Improvements relating to the Transmission of Electric Telegraph Signals without Connecting Wires.
Year: 1899

page_text: A
Date of Application, 26th Jan., 1899
0010
1000
1000
Improvements relating to the Transmission of Electric Telegraph
Signals without Connecting Wires.
I, FERDINAND BRAUN, of No. 1, Universität Strasse, at Strassburg, in the
Province of Alsace, German Empire, Professor and Doctor of Philosophy, do
hereby declare the nature of this invention to be as follows;
-
My invention relates to the transmission of electric signals without connecting
wires, and comprises the improvements hereinafter indicated.
The electrical vibrations may be classified into three groups.
The first group includes vibrations which are created by the relative mechanical
movement of magnets and coils. These may be called electromagnetic vibrations,
and are exemplified in the well known ordinary alternating currents, as
used for electric light and transmission of power. Their frequency will obviously
be limited by the physical conditions of machinery.
A second group of electrical vibrations has been investigated by Fedderssen,
and others, and these vibrations consist of oscillations which are produced by
the discharge of Leyden jars with or without induction coils in circuit. The
frequency of these oscillations is considerably higher than the frequency of the
electromagnetic vibrations above referred to.
Another group of vibrations is that first studied by the late Dr. Hertz, and
known now as Hertzian waves, and in the production of these the capacity in
the circuit is not produced by means of Leyden jars and special induction coils,
but the capacity and induction of ordinary conductors are used.
Hitherto the attention of inventors has been principally confined to Hertzian
waves for the transmission of signals between two circuits without the use of
connecting wires and one object has been to increase the frequency of these waves
as much as possible in order to obtain propagation in a line as straight as possible.
This is exemplified by the use of the Righi transmitter. For the transmission
of signals in this manner it is essential, however, that the transmitting and
receiving circuits should be, so to speak, visible to each other; as stated by Dr.
Hertz in one of his earlier papers concerning the transmission of electric waves.
and by Professor Slaby's experiments, it has been shewn that various material
objects, such as sails, smoke, trees, buildings and the like, interposed between.
the circuits, weaken or in some cases entirely prevent communication between
the same.
My invention is intended to obviate this inconvenience, and I do this by
making use of electrical oscillations belonging to the second group above men-
tioned, and which have only a small frequency compared with the frequencies
hitherto adopted. By this means, owing to the length of the waves, these latter
are able to pass through conductors if these are of moderate thickness only.
Furthermore, obstacles in the path of the waves will not project such sharply.
defined shadows, the waves passing round them in a manner similar to that in
which sound waves pass round obstacles. Another advantage in using slower

page_text: vibrations is that their potential and amplitude, and thereby the energy trans-
mitted is more easily increased. When the Hertzian waves are used there is a
certain length of spark which must not be exceeded if the circuit is required to
excite vibrations; otherwise the vibrations would be damped too much, the con-
straint of the system giving way gradually instead of suddenly, but this means
that the effective potential is limited, which if lower oscillations are used either
does not occur, or can be very easily avoided.
I have found by experiments that the oscillations produced by the discharge of
Leyden jars of usual size in a circuit having moderate self-induction, are very
convenient for the purpose of transmitting signals, and the experiments also shew
that with an equal expenditure of energy in the transmitting circuit it is pre-
ferable to use the slower vibrations.
Dated this 26th day of January 1899.
Improvements relating to the Transmission of Electric Telegraph
Signals without Connecting Wires.
I, FERDINAND BRAUN, Professor and Doctor of Philosophy, of No. 1, Universität
Strasse, Strassburg, in the Province of Alsace, German Empire, 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:-
My invention relates to the transmission of electric signals without connecting
wires, and comprises the improvements hereinafter indicated.
-
. The electrical vibrations may be classified into three groups.
The first group includes vibrations which are created by the relative mechanical
movement of magnets and coils. These may be called electromagnetic vibrations,
and are exemplified in the well known ordinary alternating currents, as
used for electric light and transmission of power. Their frequency will obviously
be limited by the physical conditions of machinery.
A second group of electrical vibrations has been investigated by Fedderssen,
and others, and these vibrations consist of oscillations which are produced by
the discharge of Leyden jars with or without induction coils in circuit. The
frequency of these oscillations is considerably higher than the frequency of the
electromagnetic vibrations above referred to.
Third group of vibrations is that first studied by the late Dr. Hertz, and
known now as Hertzian waves, and in the production of these the capacity in
the circuit is not produced by means of Leyden jars and special induction coils
but the capacity and induction of ordinary conductors are used.
Hitherto the attention of inventors has been principally confined to Hertzian
waves for the transmission of signals between two circuits without the use of
connecting wires and one object has been to increase the frequency of these waves
as much as possible in order to obtain propagation in a line as straight as possible.
This is exemplified by the use of the Righi transmitter. For the transmission
of signals in this manner it is essential, however, that the transmitting and
receiving circuits should be, so to speak, visible to each other as stated by Dr.
Hertz in one of his earlier papers concerning the transmission of electric waves,
and by Professor Slaby's experiments it has been shown that various material

