4© The Size of ObjeBs 
ObjeCt-Lens is greatly increafed by the Ad** 
dition of two Bye-Glaffes ; but as no ObjeCt- 
Lens can be ufed with them of fo minute a 
Diameter, or that magnifies of itfelf near fo 
much as the Lenfes we can ufe alone, upon 
the whole, the Glaffes of this Double Micro- 
fcope magnify little or nothing more than 
thofe of Mr. Wilson’s Single one. And 
the fame Table which fhews the Powers of 
the Glaffes belonging to that Microfcope s 
may ferve for thefe alfo. For the firft Glafs, 
fecond Glafs, &c. of either Microfcope,-mag¬ 
nify pretty much alike; and the chief Ad¬ 
vantage arifing from a Combination of Glaf¬ 
fes is, the Sight of a large Field or Portion 
of an ObjeCt, magnified in the fame Degree, 
G FI A P. X. 
To find out the real Size of Objects fieen 
by Microfcopes . 
T il O’ by the preceding Directions the 
magnifying Powers of Microfcope - 
Glaffes may eafily be underftood, it will ftill 
remain uncertain (if the ObjeCts we examine 
are exceedingly minute) what the real Big- 
nefs of them is. For though we may know 
they are magnified fo many thoufand Times, 
we can make by that Knowledge but a very 
imperfed Computation of their natural and 
true 
