See also:angle which is a sub-multiple of four right angles . This is the principle of the kaleidoscope, an
See also:optical toy which received its
See also:form at the hands of
See also:David Brewster about the
See also:year 1815, and which at once became exceedingly popular owing to the beauty and variety of the images and the sudden and unexpected changes from one graceful form to another . A
See also:hundred years earlier R . Bradley had employed a similar arrangement which seems to have passed into oblivion (New Improvements of Planting and Gardening, 171o) . The instrument has been extensively used by designers . In its simplest form it consists of a
See also:tube about twelve inches long containing two
See also:glass plates, extending along its whole length and inclined at an angle of 6o° . The
See also:eye-end of the tube is closed by a
See also:plate having a small hole at its centre near the intersection of the glass plates . The other end is closed by a plate of muffed glass at the distance of distinct vision, and parallel to this is fixed a plate of clear glass . In the intervening space (the
See also:object-box) are contained a number of fragments of brilliantly coloured glass, and as the tube is turned
See also:round its
See also:axis these fragments alter their positions and give rise to the various patterns . A third reflecting plate is sometimes employed, the
See also:cross-section of the three forming an equilateral triangle . Sir David Brewster modified his apparatus by moving the object-box and closing the end of the tube by a
See also:lens of
See also:short focus which forms images of distant
See also:objects at the distance of distinct vision .
These images take theplace of the coloured fragments of glass, and they are symmetrically multi-plied by the mirrors . In the polyangular kaleidoscope the angle between the mirrors can be altered at pleasure . Such
See also:instruments are occasionally found in old collections of philosophical apparatus and they have been used in
See also:order to explain to students the formation of multiple images . (C . J .
COUNT VON LEOPOLD KALCKREUTH (1855— )
DIMITRI KALERGIS (DEMETRIOS) (1803-1867)
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