The kaleidoscope : $b its history, theory and construction. With its application to the fine and useful artsBrewster, David
Science
The kaleidoscope : $b its history, theory and construction. With its application to the fine and useful arts
Brewster, David
Kaleidoscopes
The effect produced by the combination of three reflectors at angles
of 90°, 45°, and 45°, is shown in Fig. 47. The two reflectors =A O=,
=A B= produce a pattern =C D B I=, composed of eight triangles; the
reflectors =B O=, =B A=, likewise give a pattern =A F G H=, composed of
eight triangles; and the reflectors =A O=, =O B=, give a pattern =A B H
I=, composed of four triangles. The triangle =I H K= is an image formed
by three reflexions, one half of it being a reflexion of half of =A I
_a_=, from the mirror =B O=, and the other half a reflexion of half of
=B H _b_=, from the mirror =A O=; and the triangle =D E F= consists of
two half images, which are reflexions of the two half images in =I O
H=. The remaining triangle =D L F= is a reflexion of =I K H=, from the
mirror =A B=, and is therefore formed by four reflexions.
As the three mirrors are not symmetrically placed, with regard to each
other, the equally luminous images are not arranged symmetrically
round the open triangle =A O B=, as in the preceding combinations.
The effect is, however, very pleasing, and all the reflected images
included in the figure =C L G K= are sufficiently bright.
5. _On combinations of three reflectors at angles of 90°, 60°, and 30°._
[Illustration: FIG. 48.]
The most complicated combinations of three reflectors is represented
in Fig. 48. In the first combination, all the angles were equal; in
the second, two of the angles only were equal; but in the present
combination, none of them are equal. The field of view, represented in
the figure by =D E H L M P=, is a truncated rhomb, consisting of no
fewer than _thirty-one_ images of the aperture =A O B=. The figure is
composed of two hexagons =D E F B R C=, =R B K L M N=, every division
of the hexagon consisting of two reflected images, and of two rhombs =C
R N P=, =F B K H=, each of which is composed of four reflected images.
In this combination, as in the last, the equally luminous sectors
are not symmetrically arranged round the centre =O= of the figure.
In the rhomb =C R N P=, for example, the four images are formed by
three, four, and five reflexions; whereas in the corresponding rhomb
=F H K B=, they are formed by two, three, and four reflexions. The
effects produced by a Kaleidoscope constructed in this manner are very
beautiful, particularly when the reflectors are metallic. In the four
figures which represent the different combinations of the reflectors,
the small figures indicate the number of reflexions by which each image
is produced.
CHAPTER XIV.
ON KALEIDOSCOPES IN WHICH THE EFFECT IS PRODUCED BY
TOTAL REFLEXION FROM THE INTERIOR SURFACES OF
TRANSPARENT SOLIDS.
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