Improved Method and Apparatus for Determining High Temperatures.
Year: 1895

page_text: Date of Application, 26th Mar., 1895
Complete Specification Left, 27th Dec., 1895-Accepted, 26th Mar., 1896
PROVISIONAL SPECIFICATION.
Improved Method and Apparatus for Determining High
Temperatures.
I, JOHAN GUSTAF WIBORGH, of Kungstensgatan 17, Stockholm, Sweden, Professor
of the Royal School of Mines, do hereby declare the nature of this invention to
be as follows
This invention is based on the principle that if an explosive substance which
explodes at a definite temperature be enclosed in a solid body of temperature t
and this body be exposed to a higher temperature T, then the explosion of the said
substance will occur after the lapse of a definite time, the length of which will depend
on the explosion-temperature t' of the substance, on the distance of the said substance
from the surface of the body, on the heat-conducting power of the body, and on the
difference between the temperatures T and t.
If several such bodies be made of the same materials and in every way exactly
alike, it is evident that, the initial temperature t being the same, they must, when
exposed to a higher, but definite temperature T, all explode after the lapse of the
same interval of time: hence the times in which these bodies explode may be used as
a measure of the temperature T.
1 propose to give to, bodies of this kind for the determination of temperatures the
name of "thermophone."
The determination of temperatures by this method involves, of course, the loss of a
thermophone at each trial. The thermophones should therefore be made of cheap
materials, and, moreover, be of such a quality that they will neither crack nor melt
when exposed to sudden and intense heat and that they will have no injurious
effect upon metals or other materials with which they may come into contact
during use.
The explosion-temperature of the substance and the heat-conducting power of the
body in which it is contained being known, the explosion-times of a thermophone of
certain form can be calculated for different temperatures; but those times will
preferably be determined by means of an air-pyrometer. It is then possible
graphically to represent the explosion-times for different temperatures by a curve.
The equation of this curve can then be easily obtained, and the explosion-times can
thereby be calculated even for higher temperatures than it has been possible to
measure by means of pyrometers as hitherto constructed.
In this manner there may be constructed a scale which will give the temperature
corresponding to any given time of explosion.
The shape of the thermophones is to some extent unimportant; but those that
belong to the same scale of temperature must be similar. For practical reasons
thermophones that are intended for very high temperatures should be made large
ecough to ensure that exact measurements of the temperature may be made: for the
larger the thermophone, the longer is the time required to produce explosion at a
given temperature T.
The use of the thermophone is exceedingly simple. Assuming it to be of ordinary
temperature-say, from 15° to 20° C.-it is only necessary to throw it upon the
metal bath, or into the furnace, the temperature of which is to be determined, and to
carefully note, by means of a stop-watcb, the lapse of time between the instant at
which the thermophone reaches its place and that at which the explosion occurs.
This
ime being obtained, the temperature can immediately be read off on the scale that,
D

page_text: corresponds to the thermophone used.
At very high or very low air-temperatures,
when consequently the thermophone, before being used, is considerably heated or
considerably cooled, the amount by which this air-temperature exceeds or falls short
of the initial temperature t for which the scale has been constructed, should be added
to or subtracted from that given by the scale.
This new method of determining high temperatures possesses great advantages
over other methods for the same purpose, such as those in which pyrometers, metallic
alloys, "Seger pyramids," etc., are used. It is possible, for instance, without any
particular skill, to determine cheaply and quickly any temperature however high;
and in a furnace or a metal bath various parts thereof, are as a rule, accessible for the
determination of temperature by means of a thermophone. If, however, thermo-
phones are to be used in furnaces where there is much noise, or in a slag-bath
where they may sink, the explosion may be difficult to hear. In such cases thermo-
phones may be employed which contain, beside the explosive, some substance like
baryta or strontia, which, when the explosion occur, will colour the flame, so that the
explosion can be noted by sight, even if it be inaudible.
The thermophones may be manufactured of different materials, forms, and sizes,
and suitably by pressing in a mould pulverised refractory materials, either in a dry or
in a moist condition. The explosive, and, when required, the colouring substance,
ought to be situated in the middle of the body, or at its centre-line, or at a certain
distance, equal for all thermophones of the same kind, from one surface of the body.
Dated this 26th day of March 1895.
F. WISE HOWORTH,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.
Improved Method and Apparatus for Determining High
Temperatures.
I, JOHAN GUSTAF WIBORGH, of Kungstensgatan 17, Stockholm, Sweden, Professor
of the Royal School of Mines, 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 is based on the principle that if a substance which explodes at a
definite temperature t¹ be enclosed in a solid body of temperature t and this body be
exposed to a higher temperature T, then the explosion of the said substance will
occur after the lapse of a definite time, the length of which will depend on the
explosion temperature t¹ of the substance, on the distance of the said substance from
the surface of the body, on the heat-conducting power of the body, and on the
difference between the temperatures T and t.
If several such bodies be made of the same materials and in every way exactly
alike, it is evident that, the initial temperature t being the same, they must, when
exposed to a higher, but definite temperature T, all explode after the lapse of the
same interval of time hence the times, at the end of which these bodies explode
may be used as a measure of the temperature T.
propose to give to bodies of this kind for the determination of temperatures
the name of "thermophones." The determination of temperatures by this method
involves, of course, the loss of a thermophone at each trial. The thermophones
should therefore, be made of cheap materials, and, moreover, be of such a quality
that they will neither crack nor melt when exposed to sudden and intense heat and
that they will have no injurious effect upon metals or other materials with which
they may come into contact during use.
The explosion-temperature of the substance and the heat conducting power of
the body in which it is contained being known, the explosion times of thermophones of

