Improvements in Clinical Thermometers.
Year: 1898

page_text: Date of Application, 19th Apr., 1898
Complete Specification Left, 6th July, 1898-Accepted, 6th Aug., 1898.
PROVISIONAL SPECIFICATION.
Improvements in Clinical Thermometers.
I, GEORGE BRITTAIN, of 10, Clerkenwell Road, in the County of Middlesex,
Scientific Instrument Maker, do hereby declare the nature of this invention
to be as follows:
more
at
The invention relates to improvements in clinical thermometers.
Clinical thermometers as is well known are set for use by shaking the mercury
back through the contraction of the tube and this operation with
thermometers is
or less difficult
comparatively large bore
task, but with modern thermometers which are now commonly made with
a small bulb and a very fine bore in order to obtain a quick registration
of the temperature this difficulty is very much increased owing to the capillary
action of the fine bore of the tube.
Now the object of the present invention is to construct a quick registering
thermometer in such manner that the difficulty above pointed out will be removed
or modified.
In carrying the invention into effect the thermometer is formed with a small
bulb and fine bore as is now customary, but between the contraction and the scale
the bore is provided with a small chamber which is filled with mercury.
The effect of this device is that upon shaking the thermometer to set the same for
use the body of mercury within the chamber will act to draw the mercury in the
bore into the chamber and force some of it through the contraction.
By these means the thermometer may be reset for use with very little effort,
whilst at the same time the sensitiveness and accuracy of the thermometer are not
impaired.
11
1011
SA 1000
I, GEORGE BRITTAIN, of 10, Clerkenwell Road, in the County of Middlesex,
Scientific Instrument Maker, 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:-
The invention relates to improvements in clinical thermometers.
Clinical thermometers as is well known are set for use by shaking the mercury
back
the
through the contraction of
tube and this operation with

page_text: .
comparatively large bore thermometers is a more or less difficult
task, but with modern thermometers which are now commonly made with
a small bulb and a very fine bore in order to obtain a quick registration
of the temperature this difficulty is very much increased owing to the capillary
action of the fine bore of the tube.
Now the object of the present invention is to construct a quick registering
thermometer in such manner that the difficulty above pointed out will be removed
or modified.
In carrying the invention into effect the thermometer is formed with a small
bulb and fine bore as is now customary, but between the contraction and the scale
the bore is provided with a chamber which is filled with mercury.
The effect of this device is that upon shaking the thermometer to reset the same
for use the body of mercury within the chamber will act to force some of the
mercury in the chamber down through the contraction and at the same time draw
some of the mercury in the bore down into the chamber.
And in order that the said invention may be more clearly understood and
readily carried into effect I will proceed aided by the accompanying drawings more
fully to describe the same.
DESCRIPTION OF THE DRAWINGS.
Figure 1 represents a face view of a complete thermometer constructed
according to the present invention,
Figure 2 is a similar view representing an incomplete thermometer and
Figure 3 represents a portion of Figure 2.
The several figures in which like parts are indicated by similar letters of re-
ference are drawn to an enlarged scale for the sake of clearness whilst Figures 1
and 3 are drawn to an increased scale with respect to Figure 2.
Referring to Figure 1 a represents the body of the thermometer, a¹ represents
the usual small bulb common to quick registering thermometers, a² represents the
bore which is also of the customary minute character and a represents the usual
contraction above the bulb.
According to the present invention at a point between the scale and the con-
traction a the bore a² is formed with a swelling or enlargement constituting a
chamber a and the bore a2 and chamber a are filled with mercury to a point
slightly above the chamber a as represented in the drawings and thus a body of
mercury is always contained within the chamber.at.
The action of this device may be described as follows:-
:-
In order to reset the thermometer for use after the temperature of a patient
has been taken and the mercury has been allowed to cool the instrument is shaken
in the usual way when the body of mercury within the chamber a will by its
weight act to force some of the mercury in the chamber down through the con-
traction a³ and at the same time draw some of the mercury remaining in the upper
part of the bore a² down into the chamber a².
By these means the thermometer may be reset for use with very little effort and
the usual objection to quick registering thermometers will be removed whilst at
the same time the sensitiveness and accuracy of the thermometer remain un-
impaired.
Referring to Figures 2 and 3 a convenient way of producing a thermometer of
the character herein before described is the following:
represents the usual overflow chamber provided for the purpose of regulating
the quantity of mercury contained in the thermometer and a represents the bottom
chamber to which the bulb is connected as is well understood.
The chamber at is produced after the contraction chamber a³ and previous
to filling the thermometer with mercury by heating the tube at the point where
the chamber a is required and also at the bottom chamber the effect being to
expand the air and distend the bore at the point at after which the end of the tube
is unsealed and mercury is introduced thereinto in the well known manner.

page_text: The following has in practice been found a convenient way of regulating the
quantity of mercury contained in the thermometer.
The bulb is first heated by the hand of the workman and some of the mercury
is thus caused to rise into the overflow chamber a5.
It is now necessary to pass into the overflow chamber as the slight excess of
mercury that still remains in the bore and for this purpose and in order to prevent
too large a quantity passing from the chamber a to the chamber a³ the tube is
heated at a point just below the overflow chamber a³ and a kind of contraction a' is
formed by drawing out the tube and attenuating the bore a³.
The thermometer is now heated to 112° Fahrenheit which has the effect of
causing the excess of mercury to force its way through the contraction a' into the
overflow chamber a and the flame is then suddenly applied to the part a and the
mercury is thus separated at that point which operation is facilitated by said con-
traction which contraction also prevents the mercury in the chamber at being
drawn up into the chamber a5.
If too much mercury passes into the overflow chamber a it is shaken back and
when the exact quantity is arrived at the overflow chamber a5 with the contained
mercury is removed by the aid of the flame and the thermometer is finished in the
usual way.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is:-
A clinical thermometer formed with a mercury chamber consisting of a swelling
or enlargement of the ordinary bore above the contraction substantially as herein
shown and described and for the purpose stated.
Dated this 6th day of July 1898.
WHITE & WOODINGTON,
Rooms 221-225, Birkbeck Bank Chambers,
Southampton Buildings, London, Agents.