Improvements connected with Thermometers for Registering Low Temperatures.
Year: 1893

page_text: Date of Application, 7th Apr., 1893
Complete Specification Left, 8th Jan., 1894-Accepted, 10th Feb., 1894
PROVISIONAL SPECIFICATION.
Improvements connected with Thermometers for Registering Low
Temperatures.
I, ALEXANDER SHIELS, of 190 Bath Street, Glasgow, M.B., C.M., B.Sc., do
hereby declare the nature of this invention to be as follows:-
This invention relates to thermometers for registering low temperatures.
Great difficulty has, heretofore, been experienced in registering accurately, by
means of a thermometer, the low ranges of temperature within refrigerating and like
chambers. This difficulty arises from the fact, that, immediately the thermometer
is taken out of the chamber, it passes into a comparatively warm atmosphere, and
the mercury or other fluid, as a consequence, rises to a certain extent before the
attendant has time for examination. In this manner, the readings usually show
a higher temperature than that which actually exists in the interior of the
chamber.
My invention is designed to minimise this error in the readings, by enclosing the
thermometer within a suitable casing, which is capable of enclosing and retaining
some of the cold air within it, when the thermometer is lifted out of the chamber.
The casing, or a part of it, may be made of a material, or of materials, which are
good non-conductors.
In carrying out my invention, under one arrangement, I fit the thermometer
within a, preferably, glass casing, which is, or may be, surrounded with an outer
metal casing. The metal casing is slotted, so as to allow the thermometer to be
easily seen and the readings taken. The thermometer, at each end, is fitted in
spring bearings, which may be made of rubber, or be spiral or other springs fitted
in a suitable case. The spring bearings allow longitudinal expansion and contraction
of the thermometer tube. The glass casing is, at its lower end, fitted in a brass or
other metal cup, which is, or may be, provided with, or fitted with, an annular brass
ring or projection, which surrounds the bulb of the thermometer.
The glass casing, at its upper end, is provided with a metal or other cap, having
holes in it for the admission of air to the interior of the said casing. The cap has,
or may have, the upper spring bearing for the thermometer fitted to it.
Fitted on top of the cap, is a conical or other shaped lid, which is capable of
sliding on a spindle connected to the cap. The lid is normally held closed on top
of the cap by means of a spring or equivalent, fitted around or to the spindle. The
spindle, and likewise the lid, has a string, wire, or other connection attached
to it.
When the apparatus is lowered into the refrigerating or other chamber, it is held
by the string or other connection, attached to the lid, so that the weight of the
apparatus compresses the spring, and causes said lid to lift off the cap, and allow
cold beavy air to pass into the casing and around the thermometer. The annular
metal projection, connected to the bottom of the casing and surrounding the bulb,

page_text: been pulled up out of the refrigerating chamber, so that, in this manner, sufficient
time is allowed to take an accurate reading.
The construction of the apparatus may be modified in various ways, such as, for
example, by having a small valve or valves at the bottom or other part of the casing,
for the admission of cold air; by having the lid actuated by rods; by having the lid to
slide telescopically on the casing, and to cover and uncover openings, communicating
with the interior of said casing; by having a "hit and miss" grating on top of the
cap, said grating being actuated by means of a spindle; or by having a suitable
valve arrangement on top of the cover, for the admission of cold air.
The apparatus would be equally applicable for registering the temperature of
cold liquids.
Dated this 6th day of April 1822.
H. D. FITZPATRICK,
70, Wellington Street, Glasgow, Agent.
Improvements connected with Thermometers for Registering Low
Temperatures.
I, ALEXANDER SHIELS, of 190 Bath Street Glasgow, M.B. C.M. B.Sc. 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 thermometers for registering low temperatures.
Great difficulty has, heretofore, been experienced in registering accurately, by
means of a thermometer, the low ranges of temperature within refrigerating and
like chambers.
This difficulty arises from the fact, that immediately the thermometer is taken out
of the chamber, it passes into a comparatively warm atmosphere, and the mercury
or fluid as a consequence rises to a certain extent before the attendant has time for
examination. In this manner, the readings usually show a higher temperature than
that which actually exists in the interior of the chamber.
My invention is designed to minimise. this error in the readings, by enclosing the
thermometer within a suitable casing which is capable of enclosing and retaining
some of the cold air within it, when the thermometer is lifted out of the chamber.
The casing, or a part of it, may be made of a material or of materials, which are
good non-conductors.
In carrying out my invention, under one arrangement, I fit the thermometer
within a preferably glass casing, which is, or may be, surrounded with an outer
metal casing. The metal casing is slotted so as to allow the thermometer to be
easily seen and the readings taken. The thermometer at each end, is or may be
fitted in spring bearings, which may be made of rubber, or be spiral or other springs
fitted in a suitable case. The spring bearings allow longitudinal expansion and
contraction of the thermometer tube. The glass casing is at its lower end, fitted in
a brass or metal cup, which is, or may be provided with, or fitted with an annular
brass ring or projection which surrounds the bulb of the thermometer.
The glass casing at its upper end is provided with a metal or other_cap having
holes in it for the admission of air to the interior of the said casing. The cap has
or may have the upper spring bearing for the thermometer fitted to it. Fitted on
the top of the cap is a conical or other shaped lid which is capable of sliding on a
spindle connected to the cap.
The lid is normally held closed on the top of the cap by means of a spring or
equivalent fitted around or to the spindle.

