in the relative Situation of double Stars, Sc c. 367 
and the last, which has been lately taken, is 6 ° 2 1/ south fol- 
lowing. The sum of these angles gives 13 0 58', for the change 
that has taken place in 21 years and 38 days. To account for 
this, we are to have recourse, as before, to the various motions 
of the three bodies. 
Single Motions. 
[а) The motion of x alone cannot be admitted, since it is 
known that y Leonis is not at rest. The annual proper motion 
of this star, according to M. De la Lande, is -f o",38 in right 
ascension, and o",o4 in declination towards the south. 
(б) y cannot be the only moving body; because its mo- 
tion in right ascension only, which, in 21,1 years, at the parallel 
of y, amounts to 7", 49, would have long ago taken it away from 
the small star. 
( c, d , e,) The sun cannot be the only moving body ; because 
its motion in right ascension will not account for that of y Leonis, 
which star therefore cannot be at rest. And, if we were willing 
to give up the former assumed solar motion, in order to fix upon 
such a one as would explain the motion of y, we should be 
under a necessity to contradict the united evidence of the proper 
motions of many principal stars which are in opposition to it. 
Double Motions. 
(/) When two motions are proposed, we cannot fix upon y 
and x for the moving bodies, unless we should set aside the solar 
motion, and this, we know, cannot properly admit of a doubt. 
angle of position is 5 0 24'. This was taken April 18, 1783; and, not being acquainted 
with the motion of the small star, I supposed it to be more accurate than the former 
measure. 
3 B 2 
