IMPROVEMENTS IN ELECTRO-MAGNETS FOR TELEPHONIC AND OTHER PURPOSES
Year: 1881

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LETTERS PATENT to John Imray, of No. 28, Southampton Buildings, Chancery
Lane, in the County of Middlesex, for an Invention of IMPROVEMENTS IN
ELECTRO-MAGNETS FOR TELEPHONIC AND OTHER PURPOSES." A communi-
cation from abroad by J. Milton Stearns, junior, of the City of Brooklyn,
New York, United States of America.
PROVISIONAL SPECIFICATION left by the said John Imray at the Office
of the Commissioners of Patents on the 12th October 1881.
JOHN IMRAY, of No. 28, Southampton Buildings, Chancery Lane, in the County
of Middlesex. "IMPROVEMENTS IN ELECTRO-MAGNETS FOR TELEPHONIC AND OTHER
PURPOSES." [A communication from abroad by J. Milton Stearns, junior, of the
City of Brooklyn, New York, United States of America.]
It has been proposed to make electro magnets astatic or neutral, so as to render
them in great measure independent of extraneous electric currents, by making their
cores consist of several permanent magnets laid side by side with their opposite
poles next one another. This Invention relates to the construction and adjustment
of the astatic cores of electro magnets in such a manner that their armatures or
diaphragms are attracted whatever be the direction of the electric currents through
their coils, and to means of communicating telephonically through such a magnet
from a transmitter that is extraneous to the circuit in which the magnet is situated.
When no adjustment is required for the astatic core it consists of a simple bar
magnet bent at its middle so as to bring its two opposite poles nearly or closely
together. These two poles are then near their extremities enclosed within a coil of
insulated wire, or each may have on it a separate coil forming part of a circuit.
Electric currents of either direction being transmitted through this circuit will
cause the magnet to attract an armature or diaphragm presented to the poles.
For the purpose of adjustment each of the coils when they are separate may be
slid by adjusting screws nearer to or farther from the polar extremity. When
instead of making the core by bending one magnetic bar it consists of two or more

page_text: separate magnets placed side by side, each of those is provided with an adjusting
screw, by which it can be slid forwards or backwards, as the case may be, within a
stationary coil, and the coil itself may be adjusted nearer to or farther from the
polar extremity of the core. Also when the core consists of a single magnet bent
at its middle this may be made to act as a spring, and by means of a transverse
setting screw the polar extremities can be adjusted nearer to or farther from each
other. Electro magnets thus constructed may be employed for relays worked either
for constant or alternating currents, or for testing the presence of magnetic inductive
influences, or in induction coils. When employed in telephones, their poles may
be set very close to, or even in contact with, the diaphragm, beyond which a metal
ring may be fixed. In order to communicate telephonically from a transmitter
extraneous to a telephone circuit the following arrangement is adopted :-A bar
magnet is bent twice at right angles, so that the two polar members project per-
pendicularly from its middle portion. On each of the polar members is a coil of
fine wire which is in the telephonic circuit. On the middle part of the magnet
near its neutral point, but on one side thereof, is placed a coil of coarse wire which
is in the extraneous circuit of a transmitter and battery. When the transmitter is
used, the excitement of the latter coil by shifting the neutral point of the magnet
affects the coils thereon, so that receiving instruments connected to them by the line
wire are acted on.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Imray in the Great Seal Patent Office on the 11th April
1882.
JOHN IMRAY, of No. 28, Southampton Buildings, Chancery Lane, in the County
of Middlesex. "IMPROVEMENTS IN ELECTRO-MAGNETS FOR TELEPHONIC AND OTHER
PURPOSES." A communication from abroad by J. Milton Stearns, junior, of the
City of Brooklyn, New York, United States of America.
It has been proposed to make electro-magnets astatic or neutral, so as to render
them in great measure independent of extraneous electric currents, by making their
cores consist of several permanent magnets laid side by side with their opposite
poles next one another. This Invention relates to the construction and adjustment
of the astatic cores of electro-magnets in such a manner that their armatures or
diaphragms are attracted whatever be the direction of the electric currents through
their coils, and to means of communicating telephonically through such a magnet
from a transmitter that is extraneous to the circuit in which the magnet is situated,
When no adjustment is required for the astatic core, it consists of a simple bar
magnet bent at its middle so as to bring its two opposite poles nearly or closely
together. These two poles are then near their extremities enclosed within a coil of
insulated wire, or each may have on it a separate coil forming part of circuit.
Electric currents of either direction being transmitted through this circuit will
cause the magnet to attract an armature or diaphragm presented to the poles. For
the purpose of adjustment each of the coils when they are separate may be slid by
adjusting screws nearer to or farther from the polar extremity. When instead of
making the core by bending one magnetic bar, it consists of two or more separate
magnets placed side by side, each of these is provided with an adjusting screw by
which it can be slid forwards or backwards, as the case may be, within a stationary
coil, and the coil itself may be adjusted nearer to or farther from the polar
extremity of the core. Also when the core consists of a single magnet bent at its
middle, this may be made to act as a spring, and by means of a transverse setting
screw the polar extremities can be adjusted nearer to or farther from each other.
Electro magnets thus constructed may be employed for relays worked either by
constant or alternating currents, or for testing the presence of magnetic inductive
influences, or in induction coils. When employed in telephones, their poles may be set
very close to or even in contact with the diaphragm, beyond which a metal ring may
be fixed. In order to communicate telephonically from a transmitter extraneous to
a telephone circuit, the following arrangement is adopted-A bar magnet is bent
twice at right angles, so that the two polar members project perpendicularly from
its middle portion. On each of the polar members is a coil of fine wire which is in
the telephonic circuit. On the middle part of the magnet, near its neutral point,
but on one side thereof, is placed a coil of coarse wire which is in the extraneous
circuit of a transmitter and battery. When the transmitter is used the excitement
of the latter coil by shifting the neutral point of the magnet affects the coils
thereon, so that receiving instruments connected to them by the line wire are
acted on.
The accompanying Drawings, Figs. 1 to 14 inclusive, shew various constructions
according to this Invention of astatic electro-magnets for telephonic use; Fig. 1
shews a magnet of horse shoe kind with both its limbs encircled by the coil A ;
Fig. 2 shews two separate magnets laid side by side with opposite poles adjoining
each other; Fig. 3 shews a similar pair of magnets which may be separately
adjusted lengthwise by setting screws, and Fig. 4 shews them with a setting

