IMPROVEMENTS IN THE METHODS AND APPARATUSES FOR INDICATING TEMPERATURE
Year: 1878

page_text: LETTERS PATENT to Joseph Ducomet, of No. 20, Rue des Petits Hotels, Paris,
in the Republic of France, Engineer, for the Invention of "IMPROVEMENTS IN
THE METHODS AND APPARATUSES FOR INDICATING TEMPERATURE."
COMPLETE SPECIFICATION filed by the said Joseph Ducomet at the Office of
the Commissioners of Patents on the 5th September 1878.
"
JOSEPH DUCOMET, of No. 20, Rue des Petits Hotels, Paris, in the Republic of
France, Engineer. IMPROVEMENTS IN THE METHODS AND APPARATUSES FOR
INDICATING TEMPERATURE."
My Invention consists in a new method and apparatuses for indicating tempera-
ture, and for giving notice by means of a signal the moment that a given
temperature has been reached; and for this purpose I make use of the fusion of a
metallic or other body, and alloys or mixtures of these bodies.
In the accompanying Drawing, Figure 1 represents one of the apparatuses I
employ for carrying out my Invention.
A, A, is a box enclosing the mechanism (which is shewn in section at Figure 2),
and a circular spring B, C, D, fixed at its ends at a and b, on the support c. A rod
E, F, G, of metal, earthenware, or other suitable material is fixed to a rack H
attached to the spring B, C, D, by means of the screw d; the rack gears with the
pinion e, carrying a needle or hand.
At the end of the rod E, F, G, are fusible discs f, g, h, i, j, the weight of which
bends the spring B, C, D, as shewn in dotted lines. An envelope or casing I, J, K,
of metal or earthenware encloses the whole. The instrument is fixed either with or
without a joint by means of the thimble or flange L. The union & serves to allow
of charging the instrument, and of replacing the melted washers or discs, several
openings l, m, n, facilitating the circulation of the air above and preventing the
heating of the apparatus.

page_text: The part J, K, being in the furnace or fire, let it be supposed that the washer or
disc is of tin, g of lead, h of zinc, i pure antimony, j'brass. The washer will
melt at 480 degrees Fahrenheit, and the rod being relieved of this weight will rise a
certain distance, moving the hand, which would then indicate this degree of tempe-
raturo on the dial. The disc g will melt at 626 degrees Fahrenheit, and in the
Bame manner the needle will indicate a corresponding temperature, and so on for
other discs, videlicet, 815 degrees for the zinc disc, 1274 degrees for the antimony,
and 1652 degrees for the brass.
Any other suitable substance than the herein-before described metals may be
used.
Figures 2, 3, and 4 represent a modification of my apparatus.
As in the herein-before described arrangement the rack is prolonged by a guided
rod A', A¹, A', enclosed in a tube B1, B2, B, and traverses a stopper C, closing the
end of the tube, and is terminated by a knob C. A series of holes allows of intro-
ducing pins of materials fusing at different known temperatures.
The pins a¹, b, c, d, e, f, being placed in the holes, the spring is stretched, and
will be deflected to a given extent each time a pin melts, and the needle will be
moved over the dial as herein-before described. The pins should be placed in the
order of their fusibility, the most fusible being placed at the top.
Figure 5 shews the channelled guide hole for facilitating the running off of the
melted metal, which might remain there engaged in the pin hole.
This instrument may be placed in any position and requires but little metal.
In Figures 19, 20, and 21 I shew a spiral spring enclosed in a barrel, and
actuating a needle; it carries a wheel a³, into which gears a rack v³, forming part of
the rod y carrying the discs or pins. The action of the apparatus is the same as
that herein-before described.
When it is not necessary to protect the rod by means of a tube, I adopt the
arrangement shewn in Figures 6, 7, 8, 9, and 10, which consists (see Figures 6, 7, 8)
of a plate hollowed in the middle, or (as in Figure 9 and 10) of a similar plate with
the ends bent over at right angles.
In Figure 9 the fusible pins are replaced by screwed nuts i, j, k', of fusible mate-
rial like the pins.
In Figure 11 the moveable rod is furnished with a cap for receiving a liquid,
the weight of which will bend the spring and the evaporation of which will produce
the same results as the melting of the discs. Suitable openings allow of the dis-
charge of the vapour.
In Figure 12 the cap is replaced by a small basket m', perforated with a largo
number of holes; in the basket is placed any suitable material melting at a low
temperature, such as wax.
Figure 13 shews the same basket furnished with a closed or perforated cover.
The weight of the baskets and their contents act in the same manner as that herein-
before described, and produco the same effects on the needlo.
Figure 22 represents the same basket, the bottom of which is formed of a piston
attached to the rod; in proportion as the contents of the basket escapo by melting,
the piston and the rod rise, moving the needle.
In Figure 14 the melting part is the screw n³, and n³ is simply glue.
When the screw disappears or melts, the glue falls and the rod rises.
In Figure 15 the fusible discs are replaced by tubes.
In Figures 16, 17, and 18 a spiral spring D is enclosed in a cylindrical box
o', p, q, and the ordinary rod P, carrying the fusible substances, traverses it and is
united to a plate Q, under which is the spiral spring. In proportion as the pins
melt the index rises and shows on the scale R the corresponding temperature.
Instead of springs, weights or other equivalent means may be employed.
An electric, pneumatic, or other alarum may be adapted to my improved instru-
ments. The upper end of the rod may be provided with a point, and on rising this
point will strike a percussion cap so as to ignite a small charge of gunpowder.
Having thus described my Iuvention, and the manner of performing the same, I

page_text: wish it to be understood that I do not confine myself to the preciso details herein
laid down, as the same may be varied without departing from the peculiar character
of my Invention, but what I do claim is,-
Firstly. The utilizing the fusion or the evaporation of substances or bodies for
indicating certain fixod temperatures, as herein-before described.
Secondly. The peculiar construction of the apparatuses herein-before described,
and shewn in the Drawing, for utilizing the fusion or evaporation of substances or
bodies in combination with their employment as weights or as impediments acting
on a spring or its equivalent, and on a needle or other suitable index for showing
externally the changes in the state of the bodies or substances employed, such
changes corresponding with fixed temperatures.
In witness whereof, I, the said Joseph Ducomet, have hereto set my hand and
seal, this Thirtieth day of August, in the year of our Lord One thousand
eight hundred and seventy-eight.
J. DUCOMET. (L.S.)