Referring to this diagram, A and B respectively represent a transmitting
and a receiving station of an automatic telegraph. These stations are
united in the usual manner by a main line, L. At the transmitting
station, A, is placed a transmitting battery, E, having its positive
pole connected by a conductor, 2, with the metallic transmitting drum,
T. The negative pole of the battery, E, is connected with the earth at G
by a conductor, 1. A metallic transmitting stylus, t, rests upon the
surface of the drum, T, and any well known or suitable mechanism may be
employed for causing an automatic transmitting pattern slip, P, to pass
between the stylus and the drum. The transmitting or pattern slip, P, is
perforated with groups of apertures of varying lengths and intervals as
required to represent the dispatch which it is desired to transmit, by
an arbitrary system of signs, such, for example, as the Morse
telegraphic code.

At the receiving station, B, is placed a recording apparatus, M, of any
suitable or well known construction. A strip of chemically prepared
paper, N, is caused to pass rapidly and uniformly between the drum, M',
and the stylus, m, of this instrument in a well known manner. The drum,
M', is connected with the earth by conductors, 4 and 3, between which is
placed the auxiliary battery, E, the positive or marking pole of this
battery being connected with the drum and the negative pole with the
earth. The electro-motive force of the battery, E', is preferably made
about one-third as great as that of the battery, E.

[Illustration]

Extending from a point, o, in the main line, near the transmitting
station, to the earth at G, is a branch conductor, l, containing an
adjustable artificial resistance, R. A similar conductor, ll, extends