April i i, 1895 ] 



NA TURE 



565 



>?, 



THE SUN'S PLACE IN NATURE} 

 III. 

 n^'HE next question that we have now to consider has lo do 

 with the connection between nebula: and stars, and I shall 

 show that the more the facts are studied the closer does this 

 connection prove to be. ^'o^l remember thtt that was the idea 

 which lay at the bottom of the hypotheses both of Kant aul of 

 Laplace. In the last lecture I referred to s )me of the earliest 

 obgsrvtttions which hail been made of the nebuloe by means of 

 spectroscope, and it so happened that Dr. Hujjgins, to 

 whom we owe this work, came to the conclusion that the result 

 of his inquiries was rather tn shjw that this connection, which 

 had been asserted both by Kant and Laplace, and which had 

 been accep'ed by everybody up to then, really did not exist. 

 In a paper which detailed these spectroscopic observations, 

 published in 1865, Dr. Muggins stated his conclusion that the 

 nebula;, instead of having anything whatever to do with any 

 evolutionary line along which both nebula; and stars might be 

 traced, possessed a structure and a purpose in relation to the 

 universe altogether distinct and of another order. So that you 

 see the first apparent teaching which we got from the spectro- 

 scope practically put us in a very considerable difficulty; if it 

 had to be accepted, of course llie views of Kant and Laplace 

 would have to be rfjected. 



When I commenced my general survey in 18S7, this view held 

 the field, and further, it was imagined that the observati ms of 

 Dr. Huggins justified the idea that the nebula were masses of 



of these singular bodies, the nebul.-e, and the simplicity of their 

 composition, one is led to see in them only the residuum of the 

 primitive matter after condensation int > suns and into planets 

 has extracted the greater part of the simple elements which we 

 find on the earth and chemically in some of the stars." 



It was perfectly clear then to Dr. Wolf that, if the con- 

 stitution of the nebulK was anything like what was supposed 

 to have been revealed by early spectroscopic observation, we 

 were dealing with a residuum. There was one kind of action 

 in space, bringing together one class of elein-nts with which 

 we are fimiliar here, and forming them into stars, suns, and 

 planets ; but there was another kind of matter which declined 

 to form part of these aggregations, which remained by itself, 

 and finally put on the appearance of the so called nebulx. 



The first thing I have to say concerning this view is, that 

 the discussion of the spectroscopic ob-ervations which I told 

 y)u, in the last lecture, had been undertaken with a view of 

 seeing what really could be determined in relatio.i to this 

 question, showed, beyond all ques'i m, that there was no 

 ground whatever for it ; that tliere was no real ground for sup- 

 posing that there w.as this enormou; difierence between the 

 nebula and the stars. In the year 1887, the year following the 

 course of lecture-; to which I have already referred, after test- 

 ing the views on this question by an appeal to all the available 

 observations, I stated that the facts taken in all their generality 

 showed that the nebulae simply represent early stages of 

 evolu'ion ; that is to say, that we have a continuous and 

 orderly progression from the nebulae to the oldest star, and 



Fig. 12. — Spectrum of the nehula inlAndromed.-i conipiired witli Nuv.t .'\n(lromeda; and comet. The tlutings common lo .ill ate those of carbon. 



gas ; what particular gas will concern us a little later on, but for 

 the moment I need only say that these staletnents announcing the 

 nebulae to consist of one or two gases, at once led lo several most 

 rcnarkable views of the general constitution of the heavens. 



Near the end of this nineteenth century chemists claim to 

 know something of the materials which have built up the planet 

 on which we dwell, and if you consult any of the books which 

 have been written about spectrum analysis, giving the results of 

 the work during the last thirty years orso, you will find it stated 

 over and over again that the spectroscope has put it for ever 

 beyond doubt that the chemistry of the skies, i.e. the chemistry 

 of the various bodies which people space, and which are at a 

 sulTicienlly high temperaiure to enable us lo examine them 

 spectrosc 'pically, exactly resembles the chemistry of the earth. 

 So that, il this were true, we should have a common chemistry 

 of the earth, of the stars, and among the star> of course our own 

 sun. On the other hand, we should have, according to Dr. 

 Huggins, absolutely and comidetely distinct from these bodies 

 another class, the nebulie, in which the chemistry is absolutely 

 &nd comfiletely unicjue. This was so clearly the idea suggested 

 to philosophical students of these questions, that Dr. Wolf, a 

 famous I'Veiich astrono ner, who has written an all-imp>rlant 

 book for those who are interested in these inquiries, " Les 

 hypotheses cosmigoniques," pulilished in 1SS6, writes: "If 

 we admit the data of spectrum analysis as to the gaseous state 



' Revis-d fr.^ n tSorttiind n 'tes of a course of Lectures 10 W irking Men 

 At the Museum of Practicil Geology during November and December, 

 t894. (Continued Irom page 39;.) 



that the nebulae represent the first stage, and the oldest star or 

 planet represents the last. It seemed to be perfectly clear from 

 the discussion that we were justified in stating that every 

 nebula which is visible now will some time or other, owing to 

 the condensation of its various parts, become a star of some 

 order or another ; and that it is equally true to say that every 

 star which v\e see now in the heavens, knowing it to be a star, 

 has really been a nebula at some time or another. 



I told you that the first suggestion of a possiblecondition which 

 would enable an evolution to take place from nebulae to stars had 

 been made by Prof. Tail, when he thought that probably cool 

 meleoriiic particles might have something to do with it. The 

 complete inquiry shows that these meteoritic particles might 

 account equally well both for the luminosity of comets and of 

 nebula;. This association is important because it is generally 

 conceded that comtts ate swarms of meteori'es. 



It seemed so obvious that there was this close connection 

 that in 1888 I predicted that, if the nebul.x were carefully ob- 

 served, we should find in them sooner or later indications of 

 that same substance which makes the comet's spectrum so very 

 distinct and special. In almost every comet which has been 

 observed, the spectrum of carbon, or of some compound 

 of carbun, is the strongest and most obvious feature 

 which is presented to us. In 1SS9, i.e. only the next year, 

 matters were made very much clearer by the discovery, by Mr. 

 Fowler and Mr. Taylor, of the spectrum of carbon in the 

 neliula of .\ndromeda (Kig. 12), so that there, you see, was a pre- 

 diction verified, and such verification is always a very precious 



NO I 32S VOL 5 l] 



