Improvements in Syntonised Telegraphy without Line Wires.
Year: 1897

page_text: (The Amendments are shown in erased and italic type.)
Improvements in Syntonised Telegraphy without Line Wires.
I, OLIVER JOSEPH LODGE, D.Sc., F.R.S., of 2, Grove Park, Liverpool, in the
County of Lancaster, Professor of Physics, do hereby declare the nature of this
invention to be as follows:
The object of my invention is to enable an operator to transmit messages across
space to any one or more of a number of different individuals in various localities,
each of whom is provided with a suitably arranged receiver.
The method consists in utilising certain processes and apparatus for the
purpose of producing and detecting rapid electric oscillations, and in so arrang-
ing them that the excitation of a particular frequency of oscillation at the send-
ing station may cause a Morse or any other telegraphic instrument to respond
at a distant station, by reason of being associated, through a relay or otherwise,
with a subsidiary circuit actuated by electric oscillations of that same particular
frequency, or by some multiple or sub-multiple of that frequency. Another
distant station will similarly be made to receive messages by exciting at the
sending station alternations of a different frequency, and so on: and thus
individual messages can be transmitted to individual stations without disturbing
the receiving appliances at other stations which are tuned or timed or syntonised
to a different frequency. Each station will usually be provided with both send-
ing and receiving apparatus, and messages can travel simultaneously in opposite
or in cross directions without the least confusion or interference.
The sending apparatus consists of a suitable condenser or Leyden jar or other
electric capacity (large or small) charged by an electrical machine or induction
coil, or battery, or any other well known means, to some considerable potential,
and then discharged suddenly with a spark of any required length or shortness,
occurring between suitably arranged and prepared surfaces immersed in a gaseous
or a liquid medium or in wreuo or in ordinary air, through a wire or other
local circuit, or through the gas or water pipes of a town, or through any other
local conductors which may be convenient, having coils of wire inserted or
removed or shifted relatively to each other at will for the purpose of attaining
any desired frequency of electric oscillation. The frequency can be adjusted
either by varying the capacity of the condenser or jar or other conductor employed
as the charged body, on the one hand, or by varying the number and position
of coils or other portions of the discharge circuit, on the other. By means of
suitable keys I propose to change easily from one rate of oscillation to another,
and thus signal first to one station and then to another, using the appropriate
Г. -

page_text: key for each station, and manipulating it, or some other key or sending instru-
ment in conjunction with it, so as to evoke dots and dashes or any other of the
known forms of telegraphic signal at the desired station or set of stations.
The electric oscillations set up by a discharging jar have long been known to
science, and the fact that such oscillations excite at a certain distance electric
waves which travel through space and material bodies with the velocity of light
was demonstrated by Hertz in 1888. I propose to employ a special combination
of capacities with conductors or coils so arranged as to give electric oscillations
of any desired frequency, so arranged also as to enable the frequency to be
varied with ease and certainty, and so arranged that their effects may be trans-
mitted to a distance either through the air or through the ground or through
conductors present for other purposes or through any intervening medium what-
ever.
As a means of receiving or detecting those electric waves or oscillations, no
matter whether the receiving station be within or beyond the distance at which
true simply-progressive waves arise, I propose to use an instrument based on
the "coherer" principle discovered by myself for metal in 1889, (Journal of the
Institute of Electrical Engineers Part 87 Vol. XIX, pages 352-354, re-printed
in Lightning Conductors and Guards" pp. 382 384) and by Lord Rayleigh
for liquids many years previously, and applied by Branly to the detection of
electric waves in 1890, (see my book on The Work of Hertz and some of his
successors PP 21-24.)
"
The coherer," for the purpose of this invention, depends on the property
which metals and liquids and other substances possess of uniting or cohering
more readily under slight electric influence than when brought into mere gentle
contact without such influence. Thus, at the delicately adjusted junction of
two metallic or other substances, a feeble electric current, such as is sufficient
to work a telegraphic relay, finds it easier to pass after the metals have been
subjected to the influence of electric oscillations, e.g. of any distant electric
spark or discharge, than before such influence. The original greater resistance
of the light contact can be restored by a slight mechanical vibration or shock,
which can be maintained automatically by any convenient means, such as the
friction or percussion of clockwork, or electrical make and break, or any other
shaking or trembling mechanism, as demonstrated by me before the British
Association at Oxford in 1894 in a communication entitled an electric eye and a
hypothesis concerning vision" (see the work of Hertz &c., page 27); or, as I
prefer in carrying out this invention, by means of a continuous sound, or sound
board, or by means of a coherer contact on a rotating disc or drum or other
moving surface; or in general any plan whereby metallic or other contacts are
established or improved by electrical means and broken or impaired by mechanical
means and whether these contacts be in air or any other medium, including
vacuum.
