The idea of this instrument, constructed for the purpose of creating and
exhibiting a variety of beautiful and perfectly symmetrical forms, first
occurred to Sir David Brewster in 1814, when he was engaged in
experiments on the polarization of light, by successive reflections
between plates of glass. The reflectors were, in some instances,
inclined to each other; and he had occasion to remark the circular
arrangement of the images of a candle round a centre, or the
multiplication of the sectors formed by the extremities of the glass
plates. In repeating, at a subsequent period, the experiments of M. Biot
on the action of fluids upon light, Sir David Brewster placed the fluids
in a trough, formed by two plates of glass, cemented together at an
angle; and the eye being necessarily placed at one end, some of the
cement, which had been pressed through between the plates, appeared to
be arranged into a regular figure. The remarkable symmetry which it
presented led to Dr. Brewster's investigation of the cause of this
phenomenon; and in so doing, he discovered the leading principles of the
kaleidoscope.
By the advice of his friends, Dr. Brewster took out a patent for his
invention; in the specification of which he describes the kaleidoscope
in two different forms. The instrument, however, having been shown to
several opticians in London, became known before he could avail himself
of his patent; and, being simple in principle, it was at once largely
manufactured. It is calculated that not less than 200,000 kaleidoscopes
were sold in three months in London and Paris; though, out of this
number, Dr. Brewster says, not, perhaps, one thousand were constructed
upon scientific principles, or were capable of giving anything like a
correct idea of the power of his kaleidoscope.
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