AN IMPROVED SUBMARINE HYDRO-ELECTRIC TELEGRAPH CABLE."
Year: 1870

page_text: LETTERS PATENT to Ferdinand Tommasi, of Paris, Boulevard de
Strasbourg, No. 23, for the Invention of "AN IMPROVED SUBMARINE
HYDRO-ELECTRIC TELEGRAPH CABLE."
PROVISIONAL SPECIFICATION left by the said Ferdinand Tommasi
at the Office of the Commissioners of Patents, with his Petition,
on the 6th July 1870.
I, FERDINAND TOMMASI, of Paris, Boulevard de Strasbourg, No. 23,
do hereby declare the nature of the said Invention for "AN IMPROVED
SUBMARINE HYDRO-ELECTRIC TELEGRAPH CABLE," to be as follows:-
The object of my Invention is a system of hydro-electric cable
applicable for submarine purposes, which is based upon the transmission
of pressure by liquids.
My cable is composed of one or several pipes of copper or other
convenient material equal in number to that of the despatches it may be

page_text: mercury is sufficient to cause in one direction or another the alternate
establishment or rupture of the current; from whence the progress in
ordinary telegraphic machines by utilising each raising and lowering of
the lever in order to cause the ordinary escape wheel of these apparatus
to advance one tooth. The transmission of pressure by this system is
nearly instantaneous for two hundred movements, or more may be
communicated in one minute; and this instant communication always
exists whatever may be the distance separating the manipulating
apparatus from the receiving apparatus, for the transmission is entirely
independent of the length of tube.
The necessary conditions for enabling the hydro-electric cable to act
regularly are the following :--
1st. The manipulating apparatus must be placed at the same level as
the receiving apparatus, which may easily be done by observing the
level of the water.
2ndly. The cylinder, the pipes in the cable, and the glass tube must
be made of sufficiently rigid material to be able to support without
straining or giving way in the slightest degree under the pressure which
must be exerted upon the liquid thread before mentioned in order to
obtain the displacement of the mercury. The lever must also be so
rigid as not to bend.
3rdly. The water must so exactly fill the cylinder, the pipe in the
cable, and the glass tube that no air bubble may possibly exist therein
and produce an elasticity injurious to the transmission.
4thly. The quantity of water contained in the cable must always be
the same, notwithstanding the increase or diminution of volume which
the changes of temperature or the undulation of the cable may
produce.
The two latter conditions may be fulfilled in a variety of ways by
taking the necessary precautions when laying the cable; but I proceed
to indicate the means I prefer.
t
Each pipe of which the cable is to be composed is rolled around a
drum, and very carefully filled with distilled water; the two cocks at
each of its ends respectively communicating with the receiving and
manipulating apparatus. All the pipes so filled and intended for the
same cable are brought together in a so-called mattress of tarred hemp
covered as already stated; this cable is stored on the ship intended for

page_text: '
laying it, taking care that in the ship the open cocks of the pipes are
plunged into reservoirs full of water until they are put into relation with
the various apparatus. When the cable is all on board ship the cocks of
the ends plunged in water are closed, and those ends withdrawn; one
of the ends of the pipe intended to send despatches is screwed upon a
pipe of the apparatus, and another pipe is put into communication with
a reservoir of water, the level of which is superior to the edge of the
cylinder, the piston is drawn back, the various cocks are opened, and the
water is allowed to penetrate until it overflows from the cylinder; the
piston is then introduced into the cylinder and pressed into its position;
the lever is restored to its position, and the cock closed; one of the
pipes intended for receiving despatches is then screwed upon the pipe of
the receiving apparatus, the pipe is put into communication with a
reservoir of water the height of which is the same as the upper end of
the glass tube, in which there is no mercury; the cocks upon the
receiving apparatus are opened, and another cock is opened, so that the
pipe is in communication with the glass tube and with the other tube;
one cock is closed, and the other turned so that the pipe is no longer in
communication with the glass tube or the pipe just mentioned. The
immersion is then made in the manner known.
The two ends of each
If an imperative necessity compels the cable to be cut the ends are
closed with a particular collar, plug, and screws.
pipe are at the proper time united and soldered.
cable has reached its destination the ends of the pipes are fastened, as
has been described above.
When the end of the
This cable may, if desired, be kept down in deep waters by means of
DECIFICATION
шец m pursuance of the Conditions O the Letters
Patent, and of an Order of the Lord Chancellor, by the said
Ferdinand Tommasi in the Great Seal Patent Office on the 6th
February 1871.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, FERDINAND
TOMMASI, of Paris, Boulevard de Strasbourg, No. 23, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent bearing date the Sixth day of July, in the year of our

