A NEW OR IMPROVED MODE OF CONSTRUCTING ELECTRIC TELEGRAFHS AND VOLTAIC BATTERIES
Year: 1869

page_text: LETTERS PATENT to L'esmond Gerald FitzGerald, of Battersea, in
the County of Surrey, Electrician, for the Invention of "A NEW
OR IMPROVED MODE OF CONSTRUCTING ELECTRIC TELEGRAFHS AND VOLTAIC
BATTERIES."
Sealed the 13th August 1869, and dated the 18th February 1869
PROVISIONAL SPECIFICATION left by the said Desmond Gerald Fitz-
Gerald at the Office of the Commissioners of Patents, with his
Petition, on the 18th February 1869.
I, DESMOND GERALD FITZGERALD, of Battersea, in the County of
Surrey, Electrician, do hereby declare the nature of the said Invention
for "A NEW OR IMPROVED MODE OF CONSTRUCTING ELECTRIC TELEGRAPHS AND
VOLTAIC BATTERIES," to be as follows:-
My new or improved mode of constructing electric telegraphs prin-
cipally consists in the insulation of a signalling current, not as hitherto
by means of a dielectric or insulating material properly so termed, but
by means of good conductors of electricity (metals and electrolytes) so
arranged as to generate an electro-motive force which opposes the escape

page_text: of the signalling current when the latter is transmitted in a particular
direction; or, in other words, I prevent the passage or escape to earth of
the signalling current by generating an electro-motive force, which is
made to oppose such passage or escape of the signalling current, thus
allowing it to complete the line circuit. This mode of insulating the
signalling current. I term "electrolytic insulation," to distinguish it
from the ordinary mode of "dieelectric insulation." I also construct a
compound voltaic arrangement or battery upon the principle which is
adopted in the construction of telegraph cables or underground lines and
of "electrolytic insulators" according to the present Invention, namely,
by surrounding a voltaic element, which may be of any desired form,
with one or more hollow cylinders or vessels of which the interior surface
or surfaces constitute voltaic elements dissimilar to the above-mentioned
central element, and of which the exterior surface or surfaces consti-
tute voltaic elements of similar nature to the central element, these
compound hollow cylinders (or vessels of any desired form) being by
preference enclosed within another vessel of which the interior surface
only constitutes a voltaic element of opposite nature to the central
element. These vessels are merely separated by intervening layers of
electrolytic fluid or non-metallic material, nevertheless the battery pos-
sesses the same electro-motive force or tension as a battery of the same
number of couples constructed in the ordinary manner or insulated from
each other by means of non-conducting bodies or dielectrics. I also
construct a secondary battery in similar manner with the exception of
the surfaces of dissimilar metals.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Desmond Gerald FitzGerald in the Great Seal
Patent Office on the 18th August 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, DESMOND
GERALD FITZGERALD, of Battersea, in the County of Surrey, Electrician,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by. Her.
Letters Patent, bearing date the Eighteenth day of February, in the.
year of our Lord One thousand eight hundred and sixty-nine, in the
thirty-second year of Her reign, did, for Herself, Her heirs and suc-

page_text: cessors, give and grant unto me, the said Desmond Gerald FitzGerald,
Her special licence that I, the said Desmond Gerald FitzGerald, my
executors, administrators, and assigns, or such others as I, the said
Desmond Gerald FitzGerald, 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 "A NEW OR IMPROVED MODE OF CONSTRUCTING
ELECTRIC TELEGRAPHS AND VOLTAIC BATTERIES," upon the condition (amongst
others) that I, the said Desmond Gerald FitzGerald, 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 Desmond Gerald FitzGerald, 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 ;-
My new or improved mode of constructing electric telegraphs prin-
cipally consists in the insulation of a signalling current, not as hitherto
by means of a dielectric or insulating material properly so termed, but
by means of good conductors of electricity (metals and electrolytes) so
arranged as to generate an electro-motive force which opposes the escape
of the signalling current when the latter is transmitted in a particular
direction; or, in other words, I prevent the passage or escape to earth
of the signalling current by generating an electro-motive force, which
is made to oppose such passage or escape of the signalling current, thus
allowing it to complete the line circuit. This mode of insulating the
signalling current I term "electrolytic insulation," to distinguish it
I also
from the ordinary mode of or from "dielectric" insulation.
construct a compound voltaic arrangement or battery upon the
principle which is adopted in the construction of telegraph cables
or underground lines and of "electrolytic insulators" according to the
present Invention, namely, by surrounding. a voltaic element, which
may be of any desired form, with several hollow cylinders or vessels of

