IMPROVEMENTS IN TELEPHONES
Year: 1879

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields, in the
County of Middlesex, Gentleman, for the Invention of "IMPROVEMENTS
IN TELEPHONES," A communication from abroad by Frédéric Allen Gower
and Cornelius Roosevelt, both of Paris, in the Republic of France.
Sealed the 4th April 1879, and dated the 30th January 1879.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson at the
Office of the Commissioners of Patents on the 30th January 1879.
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN TELEPHONES." A communication from abroad by
Frédéric Allen Gower and Cornelius Roosevelt, both of Paris, in the Republic of
France.
This Invention relates to certain improvements in the construction of telephones,
and it has for its object increasing the efficiency of these instruments whilst
enabling them to. be made in a more compact and convenient shape, and to be
readily combined with the apparatus for producing signals to attract attention, as
described in the Provisional Specification filed by me on the 3rd October 1878,
No. 3892.
According to one mode of carrying out this Invention telephones are constructed
with magnets of semi circular form with their two extremities bent inwards, so as
to converge towards the centre, and thus brought as near as possible to the centre of
the circular vibrating plate of the telephone. A semi circular orifice is formed in this
plate which, without in any way diminishing the efficiency of the apparatus, com-
municates with a tube containing a vibrating tongue attached to the underside of
the vibrating plate, so that by blowing into the mouthpiece of the telephone a
musical sound is produced and transmitted to the receiving apparatus, for the
purpose of attracting the attention of the person in charge, as described in the
Provisional Specification herein before referred to.
The magnet is contained in a flat circular case of wood (for example), having a
cover with an orifice in the centre, provided with a mouthpiece or a speaking tube
of any convenient form and length. This cover, which is attached to the sides of
the case by means of screws, carries the vibrating plate hereiubefore referred to, the
said plate being firmly secured to the cover by means of a flat ring of copper and
by screws. A hole is provided in the bottom of the case for the escape of the air
Duins C21

page_text: employed to cause the vibrations of the vibrating tongue herein before referred to,
-which-is.arranged-in-a-suitable-tube. The magnet fits into the bottom of the case
opposite to and parallel with the vibrating plate, and is provided with poles of soft
iron attached to the underside of its extremities by screws or otherwise, and bent
up-at-right-angles; the vertical part of which forms the magnetic cores of bobbins
carrying the wire, and forming the induction coils of the telephone; these bobbins
may be made of wood; copper, or any other suitable material, and vary in their
shape and dimensions according to the purposes to which the telephone is to be
applied.
.
The employment of a semi circular magnet of a form generally resembling that
herein described has the effect of bringing the poles of the magnet and the coils of
the telephone as near as possible to the centre of the vibrating plate or diaphragm,
a position which has been found by experience to be the most favorable to the
proper action of the said plate. The employment of a magnet of this form also has
the advantage of avoiding the objectionable influence of the two extremities upon
one another, which is always present when horseshoe magnets with nearly parallel
extremities are employed. Moreover, by employing magnets formed according to
this Invention, it becomes possible to effect a considerable reduction in the size of
the case of the telephone, and to avoid almost entirely the echo and resonance
occurring in the large cases required for containing a magnet of the ordinary horse-
shoe form.
It should also be observed that the shape of the magnets formed according to
this Invention has a tendency to concentrate towards the centre of the vibrating
plate all the sounds produced in the case, either by the employment of pneumatic
signals produced by the vibrating tongue hereinbefore referred to, or by the vibra-
tions produced in the telephone when employed as a receiver. This form of magnet
also has the advantage of admitting of the employment of a vibrating plate of
larger diameter than those ordinarily employed, and so considerably auginenting the
power and efficiency of the apparatus. The effect obtained is also increased in
consequence of the entire power of the poles of the magnet being concentrated at
a single point on the vibrating plate.
An important detail of construction consists in the arrangement of the orifice in
the centre of the cover, which is provided with a short brass tube, one end of which
is screwed into said orifice, whilst the protruding portion, which is of larger
diameter, is inserted into one extremity of a flexible tube of convenient length in
such a manner that when the telephone is placed upon a table or other suitable
support, or hung on a wall by a ring attached to the case, any person desirous of
making use of it can do so without the necessity of applying his mouth directly to
the orifice above the vibrating plate.
