8 Of the Kinds of Microscopes. 
Microfcopes ; and, on the contrary, Mr. 
Ho oke made all his Obfervations with 
double ones. 
The famous Microfcopes of Mr. Leeu- 
wenhoek are the moil fimple poffible, 
being only a fingle Lens, fet between two 
Plates of Silver perforated with a fmall 
Hole, with a moveable Pin before it, to 
place the Objedt on, and adjuil it to the 
Eye of the Beholder. By thefe he made 
thofe wonderful Difcoveries which fur- 
prized the World fo much, and introduced 
a new Syilem of Philofophy and Reafon- 
ing, as in the Courfe of this Treatife I ihall 
find Occafion more at large to mention. 
There are many pretty little Contrivances 
fold at the Shops for the viewing of fmall 
Objects, which are entertaining as far as can 
reasonably be expected from them: but to 
enumerate all thefe would be a tedious Talk. 
It fhould alfo be a Matter more of Curio- 
fity than Profit, to defcribe the Forms and 
Apparatus of the feveral Kinds of Micro¬ 
fcopes that have been contrived fince the 
firfl Invention of them. I ihall therefore 
confine myfelf to give an Account of fuch 
only in ufe among ourfelves at prefent, as, 
by having a proper Set of Glaifes, gradu¬ 
ally magnifying one above another, are fit 
to make Difcoveries of Conference, 
CHAP, 
