IMPROVEMENTS IN APPARATUS FOR TRANSMITTING SOUNDS BY MEANS OF ELECTRICITY
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by Edward James Paterson at the Office
of the Commissioners of Patents on the 29th June 1881..
EDWARD JAMES PATERSON, of Finsbury Park Road, in the County of Middlesex.
"IMPROVEMENTS IN APPARATUS FOR TRANSMITTING SOUNDS BY MEANS OF
ELECTRICITY."
This Invention relates to a means for simplifying and improving instruments
used for transmitting speech or articulate sounds, and known as "carbon trans-
mitters." The transmitters, in which more than one carbon contact is used, have
hitherto been for the most part made by attaching blocks of carbon to an elastic
diaphragm, with connecting bars or rockers of carbon resting freely on and between
these blocks, which bars are sensitive to the vibrations conveyed by the diaphragm.
In these the diaphragm is a recipient of the sound waves.
According to my Invention I dispense with the diaphragm and use several carbon
blocks, of which one or more are fixed firmly to a base and electrically connected
to one pole of a battery, while I support the remainder elastically from a fixed base,
connecting them with the other pole of the battery. Or in some cases I support
all the blocks elastically from a fixed base.
These various blocks I connect with one another by means of carbon rockers,
and the sound waves to be transmitted will impinge directly on the carbons
without the intervention of a diaphragm. Thus without disturbing their arrange-
ment, inter se, the moving carbons will be vibrated, and acting on a current passing
through the instrument will produce the so called undulatory state necessary to
the reproduction of similar and equal vibrations in a diaphragm at the receiving end
with the assistance of electro magnetic action.
Another point in my Invention is that I employ carbon rockers of different
sizes with the following object :-Most carbon transmitters of this class are
constructed with the diaphragm placed sloping; by this means there is a variation
of incidence of the carbon rockers on their bearings, some pressing with more dead
weight than others. The object of this is, that as the acoustic waves produced by
articulate speech are complex, some being of less and some of greater amplitude, it
is necessary to have the various channels through which the current passes
proportioned to these various factors, and this is the case when some press heavily
and some lightly on their bearings, the lighter rocking easily and others less
easily.

page_text: According to my Invention I obtain this variation by using carbon rockers of
different gauges and therefore of different weights, and by this means I avoid the
necessity for setting them on the incline, but can use them in either a horizontal or
an upright position. This allows of economy and convenience in manufacture, and
affords facilities in practical use. I would remark that various dispositions of the
carbon blocks may be adopted; thus, for example, a simple and efficient arrange-
ment is that in which one block is mounted elastically on end tension wires between
two parallel fixed blocks, and the three blocks are connected together by two sets
of four rockers of varying gauge or diameter. Again, the middle block may be the
centre of a group of fixed blocks, and connected with them by rockers arranged
radially around the elastically supported block, which block may either be carried
by tension wires, or supported by a central wire.
From these examples it will be seen that the instrument is susceptible of various
modifications in its arrangement, the principle of construction being nevertheless
strictly maintained.