240 Canadian Record of Science. 



meteors of the splendid displays of 1812 and 1885 left the 

 immediate vicinity of that comet later than 1840, although 

 at the time of those showers they had become separated 

 two hundred millions of miles from the computed place of 

 the comet. The process then has been an exceedingly 

 rapid one, requiring, if continued at the same rate, only a 

 small part of a millennium for the completion of an entire 

 ring, if a ring is to be the finished form of the group. 



It may be thought reasonable, in view of this fact about 

 Biela's comet, established by the star-showers of 1872 and 

 1885, to revise our conception of the progress of disintegra- 

 tion of Tempel's comet also. The more brilliant of the 

 star-showers from this comet have always occurred very 

 near the end of the thirty-three year period. Instead of 

 there being a slow process which is ultimately to produce 

 a ring along the orbit of the comet, it certainly seems more 

 reasonable to suppose that the compact lines of meteors 

 which we met in 1866, 1867 and 1868 left the comet at a 

 recent date. A thousand years ago this shower occurred in 

 the middle of October. By the precession of the equinoxes 

 and the action of the planets, the shower has moved to the 

 middle of November. One-half of this motion is due to the 

 precession of the equinoxes, the other half to the perturbing 

 action of the planets. Did the planets act upon the comet 

 before the meteoroids left it, or upon the meteoroid stream ? 

 Until one has reduced the forces to numerical values, he 

 may not give to this question a positive answer. But I 

 strongly suspect that computations of the forces will show 

 that the perturbations of Jupiter and Saturn upon that 

 group of meteoroids hundreds of millions of miles in length, 

 perturbations strong enough to change the node of the orbit 

 fifteen degrees along the ecliptic, would not leave the group 

 such a compact train as we found it in 1866. If this result 

 is at all possible, it is because the total action is scattered 

 over so many centuries. But it seems more probable that 

 the perturbation was of the comet itself, that the fragments 

 are parting more rapidly from the comet than we have 

 assumed, and that long before the complete ring is formed the 

 groups become so scattered that we do not recognize them, 



