D. Kirkwood on certain Harmonies of the Solar System. 9 
with the phenomena observe ; : eae 
Without entering upon any special discussion of this inter- 
esting subject, we respectfully submit the following considera- 
tions: 
investigation of the effects of such a resistance agrees perfectly 
ed.” 8 
1. The hypothesis adopted by Encke in regard to the medium 
which causes the acceleration of the mean motion of his comet, 
is that the density varies inversely as the square of the distance 
from the sun, and that the resistance is proportional to the den- 
nad of the medium and the square of the velocity of the moving 
body. 
* Am. Jour. of Sci. and Arts, Jan., 1864, p. 55. 
Am. Journ. So1.—Seconp Srnres, Vor. XXXVIII, No. 112.—Jurr, 1864, 
2 