page_text: which the interior surfaces constitute voltaic elements dissimilar to the
above-mentioned central element, and of which the exterior surfaces
constitute voltaic clements of similar nature to the central element,
these compound hollow cylinders (or vessels of any desired form) being
by preference enclosed within another vessel of which the interior surface
only constitutes a voltaic element of opposite nature to the central
element. These vessels are separated by intervening layers of electro-
lytic fluid or non-metallic material, nevertheless the battery possesses
the same electro-motive force or tension as a battery of the same number
of couples constructed in the ordinary manner or insulated from each
other by means of non-conducting bodies or dielectrics. I also con-
struct a secondary battery in similar manner with the exception that I
do not adopt two dissimilar metals but one metal only in the construction
of the hollow cylinders or vessels of which the opposing surfaces con-
stitute the elements of the battery.
Having thus described the nature of my said Invention, I now
proceed to particularly describe and ascertain, with reference to the
accompanying Drawings, the manner in which the same is to be per-
formed or put in practice.
As the Invention relates to the construction of overland or aerial, of
underground, and of submarine lines of telegraph, as well as of voltaic
batteries and secondary batteries for various uses, the mode of carrying
it into effect will be explained under these several headings, commenc-
ing with the voltaic and secondary batteries, since it will be necessary to
refer to the latter in describing the remaining applications of the
Invention.
Voltaic Batteries.-In constructing according to my Invention a
battery of several alternations or couples or a compound voltaic arrange-
ment, I employ several concentrically arranged cups, cylinders, or
vessels, which with the exception of the outer one are constructed of
two different metals, the inner surface, for instance, being of lead or
copper and the outer surface of zinc. Within the central vessel I place
a plate or cylinder of zinc or other metal similar in its volta-electrical
nature to that constituting the outer surface of the concentric vessels,
and I also employ an outer vessel of a metal analagous to that con-
stituting the inner surface of the before-mentioned concentric vessels.
All these metallic pieces are separated from each other by an electrolyte,
such as water, or an aqueous solution, or by substances containing an

page_text: electrolyte, such as vegetable fibre saturated with a metallic or other
solution. Porous vessels may also be used between the metallic pieces
in conjunction with an electrolytic or with two different electrolytes
respectively in contact with the dissimilar metallic surfaces.
If
Referring to Fig. 1, a and b are two vessels of which the inner surface
is of lead or copper and the outer surface of zinc; c is a central element
of zinc; and d is an outer vessel of lead or copper. The shaded portions
of the Drawings between the metallic pieces may represent hemp
saturated with a solution of sulphate of zinc acidulated with sul-
phuric acid, or saturated with any other suitable "exciting fluid" or
electrolyte. The wire attached to d here constitutes the positive pole,
and that attached to the negative pole of a voltaic arrangement of
three cells in series, the electro-motive force and the electrical tension
being precisely the same as in the case of three cells of the ordinary
construction with elements and an electrolyte of the same nature.
porous vessels or diaphragms be inserted within the spaces separating
the opposing metallic surfaces, then, if a solution of sulphate of zinc or
acidulated water be placed within the porous cells, and if the space
outside the latter be filled with a solution of sulphate of copper, the
arrangement becomes exactly analagous to three cells of Daniell, con-
nected in series or for tension. In similar manner supposing the inner
surfaces of d, a, and b to be of platinum instead of lead or copper, and
the spaces outside the porous vessel to be filled with nitric acid, whilst
the spaces between the porous vessels and the zinc surfaces are filled
with dilute sulphuric acid, the arrangement becomes exactly analogous
to three cells of Grove. Any number of elements of any desired nature
may be similarly combined, each compound vessel similar to a and b
adding one alternation to the series. A convenient arrangement, when
very low tensions are not required, is a battery composed of a number
of separate series of from three to six alternations, as above, which can
be connected either by their opposite poles (for tension) or by their
similar poles (for low internal resistance or "quantity").
I do not confine myself in the construction of this form of battery to
the metals zinc (for the positive element) and lead or copper (for the
negative clement), nor to the arrangement in which the positive ele-
ment is central; but I claim, the use of any metals capable of generating
a voltaic current (and also of charcoal as a negative element), arranged
in the above manner, or vice versa, with the central element negative

