Ei ye, tiie 
W. A. Norton—Coggia’s Comet. | 173 
distance to which the jets recede in the direction of the sun. 
We may then regard any expelled particle as issuing from the 
small sphere of sensible action of the nucleus with an initial 
velocity resulting from the projectile force of the electric dis- 
charge, and the retarding force of the nucleus (or accelerating 
force if the effective action should be repulsive); and as subse- 
quently retarded by the solar Pe Heeiate s we have seen, p. 
the solar repulsion, its velocity and direction of emergence 
from this sphere, becomes thei{initial velocity and direction. 
RR Ie 
3. : : 
As, for any one molecule, the solar repulsion is sensibly constant 
t 
within the extent of the head of the comet, the p j 
molecule will be parabolic. If we regard the initial velocity 
est rec d 
which suffer the greatest retardation should form a similar 
luminous surface at a lower depth. The latter would eventu- 
