IMPROVEMENTS IN TESTING AND WORKING SUBMARINE ELECTRIC TELEGRAPH WIRES
Year: 1865

page_text: LETTERS PATENT to Willoughby. Smith, of the Gutta Percha Works,
Wharf Road, in the County of Middlesex, Electrical Engineer, for the
Invention of "IMPROVEMENTS IN TESTING AND WORKING SUBMARINE
ELECTRIC TELEGRAPH WIRES."
Sealed the 24th April 1866, and dated the 26th October 1865.
PROVISIONAL SPECIFICATION left by the said Willoughby Smith at the.
Office of the Commissioners of Patents, with his Petition, on the 26th
October 1865.
WILLOUGHBY SMITH, of the Gutta Percha Works, Wharf Road, in the
County of Middlesex, Electrical Engineer, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN TESTING AND WORKING SUBMARINE
ELECTRIC TELEGRAPH WIRIS," to be as follows:-
My Invention consists in the arrangements hereafter described, whereby'
during the laying of the submarine telegraph a constant insulation test and
communications from the ship to the shore and from the shore to the ship may
be maintained, and whereby the telegraph wires may be worked after the
laying thereof. On board the ship I place the cable in communication with
a galvanometer, and this galvanometer with a battery with a wire going to
[Price 8d.1

page_text: earth as has been already done, and consequently this part of the arrangement
forms no part of my Invention. I connect the shore end of the cable with a
resistance apparatus connected with a galvanometer which is in communica-
tion with the earth. I also employ and apply by means of a key to the shore
end a current from one of two resistance coils or condensers of different power
for the purpose of speaking to the ship. For speaking from the ship to the
shore reversed currents are transmitted from the ship.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Willoughby-Smith in the Great Seal Patent Office on the
26th April 1866. [Title amended by order of the Lord Chancellor, 2nd
May 1866.]
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLOUGHBY
SMITH, of the Gutta Percha Works, Wharf Road, in the County of Middlesex,
Electrical Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-sixth day of October, in the year of our
Lord One thousand eight hundred and sixty-five, in the twenty-ninth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Willoughby Smith, Her special licence that I, the said Willoughby
Smith, my executors, administrators, and assigns, or such others as I, the
said Willoughby Smith, my executors, administrators, and assigns, should at
any time agree with, and no others, from time to time and at all times
thereafter during the term therein expressed, should and lawfully might
make, use, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for "In
PROVEMENTS IN TESTING AND WORKING SUBMARINE ELECTRIC TELEGRAPH WIRES,"
upon the condition (amongst others) that I, the said Willoughby Smith,
my executors or administrators, by an instrument in writing under my,
or their, or one of their hands and seals, should particularly describe and
ascertain the nature of the said Invention, and in what manner the same was
to be performed, and cause the same to be filed in the Great Seal Patent
Office within six calendar months next and immediately after the date of the
said Letters Patent.
NOW KNOW YE, that I, the said Willoughby Smith, do hereby declare
the nature of my said Invention, and in what manner the same is to be

