IMPROVEMENTS IN THE RECEIVING AND TRANSMITTING APPARATUS OF PRINTING TELEGRAPHS
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by William John Burnside at the Office
of the Commissioners of Patents on the 23rd April 1881.
WILLIAM JOHN BURNSIDE, of the Salisbury Hotel, Fleet Street, in the City of.
London, Gentleman. "IMPROVEMENTS IN THE RECEIVING AND TRANSMITTING
APPARATUS OF PRINTING TELEGRAPHS."
My Invention relates especially to that class of printing telegraphs which are
designed to be operated automatically by means of electric pulsations proceeding
from a suitable transmitter situated at a point more or less distant.
The general
object of the Invention is to increase the rapidity and certainty of operation of such
an apparatus, and to provide improved means of maintaining the synchronism
between the transmitting cylinder at the sending station and the type wheel at the.
receiving station or stations.
In a Provisional Specification lodged by Henry Van Hoevenbergh on the 10th
day of December 1880, No. 5162, was described a printing telegraph in which the
synchronism between the transmitting instrument at the sending station and the
type wheel at the receiving station was maintained by means of a pin fixed to the
axis of the type wheel and a detent carried by a lever arm, and which by a spring
was normally held in a position directly in the path of the pin upon the axis of
the type wheel. When the pin in its revolution came into contact with the end
of the detent, the type wheel was arrested at the zero or starting point, and there
held. If the type wheel was moving in unison with the transmitting instrument, a
pulsation of considerably more than the normal strength of current was then sent
through the line by the transmitter at the moment of passing the zero point, and
withdrew the detent and allowed the pin to pass by; but if the type wheel and
transmitting instrument were not in unison, the type wheel was arrested and held
at zero by the detent until the cylinder of the transmitting instrument in its
revolution again came to zero.
In place of this arrangement I carry the detent upon an arm which is mounted
upon one of the axes of the train of wheels of the apparatus, and is held by friction
to the axis so as to turn with it unless the movement of the arm is arrested by a
stop. Each time that the impression lever is impelled towards the type wheel, so
as to print one or other of the letters or figures on to the strip of paper, I cause
the arm carrying the detent to be turned backwards away from the axis of the
[Price 2.1

page_text: type wheel, to such a distance that the type wheel is free to make somewhat more
than two complete revolutions before the detent can come into the path of the pin
on the axis of the type wheel and stop the type wheel. In this way the apparatus
for bringing the transmitting and receiving instrument into unison will not come
into action in the ordinary course of working the instruments; but if from any
cause the instruments get out of unison, then, if the type wheel is caused to make
more than two revolutions without printing, the type wheel will be arrested at
zero and unison will be restored.
To move back the arm which carries the detent at each time of printing in the
manner above described, the arm' is made with a projection, which at each time of
printing is struck by a lever connected with the impression lever and which receives
movement from it.
In order to permit of comparatively weak currents being used for working the
escapement that controls the rotation of the type wheel, and yet obtain an effective
action of the impression lever at the time of printing, I use as described in the
Provisional Specification before mentioned a greater number of battery cells for
producing the stronger current which is to cause the movement of the impression
lever than I use for the weak alternate currents that work the escapement. To effect
this I arrange the transmitting instrument in the following manner :- -The cylinder
of the transmitting instrument is as described in that Specification loose upon its
axis, but coupled to it by a spring connection, the tension of which keeps together
two contact points, one carried by the axis and one by the cylinder. The contact
points complete a circuit through the coils of the magnetic clutch by which the
axis of the cylinder is driven from a driving wheel, and as described in the above
mentioned Specification the contact is broken when the rotation of the cylinder is
stopped.
When employing an arrangement of this kind for driving the cylinder of the
transmitting instrument, I cause the current from one pole of the battery used for
working the escapement to be led through a similar spring contact apparatus
carried by the cylinder and axis. When the rotation of the cylinder is stopped and
the circuit operating the magnetic clutch is broken, the circuit through which the
escapement was previously worked is also broken; the contact point of this
second contact apparatus being then moved away from the spring contact plate, at
the same time the spring contact plate being no longer pressed upon, springs
forward and comes against another contact point fixed on the cylinder, and through
this point a circuit is completed through a greater number of battery cells than
through the other contact which was thrown out of action, so that a strong
current is then sent to effect the printing.
This applies to apparatus working with a single line wire; if more wires are
used the number of contacts would be increased to correspond with the number of
lincs,