IMPROVEMENTS IN TELEPHONIC APPARATUS
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by Nelson King Cherrill at the Office
of the Commissioners of Patents on the 4th March 1882.
_NELSON KING CHERRILL of Bedford Lodge Shortlands in the County of Kent
"IMPROVEMENTS IN TELEPHONIC APPARATUS."
My invention relates to methods of producing and utilizing what are called and
known among electricians as " undulatory" currents of Electricity and to applying the
same for the purpose of transmitting signals or sounds to a distant station by means
of a "line wire or other electrical conductor as is now commonly employed in
electric or Telephonic signals.
In this my invention for producing the undulatory currents needed for the
electrical conduction of sounds such as I wish to convey I depend upon certain
principles or laws of Electro magnetic induction or magneto electric induction, or
generally the interactions between conductors and magnets whether permanent
magnets or electro magnets, such as have not up to the present time been applied
to the production of such undulatory or variable currents as are needed for the
purpose named, and for the purpose specified, namely, the transmission of sound by
Electrical means to a distant station; although such principles and laws of the
interactions of conductors and magnets whether permanent magnets or electro
magnets are already well known and applied in various other ways and for other
purposes.
The principles or laws to which I refer are stated by many authorities and may
be referred to generally as follows. When a conductor of electricity forming part
of a closed circuit is moved in the neighbourhood of a magnet in any direction except
along a line of magnetic force a current of electricity will be produced, which current
will be greater or less in electro motive force according to the circumstances under
which it is produced; but under any given conditions in order to obtain the maximum
effect it is necessary that the conductor should cut the lines of magnetic force at
right angles, and that it should be as near as possible to the pole or poles of the
magnet,
My modes of applying these laws to the production of currents of a suitable
character for the transmission of sound by electrical means are numerous but the
following description will serve to show the general principle of their application.

page_text: Suppose a wire to be stretched in such a manner as to be free to vibrate and at the
same time to form part of a closed circuit, it is evident that if a magnet either
permanent or electro were so approached to the wire as to cause the latter when
vibrated, to cut the lines of magnetic force, a current would be developed in the
closed circuit, if the wire were vibrated under such conditions; for every time the
wire moved across the lines of magnetic force in one direction, a current would
move through the circuit in one direction and when, through the vibration of the
wire it moved across the lines of magnetic force in the opposite direction, a
current would be induced in the opposite direction in the circuit, and if in the
circuit a suitable receiving instrument be included it is further evident that the
currents would be recorded by causing them to produce corresponding inductive
or magnetic effects, as is well known; and it is further evident that if the said
stretched wire be at a tension that will enable it to vibrate in unison with or in
proportion to any musical or other sound that the vibrations so communicated to it
by such sound, will cause and regulate a series of electric currents whose intensity
and rapidity will be proportionate to the amplitude and velocity of the vibrations
and hence the means are here provided Whereby according to my invention
undulatory currents such as are needed for the telegraphic transmission of sound
are produced. The method above indicated though perhaps sufficient for illustrating
the principle is probably one of several imperfect methods for carrying that prin-
ciple into effect, as the electro motive force of a single wire vibrating in the manner
described would be but slight even under favourable conditions but the same
principle can be amplified and carried into effect in many other and various ways,
as by using more wires than one, or by causing the same wire to vibrate in more
places than one, or by folding bending curving twisting or winding the wire or part
or parts of it in such manner as to increase the electromotive force of the currents
developed in it always having regard to the principles above set forth, whether
exactly expressed in the words above used or indicated thereby. Nor is it necessary
to use only nor do I confine myself to wires or combinations of wires stretched, they
may be folded bent curved twisted or wound in helices or other shapes or forms and
suspended balanced or placed in any position in regard to the magnet or magnets
which may be either permanent or electro magnets or any combination of the two
provided that regard is had to the suitable relative positions of the arrangement so
as to produce suitable currents in the manner necessary to the end in view. Nor
do I confine myself to the use of wires as other conductors may be used alone or in
combination with wires.
In order to carry this my invention into effect I proceed (among many other ways)
in the following manner.
I form a flat spiral of wire which may be single double three or more fold the
same may be attached to a diaphragm in such manner that it will be free to vibrate
by the action of sound or it may be so constructed as to vibrate without a diaphragm
and I then so adjust the said diaphragm and wire that the said vibrations made be
made across the lines of magnetic force of either a permanent or electro magnet and
I use the currents generated in the said spiral coils for the purpose before mentioned
namely for transmitting the electrical impulses to a distant station for the purpose
of there actuating signals by electric or magnetic induction either by instruments
already known and used or by novel adaptations to be hereafter described or by
duplicates of the transmitting instruments.
Nor do I confine myself to using the currents generated by the means above
alluded to as currents used to actuate and work directly the line wire or electric
circuit through which the signals or sounds are to be conveyed as the same may be
used either to act inductively upon other circuits or to react upon themselves by
acting inductively upon the magnetism producing them or the principle well known
and applied in many so called "dynamo electric" machines or engines, or to work
in any combination or variation of these methods depending upon the particular
circumstances of the case.
Nor do I confine myself even to the generating of currents in the manner above

page_text: indicated as contradistinguished from regulating currents as I may send a current
through the wire or other conductor by a permanent or other battery or source of
electricity and apply the said laws or principles of inductive action to alter vary or
modify the current so used and I may apply the current so altered or modified in
and for any of the abovementioned purposes. And as regards the reception of the
currents produced by any of the means above referred to and their conversion into
audible sounds at the further or distant station of the line as also on any other
intermediate stations, I use these currents in the same manner as the currents
produced or regulated by any other instrument for the transmission of sound are
used, in instruments called and known as telephones or microphones or by the
adoption of various other devices such as the greater power or electro motive force
obtainable in the currents used will enable me to adopt as for instance in another
mode of carrying out this my invention. I use the said vibrations of the wire or
helix to actuate a sounding board or a diaphragm in such a manner as to produce
audible sounds.