Motion of the Sun , and solar System. 24 7 
The distance of Capella from the same calculated apex of 
the solar motion, by which we have already explained the 
apparent motions of the other two stars, is 8o° 54' 46"; and, 
admitting again the velocity of the sun towards the same point 
as stated before, it will occasion a parallactic motion of Capella, 
in a direction 89° 54' 48" south-following its parallel, amount- 
ing to 2", 8 1 25. In this calculation Capella has been taken for 
a star of the first magnitude, supposing its distance from us to 
be equal to that of Arcturus. 
By constructing then a triangle, the three sides of which will 
represent the three motions which every star must have that 
is not at rest in space ; we have one of the sides, representing 
the apparent motion of the star, equal to o",y 637 ; the other 
side, being the parallactic motion of the star 2 ,/ ,8i25 ; and the 
included angle 18 0 19' 27". From these data we obtain the 
third side, representing the real motion of the star, which will 
be 2", 3757. By the given situation of this triangle with respect 
to the parallel of declination of Capella, the angle of the real 
motion will also be had, which is 86° 34' 11" north-following 
the parallel of this star. A composition of the parallactic and 
the real motion in the directions we have assigned, will produce 
the annual apparent motion which has ' been established by 
observation. 
But to apply what has been said to our present purpose, it 
may be observed, that although we have accounted for the 
proper motion of our third star by retaining the same apex of 
the solar motion, which has given us an explanation of the 
apparent motions of the other two, yet in doing this we have 
been obliged to assign a great degree of real motion to Capella ; 
and to this it may be objected, that we can have no authority 
