672 



KNOWLEDGE 



[May 5, 1882. 



THE COMET. 



"ITI^E give this week the path of comet Wells to the end 

 V T of next week. We had prepared a map from the 

 orbit given in the circular of the ScMiice Observer, Boston ; 

 but this was incorrect, and we instructed the engravers 

 not to proceed with the map. The path here shown is 

 taken from the positions given by the superintendent of 

 the Nautical Almaiiac. 



THE NEBULA IN ORION. 



Pkoi-. Heney Deapee's Photographs of the Spectscm. 



THE nebula in Orion is, for many reasons, a very interesting 

 body. It is an immense mass of glowing; gas, and presents 

 the same condition that, accordin*^ to the nebular hypothesis, the 

 eolar system did before any planets had been formed. Among 

 these points of interest none is greater than that bearing on the 

 chemical question of the non-elementary character of the so-called 

 elements. If we cximine the spectra of the sixty-eight elementary 

 bodies found on the earth, and group them together, the resulting 

 map contains thousands of lines ; if we look at the spectrum of the 

 sun, a considerable proportion of these lines are found there ; if we 

 observe a certain series of stars, the number of lines diminishes, till 

 in such stars as Vega only about a dozen lines are seen ; and finally, 

 if we turn our spectroscope to the true nebula", only three or four 

 lines remain. Such observations indicate that we are tracing back 

 a process of evolution of the elements, and that from extreme sim- 

 plicity complexity is being evolved. The evolution of the elements 

 proceeds in the yarae way as the evolution of organised structures, 

 the heterogeneous from the homogeneous. 



The investigation of the compound nature of the elements has 

 for some years attracted the attention of adv.incod scientific men, 

 and various attempts have been made to solve the question. 

 Among these we may now mention those of Professor Ilcnrv 

 Draper, who has looked at the problem from the astronomical point 

 of view. As the main hope for the dissociation of our so-ealled 

 elements is from the influence of heat, it is obvious that in the 

 heavenly bodies, where the temperature is far higher than any we 

 can ottAin hero, wo may detect such decomposition. For this 

 reason, for many years. Dr. Draper has been prosecuting this 

 research, and step after step of advance has been attained. 



Inasmuch as hand-work is inade<|uate for the correct and i-cady 

 mapping of spectra, it was plain that if photography could be 

 applied, great advantages would arise. Accordingly, Dr. Draper 

 has constructed a series of instruments of greater and greater 

 delicacy for the successive steps of this research, and beginning 



with sjwctra of the sun many years ago, has photographed the- 

 spectrum of star after star, even down to the tenth magnitude, and, 

 finally, during the past month of March he succeeded four times in 

 photographing the spectrum of a nebula — the nebula in OrioD. 

 Such photographs require careful study before all that they con- 

 tain can be explained, but they constitute ar ^•••»^'^^».^nt advance. 

 One result, however, is obvious, hydrogen declines to be decomposed, 

 and maintains unimpaired its position as an element. Curiously 

 enough, in the same month, the celebrated English physicist, 

 Huggins, has also obtained a photograph of this same nebular 

 spectrum. 



Dr. Draper has also taken photographs of the nebula itself, so as 

 to watch for changes in it, and observe whether the process of 

 aggregation into stars can be detected. Collated with the photo- 

 graphs of the spectrum, they show clearly evidences of such con- 

 densations. — New Yorl: Times. 



[Dr. Draper writes to me as follows : — " I do not get the line at X 

 3,730, of which Dr. Huggins speaks in the April number of the 

 American Journal of Science, but, on the other hand, I photograph 

 h (\ 4,101), and a couple of other lines in its vicinity which he does 

 not get. iloreover, I have found two curious condensations (in the 

 nebula) which give a continuous spectrum, and indicate either com- 

 pressed gas or liquid or soHd. These just precede the tr.ipezium, and 

 do not show themselves as stars on the photographs of the nebula 

 (without spectroscope)." — R. A. P.] 



Littrk. — Littres faith in Positivism arose from the mental 

 quietude it offered on the great metaphysical questions. Negatio» 

 as well as doubt incommoded him. Augusto Conite extricated him 

 from both by a dogmatism which abolished all metaphysic. Follow- 

 ing this doctrine, M. Littre said to himself, " Do not trouble your- 

 self either with the origin or end of things, with God, the soul, 

 theology, or metaphysic." What quietude for this ardent mind, 

 ambitious of traversing every field of knowledge. This quietude, 

 however, has been misconstrued, and apjiearanees have been decep- 

 tive in representing M. Littre as a staunch and resolute atheist. 

 The religions creeds of others were not indifferent to him. " I 

 know too nuich." said he, "of the sufferings and difficulties c( 

 human life to wish to deprive anybody of the convictions which bear 

 him up in every trial." He no more denies the existence of a God 

 than the immortality of the soul. Ue excludes the consideration of 

 the notion from the mind, because he is proclaiming the impossi- 

 bility of scientifically attesting it. For my part, regarding the 

 words progress and invention as synonj-mous, I ask what is the 

 new philosophical or scientific discovery which can remove such 

 great anxieties from the mind r" They seem tc mo essentially ever- 

 lasting, for the mystery enveloping the universe, of which they 

 are an emanation, is itself essentially everlasting. — " Pasteur's 

 Address before the Academy of Science." 