page_text: Lord One thousand eight hundred and seventy, in the thirty-fourth
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said Ferdinand Tommasi, Her special licence that
I, the said Ferdinand Tommasi, my executors, administrators, and
assigns, or such others as I, the said Ferdinand Tommasi, my execu-
tors, 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 "AN IMPROVED
SUBMARINE HYDRO-ELECTRIC TELEGRAPH CABLE," upon the condition (amongst
others) that I, the said Ferdinand Tommasi, my executors or adminis-
trators, 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 per-
formed, and cause the same to be filed in the Great Seal Patent Office
within seven calendar months next and immediately after the date of
the said Letters Patent.
NOW KNOW YE, that I, the said Ferdinand Tommasi, do hereby
declare the nature of my said Invention, and in what manner the same is
to be performed, to be particularly described and ascertained in and by
the following statement, reference being had to the Drawings hereunto
annexed, that is to say :-
If a tube of any given length filled with a thread of liquid and
provided at its extremities with two moveable pistons, the tubular
extremities through which these pistons move being of equal diameter
and above all the two pistons of equal calibre. Let us suppose that this
tube being conveniently bent and the two extremities united one with
the other and the two pistons connected between them by an oscillating
lever common to both and rendered solid, so that the same operator may by
acting at once on the two oscillating extremities of the lever cause one.
of the pistons to descend and at the same moment cause the other to rise..
Let us suppose further (and this condition is essential), that previously
to the action of the lever a pressure which can always be given from
the outside and arbitrarily to have compressed the liquid and the surface
of the tube to the extreme limit, that is to say, to such a degree that
the incompressibility of the liquid on the one hand and unalterability
of form and interior capacity of the tube on the other hand may be

page_text: ascertained by experiment within the limits of action to give to the lever.
All matters being so arranged experiment will show that (a.) not only
the effort exerted upon one of the pistons will be immediately com-
municated to the whole mass of liquid contained within the tube and
to the other piston. But also (and this is what follows from the in-
compressibility and unalterability previously assumed) (b.), so much
liquid space will be left under the first piston put in movement as will
occupy a similar space under the second; (c.), as to the rapidity of the
effects to produce it may be varied according to the wish of the operator
in proportion to the power of action of which he will dispose as much
by himself as by any other auxiliary force.
My hydro-electric cable is only an entirely natural application from the
above premises. It is in principle a tube filled with liquid and acting
in the conditions above laid down. The two first of these conditions
are the practical execution and simple adjustment. As to the third
(concerning the unalterability of volume and the capacity of the liquid.
and of the tube) independently of the force of compression which can
be given at any previous time in order to obtain it, it is necessary to
take the following precautions, the fulfilment of which guarantees both.
the exact action of the apparatus and the duration of the important
element, the cable itself. The conditions are:-
First. To completely fill the pipe with a liquid incapable of producing
oxidation or incrustation therein.
Secondly. To manage so that the liquid can in no case suffer cither
augmentation or diminution of volume. And now,-
:-
How can this liquid thread by the effect of its displacement
act upon electric telegraphic apparatus? This is what I proceed to
describe The hydro-electric cable is composed of any desired number
of small pipes of pure copper coated with mastic, minium, or other
suitable substance and bound together in cork which unites them firmly.
These bundles are themselves covered over and strongly bound by a
solid covering of tarred hemp and wire. The diameter of the cable and the
proportions of the different matters composing it should be calculated,
so that its weight does not exceed about 18 lbs. troy for each pipe per
mile, the weight of an equal volume of sea water. As many despatches
to be sent or received simultaneously require as many couples of pipes,
or what is the same thing, as many doubled pipes in the cable.

