Description of L yonet’s A natomical M i c r o s c o p e ,
3« Plate VI.
Fig. 3 reprefents the inftrument with which M. Lyonet made
his microfcopical and wonderful difleftion o f the chenille de faule,
o f which a fpecimen is given in Plate XII. Fig. i , &c. o f this work.
This little inftrument needs no further recommendation; aided
by it, other obfervers may be enabled to diflea other infects with
the fame accuracy as M. Lyonet, and thus advance the knowledge
of comparative anatomy, by which alone the charaaeriftic,
nature, and rank of animals, can be truly afcertained.
A B is the anatomical table, which is fupported by the pillar
N O ; this is fcrewed on the foot C D. The table A B is prevented
from turning round, by means o f two fteady pins ; in this
table or board there is a hole G, which is exa&ly over the center
o f the mirror E F, that is to reflea the light on the o b je a ; the
hole G is defigned to receive a flat or concave glals, on which the
objeas are to be placed that you defign to examine.»
R X Z is an arm formed o f feveral balls and fockets, by which
means it may be moved in every poflible fituation; it is fixed to
the board by means o f the fcrew H ; the laft arm I Z has a female
fcrew, into which a magnifier may be fcrewed as at Z. By
means o f the fcrew H, a fmall motion may be occafionally given
to the arm I Z , for adjufting the lens with accuracy to it’s focal
diftance from the objefl.
Another chain o f balls is fometimes ufed, carrying a lens to
throw light upon the objeft; the mirror is alfo fo mounted, as to
be
be taken from it’s place at K, and fitted on a clamp, by which it
may be fixed to any part of the table A B.
T o use the D issecting T able.
Let the operator fet with his left fide near a light window ; the
inftrument being placed on a firm table, the fide D H towards the
ftomach, the obfervations Ihould be made with the left eye | this
pofition is well adapted for obferving drawing or writing. In
diflefting, the two elbows are to be fupported by the table on
which the inftrument refts, the hands refting againft the board
A B ; in order to give it greater liability, (as a fmall {hake,
though imperceptible to the naked eye, is very vifible in the
microfcope) the difle&ing inftruments are to be held one in each
hand, between the thumb and two fore-fingers. Other circum-
ftances will be learnt from practice; and more will be faid on the
mode o f diffefting fmall objefts in the following chapter.
D escription of D r. W ithering’s B otanical Microscope,
Fig. 1, Plate VI.
This little inftrument is reprefented at Fig. 1, Plate VI. It con-
fifts o f three brafs plates, A, B, C, which are parallel to each
other; the wires D and E are rivetted into the upper and lower
plate, which are by this means united to each other ; the middle
plate or ftage is moveable on the aforefaid wires, by two little
fockets which are fixed to it.
P 2 The