page_text: screw B¹ for adjusting them laterally; Fig. 5 shews the pair of magnets adjustable
longitudinally to or from their armature; Fig. 6 shews the pair of magnets with
the coil arranged to slide longitudinally along them; Fig. 7 shews a pair of
magnets joined together, but leaving their poles projecting free beyond their junction,
over or near which the coil A is placed. The magnets may be separated by a
narrow space, as shewn in Fig. 8, and this space may be widened except near the
poles, as shewn in Fig. 9. Magnets thus separated may be adjusted longitudinally,
as shewn in Fig. 10; Fig. 11 shews a ring magnet with coils without cores
cemented to the polar ends, so as to project with their axes at right angles to the
polar ends. Such a magnet may have a lateral adjustment, as shewn in Fig. 12.
It may be made as a compound ring, as shewn in Fig. 13, with the coils A on its
inwardly projecting elbows. The coil may be on the heels of the magnets, as
shewn in Fig. 14. For communicating telephonically from a transmitter extraneous
to a telephone circuit, a magnet and its connections are arranged, as shewn in
Fig. 15. A is the magnet having its polar limbs projecting perpendicularly from
its middle. On these limbs are coils È of fine wire in the circuit of the telephonic
line L, L. On the middle part, but on one side of the neutral line of the magnet
is a coil C of coarse wire connected, as shewn, with a transmitter T and its
battery B. When the transmitter T is spoken to, the effect of the coil C is to shift
to and fro the neutral line of the magnet A, thus affecting the coils E, E, so that
receiving instruments connected to the line L, L', reproduce the articulate sounds
addressed to the transmitter T. It will be seen that in this arrangement there is
no direct electrical connection between the transmitting and the receiving
instruments, nor is there any direct electrical induction of the one circuit on the
other.
Having thus described the nature of the said Invention, and in what manner
the same is to be performed, as communicated to me by my foreign correspondent,
I claim,―
First. The several constructions of astatic magnets for telephonic purposes herein
described with reference to Figs. 1 to 14 inclusive.
Second. The arrangement herein described with reference to Fig. 15, for
effecting telephonic communication from a transmitting instrument extraneous to
the circuit of the receiving instruments.
In witness whereof, I, the said John Imray, have hereunto set my hand and
seal, this Eleventh day of April, in the year of our Lord One thousand
eight hundred and eighty-two.