page_text: performed, to be particularly described and ascertained in' and by the
following statement thereof, reference being had to the Drawings hereunto
annexed, that is to say :-
While submerging electric telegraph cables it has hitherto been the practice
to devote certain portions of each hour to the different electrical tests which
it has been considered necessary to make; for instance, during the laying of
the Atlantic cable the hour was divided into four parts, and a certain test had
to be repeated every hour at the time allotted to it. In this instance the first
thirtyminutes wereoccupied on shipboard in testing theinsulation or resistance
of the gutta percha, as shewn in Figure 1 of the accompanying Diagrams, in
which C represents the cable; G, the galvanometer; and B, the battery. The
other thirty minutes were divided into three equal parts, which were devoted
respectively to receiving reversals from the shore, ascertaining the resistance
of the conductor, and sending reversals to the shore; these tests are respec-
tively represented in Figures 2, 3, and 4. The most important tests, and the
only tests which are absolutely necessary during the submerging of a cable,
are those for insulation and for the continuity of the conductor. A ready
means of immediate communication between the ship and the shore is always
desirable. Hitherto each test has been applied independently, that is to say,
while the continuity test was being made the insulation has had to be
neglected, and vice versa. Consequently in the arrangements above men-
tioned the state of the insulation of the cable was not known during the last
thirty minutes of each hour. The danger attending the intermittent discon-
tinuance of this test during one half the time occupied in laying the cable is
evident, as it should be perpetually maintained.
Now the primary object of this Invention is to enable the electrician in
charge of a submarine electric telegraph cable, more especially while it is
being submerged, to keep up a constant test for insulation and continuity,
and at the same time to communicate freely through the cable between the
ship and the shore.
Before proceeding to explain the manner in which I carry my Invention
into effect, I may remark, in order to assist in explaining my Invention, that
were it possible for a submarine electric cable with the water surrounding it
to be placed in an insulated trough, not only could the resistance of the
dielectric enveloping the conductor be arrived at by measuring the amount of
current passing into the cable after a certain time has been allowed for
electrification (which constitutes the ordinary insulation test), but also by
merely placing a wire from one terminal of a galvanometer in connection
with the water, and a similar wire in connection with the other terminal to'

page_text: earth, the actual amount of current passing out of the cable through the
dielectric could be measured, and thus tests could be made by two separate
persons quite independently of each other. Although such an arrangement
as that just described is impracticable as regards the entire cable there would
be no difficulty in placing a few miles of the coil at one end of a cable under
the conditions explained, and these would be sufficient for the purpose of my
Invention. But I attain my object in a much more convenient and cheaper
. way. I construct and employ a resistance apparatus, which may be varied so
as to equal that of the dielectric of any length of the cable. While taking an
ordinary insulation test the distant end of the electric conductor has to be
insulated, or isolated from all surrounding conductors, as shewn in Figure 1.
Now to carry out my Invention I attach an insulated plate or a series of
plates of
any good conducting material to the free end of the conductor, and
between such plates I place a thin sheet or sheets of a material of com-
paratively high electric resistance, paper or dry wood saturated with an
insulating material or gelatine in thin sheets answers the purpose. Suppose
I employ a series of six metal plates, then each alternate plate is connected
to the conductor of the cable, and the remaining three are connected
with the earth through a galvanometer. Consequently'the amount of current
which passes through the material placed between the copper plates flows
through the galvanometer to earth, and thus a constant deflection is registered
as long as the line is kept charged at a uniform tension. But if the tension
should alter, or the direction of the current be reversed, the change in the
deflection is immediately noticed, and by this means the person in charge of
the batteries, by a pre-arranged code of signals, communicates with the
person in charge of the galvanometer without interfering with the insulation
test. Thus, if it is arranged to work with the Morse code, the deflection to
the right hand may be used to represent the dot, and the deflection to the
left hand, caused by reversing the current, may represent the dash; or the
same code may be worked readily by altering the tension, and thus causing
high or low deflection, which may be considered as representing dots and
dashes. This latter method has an advantage over the former, inasmuch as
the cable can always be charged from the copper end of the battery, which is
most desirable in long submarine lines. To enable the person in charge of
the distant galvanometer to communicate with the battery station a resistance,
which in this case I prefer to be made of very fine silk-covered wire (by
preference, German silver wire) has one of its ends attached to the stud of an
ordinary contact key, and the other end to earth, the conductor of the cable
being in contact with the key. Therefore when the key is pressed down to

