IMPROVEMENTS IN ELECTRIC TELEGRAPH APPARATUS
Year: 1873

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane,
in the County of Middlesex, Patent Agent, for the Invention of
"IMPROVEMENTS IN ELECTRIC TELEGRAPH APPARATUS." -A communication
from abroad by William Edward Sawyer, of Washington, District
of Columbia, and James Gilmore Smith, of the City, County, and
PROVISIONAL SPECIFICATION left by the said Alexander Melville
Clark at the Office of the Commissioners of Patents, with his
Petition, on the 13th October 1873.
I, ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN ELECTRIC TELEGRAPH Apparatus,”
to be as follows:-
This Invention is specially adapted for use in that system of tele-
graphing (by ocean cable) in which the electric current is sent through
a helix containing a delicately suspended mirror, which being deflected

page_text: to the right or the left, according as the current is positive or negative,
throws a ray of light to the right or the left correspondingly.
The chief object of this Invention is to increase the speed of trans-
mission which in the system now in use is slow and imperfect. This I
accomplish principally by the combination of a keyboard with cylinders
or wheels, or divisions of a cylinder or wheel in the transmitting
apparatus, and of cylinders or wheels or divisions of a cylinder or wheel
in the receiving apparatus in conjunction with suitable auxiliary
mechanism. Each of said cylinders or wheels is adapted to revolve, and
has teeth fixed in its periphery which engage with contact levers
pivoted to the several keys in the transmitting apparatus, when the keys
are pressed, and with the keys in the receiving instrument when they
are pressed.
The transmitting apparatus consists of two cylinders, or one cylinder
divided into two parts, each cylinder or division of the one cylinder
being studded with thirteen (or more) teeth placed at regular intervals
spirally. Each of the thirteen teeth on each cylinder or division of the
cylinder represents a letter of the alphabet, the thirteen keys manipulated
to come in contact with the teeth on one cylinder or division of the
cylinder being used to transmit the positive current, and the remaining
thirteen keys manipulated to come in contact with the teeth on the
other division of the cylinder being used to transmit the negative
current.
The receiving apparatus consists of two wheels or cylinders, or two
divisions of a wheel or cylinder revolving synchronously with the
cylinders or divisions of the cylinder of the transmitting instrument.
Each wheel or cylinder, or division of a wheel or cylinder, is armed with
thirteen (or more) projecting teeth arranged preferably on the periphery
and corresponding in significance to the teeth on the cylinders or
divisions of the cylinder of the transmitting instrument.
In proximity to these revolving wheels or cylinders are two pivoted
levers which have preferably the form of ordinary telegraph keys, and
which upon being pressed come in contact with the teeth of the afore-
said wheels or cylinders.
The contact of a wheel with a tooth on a wheel or cylinder closes
a local circuit, and thereby causes an electro-magnet in a type writing
or printing machine to release a letter corresponding to the letter

page_text: represented by the tooth aforesaid, which letter is printed in the usual
way, a local electro-magnet being required for each letter of the type
printing machine represented by the teeth on the wheels or cylinders, or
divisions of wheel or cylinder.
In order that the lever making the local connection may be separated
from contact with the tooth, the instant the circuit is closed an electro-
magnet is arranged to act thereon simultaneously with the action of the
electro-magnet of the type writing or printing machine on the type.
One key is manipulated by the left hand of the operator on the wheel
or cylinder representing one division of the alphabet or 13 letters (or
more), and the other by the right hand of the operator on the second
wheel or cylinder representing the other 13 letters (or more), the one
key being operated when the positive current is used, and the other
when the negative current is used by the transmitting operator.
In order that the operator at the receiving instrument may utilize both
hands in manipulating the keys, and in order to secure more space
between the points representing the letters of the alphabet on the
periphery of the cylinders or wheels, the alphabet is divided into two
parts having reference to the frequency of occurrence of letters in words,
the same division being necessarily made in the transmitting apparatus.
The mirror in the helix (as now used in ocean telegraphy) being
deflected in one direction or another, according as the electric current
transmitted by the contact of a key with a tooth on the cylinder or
division of the cylinder in the transmitting apparatus is positive or
negative, the operator at the receiving instrument presses the key at the
right hand or left hand when the key comes in contact with a tooth on
the right or left hand cylinder or wheel, or division thereof, and a
current from a local battery is thereby sent through the electro-magnet
of the type writing machine before referred to, corresponding to the
tooth on the cylinder or wheel of the receiving apparatus in contact
with the key.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Alexander Melville Clark in the Great Seal Patent
Office on the 9th April 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirteenth day of October, in the year of
our Lord One thousand eight hundred and seventy-three, in the thirty-
seventh year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Alexander Melville Clark, Her special
licence that I, the said Alexander Melville Clark, my executors, admi-
nistrators, and assigns, or such others. as I, the said Alexander
Melville Clark, my executors, administrators, and assigns, should at any
time agree with, and no others, from time to time and at all times
thereafter during the term therein expressed, should and lawfully might,
make, use, exercise, and vend, within the United Kingdom of Great
Britain and Ireland, the Channel Islands, and Isle of Man, an Invention
for "IMPROVEMENTS IN ELECTRIC TELEGRAPH APPARATUS," a communication
to me from abroad by William Edward Sawyer, of Washington,
District of Columbia, and James Gilmore Smith, of the City, County,
and State of New York, both in the United States of America, upon the
condition (amongst others) that I, the said Alexander Melville Clark,
my executors or administrators, by an instrument in writing under my,
or their, or one of their hands and seals, should particularly describe
and ascertain the nature of the said Invention, and in what manner
the same was to be performed, and cause the same to be filed in the
Great Seal Patent Office within six calendar months next and immc-
diately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Alexander Melville Clark, do
hereby declare the nature of the said Invention, and in what manner
the same is to be performed, to be particularly described and ascertained
in and by the following statement, reference being had to the accom-
panying three Sheets of Drawings and to the letters and figures marked
thereon (that is to say): -
This Invention relates to a new and improved method and apparatus

