IMPROVEMENTS IN AND RELATING TO TELEGRAPHIC AND TELEPHONIC APPARATUS
Year: 1883

page_text: LETTERS PATENT to Henry Harris Lake, of the firm of Haseltine, Lake,
and Co, Patent Agents, Southampton Buildings London, for an Invention
of "IMPROVEMENTS IN AND RELATING TO TELEGRAPHIC AND TELEPHONIC
APPARATUS" communicated to him from abroad by François Van Rysselberghe
of Schaerbeck, in the Kingdom of Belgium
PROVISIONAL SPECIFICATION left by the said Henry Harris Lake at
the Office of the Commissioners of Patents on the 23rd November 1883.
HENRY HARRIS LAKE of the firm of Haseltine, Lake, and Co Patent Agents,
Southampton Buildings, London "IMPROVEMENTS IN AND RELATING TO TELE-
GRAPHIC AND TELEPHONIC APPARATUS"-[A communication to him from abroad
by François Van Rysselberghe of Schaerbeck, in the Kingdom of Belgium]
This invention relates to telegraphic and telephonic apparatus.
The said invention comprises the combination and arrangement as hereinafter
described of telephonic and telegraphic apparatus whereby ordinary telegrams sent
by the Morse, Hughes, Wheatstone or other apparatus, and telephonic conversations
may be simultaneously transmitted by the same wire or wires over long distances
It is essential that the telegraphic branches should not be connected with the
earth, except by high resistances. It is also essential that the telegraphic currents
should rise to their maximum strength and diminish gradually, and that ordinary
sudden currents, such as those resulting from the closing and opening of circuits
without precaution, should not be employed
And in order to obtain these gradual currents I employ electro-magnets of a
resistance of about 500 ohms, intercalated in the line at the points of departure
and return or interposed between the battery and the manipulator; or I employ
condensers placed in derived or branch circuits from the line at the departure and
at the return; or I employ a combination of electro-magnets and condensers, the
arrangement which I prefer being that shewn in Figure 1, in which M is the
manipulator, P the battery, R. the telegraphic receiver, the electro magnet of which
must not have a resistance much less than 500 ohms. A1 and A2 are electro-

page_text: magnets of about 500 ohms resistance, C is a condenser of about 2 microfarads and t
is the earth.
The dimensions of the electro-magnet, which I have found very suitable, are as
follows, viz-diameter of the iron core 15 millimetres; length 70 millimetres; and
when several electro-magnets are placed upon the same board, in order to prevent
their exerting any injurious reciprocal influence upon each other, I enclose each
electro magnet in a cylinder of soft iron and I arrange each cylinder in such a
manner that its axis is perpendicular to the middle of the axis of the adjacent
cylinder
I also obtain gradual currents by the employment of a manipulator provided
with a rheostat operating in such a manner that at the closing of the circuit it
interposes a gradually decreasing resistance and at the opening of the said circuit it
interposes a gradually increasing resistance.
I have ascertained, and this forms an important feature of the present invention,
that the gradual currents obtained by either of the above described means are
inaudible and not perceptible in the telephone either directly or by induction, that
is to say, neither the primary currents, nor the derived or induced currents which
proceed therefrom are heard in the telephonic receiver, and by reason of this fact
telephonic conversations can be carried on not only by means of wires attached to
the said posts, carrying the telegraph wires, when the latter are only traversed by
gradual currents, but by means of the said telegraph wires.
