IMPROVEMENTS IN AUTOMATIC FIRE ALARMS
Year: 1874

page_text: PROVISIONAL SPECIFICATION left by Thomas Hughes at the Office
of the Commissioners of Patents, with his Petition, on the 14th
October 1874.
I, THOMAS HUGHES, of Gracechurch Street, in the City of London, do
hereby declare the nature of my said Invention for "IMPROVEMENTS IN
AUTOMATIC FIRE ALARMS," to be as follows:-
My Invention relates to automatic fire alarms, and is intended to give
in any room or portion of any descripton of building an alarm when
another or distant part of the said building is on fire or about to become
80. It consists of two distinct parts, the first part containing the bell
with its retaining or releasing levers for giving the alarm, which part may
be fixed in any portion of a building as heretofore mentioned where it
may be deemed necessary or expedient to arouse the attention of the
person in charge.
The second portion of the apparatus for actuating the levers and bell
may be placed in any room, passage, or staircase, or in any part of the
building where a fire is most likely to occur, or if necessary may be
placed in every separate part or portion of the building, the several
it

page_text: portions communicating with one bell or alarm by wires and chains if
not desired to use more than one of the latter.
.
The hammer of the bell or alarm is worked by means of a coiled
spring and three toothed wheels, one of which being an escapement will
readily move and work the hammer for a definite time.
When wound up the hammer is retained or held back by a small catch
lever which is attached at one end of a rod or spindle, on which are
placed a number of smaller arms or levers corresponding in number
and leading by wires or chains to the various apartments to be
communicated with, so that until a fire actually takes place in one of
these rooms the ringing apparatus remains normally wound, or the spring
thereof coiled tightly up.
The second part or actuator is composed of a tube made of brass, zinc,
tin, or other suitable material, around which is a collar or holder on
which the tube is held, or suspended vertically in a suitable bracket
attached to the wall or ceiling. Inside the lower end of the tube a
washer, disc, or perforated plate of metal is placed and is acted upon by
the heat as hereafter described. This metal is composed of 4 ounces of
bismuth, 2 ounces of lead, and 1 ounce of tin, or thereabouts, as may
be found most suitable, the compound readily yielding to the heat at
about 140 degrees Fahrenheit. Inside the tube and resting on the
compound metal disc is a weight; when undue heat arises in any room
or part of the building where the tube is fixed the said metal disc melts
and the weight falls down through the bottom of the tube bringing with
it the chain which attaches it to the various cranks in connection with
the bell or alarm, and so communicates to the wires a sharp sudden pull
similar to that given by an ordinary pull of a street door or room bell.
As the weight falls it tightens the wire and pulls that arm or lever on
the rod or spindle of the apparatus corresponding to the particular room
or part of the building where the fire originates, the effect of which is to
partially turn the rod or spindle and pull back the lever, retaining the
hammer of the bell, which being released the spring at once uncoils, and
by so doing the hammer produces the same effect on the bell as is
produced by the alarm of an ordinary clock, only that it will be much
louder and will last longer.
In other cases the weight may be suspended by lengths of copper wire
linked together by the before-mentioned metal at, say, intervals of about
12 inches apart. This wire would be fixed in a small eye at one end of

page_text: the apartment, and would stretch along the ceiling to the other end
thereof, the weight in that case being upheld by a hook attached by a chain
to the wire, so that in the event of any part of the wire being subjected
to a more than ordinary heat the bismuth link nearest the heat would
be melted and the weight released with the results before-mentioned; or
where there would not be sufficient room or where it would not be
deemed expedient to fix a weight, the same result can be obtained by
means of an ordinary spiral spring such as now used for ringing bells or
other alarms.
I also. propose in the case of stables, hay lofts, warehouses (such as
pantechnicons), large mills, granaries, or wherever extensive quantities of
goods of inflammable nature are stored to use lengths of iron or other
metal barrel or pipes connected together the whole length of the building,
and to run a similar wire as before described through these tubes and
connected with the weight or spring to strike a bell thereby. In the
case of docks, warehouses, or granaries, these pipes can be laid in between
the merchandise at intervals of as many feet apart as many be considered
necessary to give information when the various parts are overheating
from spontaneous combustion or other causes, thus preventing such
frequent calamities as have occurred in many large warehouses, &c.
Hay or stacks of any other description may also be fitted with these
movable pipes in which cases it would not be necessary to have a bell,
but merely take the falling of the weight for an indicator that the stack
or rick is overheating or rotting itself.
If desired to save expense the ordinary door bell or alarm may be used
in connection with the retaining levers and rod, and with the second part
of my Invention in lieu of the alarm or ball before described.
A modification of the second part of my Invention may be made by
substituting for the compound metal disc a retaining lever to the weight,
the said lever being in connection with a piston which is normally at rest
in a tube containing quicksilver, glycerine, and water or other suitable
fluid, but which on the expansion of the quicksilver or other fluid
from the action of undue heat rises and releasing the lever from the
weight causes the latter to fall as before.