page_text: instead of positive.
The concentric vessels may be only partially con-
structed of metal; thus a number of hollow cylinders of metal and a
central clement may be cemented to a stand of wood or other material,
which closes the lower extremities of the cylinders and maintains these
and the central element in place. The battery of three, six, or more
alternations may thus be charged with "exciting fluid," or emptied with
the greatest possible facility.
Secondary Batteries.-In secondary batteries constructed according
to my Invention the arrangement of the elements is the same as in the
primary or voltaic batteries above described; but the opposing surfaces
are all of similar nature, the central element and the surrounding
concentrically disposed vessels being by preference formed throughout
of a given metal, such as lead, copper, or platinum. The metallic pieces
may, however, be formed of any metal electro-plated or otherwise
covered with another metal, so that the opposing surfaces may be of
similar nature. These opposing surfaces are separated from each other,
as in the case of the primary or voltaic batteries before described, by an
electrolyte, or by substances containing an electrolytc.
A secondary battery of four elements is represented in Fig. 2. a, b,
c, d, and e are five concentric hollow cylinders (or e may be made solid)
of any suitable metal, such as lead. These cylinders are cemented to a
.stand S of any suitable (non-metallic) material, and the spaces between
them contain an electrolyte, such as acidulated water, or a solution of
sulphate of zinc, or vegetable fibre saturated with any aqueous solution.
When the cylinders a and e are respectively connected with the poles
of a primary or voltaic battery the secondary arrangements (which at
the onset is perfectly inert or possessed of no electro-motive force, and
allows the current from the primary battery to pass freely) becomes an
electro-motor similar to the primary battery, though possessing an
electro-motive force always less than that of this primary or charging
battery and capable of producing a current only during a limited space
of time. The secondary arrangement then resists the passage of the
current from the primary or charging battery, this current becoming
less and less in intensity until it is (under ordinary conditions) almost
entirely arrested, as it would be by a second primary battery of some-
what less electro-motive force opposed to the former, or by a dielectric
or ordinary insulating material. Thus if the electro-motive force of the
primary or charging battery be diminished to a slight extent, as, for

page_text: instance, by removing one of the couples in series, the primary and
secondary batteries opposed to each other will become equal in electro-
motive force, and the current through the circuit formed by their
conjunction will be completely and permanently arrested. The poles
of the primary battery (as well as those of the secondary battery) may
then be said to be perfectly or absolutely insulated from each other, as
they would be by a dielectric or insulating material, properly speaking,
of infinite conductive resistance. It is this mode of insulation due to
the polorisation of an electrolyte or to the action of an opposing electro-
motive force (in either a secondary or a primary battery or electro-motor)
that I term "electrolytic insulation," and that I utilise in various ways
in the construction of telegraphs by surrounding a conducting wire with
several concentric layers of polarised electrolyte, each of which gives a
fresh accession of electro-motive force, opposing the escape of the
signalling current.
A number of separate series, such as that shown in Fig. 2, may be
connected with a primary battery in such a manner that one set of poles
of the secondary battery arranged in multiple series is in contact with
one pole of the primary battery, and the other set of poles of the
secondary battery in contact with the other pole of the primary battery,
or, in other words, in such a manner that the secondary battery shall
oppose the least resistance to the passage of the current from the
primary or charging battery. If then, by means of a commutator,
all the separate series, including the primary battery, be connected
together in simple series the most brilliant effects due to the passage of
a voltaic current through a circuit of great resistance may temporarily
be produced, such, for instance, as the electric light between charcoal
points. Or if the external portion of the circuit be of comparatively
small resistance a current of very great intensity may temporarily be
produced by simultaneously connecting the opposite poles of all the
separate series through the external portion of the circuit. The
secondary battery may of course be constructed with concentric vessels
wholly of metal instead of cylinders cemented to a wooden stand.
Overland Lines-In the construction of overland lines of telegraph
instead of using the ordinary "dielectric" insulators of porcelain, glass,
and such like substances I support the line wire at the necessary intervals
by means of an "electrolytic insulator," of which one description
consists of a small primary electro-motor or battery of suitable form and