In fact, assuming that, in order to avoid telephonic induction, the wires of one
line are coupled two and two, each couple forming relatively to the other wires of
the same line a symmetrical system as perfect as possible. Then, in order to utilize
for the transmission of spoken messages, a couple consisting of two telegraph wires;
or in order to utilize for telegraphy a couple consisting of two ordinary telephonic
wires transmitting spoken messages, I have recourse to one or the other of the
following arrangements, viz:-
First arrangement in which each system of double wire furnishes a communication
for speech and a single telegraphic communication
Let L' and L2 (Figure 2) be the two wires of a couple; A¹ A² A³ three electro-
magnets of about 500 ohms resistance, the two first occupying the two sides of a
Wheatstone bridge, and the third being interposed between the battery P and the
manipulator M; R the receiver of a telegraphic installation MRP; C, C two
condensers of about half a microfarad intercalated with an ordinary telephonic
installation T upon the diagonal p, q of the Wheatstone bridge; and S a suitable
resistance placed either upon oue of the two lines or upon one of the sides of the
bridge, or upon each of the two lines; it will always be possible, by properly
regulating the resistance S, to cause the points p and q to be maintained at the
same potential for all currents emitted at M, or for all currents of equal intensity
caused to pass in the same direction upon the two lines L' and L. The telephone
will then not be influenced either by the telegraphic currents or by the induced
currents acting simultaneously upon the two lines L' and L². But the telephonic
conversation will be carried on by the double wire as if the telephonic installation
alone existed.
It is not indispensable that A1, A2 and A³ should be electro-magnets, they may
be simple resistances each of about 500 ohms.
L' may be an artificial line reduced to a simple resistance S, connected on the
one hand with the point q and on the other hand with the earth t. A telephonic
communication and a telegraphic communication are thus obtained by means of a
single wire L'
Second arrangement in which each system of double wire furnishes a com-
munication for speech and two telegraphic communications
Let L L (Figure 3) be the two wires of a couple; P M¹ R¹ and P2 M² R² two
telegraphic installations of any description, in which the receivers R¹ R have
always a resistance not much less than 500 ohms; A¹, A2 A3 A' electro-magnets of
about 500 ohms resistance; C¹ C* condensers of about two microfarads; C³, C* two

page_text: condensers of equal capacity each of about half a microfarad; B1, B2 B3 an induc-
tion coil with three circuits, that is to say, two equivalent secondary circuits B¹, B¹
which terminate respectively at the earth t and at the condensers C³, C; and a
single primary circuit connected on the one hand to the earth t and on the other hand
to a telephonic wire L³ upon which is placed an ordinary telephonic station T. The
induction coil B', B3, B³ will then form a differential system.
Third arrangement in which each double conductor furnishes two telegraphic
communications and one communication for speech
This arrangement is illustrated in Figure 4 in which similar letters of reference
indicate instruments similar to those in the preceding Figures. The only condition
to be fulfilled, in this case, as regards the value of the resistances is that:-
S¹ × L³ S³ × L'
and it will sufficient to fulfil this condition approximately if S₁ and S² are electro-
magnets instead of simple resistances.
It will be moreover possible to place the differential coil with the telephonic
station upon the connection p³, q' in the manner above indicated for the connection
p. q in Figure 3.
Fourth arrangement.
In the above described arrangements, it is assumed that the two telegraph wires
constituting the double conductor, terminate on the one hand and on the other
hand in the two localities where the telephone is to be used; but this is not
indispensable;
In fact, let L' L' (Figure 5) be two telegraph wires attached to any kind of
telegraphic installations what ever may be their origin and destination, but parallel
between the localities O and V. The latter will be in telephonic communication by
means of the arrangement shewn in Figure 5, in which A' A' A³ A* are electro-
magnets of at least 500 ohms resistance; 01 02 05 06 condensers of half a
microfarad; C3 C C7 C condensers of two microfarads; and T¹ T2 two ordinary
telephonic stations, or by preference the installation shewn upon the connection p q
in Figure 3.
:
The differential coil B¹ B B³ in Figure 3 may be advantageously constructed in
the following manner, illustrated in Figure 6, in which N is a soft iron core upon
which is wound the primary circuit B³. Upon this primary coil and capable of
sliding thereon are the two equivalent secondary coils B' B². It will be possible,
even if the latter are not identical, to cause them to exert upon B³ an equivalent
action by placing them in a suitable position relatively to B³. t1, t2, T, L' and L'
are terminals connected as follows that is to say, T with the telephonic station;
t' and t with the earth; L' and L³ with the two telegraphic lines by the medium of
condensers.
