ON THE CONSTRUCTION OF STEREOSCOPIC KALEIDOSCOPES.
If we apply the Kaleidoscope to any statue or architectural ornament,
or any other solid object represented, photographically, on a
transparent binocular slide, the figures will be combined into a
flat symmetrical pattern, as shown in a future chapter. But if, in
the lenticular stereoscope, we place a Kaleidoscope between each of
the two semi-lenses and the statue, or other object in the binocular
slide, we shall then see the statue or other object in full relief
in the symmetrical figure. This, in a rude form, is the Stereoscopic
Kaleidoscope.
In order to construct the instrument independently of the stereoscope,
we have only to combine two equal Kaleidoscopes, with their reflecting
mirrors equally inclined to each other, and place at the eye-end of
them two semi-lenses or quarter lenses, at the distance of two and a
half inches, and having their focal lengths equal to the length of the
stereoscope. If the two right and left eye photographs, to which we
apply them, are opaque, upon paper or silver plate, an opening must
be left above the object end of the reflectors, of sufficient size to
allow light to be thrown upon the photographs. When the figures are
transparent, this aperture must be closed.
If the objects in the binocular slides represent either bas-reliefs
or alto-relievos, or statues, or vases, or portions of any solid
bodies, such as animals, plants, or flowers, which can be combined into
symmetrical patterns, they will appear in their true relief in the
Stereoscopic Kaleidoscope. In this way the artist may avail himself
of the instrument in designing circular Gothic windows, the circular
decorations of ceilings, and rectilineal or curvilineal belts, that
are to be cut out of metals, marble, freestone, or wood, or formed of
plaster of Paris, or metals susceptible of fusion.[11]
[11] See my _Treatise on the Stereoscope_, Chap. xi. p. 86.
If we combine two Telescopic Kaleidoscopes, in the manner already
described, so that the centres of their object-lenses are distant two
and a half inches, and receive the right and left eye pictures of real
objects upon disks of ground glass, with the ground side touching
the ends of the reflectors, these objects, though themselves in true
relief, will be reduced to plane pictures on the ground glass, and
again brought into stereoscopic relief, and combined into symmetrical
patterns by the instrument. The effect thus produced is different from
what we should see were the ground glass removed, and the image of the
object formed in the air at the end of the reflectors, for the same
reason that the picture of an object in the stereoscope is different
from what it appears if viewed directly by the eyes.