of much interest; and he still continues to contribute more to the advancement of Science than perhaps any other philosopher of the day. As an active and distinguished member of the French Academy of Science, his frequent papers read, before that body on various scientific subjects, are looked for with lively interest. AGGRIPPA, HENRY Cornelius, born at Cologne, 1486. This is probably the individual alluded to by the author. He was a man of learning, but nevertheless one of great eccentricity. He was Secretary to Maximillian, long attached to his army, and subse- quently knighted. He made great pretensions to magic, and though well versed in the science of the day, he opposed and ridi- culed the whole of it. As an occult philosopher, he attracted great attention ; but failing at length to satisſy many distinguished personages of the power of his magical performances, or the truth of his dreamy philosophy, he ultimately died, poor and neglected, at Grenoble in 1539. BUFFon, GEORGE LOUIS LECLERCE, one of the most celebrated Natural Philosophers of the 18th century, was born in Burgundy, in 1733. He travelled much, and was a close observer of naturai phenomena. Animated by an undefinable love of learning, he acquired a mass of information, which greatly distinguished him when applied to a definite object, and particularly that of Natural History. He was associated with D’Auberton in bringing forth a splendid work on this latter subject, after from ten to fifteen years labor. Subsequently to his death, appeared his Epochs of Nature, to which reference is made in this volume, together with other works, all of which, whatever his theories were, exhi- bit great research and the most splendid powers of thought. Al- though fifty years had been devoted to these elaborate works, yet even these were but a part of the great plans he had sketched, some of which have been filled up and continued by others. Although his theory of the Earth possessed great merit, yet it is not admit- ted by philosophers. Buffon is admitted to have been unrivalled for his elevated ideas, dignified expression of thonght, and lofty and harmonious style, and not less, indeed, for his originality of Views. He was made a Count, and a statue was erected to him during his life-time. He died in Paris in 1788, at the age of 81 }. and his son perished by the Guillotine during the Revo- ution. GALILEO. The name of this Natural Philosopher and Astrono, mer is well known. He was born in 1654, at Pisa. He had supe- NOTE. J. 143 rior advantages which he turned to the best account. He made many discoveries in Astronomy, and was greatly honored, being well known as the discoverer of the telescope. He had great dif: ficulties with the philosophers of his time, and still more with the Priests, who compelled him to renounce his opinions, founded on his astronomical observations, and by whom he was disgracefully pººl. He died in banishment in 1642—the year Newton WàS OOTI). HERSCHEL, SIR JOHN, Son of a musician, born in Hanover, in 1738. He studied music under his father, and afterwards taught it in England to the military. His leisure hours were how- ever devoted to Mathematics and Astronomy. Being dissatisfied with the telescopes of the day, he made a very superior one him- self, after much labor. This encouraged him to construct still larger ones, though at great pains and expense in perfecting them. After this, he partially withdrew from his profession of music, and pursued astronomical observations. Eighteen months afterwards, he discovered a new planet, which he named “Georgium Sidus.” George the Third settled a salary upon him, and he continued to apply himself closely to his favorite subject. Having at length completed his enormous telescope of 40 feet and 43 feet diameter, he discovered the moons and rings of his newly- discovered planet, together with several volcanoes in our moon. He was constantly engaged in determining the orbits and motions of the planets and stars. In 1802 he presented a catalogue of 5000 nebulae, nebulous stars, etc., which he had discovered. He re- ceived numerous honors, and at length died in 1822, and was buried at Upton, England. HERSCHEL, JoHN W. F. This is the Astronomer to whom the author so frequently refers. With his discoveries and talents the reader will have become acquainted in the course of this work. He has done much for the science; and it was expected that he would have communicated some new and important particulars on his return from the Cape of Good Hope, as mentioned by the