Smith J on a Dissecting Microscope. 11 
In the first place, the stage, which consists of a stout piece 
of mahogany, or a plate of brass, is about seven inches long, 
by five broad — and it is attached to a good firm base, also of 
mahogany, by four brass or wooden pillars about five inches 
high (the two front ones being shown in the drawing), which 
serve the double purpose of supporting the stage, and of 
giving the requisite elevation to the hand-rests, by means of 
notches cut in their sides into which the supports fit. These 
hand rests are about five inches square and one fifth of an 
inch thick and are fixed to the sides of the stage by hinges, 
so that they can be placed at any angle required, by means of 
the supports, which are two pieces of wood or metal fastened 
to the rests, as shown in the drawings ; these supports are 
shaped so as not to interfere with the hands in adjusting the 
mirror, this being one of the points that I have specially kept 
in view in designing the instrument. 
The other parts more immediately in connection with the 
stage are the condenser and the arm for holding the magnify- 
ing lenses ; the former is attached to the front of the stage 
by a moveable arm in which it slides up and down, and when 
not in use it can be taken out of the socket and put away in 
some convenient place ; the horizontal arm carrying the lenses 
has the usual rack-work and pinion adjustment, and may either 
slide in and out as figured in the drawing, or also be fitted 
with a rack- work movement — the arm is turned on one side in 
order to show a slight bend at the end, holding the glasses, 
which I think will sometimes be found convenient, when 
rather a deep trough is being used the sides of which would 
otherwise prevent the lenses from being brought into focus 
with the bottom, a circumstance that has in more cases than 
one proved troublesome to me, as either a lower power had to 
be used or the subject shifted to a shallower trough. Upon 
the base of the microscope is a drawer for holding the lenses, 
knives, and other dissecting instruments, including a small 
glass syringe, which I find an extremely useful addition to the 
apparatus. Above the drawer is placed the mirror, which has 
two sockets, one in the centre for ordinary illumination, and 
one in the front for oblique light, by which the object under 
dissection is brilliantly illuminated on a dark ground — a plan 
in many instances most effective. A very convenient way of 
doing this would be by putting the mirror upon a socket 
moving in a groove — so that it could be at once placed in any 
required position, or when not in use pushed up to the back 
of the instrument, and thus be altogether out of the way when 
the space is otherwise needed. 
Drawing No. 2 shows the microscope as it appears with the 