This differential system may be also constructed in another manner as shown in
Figure 7.
Two ordinary induction coils identical with each other, are placed perpendicularly
to one another and coupled in the following manner, that is to say-the primary
circuits B B connected for quantity and the secondary circuits. D¹ D' connected
for tension and the terminals connected respectively, T with the telephonic station;
t' and t with the earth; L1 and L2 with the two telegraphic wires by the medium
of condensers. The soft iron cores N¹ N² are movable, that is to say, they can be
inserted more or less into the coils. And even if the two coils are not identical,
they may be caused to exert an equivalent action and thus constitute a perfect
differential system.
When telephonic induction is not to be taken into consideration, telegrams and
spoken messages may be transmitted by a single wire by adopting the arrangement
above described at the end of the description of the first arrangement (L³ may be
an artificial line &) or by employing the following arrangement.
Fifth Arrangement (Figure 8) M is the manipulator, P the battery and R the
receiver of the telegraphic station, the electro-magnet of which receiver must not

page_text: have a resistance much less than 500 ohms; A' and A2 are two electro magnets of
about 500 ohms resistance; C¹ is a condenser of two microfarads; C² is a condenser
of half a microfarad; and T is an ordinary telephonic station for receiving and
transmitting speech.
When it is only required to transmit spoken words to short distances, the
existing microphonic installations of Blake, Ader or others, actuated by one or more
Leclanchè or Daniell elements will answer the purpose. But where it is required
to transmit speech to great distances, it is important to introduce at the microphonic
station the following improvement the principle of which I will now proceed to
describe.
When the microphone is used with an induction coil the induced currents proceed
from the variations in the intensity of the inducing current and these variations
are caused by the variations in the resistance which the imperfect contacts of the
microphone oppose to the current. All things being equal, these variations in the
resistance of the contacts have the greater relative value, and the variations in
the current which result therefrom are the more considerable when the total
resistance of the circuit is less. In fact, let. E be the electromotive force of the
battery of the microphone; R³ the resistance of the said battery; R³ the mean
resistance of the microphonic contacts; S the constant sum of all the other
resistances; and I the intensity of the microphonic current; then
I
=
E
++3
and d I =
=
R¹ + R² + S
E
2 d R³
(R1 R² + S)
= 0.
It will be seen that d I has its maximum value when R¹
It is therefore necessary to employ, in order to produce the inducing current, an
electromotive source with an extremely feeble internal resistance. Secondary
batteries or accumulators and thermo-electric piles are such sources and as these
apparatuses have not been used heretofore for the special purpose above indicated
their application to the microphone forms a feature of the present invention.
Figure 9 shews clearly how I effect this application. H is a secondary battery
or accumulator or a thermo-electric pile, K is the microphone, B is an induction
coil, L the line and t the earth.
But in order that this application may render all the advantage that can be
derived from it, a microphone of very feeble resistance must be employed, for
example, a microphone with multiple contacts all arranged in quantity as indicated
in Figure 10 which shows a microphone with 8 parallel series, the total resistance
of which does not exceed 2 ohms, whilst the microphone with two contacts shewn
in Figure 9 has a resistance of about 16 ohms, it is also necessary that the primary
circuit of the coil B should have very little resistance. I have found that, with the
microphone shewn in Figure 10 the resistance of the primary circuit should not
exceed 0-2 ohm.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Henry Harris Lake in the Patent Office on the 20th May
1884.
HENRY HARRIS LAKE, of the firm of Haseltine, Lake, and C° Patent Agents,
Southampton Buildings, London, "IMPROVEMENTS IN AND RELATING TO TELE-
GRAPHIC AND TELEPHONIC APPARATUS." A communication to me from abroad by
François van Rysselberghe, of Schaerbeck, in the Kingdom of Belgium,
This Invention relates to telegraphic and telephonic apparatus.
