Improvements in Thermometers and Thermostats for Ovens and the like.
Year: 1896

page_text: Date of Application, 3rd Mar., 1896-Accepted, 27th June, 1896
COMPLETE SPECIFICATION.
Improvements in Thermometers and Thermostats for Ovens and
the like.
We, ALLEN P. HARLAND, Manufacturer, of 14 Walnut Street Florence,
Alabama, FRANCIS MICHAEL WRIGHT, Patent Solicitor, 623 E. Street, N.W.
and DOMINGO ANTHONY USINA, Patent Office Examiner, 1814 K. Street, N.W.
both of Washington, D.C., United States of America, 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 :-
This invention relates to oven thermoscopes, being particularly designed and
adapted for use with domestic ovens.
Various devices have been provided and patented for indicating the internal
temperature of ovens, but none of them, so far as we are aware, have come into use
to any considerable extent. They have not recommended themselves either to
the manufacturer or to the buyer, because, in the first place, they have been
burdened with too great a multiplicity and complexity of parts, which not only
renders them expensive to manufacture, but also causes them to be viewed with
disfavor by the ordinary housewife or servant. In the second place, devices
hitherto constructed for this purpose have been provided with parts, such as dials,
pointers, and the like, projecting beyond the surface of the oven. This entails
additional work to keep the stove bright and clean, and the projecting parts are in
the way and are liable to be broken off or injured.
This invention therefore has been devised for the purpose of providing an oven
thermoscope in which the number of parts shall be reduced, the parts simplified,
and the cost of manufacture correspondingly lessened, and also one in which there
shall be no parts projecting outside the surface of the oven.
The invention therefore consists in the construction, combination and arrangement
of the parts devised for the above ends, hereinafter fully specified, and particularly
pointed out in the claims.
Referring to the drawing,
Fig. 1 is a front view of an oven door, provided with the improved device;
Fig. 2 is a rear view;
Fig. 3 is a front view of the indicator;
Fig. 4 is a section taken on the line 4-4 of Fig. 2; and
Figs. 5 to 10 represent diagrammatically a series of signals or pictures presented
at the opening in the stove door by the indicator in its varying positions
corresponding to the changes of internal temperature.
1 represents an even door, provided with an opening 2; 3 denotes a bar which is
pivoted at one end 4 to the inside of the oven door, and which consists of a piece of
metal sensitive to changes in temperature. The other end of this bar is pivoted
at 6 on the indicator bar 7 pivoted on the oven door at 8, and carrying at its end
the plate or indicator 9, which normally covers the opening 2 in the oven door.
In order to hold the plate or indicator 9 up against the opening 2, there is
provided a guide strip 10 which is secured upon the side of the door so as to press
apon the bar 7.
The plate or indicator 9 is made considerably larger than the opening 2 so that
only a small portion of the indicator shows at the opening, and thus by observing
the proportionate amounts disclosed of two or more contrasting colors upon the
ace of the indicator, the heat of the interior of the oven may be ascertained at a
lance with sufficient accuracy for practical purposes.

page_text: The arrangement of contrasting colors which is illustrated in the accompanying
drawing has been found to be very convenient in practice. In Fig. 3, the
face of the indicator is shown as covered with two contrasting colors, as blue and
red. In the normal position, as shown in Figs. I and 5, the line of demarcation
between the two colors will extend diagonally across the opening in the oven door.
As the temperature increases, the bar 3 expands, moving on its pivot 8 the indicator
bar, and so carrying the indicator across the opening 2. Thus as the heat increases,
more and more of one of the colors, as red, appears at the opening, indicating
to the operator the heat of the oven as determined by previous observation and
experience.
It is desirable that the distinguishing marks upon the face of the indicator, as
they are seen through the opening in the oven door, should be broad and large, so
as to be easily recognizable at a glance without close inspection, and inasmuch as
the device will often be used by ignorant and illiterate persons, it will be found
that a series of two or more contrasting colors will be more satisfactory than a
number of figures or words indicating the actual temperature of the oven.
The
selection of signs to be placed upon the face of the indicator is, however, purely
arbitrary.
Should the heat become excessive, the indicator will be moved thereby to such
an extent as to permit air to pass through the opening 2, if the latter is left
unglazed as is shown, and the indicator will thus act as a valve to reduce the
temperature within the desired limits.
The opening 2 may be formed in the oven door at the time of casting the same, so
that it will be seen that the improved device is extremely simple and inexpensive.
Moreover there are no projecting parts liable to get in the way of the operator;
there is no additional labor entailed in keeping the stove bright and clean; and
the appearance of the contrasting colors at the opening 2 somewhat enhances the
attractiveness of the stove.
While we have shown the device as applied to a door of the oven, which has
been found in practice to be preferable, it is evident that the apparatus may also
be applied to any other of the outer sides of the oven, as desired.
An important advantage which has been borne in mind in devising a simple,
economical, and commercially successful oven thermoscope has been so to construct
the apparatus that it could be applied to all existing forms of stoves and ovens
without changing the patterns of the oven door, or the part to which it is to be
applied. Manufacturers will not regard favorably the introduction of a new
device when it entails a complete change in their existing patterns, and the large
outlay of capital consequent thereupon. It is readily seen that the improved
device meets this requirement of economy, for, the only change in the casting being
the formation of the opening 2 in the oven door, this is readily effected by placing
a suitable core in the mould, without any change of the pattern. In this respect
we believe the invention to be superior to devices of a similar character hitherto
provided, as all prior devices, so far as we are aware, entail a change of the pattern
of the oven door or other part to which the thermoscopic apparatus is to be
applied.
Having now particularly described and ascertained the nature of this said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is:
1. The combination with a door, front or side of an oven or other heated
chamber, said door front or side having an opening 2, of an indicator adapted to
completely cover said opening, moving across said opening and provided with a
distinguishing mark appearing through said opening when covered by said indicator
as aforesaid and serving by its position relatively to said opening to indicate the
internal heat of the oven, and operative means whereby a change of temperature
of the oven
communicates said motion to said indicator, substantially as
described.

page_text: 2. The combination with a door, front or side of an oven or other heated
chamber, said door front or side having an opening 2, of an indicator adapted to
completely cover said opening, moving across said opening and provided with
contrasting colors the aspect of which at said opening serves by their relative
proportion to indicate the internal heat of the oven, and operative means whereby
a change of temperature of the oven communicates said motion to said indicator,
substantially as described.
3. The combination with a door front or side of an oven or other heated chamber,
said door front or side having an aperture, of an indicator moving across said
aperture and normally closing it against the admission of air, said indicator also
acting as a valve or regulator to admit air in the extreme portion of its travel,
said indicator being provided with a distinguishing mark appearing through said
opening when closed as aforesaid, and serving by its position relatively to said
aperture to indicate the internal heat of the oven, and operative means whereby
a change of temperature of the oven communicates said motion to said indicator,
substantially as described.
HERBERT HADDAN & Co.,
18 Buckingham Street, Strand, London, W.C.,
Agents for Applicants.