..
I have also shown a pair of syntonised electric circuits, whereby electrical
oscillations set up in the one are able to cause another to respond only when it is
exactly "tuned to the same frequency of vibration; a very slight change in
either the capacity or the self-induction of either circuit being sufficient to throw
the correspondence out. This exactitude or approximate exactitude of response
depends on the fact that the total number of oscillations in a suitably arranged
circuit is very great, so that a very feeble impulse is gradually strengthened
until it causes a perceptible effect, on the well known principle of sympathetic
resonance, See Modern Views of Electricity pages 338-340, or Nature Vol. XL.
p. 368, 1890, also my book on the work of Hertz &c., pages 5 and 7.
In carrying out this invention, I propose to associate with a coherer as above
described such a definitely adjusted electric circuit, to the end that the electric
oscillations purposely excited at a distant station in another syntonised circuit
may excite in the first one a response sufficient to disturb and temporarily alter
the resistance of the coherer associated with it, so as to enable the current of a

page_text: local cell or battery to pass more easily, and thereby to give any required
telegraphic signal, whether by means of a relay and auxiliary battery or other-
wise. There will thus be a pair of syntonised circuits, one associated with a
condenser and used as transmitter, the other associated with a coherer and used
as receiver.
The ordinary Hertz vibrator, and still more the radiating spheres which I
have myself heretofore employed with a receiving coherer, are powerful radiators,
but the vibrations are for this very reason so rapidly damped that no precision
of tuning is possible; and therefore such apparatus if employed in a system of
telegraphy depending on Hertzian waves is liable to disturb all receivers within
range, instead of an intended selection of them. But if, as in the arrangement
I employ in carrying out this invention, the radiator be partially enclosed in a
metallic box or cylinder of any shape, or if an arrangement of more electro-
static capacity be employed, then although the radiation becomes less powerful,
the total number of swings is so much increased that it may be made as ultimately
effective at a distance as the single powerful swing; and it has the advantage of
permitting precise tuning or syntonising, so that any desired one of a number
of receivers may be affected and not any of the others. Part of this invention
consists therefore in an arrangement whereby this desideratum becomes prac-
tically possible, as already explained, on the principles here laid down.
Dated this 8th day of May, 1897.
WM. P: THOMPSON & Co..
Of 6, Lord Street, Liverpool,
Patent Agents for the Applicant.
Improvements in Syntonised Telegraphy without Line Wires.
T, OLIVER JOSEPH LODGE, D.Sc., F.R.S., of 2, Grove Park, Liverpool, in the
County of Lancaster, Professor of Physics, do hereby declare the nature of this
invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:
The object of my invention is to enable an operator by means of what is now
known as Hertzian wave telegraphy, to transmit messages across space to any
selected one or more of a number of different individuals in various localities
each of whom is provided with a suitably arranged receiver, and to effect the
ancillary improvements the nature of which are indicated in my Provisional
Specification and are hereafter more particularly described.
The method of intercommunication consists, according to my invention, in
utilising certain processes and apparatus for the purpose of producing and detect-
ing a sufficiently prolonged series of rapid electric oscillations and in so arrang-
ing them that the excitation of a particular frequency of oscillation at the sending
station may cause a telegraphic instrument to respond at a distant station, by
reason of being associated, through a relay or otherwise, with a subsidiary circuit
capable of electric oscillations of that same particular frequency, or of some
multiple or sub-multiple of that frequency. Another distant station will
similarly be made to receive messages by exciting at the sending stations
alternations of a different frequency, and so on; and thus individual messages
can be transmitted to individual stations without disturbing the receiving
appliances at other stations which are tuned, or timed, or syntonised, to a
different frequency. Each station will usually be provided with both sending
and receiving apparatus..

page_text: '
In the accompanying drawings which are diagrammatic representations,
Figure 1 shows the simplest arrangement of emitter and receiver heretofore in
use;
Figures 2, 4, 6, 7, 8, 9 and 10 show alternative arrangements to be adopted at
signalling stations or appendages thereto in accordance with my invention;
Figure 3 in addition to showing an emitter serves to show a receiving circuit
and means whereby parts of the emitting arrangement is utilised for receiving
purposes;
Figure 5 depicts the more prominent features of a long distance arrangement,
both sending and receiving;
Figure 12 illustrates a form of "coherer" made in accordance with my inven-
tion;
Figures 13 and 14 illustrate alternative forms of connection of apparatus in a
syntonic receiving circuit with appendages; and
Figure 11 is a detail view hereinafter more particularly referred to.