In order to prevent the flexible tube from wearing out rapidly, the brass tube is
caused to enter its extremity for a certain distance, so as to afford the required
support at the part most liable to be strained, and the other end of the flexible tube
is provided with a mouth piece of such form as to afford facility for speaking, and
to direct the current of air blown into it by the person using the apparatus in the
most advantageous manner, for the purpose of acting upon the vibrating tongue or
other musical instrument employed for producing the signal to call attention, and
enabling it to emit the required sound.
According to another mode of constructing the magnet, the converging poles are
arranged in the same plane as the extremities of the magnet, which in this instance
is placed at right angles to the vibrating plate, this form is more particularly adapted
for receiving battery currents and converting them into audible sounds. The
extremities of the magnet converge towards the centre of the vibrating plate, being
prolonged by poles attached to the said extremities by screws or other-wise. The
wires forming the induction coils of the telephone are coiled round these prolonga-
tions, which form magnetic cores; these coils may be formed on bobbins constructed a
as herein before described, or in any other suitable manner. By this arrangement

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Henry Johnson in the Great Seal Patent Office on the luth
July 1879.
"
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. IMPROVEMENTS IN TELEPHONES." A communication from abroad
by Frédéric Allen Gower and Cornelius Roosevelt, both of Paris, in the Republic of
France.
The said Invention relates to certain improvements in the construction of
telephones, and it has for its object increasing the efficiency of these instruments
whilst enabling them to be made in a more compact and convenient shape, and to
be readily combined with the apparatus for producing signals to attract attention,
as described in the Specification to former Letters Patent granted to me, and dated
the Third October, One thousand eight hundred and seventy eight, No. 3892.
And in order that the said Invention may be fully understood, I shall now
proceed more particularly to describe the same, and for that purpose shall refer to
the several Figures on the annexed Sheet of Drawings, luc same letters of reference
indicating corresponding parts in all the Figures.
Figure 1 of the accompanying Drawings represents a sectional plan of a telephone
constructed according to the said Invention, the section being taken along the line
1, 2, in Figure 2. Figure 2 is a transverse section of the telephone taken along the
line 2, 3, 4, Figure 1. Figure 3 is sectional plan of the apparatus viewed from...
below the section, being likewise taken along the line 1, 2, Figure 2, and Figure 4
is a detail to be hereinafter referred to.
Figures 5, 6, 7, and 8 ilustrate different modifications in the construction of
certain parts of the telephone.
In the arrangement illustrated in Figures 1, 2, and 3 the telephone is constructed
with a magnet a oferi circular form, with its two extremities bent inwards so as
to converge towards the centre, thus bringing the two poles as near as possible to
the centre a circular vibrating plate b. In this plate is formed a semi circular
once c which, without in any way diminishing the efficiency of the apparatus,
communicates with a tube c', Figure 4; this tubes contains a vibrating tongue c² and
is attached to the underside of the vibrating plate b, as shewn in Figure 4, so that
by blowing into the mouth piece of the telephone a musical sound is produced, and
transmitted to the receiving apparatus for the purpose of attracting the attention
of the person in charge, as described in the Specification of the before mentioned
Letters Patent.
The magnet a is contained in a flat circular case d of wood having a cover d¹
with an orifice e in the centre provided with a tube e¹ of any convenient form and
length.
This cover which is attached to the sides of the case d, by means of screws d³,
carries the vibrating plate 6 hereinbefore referred to, the said plate being firmly
secured to the cover by means of a flat ring b¹ of copper and by screws b². A hole i
is provided in the bottom of the case for the escape of the air used in causing the
vibrations of the vibrating tongue c² in the tube c¹.
The magnet fits into the bottom of the case opposite to and parallel with the
vibrating plate, and is provided with poles f of soft iron attached to its extremities
by screws g and bent up at right angles, the vertical part of such poles forming the
magnetic cores of bobbins h which carry the wire and form the induction coils of
the telephone, these bobbins may be made of wood, copper, or any other suitable
material, and vary in their shape and dimensions according to the purposes to
which the telephone is to be applied.
