AN IMPROVED THERMOMETER, CHIEFLY DESIGNED FOR ASCERTAINING THE TEMPERATURE OF THE HUMAN BODY OR OF ANIMALS
Year: 1880

page_text: LETTERS PATENT to Henry Harris Lake, of the Firm of Haseltine, Lake,
& Co., Patent Agents, Southampton Buildings, London, for an Invention
of AN IMPROVED THERMOMETER, CHIEFLY DESIGNED FOR ASCERTAINING
THE TEMPERATURE OF THE HUMAN BODY OR OF ANIMALS." A communication
from abroad by the Company trading as R. and H. Mathieu, Fils, Manu-
facturers of Surgical Instruments, and Joseph Antoine Tremeschini, Engineer,
both of Paris, France.
PROVISIONAL SPECIFICATION left by the said Henry Harris Lake at the
Office of the Commissioners of Patents on the 13th November 1880.
HENRY HARRIS LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London.
" AN
IMPROVED THERMOMETER, CHIEFLY
DESIGNED FOR ASCERTAINING THE TEMPERATURE OF THE HUMAN BODY OR OF
ANIMALS." [A communication from abroad by the Company trading as R. and
1. Mathieu, Fils, Manufacturers of Surgical Instruments, and Joseph Antoine
Tremeschini, Engineer, both of Paris, France.]
This Invention relates to an improved thermometer based on the well known
principle of the difference in the coefficient of expansion of metals, which thermo-
meter is more particularly adapted for medical, surgical, and veterinary purposes.
This improved thermometer is of very small dimensions, and can easily be introduced
into the parts whose temperature it is desired to ascertain, and it is extremely
sensitive; moreover, it allows the record of the temperature which is to be
ascertained to be preserved even when the apparatus has been removed from the
place or part, as the apparatus renders the pointer or index-needle immovable, and
thereby its position on the graduated scale can be ascertained in a strong light,
and with the assistance of a magnifying glass perfectly accurate readings can be
taken. As the pointer or index needle is pressed upon the scale when it stops, the
[Duine ll

page_text: reading is not liable to be erroneous by reason of subsequent displacement of said
pointer.
A thermometer embodying this Invention consists of a supporting frame of brass
or copper having a longitudinal slot, into which a steel rod is loosely fitted. The
latter is maintained in its position on the one hand by a set screw, and on the
other hand by a notch in the support or frame, into which its pointed end takes.
At one part of its length said rod is made thinner, so as to become elastic, and to
yield in consequence of the excess of expansion of copper over that of steel under
the influence of heat.
Close to this thinned or reduced part of the steel-rod are soldered a rigid rod
and a small and very flexible rod of copper. The rigid rod acts outside a bent rod,
and the flexible copper rod acts within the said bent rod; a straight part of the
latter forms the index needle or pointer. To the bent rod a counterweight is
attached, which freely turns upon a pivot. By making the said rod bent or
knee-shaped greater play is given to the pointer.
On
The free end of the needle or pointer moves on a graduated scale, also of metal.
The parts above referred to form the thermometer, which is mounted in a metal
shell or case, to the lower part of which it is attached by means of a screw.
the exterior a metal sleeve is fitted, and closes the lower part of the case, and
facilitates cleaning of the instrument; at the other end a plug or cap is inserted so
as to slide freely in the shell or case; the said plug is provided with a lens fitted
in its top or upper part, through which lens the operator can see a magnified
image of the scale and the pointer; the lens can be screwed up or down so as to
suit the observer's sight. For throwing light upon the scale the case is provided
with an aperture or sight hole, and in a rectangular opening made in the plug or
cap a small bent transparent plate of horn or similar substance is mounted and is
brought into line with the sighthole in the shell when said plug is drawn outward.
This motion of the plug has for its further purpose to lock the pointer and to keep
it immovable in the position it occupies. This I effect as follows, that is to say:
I provide the instrument with a flexible plate, which acts as a brake and tends
constantly to bear against the pointer-bar. Said plate is moved away from the
pointer by a bent arm provided on the plug or cap, with which it engages when
the plug is pushed inwards.
