92 W. A. Norton on Comets. 
sion will still have the effect to diminish, more or less, the curv 
ture of the orbit. 
The trajectory at the remoter distances from the nucleus may 
also be obtained, by the ordinary theory of projectiles, if wel 
gard the particles as projected from the point where its orbit be- 
comes parallel to AB, and with the velocity which it there ha 
As the angle of emission, a, becomes quite small, this concept? 
would lead to less accurate results. 
We have hitherto supposed the particle, emitted from the sur 
face of the nucleus, to have no initial velocity. If we me 
it to be projected with any velocity V, this velocity may ie . 
garded as having been acquired in moving from a point at 4 
tance : from the centre of the nucleus; and proceeding with the 
investigation as before, we obtain in place of equ. (2) 
tdi 
Z=n 2 RCT . . - (11) 
a sphere whose radius is “, and that the particle leaves its 
face without initial velocity. — : 
Let us now suppose, for the moment, that the particle is P 
jected from the nucleus, and is subject only to the attraction 
