F, a piece o f wood or .brafs, .arched in the manner of the faM
plate, and fallened thereto,
G, -the other end o f the microfcope, where a hollow female
fcrew is adapted to receive the different magnifiers.
H, a. fpiral fpring o f fteel "between the faid end G and the
plates o f brafs E, intended to keep the plates in a due pofition,
and .counteract againft the long fcrew C.
I, a final!turned handle, for. the better holding the inllrument,
which fcrews on and off at pleafure.
T o this microfcope belong feven different magnifying giaffes,
fix o f which are fet either in filver, brafs, or ivory, as, in the
figure K, and are marked 1, 2, 3, 4, 5, 6 : obferve, the loweft
numbers are the greateft magnifiers. L is the feventh magnifier,
fet in the manner o f a little barrel, to be held in the hand for
viewing any larger objeCt.
M is a flat flip of ivory, called a Aider, with four round holes
through it, wherein to place objeEls between two mufcovy talcs.
Six fuch ivory Aiders, and one o f brafs, are ufually fold with
this microfcope, feme with objects placed in them, and others
empty, for viewing any thing that may offer; but whoever pleafes
to make a large collection o f objeCts, may have as many as he
defires. There is alfo a brafs Aider, not expre'fled in the figure,
to confine any finall object, that it may be viewed without crufh-
ing or deftroying it.
M i c r o s c o p i c a l E s s a y s . 105
N is a pair o f forceps, or pliers, for the taking up of infeCts or
other objeCts, and adjufting them in the giaffes.
O, a little hair brufh or pencil, wherewith to take up and
examine a fmall drop o f liquid.
P is a tube o f glafs to confine living objeCis, fuch as frogs,
filhes, &c. in order to difcover the circulation o f the blood!
When you would view an objeCt, thruft the ivory Aider, in
which the faid objeCt is placed, between the two flat brafs plates,
obferving always to put that fide o f the Aider where the brafs
rings are farthefl from the e y e ; then fcrew in the magnifying
glafs you intend to ufe at the end of the inftrument G, and" looking
through it againft the light, turn the long fcrew C C till your
objeCt is brought to the true focal diftance, which you will know
by it’s appearing perfectly clear and diltinCt.
The way of examining any objeCt accurately, is to look at it,
firft, through a magnifier that will fhew the whole at once,
and afterwards to infpeft the feveral parts more particularly with
one o f the greateft" magnifiers ; for thus you will gain a true idea
o f the whole, and all it’s parts : and though the greateft magnifiers
can fhew but a minute portion of any objeCt at once, fuch
as the claw o f a flea, the horn of a loufe, or the like, yet by
gently moving the Aider that" contains your objeCt, the eye will
gradually fee the whole ; and i f any part fhould be out of the
focal diftance, the fcrew C C will eafily bring it to the true focus.
O As