AN IMPROVED METHOD OF AND MEANS FOR INCREASING THE EFFICIENCY " " OF TELEPHONES
Year: 1882

page_text: LETTERS PATENT to William Robert Lake of the firm of Haseltine, Lake,
3
& Co, Patent Agents Southampton Buildings London for an Invention of
AN IMPROVED METHOD OF AND MEANS FOR INCREASING THE EFFICIENCY
"
"
OF TELEPHONES communicated to him from abroad by Amos Emerson
Dolbear of Somerville, Massachusetts, United States of America.
PROVISIONAL SPECIFICATION left by the said William Robert Lake at
the Office of the Commissioners of Patents on the 8th December 1882.
"
WILLIAM ROBERT LAKE, of the firm of Haseltine, Lake, and Co., Patent
Agents, Southampton Buildings, London "AN IMPROVED METHOD OF, AND
MEANS FOR, INCREASING THE EFFICIENCY OF TELEPHONES [A communication to
him from abroad by Amos Emerson Dolbear of Somerville, Massachusetts, United
States of America.]
This Invention relates to telephonic apparatus and is chiefly designed to increase
the efficiency of the instrument invented by Professor Amos Emerson Dolbear
known as the electro static telephone and described in the Specification of former
Letters Patent dated March 29 A.D. 1881, No 1395
Since the date of the said former Letters Patent it has been discovered that when
one of the plates or terminals of the receiver is kept charged to a high potential
by a "Holtz" machine or other generator or source of electricity, the mutual action
and reaction between the two plates or discs of the said receiver, when the same is
used telephonically, will be much greater and the instrument will be much more
efficient than heretofore. It is manifestly not impossible to effect this result by the
use of a machine kept in continuous rotation, or by otherwise maintaining a
continuous supply of electricity; it is however obvious that a method of working
or using these instruments which involves the continuous rotation of a machine.
or the use of such a number of battery cells as is necessary to give the required
potential for so charging the instrument, would be highly inconvenient if not
impracticable; by my Invention I provide for charging the instrument, and keeping
it charged, without this inconvenience. It is well known to electricians that

page_text: shellac, gutta-percha, india-rubber, and other materials of like specific inductive
capacity are highly advantageous for use as dielectrics in condensers, and that these
substances possess the property of absorbing and retaining a static charge of
electricity. And I avail myself of this property in such a manner that the receiver,
when once charged, will remain in a highly efficient condition for many hours or
even days without being recharged.
For this purpose I construct the receiver with plates or discs of iron which are
varnished or coated with shellac or other material of sufficiently high specific
inductive capacity, and connect one or both of the same with the ends of the
secondary wire of an induction-coil as described in the aforesaid Specification, the
said plates being, as therein described, fitted in a case formed entirely, or partially,
of a good insulating material such as hard india-rubber, or the like, and I provide
for instantaneously or rapidly charging the plate or plates of the instrument by
the same induction-coil, or by another coil, by a machine, or otherwise. That is, I so
arrange the apparatus that the operation of charging the plates will not in any case
necessarily occupy more than a few moments. In some instances I charge the
instrument by means of the transmitter battery employed in connection with the
induction-coil, and I sometimes arrange the apparatus with provision for using
the bell battery for the charging, and part of the same battery for transmitting.
Or I may use for charging the receiver statically, before using the same tele-
phonically, any other means. or, devices which will be adequate and suitable for
instantaneously or rapidly communicating the charge to the instrument.