author; but although he returned some two years since, he has not yet published the information anticipated. He is now enga- gedin scientific pursuits, and particularly those relating to electro- galvanism, in which he has made some discoveries. Since his return he has been made President of the Royal Philosophical Society, and is now greatly respected for his talents: HippARGHUs, a mathematician and astronomer of Birthynia, who died 125 years before the Christian era. He made calcula- tions of eclipses for 600 years, and was the first who reduced as tronomy to a science. HERSCHEL, Miss CATHERINE, noticed in this work, was the sister of the elder Sir John; and besides her great assistance to her bro- her, not only in his observations, but in the construction of his ºn $ wº 144 NOTE. J. - great telescope—she having polished the great S eculum, it is said, with her own hands-discovered, herself, several comets. HALLEY, EDwARD, born in London, in 1556, and graduated at Queen's College in his 17th year. Before he was 19 he supplied a defect in the Keplerian theory of planetary motion. He subse: quently established the motion of the Sun on its own axis, and remained at St. Helena two years making observations. His theory of the variations of the magnetic compass is well known; though not now satisfactory to scientific men. The details of Kepier's laws of the planets engaged much of his attention. He received many honors and appointments, and afterwards Was ap: pointed Astronomer Royal, at Greenwich, where he contributed much to Astronomy. He died in 1742, and was said to have been the greatest astronomer of England. KEPLER, JoHN, a great mathematician and astronómer, Was born in 1771, in Wurtemburg. Though descended from a noble family, he was poor; he succeeded, however, in entering a Uni- versity, and in distinguishing himself in his studies. Pursuing his favorite science, he was afterwards appointed a Professor of Mathematics, etc. Becoming acquainted with Tycho de Brahe, his prepossessions were greatly increased in favor of astronomy, and he devoted himself to the preparation of the famous Rodol- phine tables, printed in 1626. Various vicissitudes, however, ſol- lowed : but he was finally appointed Imperial Mathematician. The laws of the planets deduced by him, and called the laws of Kepler, are well known in Astronomy. On these were founded Newton's subsequent discoveries, as well as the whole modern theory of planetary laws. It would be impossible to notice at length the résults of Kepler's labors: he died in 1630, at Ratisbon, where a monument was erected to his memory in 1808. LAPLACE, PIERRE SIMON MARQUIs DE, a most distinguished Mathematician and Astronomer, was born in Normandy, 1749. He was the son of a farmer; and, on going to Paris, was soon known for his knowledge of analysis and the highest branches of Geometry. Being chosen a member of the Academy of Sciences, he was also made a member of the Bureau des Longitude. In I796 appeared his famous work “Ea:position du System du Monde?” he was afterwards made Minister of the Interior by the First Consul, Chancellor of the Senate and Member of the Légion of Honor. . In 1799-1805 appeared his “Traite de Mécanique Celeste,” with Several other works of great merit. In 1814 he voted for the abdication of Napoleon, and was subsequently crea- ted peer, with the title of marquis, by the king. His Mecanique Celeste was translated by Doctor Bowditch, of Salem, Mass., with additions, etc., which is one of the ablest efforts of American talent; the book is likewise distinguished as a specimen of Amer- ican typography. , Laplace died March 5, 1827, regarded as the most distinguished mathematician of the age. GLOSS ARY, . 145 LAGRANGE, Joseph LOUIs, not less celebrated as a Mathemati- cian than Laplace, and by many considered his superior, was born in 1736. His natural taste early displayed itself; and, at 18, he made many discoveries; among which was that of the solution of Euler's problem on the isoperimetrical figures and the theory of the least action. At 19, he was made Professor at the Artillery School of Turin, where he was distinguished as the founder and principal of a scientific association, which attracted great attention. He afterwards gained a notable prize at the Academy of Sciences, (where he was Chairman of the Bureau, des Longitºnde,) in treating the subject of the planetary system, and was invited to Berlin by the great Frederic; after whose death he returned to Paris, where, in 1787, he was received with great