page_text: Figures 1 and 2 represent the elevation and section of a cable con- :
taining four pipes and fitted consequently for the simultaneous expedition
or reception of two despatches..
Figure 3 represents an interrupting or relay apparatus. The
cylinder A with its screw piston and the pipes B and H are of
polished iron. The two glass tubes C'and C¹, which each contain a
platinum thread G. of unequal length, one end of which proceeds out
through the swelling I to which it is soldered, are firmly cemented in
the said iron pipes and in the copper pipes K.. The solidity of this
arrangement is ensured by screws turning upon vertical steel rods. The
screw. piston A¹ allows at will to rise or descend in the glass tubes the'
mercury contained in the cylinder A and in the tubes B and H. The
two platinum threads are each in relation with a thumbscrew fixed upon
the socket of the apparatus..
Figure 4 represents an apparatus of simple manipulation (I call this
apparatus "the simple manipulator" to distinguish it from the electro-
magnetic manipulator, which may replace it as will presently be men-
tioned) Figure 5: a regulating press. From merely looking at these
two Figures their purpose will be readily understood. As many pipes
as there are in the cable require an equal number of interrupters and
manipulators. As many couples of tubes require an equal number
of regulating presses..
Figures 6 and 7 show a system in which four tubes are employed with
the necessary apparatus for maintaining the cable in. working order.
It should be well understood that during the putting together the
cocks E,. Figure 7,.which terminate the little pipes already previously
filled with water,. should be constantly closed, and that its interrupters
should not yet contain: mercury..
In order to put the system into practice the pistons of all the
cylinders of the manipulators are drawn back, as well as of all the
cylinders of the interrupters; all the washers F are unscrewed, all the
union pieces G. and G, are put into communication with a pump, all the
cocks are opened, and distilled water is injected by means of the pumps.
When water flows through the cylinders C, C¹, and A¹ (Figure 7),.
the pistons are returned to their first position, when it proceeds through.
all the cocks Gʻ and H¹ they are closed, and when it has arrived at the
upper ends of the pipes K the cocks E, No. 2, are closed, the piston of
the cylinder A', No. 2, is drawn back, mercury is poured therein, the
י,

