IMPROVEMENTS IN THE METHOD OF AND APPARATUS FOR TRANSMITTING MUSICAL TONES BY ELECTRICITY
Year: 1874

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincolns Inn Fields,
in the County of Middlesex, Gentleman, for the Invention of
"IMPROVEMENTS IN THE METHOD OF AND APPARATUS FOR TRANSMITTING
MUSICAL TONES BY ELECTRICITY.”—A communication from abroad by
· Elisha Gray, of Chicago, County of Cook, State of Illinois, United
States of America.
COMPLETE SPECIFICATION filed by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition
and Declaration, on the 29th July 1874, pursuant to the 9th
Section of the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Mid-
dlesex, Gentleman, send greeting.
WHEREAS I am in possession of an Invention for "IMPROVEMENTS-
IN THE METHOD OF AND APPARATUS FOR TRANSMITTING MUSICAL TONES BY

page_text: ELECTRICITY," and have petitioned Her Majesty to grant unto me, my
exccutors, administrators, and assigns, Her Royal Letters Patent for
the same, and have mado solemn Declaration that the said Invention
is communicated to me from abroad by Elisha Gray, of Chicago, County
of Cook, State of Illinois, United States of America.
NOW KNOW YE, that I, the said John Henry Johnson, do hereby
declare that the following Complete Specification, under my hand and
scal, fully describes and ascertains the nature of the said Invention and
in what manner the same is to be performed in and by the following
statement, reference being had to the accompanying Drawings and to
the letters and figures marked thereon, that is to say :—
This Invention relates to a method of producing musical tones of any
desired pitch at any point in an electrical circuit, and consists in trans-
mitting a series of impulses of induced electricity of high tension,
corresponding in number to the number of audible vibrations con-
stituting said musical tone, through living. tissue in contact with any
resonant substance, or through a coil surrounding a bar of iron or the
coro of an electro-magnet, the succession of currents being produced by
an induction coil or other apparatus for inducing a secondary current,
and being caused by the action of any suitable circuit interrupter
situated in a primary circuit.
And in order that the said Invention may be fully understood, I shall
now proceed more particularly to describe the same, and for that
purpose shall refer to the several Figures on the annoxed Sheet of
Drawings, the same letters of reference indicating corresponding parts
in all the Figures.
Figure 1 of the Drawings represents one form or plan of an electrical
apparatus in which these improvements are embraced; Figuro 2 is a
front elevation of the same, and Figure 3 is a diagram shewing an
mrangement of parts and circuits which may be employed in connection
with these improvements.
A represents the base or frame of the apparatus; B is an induction
coil of the usual form provided with the usual primary and secondary
helices; O is an ordinary vibrating electrotome which when in action
produces a musical tone, by the vibration of its armature and circuit
breaking spring a of a pitch determined by its rate of vibration, which
rate is dependent upon the length, stiffness, and adjustment of the spring

page_text: attached to the armature of the clectrotome; O' is another clectrotome
similar to the first with the exception that its spring a' is so adjusted
that it produccs when in action a musical tone of a different pitch from
that produced by the electrotome C, owing to the different rate of
vibration -of-its-circuit breaking spring a'. Other electrotomes³-may-bo
provided having their vibrating springs so constructed and adjusted that
wlien in action tho series will produce tones extending through one or
more octaves. These electrotomes are situated in the primary circuit of
the induction coil B, and when the said primary circuit is broken by the
vibration of the circuit breaking springs, secondary currents are induced
in the secondary circuit of the said coil.
D, D', are telegraphic keys of the usual form placed in the primary
circuit above referred to, which circuit is divided so that it passes through
both keys and both electrotomes. The keys are used for making con-
nection with the battery.
Figuro 3 shows the arrangement of, the circuits; G. being, tho
secondary circuit extending from the induction coil B to the receiving
station; F, the battery; and H, the primary circuit from the battery
through the koys; D, D', magnets of the electrotomes C, C¹, and tho
primary circuit of the induction coil B. E represents a suitable resonant
substance at the receiving station, and consists of a hollow cylinder of
metal.
.
"
The method of operation of the apparatus is as follows:-On depressing
çither of the keys D, D¹, the primary circuit from the battery F will be
closed through one of the electrotomes, and the spring or circuit
interrupter of the latter will immediately commence to vibrate, pro-
ducing a musical tone of a certain pitch dependent as before stated on
the size and adjustment of the spring, and interrupting the primary
circuit of the induction coil B. These interruptions will induce
secondary currents in the secondary circuit of the said coil, which will
correspond, in number with the vibrations of the circuit interrupter, and
the number of musical audible vibrations constituting the tone produced.
Thus for example if the circuit interrupting. spring vibrates one hundred
and twenty-eight times per second, the tone produced is that known as
the "fundamental O," and at the same time one hundred and twenty-
Leight terminal induced currents will be generated in the secondary
nirenit