page_text: In con-
possessing an electro-motive force sufficient for the object in view. I
attach or suspend the conducting wire to one of the poles of this electro-
lytic insulator in such manner that the electro-motive force of the latter
opposes the passage to earth of the current from the signalling battery
when this current is transmitted in one particular direction, that is to
say, if the negative pole of the signalling battery is to be brought into
contact with the line wire for the production of signals I attach or
suspend the line wire to the negative pole of the electrolytic insulator;
or, if the current to line is to be from the positive pole of the signalling
battery I attach the line wire to the positive pole of the electrolytic
insulator, of which the construction is varied accordingly..
structing this description of electrolytic insulator I employ, by preference,
a modification of the primary or voltaic battery described above as form-
ing a portion of the present Invention. One form of this description of
electrolytic insulator is shown in Fig. 3, which represents a three-cell
insulator of which the picce in the shape of a truncated cone with
its narrow extremity downwards and ending in a book, ring, or other
attachment for the line wire is of galvanized iron and is partially
surrounded by a "separator" of felt, hemp, paper pulp, or other
porous material, which when in a moist condition acts as an electrolytic
conductor, and which may be saturated with any solution susceptible
of undergoing electrolysis or of increasing the electro-motive force of
the arrangement. The piece thus covered with the separator is
enclosed within the hollow metallic cone c of which the interior surface
is of copper, lead, or other metal electro-negative to zinc, and the
exterior surface of zinc or other metal electro-positive to copper. The
picce c is in its turn coated with or partially surrounded by a separator
similar to the first, and is then enclosed within a second similar but
larger cone e formed with dissimilar metallic surfaces as above and
coated with a separator. Any number of pieces similar to cand e and
coated externally with a separator may be added; and lastly the hollow
conical piece n formed of one metal only and constituting a negative
element in and the positive pole of the voltaic arrangement is applied.
The arrangement may then be enclosed within a ring of wood the
interior surface of which is conical, and the ring of wood may be secured
to a ring of iron R by means of screws, as shown at s, this ring of iron
being constructed with any suitable appendages to allow of its being
attached to a telegraph post or other support. A plate p of metal or
other material protects the electrolytic insulator from excess of moisture.

page_text: I do not, however, in constructing this description of electrolytic
insulator (which is essentially a primary voltaic arrangement of con-
siderable electro-motive force, (though from its high internal resistance
it may be scarcely capable of producing an appreciable dynamical effect)
confine myself to this or to other modifications of the compound primary
voltaic batteries included in the present Invention; but I employ any
suitable form or arrangement of the elements which will allow of an
electro-motive force being generated so as to oppose and prevent the
escape of the signalling current.
Fig. 4 represents another form of the primary electrolytic insulator in
which the concentric arrangement of the elements is not adhered to.
In this a number of rings or links each of which is formed of two dis-
similar metals are united, preferably, by means of vegetable fibre, which
may be saturated, as mentioned heretofore, with any suitable solution so
as to constitute a voltaic chain, of which one pole forms a support for
the line wire whilst the other is in contact with earth. The metal links
may be of galvanized iron partially coated with copper or other metal
electro-negative to zinc by electro-deposition.
It may here be explained that the fibrous or porous materials of which
the "separator" is formed and which intervened between the elements in
the various forms of electrolytic insulator need not be in a perceptibly
moist condition, since the quantity of moisture which such materials
must necessarily absorb from the atmosphere is ordinarily amply
sufficient (however minute this quantity may be) to generate by its
contact with dissimilar or "polarised" metallic surfaces the clectro-
motive force which opposes and prevents the lateral escape of the
signalling current. In proportion as the quantity of moisture contained
in these fibrous or porous materials may be diminished, so the "resist-
ance" of the electrolytic insulators will be increased, whilst the electro-
motive force which acts independently of this resistance to conduction
in opposing the passage to earth of the signalling current will be scarcely
effected until almost the last traces of moisture are expelled or absorbed
from the fibrous or porous materials. Supposing this to happen from
the effect of great heat and drought the resistance of the insulators would
then be so great as to render them precisely analogous in their action
to the ordinary or "dielectric" insulators.
It should also be explained that the metallic elements in the several
forms of electrolytic insulator, as shown in Figs. 3 and 5, need not,