page_text: said piston is returned to its place, the level of the mercury in the glass
tubes No. 2 is made to rise up to 0.039 inches from the lower end of
the platinum wire (tube C¹, Figure 3,) the lower end of the other wire
plunging into the mercury in consequence of the inequality of length.
The cocks E, No. 2, are opened, the pipes K, No. 1, filled with
distilled water, the washers F, No. 1 and 2 are screwed on, the cocks
M and M², No. 2 are closed, the cock N, No. 2 is left open, and the
thumbscrews of the interrupter No. 2 are put into communication with
the pile of the receiving apparatus.) On the other side the cock N, No. 2,
is closed, the cocks M and M³, No. 1, are left open, the cock D, No. 1 is
closed, and the handle D (Figure 4) of the manipulator, No. 1 is pressed
by the hand. If the quickness with which this movement is transmitted
to the mercury contained in the interrupter No. 2 is less than it is desired
to obtain, the cock D, No. 1 is opened, a certain quantity of water is
injected by means of the pump H, No. 1, at the same time the weight Cni
of the regulating press No. 1 is gradually augmented, so that the piston
of the said press finds itself midway in its course; the cock D, No. 1, is
closed, the quickness of the transmission is again tested, and so on as
many times as may be necessary to obtain the quickness desired; the
cocks M and E, No. 1, are then closed, the washers F, No. 1, are
unscrewed, the pistons of the cylinder A¹, No. 1, are drawn, and mercury
is poured therein; this piston is then thrown back to its place, the level
of the mercury is caused to rise in the glass tubes No. 1 up to within
0.039 inches of the lower end of the platinum wire, (tube C³, Figure .,)
the lower end of the other wire plunging on the contrary into the
mercury, in consequence of the inequality of length above mentioned.
The pipes K, No. 1, are then filled with distilled water, the washers F,
No. 1, are screwed up, the cocks M and E, No. 1, are opened, and the
thumbscrews of the interrupter No. 1 are put into communication with
the pile and receiving apparatus intended to play the role of the con-
troller. One then operates precisely in the same manner upon the pipes
and the apparatus No. 3 and 4. Care should be taken never to open
the cock D (Figure 5) before having screwed the nut H (Figure 4), and
to never unscrew it before having closed the said cock. This precaution
is indispensable to avoid the pressure upwards exercised by the water in
the cylinder C when the cock D (Figure 5) is open, from raising the
piston C¹ (Figure 4) at the moment when its duty is to be lowered.
The course of the pistons may be modified by raising or lowering the
centre of rotation of the beam F (Figure 4), so that the displacement of

page_text: course.
the mercury in the glass tubes does not overpass 0.039 inches from its
It is now easy to understand what passes in the liquid thread,
either when the handle D is pressed by the hand, or when pressure is
removed therefrom, and in what manner the displacement of the liquid
thread acting upon the electric telegraphic apparatus take place. The
pipes No. 1 and 2 in consequence of their connection with the in-
terrupters Nos. 1 and 2, only form in reality one pipe containing a
liquid thread, in which the mercury plays simply the part of index. The
unalterability of the volume having been previously acquired, both by
the liquid and by the pipe by means of the forced injection of a supple-
mentary volume of water, a space will be left vacant under the piston C
(Figure 4) when the hand presses on the handle D, but an equal space
will be occupied under the piston C¹ in consequence, and the space
which will be left under the piston C¹ when the hand ceases to press
upon the handle D and the counterpoise E presses in its turn upon the
piston an equal space will again be occupied under the piston C. The
mercury placed at the middle of the liquid thread participating actively
in the alternative to-and-fro motion is put in contact with the platinum
enclosed in the glass tube C¹, Figure 3, and breaking contact closes this
turn by turn, or interrupts at each turn the circuit of the electric
current between the interrupter, the receiver, and the pile. This current
alternately closed or interrupted naturally produces in the receiving
apparatus a line or a dot, according as the duration of the pressure
exercised by the hand has been more or less long.
If the receiving apparatus is one with a dial (whether a simple or
printing one), or if from any reason it is preferred that the pressure be
produced upon the piston by the power of an electro-magnetic current
instead of being exercised by the hand, the simple manipulator (Figure 4)
is replaced by the electro-magnetic manipulator, the thumbscrews of
which are put in relation with the pile, and the manipulator to be put in
movement by the aid of the hand. It follows from this arrangement
that at each movement of the said manipulator the current passing
successively either into the electro-magnet E or into the electro-magnet
F attracts alternately the two levers G and H, which fulfil relatively
to the said magnets the function of armatures. The movement in the
contrary direction simultaneously transmitted by these two levers to the
pistons depending from them. produces upon the liquid thread exactly

