On the Meteors of 13th 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 time 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, andthe 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) 2. (Per. dist.) ae Velocity in the cir. : Velocity in the ellipse. 
That is, 18.92 miles per second being the mean velocity of the earth, (59.846)é : 
(24.692) 4 :: 18.92 : 12.15. 