honors. His health subsequently declined, with his taste for his favorite science: still, he was honored by numerous appointments, literary and civil, after which his taste for mathematics returned, and he stood first in France and elsewhere as a mathematician. Napoleon, with all other eminent men, showed him the greatest respect; but, with all his honors, he was still modest and retiring, applying himself to his studies as intently as ever, which probably hastened his death in 1813, though at an advanced age. His greatest work was Mecanique Amalitique: he wrote many others, however, of little less importance. - NEwToN, SIR ISAAC, was born in Lincolnshire, England, in 1642. He early displayed a philosophic taste, and afterwards, at College, greatly dislinguished himself in mathematical knowledge, where he laid the foundation of his fame. Before 23 years of age he began to apply the principles of gravity, which he discovered, to the phenomena of the celestial bodies, and also to develope the laws of light. Pursuing these subjects for many years with dili- gence and enthusiasm, aided by a natural genius of almost une- qualed powers, he accomplished for Astronomy and general science that which has immortalized his name, and conferred on É. the most exalted blessings. He died in 1726-7, and was uried in Westminster Abbey. STRUve, the distinguished astronomer referred to in the text, is a German, of great energy and perseverance in the pursuit of his ſavorite studies. His observations are evidently conducted with skill and the most adequate means. We have not at this moment the particulars of his life at hand; but he is now prosecuting his researches at Altona, near Hamburg, with undiminished ardor and success, . Tycho BRAHE, a celebrated Astronomer, born in 1546. He had an early inclination for mathematics; and when but 14 years of age, he commenced the study from the effect of an eclipse upon his mind. He erected the Observatory alluded to by the author. He first asserted the principle that the earth remains fixed, and that the Sun moves around it, which was disproved by Copernicus, He was much honored, and died in 1681. - G L O S S A. R.Y. A. Aspect, situation of the stars with respect to one another, or the lanets. - A} action, that inherent principle of matter by which bodies mu- tually tend toward each other, or to the centre of the earth. Astronomy, from Aster, a Star, and Nomes, a law, the science which teaches the motion, magnitude, and distances of the heavenly bodies: - Annulus, a ring—Annuli, rings—Annular, ring-like. Approacimate, next, near, approaching. Approacimation, being nearer, approaching to place or quantity. Andromeda, a female, a northern constellation, containing 66 stars. Avis, (Axes, plural) a line, real or imaginary, passing through the centre of a body revolving upon it. Achromatic, colorless, remedying aberations of color. Arcturus, a bright star of the 1st magnitude in the constellation Bootes. Amºnus Magnus, great year. Aries, the Ram, one of the constellations of the zodiac, containing 66 stars, the point of intersection of the Ecliptic. Accelerated, ratio. (See laws of velocities.) Aldebaram, a red Star of the 1st magnitude, and the Bull's eye, in the sign Taurus. Arc, part of a circle or curve, the sky. Abrading, wasting by degrees, rubbing off, or washing away. Aggregation, collection, gathered from various sources into a mass. Adolescence, flower, or prime of youth. Alkali, an earthly salt, a substance combined with acids forming salts, turning vegetable blues to green, etc. Amorphows, without definite form, irregularly mixed. Alioth, a star of the 3d magnitude in Ursae Major. Apocryphal, of uncertain authority, not canonical. Analyst, one who resolves things or principles into their compo- nent parts. Asteriods, the four planets lately discovered moving in eccentric circles between the orbits of Mars and Jupiter. Avalanche, the falling of a large body of earth or snow from a mountain, a “slide” of either from an inclined plane into a valley, etc. - *. 148 * * GLOSSARY. Algol, a star in the constellation Perseus. Ahtinous, the Youth, a part of the constellation Aquila. Arcticus, a star of the first magnitude in the Great Bear. Altair, a star of the first magnitude in Aquila. Analogue, one of a kind, a plant or animal of the same species or genera. - Anomalous, irregular, strange, out of rule. Atoms, atomic weights, original quantities, forms or proportions in which the elements or particles of matter combine, constitu- ting the subject of the atomic theory. Acid, a substance, or fluid, forming saline compounds with alka- lies, generally containing oxygen, and turning vegitable blues to red. - Aquila, the Eagle, a northern constellation with 71 stars. Arago, R - 3:...