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

ELECTRIC TELEGRAPH CONDUCTORS.
CHAPTER XXXVII.
Composition of Telegraph Circuits-Conductibility of Metals and Fluids-Conducting Power of different sizes of Copper Wire-Conducting Powers of Telegraph Wires-Advantages of Zinc-Coated Wires-Conductors composing a
Voltaic Circuit-Strength of Telegraph Wires-Scale and Weight of Telegraph Wire.
COMPOSITION OF TELEGRAPH CIRCUITS.
IN the present chapter will be considered electric telegraph
conductors. There are but two questions necessary to be discussed; first, the conductibility of the metals and other materials composing the voltaic circuits; and, second, the strength
and durability of the metallic substances employed as component parts of the circuit.
Atelegraphic circuit is composed of iron wire, copper wire,
mercury, brass, tin, platina, zinc, acidulated water, and nitric
acid. This arrangement contemplates the use of the Grove
battery. The Smee, Daniell, Bunson, and other batteries, are
sufficiently near the same organization, as to conducting elements, to be considered as equivalents. In regard to the conductibility of metals there seems to be some difference of opinion.
Different experiments have produced different results.
CONDUCTIBILITY OF METALS AND FLUIDS.
Some experiments instituted by M. Becquerel produced the
results indicated in the following table. The conductibility of
each metal is given respectively.
Copper wire............. 100 Platinum wire.......... 16.4
Gold "............. 93.6 Iron..........15.5
Silver............ 73.6 Lead ".......... 8.3
Zinc "............. 28.5
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