Great Facts: A Popular History and Description of the Most Remarkable Inventions During the Present CenturyBakewell, Frederick C. (Frederick Collier)
History
Great Facts: A Popular History and Description of the Most Remarkable Inventions During the Present Century
Bakewell, Frederick C. (Frederick Collier)
Inventions
When the angle formed by the inclination of the mirrors divides the
circle into a greater number of sectors, the reflections of the images
are repeated, from points nearer and nearer to the eye, and the circle
is thus completed, however numerous the sectors may be; but at each
repetition of the reflection, the images will become more dim, since,
owing to the imperfection of reflecting surfaces, a portion of the
light is absorbed at each reflection.
In the first instruments that were constructed, the objects were
fixed in the field of view, therefore scarcely any change of pattern
was obtainable. It was not until some time afterwards that the idea
occurred to Sir David Brewster of producing endless changes of the
figures, by making the objects movable in a cell of glass at the end
of the instrument. He afterwards introduced other improvements in the
Kaleidoscope, for extending its range of objects, for varying the
angles of inclination, and for projecting the figures on a screen. In
the instrument, as ordinarily made, the objects to be seen properly
must be placed close to the end of the reflectors; but by the addition
to the instrument of a tube containing a lens, the rays from distant
objects are brought to a focus near the mirrors, and the image formed
there is repeated by the reflectors in the same manner as a solid
object.
The projection of the figures on a screen, by an apparatus similar to
a magic lantern, gives great additional pleasure to the effects of
the Kaleidoscope, as the figures are not only seen by several persons
at the same time, but they are presented in a magnified form. The
projection of the figures also increases the use of the instrument in
designing patterns, for which purpose it has been employed with great
advantage.
Public-domain text, read in full here on John Shaqi.
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