The telegraph manual: a complete history and description of the semaphoric, electric and magnetic telegraphs of Europe, Asia, Africa, and America, ancient and modern.

BAIN S DESCRIPTION AND CLAIMS OF HIS INVENTION. 363
roller, which fits into the transmitting machine, so that the
communication is ready to be passed through that machine.
In regard to the preparation of this paper for the application
of the apparatus, the following will serve as explanatory:
To receive a communication, the wire brush is to be
turned back to the right by means of the pointer, to be out
of contact with the transmitting roller; then take a piece of
fine, good smooth paper, the width of which should be equal to
the length of the cylinder, and long enough to go round the
cylinder, with the ends lapping over each other a quarter of an
inch; this paper is to be previously prepared as follows: It is
to be laid on any clean surface that acids will not act on, the
paper is then to be covered on the upper surface with oil, by a
very clean sponge; for this good salad oil will answer, but
other oils will answer, if they do not evaporate too quickly,
because the use of the oil is to lessen the evaporation of the
chemicals next noticed, by retaining their moisture; the paper
is then to be turned over, and washed with a clean sponge containing a solution of nitric acid, prussiate of potash, and liquid
ammonia, in the following proportions-the ammonia is merely
added to prevent the other ingredients from rotting the paper:
Two parts, by measure, of pure nitric acid, twenty parts, by
measure, of a saturated solution of prussiate of potash, in distilled water, and two parts of pure liquid ammonia, mixed
together. The paper so prepared is to be laid, with the oiled
surface upward, on and around the cylinder, and the lapping
edges fastened with a little gum water; the cylinder is then to
be put in place, and the steel slide is to be turned on to the
paper; the apparatus is then ready to receive a transmitted
communication. The machinery is then to be worked by a
man at the wheel, at the rate of one revolution of the wheel
per minute, the same as in transmitting a communication, and
as before stated. The operator at any one distant station
transmits the electric current in pulsations, regulated by the
perforations in the paper he is using, as already explained, and
these pulsations are received by the wire, as before mentioned,
they pass by the screw and standards, axle, thence to the stem,
and through that to the style, and through the chemically prepared paper to the cylinder, leaving a dark mark on the paper,
which, though less in size, will be in number and position an
exact transcript of the perforations in the paper used at the
transmitting station. It is proper to notice, that steel styles
leave a dark mark approaching black or blue black on the paper,
but copper styles will leave a brown mark on the paper. It is
not intended to discuss the theory of the causes that produce