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98 MODERN MAGIC LANTERNS.
tions it can be replaced by a slightly modified form of
compound microscope, which is attached in front of the
condenser of the usual lantern. In Fig. 72 a simple form
of compound microscope is shown, which can in a few
moments be removed from the stand on which it has served
as a table microscope and placed on the lantern nozzle,
as shown in the top right-hand figure. The objectives of
various powers can be slipped into the racked mount, those
most commonly supplied being 1- and 2-inch powers. An
additional lens as a supplementary condenser is sometimes
fitted between the chief condensers and the object,
and when properly adjusted this much improves the
illumination.
The real difficulty in lantern projection has always been
the proper illumination of the object. Lantern microscopes
cannot be expected to yield as bright images on the screen as
ordinary lanterns showing slides with but a fraction of the
magnification. In consequence, the operator's attention should
be given to the proper adjustment of the light and condensers.
The light concentrated on the small surface of the slide will
soon make it very hot unless prevented by means of an alum
trough (see p. 84) ; this in micro-projection should never be
omitted, or it will lead to the ruin of the slides.
The slides in the simpler forms of lantern microscope are
fitted in wooden frames like ordinary lantern slides, only
these frames are smaller. Frames can be obtained one end
of which takes out to receive the usual size of microscope
slide, for use in the lantern. These are a convenience, but
it is decidedly preferable to have a microscope attachment
with the usual form of plain sliding stage, so that the slides
can be used direct without any further mounting. This is
the case with the instruments shown in Figs. 72 and 73.
Too great a degree of magnification should not be attempted
until the management of the lantern with low powers has
been thoroughly mastered. A 1-inch objective will be
found the most powerful which can be used in the ordinary
way with satisfactory results, both as regards illumination
and other qualities. On changing the objective the position
of the jet should be altered until the best lighting is secured,
as it will be found that lenses of different powers require the
THE LANTERN-SPECTROSCOPE, POLARISCOPE,
ETC. 99
jet to be at different distances to yield the brightest images.
Great care must also be exercised to keep the centres of the
whole of the apparatus, jet, condensers, and objective in a
perfectly straight line. When these various points have
received attention it will be found that a large number of
objects, parts of insects, sections of wood of different kinds,
vegetable and animal tissues, etc., can be easily shown
on such a scale as to be seen well by a large roomful of
people.
A more elaborate form of lantern microscope is that
shown in Fig. 73. With this instrument far more can be
Fig. 73. DIE LANTERN MICROSCOPE.
done than that to which we have alluded, but for details
as to its manipulation larger works must be consulted.
Tiler° will always remain, however, many objects which,
from the great amount of magnification they require, or
from other causes, cannot be satisfactorily displayed in the
lantern microscope.
With such subjects the only way is to
make photo-micrographs and slides from them, showing the
latter by means of the ordinary lantern. Particulars as to
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