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

INLAND AND EUBIVARI.VE TELEGEd-
PHIC 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 companies 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-
Cr how much they may be desired or how willingly
the money may be forthcoming for all attempts to
form them. As yet, however, notwithstanding the
popularity of the idea, there has been no great sys-
lam 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, rsndered
the transmission of messages lesslucrative than was
at first expected, and partly owing to the erest ob-
stacles which still present themselves in the way of
long sulmarine 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
so, for the improvements which it expects to intro-
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 suggest are properly and energetically
carried into effect. The error which has hitherto
proved so fatal to most plans for submarine com-
munication has been that of having a porderous
cable, weighing six or eight tons, and costing from
3001. to 500/. par 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
core, stretch, while the conducting wirds, laid
straight along the centre, cannot. In nearly every
instance, therefiere, 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 greatest
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, while the 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 out
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 S'irclinia and
Algeria. To overcome these difficulties, which
seem to offer almost_ insurmountable obstacles t
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 wen-
derfolly 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 indiarubber; coete I
over with a mixture of tar and sand. The cost of
the whole is only 701. per mile, and its weight only
Bcwt. The core 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 compens'ates 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 conducd-
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 toe 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 cable cannot be too light. In the present
instance it is so constitnted 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 ou 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 lsnd can at al!
affect the laying down of such a cable. Another
great difficulty in submarine telegraphic communi-
cation is in 'getting the electric current along a
great length of wire. Propelling a message, se to
speak, requires an intensity of electricity which at
pressnt 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 th 3 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 applicatiou
of the secondary coil, by means of which he pro-
duces an induced curren,t the great intensity of
which is almost equal to the coil of Ramkoff. 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 system
of telegraphic communication,throughout the united
kingdom almost as complete and extensive as our
present postal arrangements. It is intended to lay
down perfectly new lines, communicating direct
from London with all the chief manufacturing
• towns, which are to form sub-centres with the
mailer towns and even villages around them. The
wires will be thinly coated 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 parts of the kingdom at
one uniform rate of ls. a-messaZe, 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 ddayto each other, the
gross receipts, without . g interveningsta-
tions, would ba 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 a recording telegraph, a greAt
improvement on Moss's and Bains'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.
The ocean lines are at the ont-et to be confined
to laying a cable from the Land's end to Flores in
the Azores, and thence to Halifax, nrtking the
deep sea wretch, it is alleged, about 400 miles
shorter than the route between Newfoundland and
Ireland, and avoiding the land lines, which are ex_
pensive to maintain,
and therefore to create an