IM- PROVEMENTS IN FIRE ALARMS OR FIRE OR HEAT INDICATORS."
Year: 1879

page_text: LETTERS PATENT to Leon Alexandre Brasseur, Electrician, of 52, Rue de
Molenbeek, Laeken, near Brussels, and Octave Antoine Ernest Dejaer,
Accountant, of 2, Place des Barricades, Brussels, for the Invention of "IM-
PROVEMENTS IN FIRE ALARMS OR FIRE OR HEAT INDICATORS."
PROVISIONAL SPECIFICATION left by the said Leon Alexandro Brasseur
and Octave Antoine Ernest Dejaer at the Office of the Commissioners of
Patents on the 21st June 1879.
LEON ALEXANDRE BRASSEUR, Electrician, of 52, Rue de Molenbeck, Lacken,
near Brussels, and OCTAVE ANTOINE ERNEST DEJAER, Accountant, of 2, Place des
Barricades, Brussels. "IMPROVEMENTS IN FIRE ALARMS OR FIRE OR HEAT
INDICATORS."
This Invention has for its object improvements in fire alarms or fire or heat
indicators. We employ two metallic tubes of the same nature and form, the one
empty and the other full of a fusible material. They are both attached at one end
to a metallic support, so that they stand parallel the one to the other; with a small
space between them. At their other ends the tubes are connected together, but are
otherwise free. Such being the arrangement the tubes expand equally under the
influence of a slow heat, but when rapidly heated the empty tube dilates more
rapidly than the one which is full, thereby causing a deflection. The deflection
brings a contact making finger upon the free end of the tubes into contact with an
adjustable point, and so an electric circuit which may contain a bell or other call is
closed.
Under the influence of a slow heat the apparatus commences to operate on the
fusion of the material contained in one of the tubes, and this matter has been
selected to have a fusing point adapted to the climate and circunstances in which
the instrument is required to work. During the whole time of fusion the tube
containing the fusible matter will remain at the same temperature whilst the
dilatation of the empty tube continues with the gradual rise of the temperature; this
determines the contact and maintains it until the fusion is completo.
The apparatus may be rendered more sensitive by replacing the fusible material
by water, or filings of zinc, iron, copper, or other metal; but then the apparatus
will be insensible to a slow heat.

page_text: Or if the rise in temperature be too gradual to be indicated in this manner an
indication is obtained during the fusion of the material in the tube c, for during the
time occupied by this fusion the tube c will remain of a constant length, whilst the
tube b will continue to expand until a contact is brought about.
Wax or paraffin are suitable materials to employ with which to fill the tube c.
If the tube c be filled with water the instrument is rendered very sensitive to small
but rapid changes of temperature and at the boiling point; also the tube c will for
a time cease altogether to expand, whilst the expansion of the tube b will continue,
and so contact will be obtained.
The use of water will however in many cases be inconvenient, as unless the
instrument receives frequent attention the tube c will be liable to become empty by
spontaneous evaporation.
Or the tube c may be filled with a substance having a high heat capacity, and
which will remain solid at the temperatures at which the instrument is used; but in
this case an indication is obtained only when the rise in temperrture is com-
paratively rapid.
Having thus described the nature of our said Invention, and the manner of per-
forming the same, we would have it understood that we claim as our improvements
in fire alarms or fire or heat indicators our tube contact maker, substantially as
described; and also we claim the said contact maker charged with wax, paraffin, or
other solid fusible, just below the point at which the induction is desired to be
given.
In witness whereof, I, the said Octave Antoine Ernest Dejaer, have hereunto
set my hand and seal, this Eighteenth day of December, in the year of our
Lord One thousand eight hundred and seventy nine.
O. A. E. DEJAER. (L.S.)