162 Prot*e88or Denison Obmsted on the 



to a natural phenomenon, which appears to me to have im- 

 portant relations to our solar system, as well as to several 

 of the most sublime and mysterious phenomena of nature. 



In the paper which 1 published in the American Journal 

 of Science in the year 1834, on the cause of the great 

 meteoric shower of November 13, 1833, I inferred the 

 existence, in tlie planetary spaces, of a nebulous body re- 

 volving around the sun, the extreme portions of which, on 

 the 13th of November, lay over or across the earth's orbit, 

 in such a manner that the earth passed throus'h it, or at 

 least near enough to it to attract portions of it into its 

 atmosphere, where they took fire and exhibited the pheno- 

 mena of shooting stars. As the leading steps by which I 

 arrived at this conclusion, after an extensive induction of 

 facts, were very brief and simple, I may be permitted to 

 repeat them here. I argued thus : If all the meteors which 

 fell on this occasion (which were in vast numbers, and some 

 of them proved to be bodies of comparatively large size), had 

 been restored to their original position in space, they would of 

 themselves have composed a nebulous body of considerable 

 extent. But since the same shower had been several times 

 repeated without any apparent exhaustion of the nebulous 

 body, it was inferred that only small portions of that body 

 came down to us, such as constituted its extreme parts 

 which approximated nearest to the earth ; and various 

 reasons induced the belief that the nebulous body itself was 

 one of very great extent. It was a striking fact that the 

 earth had, during several preceding years, fallen in with this 

 body at exactly the same part of its orbit. Now, since it is 

 impossible to suppose that a body thus situated, and conse- 

 quently subject to the sun's attraction, could have remained 

 at rest in that part of the earth's orbit while the earth was 

 making its revolution around the sun, the conclusion was 

 that the nebulous body itself has a revolution around the 

 sun, and a period of its own. Since the earth and the body 

 met for several successive years at the same point of the 

 ecliptic, that period must obviously be either a year or 

 less than a year. It could not be more than a year, for, 

 in that case, the body would not have completed its re- 

 volution so as to meet the earth at the same point for 



