33.
Batteries.
The dry cells used for electric bells are the most convenient batteries to
use. They can now be purchased at all prices from a shilling upwards, and
give about 1-1/2 volts when in good condition. One cell at each end will
suffice for short distances, or for considerable distances if large
conductors are used. If a single cell fails to work the buzzer strongly
through the circuit, another cell must be added.
[Illustration: FIG. 36.--Standard for sounder.]
For ease in transport it will be found advisable to mount key, buzzer, and
battery on a common baseboard, which should be provided with a cover and
handle. The three parts are interconnected with one another, and the line
wire terminals as sketched in Fig. 34. This arrangement makes the apparatus
very compact and self-contained. As a finishing touch fit the lid inside
with clips for holding a stiff-backed writing pad and pencil for the
recording of messages.
Lines.--Fencing made of stout galvanized iron wires strung on wooden
posts supplies excellent conductors for practice purposes, provided the
posts be quite dry.
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