}see Note J. B. Base, foundation, pedestal, original substance in a chemical com- pound. * Binary, double, consisting of two. Betelguez, a star in Orion. Bootes, a northern constellation containing 54 stars. Bellatria, a star in Orion. Buffon, see note J. C. Canis Major, the Great Dog, a southern constellation in which is Sirius, the brightest fixed star; it has 31 stars. Come, a body with a circular base declining to a point, like a sugar loaf. Comical, form of a cone. - Cancer, the Crab, a constellation of the Zodiac; the sun has its greatest declination on entering this sign; it contains 83 stars. Convergent, tending to a point from different directions. Collocation, placing, fixing, state of being placed. Correllative, having a reciprocal relation. Cognate, kindred, alike, born together. Cosmogony, creation, theory of the formation of worlds. Complex, compound of many parts, difficult or entangled. Cosmical, relating to the formation, or system, of the world, rising or setting with the sun. Cortage, train of attendants. cºration, form of various parts adapted to each other, out- €S. * - Co-ordinates, holding the same rank, time or place. Cycle, periodic space of time, or quantity of distance, a period in %; the same revolution begins again. The Lunar cycle is a period of 19 years, in which the new and full moons return on the same days as they did 19 years previous. This period GLOSSARY. 149. is called “the Golden Number.” The Sun's cycle is a period of 28 years, in which the days of the month return again to the same days of the week. * Chrysalis, first change of an insect, passing from the caterpillar or the reptile form into a moth or butterfly. Congeries, a collection of several small bodies in one mass. Casiopeia, lady in a chair, a northern constellation containing 55 StarS. - Ceres, a primary planet (one of the Asteriods) between the orbits of Mars and Jupiter, discovered in 1801, by M. Piazza. Coalesce, to unite, to grow together. Conjunction, having the same degree of longitude. Chaotic, confused, irregular mixture of elements. Charting, delineating, mapping. Centrifugal, flying from the centre, disposition to fly off. Centripetal, attracting, tending to the centre, (contrary to the above.) These two powers acting upon the planets, cause them to move in orbits. Constituents, parts composing and essential to the whole. Capricormats, the Goat, a sign in the Zodiac. Castor, one of the Twins, a star of the 1st magnitude in Gemini. Coroma, Borealis and Australis, the crowns, also stars in northern and southern constellations. Constellation, or Asterism, certain figures delineated in the hea- vens by the ancients, and also by the moderms, within which the principal stars are included for the purpose of better finding and describing them. (See note F.) - Circumpolar, signifying such stars, as being near the pole, move around it. They set below the horizon in our latitude. Comets, celestial bodies appearing at uncertain periods, with mo- tions resembling those of the planets. Capella, a star of the 1st magnitude in Auriga. - Clusters of stars, a collection or aggregation of stars which will be seen frequently referred to in this work. (Herschel regarded them as the most grand and beautiful arrangement of the stellar universe. By turning to several of the plates they will present a mottled appearance, nearly round and compressed. They clearly exhibit a central attractive power, and beautifully illus- trate the theory alluded to by our author.) Centauri, the Centaur, (half man and half beast,) a southern con- stellation. Coma Berenices, a nothern constellation composed by Hevelius out of unformed stars between the Lion’s tail and Bootes. Cephei, a star in the constellation Cepheus. Crateriform, in the form of craters, gullies, or fisures. Cryptogamous, concealed, a class in Botany with stamens and pis- tils concealed. Cataclysm, a deluge, or inundation. - Carnivora, flesh-eater, animals which feed on flesh, Congenerated, kindred, similar in nature, same genera, species, or sub-species. * -150 GLOSSARY, ' D. Dºſtagration, consuming by fire. Diagram, figure or representation used for illustration. Deflect, to turn aside, to deviate. Detritus, (debris,) sand or dirt washed tegrated rocks abraded, sediment. " . Dynamics, Momenta—treating of bodies in