Improvements in Maximum Thermometers.
Year: 1898

page_text: KRUVIDIONAL DIECIFICATION.
Improvements in Maximum Thermometers.
I, GEORGE WILLIAM SIMPSON, Meteorological Instrument Manufacturer, of 19,
Cross Street, Hatton Garden, in the County of London, do hereby declare the nature
of this invention to be as follows:-
In maximum thermometers as now made such as so-called clinicals" having
very fine bores, a difficulty is experienced in adjusting the indicating column of
mercury, considerable violence having to be used to shake the column of mercury
or indicating fluid below the indicating marks upon the tubes. To obviate this
difficulty and the danger attending this method of adjustment, I construct thermo-
meters with the usual constriction, but instead of finishing the tube at the top
in the usual manner, I make an enlargement of the bore to form a chamber to
contain air, gas or mercury, or any other material or liquid suitable for the
purpose.
In one form of my invention I place a pad or elastic diaphragm either upon
the outside or inside of the enlargement or chamber before-mentioned, at the
upper part of the tube, in such a manner that the pad or diaphragm when pressed
will force the contents in the space between the surface of the indicating fluid
and pad with sufficient force to drive the indicating medium down below the
indicating marks upon the tube.
This pad is so constructed that it returns to its normal position directly the
pressure is taken off.
The thermometer is so constructed that the indicating column can be left in
any position in the tube.
To avoid the indicating fluid being forced below or right through the constriction,
I place a cap as a protection to the top of the tube to enable me to fit a push,
screw, or spring, so adjusted that when pressed upon or turned, it will give suf-
ficient movement to the indicating column to adjust it below the marks upon
the outside, or at the point required, but will not force the whole of the column
through the constriction at the lower end of the tube.
The cap may be so made as to form the upper part or lid of the protecting case
usually used for clinical thermometers when not in use.
By this manufacture the position of the thermometer does not in any way inter-
fere with the correct action or indication of the indicating column and can be
readjusted in any position.
The thermometers can be made where necessary with the upper portion so
constructed that the indicating column can be adjusted by heat either applied
direct or caused by friction or otherwise; in this construction heat applied to
a closed chamber containing air formed at the top of the tube, causes the contained
air to be expanded and to press upon the column of mercury and the same is
thereby adjusted by the increased pressure.
A great advantage of my invention is the simplicity and certainty of its action,
a simple pressure of the finger adjusting the column of mercury, no skill or pre-
Pi Q77

page_text: vious knowledge being required; the impossibility of getting the thermometer
out of order by any fair means; the absence of all violence in shaking or swinging
to adjust the indicating column; the advantage of knowing that the thermometer
is properly re-adjusted before again using it even in a dark room and without
requiring to be looked at.
My improvements can be applied to almost any form of maximum thermometers
either lens or round or any other shape.
Dated this 5th day of July, 1908
Improvements in Maximum Thermometers.
I, GEORGE WILLIAM SIMPSON, Meteorological Instrument Manufacturer, of 19,
Cross Street, Hatton Garden, in the County of London, do hereby declare the nature
of this invention and in what manner the same is to be performed to be. particu-
larly described and ascertained in and by the following statement: --
Considerable inconvenience and difficulty is commonly experienced, in adjust-
ing the, indicating column of mercury or indicating fluid, in maximum thermo-
meters, and particularly in clinical thermometers having very fine bores."
Such adjustment is commonly effected by violently shaking the thermometer,
in order to cause the indicating column of mercury or fluid to descend below the
index or scale upon the tube; now the object of my invention is to provide means
whereby the indicating column can be acted upon, and the adjustment effected,
without loss of time and with greater certainty than heretofore.
With this object in view I construct the tube with an air or gas chamber at
the upper part thereof above the indicating column, and communicating with the
bore, and I provide means whereby the air or gas pressure in the chamber and
consequently in the bore of the tube above the indicating column, can be increased
when it is desired to adjust the indicating column, such increase of pressure acting
directly to force the column to its required normal position.
I will describe my invention with reference to the accompanying drawings
whereon Fig. 1 shews my improved clinical thermometer in vertical section, and
provided with an elastic diaphragm and plunger, for increasing the air or gas
pressure in the chamber aforesaid. Fig. 2 is a similar view of the upper part of
a thermometer fitted with a screw acting plunger. Fig. 3 is an enlarged view
of the upper end of one of my thermometers, where the diaphragm is directly
acted upon by the finger of the user. Fig. 4 is a view of the upper end of a thermo-
meter where the chamber is closed and the contained air or gas, (hereinafter
termed air), is increased in pressure when required, by heat applied to the closed
chamber, and Fig. 5 is a sectional view of a clinical thermometer, similar to that
shewn at Fig. 1, but shewing same enclosed in a tubular protecting case.
According to my invention I preferably form the tube A with the usual con-
striction B common in fine bore maximum themometers, and referring more particu-
larly to Fig. 1, I form an open cup-shaped chamber C at the upper end of the
tube A, and communicating with the bore of the said tube. The open end of the
cup-shaped chamber C, I close by means of an elastic diaphragm D, say for example
of india rubber, held in place by a metal cap or ferrule DI, and the chamber C
and the bore of the tube above the indicating column E, then contains air, or
in some cases it may contain gas.
Mechanical pressure is applied upon the exterior surface of the diaphragm D,

