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

VOLTAIC CIRCUIT GENERATING APPARATUS. 3
that of the wire would be, as has been fully established by
experiments made here with the experimental telegraph.
" The second portion of the conducting chain leads from the
Royal Academy to my house and observatory in Lark-street.
This conductor is of iron wire, and both the to and from wires
are 6,000 feet long, and are stretched over steeples and other high
buildings, as has already been described.
" The third portion of the chain or conducting wires runs
through the interior of the buildings, connected with the Royal
Academy, and thence to the mechanical workshop attached to
the cabinet of natural philosophy. This is a fine copper wire,
and 1,000 feet long. It is let in the joinings of the floor, and
in part imbedded in the walls.' The foregoing three different ranges or lines of wire, the first
of copper, the second of iron, and the third of fine copper, in the
aggregate near seven and a half miles of wire, run from and
return to the same place, and to which, in whole or singly, may
be attached the apparatus for generating the electric current,
and for indicating the communication transmitted."
APPARATUS FOR GENERATING THE VOLTAIC CURRENT;
Hydro-eleefricity, or that current which is generated by the
voltaic pile, is by no means fitted for traversing very long conducting wires, because the resistance in the voltaic pile, even
when many hundred pairs of plates are employed, would be
always inconsiderable, compared with the resistance offered by
the wire itself.
The principal disadvantage, however, attendant on the use of
the pile or trough apparatus, is the fluctuation of the current,
joined to the circumstance of its becoming very soon quite
powerless, and requiring to be t taken to pieces and put together
again. The extremely ingenious arrangement of Morse is
likewise subject to this inconvenience. All this, however, is
got over, when one, to generate the current, has recourse to
Faraday's important discovery of induction,' that is to say, by
moving magnets placed in the neighborhood or close to the
conducting wires. The better way, however, is not to move
the magnets, as Pixii does, in his electro-magnetic apparatus,
but rather to give motion to the multipliers placed close to a
fixed magnet. The arrangement that Clarke has given to the
multiplier, is the one which, with some modifications, has been
adopted. Assuming, on the part of the'reader, a general
knowledge of the principles of the apparatus, these explanations