page_text: The uses to which the apparatus may be applied are various. In
telegraphing for example, instead of transmitting messages by means of
the Morse alphabet now in general use, tones of different pitch corre-
sponding to the letters may be employed, which tones can be produced
more rapidly than printed or impressed dashes can be made, and their
duration would be shorter than the intermissions now required for
producing dashes and dots in succession.
A very slight interval would be necessary between the tones to
indicate the separation, and as dashes would be indicated by ono tone,
and dots by another, all signals would have the same length. Instead
of using one tone for dashes and another for dots, signals could be
devised consisting of tones of various combinations. These signals can
soon be readily learned and read by any operator capable of dis-
tinguishing tones of different pitch, who by placing his ear in contact
with the resonant substance, would cause the tones to be produced and
still have both hands free to receive the message. By means of a type
writer an operator could record about eighty words a minute.
The amount of current which is necessary to produce the effect is
almost unappreciable. Less than one hundredth part of the battery
power now required enables audible signals to be transmitted over long
lines. The apparatus can therefore be employed with advantage on sub-
marine lines, and the rate of transmission over them can be thereby
much increased.
As a telegraph apparatus it is simple, economical, and rapid in its
operation..
The apparatus may also be employed to transmit tunes from one place
to another, the vibrating pieces being properly pitched and sufficient in
number, even the different parts of a musical composition cach simul-
taneously played in different places may be transmitted to the samo
place, so that the whole will be there audible. In the latter case a
separate circuit and transmitting and receiving apparatus will be
required for cach part of the musical composition, and it will bo
necessary to beat time by telegraph for each set of performances.
The apparatus can also be employed with advantage in studying the
3 laws of acoustics.
Having now described and particularly ascertained the nature of the

page_text: carried into effect, I would observe in conclusion that what I consider to
bo novel and original, and therefore claim as the Invention is,-
First. The method of producing audible musical vibrations of any
desired pitch in a resonant substance, which is a conductor of electricity
by transmitting through living tissue in contact with said substance, a
series of electrical impulses of high tension corresponding in number with
said vibrations, substantially as and for the purpose herein-beforo described.
Second. The combination of an apparatus for producing a secondary
current of electricity, a series of vibrating electrotomes, or other circuit
breaking devices controlled by corresponding keys, and a resonant
receiver arranged in a secondary circuit, substantially as and for the pur-
pose herein-before described and illustrated by the accompanying
Drawings.
Third. The arrangement of a series of two or more vibrating automatic
electrotomes, whose vibrating circuit closers are so arranged as to produce
tones of different pitch in combination with keys for controlling the
same, substantially as herein-before described and illustrated by the
accompanying Drawings.
Fourth. The method of producing musical tones by causing the
vibration of a bar of iron surrounded by a coil of wire or the core of an
electro-magnet by transmitting a series of induced currents through the
coil surrounding said bar or coil, substantially as and for the purposo
herein-before described.
Fifth. The combination of an apparatus producing induced secondary
currents with a series of electrotomes or other circuit interrupters, and
an electro-magnet arranged in the secondary circuit, substantially as and
for the purposes herein-before described and illustrated by the accom-
panying Drawings.
In witness whereof, I, the said John Henry Johnson, have to this
my Complete Specification set my hand and scal, the Twenty- 3
ninth day of July One thousand eight hundred and seventy-
four.