On the Meteors of 12th November, 1833. 167 



would be subject to very great perturbations, sufficient to alter the di- 

 mensions of its orbit at every revolution. It might, for example, by 

 coming into near conjunction with Mercury, have its periodic time 

 greatly shortened, and be compelled, for a long period, to revolve 

 nearer to that planet than it does at present ; and again by coming 

 into a similar position with respect to the Earth, its orbit might be en- 

 larged, and its periodic lime increased, so that it might for a long pe- 

 riod revolve nearer to the earth than before. I am not able at pres- 

 ent to assign the amount of these disturbing forces, but it is easy to 

 see that they exist, and must greatly influence the motions of the 

 body. 



The reader will very naturally suppose that, if a comet had ap- 

 proached so near to the earth, having the plane of its orbit in the zo- 

 diac, it would have been visible, first on one side of the sun, and then 

 on the other, like an inferior planet. There are grounds for believ- 

 ing that such is the fact, and that a body answering to the conditions 

 of the supposed comet, has been seen, at intervals, ever since the 13th 

 of November, and is still (March 31st) visible in the west after sunset. 



By inspecting figure 5, it will be seen, that at the time of the me- 

 teoric shower, the body must have been westward of the sun, and if - 

 visible at all, must have been seen in the east before sunrise ; that in 

 consequence of the greater velocity of the earth, * the comet would al- 

 most immediately afterwards be in such a position with respect to the 

 earth, as to appear very near the sun, and shortly would be seen to the 

 eastward of that luminary, and set after him ; and it would either 

 move onwards before the sun, or backwards so as to disappear from 

 the evening sky, according to the relative positions of the comet, the 

 earth, and the sun. It will be farther manifest, on a little reflection, 

 that a nebulous body of considerable extent, when brought very near 

 to the earth, would cover a large space in the heavens. If, for ex- 

 ample, the body were a comet of an elongated figure, as is usual in 

 those bodies, it might, in certain positions, cover an immense arc in 

 the sky, extending from the meridian to the horizon, or even much 

 farther. We will endeavor shortly to make this matter plain by a 

 diagram. Let us now see if we have any evidence of a body like the 



* At the aphelion, the velocity of the body is determined as follows : 



(semi axis major) ^ : (p er ^ist.) * : : Velocity in the cir. : Velocity in the ellipse. 

 That is, 18.92 miles per second being the mean velocity of the earth, (59.846)£ : 

 (24.692)^ : : 18.92 : 12.15. 