page_text: to increase the pressure of the air between the said diaphragm and the top of the
indicating column, for the adjustment of the latter, and at Fig. 1 such pressure
is applied by means of a plunger F, guided, and capable of sliding, in a casing G
fitted over the metal ferrule D'. The plunger F is held up by a spring F¹ and
is provided with a pressure knob or equivalent F2, by which the plunger can be
depressed a pre-determined distance, when it is desired to force the indicating
column below the index.
Obviously the plunger F may be screw threaded as at Fig. 2, and be revolved
in order to depress the diaphragm D, or the plunger may be dispensed with and
the diaphragm D as at Fig. 3 made preferably with a convex surface to be depressed
by the finger of the user.
At Fig. 4 the chamber C is shewn entirely closed, and when it is required
that the indicating column be returned to its normal position, the closed chamber C
is heated, by say the hand of the user or by friction, the enclosed air thereby
expanded, and the indicating column forced down as required.
At Fig. 5 a construction of thermometer as at Fig. 1 is illustrated fitted with
an ordinary metal tubular case H which takes over the lower part of the end
casing G.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is:-
1. In maximum thermometers wherein the registering column of indicating
fluid, after recording the maximum temperature, remains stationary within the
bore until forcibly returned by the user; an air chamber located above the indi-
cating column, the air chamber communicating with the bore, and means for
increasing the pressure of air in the air chamber and bore above the indicating
column, whereby the said indicating column is returned to its normal position
substantially as set forth.
2. In maximum thermometers wherein the registering column of indicating
fluid, after recording the maximum temperature, remains stationary in the bore
until forcibly returned by the user; the combination of a cup-shaped chamber
at the end of the tube, the chamber communicating with the bore above the
registering column, and an elastic diaphragm closing the top of the chamber,
whereby upon pressure being applied to the diaphragm and the contained air
compressed, the indicating fluid is thereby forcibly returned to its normal
position, substantially as set forth.
3. In maximum thermometers wherein the registering column of indicating
fluid, after recording the maximum temperature, remains stationary in the bore
until forcibly returned by the user; the combination with a cup shaped chamber
at the end of the tube, the chamber communicating with the bore above the
registering column, and an elastic diaphragm closing the top of the chamber,
of a plunger, located above the diaphragm, to depress the latter when required,
and means for guiding the plunger and regulating the distance of its travel,
whereby upon the plunger being slidden by the user, the diaphragm is acted upon
to the required extent, the air compressed, and the indicating column thereby
forcibly returned to its normal position, substantially as set forth.
4. In maximum thermometers wherein the registering column of indicating
fluid, after recording the maximum temperature, remains stationary in the bore
until forcibly returned by the user; a closed chamber located at the end of the tube
and communicating with the bore above the registering column the chamber and
the bore above the said registering column containing heat expansible medium,
whereby upon heat being applied by friction or otherwise to the exterior of the
said chamber, the expansible medium therein is expanded and the indicating
column forcibly returned to its normal position, substantially as set forth.
5. The special arrangements and constructions of maximum thermometers
having an air chamber above the indicating column and communicating with the

page_text: bore and means for increasing the pressure of air in the air chamber and bore in
order to return the indicating column to its normal position, all combined and
acting substantially as and for the purposes described with reference to the accom-
panying drawings.”
ננת
11.
0 1
1000
BREWER & SON,
London and Leeds, Agents for the Applicant.