g6 % 2 Dr. Herschei/s Account of the Changes 
This being admitted, the large star, by its motion, should now 
have left the small one so far behind, that the distance of the 
centres of the two stars, (which Sept. 25, 1781, by a measure 
with my lamp micrometer, was 4" 34,'",) should now be 7", 92; 
while, at the same time, the angle of position ought to have 
increased to 52^ degrees. My last observations, however, give 
so different a result, that this hypothesis cannot be admitted. 
If the small star, which is not so much less than the large one 
that we can justly place it at the above mentioned distance, should 
partake of some parallactic motion, it will then increase the objec- 
tions we have stated ; for, if the effect of it should be only one 
quarter of what it is upon the large star, it will add to the magnitude 
of the angle of position, and increase the distance of the two stars. 
Hence it follows, that, unless we should admit the supposition 
of three independent motions, the high improbability of which 
has been sufficiently shown, we have good reason to believe 
that the large star has, during the 23 last years, carried the 
small one along with itself, in the path it describes, in space; 
both being equally affected by parallax and real motion. If this 
be admitted, a mutual revolution of the two stars will be the 
immediate consequence, when the laws of gravitation are taken 
into consideration ; and the change of position they have under- 
gone, will be a necessary consequence of it.. 
y Arietis. Ill, g. 
This star being only of the 4th magnitude, and of the third' 
class as a double star, we have no reason to expect a great change 
in the angle of position ; and yet, with the assistance of a very 
distant observation, which we have in Mayer's Zodiacal Cata- 
logue, a considerable change may be proved to have taken place.* 
