An Improvement in Thermometers.
Year: 1890

page_text: Date of Application, 25th Nov., 1890
Complete Specification Left, 25th Aug., 1891-Accepted, 26th Sept., 1891
PROVISIONAL SPECIFICATION.
An Improvement in Thermometers.
I, JOSEPH KENT of 98, Hatton Garden, in the City of London, Clerk, do
hereby declare the nature of this invention to be as follows:-
Clinical and other thermometers, which have the scale marked upon the tube,
are liable to have the markings of the scale defaced or destroyed by the cleaning.
of the instrument with acid, after use in order to prevent infection, and the scale
being on the front of the tube obscures the mercury column and, being at a con-
siderable distance therefrom, the reading of the instrument is neither so legible nor
precise as is desirable.
My invention has for its object to provide such a thermometer with an inde-
structible scale behind and in close proximity to the mercury column whereby to
avoid the objections above mentioned.
To this end, the invention consists in substituting for the enamel, usually
embedded in, and forming an integral part of, the body of the tube at the back of
the bore, à separate scale-marked strip of enamel or other suitable material inserted
into a second bore provided in the tube, the instrument being so far completed
that the said strip may be "pointed" by actual reference to the mercurial column
in the ordinary way of "pointing" the scale-marked tubes, the scale-marked strip
being then inserted in the special bore provided for it and sealed up therein so as
to be fixed accurately in position and effectually protected from injury. The
mercury column being in front of and close to the scale, its height can be accurately
read off with facility.
My invention also relates to the mode of making the double bore tube required
for my improved thermometer, and it consists in blowing two balls on separate
blowing irons, marvering them in the ordinary way, then placing them side by side
and causing them to adhere whilst the glass is soft, and then drawing out the
combined pieces together, to form the double bore tube desired.
The above operations are so conducted that the bore which is to receive the
scale-marked strip will be of considerably greater breadth and sectional area than
the bore for the mercurial column.
Dated this 25th day of November 1890.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.
COMPLETE SPECIFICATION.
An Improvement in Thermometers.
JOSEPH KENT of 98 Hatton Garden, in the City of London, Clerk, 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:-
Thermometers (used for clinical, chemical, and other purposes) which have the
scale marked externally upon the stem or tube, are liable to have the markings of .
the scale defaced or destroyed by the acids to which the instrument is exposed in
use or for cleaning, and the scale being usually on the front of the stem or tube
and at a considerable distance from the mercury column the latter is obscured and
the reading of the instrument is neither so easy nor so precise as is desirable.
3

page_text: My invention has for its object to provide such a thermometer with a scale which
so protected as to be indestructible by acids and which is situated behind the
mercury column whereby the objections above mentioned are avoided.
To this end, the invention consists in inserting a separately-made scale-marked
strip of enamel or other suitable material (such for instance as asbestos paper) into
a second bore formed in the stem or tube às hereafter described, directly in rear
of, and preferably as close as possible to, the bore containing the mercurial
column.
Reference is to be had to the accompanying drawings, forming part of this
Specification, wherein
Figure 1 is a front view of a clinical thermometer constructed according to my
invention.
Figure 2 is a cross-section of the thermometer tube, drawn to a larger scale,
shewing the position of the scale in rear of the mercurial column.
Figure 3 is a cross-section of the united "balls" at the intermediate stage of
manufacture, before being finally
"
"covered and drawn out to form the double
bore tube.
The same letters of reference denote like parts in all the figures.
The thermometer is of the ordinary construction as far as the bulb a and bore b
for the mercurial column are concerned, but it has a second bore c immediately
behind the bore b said bore e being preferably of flattened or oblong form in cross-
section and of considerably greater breadth and sectional area than the bore b so
as to receive a scale-strip d preferably of sufficient width for the graduations
thereon to be perfectly visible at either side of the mercurial column.
The mode of making the double bore stem or tube required for my improved
thermometer, consists in blowing the "ball" for the mercurial tube in the ordinary
way (except that no enamel is applied to it) and on a separate blowing iron
blowing another light ball or cylinder for the scale tube, manipulating the last
mentioned ball to the required shape and causing it to adhere to the first mentioned
"ball
"while both are in a semi-molten state, as shown in Figure 3, which
represents the cross sectional forms and relative dimensions of these "balls" when
they are united and before they are "covered" and drawn, the dotted line roughly
showing the line of junction of the two "balls."
The united "balls" having been allowed to cool to the proper temperature
(which should not be so high that the glass will be soft enough to allow the large
bore c to collapse or become misshapen whilst being covered, nor so low as to cause
the united "balls" to crack off the blowing iron on immersion in the molten
"metal") are subjected to the operation of "covering" by dipping in molten glass
and marvering and are then drawn out together to form a tube with double bore, as
shown in Figure 2, of the ordinary cylindrical or other desired form externally.
A suitable length of such tube is made into a thermometer in the ordinary way by
forming a bulb a in connection with the bore b and otherwise completing the
instrument in the ordinary way, so far as the thermometer proper is concerned, the
end of the bore c nearest the bulb being at same time sealed, whilst its other end is
left open.
The instrument having been so far completed, the strip of enamel or other
material which is to be scale-marked, is then "pointed" by actual reference to
the mercurial column by temporarily affixing it to the front of the stem or tube,
and "pointing" it in the ordinary way of "pointing" the scale-marked tubes (as
shown in Figure 4) the graduations and figures being afterwards marked thereon in
enamel color and fixed by firing in the usual way.
The strip having been divided, marked, and figured, is then inserted in the special
bore c in its proper position with regard to the mercurial column, and is secured
therein by sealing up the end of the bore, the scale being fixed in position therein
either by locally softening the back wall of the scale bore and pinching it in or
compressing it at that point, or by actually sealing the end of the scale-marked
strip into the end of the glass stem at the same time that the scale bore is sealed

page_text: up as above described, so as to fix the strip accurately in position. The strip is
thus effectually protected from injury and the mercury column being in front of,
and close to, the scale, its height can be accurately read off with facility.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what 1
claim is.
1st. The manufacture of a thermometer stem or tube with a second bore of
broad, flattened section formed in it in rear of the bore for the mercurial column,
substantially in the manner and for the purpose specified.
2nd. In a thermometer, the combination with the stem or tube having a second
broad, flattened bore in rear of the mercurial bore, of a separately made scale-
marked strip inserted into said second bore and sealed up therein, substantially as
specified.
Dated this 95th dow of Auœust 1891