BY W. J. GORDON.
The kaleidoscope is the most successful scientific toy of modern times.
Immediately after its patenting by Sir David Brewster over three hundred
thousand were sold in three months. Essentially it consists of a couple
of mirrors arranged at an angle forming some even sub-multiple of three
hundred and sixty. The angle usually chosen is the sixth, or sixty
degrees.
Before proceeding to make a kaleidoscope for home use, it would be well
to try a few experiments with two common pieces of looking-glass.
Arrange them as in the diagram (Fig. 1), and placing an object at A, or
standing them on a piece of colour work, notice the beautiful
geometrical pattern formed by the various reflectors. Having
experimented with various articles at the angle given, try the effect at
another angle, and note how the slightest change affects the design.
Having grasped the general principle you can proceed to make one of the
commoner varieties of the instrument as usually sold. These have three
mirrors.
[Illustration: Fig. 1.]
[Illustration: Fig. 2.]
[Illustration: Fig. 3.]
Cut three pieces of common glass into the shape here given. Let them be
seven and a half inches long, one inch and five-eighths wide at A, and
one inch wide at B (Fig. 2). If they are silvered on the back so much
the better; if they are not, paint them black on one side. A very good
black paint for the purpose is made by mixing vegetable black with gold
size until it is as thick as cream. Seven-pennyworth of gold size and a
pennyworth of vegetable black, obtained from the nearest oil-shop, will
give you enough paint for a dozen kaleidoscopes, and be useful for other
purposes into the bargain. The three mirrors are to be arranged in a
tube, with their blackened sides outwards (see Fig. 3); and the tube is
to be made accordingly. An old copy-book cover can be rolled into the
shape, or a well-pasted strip of newspaper rolled round and round on a
stick, as described in the chapter on the telescope, will give the tube
with very little trouble. To fit the mirrors we have cut the tube should
be eight and a quarter inches long, two inches in diameter at the broad
end, and one inch and an eighth in diameter at the narrow. Of course the
tube is not absolutely necessary; a square box two inches wide and eight
inches and a quarter long will answer every purpose, but then the
mirrors, instead of being kept in position by the sides of the case,
will have to be wedged up by pieces of cork or balls of paper.
[Illustration: Fig. 4.]
Having made the case, fix an eyepiece of tin or cardboard at one end, so
that a hole a quarter of an inch in diameter comes in the centre of the
angle made by the mirrors. This hole is shown in position in Fig. 4,
which represents the top of the tube or box.
At the other end of the tube a round piece of clear glass is to be
fixed, and if the box is used a square piece will take its place. The
round can be easily made from the square by chipping off the corners. An
American glass-cutter, costing sixpence, can be obtained from most
tool-shops, which will be found very useful in cutting glass for this
and many other purposes. The secret in working wheel glass-cutters of
all kinds is to keep the handle as nearly upright as possible and to
bear firmly and equally on all parts of the work.
Having cut the plain glass end and fitted it close up against the broad
end of the mirrors, the next thing is to cut a piece of ground-glass of
the same size to fit over it. This ground-glass may be patterned, as in
the kaleidoscopes of commerce. It is, however, more satisfactory to have
it plain. Between the glasses you place the pieces of broken glass to
form the designs.
‘The objects which give the finest outlines by inversion are those which
have a curvilinear form, such as circles, ellipses, looped curves like
the figure 8, curves like the figure 3 and the letter S; spirals and
other forms, such as squares, rectangles, and triangles, may be applied
with advantage. Glass, both spun and twisted, and of all colours and
shades of colours, should be formed into the preceding shapes; and when
these are mixed with pieces of flat coloured glass, blue vitriol, native
sulphur, yellow ochre, and differently coloured fluids, enclosed and
moving in small vessels of glass, they will make the finest transparent
objects for the kaleidoscope. When the objects are to be laid upon a
mirror plate, fragments of opaquely-coloured glass should be added to
the transparent fragments, along with pieces of brass wire, of coloured
foils, and grains of spelter. In selecting transparent objects, the
greatest care must be taken to reject fragments of opaque glass, and
dark colours that do not transmit much light; and all the pieces of spun
glass, or coloured plates, should be as thin as possible.’
As far as the harmony of colour is concerned, it may be as well to note
that the deepest red harmonises with an equal mixture of blue and green;
that red goes best with green and blue, the blue being predominant; that
orange-red requires a blue with a good deal of indigo; that
orange-yellow wants pure indigo; that light yellow is best with violet
and indigo half and half; that greenish-yellow shows off best by the
side of pale violet; that green goes with a full violet; that
greenish-blue combines with violet and red; blue with orange and red;
indigo with orange-yellow; and violet with green.
Satisfactory effects can, however, be produced with almost anything
bright and shining. The first kaleidoscope we, in the thirst for
knowledge, took apart was found to have for its objects about forty
pieces of red, green, blue, and brown stained glass, smashed up into
irregular fragments of about a quarter of an inch in width and length,
and as the shapes were varied and the colours crude, the patterns at
every shake were almost as startling as those produced by a sixpenny
catharine-wheel on the 5th of November.
The ground glass should be fitted into a cap, so as to be removable at
pleasure, and the fragments of coloured glass to form the patterns
should be left free to move between the glasses.
Having made this kaleidoscope, and coaxed it into acting properly,
experiments with other contrivances should be made. Mirrors should be
arranged at ninety, forty-five, and forty-five; at ninety, sixty, and
thirty, and other angular combinations. A lens should be fitted at the
end of the tube for magnifying purposes, and the tube should be attached
to a magic lantern, and the patterns, almost equalling the chromatrope,
thrown on the screen.
[Illustration: Fig. 5.]
Having worked the fixed mirrors to the point of weariness, shifting
mirrors should be tried, and then two mirrors, made to alter their
angles by an arrangement of screws (see Fig. 5), as in the adjustable
form of the instrument, should be experimented with.
You will soon find that when the inclination of the mirrors is not an
aliquot part of 360 the reflections will not join, and then the
following table from Sir David Brewster’s manual of the kaleidoscope may
prove useful:--
No. of No. of No. of Direct
Inclination. Reflections. Pictures. Pictures.
120 3 2 1
72 5 2 3
51-3/7 7 4 3
40 9 4 5
32-8/11 11 6 5
27-9/13 13 6 7
24 15 8 7
21-3/17 17 8 9
18-18/19 19 10 9
17-1/7 21 10 11