Camera ObsCura Microfcope. *22 
The Apparatus for this Purpofe, as repre- 
fented in the Plate annexed, is as follows. 
A. a fquare wooden Frame, thro’ which 
two long Screws pafs, and, aftifted by a cou¬ 
ple of Nuts 1. 1. fallen it firmly to a Win- 
dow-lhutter, wherein a Hole is made for 
its Reception ; the two Nuts being let into 
the Shutter, and made fa ft thereto. 
A circular Hole is made in the Middle of 
this Frame, to receive a Piece of W ood of a 
circular Figure, B, whole Edge, that pro¬ 
jects a little beyond the Frame, compofes a 
fhallow Groove 2, wherein runs a Cat-gut 3 5 
which, by twilling round, and then crofting 
over a Brafs Pully 4 (the Handle whereof, 
5, palfes thro’ the Frame) affords an eafy 
Motion for turning round the circular 
Piece of Wood B, with all the Parts there¬ 
to affixt. 
C. is a Brafs Tube covered with Seal- 
Skin, which, fcrewing into the Middle of 
the circular Piece of Wood, becomes a 
Cafe for the uncovered Brafs Tube D. to 
be drawn backwards or forwards in. 
E. a fmaller Tube of about one Inch in 
Length, cemented to the End of the larger 
Tube D. 
ufed, I took care that the laid Drawing and Defcription, 
with what other little Additions appeared neceffkry to render 
the book more perfect, fhould be prefented to them gratis , 
upon applying to thofe they bought them of. But no fuch 
Care is requifite at prefent, this Impreffion being printed from 
the fecsnd , without any Difference of Confequence. 
