Vestiges of the Natural History of Creation With a Sequel

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206 EXPLANATIONS. forms according to which we have arranged them, and wh1c~ seem to indicate the steps of a stupendous progress " 1. Astronomers have never rested their belief in the reality and wide difl'usion of the nebulous matter on the ohjects referred to in the first paragraph, hut on other~ much within the range of our previous vision. ln so far as we have hitherto understood the nature of cluster;;, the telescopic power required to resolve them is nevt>r very much higher than that which first descries them as dim milky spots. But there are many most remarkable ohjccts which, in this essential feature, are wholly contrasted with clus­ters. For instance, the nebula in Orion, as [have fully shown in the text, is visible to the naked eye, as also is the gorgeous one in Andromeda; while the largest instrument heretofore turned to them has given no intimation that their light is stellar, but rather the contral'y ; although small stars aro tound buried amidst their mass. Now, if Lord Rosse's telescope resolves these, and others with similar attributes, such as some of the streaks among the fol• lowing plates, we shall thereby be informed that we have general­ized too hastily from the character of known firmarnents-that Bchemes of stellar being exist, infinitely more strange and varied than we had ventured to suppose; and certainly we shall then hesitate in averring further concerning the existence, or at least the dilfusion of the purely nebulous modification of matter. " 't Lord Rosse's telescope may also, as I have said, disprove reality of our arrangement of the forms of the nebulre as steps ' • progression. And in r('gard to this question, there seem two l d:.scs of objects meriting attention. · · Fint. I shall refer to the nPbulous stars properlv so called, or to that form in which the diffused matter has reached the condition of almost pure fixed stars. Now, of these objects there are two distinct sets, preseJlting at first to the telescope Yery much the same appearance, but in regard of which our knowledge is very different. It will readily be conceived that a distant cluster, with strong concentration about the ~entre of its figure, must, to the telescope which first descries it, look like a star w1th a halo arnund it. When a higher power is applied, that central star, however, will a~mear as a disk, and to a still higher power the cluster will bt'! revealed. A very great numbP.r of what are called nebulous stars are doubtless of this class; and we have hitherto had no means of accurately ascertaining the fact, just because our largest telescopes were required to descry them ; but there are multitudes of others-the true 'photospheres '-quite of a difterent descrip· tion. Many of these are easily seen as fixed stars with haloes of different sizes diminishing to the mere 'bur;' and under the great­est power as yet applied, the apparent central star never expands into a disk, or departs from the stellar character. It is hy its effect on these that the 11ew instrument will at all bear on this portion of the nebular hypothesis. " Secondly. 'l'he foregoing heing our grounds of belief in the existence of nebulc.e-first, in a diffused or chaotic state, and again in a condition proximate to pure stars; the only remaining point has reference to nebulre in an intermediate state- ·when the roundish masses seem to have begun a process of organi't.ation or concentration, and carried it onwards through several st3geJ; a 'tate to which we hav~ every variety of analogon in the vao'jlli NEBULAR HYPOTH~S~. 207 furms and densities of cometic nuclei. Sir William Herschel cer­tainly was not ignorant that round or spherical clusters abound in the skies, which, when first seen, present all the appearances ot such ~e.bulre-nay, h~ grounded on the fact of their approximate sphenc1ty and vary1pg degree~ of coneentration some of the boldest and most engros~ing of his conjectures; nor would hi! have donhted that rr~nltJtudes wh.ich, even to his instruments, seemed only generall1ghts, would, w after times, be resolved· but here, as before, the gist of the question is not, can you res'olve ro~nd n.eb~lre nevP.r resolved before; but caJJ you resolve such as, q u1te Witlun the range of former vision, have contmued intracta· lJle under the sc~utiny of powers which, judging from the aver · age of our expenence, must surpass what ought to have resolved them 1 · "Such ~rc mv vi~ws as to the prE>sent condition of this impor­ta~ t quest.wn; and 1f the.y are correct, it wHl appear that, not­Withstandmg the re~olut10~s achieved by the new instruments, they are, as yet, qUJte as likely-by accumulating new objects b~l~ngiug to th.c t~ree fo~egoing clas~es, and by more surely and d1stw?t~y ~stabhshmg lheu ch.aractenstic features-to strengthen, as to m.vahdate the grounds of the nebular hypothesis. Eagerly, but patiently, let us watch the approaching revelations." Various minor objections have been presented to the nebular .hypoth~sis; but, before ndyerting to any of them, I may .gtv~ a bnef abstract of certain recent experiments, by which It has been remarkably illustrated. Here it is peculiarly important to bear in mind that the phenomena of nature are, if I may so speak, indifferent to the scale D? which they act. The dew-drop is, in physics, the ptcture of a world. Remembering this, we are prepared, tn some measure to hear of a Belgian nrofessor imitating the s?pposed formation and arrangerr[ent of a solar sys­tem, In some of its most essential particulars, on the table of a lecture-rooin ! The experiments were first con­~ ucted by Professor Plateau of Ghent, and afterwards re­peated by our own Dr. Faraday. The. following abstr<l:ct of Professor Plateatt's experi­ments: Is also presented I~ the fift!1 edition of the Vest-iges. lts be1ng repeated here Is, that 1t may meet the eyes &f many who are not likely to see any .edition of that work nesides those from which it is absent: Placing~ a mixture of w~ter and alcohol in a glass bo~, a!lrl therEin a small quantity of olive. oj}, of density pre­Cl~ ely eq.ual to the mixture, we have In the latter a liquid mass reheved from the operation of g..,-avity, and f1·ee to take t~e ex tenor form given by the forces which may act upon It. In P.oint of fact, the oil instantly takes a globu lar form by v utue of molecular attraction. *-\. vertic a ..