of ascertaining the Magnitude of small celestial Bodies. 35 
power, will show the disk of a faint object when the angle it 
subtends at the naked eye is no more than 
3d Experiment , with Globules of Silver. 
As the objects made of sealing-wax, on account of their 
colour, did not appear to be fairly selected for these investiga- 
tions, I made a set of silver ones. They were formed by 
running the end of silver wires, the 305th and 340th part of 
an inch in diameter, into the flame of a candle. It requires 
some practice to get them globular, as they are very apt to 
assume the shape of a pear ; but they are so easily made that 
we have only to reject those which do not succeed. 
Thirteen of them, in a pretty regular succession of magni- 
tude, were selected and placed upon the post. Their dimensions 
were ,03956 ,0371 ,0329 ,0317 ,0272 ,0260 ,0187 > 01 7 8 
,0164 ,0125 ,01137 ,00800 ,00 556. 
For the sake of more conveniency I had removed my tele- 
scope from its station in the library to a work-room. The 
distance of the objects from the mirror of the telescope, mea- 
sured with deal rods, was here only 2370,5 inches ; and the 
focal length of the mirror, the magnifying powers of the 
telescope, and the angles subtended by the objects have been 
calculated accordingly. 
With 522,7 I see all the globules, from No. 1 to No. 13, 
■perfectly well, and can estimate the latter in quarters of its 
diameter. The angle it subtends at the centre of the mirror is 
0^,484 ; and one quarter of it is o",iai. 
With the same power I see the wires which hold the balls, 
so well that even the smallest of them may be divided mto 
Fs 