page_text: the same effect as the movement of the beam F of the simple manipulator
(Figure 4).
The putting together of the electro-magnetic manipulator with the
pipes and other apparatus, its fitting, &c.,, is the same as for the simple.
manipulator. In order to modify at will the stroke of the pistons of
the electro-magnetic manipulator two bolts I and K are used. Care
should be taken to never open this cock D (Figure 5) before having.
screwed the nut L, Figure 3, and to never unscrew it before having:
closed the said cock and determined the circuit of the current in the
clectro-magnet F. This precaution is indispensable to avoid the upward
pressure exercised by the water in the cylinder B, Figure 3, when the:
cock D, Figure 5, is open from lifting the piston D; Figure 3,, at the
moment when it should be down. In all cases also whether the simple
manipulator is used or the electro-magnetic manipulator it is always
necessary to close the cock D (Figure 5) before commencing, any trans-
mission, and it is necessary to open it as soon as the transmission is
terminated.
The effect produced by this manoeuvre, and by the arrangement
of the manipulator, of whatever kind it may be, with the regulating,
press is, that by any circumstance the volume of the liquid thread should
augment the piston of this press rises, and when it has arrived at the
maximum of its ascent an electric bell announces the fact automatically.
The cock E is then opened and the piston caused to descend one-half of
its whole course. If on the contrary the volume of the liquid thread
should diminish the piston B descends, and when it has reached the
maximum of its descent the electric bell announces this circumstance
also. One then injects by means of the pump H the quantity of distilled
water necessary to cause the piston B to rise the half of its total course.
In this manner one may be sure that in spite of the constant pressure to
which the liquid thread is submitted its volume will be always the same,
and in consequence there is no room to fear deterioration in the pipes
and apparatus, nor alteration in the regularity of the transmission. If it
should be perceived that the oxydation produced by the spark upon the
mercury has troubled the water the correspondent is directed to suspend
all transmission, the two cocks E, Figure 3, are closed, the washers F
are unscrewed, and the mercury is caused to rise in the glass tubes; the
troubled water is withdrawn, the mercury is cleansed with silk paper,

page_text: distilled water is poured through the orifices of the pipes K, the mercury
is caused to descend to its place, the washers F are screwed, the cocks F
opened, and notice is sent to the correspondent that he may recommence
the transmission of despatches.
It will be remarked that with the arrangements shewn in Figures 6
and 7 each correspondent can at will make use of the pipes of the cable
cither to send despatches simultaneously or to send and receive at the
same time, and that the sender is always able to control by means of the
interrupter, which is at the side of the manipulator, the arrival and
taking down of his despatch."
It is needless to enter into details concerning,-
1st. The arrangement of partial pipes intended to form the long pipes
which should compose the cable.
Secondly. The filling of these pipes with distilled water and deprived
of air.
Thirdly. The manufacture of the cable.
Fourthly. The manner of repairing ruptures in the cable, whether
those made purposely or by accident.
Fifth. The formula for determining at what distance from the shore
a rupture has taken place.
All these details ought to be executed by nearly ordinary means, and
not constituting Inventions properly so called, should have no place in a
simple description intended to accompany a demand for patent for the
principal object, that is to say, the theory and the application of the
hydro-electric cable.
From all that has been explained there results, -
First. That by the effect of constant pressure the liquid and the pipe
acquire the unalterability of volume and the capacity necessary to be
obtained by means of a given power the desired quickness of action.
(And it follows from our calculation that the necessary power to be
obtained with a cable of 2,500 miles, 4,000 kilometres long, a quickness
equal to 600 oscillations per minute, does not exceed 1 lb. 7 oz. troy,
with the stroke of 0.394 inches, if it is to be pressed by the hand;
6 lbs. troy with the stroke of 0.039 inches, if it concerns the attraction.
to be excrcised by the electro-magnetic. current.)

