This is an example of a
classroom or demonstration microscope. It is
constructed of lacquered brass and measures 8 inches
long when fully closed. The objective end is 3½
inches in diameter. Focusing is accomplished by push
tube. A knurled knob in the middle of the tube serves
as a locking mechanism preventing the focusing from
being disarranged as the microscope is pasted along
from student to student in the classroom. It is
equipped with a conventional ocular and an objective,
the latter is divisible for power change. The objective
end of the instrument incorporates a silvered brass
Lieberkuhn reflector, thus allowing the observation of
both transparent and opaque objects. This instrument,
although unsigned by its maker, is identical to those
made by the Berlin instrument maker Paul Waechter as
described in The Journal of the Royal Microscopical
Society, 1882 as follows:
Waechter's (or
Engell's) Class or Demonstrating
Microscope. This instrument might readily be
mistaken for an ordinary brass candlestick. Its
original form is figured by Harting (Harting, P.,
Das Mikroskop, iii, (1866) pp. 196-7) Figs. 63
and 64 show it as improved by Waechter, the lower part
being seen in Fig. 63 in section. The body-tube,
carrying eyepiece and objective, slides in an outer
"sprung" tube which is attached at its lower end to a
conical base, which forms a wide support for the
instrument to stand upon when not in actual use. The
inside of the base is polished so as to reflect light
upon opaque objects. The ends of the slides are held
beneath a metal ring at the lower end of the base, as
shown in Fig. 64, and they can be removed by turning
them round till they coincide with the two openings in
the ring. The instrument is held up to the light and
focused by sliding the inner tube in the usual way. It
can be secured at any given focus if desired by the
milled clamp ring near the top of the sprung tube. A
cover fits over the base (shown in Fig. 63) and is
pierced with a small hole to act as a diaphragm with
high powers. The instrument is intended for class
demonstration.
A similar microscope was
sold by the instrument maker and retailer James W.
Queen of Philadelphia as described and illustrated in
The Journal or the Royal Microscopical
Society, 1885 as follows:
Queen & Co.'s
Class Microscope.This (fig. 7) is identical with
Waechter's or Engell's instrument already described. We
have had one of the original forms in use for some
time, and have found it very convenient for exhibiting
objects. By daylight it is simply turned to the sky,
and there is no difficulty in at once getting the
proper illumination. By artificial light the instrument
requires somewhat more adjustment, unless there is a
large illuminating surface or the Microscope is brought
close to the source of light.
Views through the microscope