Thus, when the instrument is put into the place the temperature of which is to
be ascertained the plug is pushed into the same. The pointer is then free to move
to the left hand when the temperature rises. When it is thought that equality or
equilibrium of temperature has been attained the plug is drawn out, the brake of
the pointer acts upon the latter, and the temperature it indicates is read by means
of the lens and in a strong light. By the subsequent lowering of the temperature
the outer or stiff rod above referred to moves to the right and is detached from the
bent rod which carries the pointer, and the flexible rod within the latter remains
immovable as well as the pointer, but as soon as the plug is depressed, when the
reading has been taken, the flexible rod impels the pointer, which being free.l
takes up that position which corresponds with the surrounding temperature.
Another form of this improved thermometer, which is equally applicable for
medical and surgical experiments, I construct as follows, that is to say:-
:-This
form is what is known as a "maximum" thermometer, and is made on the same
principle as the one above described.
The iron rod which forms a spring, substantially in the manner above set forth,
carries an arm which bears against a tapering bar. When the temperature rises
the iron rod stiffens, the arm is displaced towards the left hand and releases the
tapering bar, which descends. It will be necessary that the lever should be
slightly elastic, so as to yield when the temperature subsequently falls. I also
provide a stop for the said arm or lever. For reading it is sufficient to arrest
the tapering bar, and this is effected by releasing a screw which bears against a
brake, whereby the latter is free to act. Substantially the same construction

page_text: would also be suitable for "minimum" thermometers, provided the inaterials of which
the rod and the frame are made are selected accordingly, or the parts of the
apparatus are arranged in an inverted order. By placing mechanism of the kind
described to the right hand, and similar mechanism to the left hand of the iron
bar, a "minimum" and maximum thermometer would be produced.
The tapering bar may be caused to descend by its own weight, or if the
apparatus is not to be placed vertically, a small coiled spring may be provided to
exert a light traction upon the same.
Any suitable metals may be employed in the construction of this improved
therinometer.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Henry Harris Lake in the Great Seal Patent Office on the
13th May 1881.
HENRY HARRIS LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "AN IMPROVED THERMOMETER, CHIEFLY
DESIGNED FOR ASCERTAINING THE TEMPERATURE OF THE HUMAN BODY OR OF
ANIMALS." A communication from abroad by the Company trading as R. and
H. Mathieu, Fils, Manufacturers of Surgical Instruments, and Joseph Antoine
Tremeschini, Engineer, both of Paris, France.
This Invention relates to an improved thermometer, and is based on the well
known principle of the difference in the coefficient of expansion of various inetals,
which principle has been already utilized for measuring temperatures; the said
thermometer is particularly adapted for medical, surgical, and veterinary purposes. It
may be of very small dimensions and can easily be introduced into the parts whose
temperature it is desired to ascertain; moreover, it is extremely sensitive, and
allows the record of the temperature to be preserved after the apparatus has been
removed from the place or part whose temperature has been ascertained, as the
pointer or index needle may be rendered temporarily immovable with regard to its
position on the graduated scale; in a strong light and with the assistance of a
magnifying glass perfectly accurate readings can be taken. As the pointer or index
needle is pressed upon the scale when it stops the reading is not liable to be
erroneous by reason of subsequent displacement of the said pointer.
The construction of this improved thermometer is illustrated in the accompanying
Drawing, in which,-
Figure 1 is an elevation of the said instrument, and
Figure 2 a vertical section thereof.
Figure 3 is a vertical section on a plane perpendicular to that shewn in Figure 2.
Figures 4 and 5 represent the interior of this thermometer detached, the parts
being shewn in the same position as that illustrated in Figure 2.
Figure 6 shews a modified form of the said instrument.
A thermometer embodying this Invention consists, as shewn in Figure 5, of a
supporting frame a of brass or copper, having a longitudinal slot into which a steel
rod b is loosely fitted. The latter is maintained in its position, on the one hand
by a set-screw cand on the other hand by a notch at d, in the support or frame
into which its pointed end enters. At the point marked e the said rod is reduced
in thickness to render it elastic so that it will yield to the excess of expansion of
the brass over that of the steel under the influence of heat.