page_text: given form can be calculated for different temperatures; but these times will preferably
be determined by means of an air-pyrometer. It will then be possible graphically
to represent the explosion-times for different temperatures by a curve. The equation
of this curve can then be easily obtained, and the explosion-times can thereby be
calculated even for higher temperatures than it has been possible to measure by
means of pyrometers as hitherto constructed.
In this manner there may be constructed a scale which will give the temperature
corresponding to any given time of explosion.
The shape of the thermophones is to some extent unimportant but those that are
intended for use in connection with the same scale of temperatures must be similar.
For practical reasons thermophones that are intended for very high temperatures
should be made large enough to ensure that exact measurements of the temperature
may be made for the larger the thermophone, the longer is the time required to
produce explosion with a given temperature T.
The use of the thermophone is exceedingly simple. Assuming it to be of ordinary
temperatures say from 15° to 20° C. it is necessary only to throw it upon the metal
bath, or into the furnace, the temperature of which is to be determined, and to
carefully note, by means of a stop-watch, the lapse of time between the instant at
which the thermophone reaches its place and that at which the explosion occurs.
This time being obtained, the temperature can immediately be read off from the
scale that corresponds to the thermophone used. At very high or very low air-
temperatures, when consequently the thermophone, before being used, is considerably
heated or considerably cooled, the amount by which this air temperature exceeds or
falls short of the initial temperature t for which the scale has been constructed,.
should be added to, or subtracted from, that given by the scale.
This new method of determining high temperatures possesses great advantages
over other methods for the same purpose, such as those in which pyrometers,
metallic alloys, "Seger pyramids" etc. are used. It is possible, for instance, without
any particular skill, to determine cheaply and quickly any temperature, however
high; and in a furnace or a metal bath various parts thereof are as a rule, accessible
for the determination of temperature by means of a thermophone. If, however,
thermophones are to be used in furnaces where there is much noise, or in a slag bath
where they may sink, the explosion may be difficult to hear. In such cases thermo-
phones may be employed which contain, beside the explosive, some substance like
baryta or strontia, which, when the explosion occur, will colour the flame, so that
the explosion can be noted by sight, even if it be inaudible.
The thermophones may be manufactured of different materials, forms, and sizes,
and suitably by pressing in a mould pulverised refractory materials, either in a dry
or in a moist condition. The explosive, and, when required, the coloring substance,
ought to be situated in the middle of the body, or at its centre lino, or at a
certain distance, equal for all thermophones of the same kind, from one surface of
the body.
In the accompanying illustrative drawings,
Fig. 1 is a cross section and Fig. 2 a longitudinal section, showing, by way of
example, a thermophone constructed according to this invention. It comprises a
cylindrical envelope or case a made of suitable refractory material such as fireclay
burnt or unburnt, and explosive material b, for example a percussion cap, which is
arranged centrally within the said envelope or case.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is
1. The herein described method of determining high temperatures, consisting in
putting into the place the temperature of which is to be determined a thermophone
consisting of an explosive substance enclosed in a solid body, noting the time which
elapses between the arrival of the thermophone at the said place and its explosion,
and ascertaining the required temperature from this time by means of a scale or

page_text: curve corresponding to the particular construction of thermophone employed, sub-
stantially as set forth.
2. Thermophones for determining high temperatures, each comprising a body of
refractory material enclosing an explosive substance that will explode at a definite
temperature, like thermophones being adapted to explode after the same interval of
time when exposed to the same temperature under the same conditions, substantially
as herein before described.
3. Thermophones for determining high temperatures, cach comprising a body of
refractory material enclosing an explosive substance, that will explode at a definite
temperature and a substance adapted to colour the flame, like thermophones being
adapted to explode after the same interval of time when exposed to the same
temperature under the same conditions, substantially as hereinbefore described.
Dated this 27th day of December 1895.
F. WISE HOWORTH,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.