IMPROVEMENTS IN APPARATUS FOR ELECTRIC SIGNALLING AND ALARM GIVING
Year: 1883

page_text: "
LETTERS PATENT to John Henry Johnson of 47 Lincolns Inn Fields in the
County of Middlesex, Gentleman, for an Invention of "IMPROVEMENTS IN
APPARATUS FOR ELECTRIC SIGNALLING AND ALARM GIVING communicated
to him from Adrien Jeanjean, Commission Agent, and Louis Joseph Hippolyte
Eon, manufacturer, both residing at Paris in the Republic of France
PROVISIONAL SPECIFICATION left by the said John Henry Johnson at
the Office of the Commissioners of Patents on the 13th April 1883.
"
JOHN HENRY JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
Gentleman "IMPROVEMENTS IN APPARATUS FOR ELECTRIC SIGNALLING AND
ALARM GIVING a communication to me from Adrien Jeanjean Commission
Agent and Louis Joseph Hippolyte Eon, manufacturer both residing at Paris in the
Republic of France
This Invention relating to Improvements in Electric Signalling and alarm
giving apparatus consists in the combination of an automatic fire alarm or fire
detector and an electric signalling apparatus or bell of ordinary construction
arranged and operating as hereinafter described
According to the said Invention a thermometer is placed in connection with the
circuit of the signalling apparatus and this thermometer is so adjusted that when
a given temperature is exceeded the circuit is automatically closed notice thereof is
immediately given by means of the bell or annunciator of tho said signalling
apparatus. The employment of this alarm or fire detector in no way complicates
the arrangement or interferes with the working of the bells or signalling
apparatus
The apparatus is supported by a plate provided on one side with a pair of
contact makers or circuit closers consisting of a fixed blade connected with one of
the poles of the battery and a moveable blade bent in the form of a spiral so as to
act as a spring connected with the other pole and whose free extremity is in
contact with the under side of a suitable knob or button arranged in the cover of
17

page_text: the case containing the contact makers By pressing the button the spring or
moveable contact maker is caused to come into contact with the fixed contact
maker and close the circuit thus enabling the signalling apparatus to be worked
in the ordinary manner
In a recess or chamber at the back of the supporting plate there is provided a
thermometer preferably of a coiled or spiral form and containing mercury which
mercury is placed in communication with one of the poles of the battery by means
of a wire preferably of platinum connecting the mercury in the thermometer with
one of the wires of the signalling apparatus. In the part of the tube of the
thermometer which at ordinary temperatures is empty is arranged another wire
also preferably of platinum communicating in a similar manner with the other
pole of the battery and extending into an enlargement or swelling formed in the
said tube. The thermometer is so regulated that when a given temperature is
exceeded the mercury comes into contact with the end of the platinum wire in the
enlargement in the tube thus closing the electric circuit and actuating the bells or
apparatus for giving an alarm
The enlargement or swelling formed in the thermometer tube is provided for the
purpose of allowing the mercury to retire quickly when the temperature is lowered
so that the mercury may not be liable to adhere to the platinum wire. Holes are
provided on the circumference of the case in order that variations in the
temperature may be readily transmitted to the thermometer
The improved apparatus may be employed as a fire alarm or fire detector in
factories, hotels, private houses and other places or as an indicator of temperature
in Hothouses or Hot chambers and the like whenever it is desirable to maintain a
certain fixed temperature and is at the same time capable of being employed as
an ordinary electric signalling apparatus

