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 polarisation 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 1000 were constructed
upon scientific principles, or were capable of giving any thing like a
correct idea of the power of his kaleidoscope.