page_text: electrically speaking, be of any greater thickness than an ordinary sheet
of paper, and that their surface also may be as small as is practically
and mechanically desirable, since the object is to construct not an
electro-motor capable of generating a strong or even an appreciable
current, but one capable merely of generating an electro-motive force
which, measured as a statical tension, is equal to and of the same "sign
as the tension of the line wire at the point of support.
دو
I have found that it is not necessary to employ
a primary voltaic
arrangement for the electrolytic insulation of aerial or other telegraphic
lines, and that the insulation from earth of a signalling current may be
conveniently and efficaciously accomplished in the case of aerial lines,
by means of a second description of electrolytic insulator, which is a
modification of the secondary battery shown in Fig. 2. The secondary
battery which constitutes this description of electrolytic insulator
becomes charged or converted into an electro-motor by the action of the
(primary) signalling or line battery, and may easily be permanently main-
tained in the condition of a battery, of which the clectro-motive force
opposes the escape of the signalling current.
c, and
In Fig. 5, which represents one form of the insulator in question, a, b,
are thin hollow conical elements of lead, copper, or any other
suitable metal, which are prevented from coming into metallic contact
by means of "separators," as previously described. The element é also
partially surrounded by a separator is of similar nature, but is con-
structed of sufficient strength to carry the hook or ring which supports
the line wire. The piece is a ring or hollow cylinder of wood, having
its interior surface conically shaped, so as to act as a support to the
arrangement of secondary elements. R is a ring of iron to which the
wooden piece is fastened, and by means of which the electrolytic
insulator is attached in any convenient manner to the telegraph post; it
carries a plate or disc p which protects the arrangement from excess of
moisture from rain.
Another form of this description of electrolytic insulator is shown in
Fig. 6, the elements being here disposed horizontally, with the line wire
passing through the axis of the cylinders. The outer cylinder R is
preferably of galvanized iron, and is constructed with a clamp or screw.
to affix it to the telegraph post or other support. The extremities of the
wire W may be secured to the line wire on either side in the usual way
(by twisting or binding together and soldering), or the line wire may be

page_text: passed through the axis of the insulator, and subsequently joined to
another length of wire.
Referring to Fig. 7, I have now to describe the general arrangements
for alternate signalling between the stations S and S'. If the electrolytic
insulators E, E, be of the first-mentioned description (that is, primary
voltaic electro-motors) the signalling batteries B, B', must be so dis-
posed that their electro-motive force is opposed to that of the electro-
lytic insulators, that is to say, if the hooks or other supports for the line
wire attached to these insulators constitute positive poles, then the
positive poles of the signalling batteries must also be brought into contact
with the line wire, and vice versa. If the electrolytic insulators be of
the second description (that is, secondary batteries or electro-motors)
then either the positive or the negative poles of the signalling batteries B
and B' may be brought into connection with the line wire, but both the
poles thus connected must be of the same "sign." The signalling instru-
ments I and I may be placed in the circuit either as shown in the
Figure or at i, i. The manipulator at S transmits signals to S' by
depressing the key k, which short circuits the battery B and allows a
current from the battery B' to pass through the line circuit. In similar
manner the operator at S' transmits signals to S by depressing the key
A which short circuits the battery B' and allows a current to pass from B.
Underground Telegraphs.--The methods by which I effect the insu-
lation of underground lines of telegraph are essentially the same as those
which I adopt in the insulation of overland lines by means of electro-
lytic insulators; or, in other words, the insulation of underground lines
is accomplished by surrounding the conductor with successive layers of
an electrolytic conductor, such as vegetable fibre, containing more or
less moisture or moisture and saline compounds, which layers or con-
centric envelopes of electrolytic material are polarised by means of
hollow cylinders or tubes separating them and constituting with the
electrolyte and central conductor a primary or secondary electro-motor.
But in underground lines the electrolytic insulation requires to be con-
tinuous, whereas in the case of overland lines the insulation of the
conductor, excepting at the points of support, is effected by the dielectric
air.