Like letters of reference indicate similar parts throughout the drawings.
A complete installation of Hertzian wave telegraphy consists, in its simplest
form, of the arrangement depicted in Figure 1 wherein A represents the emitting
apparatus and B the receiving apparatus.
In the emitter illustrated in Figure 1, electricity from a suitable source, such
as a Ruhmkorff coil a, is supplied to a pair of conductors which discharge into
each other from knobs b and c and thus excite oscillations which emit one or two
waves before they are damped out.
The receiving circuit consists essentially of a collector 1, a coherer, e, a.
battery f, or other suitable source of electrical energy, and a telegraphic receiv-
ing instrument 9, all in electrical connection as shown.
In carrying out my invention and referring now to the subsequent figures of
the drawings, I use a definite radiator, consisting of a conductor, or pair of
conductors of large capacity arranged either as a Leyden jar or preferably
spread out separately in space (one of them being the earth when desired). I
join to and respectively (which I denominate "capacity areas") a pair of
polished knobs 2 h³ (protected by glass from ultra violet light) which form the
adjustable spark gap called the "discharge gap." Between either capacity area
and its knob I place a syntonising self inductance coil that is a coil of wire or
metallic ribbon, preferably insulated with any solid or fluid insulator, as in
Figure 2, or in air, of shape suitable to attain greatest inductance with a given
amount of resistance; the object of this coil being to prolong the electric
oscillations occurring in the radiator, so as to constitute it a radiator of definite
frequency or pitch, and obtain a succession of true waves emitted, and thereby to
render syntony in a receiver possible, because exactitude of response depends on
the fact that the total number of oscillations in a suitably arranged circuit is very
great, so that a very feeble impulse is gradually strengthened till it causes a
perceptible effect, on the well known principle of sympathetic resonance.
I supply the electricity to the radiator from a Ruhmkorff or a Tesla coil or a
Wimshurst or other known or suitable high tension machine a in one of three
wavs according to circumstances.
The first way is by leading wires from the machine a to the two discharge
knobs which is the customary plan, and gives a discharge which follows
upon fairly steady electric strain.
The second way consists, as shown in Figure 3, in having a supplementary
pair of spark gaps h h (which I call the supply gaps) one knob of each (called
the receiving knob) being attached to the middle or other convenient point of
each capacity area h¹ and the other knob of each pair (called the supply knob)
being connected by wires h to the Ruhnkorff coil a and brought moderately
near the first, so that when the coil is in action the capacity area shall receive
their positive and negative charge by aërial disruption, that is, in a sudden
manner, rather than by the slower process of metallic conduction, and shall then

page_text: be left to discharge into each other through the connecting coil h and across
the short spark gap between the knobs h³ ³. The best width of this gap depends
upon circumstances, and it may be closed altogether without stopping the
action. The gap between the knobs h² h³ may be optionally closed by a shunt .
On the third plan as indicated in Figure 4, I interpose in each of the wires h8
leading from the Ruhmkorff coil a to the supply knobs a Leyden jar or other
suitable condenser j able to stand a high potential, so that the knobs are supplied
from the outer that is the uninsulated coat of each jar, while between the inner
coats or coil terminals I arrange a third spark gap called the starting gap, also
consisting of suitable knobs 10. The outer coats of the jars must not be
insulated from each other, and I usually join them by a self-inductance coil of
fairly thin wire k so as to permit thorough charging. When the, discharge
occurs, this wire acts as an alternative path or bye-pass, but does not prevent the
sparks at the supply gaps.
By both of the means described with reference to Figures 3 and 4, I charge the
two capacity areas hh, which together with the inductance coil between them
constitute the radiator by aerial disruption or impulsive rush. The advantage of
this is that charges so communicated are left to oscillate free from any disturb-
ance due to maintained connection with the source of electricity, and therefore
oscillate longer and more simply than when supplied by wires in the usual way:
moreover the capacity areas of a radiator are thus more conveniently employed
as the capacity areas of a receiver without need of disconnection.
The arrangement described with reference to Figure 4 illustrates most com-
pletely the method of charging the capacity areas with an impulsive rush.