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Henry Johnson in the Great Seal Patent Office on the
12th October 1883.
"9
JOHN HENRY JOHNSON of 47 Lincoln's Inn Fields in the County of Middlesex
Gentleman "IMPROVEMENTS IN APPARATUS FOR ELECTRIC SIGNALLING AND
ALARM GIVING a communication to me from Adrien Jeanjean Commission
Agent and Louis Joseph Hippolyte Eon, Manufacturer, both residing at Paris in
the Republic of France
This Invention relating to improvements in apparatus for electric signalling and
alarm giving consists in the combination of an automatic fire alarm or fire detector
and an electric bell or annunciator capable of being operated in the ordinary manner
as hereinafter described.
According to the said invention a thermometer is placed in communication with
the circuit of the said bell or annunciator the said thermometer being so adjusted
that when a given temperature is exceeded the circuit is automatically closed and
notice thereof is immediately given by means of the said bell or annunciator.
The thermometer is constituted by a tube containing mercury permanently
connected with one of the poles of the battery or generator of electricity employed
for giving the current in the apparatus. The said thermometer also contains a
wire preferably of platinum one extremity of which wire is enclosed in a swelling
or enlargement in the thermometer tube whilst the other extremity is connected
with the other pole of the generator of electricity. The distance apart of the
mercury and the wire under normal conditions is in accordance with the degree of
temperature at which it is desired to give an alarm so that when a predetermined
limit of temperature has been reached the mercury by expanding comes into
contact with the end of the wire thereby closing the electric circuit and causing
the electric bell or alarm giving device to be brought into action. The employment
of this alarm or fire detector in no way complicates the arrangement or interferes
with the working of the bells, annunciators, or signalling apparatus with which it
may be combined.
And in order that the said Invention may be fully understood I shall now
proceed more particularly to describe the same and for that purpose shall refer to
the several figures on the annexed sheets of drawings the same letters of reference
indicating corresponding parts in all the figures.
Figure 1 is an elevation of an apparatus constructed in accordance with this
Invention the cover C and push piece or button B being removed in order to show
the internal arrangements
Figure 2 is a transverse section taken along the line 1-2 figure 1 and
Figure 3 is an elevation viewed from behind, the back plate being removed.
The apparatus is supported by a plate or body part A of wood or other suitable
material provided on one side with a pair of contact makers or circuit closers
which may consist of a fixed plate connected with one of the poles of the
generator of electricity and a spring l' in the form shown clearly in figure 1 and
connected with the other pole of the generator of electricity the free extremity of
the said spring being acted upon by a suitable knob or button B sliding in the
centre of a cap or cover C screwed on to the plate A. By pressing this button B
the spring or moveable contact maker is caused to come into contact with the
fixed plate or contact maker and close the circuit thus enabling the bell or
annunciating apparatus to be worked in the ordinary manner. In a recess or
chamber D at the back of the part A. there is provided a thermometer T preferably

page_text: of a coiled or spiral form and containing mercury which mercury is placed in
communication with one of the poles of the generator of electricity by means of a
wire & preferably of platinum connecting the mercury in the thermometer with a
wire forming one of the conducting wires of the apparatus.
In the part of the thermometer tube T which at ordinary temperatures does not
contain mercury is arranged a wire y (also preferably of platinum) communicating
in a similar manner with the other pole of the battery through a wire y' forming
the other conducting wire of the apparatus. One extremity of the wire y is
contained in an enlargement or swelling t formed in the tube of the thermometer
and the distance between this wire and the mercury is so regulated that when a
given temperature is reached the mercury by expanding enters the enlargement t
and comes into contact with the end of the wire y thereby closing the electric
circuit and actuating the bell or alarm giving apparatus.
The enlargement or swelling t in the thermometer tube is provided for the
purpose of allowing the mercury to retire quickly when the temperature is lowered
so that the mercury may not be liable to make contact for too long a time.
Holes (which may be fitted or lined with eyelets or tubes) are provided in the
sides of the chamber Ď in order that variations in the temperature may be readily
transmitted to the thermometer.
This improved apparatus may be employed either as a fire alarm or fire detector
in factories, warehouses, hotels, private houses, and other places or as an indicator
of temperature in hot houses or hot chambers and the like or in any case where it
is desirable to maintain a certain fixed temperature and is at the same time capable
of being employed as an ordinary electric signalling apparatus.
Having now described and particularly ascertained the nature of the said
Invention and the manner in which the same is or may be used or carried into
effect I would observe in conclusion that what I consider to be novel and original
and therefore claim as the Invention secured to me by the hereinbefore in part
recited Letters Patent is:-
An apparatus for electric signalling and alarm giving consisting in the employ-
ment in combination with an electric bell or annunciator or signalling apparatus
of à mercurial thermometer connected with the circuit wire or wires of the said
bell annunciator or signalling apparatus in such a manner as to close the circuit
for automatically giving an alarm or signal when a predetermined degree of heat
is attained substantially as herein before described and illustrated in the
accompanying drawings
In witness whereof I the said John Henry Johnson have to this my
Specification set my hand and seal this Eleventh day of October One thousand
eight hundred and eighty three.