*9° Dr. Herschel's Method of observing the 
All the observations contained in this catalogue have been 
made in very fine nights, where no suspicion of any whitish 
haziness or thin clouds can be admitted that might have de- 
ceived me. 
The compound expressions which occur in the catalogue are 
not such as have arisen from want of attention, but on the 
Contrary from more than common and long inspection. 
Whoever looks a long while at two stars which are equal, 
A and B for instance, will find that he is not always pleased 
with the expression A . B, but would incline rather to put 
them down A , B when A seems to have the preference, or 
A ‘ B when the advantage is on the side of B. Since, therefore, 
these three expressions A * B A . B A , B seem equally to 
belong to the stars, my compound character A • B is in that 
instance an useful one, which includes them all. This may 
seem to be a doubtful expression, but it is in fact a very po- 
sitive one, amounting to A = B. For had the stars not been 
perfectly equal, the same causes which bring on these little 
waverings in the appearance of stars, whatever they are, would 
have operated so as perhaps to produce the comparative wa- 
vering lustres expressed by A ; B and AiB or AiB which 
denotes the union of the three expressions A. B and A, B and 
A-B. But if this had been the case, we could certainly not 
admit A = B. 
Sometimes, when I was not willing to put down these com- 
pound marks, I have cast my eyes upon the ground, and after 
a few moments lifted them quickly up to the stars AB, and 
instantly decided which of the expressions ought to be used : 
this being repeated perhaps a dozen or more times, I took that 
expression for the most proper one which would occur oftener 
than any other in these transitory glances. 
