IMPROVEMENTS IN THERMOMETERS
Year: 1884

page_text: I, JAMES MURRIE, of No 206 Gallowgate, Glasgow, in the County of Lanark,
North Britain, Engineer do hereby declare the nature of the said invention for
IMPROVEMENTS IN THERMOMETERS to be as follows:-
This Invention, which relates to Improvements in Thermometers more especially
designed for measuring high temperatures, is a further development of the new or
improved Thermometer for which a Patent was applied for by the said James
Murrie No 9393, of the 25th day of June A.D. 1884.
Under the present Improvements the Thermometer is made to contain a com-
paratively long column of mercury, the length of the said column of mercury being
sufficient to produce a pressure whereby the boiling point of the mercury is raised
to the necessary extent.-The column of mercury may in cases where it is desired
to indicate temperatures at a distance from the point whose temperature is being
observed be subdivided into two, three, or more columns of mercury which occupy
the lower parts of one or more U shaped tubes continuous with the tube which
contains the first or long column of mercury.-Between each column of mercury
and occupying the upper parts of the U shaped tubes, water or other fluid is placed
and the indicating scale is marked on or attached to the last vertical member of
the U shaped tubes which member for the purpose of observing the mercury
readings on the scale is made of glass.-The upper end of the tube whether a single
vertical tube be used with or without one or more U shaped tubes may or may not
be provided with a chamber in which pressure is generated by the expansion of
the mercury, and the improved Thermometers may be provided with Bourdon or
other pressure gauges whereby the pressure of the fluid due to the expansion of the
mercury is indicated simultaneously with the temperature.
The Thermometers herein before described as well as the Thermometer described
in my aforesaid Provisional Specification may have combined with them any
convenient form of alarm apparatus which is set into operation by the expansion
of the mercury when it has reached a particular or set point.

page_text: JAMES MURRIE, 206 Gallowgate Street Glasgow county of Lanark, North
Britain, Engineer do hereby declare the nature of my invention for IMPROVEMENTS
IN THERMOMETERS and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement:-
My Invention, which relates to Improvements in Thermometers more especially
designed for measuring high temperatures, is a further development of the new or
improved Thermometer described in my Complete Specification N° 9393 of the
25th day of June A.D. 1884.
Under the present improvements the Thermometer is made to contain a com-
paratively long column of mercury the length of the said column of mercury being
sufficient of itself to produce an initial pressure whereby the boiling point of the
mercury is raised to the necessary extent.-The column of mercury may in cases
where it is desired to indicate temperature at a distance from the object or part of
an object whose temperature is being observed, be subdivided into two, three or
more columns of mercury which occupy the lower parts of one or more U-shaped
tubes continuous with the tube which contains the first or long column of mercury.
Between each column of mercury and occupying the upper parts of the U-shaped
tubes, water or other fluid is placed and the indicating scale is marked on or
attached to, the last vertical member of the U-shaped tubes, which member for the
purpose of observing the mercury readings on the scale is made of glass.-The
upper end of the tube whether a single vertical tube be used with or without one
or more U-shaped tubes may or may not be provided with a chamber in which
pressure is generated by the expansion of the mercury, and the improved thermo-
meters may be provided with Bourdon or other pressure gauges whereby the
pressure of the fluid due to the expansion of the mercury is indicated simultaneously
with the mercury.
The Thermometers herein before described as well as the Thermometers described
in my aforesaid complete specification may have combined with them any con-
venient form of aların apparatus which is set into operation by the expansion of
the mercury when it has reached a particular or set point.
In order that my said Invention may be understood and readily carried into
effect, I will proceed to describe the drawings herein annexed.
Fig. 1. is a front elevation of a form of Thermometer adapted for being applied
to an oven or other chamber, wherein temperature is indicated by the position of
the mercury within such instrument. Fig. 2 is a front elevation of an Instrument
also adapted for measuring or indicating heat in an oven or other chamber, wherein
the temperature is read by the position of the mercury in the transparent tube
and also by a pressure gauge. Fig. 3 is a front elevation of an instrument adapted
for portability or hand use, wherein the temperature can either be read by the
position of the mercury or by the pressure gauge. Fig. 4 is the side elevation of
an instrument wherein the temperature is read off at a distance from the heated
body.
I will now describe fully the construction of these Instruments. In Fig. 1,
which is mainly applicable to ovens where the instrument has to be inserted thro'

