The Mi cr of cope explained. liil 
then adding the fourteen parts of the next revolution 
we obtain the 534 thoufandth parts of an inch, which, 
is the meafure of the image of i-ioth of an inch mag¬ 
nified at thg aperture of the compound microfcope, or 
rather the field of view to be equal to the meafure of 
5-ioths and 34-iocdredths parts of another tenth. 
And as we fuppofe the compound focus of the two eye- 
glaffes in the variable microfcope to be one inch 2-ioths* 
zz 1,20, its double will be equal to 24P thoufandth 
parts of an inch for the diftance of the eye from the 
image, or from the needle-point of the micrometer._ 
Again, if we take the diftance of the image, from the ob¬ 
ject on the ftage which is 6, 40-100 inches equal to 6, 
40 thoufandth parts of an inch, and add thereto 240, 
double diftance of the focus of the eye-glaft, we fhall 
have 880 thoufandth parts of an inch for the diftance of 
the eye from the objedt, and from the property of the 
eye-glafs in doubling the image, we muft alfo double 
the number 534, found upon the micrometer which 
pukes 1068, then by the following analogy, fay; 
As 240, the diftance of the eye from the image, is to 
880, the diftance from the eye to the objedf :: fo is 1068, 
the double of the meafure found on the micrometer, to 
39,16 the number of times the microfcope magnifies the 
diameter of the objedt. 
Having thus obtained the magnifying power of all the 
magnifiers when applied to the compound microfcope, by 
(hewing how much the objedt is magnified ; the next 
ftep to be confidered is to calculate a table of the powers 
of every (ingle objeft lens, of the particular microfcope 
the reader may be poflefied of, becaufe it is almoft im~ 
poifible to work two deep magnifiers, that (hall be pre- 
cifely of the fame focus; therefore the table I have here 
fubjoined, will not aniwer every microfcope, but may 
nearly aniwer the variable microfcopes which I make. 
The 
