g 68 Dr. Herschel's Account of the Changes that have happened 
( g ) That we cannot allow O and x to be the two bodies in 
motion, follows from the insufficiency of the solar motion to 
account for that of y, which must be real, or at least partly so. 
( h ) If O and y are the moving bodies, the given situations of 
x, in the years 1782 and 1783, point out an apparent motion of x, 
which must be intirely owing to the solar parallax; and, therefore, 
those who will admit this hypothesis, must grant the discovery 
of the motion of the solar system, and of the proportional pa- 
rallax of the two stars y and x. Let us however examine whether 
any motion of the sun, such as we can admit, will account for 
the change of position and distance pointed out by my observa- 
tions of the small star near y Leonis. 
The joint effect of proper motion and parallax, has carried y 
from its situation in 1782 to that where we now find it. The 
small star, having all this time, in appearance, accompanied y, 
must have gone through a space of 7", 98, in a direction which 
makes an angle of 8° 30' south following with the parallel of y, 
in order to be at its present distance from it, and at the same 
time to have undergone the required change of its angle of po- 
sition. Now, as the supposition we are examining requires this 
small star to be actually at rest, it will be necessary to assign to 
the sun an opposite motion of the same velocity, in order to 
make that of x only an apparent one. The consequence of this 
will be a retrograde motion of the sun, which it is well known 
cannot be admitted. 
Motion of the three Bodies. 
(/) A motion of all the three bodies, is the only way left to 
explain the phenomena of our double star; and I shall now 
again point out the very particular circumstances which it is 
