It can also be
applied to many polarizable objects. This quality, combined with the
transmission of a greater amount of light than is obtainable by the
polariscope, renders objects thus seen much more effective. It is
constructed as follows: Into the tube of the spot lens a short tube is
made to move freely and easily. This inner tube has a double flange, the
outer one, which is milled, for rotating, and the inner one for carrying
a glass plate. This plate is made of flat, clear glass, and upon it are
cemented by a very small quantity of balsam three pieces of colored
(stained) glass, blue, red, and green, in the proportion of about 8, 5,
and 3. The light from the lamp is allowed to pass to some extent through
the interspaces, and is by comparison a strong yellow, thus giving four
principal colors. Secondary colors are formed by a combination of the
rays in passing through the spot lens.
"The stained glass should be as rich in color and as good in quality as
possible, and a better effect is obtained by three pieces of stained
glass than by a number of small pieces. The application of the
chromatoscope is almost unlimited, as it can be used with all objectives
up to the 1/8. Transparent objects, particularly crystals which will not
polarize, diatoms, infusoria, palates of mollusks, etc.
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