page_text: a side wall or partition, the expansion chamber A is constructed of steel or well-
hammered wrot iron. The expansion chamber A is connected to the tube B by
means of a screw or weld, the tube B which also consists of Steel or Iron is made
of sufficient length to pass thro' the partition wall of the oven and is made to form
part of the vertical tube "C" by being bent to the desired angle, the vertical
tube "C" is connected at the top to a transparent tube "D" by means of glands
and washers all as described in my aforesaid complete specification 93934. The
transparent tube "D" may be made of common barometer tubing, sealed at the
upper end, and having graduated plates or scales attached. Fig. 2 is practically
the same instrument as already described under Fig. 1 but fitted in addition with
a pressure gauge of the "Bourdon" type, or any other known pressure indicator.
Such indicator being intended for the higher range of indications, say over
400° Fahr. The chamber A is in this instance shown of a more elongated form,
with the object of exposing it to a greater heating effect, and the obtaining
average indications of heat instead of at one point. When the Instrument is
employed only to indicate temperatures above say 400° Fahr, the transparent tube
and scale may be dispensed with, the gauge being coupled on or attached to the
extremity of the vertical tube "C" care being taken that sufficient water be
placed between the mercury and the gauge to prevent the latter entering and
destroying the gauge.
Fig. 3 is mainly applicable to caustic pots & other boilers where the Instrument
can pass or enter the vessel in a vertical direction, the expansion chamber A may
be constructed as described in the aforesaid complete specification, or if preferred
by coiling the extreme end of the vertical tube "C" spiral fashion as shewn in
the figure. Such having the advantage in there being less joints. The remaining
parts of the instrument are practically duplicates of the Instruments described
under Figs. 1 and 2. For portable purposes the top part may be provided with
a handle of any convenient form attached to the Gauge. Fig. 4 is mainly adapted
for Indicating temperatures some distance away from the heated body, the vertical
tube "C" has attached to it another tube, or the tube "C" may be continued in
a horizontal or in any desired direction, in a straight line as shewn, or bent in the
form of a U tube or tubes such tube "F" having the pressure gauge placed at or
near its extremity, the object being to remove the Indicator clear of the heated
body to any desired point for observation.
The apparatus hereinbefore described may be provided with casings charged
with some non-conducting material as described in the aforesaid complete specifi-
cation, or if preferred may be plated with copper or other material which prevents
oxydation.
"
The action of these Improved Thermometers is as follows. The expansion
chamber "A as well as the connecting tube. "B" are filled with mercury, the
vertical tube "C" is also filled with mercury wholly or with another liquid in
addition on the top part of the mercury, the transparent tube being filled with an
elastic fluid such as common air or other fluid, and the gauge when attached has
between it and the mercury a sufficient body or column of water or other liquid
to prevent the mercury coming in contact with the mechanism or mechanical parts
of the gauge. On taking measurements of temperature the expansion chamber or
bulb is subjected to the action of the heat, the mercury in consequence re-acting
hydrostatic fashion throughout the liquid in the Instrument has the pressure
transmitted to the Indicator. On approaching the temperature at which the
mercury would boil under normal conditions, the mercury in this case has either
sufficient pressure acting on it to prevent ebullition, or has in the act of expanding
generated sufficient pressure in the expansion chamber A. to raise the boiling point
& thus prevent boiling or ebullition of the liquid. The pressure necessary to
prevent ebullition corresponds to the pressure generated by the boiling of the
mercury and the creating of saturated vapour, hence the mercury may " vaporize
but not "boil" in the aforesaid apparatus without affecting the accuracy of the
Indications.
"

page_text: Having explained the construction and action of these Improved Thermometers
I now describe the new or novel features embodied in their design. The mercury
in the apparatus where subjected to heat is maintained in a liquid condition without
boiling or ebullition, even altho' the temperature be much greater than would lead
to the mercury boiling under normal conditions. The greatest tendency to boil &
being in the comparatively small body of the apparatus between the expansion
chamber and the connecting tube outside the oven or heated vessel, boiling or
ebullition of the mercury at that point or part is prevented by creating an initial
pressure on the mercury at or near that point, hence the connecting part of the
stem can also be subjected to the action of the heat without the accuracy of the 1
indications being affected.
The apparatus being charged with liquids, and these liquids being prevented
from boiling, it follows that the pressure generated in the expansion chamber, is
transmitted thro' the aforesaid liquids in every direction, and the friction being
infinitesmal it also follows that the pressure can, by employing a comparatively
long column of a liquid, be transmitted to any distance and in any direction to an
indicator placed at the terminal, without affecting the accuracy of the indications
to any perceptible extent. It also follows that the Indicating apparatus can by
the foregoing means be removed sufficiently clear of the heated body to entirely
obviate any inaccuracy due to the heat affecting the Indicating apparatus.
No vapour of mercury can find its way into the stem or connecting tube, or can
be generated in the connecting tubes, hence the tendency to obtain inaccurate
readings thro' the vapours becoming superheated or partially condensed is in this
case entirely obviated.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
(1) First. The extending the range of a mercurial thermometer through main-
taining the mercury in a liquid condition without boiling or ebulliton by means of
the apparatus constructed substantially as herein before described.
(2) Second. The use of a thermometer, combined with a pressure gauge wherein
the mercury in the expansion chamber is in direct unbroken contact with the
mercury in the connecting tube or tubes leading to the Indicator all as hereinbefore
described.
(3) Third. The use of a mercurial thermometer combined with a pressure
Indicator wherein no vapour of mercury or other vapour is allowed to exist
between, betwixt or intermediate to the mercury in the expansion chamber and
the pressure Indicator all as hereinbefore described.
(4) Fourth. The use of a high range mercurial thermometer combined with a
pressure gauge wherein the liquid or liquids between the pressure gauge & the
expansion chamber can be extended indefinitely as hereinbefore described, more
particularly under Fig. 4.
(5) Fifth.-The use or employment of a vertical column of mercury in high range
thermometers to create an initial pressure on the mercury in any part of the
apparatus to prevent boiling or ebullition of the mercury in or near said part or
parts all as herein before described.
JAMES MURRIE,
Applicant.