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

288 THE MAGNETO-ELECTRIC TELEGRAPH.
its advantages, and a description of the apparatus as furnished
me by Mr. Henley, one of the inventors.
Fig. 1 is a representation of Mr. Henley's instrument, as
used in the office for telegraphic service. Before giving a description of this very simple apparatus, I will present the advantages claimed for it by the inventor, which are as follows:
ADVANTAGES OF MAGNETIC OVER VOLTAIC ELECTRICITY.
1st. Capability of working without expense, except first cost.
2d. Being always ready for instant use, however long it may
have remained inactive.
3d. From its simple construction (being entirely free from
all clockwork or complicated movements, and also from all
apparatus found in other telegraphs for cutting off or reversing the electric current), it cannot get out of order.
4th. The magnetic needle used for the indications being
freely suspended on a vertical axis, without springs or weight
of any kind to keep it in the neutral position, and being subjected to the energetic action of an electro-magnet instead of
wire coils, moves with a much less electric force than any other
telegraph whatever; it, therefore, follows, from the well-known
fact of the great diminution of the power of the current in
passing through long conductors, that this telegraph will work
at a greater distance, or through a greater resistance, than any
other, the distance at which any telegraph will work through
a given sized wire being in an exact ratio with the electric
force required to work such telegraph. There have been many
ingenious contrivances made which would work beautifully in
a room, but are totally useless when practically tried between
distant stations. Another severe test of the capability of a
telegraph is a damp state of the atmosphere, especially when
the earth is used (as it always is now) as part of the circuit.
Every supporting post, when its earthenware insulators become covered with moisture, conveys a great part of the current to the earth, but from experiments tried on the South
Devon railway (known to be the worst insulated line in the
kingdom), and in the most unfavorable weather, the magnetoelectric current from this machine was found to pass the whole
distance of the line, and also through a great length of fine
wire at each station, without any loss whatever; this arises,
not from the electricity being of a different kind, but from its
quantity and intensity being so adjusted that the wet posts
should offer more resistance than the whole length of the
metallic wire. In addition to this apparatus never requiring renewal, a very important fact is the small space re