Improvements in Telegraphic Call Boxes.
Year: 1891

page_text: Date of Application, 14th Aug., 1891-Accepted, 19th Sept., 1891
COMPLETE SPECIFICATION,
Improvements in Telegraphic Call Boxes.
I, ALEXANDER MELVILLE CLARK of the firm of A. M. & Wm. Clark, of
53, Chancery Lane in the County of Middlesex, Fellow of the Institute of Patent
Agents, do hereby declare the nature of this invention (a communication to me by
Joseph Gillot Noyes of Harrison in the County of Westchester and State of
New York, United States of America) and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement
This invention relates to certain improvements in telegraphic call boxes
whereby the inadvertent transmission of an erroneous signal may be prevented;
and will be described with reference to the accompanying drawings, forming part
of this Specification, wherein
Figure 1 is an inside face view, and Figure 2 an outside face view, partly in
section, of the improved call box.
Figure 3 is a cross-section on line 3--3 Figure 1.
The same letters of reference indicate the same parts in all the figures.
The main object of the invention is to provide a call box with means
for preventing a signal being sent when the pointer D is, by inadvertence, set
beyond the correct position. For example, if, by mistake, the operator should
set the hand or pointer D to "Police" when he wants only a messenger, the
invention is to enable him to correct the mistake by unwinding the movement
without sending a signal.
To this end, an elbow lever a is connected with a pull b so that when the
pull is moved said elbow lever will be vibrated and caused to strike a pin n
on the trip-lever d and thereby to move the trip-lever d and release the move-
ment. But, at the same time that this is done, a pin e on the elbow lever a strikes
a metallic contact, as in Figure 2, which connects directly with one of the
binding posts g so that said elbow lever a being in metallic contact with the
case or box A of the instrument which connects with the other binding post h
metallically, the current is short-circuited and will not pass through the move-
ment, that is to say will not pass through the make-ând-break wheel B and
consequently no signal will be sent while the make-and-break wheel is unwinding.
When however a signal is to be sent according to the position to which the pointer
is set, the elbow lever a above referred to is not put into action but is normally kept
with its pine away from the above mentioned metallic contact f, as in Figure 1, and
in that case the trip-lever d is caused to release the make-and-break wheel B by
a crank C on the casing which crank strikes the pin n of the trip-lever and the
pull above mentioned is not used. When the instrument is operated to send a
signal, the current passes by one conductor and post into the box A and move-
ment and into the make-and-break wheel B, thence to the metallic contact spring j
of the make-and-break wheel to a conductor m leading from that metallic contact
spring to the binding post g.
It is, of course, understood that suitable clockwork connects with the wheel B
which clockwork is wound up by setting the hand D but kept from running down
and from turning the wheel B by the trip lever d until said trip-lever is caused to
disengage the clockwork and allow it to act, either by the action of the pull bor
by that of the crank C. After the trip lever d has disengaged the clock-work, the
wheel B is turned until an arm o moved by the clockwork strikes a pin p on the
trip-lever, thereby carrying the latter into its locking position, the pin r at the same
time setting the elbow lever a back to its zero position (Figure 1) if the pull has
been used.

page_text: Having now particularly described and ascertained the nature of the said
invention and in what manner the same. is to be performed, I declare that what
I claim is
1. The combination of the make-and-break wheel B and its spring with the
conductor m leading from the contact-spring to the binding post g the same binding
post connecting also. with the metallic projection which is, adapted to be brought
into contact with the pin e on the elbow lever a substantially as described.
2. A call box having means substantially as described for turning the make-and-
break wheel back to its normal position without sending a message.
3. A call box having two devices C and for moving its trip lever, one of said
devices short-circuiting the instrument to avoid sending a message, as set forth.
Dated August 14th 1891.
A. MELVILLE CLARK.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.