The Press.
London, England, 1857-10-31 00:00:00

1066

battery. The crest of the pendulum lifts the one of these
springs which it touches off the pillar for the time. When
it lifts the right spring, it sends a current from the positive
pole out through it and the wire, and back through the left
spring to the negative pole or pillar. When it
touches the left spring, it sends a current out through
it and the wire the opposite way, and back through
the right spring to the negative pole or pillar. The wire is
coiled in different places round bars of soft iron. When the
current passes through these coils, the bars become mag-
nets for the time, but the precise nature of thar magnetism
depends on the direotion in which the currents run.
• • • • •

Having thus 1,146 miles of telegraphic cable under their
hands and this delicate piece of scrutinising apparatus to
work with in making investigations, the first fact to be
determined by the experimenters was, could any avail-
able signal be transmitted through the 1,146 miles of con-
ductor. A seconds pendulum was first arranged to turn on
the electrical current to the wire at each beat without
attempting the reversal of the current. A trace appeared
in a very short time under a style connected with the
further end of the cable ; there could be no doubt of the
ability of the electrical influence to make itself telegraphi-
cally manifest through that vast extent at least.
There was, however, this curious anomaly in the result
of the experiment. The pendulum made connection with
the voltaic battery only for an instant at each beat ; but
the printed trace on the paper was not interrupted. It was
one long continuous line. The reason for this was, that
the conducting wire did not discharge itself between beat and
beat. The current moved so sluggishly and unwillingly
in this protracted and indnction•encumbered channel,
that one transmission was not able to clear itself oft, before
the next was pressing upon its heels, and in confusion
with it.
Nut discouraged even by this result, the ex-
perimenters persevered, and their patience
and ingenuity were rewarded by the discovery
that, by sending rapid alternations of different
kinds of electricity along the wire, seven, and
even eight, currents readily recorded them-
selves distinctly in a second.
So soon as this point was satisfactorily
settled, the question arose, of what weight and
size must be the Atlantic wire ? The reasons
for adopting the particular size chosen for a
conductor are not clearly stated. The results
of two hundred experiments proved, we are
told, that—
Wire of increased capacity did not transmit electrical
signals with greater facility and speed than the smaller
one. With a length of 166 miles, the velocity of movement
of the simple voltaic current came out •16 of a second for a
single wire; •21 of a second for a double one ; and .28 for
a treble one. With the same length, the velocity of the
double induction current came out for the single wire, .08;
with the double one, lig ; and with the treble one, .005 of
a second. With a length of '250 miles, the velocity was for
voltaic electricity, .29 and *406 of a second for a single and
double wire respectively, and fur the double induction
current, '145 and 'lB5 of a second. The fact thus actually
is, that increasing the size of the conductor augments
retardation in the trantimissicn of electricity through it.
A treble-sized conductor gives nearly a doubled rate of
retardation.
Why not, then, use a much smaller conductor?
That would have been the logical course to
pursue, had the experimenters been convinced
that the law here stated is correct.
In the autumn of last year, so much had
been settled that it only remained to actually
record a signal through two thousand miles
of circuit. Accordingly—
On the night of the 9th of October, 1838, the conclave
of experimenters met at the offices of the Magnetic Tele-
graph Company, in old Broad-street, Loudon, and the
hours of ordinary repose were spent in carrying out the
investigation which had been planned. The result was an
unquestionable triumph. Ten gutta.percha covered
insulated wires, each measuring more than 200 miles,
were connected, so that one continuous circuit of above
2,000 miles was formed, the coils of fine wires introduced
for experimental purposes at the joints of the wires further
increasing the circuit virtually to the amount of 2,300
miles. The magneto-electric induction coils of Mr.
Whitehouse were used to excite the wires, and the current
was made to operate by means of receiving apparatus, upon
one of l'rofessor Morse's ordinary recording instruments.
Signals were distinctly and satisfactorily telegraphed
through the two thousand miles of wire at the rate of 210,
241, and upon one occasion 21'0 per minute. No more
emphatic expression of the importance of th-.. result of
this experiment could perhaps be given, than the simple
statement of the impression which was made upon the
mind of the highly qualified and experienced American
investigator, who was present as a witness. Shortly after
the trial, Professor Morse wrote to the distinguished friend
and advocate of Atlantic telegraphy, Mr. Cyrus Field, in
tha following words :—" There can be no question but
that, with a cable containing a single conducting wire of a
a ze not exceeding that through which we worked, and
with equal insulation, it would be easy to telegraph from
Ireland to Newfoundland, at a speed of at least from eight
to ten words per minute. Take it at ten words in the
minute, and allowing ten words for name and address, we
can safely calculate upon the transmission of a twenty
words' message in three minutes. Twenty such messages
in the hour ; four hundred and eighty in the twenty-four
hours; or fourteen thousand four hundred words per day.
Such are the capabilities of a single•wire cable, fairly and