Year: 1894

page_text: Date of Application, 14th Apr., 1894-Accepted; 1st Dec., 1894
A communication by KARL VIKTOR KARLANDER and OTTO. MEYERSON, both
of Stockholm, in the Kingdom of Sweden, Instrument Maker and Merchant,
respectively.
I, WILLIAM PHILLIPS THOMPSON F.C.S., M.I.M.E., of The Agency for
Foreign Patent Solicitors, 6 Lord Street, Liverpool and 6 Bank Street, Manchester,
both in the County of Lancaster, and 323 High Holborn in the County of Middlesex,
Civil Engineer, 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 present invention relates to a pyrometer or an apparatus for measuring high
temperatures. As in other pyrometers it is based on the disposition of bodies to
expand on heating and to contract on cooling. For the present pyrometer, air or
another gaseous fluid is used, which is not decomposed or chemically altered when
subjected to heat.
In order that the invention may be the more easily understood; the accompanying
sheet of drawings is appended, in which,
Figure 1 is a sectional elevation of the improved pyrometer, and
Figure 2 is a plan of the vacuum indicator.
The air is contained in a receiver a, Figure 1, that is placed in the room or
brought in connection with the body, whose temperature is to be measured. This
receiver communicates by means of a narrow tube b with a vacuum indicator, which
latter, as the construction on the drawing illustrates, consists of a common tubular
spiral manometer-spring c in the one fixed end of which the pipe b opens, while the
other free end by means of a suitable lever device with toothed segment and driver
actuates an index f.
When the receiver is heated, the gaseous fluid contained therein is also heated
and strives consequently to expand, by which the pressure is increased so that the
manometer-pipe is somewhat straightened and the index changes position.
The coefficient of expansion for gases being taken at about 000367 Centigrade for
each degree of temperature; if the inner pressure, at normal temperature, or at
0° C., were equal to the outer pressure of air (1 atmosphere) by heating to 2000° it
should amount to 7.34 atmospheres. To avoid such a great inner pressure, which
in many cases would have a bad effect on the instrument, rarefied air may,
according to this invention, advantageously be used instead of air of usual
density.
In order that the temperature in the vacuum indicator c may have no essential
influence on the pressure in the receiver a, whereby a wrong indication might be
given, the vacuum indicator is enclosed in a hermetically closed box d.
If W is the volume in the receiver a
V
"
"
vacuum-indicator c..
-99
P the pressure in the receiver a at 0° degrees

page_text: then
h =
P(WV) (1 + a at)
W + V (1 + at)
when a has been heated to
c still has 0%,
=
h - P.
and the difference in pressure between c and d on this occasion is
If the vacuum-indicator c and the box d are supposed to obtain a temperature (10
then the pressure in the vacuum-indicator is increased to

page_text: As these values of the temperatures in the box viz. 0° and 54,6 may be considered
as being the extreme values, it is easily understood that the temperature of the box
has no influence on the indication of the spring.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, as communicated
to me by my foreign correspondents, I declare that what I claim is-
1. A pyrometer consisting of a capillary tube b, the one end of which is formed
so as to communicate with a receiver a, while the other end is connected with a
vacuum indicator, actuated by the enclosed quantity of air or other gaseous
fluid.
2. A pyrometer, as described in Claim 1, but in which the hermetically enclosed
quantity of air or other gaseous fluid at 0° degrees has a lower pressure than one
atmosphere.
3. A pyrometer, as described in Claim 1, but in which the vacuum indicator is
hermetically enclosed in a box d in order to make the indication of the same
independent of the outer air-pressure and of the temperature prevailing in the
vacuum indicator.
Di 19th - A muil 1004
WM. P. THOMPSON & Co.,
Agents.