The action is as follows:
The Ruhmkort machine a charges the jars j, whose outer coats are connected,
and discharges them at the starting gap h. This spark precipitates a discharge
at the supply gaps h7 18 and suddenly supplies the capacity areas with electric
charges, which then surge through the connecting coil (divided into two parts
in this figure) and spark into each other at the discharge gap between the
knobs. This last discharge is the chief agent in starting the oscillations
which are the cause of the emitted waves. But it is permissible in the arrange-
ments of Figures 3 and 4 to close this last gap when desired and so leave the
oscillations to be started by the sparks at the supply gaps only, whose knobs must
in that case be polished and protected from ultra-violet light so as to supply the
electric charge in as sudden a manner as possible.
As charged surfaces or capacity areas, spheres or square plates or any other
metal surfaces may be employed, but I prefer, for the purpose of combining low
resistance with great electrostatic capacity, cones or triangles or other such
diverging surfaces, with the vertices adjoining and their larger areas spreading
out into space. Or a single insulated surface may be used in conjunction with
the earth, the earth or conductors embedded in the earth constituting the other
oppositely charged surface. Radiation from an oscillator consisting of a pair of
capacity areas is greater in the equatorial than in the axial direction, and
accordingly, when sending in all directions is desired, it is well to arrange the
axis of the emitter vertical. Moreover, radiation polarised in a horizontal
plane, that is with its electric oscillations vertical, is less likely to be absorbed
during its passage over partially conducting earth or water. A pair of insulated
capacity areas arranged for long-distance-signalling is shown on the left hand
side of Figure 5.
with the earth acting as the
23 by a triangular sheet or
rapidly alternating currents:
Figure 6 shows a single insulated capacity area
other surface and leading up to the spark knobs
cone so as to afford good conductance even to
The wire h8 in this case leads to one terminal of the Ruhmkorff coil a, the other
terminal of which is taken to earth as shown. The capacity area h is insulated as
indicated at h¹º.

page_text: Figure 7 shows an arrangement which will catch the wind less, and with a
syntonising coil h*.
Figure 8 shows an insulated metal surface in the form of a roof h of a shed
or building which may be used as a capacity area, with suitable connection and
apparatus (not shown) for either emitting or receiving inside the little house 7.
The self-inductance coil, represented at ht in all applicable figures, is a coil of
highly conducting wire or ribbon well insulated by air or by some other medium
as already described or else covered to a sufficient thickness with insulating
material; and it may be either a flat coil enclosing a plane area and shaped so
as to have maximum self-inductance for a given resistance, or it may be a
cylindrical coil wound upon a finely subdivided iron core, as shown at m in
Figure 9, either ring-shaped or U-shaped or straight. The discharge knobs h³ ³
may be arranged at one end of such coil as shown in Figures 2, 3, 7 and 9, or the
coil may be in two halves with the knobs inserted in the middle at pleasure (see
Figures 4 and 5). Several such coils *** *** with their knobs 2 h h may,
as shown in Figure 10, be arranged for use with a single pair of capacity areas,
and any one of them may be brought into action by a suitable switch, so that the
desired frequency of vibration, or syntony with a particular distant station is
attained by replacing one coil by another; for the frequency can be adjusted
either by varying the capacity of the condenser or jar or other conductor employed
or the charged body, on the one hand, or by varying the number and position
of coils or other portion of the discharge circuit on the other. That discharger is
in action whose spark gap is allowed to operate, and a switch A B C can
determine which of a set of different coils shall be utilised for a given distant
station. Figure 11 illustrates the form of switch indicated in Figure 10.
A plan alternative to that described with reference to Figure 10 is to connect
the capacity areas through one pair of knobs and a single large coil of a con-
siderable number of turns, as shown in Figure 9, and to have keys or plugs, or
switches S and S2 whereby some of the spires or turns of the coil can be
shunted out of action, so that the whole or any smaller portion of the inductance
available may be used, in accordance with the correspondingly attuned receiver
at the particular station to which it is desired to signal. This arrangement may
be used either in lieu of, or in combination with, interchangeable inductance
coils such as shown in Figure 10; and in the latter case they are useful for
correcting slight errors in tuning, for any one station. Another plan, and one
well adapted to secure accurate tuning, is to arrange some or the whole of a
syntonising coil so that its parts may be made to approach or recede from one
another. This one I call an adjustable coil, the other I call replaceable or
interchangeable coils.
