A method of working telegraph lines. When a signal is sent the line is
charged. This has to be got rid of, and is an element of retardation. In
double curb working it is disposed of by sending a momentary current
first in the reverse, and then in the same, and finally in the reverse
direction. This is found to reduce the charge to a very low point.

In duplex telegraphy the sending of two independent messages from the
same end of the line in the same direction.

A variety of duplex telegraphy in which the messages are sent from
opposite ends of the line, simultaneously, so as to be transmitted in
opposite directions. (See Working, Diplex.)

In multiplex telegraphy the transmission of two messages,
simultaneously, over one wire. (See Telegraphy, Multiple.)

The volt-coulomb, q. v., or watt-second, as it is often termed.

When a force acts upon a body and the body moves in the direction of the
force, the force does work. Hence, work is the action of a force through
space against resistance.

It is generally expressed in compound units of length and weight, as
foot-pounds, meaning a pound raised one foot.

A galvanometer or other instrument used for identifying the ends of a
given wire in a cable containing several.

A method of winding disc and drum armatures. It consists in advancing
the commutator ends of the U shaped turns progressively, so that as many
commutator bars intervene between any two consecutive commutator
connections of the wire as there are leads of wire on the drum between
consecutive leads of the wire. This is carried out with due regard to
the principle that taking the letter U as the diagrammatical
representation of a turn of wire, its two members must move through
regions of the field of opposite polarity.

A method of dynamo or motor-armature winding. A single groove passes
longitudinally around the core and in this the wire is continuously
wound. The system is not now used. The old Siemens’ H armature
illustrates the principle.

A method of winding a generator or motor. Each commutator-brush has two
connections. One set are the terminals of the outer circuit, the other
set are the terminals of the field-magnet windings. In other words, the
field-magnet windings are in shunt or in parallel with the outer
circuit.