The said invention comprises methods, and combinations and arrangements of
telephonic and telegraphic apparatus, as hereinafter described, whereby ordinary
telegrams sent by the Morse, Hughes, Wheatstone or other apparatus and telephonic
conversations may be simultaneously transmitted by the same wire or wires over
long distances.
It is essential that the telegraphic branches should not be connected with the
earth, except by somewhat high resistances. It is also essential that the telegraphic
currents should rise gradually to their maximum strength and diminish gradually,
and that ordinary sudden currents, such as those resulting from the closing and
opening of circuits without precaution, should not be employed.
And in order to obtain these gradual currents, I employ, at the transmitting
station, electro magnets of a resistance of about 500 ohms, intercalated at the
departure end between the manipulator and the line, or between the battery and
the manipulator, or I employ condensers, placed at the departure end in derived or
branch circuits from the line; or a combination of electro-magnets and condensers;
the arrangement which I prefer being the combination of two electro-magnets
placed one behind the other with a condenser in a derived or branch circuit between
them. An arrangement of this kind is shewn in Figure 1, in which M is the
manipulator, P the battery, R. the telegraphic receiver, the electro-magnet of which
must not have a resistance much less than 500 ohms. A₁ and A, are electro-
magnets of about 500 ohms resistance; C is a condenser of about 2 microfarads
and t is the earth.
This combination of two successive electro-magnets with a condenser between
them may be advantageously placed between the battery and the manipulator, but
one of the faces of the condenser being always connected to the line, the other is
connected to the point of junction of the two electro-magnets (Figure 2)..
The dimensions of the electro-magnets, which I have found very suitable, are as
follows, viz;-Diameter of the iron core 15 millimetres; length 70 millimetres;
and when several electro-magnets are placed upon the same board, in order to
prevent their exerting any injurious reciprocal influence upon each other, I enclose
each electro-magnet in a cylinder of soft iron and I place each cylinder in such a
manner that its axis is perpendicular to the middle of the axis of the adjacent
cylinder.
I can also, in special cases, employ a combination which consists in placing a
number of successive condensers in derived or branch circuits between the line and
the earth, with electro-magnets of increasing resistance between the line and each
condenser. An arrangement of this kind is shewn in Figure 3, in which C₁, C₂, C³
are condensers of about 2 microfarads; R₁ a resistance practically nil, R, an
electro-magnet of 1000 Ohms, and R, an electro-magnet of 3000 Ohms. R, and R.
might-be-simple resistances, but the result would not be as good.
I also obtain gradual currents by the employment of a manipulator provided
with a rheostat, operating in such a manner that at the closing of the circuit it
interposes a gradually decreasing resistance, and at the opening of the said circuit
it interposes a gradually increasing resistance.
I call a current-graduator any apparatus or combination such as those above
described which will cause the currents to gradually increase to their maximum
strength and to gradually decrease until they become extinct.

page_text: I have ascertained, and this forms an important feature of the present invention,
that the gradual currents obtained by one of the above described means are inaudible
and not perceptible in the telephone either directly or by induction, that is to say,
neither the primary currents nor the derived or induced currents which proceed
therefrom are heard in the telephonic receiver, and by reason of this fact it is
possible not only to carry on telephonic conversations by means of wires attached
to the posts carrying the telegraph wires, when the latter are only traversed by
gradual currents, but also to carry on such conversations by means of the said
telegraphic wires.
с
In fact assuming that, in order to avoid telephonic induction, the wires of one
line are coupled two and two, each couple forming, relatively to the other wires of
the same line, a symmetrical system as perfect as possible. Then, in order to
utilize for the transmission of spoken messages, a couple consisting of two telegraph
wires; or in order to utilize for telegraphy a couple consisting of two ordinary
telephone wires transmitting spoken messages, I have recourse to one or the other
of the following arrangements, viz:
First Arrangement in which each double wire system furnishes a communication
for speech and a single telegraphic communication.
