IMPROVEMENTS IN TELEPHONE CALL OR SIGNALLING APPARATUS
Year: 1882

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for an Invention of "IMPROVEMENTS IN
TELEPHONE CALL OR SIGNALLING APPARATUS." A communication from
abroad by George Milton Hopkins, of Brooklyn, in the County of Kings and
State of New York, United States of America.
PROVISIONAL SPECIFICATION left by tho said Alexander Melville Clark
at the Office of the Commissioners of Patents on the 11th February 1882.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of
Middlesex, Patent Agent. "IMPROVEMENTS IN TELEPHONE CALL OR SIGNALLING
APPARATUS." [A communication from abroad by George Milton Hopkins, of
Brooklyn, in the County of Kings and State of New York, United States of
America.]
The object of this Invention is to provide a simple and effective call for telephone
lines. The Invention relates to the class of signalling apparatus employing
magneto or induction currents in connection with polarized bell magnets.
A. Siemens magneto electric machine is used and the wire of the armature is
connected at one end with its shaft which is in metallic contact with its supporting
fram attached to the poles of the U shaped permanent magnet which is in turn
connected by a wire to a binding post to which the ground wire is attached. The
other end of the armature wire is connected electrically with its pivot which is
insulated from the body of the armature and is pressed by a spring which is
insulated from the permanent magnet and connected with the upper contact with
a spring key.
This spring key is connected with the binding post to which the line wire is
attached. The lower contact of this key is connected with one end of the coils of
an electro magnet whose other end is connected with the binding post to which the
ground wire is attached. The yolk of this electro magnet to which its cores are
fixed is shaped and is secured to the face of one limb of the permanent magnet.
To the other limb is attached an iron support in which is pivoted the armature of
the electro magnet opposite to but not touching its poles.

page_text: This armature swings easily and carries a bell hammer which strikes the inner
surface of the bell at opposite points. The hammer head is provided with a screw
cap at either end for adjusting its length. By this construction the electro magnet
and its armature are polarized and the magnet being wound with fine wire is
readily affected by a current from a magneto electric machine like that above
described. This machine as will be noticed is not provided with a commutator so
that the current sent from it is alternating in its character.
The instrument is connected with another like it by the line wire. When an
alternating current is generated by turning the armature of the magneto electric
machine by means of the crank handle and friction gear provided for the purpose
the spring key is pushed against its upper contact by pressing on a button. The
alternating current passing over the line to the distant station rapidly. changes
the polarity of the bell electro magnet causing its armature to vibrate and ring
the bell. In a modified form of magneto call, the electro magnet is of the usual
construction excepting that each arm of the magnet is wound with two sizes of
wire. The portion of its length between the middle and the yoke is wound with
ordinary coarse magnet wire, about No. 18 in the same way as an ordinary electro
magnet and its terminals are connected with a current reversing key of ordinary
construction connected with a local battery. The extremities of the limbs of the
magnet are wound with very fine wire, say No. 36, in the same way as an electro
magnet and the terminals of the fine wire are connected one to earth the other
to line.
A yoke of non-magnetic material is placed on the poles of the electro magnet
permitting the poles to project slightly through it. To this yoke is secured an
iron support for the pivots of the armature which carries a bell hammer capable
of striking diametrically opposite sides of the bell. Upon opposite sides of the
electro magnet are placed two permanent bar magnets with like poles in the same
direction. These magnets touch and are fastened to the iron yoke of the electro
magnet and their opposite ends are clamped against the support of the armature.
The armature and magnet are by this means polarized.
By sending positive and negative currents through the coarse wire of the electro
magnet positive and negative currents are induced in the fine wire of the magnet
and the wire being in electrical communication with the fine wire of a similar
electro magnet in a distant instrument. The alternating induced current acting
upon the magnet cores causes the armature to be alternately attracted and repelled
producing a vibratory motion in the bell hammer and ringing the bell. By means
of this device signalling can be effected over much longer distances than is possible
with ordinary battery currents.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Melville Clark in the Great Seal Patent Office on the
11th August 1882.
ALEXANDER MELVILLE CLARK of 53 Chancery Lane, in the County of
Middlesex, Patent Agent. "IMPROVEMENTS IN TELEPHONE CALL OR SIGNALLING
APPARATUS." A communication from abroad by George Milton Hopkins of
Brooklyn, in the County of Kings and State of New York United States of
America.
The object of this Invention is to provide a simple and effective call for telephone
lines. The Invention relates to the class of signalling apparatus employing
magneto or induction currents in connection with polarized bell magnets. Figure 1
of the Drawings is a front elevation of one form of the improved signalling
apparatus. Figure 2 is a vertical transverse section of the same taken on line xx
in Figure 1. Figure 3 is a front elevation of a modified form of signalling
apparatus, and Figure 4 is a vertical transverse section taken on line y, y, in
Figure 3.
In Figure 1. A is the magnet and B, the rotating armature of the well known
Siemens magneto electric machine. The armature shaft is provided with a small
friction wheel C, which receives motion from the larger friction wheel D, the latter
being provided with a crank for turning it by hand. The wire of the armature B
is wound longitudinally in the groove of the armature and one of its terminals is
connected with the metal shaft of the armature which being in metallic contact
with the frame E, at the end of the magnet, communicates the current to the frame
whence it is conducted by the wire a to the binding post b, the latter being
connected with the ground wire c.
The other terminal of the armature wire is connected electrically with the
pivot d, which is insulated from the body of the armature and is pressed by spring e
which is insulated electrically from the magnet A, and is connected with the upper
contact, of the spring key F. The key F is connected by a wire with the
binding post G which receives the line wire H. The lower contact g of the key F,
is connected by a wire h with one terminal of the bell electro magnet I, the other
terminal of which is connected with the binding post b. The yoke of the magnet I,
is shaped and is secured to the face of one of the arms of the permanent U
magnet A. To the other arm of the magnet A is attached the iron support i for
the pivotted armature k. This armature is located near but not touching the poles
of the magnet I, and swings easily on the pivotal screws 1, 2, in the support i. The
armature carries a bell hammer m which is arranged to strike the inner surface of
the bell n, at diametrically opposite points. The hammer head is provided with a
screw cap o, at either end for adjusting its length. By this construction the
magnet I, and its armature k are polarized and the magnet being wound with fine
wire is readily affected by a current from a magneto electric machine like that
above described. This machine as will be noticed is not provided with a com-
mutator so that the current sent from it is alternating in its character.
The instrument is connected with another like it by the line wire H. When an
alternating current is generated by turning the armature B, the key F is to be
pushed against its top contact f, by pressing on the button a². The alternating
current passing over the line to the distant station rapidly changes the polarity of
the bell inagnet I at the distant station causing its armature to vibrate and ring
the bell.
In the modified form of magneto call shown in Figures 3 and 4 the electro