A receiver or resonator consists of a similar pair of capacity areas connected
by a similarly shaped conductor or self inductance coil, the whole constituting
an absorber arranged so as to have precisely the same natural frequency of
electrical vibration as the radiator in use at the corresponding emitting station,
but it must not have a spark gap such as h² h³, or if it have a spark gap the same
must be carefully closed or shunted or bridged across by a good short conductor,
for example, like Figure 11, before the arrangement can be properly used as a
receiver. Identically the same capacity areas and self-inductance coil can be
used at will either as emitter or as receiver, that is, either as radiator or as
absorber (see Figure 5) if it be convenient to do so, on condition that the
discharge" spark gap h² h³ of the radiator is perfectly closed. whenever acting
as receiver.
68
Thus referring to Figure 3 it will be seen that that diagram illustrates a
combined emitting and receiving apparatus. When in use as a radiator the gap
between the discharge knobs he h³ is left open. When utilised as a resonator the
said gap is closed by the shunt h,. (there supposed to be like Figure 11) and
the coherer e battery f and telegraphic receiving instrument 9 are connected

page_text: through a thin wire from each end of the coil (that is from each of the
capacity areas). If the Ruhmkorff machine a had been actually connected to
the capacity areas h h', as in Figure 2, then it must be detached and substituted
by the coherer circuit when a receiver is wanted, but if the charge was supplied
through supply gaps as in Figures 3 and 4 (and this is the best plan) then the
Ruhmkorff connections can be left unaltered, as it is no way then affects the
action of the resonator, provided always that the coil is not put into activity
while the receiving circuit is connected up.
A coherer consists of any arrangement which drops in resistance on receipt
of an electric impulse, and rises to its old resistance on being subjected to a
mechanical impulse such as a tremor or a tap.
A coherer circuit is any known arrangement for observing or recording effects
due to fluctuations in the electrical resistance of a coherer.
As coherer I may use Branly's arrangement of a pair of conductors embedded
in metallic grains or powder or filings, but I prefer selected iron filings of
uniform size sealed up in a good vacuum and with the communicating surfaces
or electrodes reduced to points or thin platinum wires fused into the glass and
with their ends close together. In lieu of a known coherer I may employ that
illustrated in Figure 12 wherein a point n rests lightly on a flat metallic surface »,
for instance a needle point of steel or platinum making light contact with a steel
or aluminium or other spring like a watch spring, straight or bent, usually
fixed at one end p and delicately adjustable by a thumb screw q at some other
part, so as to regulate the pressure which it exerts on the fixed needle point.
Whenever an electric wave or impulse from a distant radiator arrives and
stimulates electric vibrations in the syntonised resonator or absorber arranged
for the purpose, the delicately adjusted junction of the two metals or of the
metallic or other particles which are connected up to the resonator so as to feel
these vibrations suddenly and greatly changes its electrical resistance, and this
diminished resistance enables a local battery to actuate a relay or a telephone or
other telegraphic instrument in circuit therewith.
To break contact again, or to restore the original greater resistance, any form
of mechanical vibration suffices, and so on the stand of the coherer I mount
either a clock or a tuning fork or a cog-wheel or other device for causing a shake
or tremor of sufficient intensity, maintaining it in motion by either a spring or
weight or by electrical means. In Figure 12ands are two wheels of a clock-
work train. Upon the arbor (or on a disc mounted thereon) is a series of serra-
tions or the like t (shown exaggerated in the drawing) which as the wheel rotates
effects the vibration of the lever or spring o. Such a tapper as is used in
dentistry likewise serves very well. Or the mere motion of any clockwork
attached to the stand will suffice. An exceedingly slight, almost imperceptible.
tremor is all that is usually needed.
The diminution of resistance takes place instantaneously, and contact is broken
again in a very small fraction of a second later. The instant it is broken the
junction is ready to receive a fresh signal. The rapidity of signalling depends
on the quickness of response of the signalling instrument, and it depends also on
the rapidity with which the mechanical arrangement can break or interrupt the
cohesion directly after the electrical stimulus has established it.
phone is used I find that the coherer restores itself sufficiently without specially
When a tele-
arranged tremor and that a telephone is the quickest responder that can be used.
As coherer circuit, I usually arrange the coherer in simple series with a battery
(voltaic or thermal) and a galvanometer or other indicator or recorder of fluctua-
tions of current, and I then connect the terminals of this series of instruments
to the capacity areas of the receiver close to its self inductance coil, so that this
same coil of wire completes and forms an essential part of the coherer circuit.
