IMPROVEMENTS IN ELECTRO-TELEGRAPHIC APPARATUS, AND IN INSTRUMENTS FOR PREPARING THE TRANSMISSION OF ELECTRIC TELEGRAMS
Year: 1864

page_text: PROVISIONAL SPECIFICATION left by John McElroy at the Office of
the Commissioners of Patents, with his Petition, on the 13th June
1864.
I, JOHN MCELROY, of Stretford, in the County of Lancaster, Book-keeper,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
ELECTRO-TELEGRAPHIC APPARATUS, AND IN INSTRUMENTS FOR PREPARING THE
TRANSMISSION OF ELECTRIC TELEGRAMS," to be as follows:-
:
The first part of this Invention consists chiefly of an arrangement of apparatus
for transmitting and receiving electric telegrams in conjunction with relays at
the distant station, whereby both positive and negative currents can be used,
instead of currents of one kind only, to print the characters employed, and
with a lesser number of line wires than have hitherto been used, without the
necessity of passing over the length of the type or other transmitting agency
more than once. Either three or two line wires may be used, type or a per-
forated ribbon of paper being employed in the transmission of signals.
In the case of three line wires being used, with type, five levers are
employed, two of which work the keys of a battery of one of the line wires,
two other of such levers working the keys of a battery of another of the lines,
and the remaining lever working a key which brings the third line wire into
communication with a battery. The terminal points of the said levers are so
arranged that when the types are moved forward to them in the act of trans-
mitting a message, three of the levers only shall be raised, whilst the type
piece is passing its length and currents sent along the wires in one direction;

page_text: but immediately the type piece has passed the end of the said three levers, the
remaining two levers are in their turn raised by the type piece, and contrary
currents sent along two of the wires. At the distant station two relays are
worked by the two wires sending alternate contrary currents, each of the relays
establishing electric currents along one or other of two wires connected with
it (which wires are in direct communication with the printing apparatus),
according as positive or negative currents are transmitted. The third line
wire is connected direct to the printing apparatus without the intervention of a
relay. There are thus five printing wires, one in direct, and the other four in
indirect communication with the transmitting apparatus. When the foremost
three levers are raised by the type piece sending currents in one direction,
three of the printing wires will have currents established in them, and when
afterwards the remaining two levers are raised, currents along the remaining
two printing wires will be established. The terminal points of the printing
wires are so arranged that those two which are actuated by the two transmitting
levers last raised by the type piece, are placed just so far in advance of the
other three terminal points on the moving strip of paper which receives the
telegrams, that when the electric current is stopped in the three printing wires,
the paper will have moved just the distance between the two sets of printing
points, and the two printing wires having in their turn received their currents,
the marks printed on the paper fall into their proper places to print the
required letter or character as transmitted. In this manner the printing of
each character is divided into three parts; by the first three currents the
upper, central, and lower parts are printed, and by the following two currents
the intervening parts are printed.
When a ribbon of paper is used, a series of needles is placed above in con-
nection with the batteries, and a row of thin metal plates, terminating in flat
surfaces below in connection with the earth and line wires. The strip of
paper passes between the needles and the thin metal plates separating them,
so that when the perforations in the paper are moved forwards, there will be
transmitted, as in the previous case, first three currents in one direction,
and afterwards two in the contrary direction.
When two line wires are used, apparatus similar to that before described is
employed, but in this case the printing of each letter is divided into three
parts, levers, transmitting needles, and printing points being arranged accord-
ingly. The first part of each character is formed by two positive currents,
and the second by two negative currents, or vicè versa; the third part being
formed by a positive current along one wire, a negative current being sent along
the other wire at the same time. To take advantage of this, two relay needles

page_text: are placed side by side, a small arm being fixed on each needle at right angles
thereto. A cross piece, fixed to a spring in metallic communication with the
fifth printing wire, is placed between the needles, such cross piece being free
to turn on its centre. When the relay needles both move in the same
direction, the spring will not be affected, because the cross piece will only be
turned round its centre by the arm of one of the needles pressing upon it, but
when the needles move in contrary directions by reason of contrary electrical
currents, then both the arms will press on the cross piece, and the spring will
be forced down into communication with a battery, and the current transmitted
along the fifth printing wire, thus effecting the printing of the final part of the
character.
The second part of this Invention consists of an instrument for punching or
cutting the holes in strips of paper used for transmitting electric telegrams.
Two axles are mounted in a framework, the same being connected by spur
wheels gearing into each other. On the peripheries of drums mounted on the
axles are fixed two corresponding sets of punches or dies. On one of the axles
is fixed a hand which moves over the face of a dial, the latter having inscribed
thereon the characters employed, corresponding to the punches. On the
drums being brought into proper position by the hand, as indicated by the
dial, one of the punches will be forced upwards by the pressing down of a
lever on to the paper, and the punching effected; and by the same action a
catch is thrown forward to a ratchet on one of the guide wheels, and the
paper drawn forward sufficiently to receive the punching of the next letter or
character.