73 



The Leonids of 1900. 



By John A. Miller. 



The number of Leonids observed this year was very much smaller 

 than was anticipated. Doubtless many escaped notice because of the 

 bright moonshine and cloudy weather. Still, bearing these facts in mind, 

 the shower was very disappointing. The totale of observations tend to 

 confirm Dr. Johnstone Stoney's prediction that, owing to planetary per- 

 turbations, the stream bearing these meteors would not come nearer the 

 earth this year than one and a half million miles. 



On the mornings of November 14th and 15th my colleague, Mr. W. A. 

 Cogshall, and myself, aided by our students, observed these meteors in 

 order to obtain data concerning— 



(a) The frequency of fall. 



(b) The radiant. 



(c) Duration of visibility; and 



(d) The height at which the meteors appeared and disappeared. 



Ou both mornings the sliy was cloudy until three o'clock, and parts 

 of it were overcast even after that time. Hence our observations for 

 frequency are of small value. However, from 3:52 to 4:22 on the morning 

 of the 14th our observers coimted thirteen meteors. These came from the 

 neighborhood of Leo, but were probably not all Leonids. At no other 

 time were meteors so frequent as then. It was a source of remark, 

 however, that they seemed to fall in groups two or three. That is, 

 when one appeared one or two others followed at short intervals. 



We attempted to obtain a sufficient number of trails of the meteors, 

 photographically, to determine a radiant, but were unsuccessful. Our 

 visual observations for the same purpose were more fruitful. On the 

 morning of the 14th 45 meteor trails were platted; 13 of these were 

 Leonids. Ou the morning of the 15th 41 wei'e platted: 17 of which 

 were Leonids. The radiant obtained from these paths was at the point 

 whose right ascension is 149° and whose declination is 21°. 



A Bergstrom chronoscope was employed to measure the duration of 

 visibility. This instrument measures time accurately to the thousandth 

 of a second, which is much less than the error introduced by the observer 



6— A. OF SCIRNCP. 