page_text: for increasing the rapidity of cable telegraphy by the aid of a local
circuit, a transmitting key or keys, and recording apparatus for the
attendant who takes the signals of the galvanometer to record them.
The plan herein adopted comprises a transmitting cylinder whereon.
teeth are arranged to represent the letters of the alphabet with a
transmitting key for cach letter, half the keys or thereabout being
arranged to transmit positive and the other half negative currents, and
the teeth for each set of keys being arranged for giving long and short
impulses in about equal proportions, so that the beams of light produced
on the galvanometer will be of four different kinds, viz., short and long
on one deflection, say the right, and the same on the left, to facilitate the
reading and recording of them, and thereby increase the rapidity of
transmission.
In front of the galvanometer on the receiving side of the ocean or at
the receiving office is an operator's table, whereon there are four circuit
telegraph keys for two operators, one of whom notes the positive signals
and transmits the long signals by one key, and the short ones by the
other to a receiving cylinder, and the other operator does the same for
the negative signals. This receiving cylinder has slips on it for the
alphabet, arranged in the same order as the teeth on the transmitting
cylinder in respect of the circumferential position, and both cylinders
are caused to revolve synchronously by clockwork or other means if
preferred.
The receiving cylinder is in a circuit with a printer having a printing
hammer or lever for cach letter, so that the current transmitted to it
from the operator's table at the galvanometer is certain to go to the
same letter or its representative slip on the receiving cylinder that was
transmitted from the sending cylinder, and through it to the printer,
although the operators at the galvanometer have no knowledge of the
letters which the signals they send represent. Thus the apparatus is
mechanically accurate and the liability of errors on the part of the
operators by the present mode of reading the combinations of signals of
the galvanometer forming letters is avoided. Moreover in this system
each signal represents a letter and the time lost in the old system in
giving two or more signals for a letter is saved, and again as the
operators have only to note a single point of difference in the signals,
and as the signals are divided between two operators the rate of

page_text: transmission can be greatly increased. But this Invention is also
applicable to this or any code of signals, and I do not limit myself to
any particular code nor to any particular kind of printing or recording
instruments.
Figure 5 represents a couple of the transmitting keys in plan.

page_text: those marked with a dash are the keys for positive currents and the
others are the negatives, the former are included in a local circuit,
say F, and the others in another G, both of which include the cable H
also.
A closed circuit is maintained through these keys by a movable
piece I on one connected by a wire J with a stationary piece K on the
next lever in the same circuit, and so on throughout the series, as shown
in Figure 5, said pieces being insulated on the levers.
The circuit is closed when the two pieces I and K of each lever touch,
and each piece I has a spring L to keep them together. When a key is
pressed down its piece I is thrown up into the path of its tooth on the
cylinder so that it is caught by the tooth and pulled away from contact
with its fellow K, which breaks the local circuit, and thus turns the
current into the cable and causes an impulse to be sent through it to
the galvanometer M at the other end of the cable (see Figure 1); as
soon as the tooth escapes from the piece I, the. spring L throws it back
against K and closes the local circuit through which the current will
again proceed without electrifying the cable in consequence of the
greater resistance of the cable.
The connections of the keys above described being hidden by the
cylinder A in Figure 3, they are merely indicated by the lines F¹, G¹, and
and the springs L, which show the connections to be in accordance with
the positive and negative keys. N represents the operator's table in front
of the galwanometer, where the beams cast upon the screen by it when
deflected by the currents transmitted from the other end of the cable
can be readily seen; it has four recording keys, 1, 2, 3, 4, upon it in a
circuit, including the receiving cylinder P and the printing apparatus Q,
each being connected with a different wire R, the several parts of the
cylinder being insulated. These keys are in two pairs, with their finger
bits close together, so that an operator for cach pair can work them in
the most expeditious manner without loss of time in moving the hand
from one to the other in order to lose no time in transmitting currents
instantaneously. One operator will confine himself to the beams thrown
by the right deflections of the galvanometer and the other to the left,
each using one key for the short deflections and the other for the long
ones; thus one operator records the signals given by the positive keys
and the other those given by the negative keys, subdivided into long and
short signals.

