98 W. A. Norton on Comets. 
the decrease in the sun’s foree. We must therefore 
of force that decreases as the comet approaches the sun, and 
creases as it recedes from the sun. Variations in the amount 
luminous matter ejected may also conspire with these va 
of intensity of force, to give increased effect. The changes 
supposed may seem to be contrary to what would naturally! 
expected ; I can only say in the way of explanation, that 
accord with the theoretical views which I have been led to adopt 
on other grounds, with regard to the process of evolution 
nebulous matter from the nucleus, and the nature and origit 
the repulsive action. 
If we suppose, in the case of Encke’s, and other similar cour 
ets, that the attraction of the nucleus exceeds its repulsio}, 
the variations in the value of &, as the comet approaches the sul, 
an . . « - an ternate : 
exerted both by the nucleus of a comet and the at 
erty belonging alike to all the particles of the mass 0 #, 
we have the means of readily determining the mass and aveTact 
density of the nucleus. For equ. (8) makes known the 
p to k, and by the law of inverse squares, we may compulé 
—— 2 | 
Which gives «=~ Bm ne tS Ale Se ae 
T have made the computations for the comets named in 
nian table, which contains, also, the data used in the © 
ons. 
Oct. 8th, 
Comet of 1811; Oct. 6th, 
s Comet, 1835 ;Oct. 29th, 
We 