page_text: And in order that my said invention may be properly understood I have nereunto
appended an explanatory sheet of drawings, whereon :-
Fig. 1, is a front elevation of the thermometer.
Fig. 2 is a vertical section of the thermometer.
Fig. 3. is a plan view of the cup c.
Fig. 4, is a section, on the line X-X Fig. 2, looking from below, and
Fig. 5 is a plan view of the cap looking from above, the conical lid f being
removed.
Fig. 6 shows a modified arrangement of the conical lid f.
Referring to the drawings whereon the same reference letters wherever repeated
indicate the same parts
1
a is the thermometer which is surrounded by a brass or other metal casing b
having two slots 61, 62, cut in it. Screwed on to the lower end of the casing is a
brass or other metal cup chaving an upwardly projecting ring on it. Screwed
on to the top of the casing is a cap d having four or other number of holes d' in it.
Screwed into the cap is the spindle e, which is solid at its upper end and hollow at
its lower end. Screwed on to the upper end is the conical lid f. f is a nut screwed
on to the spindle, and f' is an eyelet on the upper end of the spindle. The upper
end of the thermometer tube enters the hollow lower end of the spindle and is held
in place therein by a rubber ring a'. The lower or bulb end of the thermometer
tube is inserted in the ring c' and held in place therein by a rubber cup or a ring c².
A rubber cushion or piston g' is pressed against the upper end of the thermometer
by a spiral spring g.
is the glass tube which is inserted in the metal casing b and held in place
therein by the cap d and cup c.
If desired the conical lid f, may, as shown at Fig. 6, be capable of sliding on the
spindle e and be pressed normally downwards by the spiral spring ; which is held
in proper position, on the spindle, by the nut f'. A wire loop k is attached to eyes l
on the lid f. m, m³, are cords.
With this apparatus, presuming it has a lid f, arranged as at Fig. 6 :-
When it is lowered into the refrigerating or other chamber, it is held by the
cord m attached to the lid f so that the weight of the apparatus compresses the
spring and causes said lid to lift up off the cap d and allow cold heavy air to pass
into the glass tube and around the thermometer. The metal ring c surrounding
the bulb by its conductivity soon reduces the temperature within the casing to the
same as that which prevails within the refrigerating chamber. The thermometer is
pulled up out of the chamber by means of the cord m¹ attached to the spindle e so
that the spiral spring expands and the lid fcloses down on top of the cap d and
locks up the cold air within the casing.
-The-cold-air-locked-within-the-casing and the non-conductivity of the glass tube
and the rubber bearings a', c², prevent the comparatively high temperature of the
surrounding atmosphere affecting the thermometer for some time after it has been
pulled up out of the refrigerating chamber, so that in this manner sufficient time is
allowed to take an accurate reading.
The construction of the apparatus may be modified in various ways, such as, for
example, by having a small valve or valves at the bottom or other part of the
casing for the admission of cold air; by having the lid actuated by rods; by having
the lid to slide telescopically on the casing and to cover and uncover openings
communicating with the interior of said casing by having a hit and miss grating
on the top of the cap, said grating being actuated by means of a spindle or by
having a suitable valve arrangement on top of the cover for the admission of
cold air.
The apparatus would be equally applicable for registering the temperature of
cold liquids.

page_text: 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
consider novel and desire to claim is :-
1. A thermometer for registering low temperatures having a surrounding casing
or its equivalent, so constructed that it is capable of enclosing and retaining some
of the cold air within it when the thermometer is lifted out of the chamber, or
other place substantially and for the advantages as herein before set forth.
2. In thermometers for registering low temperatures the combination with a
casing closed at the lower end and having an inlet at the upper end, of a thermo-
meter fitted therein and held in place by rubber or spring cushions or bearings,
substantially as and for the purpose hereinbefore set forth.
3. The combination with the thermometer a, of the glass tube, and enclosing
metal casing, which is closed at its lower end and has a perforated cap or its
equivalent at its upper end, substantially as hereinbefore described with reference
to the drawings annexed.
4. The general arrangement and combination of parts of the thermometer for
registering low temperatures, substantially as herein before described and shown on
the drawings annexed.
Dated this 6th day of January 1894.
H. D. FITZPATRICK,
70, Wellington Street, Glasgow.