♦ KNO\A^LEDGE ♦ 



227 



By Kichard A. Peoctob. 



With regard to last week's announcement as to the 

 change of Knowledge to a montlily magazine after the 

 last number in September, it has since been found neces- 

 sary to extend the weekly issue until October 16. 



The discovery of a new star in the great Andromeda 

 nebula must be regarded as decidedly a point for us (Mr. 

 Herbert Spencer, Cleveland Abbe, myself, and — well, I 

 know no others) — who have maintained for several years 

 past, that none of the nebulae are external galaxies. For 

 certainly, if there was one exception which even we 

 might have been disposed to make, the nebula in Andro- 

 meda, with its great size, its proved stellar constitution, 

 and its position (not obviously associating it with the 

 stars) would have been selected. 



The Times, which somehow seems unfortunate in its 

 staff writers on scientific matters, has some singularly 

 inexact remarks about the nebula, and the recent change. 

 Thus, it says, " Sir William Herschel inferred, from the 

 fact that some nebulie could not be resolved into stars 

 even with his powerful instruments, that there were 

 many composed of the primeval cosmic matter of the 

 universe." He did so; but this remark, applied to the 

 Andromeda nebula, which has been shown to be stellar in 

 constitution, is rather worse than out of place : it 

 sugges's entirely incorrect ideas. 



Again, the writer in the Times remarks, " The varied 

 forms assumed by nebulae induced Laplace to trace the 

 origin of the whole system to nebulous matter, and this 

 despite the fact that no decided change had been noted 

 in any particular nebula. His idea of the change he 

 illustrated by referring to the trees in a forest, which 

 show no change during a single glance, but show plants 

 in different stages related to each other in order of time, 

 to trace out which in a single instance the life of man or 

 the duration of a solar system would be required." This 

 is an altogether incorrect account of Laplace's views. 

 He was led to his theory of the origin of the solar 

 system, which the Ti7nes writer presumably means when 

 he vaguely speaks of "the whole system," not by ob- 

 serving the varied forms assumed by nebulae, but by 

 observing the nature of the movements within the solar 

 system. It was after he had already suggested and 

 described his hypothesis, which was never regarded by 

 him as a theory, that he recognised evidence in its favour 

 in the varied forms of nebulae. Sir W. Herschel long pre- 

 ceded Laplace in suggesting that, though we might never 

 hope to follow the processes of change by which a nebula 

 passes from one form to another, we might yet recognise 

 them by comparing nebula with nebula as in a garden we 

 compare tires of different age. 



Finally the writer in the Tim-es makes the following 

 remarks : — "In Laplace's theory the sun was surrounded 

 by an immense nebulous envelope or atmosjjhere rotating 

 with it, which extended beyond the f.irlhcst member of 

 our system. From this envrln|ir srMral rings of nebu- 

 lous matter were thrown off, uihI Muse nii-s Unally broke 

 up into globular masses, thus forming tlir iiLinets. It is 

 considered by Captain Abney that the theory of evolution 

 of suns and systems from nebulous matter has received 



strong support from spectroscopic observations. Doubtless 

 the discovery of HeiT Hartwig (sic) will prove a stimulus 

 to observers possessing large instruments, and lead to a 

 careful watch for any similar changes which will aid in 

 the solution, or rather the acceptation, of the nebular 

 theory." This account of Laplace's hypothesis is full of 

 inaccuracies. The sun was not according to that hypo- 

 thesis surrounded by, but formed out of, the immense 

 nebulous mass extending beyond the orbit of the farthest 

 existing planet ; again, if nebulous rings broke up into 

 globular masses, forming the planets, the planets would 

 travel in rings, which they persistently decline to do — 

 only the asteroids adopting that comparatively undignified 

 course. What Captain Abney has found in support of 

 Laplace's nebular hypothesis is not regarded by astrono- 

 mers as amounting to very much : the weight of spectro- 

 scopic evidence points to a theory in which the process 

 imagined by Laplace plays a very subordinate part. 



Lastly the appearance of a new star, or sun, suddenly, 

 in the midst of a mass of already stellar matter, will most 

 assuredly not lead to the "acceptation" of Laplace's 

 hypothesis of the gradual formation of sun and planets 

 out of gaseous matter. Laplace himself, who probably 

 knew something about his own hypothesis, explained 

 clearly, or rather urged strongly, that we must not 

 expect to have any evidence of the actual progress even 

 of such changes as he imagined to have taken place 

 during the embryonic condition of our solar system, — 

 and these changes, even if the occurrence of any of them 

 could have been infinitely hurried, so as to come within 

 human cognisance as observed events, would have been 

 quite unlike what has been observed in the Andromeda 

 nebula. The spectrum of Laplace's nebulous embryon of 

 the solar system would have been assuredly one indicating 

 gaseity and great tenuity — assuming always that that 

 nebulous embryon ever existed : the spectrum of the 

 Andromeda nebula indicates the presence of incandescent 

 solid, liquid, or vaporous masses, shining through 

 strongly absorptive vapours. 



Readers of Knowledge will share 

 Alexander is to leave us, and at thi 



■ regret that Mr. 



With regard to his remarks on Darwin's use of tbe 

 singular number, in the case of the word " progenitor," 

 it would certainly be to misunderstand the theory of 

 natural selection utterly, were we to image that be 

 believed each species descended from a single pair. The 

 whole theory is inconsistent with that idea. It may be 

 remembered that Huxley in reviewing Darwin's " Origin 

 of Species " cited the case of the Ancon sheep as appa- 

 rently indicating the possibility of exceptions to the rule 

 of natural selertinn. For in that case a new species 

 seenu'd In cniiu' into existence per saltum, — in using 

 whicli wnnl I iiitt ml no reference to the alleged conveni- 

 ence (lluxl.y IS the authority) of the great length of the 

 Ancon sheep's body for leaping over hedges and ditches. 

 So also Mivart points to sudden variations as opposed to 

 the principle of development by natural selection. 



The fact is that the idea of races, species, nations, itc, 

 being derived from a single pair, belongs to a very un- 

 developed stage of inquiry. So soon as men begin to 

 recognise the complicated relations involved in such 

 matters, and that such relations must have existed from 



