IMPROVEMENTS IN AND RELATING TO MAGNETS AND TELEPHONES AND COMBINATIONS OF MAGNETS WITH TELEPHONES
Year: 1880

page_text: LETTERS PATENT to Frederick John Cheesbrough, of the Office for Patents,
15, Water Street, Liverpool, in the County of Lancaster, Consulting Engineer,
for an Invention of "IMPROVEMENTS IN AND RELATING TO MAGNETS AND
TELEPHONES AND COMBINATIONS OF MAGNETS WITH TELEPHONES." A commu-
nication from abroad by Asabel Knowlton Eaton, of the City of Brooklyn, in
the County of Kings, State of New York, United States of America, Chemist
and Electrician.
PROVISIONAL SPECIFICATION left by the said Frederick John Cheesbrough
at the Office of the Commissioners of Patents on the 20th February 1880.
FREDERICK JOIN CHEESBROUGH, of the Office for Patents, 15, Water Street,
"IMPROVEMENTS IN
Liverpool, in the County of Lancaster, Consulting Engineer.
AND RELATING TO MAGNETS AND TELEPHONES AND COMBINATIONS OF MAGNETS
WITH TELEPHONES." [A communication from abroad by Asahel Knowlton Eaton,
of the City of Brooklyn, in the County of Kings, State of New York, United States
of America, Chemist and Electrician.]
This Invention consists,-
First. Of a multipolar magnet, either permanent or temporary, constructed in
such manner that two or more similar poles will re-act with one of an opposite
character, the latter being the equivalent of all the others.
Second. Of the application of a multipolar magnet, consisting of a central com-
pound bar, around which are uniformly distributed a number of smaller bars which
are branches of the former, and of an opposite polarity to the diaphragm plate of
the telephonic transmitter and receiver for the purpose of increasing and distributing
the magnet action upon and over the plate.
Third. Of the application of a series of slender sheet steel U shape magnets to
the diaphragm of the receiving telephone to act in conjunction with the outer
poles of the multipolar magnets for the purpose of obtaining greater sensitiveness
in the plate.
Fourth. Of increasing the elasticity of the telephone plate without increasing its
thickness by means of one or more corrugations made upon or in the plate.
Fifth. Of a combination of two or more diaphragm plates, either plain or corru-
gated, and separated by a ring of cardboard interposed between them near their
edges so as to inclose a film of air, the plates being cemented to the card board to
prevent the escape of the air, the object being to make the air act as a cushion in
transmitting the vibrations from plate to plate. '
The aforesaid multipolar magnet consists of a piece of magnetized steel, in which

page_text: the central bar indicates, say, the north pole, and the others two poles of half the
size of the former and of the opposite polarity, i.e, two south poles that just balance
the single central pole.
Upon the same principle multipolar magnets may be constructed having three,
four, six, or more poles of a given polarity balancing one of the opposite
character.
These forms of magnets are of great value, not only in the production of greater
and simpler magnetic effects than can be produced by the ordinary magnet of
corresponding size, but also because magneto-electric currents can be induced and
utilized much more effectually than by any form of magnet hitherto in use.
It is evident that any required number of small poles of similar character may
be similarly combined with and symmetrically arranged around an equivalent single
pole of the opposite kind.
In making use of this magnet in the organization and construction of a telephone
the central bar of the magnet is the north pole at its upper extremity, and the
free ends of the smaller ones are all south poles when inagnetized.
Upon the
different poles of this magnet induction coils are fixed proportioned to their magnetic
power.
By the use of this form of magnet in a telephone there is obtained not only a
more powerful magnet action, but there is also obtained a better and wider dis-
tribution of that action over a considerable portion of the plate instead of confining
it to the centre, as heretofore, by which plates of much larger diameter can be
used, thereby gaining in loudness of tone without loss of distinctness of
articulation.
The number of smaller poles used to balance the larger ones may be greater or
less, it being only requisite that whatever the number the smaller poles be arranged
symmetrically around the larger.
The number, however, should vary with the diameter of the plates employed.
With a diaphragm of six inches diameter a group of twelve outer poles should be
employed to balance a corresponding central one, and the distance of the outer poles
from the central one should also vary with the size of the plate.
To increase the elasticity of the telephone plate without increasing its thickness
there is made upon or in it one or more corrugations according to the diameter of
the plate, the number of corrugations increasing as the diameter of the plate
increases.
A single diaphragm plate may be used, but a compound plate is preferred con-
sisting of two or more single plates, either plain or corrugated, combined.
