Improvements in Microphonic Apparatus.
Year: 1889

page_text: Date of Application, 15th Aug., 1889
Complete Specification Left, 15th May, 1890-Accepted, 28th June, 1890
PROVISIONAL SPECIFICATION.
Improvements in Microphonic Apparatus.
ROBERT HENELADE COURTENAY of 6 Anerley Street Battersea Park Road in the
County of Surrey Telephonic Engineer do hereby declare the nature of this invention
to be as follows:-
This invention has for its object the construction of microphonic transmitters of
sound, the contact surfaces of which having less resistance in the primary circuit give
as a result loud sounds with perfect articulation and may be constructed as herein
under described.
I obtain excellent results from the transmitters constructed as follows
I make a compound of metalic substances in a fine state of division, such as silver,
platinum, or other suitable metals, and mix with a substance such as the flesh of dates
or figs with carbon powder capable of being formed into any shape preferably of
spherical form, by means of heat in a covered crucible the form is retained as a hard
carbonaceous substance. The spheres or other forms are coated with a good metalic
conducting surface by electro deposition or otherwise, leaving a small part of the
spheres or other forms bare, for contact surfaces. Or in lieu of the compound spheres
as above described, a hollow metal sphere may be used preferably of silver, copper,
brass, or any other metallic conductor. The spheres may be filled with particles of
carbon or a mixture of the compound described above, the spheres or other forms of
metal used in lieu of the composition are thoroughly coated with a surface of plumbago
or other suitable substance such as platinum black with or without plumbago, one or
more of these spheres or other forms are soldered or otherwise metallically connected
to brass or other metallic springs, the springs are affixed in a suitable case preferably
of wood with the spheres or other forms, one or more resting lightly against a disc or
other form of steel or iron wires connected to a strip of soft iron and enclosed in
membranes of parchment or other suitable thin substance, to which is soldered or
otherwise metallically connected a strip of metal of higher conductivity than that of
which the disc or armature is composed such as good copper, or silver, or an alloy of
good conducting metals the strip being sufficiently large to receive the contact parts
of the spheres or other form of conductors, the surfaces of the metal spheres or other
form of superior conducting metal connected to the iron strip are also coated with a
film of plumbago or other suitable substance as above described. The superior con-
ducting metal may be made in any form other than a flat surface and connected
metallically to the discs or armatures, such as a tube in trumpet like form, or a gong,
or other form capable of imparting sound by receiving the vibrations of the compound
or metallic spheres or other forms in electrical contact in which case the wood or other
case must be of suitable size and form.
COMPLETE SPECIFICATION.
Improvements in Microphonic Apparatus.
I, ROBERT HENELADE COURTENAY of 6 Anerley Street Battersea Park Road in
the County of Surrey, Telephonic Engineer do hereby declare the nature of this
invention and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement :-
-
This invention has for its object the construction of microphonic transmitters of
sound, the contact surfaces of which having less resistance in the primary circuit give
as a result loud sounds with perfect articulation and may be constructed as herein under
described.

page_text: I obtain excellent results from the transmitters constructed as follows:-
I make a compound of metallic substances in a fine state of division such as silver
platinum, or other suitable metals, and mix with a substance such as the flesh of dates
or figs so as to be capable of being formed into any shape desired preferably
sperical by means of heat in a covered crucible the form is retained as a bard
carbonacious substance. The spheres or other forms are coated with a good metallic
conducting surface by electro deposition or otherwise leaving a small part of the
spheres or other forms bare for contact surfaces. Or in lieu of the compound spheres
as above described a hollow metal sphere may be used preferably of silver, copper,
brass, or any other metallic conductor. The spheres may be filled with particles of
carbon or a mixture of the compound described above. The spheres or other forms
of metal used in lieu of the composition are thoroughly coated with a surface of
plumbago or other suitable substance such as platinum black with or without
plumbago. One or more of these spheres or other forms are soldered or otherwise
metallically connected to brass or other metallic springs and the invention will
be best further understood by describing same with reference to the accompanying
drawings.
Figure 1 is a vertical cross section of a sound transmitting apparatus, and Figure 2
is a front elevation with the diaphragm, and screw cap removed arranged according to
my invention.
Figure 3 is a back elevation of the diaphragm constructed according to my
invention.
Figure 4 is a front view of the diaphragm with the membrane removed.
Figure 5 is a vertical cross section through the line x y of Figure 4.
Figure 6 shews a back view of the receiving diaphragm composed of an armature
or disc without the conductors, used in the transmitter, the wires forming the disc,
when connected to the strip of soft iron form a compound magnet of the opposite pole
to the magnet through which the current is flowing in the receiving telephone and
may be used as a substitute for the ordinary iron disc in telephones.
Figure 7 shews the vibrating spring connected to the vibrating sphere through
the intervention of a tuning fork, such tuning fork being provided with a sphere as
above described connected to one of the prongs, which may be used as a substitute
for the springs and spheres as described and shewn with reference to Figures 1 and 2.
The springs A are affixed in a suitable case B with the spheres C or other forms one
or more resting lightly (and requiring when once adjusted no further adjustment)
against a disc or other form of steel or iron wires D connected to a strip of soft
iron E. In the drawing I have shewn a disc of copper E¹ fixed to the strip E and
it is against this disc that the sphere rests. All the parts except the surface of the
copper disc E' are enclosed in membranes of parchment or other thin substance
such as muslin or other fabric or material and waterproofed in any well known
way.
The strip of metal or disc as before described of higher conductivity than that of
which the armature is composed, may be of good copper or silver, or an alloy of
good conducting metals, the said strip being sufficiently large to receive the contact
parts of the spheres C or other form of conductors as aforesaid. The surfaces of the
metal spheres or other form of superior conducting metal and the iron strip are also
coated with a film of plumbago or other suitable substance.
The superior conducting metal may be made in any form other than a flat surface
and connected metallically to the armatures such as a tube in trumpet like form, or a
gong or other form capable of imparting sound by receiving the vibrations of the
compound or metallic spheres or other forms in electrical contact in which case the
wood or other case must be of suitable size and form.
The method of coupling up or connecting the apparatus for the purpose of trans-
mitting sound, is similar in all respects, as in the case of any well known microphone,
in circuit with battery, bell, switch, and line or line and earth.
For long distances the transmitter is connected in circuit with the primary of an
induction coil, with the secondary circuit connected to line, or line and earth in the

page_text: usual way,
with provision to call attention, either with magnets or ordinary electric
bells, as is well known and understood.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:
First. In microphonic apparatus, the steel or iron wires connected to a strip of
thin metal enclosed in membranes forming magnets and used for the double purpose
of transmitting and receiving sound substantially as described and illustrated with
reference to the accompanying drawings.
Second. In microphonic apparatus the use or employment of spheres composed of
carbonaceous composition or hollow metal spheres filled with the composition
described and connected to a spring, a part of which spring being if desired a tuning
fork vibrating against an armature of any description for the purpose of transmitting
sound substantially as set forth.
Third. The method of increasing the conductivity in the primary circuit of
transmitters of sound, by employing high conductors of electricity superficially
coated with conductors of high resistance substantially as herein before set forth.
Doted this 15th day of May 1800
R. H. COURTENAY.