Let L, and L. (Figure 4) be the two wires of a couple; A₁, A, A, three electro-
magnets of about 500 ohms resistance, the two first occupying the two sides of a
Wheatstone bridge, and the third being interposed between the battery P and the
manipulator M; R the receiver of a telegraphic installation M R P ; C₁, C, two
condensers of about half a microfarad intercalated with an ordinary telephonic
installation T upon the diagonal p, q of the Wheatstone bridge; and S a suitable
resistance placed either upon one of the two lines, or upon one of the sides of the
bridge, or upon each of the two lines. It will always be possible, by properly
regulating the resistance S, to cause the points p and q to be maintained at the
same potential for all currents emitted at M, or for all currents of equal intensity
caused to pass simultaneously in the same direction upon the two lines L, and L.
The telephone T will then not be influenced either by the telegraphic currents or
by the induced currents acting simultaneously upon the two lines L₁ and L. But
the telephonic conversation will be carried on by the double wire as if the telephonic
installation alone existed.
It is not indispensable that A₁, A₂ and A, should be electro-magnets, they may
be simple resistances each of about 500 ohms.
Le may be an artificial line reduced to a simple resistance S, connected on the
one hand with the point q and on the other hand with the earth t. A telephonic
communication and a telegraphic communication are thus obtained by means of a
single wire L₁.
Second arrangement in which each double wire system furnishes a communication
for speech and two telegraphic communications.
Let L, L (Figure 5) be the two wires of a couple; P₁ M, R₁ and P, M, R, two
telegraphic installations of any description, in which the receivers R₁, R₂ have
always a resistance not much less than 500 ohms; A₁, A₂, A., A, electro-magnets of
about 500 ohms resistance; C₁, C, condensers of about two microfarads; C, C₁ two
condensers of equal capacity, each of about half a microfarad; B₁ B, B, an induction
coil with three circuits, that is to say, two equivalent primary circuits B₁, B₂, which
terminate respectively at the earth t and at the condensers C, C₁; and a single
secondary circuit B, connected on the one hand to the earth t and on the other hand
to a telephonic wire La, upon which is placed an ordinary telephonic station T.
The induction coil B, B₂ B, will then form a differential system.
Third arrangement in which each double conductor furnishes two telegraphic
communications and one communication for speech.
This arrangement is illustrated in Figure 6, in which similar letters of reference
indicate similar instruments to those in the preceding Figures. The only condition
to be fulfilled in this case, as regards the value of the resistances, is that,

page_text: and it will be sufficient to fulfil this condition approximately if S and S, are electro-
magnets instead of simple resistances.
It will, moreover, be possible to place the differential coil with the telephonic
station upon the connection p, q, in the manner above indicated for the
connection p, q in Figure 5.
Fourth arrangement. In the above described arrangements it is assumed that
the two telegraph wires constituting the double conductor terminate on the one
hand and on the other hand in the two localities between which the telephone is to
be used; but this is not indispensable.
In fact let L, L, (Figure 7) be two telegraph wires attached to any kind of
telegraphic installations, whatever may be their origin and destination, but parallel
between the localities O and V. The latter will be in telephonic communication by
means of the arrangement shewn in Figure 7, in which A, A, A, A, are electro-
magnets of at least 500 ohms resistance; C₁, C, C C condensers of half a
microfarad; C, C₁, C7, C, condensers of two microfarads; and T₁, T₁, two ordinary
telephonic stations, or by preference the installation shewn upon the connection p, q,
in Figure 5.
The differential coil B, B, B, Figure 5, may be advantageously constructed in
the following manner, illustrated in Figure 8, in which N is a soft iron core upon
which is wound the secondary circuit B. Upon this secondary coil and capable of
sliding thereon are the two equivalent primary coils B₁, B₁. It will be possible,
even if the latter are not identical, to cause them to exert upon B, an equivalent
action, by placing them in a suitable position relatively to B. t, t₂, T, L₁, and Le
are terminals connected as follows, that is to say, T with the telephonic station;
t, and to with the earth; L, and L. with the two telegraph lines by the medium of
condensers.