The coherer is thus affected by every electrical disturbance occurring in the
connecting coil or in its capacity areas, and by aid of the battery at once enables
the telegraphic or telephonic instrument to appreciate and indicate the signals,

page_text: This plan is shown in Figure 13. It is an improvement on any mode of con-
nection that had previously been possible without the connecting coil.
In some cases I may, as shown in Figure 14, surround the syntonising coil of
the resonator with another or secondary coil (constituting a species of trans-
former) and make this latter coil part of the coherer circuit, so that it shall
be secondarily affected by the alternating currents excited in the conductor of the
resonator, and thus the coherer be stimulated by the current in this secondary
coil rather than primarily by the currents in the syntonising coil itself; the idea
being thus to leave the resonator freer to vibrate electrically without disturbance
from attached wires.
In all cases it is permissible and sometimes desirable to shunt the coils of the
telegraphic instrument by means of a fine wire or other non-inductive resistance,
as shown at w in Figure 13, in order to connect the coherer more effectively
and closely to the capacity areas or receiving arrangement whereby it is to be
stimulated..
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:
1. In a system of Hertzian wave telegraphy, the combination with a pair of
capacity areas (of which one may be the earth) of a self-inductance coil inserted
between them electrically, for the purpose of prolonging any electrical oscilla-
tions excited in the system, and constituting such a system a radiator of definite
frequency or pitch.
2. In a system of Hertzian wave telegraphy, the combination with a pair of
capacity areas (of which one may be the earth), of a self-inductance coil inserted
between them electrically for the purpose of prolonging any electrical oscilla-
tions excited in the system and thereby enabling a distant radiator to act
cumulatively if of corresponding period; thus constituting the system a
resonator or absorber of definite frequency or pitch.
3. In-a-system-of Hertzian-wave-telegraphy, the combination-with-a-pair-of
enpacity areas (one-of-which-may-be the earth) of means-inserted between them
electrically-serving to syntonise them and to render them-adaptable-for-use-nt-will
either-as-n-radiator or resonator.
4. In a system of Hertzian-wave-telegraphy, the combination with a pair of
eapneit-urens fone-of-which-may-be-the-earth), of-n-number of self inductance coils,
ench-of-which is capable of being switched in-or-out-of-circuit-so-as-to-furnish
different amounts of self-induction, thus serving to cyntonise each radiator-to-a
corresponding resonator or vice versa, whereby signalling may be effected between
any two or more correspondingly-attuned-stations without disturbing other differ-
ently attuned stations.
In-a-system-of Hertzian wave telegraphy; the combination-with-a-pair-of
enpreity areas (one of which may be the earth) of an adjustable self-inductance coil
adjustable either by definite-steps or by continuous-motion of its-parts-serving-to
syntonise such radiator and resonater to each other-whereby-signalling-may-be
effected between-any two or more correspondingly attuned stations without disturb-
ing other differently attuned stations.
8. In combination, a pair of capacity areas connected by a coil of wire
serving as the radiator in a system of Hertzian wave telegraphy, means for
syntonising such radiator and means for charging it by aërial disruption or
impulsive rush.
4. In a system of Hertzian wave telegraphy, the combination of a pair of
capacity areas such as h h¹, means for syntonising such capacity areas, a receiv-
ing circuit completed through one or both of such capacity areas
or their
adjuncts, and means for bridging over the discharge gap between such capacity
areas when they are to be used as a receiver whereby such capacity areas are
rendered adaptable for use at will either as a radiator or resonator.

page_text: 8. A coherer comprising a needle-point resting upon a flat metallic surfaces
means for regulating the pressure of the one upon the other, and means for pro
ducing a mechanical impulse or tremor therein after it has received an electries
impulse substantially as and for the purpose set forth and as illustrated in the
accompanying drawing.
5. In a system of syntonie Hertzian wave telegraphy the combination with
the self-inductance coil of the receiver of a secondary coil surrounding the same,
which secondary coil forms part of the coherer circuit substantially as and for
the purpose set forth.
6. 10 The combination, in the receiving circuit of a system of Hertzian
wave telegraphy, of an adjustable or replaceable self-inductance coil, connecting
the capacity areas, a coherer, a battery, a telegraphic receiving instrument or
a telephone with or without a shunt across the coils thereof substantially as and
for the purpose set forth.
7. The construction arrangement and combination of parts constituting
my improved system of syntonic Hertzian wave telegraphy substantially as set
forth and as illustrated in the accompanying drawings.
Dated this let dow of Fahru
1908
WM. P. THOMPSON & Co.,
Patent Agents,
Of Liverpool, Manchester, Birmingham & London,