IMPROVEMENTS IN TELEPHONE TRANSMITTERS
Year: 1882

page_text: LETTERS PATENT to Richard Theiler and Meinrad Theiler both of 86
Canonbury Road Islington, in the County of Middlesex for an Invention
of IMPROVEMENTS IN TELEPHONE TRANSMITTERS
(Void by reason of the Patentee having neglected to file a Specification in
pursuance of the conditions of the Letters Patent.)
PROVISIONAL SPECIFICATION left by the said Richard Theiler and
Meinrad Theiler at the Office of the Commissioners of Patents on the
8th February 1882.
RICHARD THEILER and MEINRAD THEILER both of 86 Canonbury Road,
Islington, in the County of Middlesex IMPROVEMENTS IN TELEPHONE
TRANSMITTERS
This Invention relates to the construction of apparatus for the electric trans-
mission of articulate speech and has for its object the obviation of certain faults
and disadvantages which exist in the various forms of telephone transmitters
hitherto in use. In most of the apparatus hitherto constructed for the same
purposes the sound vibrations were first caught up by a tympanum or sounding
board, usually terined diaphragm, and this then either communicated the received
vibrations to a series of contacts called "microphone," or it exerted a varying
pressure upon a fixed, but elastic, conductor. All such diaphragms, whatever
material they are made of, give out a sound or musical tone of their own when
vibrating freely and this sound interferes with the clear and accurate transmission
and reproduction of articulate speech. Any variation of temperature also alters
the tension of such diaphragms and consequently disturbs the requisite a ljustinent
when a fixed contact is used. Such diaphragms are moreover incapable of trans-
nitting and reproducing certain parts of articulate speech, as for example the
sound of the letter S. All these faults and disadvantages are obviated by our
Invention. We do not make use of any diaphragm whatever, but cause tho
vibrations to impinge upon any mass or substance which is capable of transmitting
ID 2.73

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such vibrations in a longitudinal direction. In one form or construction of our
apparatus we use cane, pith or straight grained pine wood and fix either of these
substances in such a manner that the vibrations impinge upon the end or cross cut
thereof. The size and shape of the said substances is immaterial. We then fix &
series of contacts, usually called "microphone on the opposite end or cross cut of
the said substance and connect the microphone in the usual manner with a battery
circuit. The form of microphone we prefer to use consists of 2 fixed carbon or
metal cylinders with a third cylinder suspended in such a manner that it slightly
leans against the fixed cylinders and thereby completes the circuit. In another
form or construction of our apparatus we suspend a short bar or a block of any
substance capable of transmitting sound vibrations and cause such bar or block to
lean slightly against one or more fixed contacts or conductors whereby the battery
battery which may include an induction coil is completed. The sound vibrations
impinge directly upon this suspended bar or block, Several bars or blocks may be
used. When the suspended substance is a non conductor of electricity we attach a
conductor to that part of it which leans against the fixed contact or contacts. By
making the suspended bar or block of a shape possessing sharp edges the trans-
mission of the sound of the letter S is easily accomplished. In the form of
apparatus last described the contacts or conductors need not consist of carbon.
We obtain the same results by making those contacts of tellurium and its alloys or
of an alloy of antimony and tin.
Sometimes we cause the aforesaid bar or block to lie on the fixed contact or
contacts in a horizontal position instead of suspending it vertically.