When a compound plate is used the plates composing it are separated by a ring
of card board or other suitable material interposed between them at or near their
edges, and upon which the plates are cemented or otherwise united with a tight
joint to retain the air, by which a thin layer of confined air is made to act as an
elastic cushion, preventing absolute contact, while at the same time it transmits the
vibrations from plate to plate.
In the receiving telephone a diaphragm of any sufficiently elastic, non magnetic,
or diamagnetic material, such as hard rubber, wood, card board, sheet brass, is
made use of, to which are cemented a number of slender sheet steel U shaped
magnets corresponding to the number of the outer poles of the multipolar magnet.
These are fixed symmetrically upon the diaphragm in such a manner that one
pole of each small magnet (that of the shorter leg) shall press upon one of the
outer poles of the multipolar magnet, and the others, fastened in a cluster upon
the centre of the disc, shall vibrate as a whole before the main pole of the multi-
polar magnet. In the use of this plate the small induction coils are dispensed with,
retaining the larger one only upon the central pole.
The object of this part of the Invention is to secure the greatest possible sensi-
tiveness in the plate of the receiver.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Frederick John Cheesbrough in the Great Seal Patent Office
on the 19th August 1880.
FREDERICK JOHN, CHEFSBROUGH, of the Office for Patents, 15, Water Street,
“IMPROVEMENTS IN
Liverpool, in the County of Lancaster, Consulting Engineer.
AND RELATING TO MAGNETS AND TELEPHONES AND COMBINATIONS OF MAGNETS
AND TELEPHONES." A communication from abroad by Asahel Knowlton Eaton, of
the City of Brooklyn, in the County of Kings, State of New York, United States
of America, Chemist and Electrician.
This Invention consists,―
First. Of a multipolar magnet, either permanent or temporary, constructed in
such a manner that two or more similar poles will re-act with one of an opposite
character, the latter being the equivalent of all the others.
Second. Of the application of a multipolar magnet consisting of a central com-
pound bar, around which are uniformly distributed a number of smaller bars which
are branches of the former, and of an opposite polarity to the diaphragm plate of
the telephonic transmitter and receiver for the purpose of increasing and distributing
the magnet action upon and over the plate.
Third. Of the application of a series of slender sheat steel U shaped magnets to
the diaphragm of the receiving telephone to act in conjunction with the outer poles
of the multipolar magnets for the purpose of obtaining greater sensitiveness in the
plate.
Fourth. Of increasing the elasticity of the telephone plate without increasing its
thickness by means of one or more corrugations made upon or in the plate.
Fifth. Of a combination of two or more diaphragm plates, either plain or corru-
gated, and separated by a ring of card board interposed between them near their
edges so as to enclose a film of air, the plates being cemented to the card board to
prevent the escape of the air, the object being to make the air act as a cushion in
transmitting the vibrations from plate to plate.
Reference being had to the accompanying Drawings, and to the figures and
letters of reference marked thereon,
The aforesaid multipolar magnet consists of a piece of magnetized steel, such as
represented by Figures 1 and 2 of the Drawings, in which the central bar A indi-
cates, say, the north pole, and B, B, two poles of half the size of the former, and
of the opposite polarity, i.c., two south poles that just balance the single central
pole.
Upon the same principle multipolar magnets may be constructed having three,
four, six, or more poles of a given polarity balancing one of the opposite
character.
The Drawings represent two of the more useful of the magnets.
One (repre-
sented by Figures 3 and 4) has four poles B, B, B, B, balancing a single pole A.
Figures 5 and 6 represent a magnet having six given poles B, B, Ẻ, B, B, B,
balanced by one single pole A of the opposite polarity.
These forms of magnets are of great value, not only in the production of greater
and simpler magnetic effects than can be produced by the ordinary magnet of
corresponding size, but also because magneto electric currents can be induced and
utilized much more effectually than by any form of magnet hitherto in use.
The magnet represented by Figures 5 and 6 is especially adapted to any work
when it becomes necessary to act upon an armature in the form of a circular
disc.
It is evident that any required number of small poles of similar character may
be similarly combined with and symetrically arranged around an equivalent single
pole of the opposite kind.

page_text: In making use of this magnet in the organization and construction of a telephone
the central bar of the magnet is the north pole at its' upper extremity, and the
free ends of the smaller ones are all south poles when inagnetized. Upon the
different poles of this magnet induction coils are fixed proportioned to their magnetic
power.