Close to this thinned or reduced part e of the steel-rod b, I solder a rigid rod f,
and a small and very flexible rod g of copper.
is
The rigid rod ƒ (Figures 2, 3 and 4) acts outside of a bent rod i, and the
rod (Figure 4) acts within the said bent rod i, the straight part of the latter
forming the index needle, or pointer j. To the bent rod a counterweight
attached, which freely turns upon a pivot o. By the said bent or knee-shaped
rod great freedom is given to the pointer. The free end of the needle or pointer j
moves on a graduated scale made of any suitable metal.
The parts above described form the thermometer, which is mounted in a metal
shell or case m, to the lower part of which it is attached by means of an exterior
screw ; a metal sleeve is fitted and closes the lower part of the case and serves to
facilitate the cleansing of the instrument; at the other end a plug or cap pis
inserted so as to slide freely in the shell or case; the said plug is provided with a
magnifying glass or lens o', through which the operator can see a magnified image
of the scale and the pointer j; the fittings of the lens can be screwed up or down to
suit the observer's sight. For throwing light upon the scale the case m is provided
with an aperture or sight hole r, and in a rectangular opening s in the plug or cap p
I mount a small bent transparent plate of horn or similar substance, which is

page_text: A
brought into line with the sighthole when the said plug is drawn outward.
This motion of the plug, moreover, serves to lock the pointer and to keep it
immovable in the position it occupies at the time the temperature is taken.
flexible plate acts as a brake and tends constantly to bear against the pointer-bar.
The said plate is moved away or separated from the pointer (which is then
disengaged) when the plug is pushed inward, a bent rod n on the plug engaging
with the brake-plate and raising the same.
When the instrument is put into the place the temperature of which is to be
ascertained, the plug is pushed into the same (Figures 1, 2, and 3). The pointer is
then free to move towards the left when the temperature rises; when it is
thought that equality or equilibrium of temperature has been attained, the plug
is drawn out; the brake of the pointer acts upon the latter, and the indicated
temperature is read by means of the lens and in a strong light. By the subsequent
lowering of the temperature the rod f moves to the right and is separated from the
bent rod, while the flexible rod y and the pointer remain immovable, but as soon
as the plug p is depressed when the reading has been taken the rod g acts on the
pointer, which becoming disengaged takes up that position which corresponds with
the surrounding temperature.
Another form of this improved thermometer which is equally applicable for
medical and surgical purposes is shewn in Figure 6.
This modified form of the instrument is what is known as a "maximum"
thermometer, and is made on the same principle as that above described. The iron
rob which forms a spring at a carries an arm which bears against a tapering
bar b. When the temperature rises the iron rod b stiffens, the arm is displaced
towards the left and releases the bar which descends. It is necessary that the
arm or lever should be slightly elastic so as to yield when the temperature
subsequently falls; x is a stop for the arin or lever f. For reading it is sufficient
to arrest the bar b, and this is effected by turning the screw y which bears against
a brake, thereby causing the brake to operate.
"
The same construction may be adapted for a minimum" thermometer by
inverting the order of the materials in the rod and frame, or by a left handed
arrangement of the parts of the apparatus; a double, or minimum and maximum,
thermometer may be made by making the mechanism right and left handed.
In the apparatus shown in the Drawing, the bar bis caused to descend by its
own weight; if the apparatus is to be used otherwise than in a vertical position, a
small coiled spring may be provided to exert a light traction upon the same.
Any suitable metals may be employed in the construction of this improved
thermometer.
Having thus fully described the said Invention as communicated to me by my
foreign correspondents and the manner of performing the same, I wish it
understood that I claim,-
First. The improved metallic thermometer especially designed for medical, surgical,
and veterinary purposes, and indicating the changes of temperature by means of a
pointer moving over a scale, for the inspection of which pointer and scale a
magnifying glass or lens is provided, the pointer being arranged in combination
with devices for arresting it when the instrument is withdrawn from the part
whose temperature is to be ascertained, all substantially as above set forth.
Second. The construction of the medical thermometer for ascertaining maximum
and minimum temperatures, substantially as above set forth.
In witness whereof, I, the said Henry Harris Lake, have hereunto set my
hand and seal, this Thirteenth day of May, in the year of our Lord One
thousand eight hundred and eighty one.
HENRY H. LAKE. (L.S.)