37 2 Dr. Herschel's Account of the Changes 
magnitude, a parallactic motion of the largest would account for 
the change of position. 
Near p Bootis. I, 17. 
There is a considerable change in the relative situation of the 
two stars of this double star ; and, by the assistance of p Bootis, 
it is remarkably well ascertained. This star is so near, that it 
may be brought into the same field of view with our double star. 
Sept. 3, 1782, the position was 87° 14' north- preceding ; and, 
about a year before, the situation of ^ Bootis had been deter- 
mined, so that it appeared, from the two measures, that the three 
stars were almost in a line, the small star being, however, 6° 49' 
on the following side. August 30, 1802, the position of the 
small star was 7 6° 14' north-preceding; which, in 39 years and 
361 days, gives a change of 11 6 o'; and it was at the same time 
observed, that when all the three stars were seen together, the 
small one was on the preceding side of the line which joins this 
double star and p Bootis. A parallactic motion of the large star, 
would have occasioned the small one to go in a direct order ; 
but it has had a retrograde motion. 
North-preceding FI. 18 Persei. I, 38.* 
The two stars, August 20, 1782, were situated in a direction 
8° 24' north-preceding ; and, by a mean of two measures, taken 
March 7, 1804, the position was 20° 34'. This gives a change 
amounting to 12 0 io', in 21 years and 399 days. There is pro- 
bably a little increase in the distance of the stars. The first 
observations, with 460, give diameter of either of them, 
• The place of this star is now given in Bode’s Catalogue, where it is the 85th 
Persei. 