page_text: construction either of a primary or a secondary electro-motor opposing
and preventing the lateral passage of the signalling current through the
layers of electrolytic material surrounding the conducting wire.
I give the following as an example of my first method of constructing
an underground telegraph cable, it being understood that I do not
confine myself to the use of the metals or the electrolyte employed in
this instance.
(I.) A galvanized iron wire of suitable diameter is covered with a
layer of fibrous material (cotton or hemp) saturated with a solution of
sulphate of zinc.
(II.) The wire so covered is then encased in a thin tube or covering of
lead, and this leaden tube or covering is subsequently coated with a thin
layer of metallic zinc, preferably by passing it through a bath of sulphate
of zinc under the conditions necessary for the electro-deposition of the
metal.
(III.) The zinc-coated tube is then covered with a layer of fibrous
material saturated as before with a solution of sulphate of zinc.
(IV.) A second and (according to the degree of electrolytic insulation
required) in some cases a third and fourth covering of thin sheet lead
may be applied, each metallic covering being slightly coated with zinc
by electro-deposition, and surrounded with a layer of fibrous material.
(V.) A thicker covering of lead, which is required to be quite im-
pervious to water, is lastly applied, as well for the purpose of externally
protecting the cable as to act as a negative element in its construction.
Notwithstanding I have above described the mode and means to be
adopted in constructing a cable constituting a primary and voltaic
electro-motor, I have found that in the electrolytic insulation of under-
ground or submarine lines it is not necessary that the cable should con-
stitute a primary voltaic arrangement, and that such insulation may
be conveniently and efficaciously performed by means of a series of
concentric tubes or coverings of one metal only, enclosing the conductor
continuously, and separated from each other by layers of electrolytic
material as before. By the action of the signalling (primary) batteries,
disposed as shown in Fig. 8, the opposing surfaces of the metallic
elements of the cable as well as the electrolytes enclosed between
them become polarised, or electro-chemically affected, in such manner

page_text: that the cable when thus charged as a secondary electro-motor opposes
a sufficient electro-motive force to the lateral passage or escape of the
currents transmitted from the signalling batteries. The cable in fact
constitutes a secondary battery, which when charged or polarised by
means of four, six, eight, or ten cells of a primary electro-motor may,
according to the number of concentric clements employed in its con-
struction, effect the absolute insulation of a current traversing the
central conductor from a signalling battery of a less number of elements
than the charging battery, or of two, four, six, or eight cells. The
principle that no current can pass through the circuit formed by
opposing to each other two batteries of equal electro-motive force is here
exemplified. The signalling batteries may advantageously, however,
be of considerably greater electro-motive force than that which it is
possible to communicate to the electrolytically insulated cable, and may
thus constitute also the charging or polarising batteries. Supposing,
for instance, that the maximum electro-motive force under given con-
ditions of the secondary electro-motor constituting the cable be equal
to that of six cells of Daniell, then, if the signalling batteries be formed
of eight cells of Daniell in single series, the signalling current will be
of the same intensity as that of a current from six cells of Daniell
traversing a conductor equal in resistance to the line wire, and insulated
from earth by an infinite resistance, whilst a current under an electro-
motive force of two cells of the signalling battery will pass laterally
from the wire, with the effect of maintaining constant its electrolytic
insulation.
I give the following as an example of my second system of con-
structing an underground telegraph cable, it being understood that I
do not confine myself to the use of the metal lead in the construction
of the concentric tubes, or to the fibrous material and electrolyte employed
in this instance.
(I.) A galvanised or ordinary iron wire of suitable diameter is covered
with a slight coating of fibrous material (cotton or hemp) saturated with
a solution of a salt of zinc.
(II.) The wire so covered is then encased in a thin tube or covering
of lead, which in its turn is coated with fibrous material as above.
(III.) A second and in some cases (according to the degree of
electrolytic insulation required) a third and fourth covering of thin

