IMPROVEMENTS IN TELE- PHONES
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by George Henry Bassano, Albert
Edward Slater and Frederick Thomas Hollins at the Office of the Commis-
sioners of Patents on the 3rd February 1883.
GEORGE HENRY BASSANO, ALBERT EDWARD SLATER and FREDERICK THOMAS
HOLLINS, all of Derby in the county of Derby.
"IMPROVEMENTS IN TELE-
PHONES
">
Telephones at present are mainly formed on the principle of a plate capable of
inductive action vibrating before or between the poles of an electric or permanent
magnet..
Our invention is designed to produce telephones in a simple and cheaper manner
than heretofore and capable of giving good results. Our invention consists,
firstly
In making the vibrating plate, the pole piece of an electro magnet, thus
polarizing the plate itself, and causing magnetic tension in the plate thus
magnetised by placing before it a piece or pieces of suitable iron or steel, magnetic
or non-magnetic.
One way of doing this is to arrange a series of iron rods or wires or permanent
magnets of any suitable shape usually forming a hollow cage and to the one end of
all these secure a plate or diaphragm. Round the hollow cage or core we wind
insulated wire of desired guage and conductivity, We make an adjustable iron
bar or use a permanent magnet to produce the tension on the diaphragm as before
described. We do not bind ourselves to this exact form as the details may be
varied without departing from the principle thereof.
When the tension of the magnetic field is varied by a variable current being
sent round the electro magnet, the plate must vibrate in front of the iron rod or
magnet, thus reproducing sound as usual.
Secondly. In another form of receiver we so arrange an electro magnet that a
portion of it can be capable of receiving sonorous vibrations, and before one or
both of its poles.
One way of effecting this is to form a portion of the magnet core flattened out
and then bored out in this flattened portion to form a part capable of vibration,
other portions carrying the coil, or coils being bent round or arranged to come
near the thin portion or on both sides of it.
Thirdly. We frequently prefer to use a non-inductive metal diaphragm and to

page_text: render the same capable of attraction and repulsion in a magnetic field, we fix in or
to it a suitable piece or pieces of iron or steel magnetized or not as required.
Fourthly. We construct another form of telephonic receiver by connecting
rigidly or loosely to a vibrating diaphragm an armature or elongation or extension
of an armature of an electro magnet, and causing the same to be attracted or
repelled by the pole piece of an adjacent electro magnet, or iron or steel bar
magnetized or not.
One method is to draw out or attach to the end of the magnet core a knife-edge
or point capable of rocking on a suitable surface, the other end of the magnet
carrying an adjustable rod from the diaphragm. Another method is to carry a
knife-edged or pointed rod from the diaphragm rocking in a solenoid.
Another method is to use a light thin plate or armature fastened at both ends
and attached to the diaphragm by a pin or otherwise, and vibrating before the
electro magnet.
Fifthly. Another form of receiver consists in placing iron or steel rods or magnets
with their ends thinned so as to be capable of vibration, radially or otherwise
round a diaphragm and with their other ends attached to the plate or to a pad or
stud fixed thereto. An electro magnet is placed before the diaphragm so as to
impart magnetic tension by causing such vibrating magnets to be pressed against
the plate with a force varying with the intensity of the current sent round the
coils of the electro magnet.
Sixthly. Another form of receiver consists of an armature vibrating before
the poles of a permanent magnet and with one end thinned into a spring pressing
on a diaphragm. To give magnetic tension to the armature we place another
magnet on the other side by which it is pulled on to the diaphragm