[ j8 ] 
ency made for its Reception at the End of the 
Tube K. If the Objedt does not appear quite 
diftindt, a fmall Turn or two of the Screw to 
which the Magnifier is fixed, will adjuft it to a 
very great exadtnefs. 
Obfervation muft be made, that as the Sun is 
in continual Motion, it will be required often to 
have the Looking-glafs moved like wife ; which 
by a little Pradtice is eafily done to the greateft 
Nicety ; for the Diftindinefs of the Objedt de¬ 
pends greatly on the Sun’s Rays, being thrown 
exadtly through the fmall Lens, which a fmall 
Turn of the Button H will eafily do. 
The propereft Magnifiers For this Ufe is the 
Firft and Second. 
This Apparatus anfwers the purpofe for a Ca- 
mera-Qbfcura, much preferable to the Ball and 
Socket ; as by the Affiftance of the Looking- 
glafs, Objedts are received at any Angle, and 
thrown in a diredt Line ; and if the Objedt is un¬ 
derneath the Looking-glafs, it is thrown on the 
Screen eredt. The Tubes (in this Experiment) 
are not made ufe on, and the Objedt Lens muft 
be placed in the Brafs Cell next the Looking- 
glafs, the other being firft taken out. 
FINIS. 
