The Sun.
London, England, 1857-04-09 00:00:00

INLAND AND SUBMARINE TELEGRA-

PHIL COMMUNICATION.

The attention of all speculators, both on this and
the other side of the Atlantic, has of late been,
much directed to this important subject. The
gigantic undertakings of recent cempantea and the
gigantic failures which have signalised the efforts
of others have left the public mind in a state of
some uncertainty as to the practicability of great
ocean lines of telegraphic communication, no mat-
in- how much they may be desired or how willingly
the money may be forthcoming for all attempts to
form them. As yet, however, notwithstarrling the
popularity of the idea, there has been no great sys-
tem of telegraphs devised, especially such as obtain
in the United States. This has been in part owing
to the expense, which, by inducing extra charges,
has, of course, by reducing the number, rendered
the transmission of rne=sages less lucrative than was
at first expected, and partly owing to the great ob-
stacles which still present themselves in the way of
long siihmarine cables. A scheme, however, is in
progress of being organised, which at least pro-
mises to meet all desiderata, to bring the means of
inland communication to the doors of all in the
united kingdom, and to fathom with its submarine
lines the broadest and most distant seas. Whether
the proposed plan will answer or not we cannot
say, though, if properly carried out, it ought to do
sr,, for the improvements which it expects to intros
duce into the means of telegraphing are not less
important than the changes it proposes to effect in
the system itself. These mechanical aids and in-
ventions are the patents of Mr. Allan, who has de-
voted himself with untiring energy to perfecting
the electric telegraph—to the development of
which he has applied practically some of
the more important recent discoveries of
our chief electricians. These improvements
consist, first, in essential mechanical alterations in-
troduced into the construction of submarine cables,,
next in various new apparatus for the appl cation'
to the telegraph of Faraday's most valuable disco-
veries in -voltaic electric induction. On both points
the gain to the public should be great if the inven-
tions and the further improvements which they' will
naturally august are properly and energetically
carried into effect. The error which has hitherto
proved so fatal to most plans for subinarine com-
munication has been that of having a ponderous
cable, weighing six or eight tons, and costing from
3001. tb 5001. per mile. These cables, as our read-
ers are aware, are composed by winding spirally
eight or ten stout iron wires round a soft core of
gutta-percha, which contains the insulated conduct-
ing wires of copper, laid straight. In attempting
to lay down such lines in deep waters their weight
is so enormous that they can only be prevented
• sinking in a mass by powerful breaks on the drum
on which they are coiled, and which, when they
act at all, strain the cable to such an extent that
the outside spiral wires, working upon the soft
cote, stretch, while the conducting wires, laid
straight along the centre, cannot. In nearly every
instance, therefore, in which Weight cables have
been laid down in deep seas, either some of the
conducting wires have been severed entirely, or
when the strain and. pressure have been greatesi;
their insulation has been injured, or they have be-
come attenuated. The first two accidents of course
utterly destroy the whole cable as a medium for
telegraphic communication, whilethe last is scarcely
less injurious, as in all conductors of electricity the
weakest part becomes the standard of the whole,
aid the difficulty already experienced in getting a
full-sized wire to conduct a current sufficient to
transmit a message along 1,000 miles of submarine
cable would, of course, be increased almost indefi-
nitely with a wire reduced by strain in any part to
halt its original diameter. Almost all these acci-
dents have occurred in attempts to lay long
lines of cable under deep seas. This was espe-
cially the case with the Mediterranean cable,
which, from its 'preposterous weight, ran oat
so fast that no breaks were sufficiently powerful to
check it, though in the attempt to do so the con-
ducting wires were crushed, and "kinks" occurred
so rapidly that in a very short distance all of them
were severed, and it was at last found necessary to
abandon the cable altogether. So with the cable
in the Gulf of St. Lawrence, and so with the second
cable in the Mediterranean, between Ssrdinia and
Algeria. To overcome these difficulties, which
seem. to offer almost insurmountable obstacles to
any long line of submarine. communication, Mr.
Allan has invented a new kind of cable, which,
when once seen, is, like breaking the egg, a won-
derfully simple solution of the present difficulties.
It is a cable about one inch in diameter, the centre
of which is formed by 19 wires, of tinned-iron wire,
twisted into one strand, an inch in circumference.
This is enclosed in a case of indiartibber, coated
over with a mixture of tar and sand. The cost of
the whole is, only 701. per mile, and its weight only
Bcwt. The corn of this cable is thus made both its