page_text: Secondly. That these pipes, completely filled with liquid, are protected
from all oxidation or incrustation so long as this liquid is distilled water
deprived of air.
Thirdly. That by the effect of the regulating press all augmentation
or diminution of volume in the liquid thread becomes absolutely
impossible.
We may then conclude that by employing an hydro-electric cable
2500 miles (4000 kilometres) long, and by disposing of the power as
above described, we should obtain,—
First. A quickness of transmission equal to 600' oscillations per
minute, which is equivalent to 860 despatches of twenty words per day,
and by a couple of pipes enclosed in the cable..
Second. A simultaneousness of transmission, that is to say, the faculty
of sending or receiving at the same time and with a single cable a given
number of despatches, this number being in relation with the number
of pipes enclosed in the said cable.
Third. The advantage of adapting to this cable all the systems of
telegraphy existing at present.
(1.) The direction of the current in the receiving apparatus can be
changed if necessary. In order to do this the platinum wire of the
tube C, Figure 8, should be suitably shortened, some slight modifications
must be made in the construction and action of the manipulator, and
the mercury must be put in contact with a third thumbscrew, making
use of the tubes B and H as conductors.
The price of a hydro-electric cable with four pipes, and suitable
therefore for the transmission of 1720 despatches for twenty words per
day, is about £68 per mile, laying down not included.
The duration of the hydro-electric cable is logically very long, if not
everlasting. On the other hand, an ordinary cable of the length of
2500 miles (4000 kilometres) can only give in answer about 180 des- 3
patches of 20 words per day (1540 less than the hydro-electric cable
with 4 pipes). Its price is about £74 per mile, laying not included,
£6 per mile more than the hydro-electric telegraph, and its existence
is continually in danger. A still greater saving can be effected in the
cost of the hydro-electric cables. For distances of not more than 28 or
30 miles simple apparatus like those represented in Figures 8, 9, 10,

page_text: and 11 may be used. These possess the advantage of being able to send
or receive simultaneously as many despatches as there are pipes in the
cable. Each of these pipes abuts separately on the one side in a
little tube of glass (A, Figure 8), and on the other in a little cylinder
provided with a piston (A, Figures 9 and 10).
These threads of platinum, which I call respectively Nos. 1, 2, and 3,
each communicate by one of their extremities with the limits B, C,
and D. (Fig. 8), and at the other extremity extend into the glass
tube A with the following arrangement:-No. 1 plunges deeply into the
mercury, No. 2 is only level with the surface, No. 3 extends a little
above the surface. In order that these 3 threads may be isolated one
from another even in touching it is sufficient that the threads No. 1
and 2 may be covered by a thin coating of gutta percha; one puts the
limits B and C in contract with the receiving apparatus and the pile.
The part of the cylinder A, Figure 9, which is underneath the piston,
the copper pipe, and the glass tube up to the point E, Figure 8, are
entirely filled with distilled water and deprived of air, from whence in
consequence a liquid thread proceeds without interruption from the piston
of the cylinder A, Figure 9, until contact with the mercury. The
lever B, Figure 9, supported by means of the screw C and the head of
the piston D upon a spiral spring, may be lowered either by the hand
or by the effect of the attraction of the electro-magnet E, opposite to
which it plays the part of an armature, and returns to its former
position as soon as the pressure of the hand or the attraction of the
electro-magnet ceases. The double nut F permits the stroke of the said
lever to be modified at will. The pipe of the cock G (Figure 10) is
united to the inner piece A Figure 11). When it is desired that the lever
should act by the effect of the attraction of the electro-magnet the
thumbscrews of the apparatus are put into contact with the piles, and
the manipulator is put in movement by the aid of the hand. It is
evident that as often as the lever causes the piston to enter in the
cylinder A the movement is transmitted to the mercury contained in
the glass tube, and the mercury in consequence is obliged to rise in
the left branch of this tube. It is evident that when the piston rises
into its place the mercury impelled by the weight of the atmosphere
descends again to its place. The mercury in rising and falling closes
and interrupts alternately the circuit of the electric current, as in the

