IMPROVE- MENTS IN THE MANUFACTURE AND MODE OF LAYING DOWN SUBMARINE ELECTRO- TELEGRAPHIC CABLES
Year: 1861

page_text: PROVISIONAL SPECIFICATION left by George Clark at the Office of
the Commissioners of Patents, with his Petition, on the 25th Februarý
1861.
I, GEORGE CLARK, of No. 11, Nicholl Square, in the City of London,
Gentleman, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN THE MANUFACTURE AND MODE OF LAYING DOWN SUBMARINE ELECTRO-
TELEGRAPHIC CABLES," to be as follows:-
The object of this Invention is to prevent the loss of the whole or part of a
submarine telegraphic cable when submerged by the breaking or slipping of
the cable as it is paid out. This kind of accident, which experience has
proved to be of frequent occurrence, has become a serious hindrance to the
success of trans-oceanic telegraphy, in consequence of the enormous amount
of capital absolutely sacrificed by the cable being irrevocably lost at the bottom
of the sea. As a well known example it is sufficient to refer to the fate of
the transatlantic cable, of which the value of the capital lost is more than
three hundred thousand pounds. One cannot help being struck with amaze-
ment at the reckless folly displayed by the persons who had the mangement
and control of the operation. There is not, perhaps, an instance on record of
such a stupendous destruction of property in a moment of time, for when the
cable snapped, ceased to transmit the electric current, the loss of more than
a quarter of a million was consummated. It seems incomprehensible that no
means were devised by the accumulated science, talent, and practical skill
brought to bear on the project, to guard against so terrible a disaster by dividing
the risk. The danger of breaking a wire rope not thicker than a man's

page_text: finger in paying out hundreds of miles into ocean depths varying from 50
fathoms to two miles, from a ship of two thousand to three thousand tons
burthen, tossed by the Atlantic billows and exposed to heaving, pitching, and
rolling in stormy weather, is so great and palpable that to immerse a cable
extending in one line from Ireland to America, without the occurrence of an
accident would be a miracle, and certainly if the proposition is put in that
simple form it does look like madness to attempt the feat when the penalty,
in case of failure, is of such stupendous magnitude.
The obvious remedy for this obstacle to sub-oceanic telegraphy is to divide
the risk by securing communication with sections of the cable as successively
laid down, and reducing the loss in case of accident to the maximum quantity
of one section at a time.
My Invention which has that object in view I will now proceed to describe.
To the electric cable intended to be laid down I propose to affix at given
distances from each other, electric branch cables which I call safety branches,
made on the same plan as the main cable, and of at least the same, or
perhaps greater, thickness and strength, an arrangement which, as I will
herein-after explain, may, under certain circumstances, be desirable. These
branches will be connected with the main cable at a suitable 'angle by means
of a spliced joint through which the metallic continuity of the electric wires
will be carried to each branch and along the main.
Figure No. 1 is the Diagram of a branch (a) connected with the main (b);
No. 2 is a branch joint piece disconnected at the joint (c), of which the
section (d) shows the mode of maintaining the metallic circuit in both
directions.

page_text: the branch, securing at the same time the metallic continuity in both directions,
and the perfect insulation of each of the wires, as well as solidity of con-
struction:
For the practical application of the Invention I propose that the safety
branch cables be connected to the main at given distances of several miles from
branch to branch, and each branch will be of a length corresponding to, and
somewhat exceeding the known depth of the ocean, previously ascertained by
soundings at the intended points of immersion of the branches. The branches
may be attached to the main as it is manufactured, or as it is stowed away in
the ship from which the cable is to be passed into the sea, or the branch joints
may be incorporated with the main when manufactured, leaving short branch
ends, 10 or 20 feet, or more, protruding, as shewn in Figure No. 1, to
which, as the main is run out and these ends come up, branches of the
required length may be spliced, but this will cause delay. Every branch will
be laid down with the main on the coils or drums from which the latter is
to be paid out. As the cable is run out the end of the branch will present
itself, and will be immediately seized hold of and handed over to a steam
tender, No. 1, alongside, which will proceed at the same speed as the ship
until the branch has run off the coil to the joint, when the tender will imme-
diately lie to and remain stationary until the next section of the main cable is
run off and made safe by its branch cable being secured to tender No. 2, with
which, when the end of another branch presents itself, the same operation will
be repeated, and tender No. 2 in its turn, in like manner with the former, will
lie to until another section of the main is run out. As soon as tender No. 2
is in position with its branch cable out and secured, it will pass the signal
"all right" along the wires to tender No. 1, which on receiving the signal
will cast off its branch (insulated at the end) into the sea, and proceed at full
speed to overtake the ship and repeat the same operation as before. When it
has secured a third branch it will signal tender No. 2 to cast off and come
forward, thus each branch in turn will represent an end of the cable secured"

page_text: above water ready to be made use of as a part of the main should an accident
occur to the section which is being submerged. In the event of such an
occurrence the ship would make all speed back to the tender to which the last
branch was secured, and the end of the branch being spliced to the end of the
main, the operation of paying out, after letting down a new safety branch,
would recommence. Under this arrangement not more than the broken part
of one section of the main could be lost at a time, and even that loss might be
recovered if it were thought advisable to underlay the broken section by
hauling up by means of the branch. The advisability of recovering the broken
section or abandoning it would depend upon the state of the weather and other
circumstances; if fine, and the depth of the sea not too great, the former
course might be adopted, and if stormy and the soundings unfavorable, the
latter. The risk of breakage during the underlaying process must be taken
into account, for if that accident should occur the whole length of cable run
out would be lost, therefore as a rule it might be more prudent to abandon the
broken section. By employing three tenders two branches might be kept
above water at a time, which would afford greater security. If the broken
section be left in the sea the loss of electricity by leakage through the naked
ends of the broken wires under water will have to be considered. The effect
can be tested and determined, and if any serious loss of electrical
power should
ensue it will be for electricians to discover a remedy or a palliative; but it
seems probable that oxidation of the metal and adhesion of marine substances
to the end of the wires will in time cause complete insulation and prevent any
leakage or diversion of the electrical current.
To carry out the operation successfully three tenders would be required,
and to prevent delay the tenders must be able to steam at a speed double that
of the ship in paying out the cable, so that each tender in its turn after casting
off a branch may get alongside the ship in time to take up another branch. If
the lost section of the main cable were underlayed and recovered there would
be no loss of electricity from the broken ends of wires, and if that process of
recovering could be resorted to with certainty of success, branch cables which
were not electrical media of continuity with the main might be made use of
simply by connecting them with the main previously to stowing the cable on
board the ship, or at the time of lowering the branch overboard.
My Invention therefore divides itself into two parts, 1st, the use of branches
in the way described, being metallic media of electrical continuity with the
main; or, 2nd, merely branch cables or hawsers attached to the main at given
distances, and lowered into the sea for the purpose of being used to haul in
and recover a broken section of the main. Whichever of these plans is had

page_text: recourse to, the branch ought to be of greater strength than the main, in order
to bear the strain of hauling up the broken section, but I am inclined to think
that the abandonment of the broken section when the electrical safety branch
plan is applied will be found in practice to be the best plan, for altho' it
involves the loss of a portion of the cable, that loss will probably be preferable
to the risk and expence of underlaying and recovering the broken section, an
operation which necessarily will cause great loss of time, a precious element in
laying down ocean telegraphic cables.