This differential system may be also constructed in another manner indicated in
Figure 9.
Two ordinary induction coils, identical with each other, are placed perpendicularly
to one another and coupled in the following manner, that is to say, the primary
circuits B₁, B, connected for quantity and the secondary circuits D₁, D, connected
for tension, and the terminals connected respectively, T with the telephonic station;
t₁ to with the earth; L and L with the two telegraph wires by the medium of
condensers. The soft iron cores N₁, N, are moreover, movable, that is to say, they
can be inserted more or less into the coils. It is possible, even if the two coils are
not identical, to cause them to exert an equivalent action and thus constitute a perfect
differential system. Or, if the coils are identical, but the two-line-wires employed
are not so, the injurious influence of telephonic induction can nevertheless be
obviated by a suitable regulation of the cores.
When telephonic induction is not to be taken into consideration, telegrams and
spoken messages can be transmitted by a single wire, by adopting the arrangement
above described at the end of the description of the first arrangement ("L₂ may be
an artificial line & ") or by employing the arrangement hereinafter set forth.
Fifth arrangement (Figure 10). M. is the manipulator, P the battery and R the
receiver of the telegraph station, the electro-magnet of which receiver must not
have a resistance much less than 500 ohms; A, A, are two electro-magnets of
about 500 ohms resistance; C¹ is a condenser of two microfarads; C₂ is a condenser
of half a micropharad.; and T is an ordinary telephonic station for receiving and
transmitting speech.
When it is only required to transmit speech to short distances, the existing
microphonic installations of Blake, Ader or others actuated by one or more
Leclanchè or Daniell elements will answer the purpose. But when it is required
to transmit speech to great distances, it is important to introduce at the
microphonic station the following improvement, the principle of which I will now
proceed to describe.
When the microphone is used with an induction coil, the induced currents
proceed from the variations in the intensity of the inducing current, and these.
variations are caused by the variations in the resistance which the imperfect

page_text: contacts of the microphone oppose to the passage of the current. I have found
that, other things being equal, the less the total resistance of the circuit, the
greater is the relative value of these variations in the resistance of the contacts
and the more considerable are the variations in the current which result therefrom.
In fact, let E be the electro motive force of the battery of the microphone; R₁ the 5
resistance of the said battery; R, the mean resistance of the microphonic contacts;
S the constant sum of all the other resistances; and I the intensity of the
micronhonic currents: then
Rt R₂S
(RRS)
It will be seen that d I has its maximum value when R₁
= 0.
It is necessary, therefore, to employ for producing the inducing current, an
electromotive source with an extremely feeble internal resistance. Secondary
batteries or accumulators and thermo-electric piles being such sources, their
application to the microphone, and in general the employment of any battery with
a very feeble internal resistance, is an improvement.
Figure 11 shews clearly how I effect this application. H is a secondary battery
or accumulator or a thermo-electric pile, K is the microphone, B an induction coil,
L the line and t the earth.
I have found, moreover, that to gain from this application all the advantages
which it is capable of affording, it is necessary (a) to employ a microphone with a
very feeble resistance, for example a microphone with multiple contacts all
arranged in quantity as indicated in Figure 12 (which shows a microphone with
8 parallel series, the total resistance of which does not exceed 2 ohms; whilst the
microphone with two contacts shewn in Figure 11 offers a resistance of about
16 ohms; (b) to give to the primary circuit of the coil B very little resistance.
