256 PIONEERS OF SCIENCE IN AMERICA. 



treme parts of a nebulous body, which revolves around the sun 

 in an orbit inferior to that of the earth ; but little inclined to 

 the plane of the ecliptic ; having its aphelion near to the earth's 

 path ; and having a periodic time of one hundred and eight-two 

 days, nearly." Two of the principal features of this theory 

 those of the cosmical origin of the meteors and their periodicity 

 are still maintained ; but instead of one periodical shower, 

 astronomers now count several ; and instead of a single in- 

 fraterrestrial nebulous body, they connect the several showers 

 each with a particular comet. Priority in putting forth these 

 conceptions was disputed by Chladni, whose claims, however, 

 do not seem to have been so definitely established as those of 

 Prof. Olmsted. Of course, the suggestion of the cosmical ori- 

 gin of meteors, as a suggestion, was never wholly new, for it 

 had been made in general terms by other philosophers, from 

 Anaxagoras down ; but the credit is claimed for Prof. Olmsted 

 of having first embodied it in a definite, coherent theory, ac- 

 companied with valid evidence ; whether or how far Chladni 

 may have anticipated him, his conclusions, as Prof. Silliman 

 well says, were undoubtedly original with himself, and entirely 

 independent of any results of preceding investigations. His 

 work was, furthermore, spoken of in the most complimentary 

 terms by the most distinguished foreign students in those lines 

 of the day. Humboldt referred, in the first volume of his Cos- 

 mos, to the excellent description which Prof. Olmsted had given 

 of the shower in November, 1833, and to his brilliant confirma- 

 tion of Chladni's view that the phenomenon was of cosmical 

 origin. Olbers praised him for his circumstantial description 

 and collection of particulars of the shower, and agreed with 

 him in the conclusion that it came from abroad. Biot, in a 

 communication to the French Academy in 1836, spoke of his 

 " very comprehensive and highly interesting work " in collect- 

 ing and making known " all the circumstances of position, di- 

 rection, and periodicity peculiar to the meteors of the i3th of 

 November." 



In his first memoir on the shooting stars, Prof. Olmsted 

 suggested that the explanation of the cause of the meteors of 

 November i3th might include that of the zodiacal light. He 

 further published a well-matured theory of the nebulous body 

 represented by the zodiacal light. Biot agreed with him in this 

 view, and recognised his priority in the conception. Astronomy 



