IMPROVE- MENTS IN THE MEANS OF OPERATING MICROPHONES
Year: 1882

page_text: LETTERS PATENT to Philip Middleton Justice of Southampton Buildings
in the County of Middlesex Patent Agent for an Invention of IMPROVE-
MENTS IN THE MEANS OF OPERATING MICROPHONES Communicated to him
from abroad by François Van Rysselberghe of Schaerbeek in the Kingdom
of Bolaia
PROVISIONAL SPECIFICATION left by the said Philip Middleton Justice
at the Office of the Commissioners of Patents on the 19th July 1882.
PHILIP MIDDLETON JUSTICE of Southampton Buildings in the County of
Middlesex Patent Agent IMPROVEMENTS IN THE MEANS OF OPERATING
MICROPHONES A communication to me from abroad by François Van Rysselberghe
of Schaerbeek in the Kingdom of Belgium
When a microphone is used with an induction coil the induced currents arise
from variations in the intensity of the inducting current and these variations are
occasioned by the variations in the resistance which the imperfect contacts of the
microphone offer to the passage of the current Other things being equal,
variations of the resistance in the contacts have more relative value and the
variations of the current which result, are so much greater in proportion as the
total resistance of the circuit is weaker In fact if E be the electro motive power
of the microphonic battery R the resistance of that battery R, the mean resistance
of the microphone contacts and I the intensity of the microphonic current, you
have I:
and d I =
2d R, It is thus seen that d I is
maximum, for R₁ = 0 To produce therefore the inducting current an electro
motive force of extremely low interior resistance must be used Secondary
batteries otherwise called accumulators and thermo-electric piles have such qualiti-
cations and these apparata have not hitherto been employed for the special purpose
which I have indicated
=
E
R₁RS
E
(R: + R,+S)

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Philip Middleton Justice in the Great Seal Patent Office on the
18th January 1883.
PHILIP MIDDLETON JUSTICE of Southampton Buildings in the County of
Middlesex Patent Agent IMPROVEMENTS IN THE MEANS OF OPERATING
MICROPHONES A communication to me from abroad by François Van Rysselberglie
of Schaerbeek in the Kingdom of Belgium
When a microphone is used with an induction coil, the induced currents arise
from variations in the intensity of the inducting current and these variations arc
occasioned by the variations in the resistance which the imperfect contacts of the
microphone offer to the passage of the current. Other things being equal
variations of the resistance in the contacts have more relative value and the
variations of the current which result are so much greater in proportion as the
total resistance of the circuit is weaker In fact if E be the electro motive power
of the microphonic battery, R the resistance of that battery R² the mean resistance
of the microphone contacts and I the intensity of the microphonic current, you
have I =
and d I =
2d R. It is thus scen that dI is
maximum for R₁ = 0 To produce therefore the inducting current an electro
motive force of extremely low interior resistance must be used; Secondary
batteries, otherwise called accumulators and thermo electric piles have such qualifi-
cations, and as these apparata have not hitherto been employed for the special
purpose indicated, it is desired to secure the sole right of their application to
microphones
E
R₁ + R₂ + S
E
(R₁ + R + S)
Having thus described the invention as communicated to me by my foreign
correspondent What I claim and desire to secure by Letters Patent is
The means of increasing the intensity of the variations of an inductor current
arising out of the variations in the resistances of microphonic contacts and which
consists in employing for the microphone either a secondary battery or a thermo
electric pile
In Witness whereof I the said Philip Middleton Justice have hereunto set
my hand and seal this eighteenth day of January A.D. 1883
Signed, sealed and delivered
in the presence of
HENRY B HATCHWELL
53 Chancery Lane
London W.C
PHILIP M. JUSTICE (L.S.)