IMPROVEMENTS IN ELECTRIC TELEGRAPH APPARATUS, AND IN ALPHABETICAL SYMBOLS FOR USE IN TRANSMITTING TELEGRAPHIC MESSAGES
Year: 1874

page_text: ETTERS 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, AND IN ALPHABETICAL
SYMBOLS FOR USE IN TRANSMITTING TELEGRAPHIC MESSAGES."-A commu-
nication from abroad by William Edward Sawyer, of Washington,
District of Columbia, United States of America.
Scaled the 24th March 1874, and dated the 20th January 1874.
VITA
ULIC
UL the Commissioners of ratents, with his
Petition, on the 20th January 1874.
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, AND IN
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, AND IN

page_text: ALPHABETICAL SYMBOLS FOR USE IN TRANSHITTING TELEGRAPHIC MESSAGES,” to be
as follows:
-
The object of the Invention is to provide for use in ocean telegraphy
an improved receiving instrument, wherein a ray of light from any
suitable source or medium is confined and directed upon a properly
sensitized travelling tape to cause discoloration thereof in broken or
continuous lines. Also to provide a new set of alphabetical symbols,
which may be more casily, rapidly, and correctly read, and likewise
formed in less space than those heretofore employed.
The receiving apparatus consists of a galvanometer, in which a needle
is suspended by threads, and to which a cross piece or bar is attached.
The needle vibrates to the right or the left according as the current is
negative or positive. A pair of rollers or apparatus is used for moving
a photographically sensitized tape of paper, which is unwound from a
reel. An electric or carbon light is held in proper position over an eye
in the cross piece of the needle to cause a ray of light to be transmitted
through it upon the moving tape, and thus the various movements of
the needle will be accurately photographed thereon.
The limits of the movements or vibrations of the cross piece are
defined by the time the battery is thrown on the cable, but in any case
that is exceedingly brief. The. movements are recorded by connected or
disconnected angular lines or symbols.
The transmitting keys are four in number, key No. 1 giving when
pressed a long positive movement of the galvanometer needle; and
key No. 2, the short positive movement; key No. 3, the short negative
movement; and key No. 4, the long negative movement.
The points of connection are separated when the key is pressed, and
the movement of the needle is long or short according to the space of
time the points of connection are separated, or as the time required for
the key lever to pass to the regulating screw is comparatively long or
short. Tho wire passes from the earth through all the keys by their
points of connection into the cable. There is also a local positive circuit,
the current passing through the keys Nos. 1 and 2 without entering the
cable, excepting when the points of connection are separated by pressing
a key when the battery is thrown upon the cable. There is also a local 3
negative circuit operating in the same manner.

page_text: K, keys Nos. 3, 2, and 4 without pause; L, keys Nos. 2 and 3 with
pause for double length dash; M, key No. 2 with pause for treblo
length dash; N, key No. 3 with pause for double length dash; O, key
No. 2 with pause for double length dash; P, key No. 4 with pause for
double length dash; Q, keys Nos. 2, 3, and 1 with pause for dash;
R, key No. 4 with pause for dash; S, key No. 1 with pause for dash;
T, key No. 1 without pause; U, keys Nos. 3 and 2 with pause for dash;
V, same with pause for double length dash; W, same with pause for
treble length dash; X, keys Nos. 3, 2, and 4 with pause for dash ;
Y, keys Nos. 2 and 3 with pause for treble length dash; Z, key No. 4
pressed twice without pause. Period, keys Nos. 2, 3, and 1 without
pause.
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 17th July 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 Twentieth day of January, in the year of
our Lord One thousand cight hundred and seventy-four, 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, adminis-
trators, 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, AND IN ALPHABETICAL
SYMBOLS FOR USE IN TRANSMITTING TELEGRAPHIC MESSAGES," a communica-
tion to me from abroad by William Edward Sawyer, of Washington,
District of Columbia, United States of America, upon the condition

page_text: (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 immediately after
the date of the said Latters Patent

page_text: .
corrected by a fourth, and so on theoretically to any number, although
practically from five to seven currents will suffice. These alternating
currents are thus employed to control the needle and restrict it to its
normal or static condition before commencing to form the sign of a
second word or letter. Thus several movements of the needle are made
each time a word sion or signal is formed, which have no value as part
.
corrected by a fourth, and so on theoretically to any number, although
practically from five to seven currents will suffice. These alternating
currents are thus employed to control the needle and restrict it to its
normal or static condition before commencing to form the sign of a
second word or letter. Thus several movements of the needle are made
each time a word, sign, or signal is formed, which have no value as part
of the sign or signal.
The chief object or effect of the present Invention is to greatly lessen
the number of electrical impulses or currents necessary to make the sign
of a word, so that the time and expense of cable transmission may be
correspondingly diminished. By the apparatus hereinafter described
each movement of the needle is utilized in forming a signal or part of a
word, sign, or signal.
In carrying out this Invention I employ in the receiving instrument
a suspended galvanometer needle bar, having a perforation at one end,
through which a ray of light is directed upon a photographically
sensitized travelling paper, thus chemically tracing an irregular
path thereon whose variations from a straight line are greater or less,
corresponding to the oscillating movements of the needle. The length.
and direction and combination of short lines which make up the
irregular but continuous path or line on said paper strip are the indices
by which letters and words are indicated, and messages thereby
deciphered. To control the movements of the galvanometer needle I
employ as one of the chief media a cylinder, which is adapted for reci-
procating rotary movement, and provided with projecting metal strips
and teeth applied to its periphery.
When one of the keys of the lettered keyboard is pressed down on the
cylinder a metallic and electrical connection is formed, which not only
throws on the cable a current from the positive or negative pole of the
battery through the action of a local current upon the electro-magnetic
keys, but also causes an armature to engage the key and hold it in the
depressed position until the rotation of the cylinder, by means of a
peculiar arrangement of sliding pawl armature, carries it round
sufficiently far to destroy the metallic connection, when the locking
armature instantly releases the key to engage it with another that will
be similarly depressed. The length of time of engagement of the keys

