A jet of water, passing through a hole in a brass plate fixed at the end
of a glass tube will emit a musical sound, in consequence of the
intermittent flow of the liquid through the orifice. Again, a slender
vein of water, some twelve inches long, on being allowed to fall
vertically from a vessel, will break at the lower end of the vein into
drops. This vein of water should be brightly illuminated from above by a
beam of light sent through it from an electric lamp, so that the thread
of water will look like a line of light, from the end where it breaks
into drops to the orifice from which it issued. A musical note of
constantly-increasing pitch being then set up by means of the wind
instrument known as a “syren,” when the note reaches a sufficiently high
pitch, the sound will act upon the luminous column of water, which will
shorten itself by four or five inches, in response to the one particular
sound to which it was sensitive. The same jet of water will respond to
the beats produced by two organ-pipes, &c.