The points of novelty characterizing the arrangement hereinbefore described as
well as the arrangements hereinafter described and the advantages derived there-
from are as follows:-
The employment of a semi-circular magnet of a form generally resembling that

page_text: also the poles are brought as near as possible to the centre of the vibrating
plate.
According to another part of this Invention, the advantages of the arrangements
herein before described are still further enhanced by means of certain alterations in
the arrangement and details of the construction.
In this arrangement the magnet is of the same form as that first hereinbefore
described, provided with prolongations or poles bent up at right angles forming the
cores of the induction coils of the telephone, but which are fitted into recesses
formed in the upper side of the extremities of the magnet to which they are attached
screws in lieu of being attached to the under side, as in the arrangement first
described.
One of the most obvious advantages of this telephone, constructed according to
this part or the Invention consists in the compact form of the apparatus, which is
obtained by constructig the case of the telephone of brass or any other suitable
alloy of metals, and reducing the height of the case without however interfering
with the efficiency of the pneumatic signal, which, as hereinafter described, admits
of being readily adapted to the special methods of construction hereinafter described.
The cover of the case is formed with a screw thread, so as to screw into the case
and form a tight joint.
The tube containing the vibrating tongue for producing the signal to call attention
may be arranged horizontally or parallel with the vibrating plate, to which it is
attached at one extremity by a short tube placed at right angles to the same, and
communicating with a hole formed in the said plate, as in the arrangement herein-
before described. In order to cause the tongue to vibrate the air blown in at the
mouth piece follows the course of the tube, and escapes from the case by the only
aperture with which it is provided.
Or the tube containing the vibrating tongue may, whilst being arranged hori
zontally, be attached to the side of the case covering the hole for the escape of air
in lieu of being attached to the vibrating plate without hereby impairing the
efficiency of the signal.
Or the two preceding arrangements may be combined in one apparatus, the two
tongues being caused to vibrate by air first passing through a tube attached to the
underside of the vibrating plate, and escaping through a tube attached to the side
of the case.

page_text: hereinbefore and hereinafter described has the effect of bringing the poles of the
magnet and the coils of the telephone as near as possible to the centre of the
vibrating plate or diaphragm, a position which has been found by experience to be
the most favorable to the proper action of the said plate. The employment of a
magnet of this form also has the advantage of avoiding the objectionable influence
of the two extremities upon one another which is always present when horse shoe
magnets with nearly parallel extremities are used. Moreover by employing magnets
formed according to this Invention it becomes possible to effect a considerable
reduction in the size of the case of the telephone, and to avoid almost entirely the
echo occurring in the large cases required for containing a magnet of the ordinary
horse shoe form.
It should also be observed that the shape of the magnets formed according to
this Invention has a tendency to concentrate towards the centre of the vibrating
plate, all the sounds produced in the case either by the employment of pneumatic
signals produced by the vibrating tongue hereinbefore referred to or by the vibra
tions produced in the telephone when employed as a receiver. This form of magnet
also has the advantage of admitting of the employment of a vibrating plate of
larger diameter than those ordinarily used, and thereby considerably augmenting
the power and efficiency of the apparatus. The effect obtained is also greatly
increased in consequence of the entire power of the poles of the magnet being
concentrated at a single point on the vibrating plate.
An important detail of construction consists in the arrangement of the orifice.e
in the centre of the cover, which orifice is provided with a short brass tube e¹, one
end of which is screwed into the said orifice, whilst the protruding portion, a part
of which is cut away as shewn at e², Figure 2, is connected to one extremity of a
flexible tube es of convenient length, so that when the telephone is placed upon a
table or other suitable support or suspended by a ring attached to the case, any
person desirous of making use of it can do so without the necessity of applying his
mouth directly to the orifice above the vibrating plate.
In order to prevent the flexible tube e³ from wearing out rapidly at the part
where it is attached to the telephone it is supported at one side by the brass, as
shown at in the Drawing, so as to obviate any undue strain at that part, and
the other end of the flexible tube is provided with a mouthpiece e in order to afford
facility for speaking and to direct the current of air blown into it by the person
using the apparatus in the most advantageous manner for the purpose of acting
upon the vibrating tongue or other musical instrument employed for producing the
signal to call attention and enabling it to emit the required sound.
