viii The Mi cr of cope explained. 
the mirror to the right or left, and the other raifes or 
deprefies it, fo as to refleft: an horizontal ray of the fun’s 
light through the tubes IK, upon a fcreen of white 
paper placed about five or fix feet from the window, 
which will form thereon a round fpot of light. 
Laftly, flip the tube I into that marked K, together 
with the microfcope and objedfi as before prepared ; and 
if the fun then fhines bright, you will have a diftindt 
image of the objedf upon the fkreen, by turning the 
button at O to remove the magnifier to its proper focal 
difiance. 
There are fix magnifiers in the wheel P Q, which 
turn round for the greater eafe in changing from one 
magnifying power to another. When the room is dark¬ 
ened, all the magnifiers * are numbered, i, 2, 3, Sec. 
the leaft number being the greateft magnifier. 
In the box with this microfcope, there are alfo three 
fhort brafs Aiders, like that marked R, for incrcafing the 
field of light : on the firft is engraved 1 and 2, to fhew 
that this is only to be ufed with the firft and fecond 
magnifiers. The fecond brafs Aider like R, being 
marked with the numbers 3 and 4, are to be ufed with 
the third and fourth magnifiers, and no other; and the 
third having the numbers 5 and 6, is only to be ufed 
with the fifth and fixth magnifiers. This is a principal 
improvement in the folar microfcope, arifing from the 
great increafe of light we obtain thereby. The fame 
advantage is gained when N P, which we call the tooth 
and pinion microfcope, is ufed alone as a fingle microf¬ 
cope. 
We have fhewn above how to form a round fpot of 
light upon the fkreen, but this cannot always he attain¬ 
ed, becaufe the fun’s apparent altitude to the inhabitants 
of 
* We prefer the magnifiers fet in round cells as at Y, tQ 
th ofe fet in a wheel as P Q, 
