276 HUBERT ANSON NEWTON. 



course of these comets, as described by the annalists, was in the line 

 of the Leonid stream.* 



This identification of comets with meteors or shooting-stars marks 

 an epoch in the study of the latter. Henceforth, they must be 

 studied in connection with comets. It was presumably this discovery 

 which led Professor Newton to those statistical investigations 

 respecting comets, which we shall presently consider. At this point, 

 however, at the close as it were of the first chapter in the history of 

 meteoric science, it seems not unfitting to quote the words of an 

 eminent foreign astronomer, written about this time, in regard to 

 Professor Newton's contributions to this subject. In an elaborate 

 memoir in the Comptes Rendus, M. Faye says, with reference to our 

 knowledge of shooting-stars and their orbits, " we may find in the 

 works of M. Newton, of the United States, the most advanced 

 expression of the state of science on this subject, and even the germ, 

 I think, of the very remarkable ideas brought forward in these last 

 days by M. Schiaparelli and M. Le Verrier." t 



The first fruit of Professor Newton's statistical studies on comets 

 appeared in 1878 in a paper "On the Origin of Comets." In this 

 paper he considers the distribution in the solar system of the known 

 cometic orbits, and compares it with what we might expect on either 

 of two hypotheses : that of Kant, that the comets were formed in the 

 evolution of the solar system from the more distant portion of the 

 solar nebula ; and that of Laplace, that the comets have come from the 

 stellar spaces and in their origin had no relation to the solar system. 



In regard to the distribution of the aphelia, he shows that, except 

 so far as modified by the perturbations due to the planets, the theory 

 of internal origin would require all the aphelia to be in the vicinity 

 of the ecliptic ; the theory of external origin would make all direc- 

 tions of the aphelia equally probable, i.e., the distribution in latitude 

 of the aphelia should be that in which the frequency is as the cosine 

 of the latitude. The actual distribution comes very near to this, but 

 as the effect of perturbations would tend to equalize the distribution 

 of aphelia in all directions, Professor Newton does not regard this 

 argument as entirely decisive. He remarks, however, that if Kant's 

 hypothesis be true, the comets must have been revolving in their 

 orbits a very long time, and the process of the disintegration of comets 

 must be very slow. 



In regard to the distribution of the orbits in inclination, the author 

 shows that the theory of internal origin would make all inclinations 

 equally probable; the theory of external origin would make all 



* Amer. Jour. Sci., ser. 2, vol. xliii, p. 298, and vol. xlv, p. 91, or EncycL Britann., 

 article Meteor. 



t Comptes Rendiis, t. Ixiv, p. 551. 