According to the modification illustrated in Figure 5 the converging poles fof
the magnet are arranged in the same plane as the extremities of the magnet, which
in this example is placed at right angles to the vibrating plate, this form is more
particularly adapted for receiving battery currents and converting them into audible
sounds. According to this arrangement the extremities of the magnet a converge
towards the centre of a vibrating plate b, being prolonged by poles f, f, attached to
the said extremities by screws or otherwise. The wires forming the induction coils
of the telephone are coiled round these prolongations which form magnetic cores;
these coils may be formed on bobbins constructed as herein before described or in
any other suitable manner. By this arrangement also the poles are brought as
near as possible to the centre of the vibrating plate.
According to the modification illustrated in transverse section in Figure 6 the
advantages of the arrangements hereinbefore described are still further enhanced
by means of certain alterations in the arrangement and details of the construction
a is a magnet of the same form as that first hereinbefore described provided with
prolongations or poles which are bent up at right angles and form the cores of the
induction coils of the telephone, the said prolongations or poles being however in
this case fitted into recesses formed in the upper side of the extremities of the
magnet to which they are attached by screws in lieu of being attached to the
underside, as in the arrangement first hereinbefore described.
.

page_text: One of the most obvious advantages-of-telephones constructed according to this
modification consists in the compact form of the apparatus, which is obtained by
constructing the case_d and cover d' of the telephone of bronze or any other
suitable alloy or metal, and reducing-the height of the case without however
_ interfering with the efficiency of the pneumatic signal, which, as hereinafter
described, admits of being readily adapted-to-this-form-of-the-apparatus. The
cover d' of the case d is formed with a screw thread at its periphery so as to screw
into the case and form a tight joint.
c¹, Figure 6, is the tube containing the vibrating tongue c² for producing the
signal to call attention, and which in this case is arranged horizontally or parallel
with the vibrating plate b to which it is attached at one extremity by a short
tube c³ placed at right angles to the same and communicating with a hole c formed
in the said plate, as in the arrangement hereinbefore described. In order to cause
the tongue to vibrate the air blown through the orifice e follows the course indicated
by the arrows, and escapes from the case by the aperture i at one side of the case
for example.
Figures 7 and 8 are respectively a sectional and side elevation illustrating a
modification in the construction of the tube e¹ over the orifice e, the parts being
shewn in different positions in the respective Figures.
According to this modification the said tube is enabled to project at right angles
to the cover of the telephone in the position shewn in Figure 7, as in the arrange-
ment hereinbefore described, when it is required to speak into the apparatus, or to
blow into it for the purpose of producing the signal with the vibrating tongue, and
is also capable of being turned down out of the way of the orifice e into the
position shewn in Figure 8 when it is required to reproduce the sound of the
pneumatic signal received from another instrument with greater distinctness, or
when it is required to connect the orifice e with a trumpet to increase the sound, or
with any other form of mouth piece.
For this purpose a flanged ring or base k is firmly screwed into the orifice e in
the cover of the telephone, and the tube e¹ is connected to this ring / by means of
a hinge on one side and a spring catch m on the other side provided with a
button n, by pressing which latter one side of the tube e¹ is disconnected from the
ring, thereby enabling the said tube to turn on the hinge l.
It should be observed that the ring b¹ is represented as placed at a distance from
the plate b for the sake of clearness; but the two parts are to be assumed as having
been brought into contact by the aid of the screws b³.
Having now described and particularly ascertained the nature of the said Inven-
tion, and the manner in which the same is or may be used or carried into effect, I
would observe in conclusion that what I consider to be novel and original and
therefore claim as the Invention secured to me by the herein before in part recited
Letters Patent is,―
First. In telephones having a magnet and a vibrating plate normally out of contact
with the poles of such magnet, the employment of magnets of the peculiar con-
structions herein before referred to, with polar armatures carrying induction coils,
substantially as and for the purposes herein before described.
Second. The peculiar arrangement and combination of parts substantially as
herein before described, and illustrated in Figure 6 of the accompanying Drawings.
In witness whereof, I, the said John Henry Johnson, have to this my Specifi-
cation set my hand and seal, the Fifteenth day of July, One thousand eight
hundred and seventy nine.