strength and its conductor. The conducting power
of iron as compared with copper is as 24 to 120,
but the' increased sectional !area afforded by the
large iron strand more than compensates for the
relative difference. But under certain circum-
stances the strand may be formed of iron and copper
mixed, combining the enhanced conductibility of
the copper with the strength of the iron, so that
where weight to carry or much increased conduc i-
bility is a minor consideration the amount of metal
and insulation may be subdivided, and so form
several conductors without at all diminishing its
strength, as a whole. They can be made on this
principle of iron and copper mixed, and so as with-
out mixing the metals in each conductor they will
be formed of conductors of different metals. The
lightness and comparative smallness of this cable
make it appear but a slender thread by which to join
distant climes, sundered by the roll of the great
waters of the Atlantic and Pacific Oceans; but expe-
rience has shown that within certain limits as to dura-
bility the cahle cannot be too light. In the present
instance it is so constituted as to have a relatively
greater specific gravity to the water, and no more
than is required for the purpose of submerging itself
gradually. Thus, without the use of damaging breaks
on the drum, it may be laid lengthwise on the sur-
face, finding its way to the bottom in that position,
it requiring all its weight and the friction in the
water for the last few hundred yards to produce
force sufficient to withdraw it from the ship. No
depth of water or distance from land can at all
affect the laying down of such a cable. Another
great difficulty in submarine telegraphic communi-
cate:en is in getting the electric current along a
great length of wire. Propelling a message, so to
speak, requires an intensity of electricity which at
present cannot be produced without quantity, and
which in long distances charges the conducting
wire and produces a retarding influence, the pro-
per means to overcome which are to this hour an
enigma among the most profound electricians.
If we are rightly informed, there are both land
and submarine wires going comparatively short dis-
tances from the metropolis, to send a message
through which requires battery power to an extent
that is perfectly amazing, and even then in damp
or unfavourable weather the needle moves most
sluggishly. It is still almost doubtful whether this
retarding influence, in whatever manner it is caused,
may not prove a fatal obstacle to any submarine
cable between this country and America. Mr.
Allan meets this- difficulty by a novel application
of the secondary coil, by means of which lie pro-
duces an induced curren,t the great intensity of
which is almost equal to the coil of Rumkoff. The
result of the experiments that have been as yet tried
with this apparatus have been in the highest degree
satisfactory. The only doubt that exists in our
mind is that, in case of only one wire being laid, as
with the newly contrived cable, the water must be
used for the return current, which supposes a per-
fection of insulation in the conducting wire such
as, for a distance of 2,000 or 3,000 miles, it will
be difficult, and indeed almost impossible, to attain.
But we presume the subject of a return wire to
complete the circuit will be a matter for the subse-
quent consideration of the company. It is proposed
by the company that is about to avail itself of these
patents to establish, in the first 'instance, a sysetn
of telegraphic communicationthroughout the united
kingdom almost as complete and extensive as our
present postal arrangements. It is intended to lay
down perfeetly new lines, communicating direct
from Loudon with all the chief manufacturing
towns, which are to form sub-centres with the
smaller towns and even villages around them. The
wires will be thinlyeoated in gutta-percha, and
laid in numbers branching off to the different towns
en route. The cost of each wire, it is estimated, will
not exceed 101. per mile. It is intended by these
to convey messages to all parti of the kingdom at
one uniform rate of ls. a-message, or a penny
a-word irrespective of distance. This principle has
answered well in the United States and Switzer-
land, where it is found that the revenue of the tele-
graph developes itself in geometrical progression ac-
cording to the number of towns included by it.
Thus, if 12 of the largest towns in England send on
an average 50 messages per day to each other, the
gross receipts, without including intervening sta-
tions, would be 120,4501., while 24 towns sending
100 messages per day would yield nearly 500,000/.
per annum. For carrying out this system Mr.
Allan has devised aa great
recording telegraph,
improvement on Moss's and Baths's, which, while
avoiding the mistakes which in spite of the utmost
care so often occur with the needle telegraph, can
be worked at less than half its cost.
Tire ocean lines are at the outset to be confined
to laying a cable front the Land's end to Flores in
the Azores, and thence to Halifax, making the
deep sea stretch, it is alleged, about 400 miles
shorter than the route between Newfeundlaud and
Ireland, and avoiding the land lines, Which are ex-
pensive to maintain, and therefore to create au