dial in the shape of a diamond, on which were marked the letters
of the alphabet, and each letter of a word was pointed out by the
movements of a pair of needles. The dial had no letter "q," and as
the man was described as a quaker the word was sent "kwaker." When
the tram arrived at Paddington he was shadowed by detectives, and
to his utter astonishment was quietly arrested in a tavern near
Cannon Street.

In Cooke and Wheatstone's early telegraph the wire travelled the
whole round of the circuit, but it was soon found that a "return"
wire in the circuit was unnecessary, since the earth itself could
take the place of it. One wire from the sending station to the
receiving station was sufficient, provided the apparatus at each
end were properly connected to the ground. This use of the earth
not only saved the expense of a return wire, but diminished the
resistance of the circuit, because the earth offered practically
no resistance.

Figure 45 is a diagram of the connections in a simple telegraph
circuit. At each of the stations there is a battery B B', an
interruptor or sending key K K'to make and break the continuity of
the circuit, a receiving instrument R R'to indicate the signal
currents by their sensible effects, and connections with ground or
"earth plates" E E' to engage the earth as a return wire. These
are usually copper plates buried in the moist subsoil or the water
pipes of a city. The line wire is commonly of iron supported on
poles, but insulated from them by earthenware "cups" or
insulators.

At the station on the left the key is in the act of SENDING a