page_text: the stud a portion of the current from the charged cable passes through the
resistance coil to earth, thus causing an increased deflection on the galva-
nometer at the battery station. By varying the amount of resistance, or the
duration of the contact, deflections representing dots and dashes can be
produced. Where I have indicated the employment of resistance, condensers
may in each instance be substituted, and in this case every alteration in the
tension, or the reversal of the current, will cause a very sudden and strong
deflection on the distant galvanometer. This being an inductive effect the
deflection will be in proportion to the size of the condenser.
While laying a
submarine telegraph cable the batteries and testing apparatus should be on
board the cable ship. On shore the end of the conductor of the cable should
be joined to a resistance which allows only sufficient current to pass to give a
distinct reading on a much more sensitive galvanometer than that used on the
ship. In fact the leakage through the resistance should be such as in no
way to interfere with the insulation test. The resistance used on shore for
the continuity test should be of sufficient magnitude to make it impos-
sible to increase the deflection on the ship galvanometer beyond a certain
limit.
The working of this system will be fully understood on reference to
Figure 5, which represents an arrangement of apparatus suitable for carrying
my Invention into effect; G is the ship galvanometer; B and B' are batteries
of the same tension, but so connected to keys K and K' that the cable can
be conveniently charged from either the copper of the one or the zinc of the
other; R is a resistance attached to the shore end of the conductor and the
galvanometer G, the other terminal of this galvanometer being connected to
the earth; and are resistances which can be brought into contact with
the conductor at will by means of the key K". The galvanometers G
and G. are by preference mirror-reflecting galvanometers. Suppose the'
cable to be charged from the battery B, by pressing the key K, after, say one
minute's electrification, the reading on the galvanometer G will be, say 50
divisions, and that on the galvanometer G', 130 divisions. The resistance R
may be disconnected and reconnected repeatedly, without in any way altering
the reading of the galvanometer G. If the key K" be brought into contact with
the resistance 7, for say the fifth part of a second, the deflection on the
galvanometer G will be increased, and by regulating the time of contact the
image, can be placed at, any desired part of the scale, or letters may be
substituted for the figures on the scale, and thus a very quick and simple
system of telegraphing will be obtained. Reversals may be employed to
reverse the deflection on the galvanometer. G¹. Communication between the

page_text: two instruments is thus complete without in any way interfering with the
insulation test. When charging with reversals, to alter the deflection on the
galvanometer G', it is best to place a shunt on the galvanometer G, in case
the full charge should injure that instrument.
Figure 6 represents a set of apparatus arranged according to my system
for working through the cable after the same has been laid; C represents the
cable; Rand R'are resistances, with respective galvanometers Gand G'attached'
in connection with the conductor of the cable; keys K and K' (connected
to batteries B and B' respectively by one of their studs) are also attached to
the conductor. The remaining studs of the keys are respectively connected
to artificial cables A and A¹, the inductive capacity and resistance of which
can be altered at will. The galvanometers H, H', and N, N', have letters or
other convenient signs placed in the range of their respective magnets, or in
the range of the image from the same, if mirror galvanometers are used.
Suppose a cable to be laid between England and America, and the arrange-
ments to be at each station, as represented in Figure 6. To communicate
with England, the operator in America charges the cable by pressing the key
K down on the stud connected with the battery B, which causes an immediate
deflection on the galvanometer G' in England, and the operator there at
once connects his battery to the line by means of the key K¹, and is thus
ready to receive. As soon as the increased deflection on the galvanometer
at the American station shows that the call has been noticed the operator
there releases the key K from the batteries and proceeds as follows:-By
pressing the key K down to the stud in connection with A a small
portion of the current leaves the cable and passes through the galvanometer
H to earth. The increase of the deflections on the galvanometers H and N
are in proportion to the length of time allowed for contact. Consequently if
the instruments H and N' are properly adjusted, it follows that if the contact
is maintained until the magnet or image points to the desired letter on the
scale of the galvanometer H, the same letter will be indicated on the
galvanometer N' at the distant station. Thus any alphabet or code can be
employed with certainty and comparative rapidity, and the line nevercharged
except from the copper plate of the battery.
And having now described the nature of my said Invention, and in what
manner the same is to be performed, I declare that I claim,-
First, the arrangement, substantially as herein-before described, whereby
during the laying of submarine electric telegraph wires a constant insulation
and continuity test and free and unbroken communication between the ship
and the shore may be maintained.

page_text: Second, the arrangement, substantially as herein-before described, whereby
submarine electric telegraph wires may be worked after the laying thereof.
In witness whereof, I, the said Willoughby Smith, have hereunto set
my hand and seal, the Twenty-fifth day of April, One thousand eight
hundred and sixty-six.
WILLOUGHBY SMITH. (L.B.)