motion, as of revolving celestial bodies. Dynamical, relating to dynamics. Descry, to spy out, detect, discern. Disc, a circular surface appearing plain, the face of a body as it appears to us. Dogmalize, assuming to be undeniable, beyond other authority. Degree, 30th part of a sign, definite space in the heavens or on the earth, and a 90th part from the equator to the pole. Doradws, a southern constellation. Dorpat or Dorpt, a town of Riga, Russia, where a University lºoservatory were established and liberally endowed in 1802. away, or remains of disin- E. Engirdling (engirt), Surrounding, encircling. Epoch, particular period of time, period from one date to another. Elongated, lengthened out, protracted in time or distance. Evolution, unfolding, or unrolling of any thing. Equilibrium, equipoise, or equality of weight, motion, or sub- Stance. - Enigmatical, obscure, doubtſul. Ecliptic, the apparent orbit of the earth in its revolution round the sun, inclined to the equator on an angle of 23 deg. 28 min. Equally, uniformly, evenly. - Experimental Physics, laws of matter demonstrated by experiment. Eliptical, of an oval form. Eccentric, irregular, deviating from the centre, distant from the foci of an eliptical orbit. - Evenescent, vanishing, volatile, º: Efflorescence, the formation of powder or flowers, evolution of new things or principles. - Earth, our planet, third in order from the sun, its orbit lying be- tween Venus and Mars, with one satellite. Elabora!ed, produced with labor, improved by successive opera- tions. Blipticily, likeness to an oval. - Equinoctial, or Celestial Equator, the imaginary circle in the heavens described by the sun in its daily revolution at the time of the equinoxes, or its apparent passage over the line, when days and nights are equal all over the earth; the centre of the Ecliptic. Eredimus, the River Po, a southern constellation, * GLOSSARY, | 5 || Ether, a light volatile fluid. Eacww.ia, (plural exuviae,) cast-off substances, slough, lava. Evolved, unfolded, opened, expanded. F. Firmamental, relating to firmaments. (See p. 8.) Fortuitous, accidental, casual, without contrivance. Focus (foci, plural), a central point where rays meet aſter pass- ing through a lens, point of concentration. Fossil, remains or relics of organic bodies found under ground, petrifactions. Fiocculi, flakes or locks of any thing, as of Snow, wool, or clouds. Fac-simile, a perſect copy, exact imitation. Fantastic, capricious, ideal, irrational. Furtive, stolen, thievish. Fiaced Stars, stars thus called, because they do not appear to change their relative situations, and shine by their own light. (see Note #) Flora, flowers, plants, or a treatise upon either. Finder, a small telescope attached to a larger, for the purpose of finding particular celestial bodies to bring them into its field. Fossil Geology, relating to, or history of fossils; the part of geo- logy proper, referring to this subject. - Fossiliferous, of the nature of fossils, containing fossils. G, Great Bear, vide Ursa Major. Geometer, one skilled in geometry, a geometrician. Globular, round, spherical, like a globe. Germ, sprout, branch, first principle. Gravity, the property by which all terrestrial bodies are attracted in perpendicular lines to the surface of the earth, and toward its centre. This #ºnciple also operates in all the celestial bodies. (See Note I.) Generalization, arrangement of particulars under general heads. Germinant, sprouting, branching, first emenation of power or prin- ciple. Gaseous, partaking of gasses, or aeriform fluids, gºal. relating to Geology, the nature and structure of the earth. Groups of stays, are collections nearly equally compressed, and without definite form. They do not exhibit a central attract- ive force, but are distinct and separate from other stars, show- ing that they constitute perfect systems. Gemini, the Twins, a constellation in thc zodiac. Genera, in Natural history a division, family or kind. Animals, plants, and minerals, are divided into classes, orders, genera and species. --- 13 152 GLOSSARY, H. Hieroglyphics, emblems, figures implying words, writing in pic- tureS. Homogeneous, having the same nature, principles alike, Hypothetical, supposed, conditional. Hercules, a northern constellation with 113 stars. . . . Hydra, the Water Serpent, a southern constellation, containing 60 stars. - Hyades, stars in the constellation Taurus. Herschel, see note J. Halley, ib. I. Isthmus, a neck or part connecting larger parts. Fnfinitesimal, indefinitely divided, smallest