§8 M i c r o s c o p i c a l E s s a y s .
the objeft; regulate the focus o f the magnifier by the fcrew O.
The moft pleafingmagnifiers in ufe are the fourth and fifth.
The fize o f the objeS may be inereafed or diminished, by
altering the diftance o f the fereen from the microfeope: five or fix
feet is a convenient diftance.
T o EXAMINE TRANSPARENT OBJECTS OF A LARGER SIZE
or to render the inftrument what is ufually called a megalafcope,
take out the Aider, Fig. 3, from its place at n, and Tcrew the button,
Fig. 4, into the hole at P, Fig. 2, and remove the glafs
which is under the plate at m, and regulate the light and focus
agreeable to the foregoing direftions.
N. B. A t the end o f the tube G there is a lens for increafing
the denfity o f the rays, for the purpofe o f burning or melting any
combuftible or fufible fubftance; this lens muft be removed in
moft cafes, left the objefts fhould be burnt. The intenfity o f the
light is alfo varied by moving this tube backwards or forwards.
A pparatus of the opake S olar Microscope.
The large fquare plate and mirror.
The body o f the microfeope.
The opake box and it’s tube.
The tooth and pinion microfeope^
The
The Aider with the magnifiers.
The megalafcope magnifier.
The two ferews Q and R.
Some ivory Aiders.
Some Aiders with opake objects.
A brafs frame, with a bottom o f foft deal to ftick any object on.
A brafs cylinder K, Plate IX. for confining opake objefts.
D escription o£ the common Solar Microscope,
Fig. 4, Plate VI.
The foregoing defeription will, in a great part, anfwer for this
microfeope; and I once intended to have made only fome general
references to the former, in order to avoid that prolixity which
muft ever attend the detail of defeription : but when I confidered,
that one o f thefe inftruments might be purchafed by thofe who
would probably never fee the other; and that a fmall difference
in conftruction would embarrafs the young praftitioner, it appeared
to me more eligible to give a defeription o f the common
folar at full length, than to curtail it through an affeflation of
brevity.
This inftrument is reprefented in Plate VI. at the Figures 4,
5> 6, 7. 8.
N 2 A B