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ing behind you. Adjust the light so that the matt
screen is lit up brightly.
You can adjust the focus of the prepared slide
image using the focus knob (2). Make sure to
swivel the microscope arm (9) back into an up-
right position so that you can comfortably ob-
serve the specimen.
In a dark room, it is also possible to project the
microscope picture on a white wall. To do this, re-
move the matt screen. Swivel the tripod so that the
upper edge of the projector is horizontal. Keep
in mind that the image brightness is reduced and
the picture will be darker if the projector is far
away from the wall.
14
Experiments
Now that you're familiar with your microscope's
functions and how to prepare slides, you can
complete the following experiments and ob-
serve the results under your microscope.
Newspaper print
Objects:
1. A small piece of paper from a newspaper with
parts of a picture and some letters
2. A similar piece of paper from an illustrated
magazine:
Use your microscope at the lowest magnifi ca-
tion and make a slide preparation from each
object. Place the slide with the newspaper on
the microscope table and observe the slide. The
letters in the newspaper appear broken because
the newspaper is printed on raw, inferior paper.
Now observe the slide with the magazine prepa-
ration. Letters of the magazine appear smoother
and more complete. The picture from the news-
paper consists of many small points, which ap-
pear somewhat dirty. The pixels (raster points) of
the magazine image appear sharper.
Textile fi bres
Objects and accessories:
1. Threads of different textiles: Cotton, linen,
wool, silk, Celanese, nylon and
any others you can fi nd.
2. Two needles:
Put each thread on a glass slide and fray each
with the help of the two needles. Put a drop
of water over each thread with the pipette and
cover each with a cover glass. Adjust the mi-
croscope to a low magnifi cation. Cotton fi bres
are of plant origin and look, under the micro-
scope, like a fl at, twisted band. The fi bres are
thicker and rounder at the edges than in the
centre. Cotton fi bres consist primarily of long,
collapsed tubes. Linen fi bres are also of plant
origin; they are round and run in straight lines.
The fi bres shine like silk and exhibit numerous
swellings along the shaft of the fi bre. Silk is
of animal origin and consists of solid fi bres of
smaller diameter than the hollow vegetable fi -
bres. Each silk fi bre is smooth and even and has
the appearance of a small glass rod. Wool fi bres
are also of animal origin; the surface consists of
overlapping scales, which appear broken and
wavy. If possible, compare wool fi bres from dif-
ferent weaving mills, and note the differences in
the appearance of the fi bres. Experts can de-
termine the country of origin of wool based on
its appearance under a microscope. Celanese
is artifi cially manufactured by a long chemical
process. All Celanese fi bres show hard, dark
lines on a smooth, shining surface. The fi bres
crinkle in the same way after drying. Observe
the similarities and differences between the dif-
ferent fi bres.
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