By Figure 8 of the Drawings is shown a plan of the magnet as it is applied in
telephones with the induction coils attached, as shown by i, i, i, i, i, i, and I. Tho
main central or north pole is marked + and the six small or south poles aro
marked -, or the reverse.
By the use of this form of magnet in a telephone there is obtained not only a
more powerful magnet action, but there is also obtained a better and wider dis-
tribution of that action over a considerable portion of the plate instead of confining
it to the centre, as heretofore, by which plates of much larger diameter can be used,
thereby gaining in loudness of tone without loss of distinctness of articulation.
The number of smaller poles used to balance the larger ones may be greater or
less than represented, it being only requisite that whatever the number the smaller
poles be arranged symmetrically around the larger.
The number, however, should vary with the diameter of the plate employed.
With a diaphragm of six inches diameter a group of twelve outer poles should
be employed to balanco a corresponding central one, and the distance of the outer
poles from the central ono should also vary with the size of the plate.
To increase the clasticity of the telephone plate without increasing its thickness
there is made upon or in it one or more corrugations a, according to the diameter
of the plate, the number of corrugations increasing as the diameter of the plate
increases.
A single diaphragm plate may be used, but a compound plate is preferred con-
sisting of two or more single plates, either plain or corrugated, combined.
When a compound plate is used the plates composing it are separated by a ring
of card board or other suitable material interposed between them at or near their
edges, and upon which the plates are cemented or otherwise united with a tight
joint to retain the air, by which a thin layer of confined air is made to act as an
elastic cushion, preventing absolute contact, while at the same time it transmits the
vibrations from plate to plato.
A plan of a single corrugated plate is shown by Figure 9, a section of the saine
plate is shown by H, Figure 11, and a section of the compound chambered plate
is shown by J, Figure 11.
In the receiving telephone a diaphragm of any sufficiently elastic, non magnetic,
or diamagnetic material, such as hard rubber, wood, card board, sheet brass, is
made use of, to which are cemented a number of slender sheet steel U shaped
magnets corresponding to the number of the outer poles of the multipolar magnet.
These are fixed symmetrically upon the diaphragm in such a manner that one pole
of each small magnet (that of the shorter leg) shall press upon one of the outer
poles of the multipolar magnet, and the others, fastened in a cluster upon the
centre of the disc, shall vibrate as a whole before the main pole of the multipolar
magnet. In the use of this plate the small induction coils are dispensed with,
retaining the larger one only upon the central pole.
The object of this part of the Invention is to secure the greatest possible sensi-
tiveness in the plate of the receiver.
The construction of this plate is represented in section by Figure 12, and in plan
by Figure 10, and the thin steel magnets by m, m, m.
Figure 7 represents the complete telephone in section showing the compound
plates of Figures 10, 11, and 12, with induction coils C, C, applied to the several
poles of the magnet; but the simplest form of the Invention is a combination of a
single plate, either plain or corrugated, with the multipolar magnet, fitted with one
induction coil around the central pole of the magnet.

page_text: What I claim as the Invention communicated to me by my foreign correspondent
is,-
First. A multipolar magnet consisting of one pole, either simple or compound, of
given polarity, balanced by two, three, or more poles of the opposite character,
distributed symmetrically with reference to the main pole and to one another.
Second. In combination with a telephone diaphragm plate a multipolar magnet
consisting of one pole of given polarity balanced by two, three, or more poles of
opposite character distributed symmetrically with reference to the main pole, the
wholo acting as one magnet, combined with one or more induction_coils, as set
forth.
Third. A telephonic diaphragm plate fitted with a series of thin sheet steel
U shaped magnets to act in conjunction with the outer poles of the multipolar
magnet for the purpose of obtaining greater sensitiveness in the plate, as set forth.
Fourth. A telephonic diaphragm plate made with one or more corrugations in its
surface for the purpose of increasing its elasticity without increasing its thickness,
as set forth.
Fifth. A compound diaphragm plate for telephones consisting of two or more
plates, either plain or corrugated, united at their edges upon rings interposed
between them with a tight joint, by which a film of air is enclosed between the
plates and made to act as an elastic transmitting cushion of the vibratious from
plate to plate.
Sixth. A compound vibrating plate for telephones consisting of a series of thin
U shaped magnets acting as one, attached to a non magnetic or diamagnetic
diaphragm, substantially as described.
In witness whereof, I, the said Frederick John Cheesbrough, have hereunto
set my hand and seal, this Eighteenth day of August, in the year of our
Lord One thousand eight hundred and eighty.