Improvements in Clinical Thermometers.
Year: 1897

page_text: Improvements in Clinical Thermometers.
I, FRANK COSSOR, of 15, Clerkenwell Green, in the County of London, Meteoro-
logical Glass Blower, do hereby declare the nature of this invention to be as
follows:
The invention has for its object improvements in clinical thermometers whereby
whilst the indestructible index is obtained as heretofore, such index can be readily
shaken down below the scale with the application of very slight force.
For this purpose I form between the bulb and the clinical bore, a bore some-
what larger than that of the clinical bore or I form a somewhat large cavity or
cavities between the bulb and the clinical bore so that the enlarged bore or the
cavity or cavities may contain a comparatively considerable weight of mercury
and I form the constriction for the indestructible index between such enlarged
bore or cavity or cavities and the bulb. The scale will evidently be applied only
to that part of the stem containing the clinical bore.
When in use the mercury has risen to the temperature of a patient and the
indestructible index has been formed by means of the constriction, the instru-
ment requires only a very slight swing to cause the return of the index below the
scale, the comparatively considerable weight of mercury within the enlarged bore or
within the cavity or cavities assisting and ensuring the passage of mercury past
the constriction into the bulb.
100%
Improvements in Clinical Thermometers.
I, FRANK COSSOR, of 15, Clerkenwell Green, in the County of London, Meteoro-
logical Glass Blower, 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 has for its object improvements in clinical thermometers whereby
whilst the indestructible index is obtained as now usual the column of mercury
in the indicator tube can be readily shaken down below the scale with the appli-
cation of very slight force.
For this purpose I form between the bulb and the indicator tube, a bore some-
what larger than that of the indicator tube or I form a somewhat large cavity or

page_text: cavities between the bulb and the indicator tube so that the enlarged bore or the
cavity or cavities may contain a comparatively considerable weight of mercury
and I form the constriction for the indestructible index between such enlarged
bore or cavity or cavities and the bulb.
The drawing annexed shows on an enlarged scale a longitudinal section of a
clinical thermometer constructed in the manner I prefer for carrying out my
invention.
A is a piece of ordinary glass tube with a fine bore such as used in ordinary
clinical thermometers. B is a length of flint glass tube of larger bore (preferably
a flattened bore) joined at one end to the end of A.
C is a bulb containing mercury joined to the other end of B.
D is a short sudden constriction formed in the bore of the tube B near to the
bulb and adapted as now usual in registering thermometers for restraining all
mercury which is forced past it when the bulb is heated from passing back to
the bulb when the bulb cools down.
The object of forming the length of tube B with a flattened bore is to allow of
the constriction 1) being more readily formed than in the ordinary clinical ther-
mometer.
When a clinical thermometer formed in the above way is used mercury flows
from the bulb past the constriction and into the indicator tube in one unbroken
column as the bulb becomes heated and when the mercury has risen to the tem-
perature of a patient and the indestructible index has been formed by means of
the constriction the instrument when it has been allowed to cool requires only a
very slight swing to cause the return of the column of mercury from the indi-
cator tube the momentum imparted by the slight swing to the comparatively
large body of mercury within the enlarged portion of the bore or within the
cavity or cavities causing a large flow of mercury past the constriction and into
the bulls and thereby allowing the column of mercury to pass back freely from
the indicator tube.
I would state that I am aware that in that class of thermometers in which the
column of mercury after rising from the bulb when the bulb is heated is always
free to pass back to the bulb on the bulb being cooled, and in which a small por-
tion of the column of mercury is separated from the remaining portion by a small
air speck which short or index length of the column of mercury is left behind
in the indicator tube when the bulb cools and remains indicating the temperature
to which the thermometer was heated, it has before been proposed to form an
enlargement of the bore near to the bulb so that the short or index length of the
column of mercury when shaken down into this enlarged portion of the bore
may be retained therein and hindered from joining the main body of mercury in
the bulb, and also that it has been proposed to form a contraction between the
bulb and the enlarged portion of the bore to assist in retaining this short or index
length of mercury from entering the bulb.
I am also aware that ordinary clinical thermometers when they have been badly
made so that the column of mercury rises too high in the tube for allowing of
the required range of temperature being registered an extremely small enlarge-
ment of the bore has been made near to the constriction of the bore so as to reduce
the height to which the columm of mercury rises in the tube for any given tem-
perature but such small enlargement would practically have no effect in enabling
the column of mercury to be more readily shaken back from the tube and would
not effect the object of my invention.
Having now particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed I declare that what
I ciaim is:-
:-
1. A clinical thermometer having between the bulb and the fine bore of the
indicator tube, a length of tube of larger bore having in it a sharp sudden con-

page_text: striction adapted to break the column of mercury when the bulb cools and stop all
mercury from passing back from the indicator tube to the bulb.
2. A clinical thermometer having between the sharp constriction and the fine
bore of the indicator tube a cavity or cavities capable of containing a compara-
tively large body of mercury so that when the thermometer has been used and
this cavity has become filled with mercury and the mercury has risen in the indi-
cator tube, a slight swing or jerk will after the thermometer has been allowed
to cool impart sufficient momentum to the mercury in the cavity to cause a large
flow of mercury past the constriction and into the bulb and thereby allow the
column of mercury to pass back freely from the indicator tube.
3. A clinical thermometer constructed substantially as hereinbefore described
and illustrated in the drawing annexed.