H. A. Newton— Biela Meteors of Nov. 27th, 1885. 425 



any way in which the meteors of 1872 and 1885 could be sent 

 around in such a thin stream as we encountered, and one so 

 near to the plane of the comet's orbit, unless they were a very 

 compact group, and were also very near to the comet, as late as 

 its near approach to Jupiter in 1841-12. If they left the 

 comet before that time the effect of Jupiter would not be the 

 same on the meteoroids as on the comet, and if they at that 

 time formed an extended group, such disturbance as the comet 

 suffered would have scattered the group, and we should have 

 had a much less brilliant star-shower in 1872 and 1885. 



Assuming, then, that the comet and the meteoroids were very 

 near each other, if not united, at the date 1841*5 it seems pos- 

 sible to compute the disturbing forces and the resulting orbit 

 along which some of these bodies traveled from that date until 

 they met the earth in 1872, and also the orbit along which 

 others traveled to meet the earth, Nov. 27, 1885. The ob- 

 served orbits of the double comets in 1845-46 and in 1852 

 furnish the basis of such a computation. Possibly the result 

 will give evidence for or against a resisting medium in the 

 solar system. 



We are moreover entitled to conclude that the process of 

 disintegration of the comet is quite rapid. The non-appear- 

 ance of the comet in recent years has like significance. 



The following is a summary statement of conclusions: 



1. The maximum of the shower was near 6 h 15 m Gr. m. t. 



2. Three hours after the maximum the numbers of meteors 

 had diminished to one-tenth the maximum number, and it is 

 not unreasonable to assume six hours as containing the princi- 

 pal part of the shower. 



3. The total hourly number of meteors visible at one place 

 in a very clear sky, to some one or other of a very large group 

 of observers may at maximum be regarded as 75,000. 



4. In the densest part of the meteor stream where and when 

 the earth encountered it, the space that corresponded to each 

 meteoroid was equal to a cube whose edge was about 20 Eng- 

 lish miles. 



5. The dense part of the stream was not over 100,000 miles 

 in thickness. 



6. The zenithal attraction of the Biela meteors was about one- 

 tenth of the observed zenith distance of the radiant. 



7. The radiant was an area several degrees across. 



8. It is reasonable to suppose that the meteoroids while in 

 the upper part of the atmosphere, before the paths become 

 luminous, change direction by a glancing, due to irregularity 

 of form. After the resistance has developed heat enough to 

 melt or burn off projecting angles of the stones, and the tracks 



Am. Jour. Sci. — Third Series, Vol. XXXI, No. 186. — June, 1886. 



27 



