CHAPTER IX.

The electrical kite--Candles magically lighted--St. Elmo’s
fire--The chronoscope--The electric clock--The electric
telegraph--Sub-marine telegraphs--The overruling providence of
God.


In the auto-biographical memoirs of sir John Barrow, lately published,
he says, when describing some of the employments of his youth: “I had
fallen in with an account of Benjamin Franklin’s electrical kite, and a
kite being a very common object with school-boys, and a string steeped
in salt-water with a glass-handle to it not difficult to be had, I
speedily flew my kite, and obtained abundance of sparks (like those
obtained from an electrical machine). An old woman, curious to see
what I was about, was too tempting an opportunity to not to give her a
shock, which so frightened her, that she spread abroad in the village
that I was no better than I should be, for that I was drawing down fire
from heaven. The alarm ran through the village, and my poor mother
entreated me to lay aside my kite.”

It was recently announced by a professor of magic, that several hundred
candles would be lighted by one pistol shot. Accordingly, the stage
appeared in partial darkness, but, through the gloom, ranges of candles
might be indistinctly perceived at different heights from the floor;
and, in a minute or two, the performer was seen to enter and discharge
a pistol, when all the candles were instantly ignited, and the array
of magical instruments appeared strongly illuminated, ready to be
employed in the subsequent exploits--an effect always followed by
enthusiastic acclamations. And yet there is no difficulty in explaining
this prodigy. Candles, carefully prepared to ignite readily, might have
above them an arrangement of wires, with the point of a wire just over
each wick, and the whole being connected with an electrical battery,
they could be ignited instantly, at a moment’s notice. The instant of
the performer’s entering, might be the signal for the discharge of the
battery by others, and the report of the pistol would prevent any sound
being heard on the removal of the wires, which the previous darkness
had effectually concealed.

Lord Napier says, that when he was in the Mediterranean, some years
ago, and during an awful thunderstorm, he was retiring to rest, when
he heard suddenly a cry, from those aloft, of “St. Elmo and St. Anne!”
which induced him again to go on deck. On observing the appearance of
the masts, the maintop-gallant-mast-head was completely enveloped in
a blaze of pale phosphoric light; the other mast-heads presented a
similar appearance; the flame preserving its intensity for eight or
ten minutes, and then gradually becoming fainter. Yet this appearance,
which superstition declared to be miraculous, was only electrical; for,
while the solar heat is converting into vapour the water and moisture
of the earth, electricity is freely disengaged. “The clouds which
this power forms are in different electrical conditions, though the
electricity of the atmosphere, when serene, is invariably the same.
Hence the descent of clouds towards the earth, their mutual approach,
the force of atmospherical currents, and the ever-varying agencies of
heat and cold convert the aërial envelope of the globe into a complete
electrical apparatus; spontaneously exhibiting, in a variety of forms,
the play of the conflict of its antagonist powers. At the close of
a sultry day, and above level plains, the opposite electricities of
the earth and the air effect their re-union in noiseless flashes of
lightning, illuminating, as it were, in far-spread sheets, the whole
circuit of the horizon, and the entire canopy of the clouds. At other
times, the same elements light up the arctic constellations with their
restless wildfires--now diffusing their phosphoric flame, and flitting
around in fitful gleams, and now shooting up their auroral columns,
advancing, retreating, and contending, as if in mimicry of mortal
strife.”[I]

That electricity and magnetism are identical, is evident from many
experiments. If a sewing-needle be placed in a wire, twisted in that
form called a helix, and a shock of electricity be then passed through
it, from a Leyden jar, the needle will be magnetized. The form of the
wire, and the manner of placing the needle, are shown in the figure.

[Illustration]

[Illustration]

Again, if M be a piece of soft iron, of a horse-shoe shape, and
surrounded with copper-wire covered with a non-conducting substance, it
will become powerfully magnetic on connecting the ends of the wire with
a galvanic battery. If this be only of a moderate size, and a keeper,
I, be attached to M, it will suspend W, representing a very heavy
weight.

Mr. Barlow has so arranged a globe, as to identify the dip of the
needle with electricity, a current of which appears to be always
passing round the earth. At G, in the opposite diagram, is a globe
having a wire covered with silk, coiled entirely over it, from one
pole, round and round to the other. The ends of this wire dip into two
cups, P and N, connected with the poles of a galvanic battery. When the
current passes from this, the small and delicately balanced magnets,
_m_, will show polarity, and dip, just the same as in the earth itself.

[Illustration]

Mr. Bain’s electric clock is a remarkable contrivance. Nothing can be
more satisfactory or complete. Allowing for wear and tear of materials
from friction, and the oxidating influence of the atmosphere, the
perpetual motion appears to be realized. As long as the electricity
of the earth continues, or, in other words, as long as the laws of
nature last, so long will Mr. Bain’s clock continue its oscillations,
and register the transit of time. The pendulum conducts, and is the
treasury of that power, and two simple wheels and their attachments,
with the dead escapement, complete the machine. By an ingenious
provision, Mr. Bain’s electric clock at the manufactory extinguishes
the gas-light which illuminates its dial, at half-past twelve precisely.

Mr. Bain has invented and patented another kind of electric clock,
the clock being in Glasgow, and the pendulum in Edinburgh. By means
of the electric telegraph along the railway, constructed by Mr. Bain,
he intimated his wish that the pendulum at the other end of the line
should be put in motion. The clock was placed in the station-house
in Glasgow, the pendulum belonging to it in the station-house at
Edinburgh, the two being forty-six miles apart. They were joined by
means of the wire of the telegraph, in such a manner as that, by a
current of electricity, the machinery of the clock in Glasgow was
made to move correctly, according to the vibrations of the electrical
pendulum in Edinburgh. Thus, in like manner, were England and Scotland
united in one great chronometrical alliance, a single electrical
pendulum of this description, placed in the Observatory at Greenwich,
would give the astronomical time correctly throughout the country.

[Illustration]

The electric telegraph may be said to have originated in a trivial
incident. It occurred to professor Oersted, of Copenhagen, to try the
effect of a galvanic current on the needle of the compass. He found it,
on making the experiment, deflected, that is, turned aside from its
usual bearing of due north and south. Professor Wheatstone applied this
result very ingeniously. He arranged a series of needles, mounted like
that of the compass, and found that he could turn any of these aside by
galvanic currents, while the others remained at rest. It was evident,
therefore, that if each needle were supposed to denote a letter, any
letters might thus be indicated; and, consequently, if an arrangement
of needles standing for so many letters, respectively, were placed
at the distance of fifty or a hundred miles, and any of them were
acted on by means of wires traversing the distance, a message could be
despatched at one end of the line, and read off at the other from the
deflected needles, by any person duly acquainted with the arrangement.
A similar set of needles at the opposite end, would enable him, as
certainly, to transmit a reply.

The engraving represents the front of the telegraph, exhibiting the
index, as it is denominated. The wires, which are suspended through
the length of the line, are attached at either end to the telegraphic
instruments, a branch wire being fastened to a large metallic surface,
imbedded in the earth for completing the electric current. When at
rest, the handles are down, and the pointers remain in their vertical
position. The signals are given by two magnetic needles, or pointers,
each suspended vertically on an axis passing through the dial, and,
behind, another pointer is fixed on each corresponding axis. A portion
of the conducting wire, many yards in length, is coiled round the
galvanometer frame, in which the magnet moves, so as to subject the
magnet to the multiplied deflecting force of the electric current.

[Illustration]

The battery is the motive power of the machine, occupying the same
relative position to it, as the boiler does to the locomotive; for,
though it does not produce any immediate result on the works, yet the