374 Herschei/s Account of the Changes that have happened 
apparent change of place, which must otherwise have happened. 
In this case, no single motion can be admitted to explain the 
phenomena of our double star. But, if a real proper motion of 
e Bootis should hereafter be ascertained, the arguments we 
have used in the case of y Leonis, will lead to the same con- 
clusion. 
Double Motions. 
(/) e and x cannot be the moving bodies ; and our former 
argument (/) will apply to every double star whatsoever. 
(,§•) Oand x cannot be alone in motion ; for, if no motion in 
e can be perceived, it must move in a similar manner with the 
sun, and none of the three bodies will be at rest. But, if its 
proper motion shall hereafter be found out, it must either be 
exactly the reverse of the solar motion, and therefore only an 
apparent one, or it will be more or less different. In the latter 
case, all the three bodies must be in motion ; in the former, the 
exact quantity of the solar motion will be discovered, and the 
relative parallax of many stars may be had by observation. 
(h) If O and e are the two bodies in motion, and if at the 
same time no motion in e can be perceived, then the apparent 
motion of x must be intirely owing to the different effect of the 
solar parallax on s and x ; but the effect of the solar parallax on 
x, can only be in a direction contrary to the motion of the sun, 
which, being north following the small star, whether it be 
nearer or farther from us than e, must have an apparent motion 
towards the south preceding part of the heavens. But this is 
directly in opposition to my observation of the motion of the 
small star, which, these last 23 years, has been directed towards 
the north following. 