page_text: fibrous material, as above.
(IV.) A thicker and impervious tube or covering of lead is lastly
applied as an external protection to the cable, as well as to act as an
element in the secondary arrangement.
In joining several lengths of cable constructed according to either of
the above methods it is necessary only to bring into metallic contact
respectively the inner conductors in the several portions of cable and
the outer tubes or coverings of the same. The inner conductors may
be united either directly by means of a scarf joint and soldering, or
indirectly by means of a copper or other wire helically arranged around
these conductors, and soldered to them respectively at each extremity.
And the outer tubes or coverings may be united by means of a short
length of metallic tubing of sufficient diameter to enclose these outer
tubes or coverings, and united to them at each extremity by means of
solder, screw joints, or otherwise. The arrangements for alternate trans-
mission and reception between two stations are the same as in the case
of overland lines of telegraph, and will be sufficiently understood by
inspection of Fig. 8.
Submarine Telegraphs.-The construction of electrolytically insulated
cables for submarine. telegraphs differs from that of cables for under-
ground lines merely in the addition of materials, such as iron or
steel wires, for obtaining a greater degree of strength in proportion to
weight. The cable may be externally surrounded wholly or in part
with such wires, longitudinally or helically disposed. In many cases a
thicker and longitudinal covering of hemp applied to each of the
cylindrical elements of the cable will suffice to obtain the necessary
degree of strength.
Having now particularly ascertained. and described the nature of the
said Invention, and in what manner the same is to be performed, I
hereby declare that I do not claim as my Invention the arrangement in
which a voltaic element is enclosed within a single cylinder or vessel in
order to constitute a single voltaic (primary) or secondary couple, such
an arrangement being exemplified in the ordinary form of Daniell's
battery.

page_text: And, further, I do not claim as my Invention the use of a single tube
or covering of metal surrounding a telegraphic conductor enclosed within
any material whatsoever, although I include in my claim, as set forth
below, the arrangement of signalling apparatus for the purpose of
signalling through an electrolytically insulated conductor, which is
illustrated in Fig. VIII., and by which a conducting wire, if enclosed
within a suitable electrolytic conductor, and surrounded by a single
tube or covering of metal, may be rendered to some extent efficient for
the transmission of signals (though far less so than when a series of tubes
or coverings and electrolytes is employed as above indicated), provided
the other conditions which I have pointed out as necessary be duly
complied with.
Also I disclaim the use of any of the metallic elements in my
electrolytically insulated telegraphic lines or cables, as a couple or as a
battery for the generation of electric currents, to produce the signal upon
the instrument at the receiving station; or, in other words, I employ
always separate batteries, as indicated in the above Specification and in
the accompanying Drawings, for the production of the signals, since,
even where it might be possible to use a cable as an electro-motor in
producing dynamical effect, such use would necessarily lead to its speedy
deterioration and destruction.
But what I claim as my Invention is substantially the arrangement
in which a metallic element or conductor of any form or dimensions is
surrounded by several (two or more) concentric layers of material com-
posed of or containing an electrolytic conductor, such layers of
electrolytic material being separated from each other and from earth by
means of metallic vessels, hollow cylinders, tubes, or coverings in order
that such arrangement may constitute a compound primary or secondary
battery or electro-motor.
And I claim also as my Invention the electrolytic insulation of a
signalling current as above described, and the arrangements for the
alternate transmission and reception of signals through an electro-
lytically insulated conductor (which are illustrated in Figs. 7 and 8),
whether this conductor be surrounded at intervals or continuously by a
single cylindrical layer of polarised electrolytic material or by several
such layers, as in the methods of constructing efficiently insulated over-

page_text: land, underground, or submarine lines of telegraph indicated and
described in the above Specification.
In witness whereof, I, the said Desmond Gerald FitzGerald, have
hereunto set my hand and seal, this Sixteenth day of August, in
the year of our Lord One thousand eight hundred and sixty-nine.
DESMOND G. FITZGERALD. (L.S.)
Witness,
ALEX". P. WRIGHT,
Secy., Inventors' Patent Right Association, Limited,
21, Cockspur Street,
Charing Cross,
London, S.W.
Patentee's Agentel