420 H. A. Newton— Biela Meteors of Nov. 21th, 1885. 



The contrary effect was indeed so obvious as to arrest the eye 

 whenever simultaneous bursts of about six or seven meteors 

 took place near the radiant. It was then seen that the collect- 

 ive flights were not symmetrical emanations from a central 

 point. They rather appeared to be discharged in a loose, dis- 

 jointed fashion from a comparatively large space on the N.W. 

 region of y Andromeda?, and just perhaps enveloping that 

 star within its limits." Similar testimony is given by other 

 observers. 



"We must then accept one of two propositions : either the 

 luminous paths are not true continuations, unchanged in direc- 

 tion, of the orbital paths of the meteoroids as they approach the 

 earth ; or else these orbital paths make angles of several degrees 

 with their mean direction. The first alternative seems the 

 more probable. 



The meteoroid is probably a fragmentary body of irregular 

 form. The meteorites which come to the ground are fragments, 

 and nothing in their structure suggests a spherical or otherwise 

 regular form upon entering the air. A small irregular body 

 could not traverse with great velocity a fluid, even a fluid of 

 extreme rarity, without there being developed such unsymmet- 

 rical resistance as would cause a curvature of path or glancing 

 of the stone. This unsymmetrical resistance would continue 

 so long as the stone retained its original irregularity. But in 

 time the condensed air in front of the stone becomes hot 

 enough to melt or burn off the stone. The thin angles in front 

 must of course burn first. The melted matter being wiped off by 

 the atmosphere, .the anterior surface is rounded in such manner 

 that the resistance of the air upon the stone becomes symmet- 

 rical. Thenceforth the path, now a luminous trail, is in gen- 

 eral a right line. Curvature of path is an exceptional instead 

 of an ordinary occurrence. 



This rounding of one or more sides of the body is very 

 clearly shown in many meteorites. Thus the Emmet Co. me- 

 teor broke into a very great number of large and small irreg- 

 ular fragments, and the small fragments retained enough veloc- 

 ity to burn after leaving the parent mass. Rounded surfaces 

 evidently produced by the melting and wiping off of the mate- 

 rial by the air are characteristic of these smaller pieces, several 

 thousands of which have been collected. 



The alternative proposition is that each luminous path is a 

 portion continuous in direction, of the meteoroid's orbit about 

 the sun and earth. Upon this hypothesis the orbits of different 

 members of the group are not parallel, but the motions relative 

 to the earth differ in direction by angles which amount in some 

 cases to many degrees. The mean of the deviations from a 

 common direction would be measured by degrees and not by 

 minutes. 