page_text: magnet A', is of the usual construction, excepting that each arm of the magnet is
wound with two sizes of wire. The portion of its length between the middle a¹
and the yoke b¹, is wound with ordinary coarse maguet wire about No. 18 in the
same way as an ordinary electro magnet, and its terminals are connected with the
current reversing key B', of ordinary construction connected with a local battery.
The extremities of the arms of the magnet are wound with very fine wire say
No. 36 in the same way as an electro magnet and the terminals of the fine wire
are connected one with ground C³, the other with the line D¹.
A yoke E of non magnetic material is placed on the poles of the magnet A¹
permitting the poles to project a short distance through it. To this yoke E¹, is
secured an iron support c¹, for the pivots of the armature F¹, which is supported a
small distance from the poles of the magnet A'.
The armature F' carries a bell hammer d', which is capable of striking
diametrically opposite sides of the bell G¹. Upon opposite sides of the magnet A¹
are placed two permanent bar magnets H, with like poles in the same direction.
These magnets touch, and are fastened, to the iron yoke b' and their opposite ends
are clamped against the support c' of the armaturo F'. The armature and magnet
are by this means polarized.
By sending positive and negative currents through the coarse wire of the
magnet A¹ positive and negative currents are induced in the fine wire of the
magnet and the wire being in electrical communication with the fine wire of a
similar magnet in a distant instrument, the alternating induced current acting
upon the magnet cores causes the armature F¹ to be alternately attracted and
repelled by the poles of the magnet producing a vibratory motion in the bell
hammer and ringing the bell. By means of this device signalling can be effected
over much longer distances than is possible with ordinary battery currents.
Having described the nature of the said Invention and the manner of performing
the same I declare that what I claim as the Invention to be protected by the
hereinbefore in part recited Letters Patent is :-
1st. In a signalling apparatus for telephone lines, the combination of the bell
electro magnet I, and armature k with the permanent magnet A of a magneto-
electric machine substantially as herein described.
2nd. In an electro-magnetic call-bell, the hammer m, having adjustable ends o,
as herein specified.
3rd. In signalling apparatus for telephone lines, the electro magnet A' wound
with coarse and fine wire as herein specified and provided with polarizing per-
manent magnets H, in combination with the local and line circuits as herein
specified.
4th. The magnet A¹ wound with coarse and fine wire and provided with
polarizing magnets H, in combination with the pivoted_bell armature F¹, as herein
specified.
5th. The electro-magnet A¹ wound with coarse and fine wire and provided with
a polarized armature F¹, in combination with a local batttery, and current reversing
key substantially as herein specified.
In witness whereof I the said Alexander Melville Clark have hereunto set
my hand and seal this Tenth day of August in the year of our Lord One
thousand eight hundred and eighty two.