division of matter. Inherence, state of being inmate, inborn, or inseparable. Incommensurable, not to be measured. Insulation, state of being separated, not contiguous on any side. Isolated, alone, detached. Irresolvable, incapable of being analyzed; defined, or perceived as distinct objects. Interstellar, between stars, intervening spaces. Interjacent, intervening, lying between. Juno, one of the Asteriods, the sixth planet in order from the sun. Jupiter, a superior and the largest planet of the Solar system ; it has 4 moons. - Inferior, in the solar system smaller than the earth. Indices, (Index, singular,) pointers, discoveries. Intractability, incapability of being altered, unmanagability, Indurated, hard, petrified. Infusoria, animalculae, the class found in stagnant water and in- visible to the naked eye. Inertia, inertness, disposition to continue as placed, at rest or in motion. Incipient, first, earliest state. L. Law of velocities, Laws of accelerated motion, by which the ve- locity is increased in proportion to the weight as multiplied into the distance. Falling bodies receive new impulses of at- traction at every instant, as though no motion had already been acquired. And the motion is as the square of the times employ- ed in falling, viz.: * Seconds of time. .... 1 2 3 4 5 etc. Their Squares....... 1 4 9 16 25 “ Feet of motion....... 20 80 180 320 500 “ Luminary, a body giving light, a celestial body. Leo, “the Lion,” a constellation of the Zodiac with 95 stars. y §º- GLOSSARY. 153 Libra, the Balance, a constellation of the Zodiac with 51 stars. When the sun enters this sign the days and nights are equal. Logical, according to rules of logic, correct writing, &c. Lyra, the Harp, a northern constellation with 22 stars; a star of the first magnitude. . Lateral, on the side, sidewise, parallel. Leonis, star in the constellation Leo or Lion. Lºwmar, relating to the moon. Lens, a glass or metalic body used in aiding sight, a spherically convex glass. Linear, composed of lines, having the form of lines. M. Meteors, transitory luminous bodies in the air or sky. Microscopic, relating to the properties of the microscope, an in- strument for magnifying small bodies by an arrangement of glasses or lenses, to be seen only with the microscope. Myriads, tens of thousands. Momentum, the impetus, or force of a moving body, made up of weight and velocity. * { Monograph, only, a treatise on a single subject. Minutia, details, smallest particulars. - Magnitudº, the relative size of the stars as they appear to us. There are six or seven degrees of magnitude as seen by the naked eye and many more as seen through a telescope. Mars, the fourth planet from the Sun in the Solar system and without satellites: Mercury, the first planet from the sun, inferior and without Satellites. - Mythological, relating to the fabulous, though sometimesbeautiful stories and theories of the ancients. Magellamic Clouds, whitish appearances like clouds, having the same apparent motions as the stars, and about 11 degrees from the south pole. º Milky Way, Via Lactea, or Galaxy, the broad white path or cloud, seen as such by the naked eye, and varying in width from 5 to 16 degrees, but ſound by the telescope to consist of innumerable stars (8 or 10 millions at least) and assemblages of nebulae and clusters of stars, the mingling light of which evolve whiteness. (See Note G.) Mineralogical, belonging to minerals, or specimens of rocks. Metalic bases, metals, combined with oxygen, for which they have so strong an affinity as to burn with an intense flame when exposed to the air, forming oxides of the earths. When separated from their oxides, by means of the Galvanic Battery, —first performed by Sir H. Davy—they are placed in Naptha to prevent combustion. Thus the base of silex, or flint, sand, rock- crystal, &c., is silicium ; that of allumine, clay, or alumi, is aluminum; that of potass, potassium; that of lime, or lime-stone, calcium, &c, ,154 GLOSSA.R.Y. , N. Nebula, (Nebulae, Nebulosities, plural) Telescopic stars, a celes- tial body seen by the naked eye, as a thin luminous cloud, but consisting of innumerable stars as in the Milky Way. (See Note G.) Nebulous, Nebular, partaking of the character of nebulae, applied to stars showing a dim light. Nucleus, (Nuclei plural) the kernel, a centre, the point about which matter collects or moves. - Nebecula, Major and Minor, Nebulae, large and Small. Newton, (See Note J.) O. Orion, a northern constellation and one of the most remarkable in the heavens; it has 