page_text: ordinary interrupting apparatus of the long cable, and produces upon the
receiving apparatus precisely the same effects.
In order that the transmission may operate regularly in these con-
ditions it is necessary,-
First. That the apparatus represented by the Figures 8, 9, 10, and 11
should be all placed at the same level.
Second. That the copper pipes be sufficiently strong in order to be
able to support, without losing their shape, the pressure which must be
exercised upon the liquid thread in order to obtain the displacement of
the mercury with a given quickness, and that this pressure does not 1
exceed one atmosphere.
Third. That at each lowering of the piston a volume of additional water,
capable of producing in the-liquid thread the necessary compression to
overcome the resistance offered to it should be injected into the pipe.
Fourth. That the quantity of water contained in the pipe should remain 1
always the same, undergoing neither augmentation nor diminution of
´volume.
The conditions are easy to fulfil, since,—
First. It is easy to establish the three apparatus at the same height,
the water then serving as a level.
Second. For the distance of 30 miles a power of a little less than one
atmosphere is necessary in order to overcome the resistance due to the
friction of the liquid thread against the sides of the pipe. The weight
of the air will then suffice to produce upon the mercury the same effect
as the pressure of the lever has produced upon the piston, and this pressure 2
can be the cause of no inconvenience in the pipes as their proportions
render them capable of resisting without losing their form a pressure of
300 atmospheres.
Thirdly. In a cable of 30 miles in length each pipe contains about
35 gallons of water. In order to compress this water it is necessary to a
inject an additional volume of about 0.03 gallons which is easily obtained
by augmenting the section of the cylinder (A, Figure 8).
Fourth. The apparatus represented by the Figure 11 suffices to
keep the volume of the liquid thread always the same. By leaving open
the cock G (Figure 10) the tube B (Figure 11) will communicate with a
the liquid thread. But if the volume of the said thread diminishes the

page_text: .
.
water which flows constantly from the cock G replaces it, if it remains
stationary the water which constantly flows from the cock G, descends
into the receiver D which remains always empty in consequence of its
outflow pipe. On the other hand one is automatically warned if by
the effect of any cause independent of the will of the correspondent the
mercury overpasses the limits within which its level should be main-
tained. It can overpass these limits in the following cases :-By rising
above its ordinary level on the left branch or in descending beneath it. In
the first place the tinkling of the bell of the receiving apparatus indefinitely
prolonged will suffice to make the operator understand that it is not put
in motion by the correspondent. The mercury can be quickly brought
back to its proper level by allowing some drops of water to drop through
cock F, Figure 7: In the second case the mercury in descending
makes the contact cease between the platinum threads Nos. 1 and 2.
But these two threads by means of the limits B and C are in permanent
communication with one pile and in the electro-magnet the armature of
which when the circuit is closed stops a clock movement which being
set at liberty sounds a bell in the same condition as ordinary alarums.
It follows from this arrangement that during all the time that the
mercury preserves its ordinary level or mounts in the left branch of the
glass tube the circuit being closed the escape movement of the bell is
stopped, but from the moment when the mercury from some cause begins
to descend the circuit is interrupted, and the armature separating itself
from the electro-magnet by the effect of a spring disengages the
escapement of the bell which gives warning immediately that the
mercury is no longer at its ordinary level. One will then hasten to
cause it to rise by allowing to penetrate through the cock C, some
drops of water in the pipe H, by the aid of a pump which is always in
relation with the said cock.
It will be remarked that by employing the cable and the apparatus
which I have just described I can make use of almost all existing
systems of electric telegraph and that for this will as on account of
the quickness and simultaneousness of the transmission and on account
of the duration of the cable the two systems present exactly the same
advantages.
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, the

page_text: electric telegraph cable, and the apparatus connected therewith, sub-
stantially as herein-before described and illustrated in the accompanying
Drawings.
In witness whereof, I, the said Ferdinand Tommasi, have here-
unto set my hand and seal, this Sixth day of February One
thousand eight hundred and seventy-one.
FERDINANDO TOMMASI. (L.S.