AN IMPROVED FIRE TELEGRAPH SYSTEM
Year: 1885

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I, LEWIS HARLAN M'CULLOUGH a citizen of the United States of America,
residing at No 114 North Fifteenth Street, in the City of Richmond, County of
Wayne, and State of Indiana, Inventor do hereby declare the nature of my said
invention for AN IMPROVED FIRE TELEGRAPH SYSTEM, 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 Fire Telegraph Systems and consists of improvements
in the arrangement of fire telegraph circuits whereby certain serious defects in the
existing systems are obviated.
.
It is well known that in cities and villages, that is, in those places where fire
alarm telegraph systems are most likely to be used, telephone, telegraph and other
wires in large numbers, are suspended in close proximity to one another, and that
it is not uncommon for one of them to fall upon or be blown against another. This
usually results in a derangement of one or both of the systems to which the wires
belong, which derangement is more or less complete according to the character of
the circuits employed. Besides this, other frequent causes of disturbance are the
falling of loose wires across both wires of a loop and actual breaks in the line
wires. The circuits heretofore employed in fire telegraph systems have been for
the most part a closed metallic circuit, an open earth circuit, and a closed earth
circuit.
Now, in case of an actual break in the line either of these circuits becomes
inoperative, the first wholly so, and the last two as to all the signal-boxes beyond
the point of rupture. Moreover, in the common closed metallic circuit system if
electric connection is made between the sides of a loop by a wire falling across it
or in any other way, all the boxes beyond are cut out and no notice thereof is
given. A defect of the open earth circuit, besides the one already mentioned, is
that the contact of its own wire with a telephone or telegraph wire has the effect
of shutting out all the signal boxes between the point of contact and the ground.'"
An open metallic circuit, is employed and, in practice, the signal boxes are
arranged in mutiple arc relation to one another by making a half connection to
every box from each of two wires one of which runs from the positive pole of the
battery back to the same pole again and the other of which runs similarly from
and back to the negative pole of the battery. A circuit-maker in each, box makes
L

page_text: the necessary closures of the circuit when an alarm is sent in. By this arrange-
ment it is effected that a signal will be sent in, even though the line should be
broken or otherwise defective at a single point between two stations and in case of
two or more defects in the line, only that box or those boxes will be cut out which
lie between the extreme defective points. Moreover, an accidental ground caused 5
by contact with a telephone or telegraph or other wire, will have no effect whatever
on the apparatus, while in case of the crossing of a loop, as above described, the
different engine houses will give notice of the disturbance and measures can be
taken to remove its cause.
The arrangement of the circuits will be more clearly understood by reference to 1
the accompanying drawings in which―
Fig. 1 shows schematically the arrangement of circuits; and
Fig. 2 illustrates the same as applied to a city system.
Fig. 1 illustrates a small system adapted to be used in villages. In the drawing,
W is a battery, X Z and Z¹ are the circuit wires, T T are signal-boxes normally on
open circuit and V is an electro-magnetic gong for receiving the box signals. It
will be observed that the wires X and Z the latter through the gong-magnet V, by
wire Z each run from one pole of the battery back to the same pole and that the
signal-boxes are arranged in multiple are relation between them. The advantages
of this arrangement will be set forth in connection with the description of Fig. 2.
Referring to that Figure, from one pole of the battery W, is led a wire Z¹ through
a series of engine houses Y to one terminal of a switch-board U. This switch
,board, is located in the last engine house, and is represented in the drawings as a
'plug switch board, though a switch board of any variety may be used. A loop or
loop Z, is run out from the switch board to any part of the city or village, and
when the switch board is properly plugged, the loop or loops will be electrically
connected with one pole of the battery. A "half connection" is made from each
loop to the nearest signal box T, and from the other pole of the battery a wire X
is run in the vicinity of all the boxes back to the pole from which it started and
other "half connections" made from different points of this wire to the different
'signal boxes. The circuit of any given box is normally open and remains so until
its circuit-closer is operated, whereupon the signaling mechanism operates to sound
a definite signal on gongs located in the different engine houses.
If it should be more convenient or desirable for any reason, two or more wires X,
might be run out from and back to the same pole of the battery.
It is obvious that a single break in either of the loops Z, or in the wire X, or
in each, would not interfere with the operation of the signaling apparatus, as each
box is connected in two directions with each pole of the battery; nor would two
or more breaks occuring between any two successive boxes, but two or more breaks
on opposite sides of a box or boxes, would cut out the box or boxes between the
extreme breaks, and only that box or those boxes. Other defects in the circuit
equivalent to breaks would of course operate with the same result.
Engine houses Y are shewn between the battery and the switch board. Besides
'or instead of engine houses, there may be bell towers, and in any case the wire Z¹
leads to the gong or bell magnet and passes through without break in the circuit.
The comparative size of the switch board U is exaggerated in the drawing to
show the parts more clearly.
The cross wires t t¹ are represented in the drawing as entering one at the top
and the other at the bottom of the boxes T. This is done merely for convenience
of illustration as in practice they both enter at the top.
The term "signal box" is employed in the specification to signify a circuit closing
apparatus capable, when operated, of sending a definite signal over the line. The
'advantages of the system are not confined, however, to circuits in which signal
boxes and gongs or bell magnets are, respectively, the transmitters and receivers, but
they would be equally great if any other variety of circuit closers and receiving
apparatus were' employed.

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. In an electric signaling system, an open metallic circuit, two or more circuit
closers in the same, each connected in two directions with each pole of the
generator and receiving apparatus at one or more stations for receiving the signal
when any one of the circuit closers is operated, substantially as set forth.
2. In comination with a loop or loops connected at each end with one pole of a
generator, a loop connected at each end to the opposite pole thereof, circuit-closers
arranged in multiple are between loops which are connected to opposite poles, and
apparatus at one or more stations for receiving the signal when any one of the
circuit-closers is operated, substantially as set forth.
Dated this 27th day of April 1885.
WP. THOMPSON & Co.,
Of 6, Lord Street, Liverpool,
and 323, High Holborn, London,
Patent Agents for the Applicant.