78 stars. Optical, relating to optics, vision, or phenomina of light. Orbit, the path in which planets move, the curvilinear track or course pursued by any of the heavenly bodies. Orbitual, relating to an orbit, or path, as above. Orbicular, circular, spherical. Orrery, machine to represent the motions of planetary bodies, so named in honor of the Earl of Orrery. Oscillatory, moving backward and forward, like a pendu.um. Observatory, a place or building fitted up and provided with pro- per instruments for observing celestial bodies. Oxygen, one of the two parts of the atmospheric air and of water, in the proportion of 85 to 15 of hydrogen in the latter, and about 26 to 74 of nitrogen in the former. It is the supporter of life and combustion and forms rusts, or oxides, by combination: it is called the acidifying principle in forming acids, &c. Organic remains, remains of organic bodies in a mineralized State, fossils, both animal and vegitable. P. Pleiades, or “seven stars,” a cluster of stars in the constellation Taurus, and in the neck of the Bull; one is invisible to the naked eye. Periodicity, periodical occurrence, happening at definite or perio- dic times. Picturesque, happily expressed, as by a picture, a natural and va- riegated view. Phenomena, extraordinary appearances, the occurrence of re- markable events in nature. - Parasitic, attached to, depending upon and nourished by another, a flatterer. Planets, bodies revolving around the sun, and known from the fixed stars by their change of situation, t Prozimily, nearness, neighborhood. GLOSSARY, 155 Planetary, relating to planets. Pertubation, disturbance, disorder, disquietude. Physical, relating to nature, natural philosophy. Profund-ties, greatest depths of space or knowledge. P. (Phases, plural,) face, appearance or change of celestial bodies. - - * Pallas, one of the Asteriods, the eighth planet in order from the sun. Plane, a level, joining two points by a straight line, extended even,surface. Perseus, a northern constellation, with 59 stars. Pioneering, going before, preparing the way. - Plastic, capability of forming, or moulding, or of being formed. Primary, first, formed before; in geology the granitic family of rocks, without organic remains. Procyon, a star of the first magnitude, in the constellation Canis Minor. Pristine, first, ancient, original. Phantasmagoria, magic lantern, magnifying transparent objects. Problem, question to be solved, proposition. - Primeval, original, first, primitive. Physiology, the constitution of organic bodies, their natural func- tions, * Q. Quadruple, relating to, or consisting of four. Quintuple, relating to, or consisting of five, * R. “, f Reflector, a glass or instrument for reflecting light, a telescope. *::::::: a glass or instrument for refracting or bending rays of light. Rotation, revolving motion, whirling like a wheel. Refrangible, capable of being bent or turned aside. Radius, (Radi, plural) a line drawn from the centre to the eir- cumference of a circle. Rationale, an inference, reason, or conclusion from details. Retina, expansion of the optic nerve, back coat of the eye. Regulus, a star of the first magnitude in the constellation Leo. Radiating, spreading out, branching from any point. Ratiocinaliom, reasoning, deduction of consequences. Resolvable, that which may be analyzed, brought together and explained or defined. Right Ascension, the point of the equinoctial which comes to the meridian of any celestial body. Reticulated, formed like net work. Retardation, hindrance, act of delaying. Sun's Equator, its apparent path in the heavens, or central line. 156 GLOSSARY. Satellites, small or secondary planets, or dependent bodies moving around larger. Stratum, (Strata, plural,) layer, or bed. Spectrum, image of 7 different colors produced by light passing through a prism. --- Sagittarius, “the Archer.” a constellation of the zodiac with 69 StarS. Sibyline, like the ancient oracular priestess of Apollo; deceitful. Solar, relating to the sun. - Star Dust, clusters of small stars appearing like sparkling sand. Sphere, a globe, an orb or circuit. Sphericity, rotundity, roundness. Statistics, statements, facts in detail. - Speculum, (Specula, plural) glass or metalic body reflecting rays of light. - Segment, part, or an arch of a circle. Spectral, relating to a spectre or ghost, frightful, unnatural. Superior, in the solar system larger than the earth. Stellar, relating to stars, - Synonyme, the same thing in meaning, or another word for the same