fhe Magnifying Power of Glaffes . 3 5 
that will give you the Number of Times the 
Diameter is magnified : fquaring the Dia¬ 
meter will give you the Superficies; and if 
it be an Object whofe Depth or whole Con¬ 
tents you would learn, multiplying the Su¬ 
perficies by the Diameter will fhew the Cube 
or Bulk. 
The Superficies of one Side only of an 
Object can be feen at one View; and to 
compute how much that is magnified, is 
mod commonly fufdcient. But fometimes 
it is fatisfadory to know how many minute 
Objects are contained in a larger : as fup- 
pofe, for Indance, I defire to know, how 
many Animalcules would make up the Big- 
nefs of a Grain of Sand. To anfwer this, 
the Cube as well as the Superficies of the 
Animalcules mud be taken into the Ac¬ 
count ; as will be fhewn in the next Chap¬ 
ter. 
As this Treatife is chiefly intended for 
thofe who underhand but little of fuch Mat¬ 
ters, it may neither be needlefs nor unac¬ 
ceptable, to give a Table of the magnifying 
Powers of the convex Glades commonly 
ufed in fingle Microfcopes, according to 
their different Focus: whereby, upon mea- 
fu ring what the bed Didance from the 
Glafs to view the Objed is, its Power of 
magnifying the Diameter, the Superficies, 
and the Cube of an Objed, will be found, 
in one Line. 
d 3 
See 
