Improvements in Temperature Indicators.
Year: 1892

page_text: Date of Application, 14th June, 1892-Accepted, 27th Aug., 1892
COMPLETE SPECIFICATION.
Improvements in Temperature Indicators.
I, HARVEY MURDOCK of 11, Montgomery Place, Brooklyn, in the County of
Kings and State of New York, United States of America, Inventor, do hereby
declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:
My invention relates to improvements in temperature indicators and especially
devices of this kind which are adapted for use in ovens and similar places where it
is necessary to keep a high and substantially even temperature.
It is well known that the temperature of baking ovens is usually guessed at to
a certain extent and consequently it is a difficult matter to properly bake many
articles which require an exact given temperature and the object of my invention
is to produce an extremely simple apparatus, which may be easily and cheaply
applied to any oven and which will automatically indicate the exact temperature of
the oven, thus reducing the operation of baking from a mere matter of guesswork
to a scientific operation. A further object of the invention is to produce a simple
instrument which will operate by its own expansion directly upon the index or
indicator proper without the use of levers of any kind as it is a well known fact
that there is usually more or less lost motion in lever systems and that they are
consequently inaccurate. To this end my invention consists in a temperature
indicator, the construction of which will be hereinafter described and claimed.
Reference is to be had to the accompanying drawings, forming a part of this
Specification, in which similar figures of reference indicate corresponding parts in
both views.
Figure 1 is a face view of the indicator as applied to an ordinary range and
Figure 2 is a broken sectional view on the line 2-2 in Figure 1 shewing the
entire apparatus and more particularly the mechanism for operating the indicator
hand.
In the drawings 10 represents a common form of range having the usual oven 11,
and extending transversely through the oven near the upper part of the same is an
expansible rod 12 which has near its inner end a screw thread 13 held to turn in a
correspondingly threaded hanger 14 which is secured to the top wall of the oven.
The outer end of the expansible rod extends through a perforation 15 in the wall
of the range and at the extreme end of the bar is a laterally-extending
indicating hand 16 which moves over a circular dial 17 secured to the wall and
forming a bearing for the bar, the dial being marked off into degrees after the
manner of an ordinary thermometer.
It will thus be seen that when the bar 12 begins to expand under the influence
of heat, it cannot move bodily in a longitudinal direction, but this expansion
will cause the threads 13 to act on the threaded hanger 14 so as to revolve the
bar and the hand 16 will thus be caused to move over the indicating dial 17.
It will be understood that as the temperature rises the expansion will increase
and the rod be turned a greater distance and consequently that the indicating
hand 16 will move in direct proportion to the expansion of the rod and will thus
in connection will the dial accurately indicate the temperature of the oven.
Instead of producing the thread on the inner end of the rod 12 it may be
provided with simple projections which will enter the thread in the hanger 14
and cause the rod to turn, and instead of having the dial 17 stationary and the
hand 16 revolve, the dial may be caused to turn with the rod and the hand be held
in a stationary position.
From the foregoing description it will be readily understood that this instrument

page_text: may be applied to any kind of an oven and that it will always accurately indicate
the temperature thereof. It will also be understood that the expansible screw
threaded bar may be applied to any place where the heat varies greatly, and made
to operate an indicator or other device.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is―
1. A temperature indicator for ovens, comprising an apertured hanger for the
interior of the oven, an expansible and revoluble rod passed through the said
hanger, a screw thread connection between the rod and the hanger to cause
the former to rotate in the latter, upon expanding, and indicating devices for
the exterior of the oven, operated by the said rod, substantially as set forth.
2. The combination, with an oven having an indicating dial on its outer
wall and a threaded hanger within, of an expansible rod having one end
screw threaded and adapted to fit the hanger and the opposite end journaled in
the dial and provided with an indicating hand, substantially as described.
3. A temperature indicator constructed and arranged to operate substantially
as shewn in the accompanying drawings and described in the foregoing Specifi-
cation.
Dated this 14th day of June 1892.
H. MURDOCK,
By A. M. & Wm. Clark,
53, Chancery Lane, London, Chartered Patent Agents.