page_text: SPECIFICATION.in pursuance of the conditions of the Letters Patent filed by
the said William Robert Lake in the Great Seal Patent Office on the 8th June
1883.
"
WILLIAM ROBERT LAKE, of the firm of Haseltine, Lake & Co; Patent Agents,
Southampton Buildings, London, " AN IMPROVED METHOD OF AND MEANS FOR
INCREASING THE EFFICIENCY OF TELEPHONES A communication to me from
abroad by Amos Emerson Dolbear, of Somerville, Massachusetts, United States of
America
2
This invention relates to telephonic apparatus and is chiefly designed to increase
the efficiency of the instruments invented by the said Amos Emerson Dolbear and
described in the Specification of former Letters Patent Dated March 29th A,D, 1881,
N° 1395, which instruments are commonly known as electrostatic receivers.
It has been discovered that when one or both plates of the said receiver are
kept charged to a high potential, by a Holtz machine or other generator, the
working of the said receiver is materially improved and while it is possible to
effect this result by the continuous rotation of a machine for generating electro-
motive force, or by the employment of a great number of battery cells, yet neither
of these methods is well suited for general use; and the object of the present
invention is to provide for charging the plate or plates of the said receivers and
keeping them charged, without the inconvenience arising from the use of the means
above mentioned.
It is well known that when a conductor is charged, whether the conductor form
part of a closed circuit or not, a dielectric such as shellac or other material of like
specific inductive capacity in contact with it possesses the property of absorbing
and retaining a charge, and I avail myself of this property by making the receiver-
plates of metal, coated with shellac or other dielectric of like specific inductive
capacity and charging the dielectric by a charge of high potential in the metal,
preferably by rapidly making and breaking the primary or battery circuit of an
inductorium to the secondary of which the plate to be charged is connected, as
hereinafter more fully described.
In the accompanying drawing.
Figure 1 shews, in transverse section, a portion of one of the plates drawn to an
enlarged scale; a represents the metallic plate and a' the coating of shellac or
similar dielectric.
Figures 2 and 3 are diagrams illustrating the practice of the said invention.
Before the date of the present invention it was thought necessary to connect the
metal plate with some generator of continuous high electro-motive force, such as a
battery of many cells, or a Holtz machine kept in rotation. This not only kept the
metal plate charged but also necessarily charged the line with which the said metal
plate was in electric connection, and, while efficient as to the desired result, was
objectionable for other reasons.
In Figure 2 the plate is connected with a line of which the secondary coil of
the inductorium I forms a part; in the primary circuit p of this inductorium there
is a circuit-breaker or interrupter P by the operation of which the circuit can be
rapidly made and broken, thereby inducing momentary electro-motive force in the
secondary coil of the inductorium I and the line l, and alternately charging and
discharging the metal plate a so that the coating a' soon becomes charged and it
will remain in this condition for a considerable time, in some cases for several
days.
In the practical use of this apparatus, the person about to use the telephone first

page_text: operates the circuit-breaker P for a few seconds, then talks to the transmitter T in
the usual manner, and is heard at the receiver T¹.
In Figure 2, the line is an open circuit and the plates form the terminals of such
circuit; but this arrangement is not essential, for the line may be a closed circuit,
provided a resistance be interposed, say as shown at R in Figure 3, to cause
sufficient electric pressure or potential at that point in the line at which the plate
of the receiver T₁ is connected. The other plate of the receiver T¹ in Figure 3 may
be grounded or otherwise arranged as described in the above named specification.
The construction of the receiver T' is substantially the same as described in the
said specification except that the plates are coated with shellac or other dielectric
as above specified; in practice the well known ferrotype iron is used in making
these plates.
.
Having thus fully described the said invention as communicated to me by my
foreign correspondent, and the manner of performing the same, I wish it under-
stood that I do not claim the charging of the receiver plates by means of a Holtz
or other machine kept in continuous rotation, or by a battery in the line, nor do
I limit myself to the precise means specified for charging the receiver plates, as I
may employ other known means for rapidly varying the current in the primary of
an inductorium, whose secondary constitutes the line in combination with a receiver
whose plates are coated with shellac or the like;-But I claim.
In combination with the receiver plate or plates composed of metal coated with
a dielectric, an inductorium whose primary contains a circuit-breaker, adapted,
when in operation, to induce a high electro-motive force in the secondary circuit
and thereby charge the dielectric for the purpose specified.
In witness whereof I the said William Robert Lake have 'hereunto set my hand
and seal this eighth day of June in the year of our Lord One thousand
eight hundred and eighty three.