602 HANSEN ON THE PERTURBATIONS OF BODIES. 
same, but have all contrary signs, and in which are found the 
cosines instead of the sines. The process arising from the pre- 
ceding expressions is very simple, and in the memoir is besides 
explained by means of a detailed example. 
The expansion of the disturbances produced by the reaction 
of the planets on the sun, according to the principles laid down 
in what has preceded, occupies the remainder of the memoir. 
