12 I 
to the 'End of the Brafs Snout at kt There 
are fix of thefe Glafies belong to the Mictof- 
eope, of fo many different Focus’s, or de¬ 
grees of magnifying Power, and are each ufed 
occafionally, according to the fize of the 
Objedt to be examined, which muff be left 
to the Judgment of the Obferver. 
M. A Brafs Cone to fatten in the Shank under¬ 
neath the middle of the Stage* The principle 
Ufe of this Cone is, when any very tranfpa- 
rent Objedts are viewed with the firft, fecond, 
or third Magnifiers: For Experience fhews, 
that by intercepting fome part of the oblique 
Rays reflected from the Concave Looking- 
Glafs, fuch Objedts are rendered much more 
diftindt; particularly in viewing the Circula¬ 
tion of the Blood, of which, in all other Micros¬ 
copes hitherto made, there was no Contrivance 
for to ufe this, in that curious Observation. 
N. Is a hollow Cylinder with its fides open, to 
the End of which, is fcrewed a Concave 
Silver Speculum /, having a round Hole in the 
middle of it. This Cylinder Aiding over the 
Snout of the Microfcope and the top Edge 
fet to the Mark corresponding with the Mark 
on the Magnifier ufed, a ftrong Light be¬ 
comes refiedted from the Silver Speculum on 
any opake Objedt under Examination, The 
Concave or plain Mirror in this, as well as in 
all other Observations, may be either of them 
ufed, as you find by Experience beft anfwer. 
The Silver Speculum is in an Ivory Box, to 
prevent its tarnifhing. 
O: A long Steel Wire, with a pair of fpring 
Tongs 