For example with the microphone shewn in Figure 12 the resistance should not
exceed 0.2 ohm,
The condensers which I employ for my system are comparatively costly
instruments and are liable to be destroyed by two strong charges, whether these
charges proceed from telegraphy or from atmospheric or terrestrial electricity. In
order to protect them from such accidents, I combine each comparatively costly
condenser with another condenser of comparatively insignificant value and less
capable than the costly condenser of resisting strong charges. My preservative
apparatus is formed of two small metal plates well straightened, separated by one
or more sheets of paper, or other insulating material, by preference a material
capable of carbonization, but in any case of suitable thickness. It is, therefore, a
veritable condenser with a small surface. The di-electric interposed between the
two metal plates of the preservative condenser should be sufficiently thin to offer
to the electric charge less resistance than the insulating sheets which separate from
each other the metal plates of the condenser to be preserved. Each terminal of
the latter condenser must be connected to the corresponding terminal of the
preservative condenser.
It is clear that if, at a given moment, the line to which these two condensers are
connected receives too strong a charge, this charge will pierce the slightly resisting
preservative condenser before piercing the condenser having the higher resistance.
Moreover as soon as the preservative condenser is pierced, and its paper thus
carbonized at one or more points, it will form a good conductor for the remainder
of the charge, thus preserving the other condenser by conduction. To ensure the
attainment of the latter result, two very thin sheets of tin or fusible alloy
separated by one or more sheets of paper may be placed between the metal plates
of the preservative condenser. Then under the influence of a strong charge such
as might be produced by a flash of lightning not only will the paper be carbonized,
but the tin or alloy will be melted and will cause a metallic conductibility between
the two plates of the preservative condenser. It is evident that after each
accident of this kind, the paper and tin or fusible alloy must be replaced.
1
1

page_text: Having thus fully described the said invention as communicated to me by my
foreign Correspondent and the manner of performing the same I wish it
understood that I claim ;-
First. The herein described method which consists in rendering telegraphic
currents (whether primary, induced or derived) inaudible or imperceptible in a
telephone, by making the said currents gradual.
Second. The combination, at each telegraphic transmitting station, of a
manipulator with a current-graduator, in order to render the currents emitted by
the said manipulator inaudible in a telephone,
&
Third. The combination, at each telegraphic transmitting station, of
manipulator with two or more electro-magnets arranged one behind another with
condensers placed in derived or branch circuits between them.
Fourth. A combination of a successive series of condensers, in derived or branch
circuits between the line and the earth, with increasing resistances between the
said line or between the earth and each of the said condensers.
Fifth. The combination of one or more telephone wires with any number of
telegraph wires attached to the same posts, and provided at each transmitting
station with a current graduator.
Sixth. The means above described for transmitting simultaneously, by the same
wire or wires, telegrams and spoken messages, comprising the combination, for this
purpose, of two telegraph wires with two condensers and two induction coils
coupled on a differential system in such a manner that one extremity of the
primary wire of each coil is in communication with the earth, the secondary
circuit being in communication with any telephone station, as above set forth.
Seventh. The above described method of augmenting the intensity of telephonic
currents generated by means of the induction coil of a microphone, which method
consists in reducing to a minimum all the resistances of the microphonic circuit,
especially those of the battery and of the microphone, the resistance of the
inducing circuit of the coil being kept suitably proportionate to the resistance of
the microphone.
Eighth. The combination, for augmenting telephonic currents, of a secondary
battery or accumulator, or a thermo-electric pile or other electro-motive source
having a feeble internal resistance, with a microphone and an induction coil.
Ninth. The combination, for augmenting telephonic currents, of an electro-
motive source having a feeble internal resistance, with (a) a microphone having
multiple contacts all arranged for quantity, and (b) an induction coil, the primary
circuit of which has a resistance not exceeding 0.2 ohm.
Tenth. The employment simultaneously of the methods and combinations
described in the preceding claiming clauses, to constitute a new system of
simultaneous telegraphy and telephony by the same wire or wires over very long
distances, as above described.
Eleventh. The combination of a comparatively costly condenser with a much
smaller condenser of comparatively insignificant value and with less resistance than
the first named condenser, so that it will serve as a preservative therefor,
substantially as set forth.
In witness whereof I the said Henry Harris Lake have hereunto set my hand
and seal this Twentieth day of May in the year of our Lord one thousand eight
hundred and eighty four
HENRY H. LAKE (L.S.)