The New York herald., 1922-04-23
IT WE EAT AND WEAR GUARDED BY USEFUL, MICROSCOPE

showing the amoeba, paramoeciun,,
stentor and also the diminutive but
majestic navicula with its mysterious
propelling force. all in motion in the
water in which they live.
A microscope is made with sliding
frame for comparing two or more
samples: another form shows a di-
vided field in which the samples APP
pear side by side for inspection. Other
instruments have spectroscope at
tached, by means of which the merest
trace ,f chemical clements exhibits
their characteristic lines upon the
spectrum.
Various attachments are made for
microscopes. some for utility. others
for producing spectacular effects. A
small mirror or prism is used to re-
fleet the microscopical image toward
the surface OF a sheet of drawing
paper, where outline drawings may be
made with ease and comfort. The
projection microscope is used like n
stereopticon. except that actual speci-
mems may be shown on the screen in
stead OF lantern slides.
With the projection microscope and
polariscopic attachment minerals in
thin sections, parts or insects and
various other objects may be shown
on the screen greatly enlarged. and
with the addition of gorgeous colors
produced by the prisms in tie polari-
scope, by selenite screens and by their
own retroactive properties.
Another interesting attachment for
the microscope is called the dark field
iliuminator. This exhibits the speci-
mems brilliantly shining. on a black
ground. Advantage is taken OF this
method in viewing ultramicroscopical
particles. those too small to be ac-
tually seen. but which are demon
strable by the light which they reflect
through the microscope to the eye. A
homely illustration of this phenome-
non is the beam Of light in a darkened
room, in which particles of dust too
small to be seen are visible as tiny
points of light reflected from their
surfaces
a Lost Art Reborn by
Use of Microscope
A recent development in micro
scopy comes as a revival of lost art.
Years ago the ruling Of fine lines on
glass with which to test the magnify
ing power of lenses was accomplished
by clever constructors OF precision
| machinery. Then other machines were
devised, by means of which writing
was done on glass with very finely
pointed diamond chips. The space oc-
cupied by the writing was so small
as to appear to the naked eye like a
point of light on smooth piece Of
glass. Under the microscope the writ
ing could be deciphered as easily as
one reads the page of a book, A mod
ern microscopic uses the same ap-
paratus and method to send messages
to his friends.
During the Franco Prussian war
messages were photographed on slips
of paper by the reverse of magnifica-
ton, the result being a micro photo
graph Of infinitesimal size. but ex-
hibiting under the microscope per-
fectly legible writing or printing. In
| the recent war this method was again
used. and as the messages could be
rolled up into very small space car.
rier pigeons easily transported them
| to their destinations.
/, Space forbids extended considera
ton of other important uses of mod
ern microscopes. but mention should
be made OF their great aid TO the in
vestigator in the field of agriculture.
Life histories of insect pests AID the
causes of crop failures due to mildew,
rust and kindred fungous diseases of
plants are all studied with the micro
scope. and remedies found that add
millions of dollars to the farmers in
] comes and to the country's welfare.