Pictures By Telegraph, from Pearson’s Magazine, April 1900, describes the then-cutting-edge telediagraph, an early fax machine:
The equipment consists of two machines, almost identical in construction, the first being called the “transmitter,” the second the “receiver.” Each is provided with an eight-inch cylinder, which may be made to revolve by a delicate system of clockwork so finely regulated that both instruments work together to a nicety.Above each cylinder rests a fine platinum needle, or stylus, not unlike the point in a telegraph key. A sheet of tin-foil, six inches by eight inches, ready to wrap round the transmitter’s cylinder, and a sheet of ordinary carbon manifold-copying paper of the same dimensions, which, when placed between two sheets of blank paper, is to be wrapped round the receiver’s cylinder — these complete the chief requirements.
[...]
With a photograph of the subject before him, the artist draws its duplicate on the sheet of tin-foil, leaving a margin of about a half-inch on all sides. For this work, either pen or brush may be used; but, of first importance, the liquid must have more consistency than ink, and must be a non-conductor of electricity. An alcoholic solution of shellac is found most suitable for the purpose.
(Hat tip to Boing Boing.)