page_text: and cylinder is the perfect measure of the time during which the letter
is formed. The deflection is of course changed from right to left,
and vice versa, as the current is changed from positive to negative, or
vice versa.
and vice versa, as the current is changed from positive to negative, or
vice versa.
From this general reference to the nature and operation of the
apparatus I will proceed to describe its construction and detail as far as
necessary to an understanding of the same by those skilled in the art.
From this general reference to the nature and operation of tho
apparatus I will proceed to describe its construction and detail as far as
necessary to an understanding of the same by those skilled in the art.

page_text: connected with the cable and with two local batteries, with which said
keys are normally in circuit. This circuit is broken and the battery of
either key thrown on the cable when one of the lettered keys is depressed,
as hercin-after more fully described.
The battery M is in the circuit formed through the lettered keys,
magnets GI, armature C, and springs b. (For full illustration of
connections and circuits see Figure 10.)
The spring-supported keys of board A are all pivoted on a rod a,
which is connected to the magnets of levers E, F, by wire a¹; and cach
is provided on the under side with two small friction wheels b¹,
Figures 2, 3, and 4, set at an angle to each other, and from one of which
a wire passes to the rod a, and from the other of which a wire passes to
the spiral spring 6 supporting the key. The springs are connected by
a wire and supported on a cross bar arranged beneath the keys. The
cylinder B is mounted in suitable standards or bearings, and has a crank
arm c to which are applied an adjusting screw and retracting spring
after the same manner as to armatures of electro-magnets. The long
armature D is hinged to the crank arm c, and traversing the cores of
magnets G is supported at its hooked and free end over the toothed
wheel H by a coiled spring d, as shown. When a key is depressed and
electrical connection made through the magnets G the armature D is
necessarily attracted, which causes its hook end to engage the toothed
wheel, said wheel being constantly rotated in the direction of the arrow
by spring power or other medium. The armature is thus caused to slide
over the magnets G, which carries the cylinder through an arc of
greater or less length, according to the time the key remains in contact
with it.
When the circuit is broken by the strips × on the cylinder passing
out of contact with the wheels tho armature is released from the
wheel H and the cylinder returned to its former position.
Simultaneously with the attraction of the armature D to magnets G
is the attraction of the locking armature C to its magnets I, which
causes said bar to engage the rabeted end of the depressed key and hold
it in that position till the metallic and electrical connection between the
cylinder key is broken, as before described. It will be observed from
Figure 2 that the bar C when swung forward to lock the depressed key

page_text: passes under all the other keys and prevents their being also depressed
till it moves back. Thus there is a simultaneity of action of the
armatures D and C, although for entirely different purposes. (It will
be observed the locking apparatus C is furnished with an adjusting screw
and retracting spring in the usual way.)

page_text: strips (as per arrow). The result is that while some 136 electrical
impulses or movements of the needle are requisite under the old method
to transmit the words "photographic cable telegraph," as shown in
Figure 13, only 34 impulses or movements are requisite by this
method.
It is evident that the deflection of the needle bar will continue as long
as a keyboard circuit exists through one of the levers Ę or F and that
this circuit depends in turn for its duration on the time during which
metallic contact exists between the wheels f of plates z, and the studs or
strip X on under side of the cylinder. If the contact be with a stud
of course the needle will be affected but an instant. If it be with a
strip it will necessarily be longer, but will vary with the length of the
strip. Thus the studs and strips X' determine absolutely the length of
time or extent of deflection of the needle. The strips × on the upper
side of the cylinder have a different function, which is to determine or
regulate the time during which a key is held locked by armature C, and
thereby determine the length of the dashes formed on the paper strip or
tape, which are not formed by electrical currents, but by the forward
movement of the strip or tape.
The dash is always part of a letter and the length of a dash in con-
nection with the oblique movement caused by the galvanometer needle
determines the letter; as for instance a short positive movement of
needle, to which is added a brief dash, means one letter, and a longer
dash another letter, and with a still longer dash another letter.
In other words the circuit through a lettered key and the cylinder
strip beneath it through pawl armature D, magnets G I, locking
armature C, and battery M, exists independently of and continues after
the circuit formed through the same key and one of the keys E F, and
prevents, for the time being the release of armature C and depression
of another lettered key.
Having described the nature of the Invention and the manner of
performing the same, I declare that what I claim as the Invention to be
protected by the herein-before in part recited Letters Patent is,-
1st. The combination with the lettered keys having an end shoulder
or rabbet, as shown, of the vibrating locking armature C, the same

page_text: 9thly. The mode of transmitting telegraphic signals by means herein
lescribed.
In witness whereof, I, the said Alexander Melville Clark, have here-
unto set my hand and scal, this Seventeenth day of July, in
the year of our Lord One thousand eight hundred and seventy-
four.
Witness,
HARRY SAALES,
53, Chancery Lane,
London.
A. M. CLARK. (L.S.)