page_text: The receiving cylinder is divided into four sections S, T, U, V, which
are insulated at W, X, Y, and it has slips Z on it representing the letters
of the alphabet in the order shown at foot of Figure 6; those letters
corresponding to the positive keys of the transmitting cylinder A. are
included in the sections V, U, with which the keys of the positive
operator, say 1, 2, at the table N connect, the one for the short signals,
with the short section U through the bearer a and metal ring b, which is
connected with all the slips in section V, and the one for the long signals
through the bearer d and the metal ring e.
The letters corresponding to the negative teeth of the transmitting
cylinder are included in the sections S, T, with which the keys of the
negative operator at the table N connect, the one for short signals with
short section T through the bearer fand metal ring 9, and the one for
the long signals with the long section S by the bearer and the metal
ring i. Although the letters or their representative slips on the receiving
cylinder are transposed in the longitudinal direction of the cylinder
relatively to the transmitting cylinder in order to group the positive and
negative ones separately they are in exactly the same relative arrange-
ment circumferentially, so that the two cylinders being revolved.
synchronously and adjusted to close and break their circuits at the
same time, it will be seen that the locally transmitted currents will
unfailingly be sent thorugh the slips on the receiving cylinder represent-
ing the same letters as the teeth on the transmitting cylinder, causing
the transmission of the currents through the cable. For example, the
teeth on the transmitting cylinder representing the letter A being single,
and arranged to act on a key in the positive local circuit, will cause the
transmission of a short positive current through the cable to the
galvanometer, where the operator for the positive signals will then send
by his positive key a current to the short section V of the receiving
cylinder, in which the letter A or its representative slips are located, and
the particular slip of the three standing for letter A corresponding to
the same one on the transmitting cylinder, A being at the moment
passing the bearer j, through which the current is passed on to the
printer, and the said connection being with the type lever for letter A,
the letter A will of couse be printed on the paper. If the tooth on
cylinder A, which causes the current through the cable, be a long one,
and the key be positive, the operater for positive signals, seeing a long
bearer on the screen, will send by his other key a current to the long

page_text: section U, where the connection will in like manner be closed through a
slip representing the letter of the transmitting key sending the long
positive signal over the cable, and so on. For each circumferential line
of slips on the receiving cylinder there is a bearer j for making con-
nection with the printer, and for each of the twenty-six letters there is a
line k in continuation of the connection, and each line connects with
a printing hammer a lever corresponding to its letter on tho transmitting
cylinder.
The printer comprises 26 printing hammers or levers 7, each with its
particular type, said hammers radiating from a common centre so as to
strike the ink pad m in the same place and press it up against the paper
strip n as it moves under the roller p, the paper strip being moved
intermittingly just previous to the striking of the hammers by the feed
rollers g, r, which are turned by a pawl moved by levers 8, t, and the
magnet u, which is also in the circuit with the transmitting keys of the
operators' table and the receiving rollers, and the printing hammers
being actuated by a lever a¹ and a magnet b' for each, also in the circuit,
the connection being by one of the wires k, with the bearer ; of the
slip of receiving cylinder representing the same letter as that of the
lever.
It will be noted that the receiving cylinder is extended in length
sufficiently beyond the length of the transmitting cylinder to make
thirty-five spaces for letters or their representative slips, and that some
of the letters (nine) are duplicated in that direction; also that the
duplicated positive letters are in one of the sections of the positive
portion of the receiving cylinder, while the duplicates are in the other
section of the same portion, and the negative duplicated letters are in
one of the sections of the negative portion, and the duplicates in the
other section of said portion; and it will also be observed that the letters
duplicated are those which occur most frequently in use.
The object is that the duplicates may be used for words in which they
are doubded or occur closely togather. To transmit more rapidly than
can be done when without duplication it is necessary to wait till the
tooth for the same letter on the transmitting cylinder comes around to
the transmitting key again.
The bearers of the duplicated letters are connected to the transmitting
wires by short wires c¹. This duplicate arrangement is also applicable
to the transmitting cylinder.

page_text: 6th. The combination of a transmitting cylinder and keys, a galvano-
meter, recording keys, receiving cylinder, and a printing apparatus,
substantially as specified.
7th. The arrangement of the positive and negative circuits through
the keys E by the insulated pieces K, I, and wires F¹ or G¹ connecting
the keys successively, according to the name of their circuit, as
described.
8th. Each lever of the printing apparatus having a special magnet b¹
and operating lever a¹ connected with the receiving cylinder and the
transmitting keys at the galvanometer, substantially as specified.
9th. The arrangement of an electro-magnet over each of the four
recording local circuit keys at the galvanometer for the purpose of
breaking the connection the instant it is completely made, and against
the will of the recording operators, substantially as specified.
In witness whereof, I, the said Alexander Melville Clark, have
hereunto set my hand and seal, this Eighth day of April,
in the year of our Lord One thousand eight hundred and seventy-
four
20 Witness,
HENRY W. DEWEY,
53, Chancery Lane,
London.
A. M. CLARK. (L.S.)