Wilson’s Single 'Pocket Mterofcope. i j 
If your Qbied be a fmali Fifh, place it 
within the Tube, and fpread its Tail or Fin 
againd the Side thereof: if a Frog, chafe 
fuch an one as can but jud be got into your 
Tube, and with a Fen or Stick expand the 
tranfparent Membrane between the Toes of 
the Frog’s hind Foot as wide as you are able. 
When your Objed: is fo adjufted that no 
Part thereof can intercept the Light from 
the Place you intend to view, unfcrew the 
long fcrew CC, and thrud your Tube into 
the arched Cavity, quite through the Body 
of the Microfcope; then fcrew it to the true 
focal Didance, and you will fee the Blood 
pafiing along its Yeffels with a rapid Mo¬ 
tion, and in a mod furprifing Manner. 
Make ufe of the third or fourth Magnifier 
for Frogs or Fidies ; but for the Tails of 
Water-Newts, the fifth or fixth will do; 
becaufe the -Globules of their Blood are 
twice as large as thofe of Frogs or Fifih. 
The firp or fecond Magnifier cannot well 
be employed to this Purpofe; for theThick- 
nefs of the Tube wherein the Objedt lies, 
will fcarce admit its being brought fo 
near as the focal Didance of the Magnifier. 
The Single Mict'ofcope above defcribed 
maybe formed into a Double One , by fcrew- 
ing it to a Tube with an Eye-Glafs at the 
End thereof: it is alfo made to anfwer nearly 
the Purpofes of the large Double Reflecting 
Microfcope, by the Contrivance following 
C H A°P. 