page_text: objects, such as sails, smoke, trees, buildings and the like, interposed between
the circuits, weaken or in some cases entirely prevent communication between
the same.
My invention is partially intended to obviate this inconvenience, and I do this by
making use of electrical oscillations belonging to the second group above men-
tioned, and which have only a small frequency compared with the frequencies
hitherto adopted. By this means, owing to the length of the waves, these latter
are able to pass through conductors if these are of moderate thickness only.
Furthermore, obstacles in the path of the waves will not project such sharply
defined shadows, the waves passing round them in a manner similar to that in
which sound waves pass round obstacles. Another and perhaps even more im-
portant advantage in using slower vibrations is that their potential and amplitude,
and thereby the energy transmitted, is more easily increased. When the Hertzian
waves are used there is a certain length of spark which must not be exceeded if
the circuit is required to excite vibrations, otherwise the vibrations would be
damped too much, the constraint of the system giving way gradually instead of
suddenly, but this means that the effective potential is limited, which if slower
oscillations are used either does not occur or can be very easily avoided.
I have found by experiments that the oscillations produced by the discharge of
Leyden jars of usual size in a circuit having moderate self-induction, are very
convenient for the purpose of transmitting signals, and the experiments also shew
that with an equal expenditure of energy in the transmitting circuit it is pre-
ferable to use the slower vibrations.
The Leyden jar or whatever other apparatus used for the production of the
electric impulses is connected with the spark gap of a Rhumkorff apparatus or
a Wimshurst influence machine and provided with the well known vertical sending
wire preferably of considerable length. In the receiving station the ordinary
arrangement may also be used for the vertical receiving wire, the coherer, local
battery and signalling device, such as Morse or the like.
In order that the invention may be clearly understood I have shown in the
accompanying drawings by way of example some arrangements of circuits for
transmitting signals by means of the electric oscillations above described.
In Figure 1 a Leyden jar indicated at F has its inner and outer coatings con-
nected through the air gapa, a coil P of small self-induction being included in
the circuit. The inner coating is connected to the transmitting wire M. The
jar is charged in the usual manner by means of an influence machine, inductorium
or other suitable means.
In Figure 2 a secondary coil S is provided communicating with the transmitting
wire M so that the oscillatory currents in the coil l' are transformed into currents
at an increased potential.
In place of one jar two or more can be used connected in parallel or in
series. Figure 3 for example shews two jars arranged in series, or as commonly
called in "cascade."
Figure 4 shows an arrangement similar to Figure 3. but in which the current
is transformed, a secondary coil $ being connected with the transmitting wire M.
The invention is not limited to the precise arrangements or circuits shown in
the drawings, as these can be varied very considerably, and electrical oscillations
of a low frequency suitable for transmitting signals according to my invention
can be produced in various other ways.
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. The improvement in the transmission of electrical signals without connecting
wires, which consists in using electrical vibrations of comparatively low frequency,
such as are produced by the discharge of Leyden jars, either with or without
induction coils in circuit, substantially as described.

page_text: 2. For the system of wireless transmission of electrical signals the combination
with a transmitting device, consisting of a spark producer, condensers and vertical
sending wire, of a receiving device, consisting of a receiving wire, local battery,
coherer and signalling apparatus, substantially as described.
Dated the 23rd day of October 1899.
W. P. THOMPSON & Co.,
Of London, Liverpool, Manchester, and Birmingham.