signification. Stratification, formed in layers or beds. Stariness, partaking of stars, appearing like stars. Saturn, a superior planet, the tenth in order from the Sun, with SIX II). OODS. Scorpio, a constellation of the zodiac containing 44 stars. Sirius, “the Dog Star,” one of the brightest in the heavens, is in the constellation Cani Major. Spica, a star of the first magnitude, in the constellation Virgo. Space-penetraling, capability of penetrating space, power of dis- covering into the depths of firmaments. Scorpio, the Scorpion, 8th sign in the zodiac, 44 stars. Supervene, to occur unexpectedly, additional, to follow or come between. - Sideral, starry, belonging to stars. ' Subtend, to reach across, between two lines which make an angle. s: 4th division, in natural history. (See genera.) Sºperposition, in geology, the succession of Strata in the forma- tion of the earth, or the natural order in which they overlie one another. Secondary, in geology, a series of rocks succeeding the primary and transition rocks, or including the latter in part. T. Triple, relating to three, . Trapezium, a figure with four unequal sides, the nebula discov- ered by Huygens in 1656, between the two stars in the sword of Orion, as a bright spot on a dark field. Tracery, the following of outlines, tracing of figures. G LOSSARY, 157 Talisman, magical character. Termary, consisting of three, proceeding by threes. Transit, passage of a planetary body over or just by another. Taurus, “the Bull,” a sign of the Zodiac, with 141 stars. Transmutation, change into another nature or substance. Toucani, the American Goose, a southern constellation. Testacea, shell-fish, having thickshells, as the oyster, muscle, &c. Torrid, hot, parched, violent. - Transition, a series of rocks following the primary rocks, and made up in part of both these and the Secondary. They were formed during a general revolution of the earth's surface, and in its transition from an uninhabitable to a habitable world. * U. (Jnoxidated, not rusted, corroded, or tarnished, uncombined with Oxygen. Undulations, waving or unsteady motions. Jramus, Georgium, Sidus, or “Herschel,” a superior planet, dis- covered by Dr. Herschel, and the most remote in the solar system. Ursa Major, or “Great Bear,” a northern constellation, with 87 StarS. Orsa Minor, “Little Bear,” a constellation near the north pole, with 24 stars, one of which is the Polar Star. V. Visual, relating to sight, power of sight. Visibility, state of being seen, power of discovering by sight. Vistas, views or prospects through spaces, as through avenues, between trees, &c. Venus, an inferior planet, second in order from the sun. Vesta, one of the Asteriods, the fifth planet in order from the sun. Virgo, a constellation of the Zodiac, with 110 stars. Virginis, a star in Virgo. Vega, a star of the first magnitude in Lyra. W. Woodiness, appearance of woods, or clusters of trees. Z. 20ne, a girdle, a division of the earth or heavens: there are five in number, viz.: 2 frigid, 2 temperate, and 1 torrid zone. . Zodiacal, relating to the Zodiac, great circle of the sphere, signs, &c, 158 GLOSS ARY. Zodiac, a belt or girdle surrounding the heavens, within two parallel circles, through which runs the ecliptic: it is the mid- dle zone, and is about 16 degrees broad. It includes the orbits of all our solar planets, except those of Ceres, Pallas and the moons of Herschel, or Uranus. It is the circle which the earth annually describes, as seen from the sun, and which the Sun ap- pears to describe, as seen by us: it has 12 signs or constella- tions. The region, or zone, north of this has 37, and that on the south, 47 constellations. L. D. C. NoTE.—On comparing the re-publication with the original text, it will be seen that many slight alterations have been made in words and points of punctuation; yet it may not escape notice that a few errors have occurred in the Notes and Glossary, for which, it is presumed, a reasonable apology will appear in the fact that they were written and examined near the close of the publication, dur- ing the hurry of proof-corrections, attention to the execution and ‘correction of the plates, with other immediate engagements, and therefore without an opportunity to consult authorities or to regard the phraseology, in which some errors of the press are perceived. This is all that is deemed necessary in the form of an errata, THE END, e. • * . . * * * * THE UNIVERSITY OF MICHIGAN . GRADUATE LIBRARY DATE DUE \ ###!!! º ſ : & |ºº Đ ** , º * . º D ºº {N -.t : & A | | º i \, , || | | |