IMPROVEMENTS IN THERMOMETERS
Year: 1878

page_text: LETTERS PATENT to William David Bowkett, of Leeds, in the County of York,
Surgeon, for the Invention of "IMPROVEMENTS IN THERMOMETERS."
T
1018
1
theth June 1970
PROVISIONAL SPECIFICATION left by the said William David Bowkett at
the Office of the Commissioners of Patents on the 6th June 1878.
WILLIAM DAVID BOWKETT, of Leeds, in the County of York, Surgeon. "IM-
PROVEMENTS IN THERMOMETERS."
The object of this Invention is to produce instruments for the continuous regis-
tration of varying temperatures. These instruments are more particularly intended
to be used for clinical purposes, but they may also be used for other purposes when
it is desirable to have an indication and record of the variations that have taken
place in temperature during a given space of time.
The form or construction of apparatus admits of variation, according to the nature
of the purpose for which the instrument is intended to be used, but all the instru-
ments will be constructed on the same principle.
To
A convenient form of instrument for clinical purposes may be described as con-
sisting of a close vessel filled with any fluid or liquid which is expansible by
variations of temperature, such, for instance, as alcohol, mercury, air, or gases.
this close vessel is adapted a more or less bent tube, the interior of which commu-
nicates at one of its ends with the interior of the close vessel, so that the capacities
of both these parts are filled with the expansible liquid or fluid. The outer end of
the bent or curved tube is connected in any convenient manner with a mechanical
arrangement consisting of a lever or levers mounted on a fixed point or centre, so
that as the expansible liquid or fluid in the closed vessel or curved tube expands or
Daina B77

page_text: contracts by the variations in temperature, the tendency of the bent tube will be to
either straighten out or become more curved, and this motion of the tube will be
communicated to the lever which is connected therewith, and which will therefore
be made to move on its centre or fulcrum.
In order to register these movements of the lever a pencil or tracing point is
adapted to the moving end thereof, and is made to bear against the face of a dial or
cylinder to which an uniform slow rotary motion is imparted by clockwork, so that
as the dial or cylinder rotates, a line corresponding to the motions of the lever (and
consequently to the variations of temperature to which the instrument is exposed)
will be distinctly marked thereon, and may afterwards be referred to. The face of
the dial or cylinder must be graduated or divided into degrees corresponding to the
degrees of temperature.
As a modification of this apparatus, the close vessel may for some purposes be
dispensed with, and a flat tube bent into the form of a convolute may be employed.
One end of this tube may be fixed, and the other connected to the lever which
carries the pencil or pointer, whereby the motions of the tube and lever are marked
on the rotating dial or cylinder; or, if preferred, the pencil or pointer may be
adapted direct to the end of the convolute tube.
As another modification, the bent tube may be dispensed with, and the close
vessel made with a corrugated expansible side, which, as the expansible liquid or
fluid in the vessel is acted on by the variations in temperarure to which it may be
exposed, will act on the expanding side, and the motions of this latter will be com-
municated by levers or suitable gearing to the registering pencil or point, which will
mark the variations on a dial or cylinder, as in the other instances.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by the
said William David Bowkett in the Great Seal Patent Office on the 6th
December 1878.
WILLIAM DAVID BOWKETT, of Leeds, in the County of York, Surgeon.
PROVEMENTS IN THERMOMETERS."
"IM-
The object of this Invention is to produce instruments for the continuous regis-
tration of varying temperatures. These instruments are more particularly intended
to be used for clinical purposes, but they may also be employed under other circum-
stances for obtaining a record of the variations that have taken place in temperature
during a given space of time.
The form or construction of the apparatus admits of variation, according to the
nature of the purpose for which the instrument is intended to be used, but all the
instruments will be constructed on the same principle.
A convenient form of instrument for clinical purposes is shewn in Sheet I. of the
accompanying Drawings, Fig. 1 being a plan view, and Fig. 2 a longitudinal sectional
elevation of the instrument. In these Figures A is a closed vessel, in the centre of
which is an opening for the reception of a watch movement fitted with a rotating
dial B in place of hour and minute hands. C is a bent tube or open-ended
ring, one end of which is fixed to and in communication with the vessel A, the other
end being closed and free to move under the varying effects of temperature upon the
tube; this free end of the tube C is jointed to a radius arm D, which is capable of
rocking on its fulcrum d, and is fitted at its opposite end with a style or
marker d¹.
In Fig. 1 the apparatus is shewn as in its normal or quiescent state, the style
or marker d¹ being in coincidence with the centre of the dial B. The central part
of this dial is graduated with concentric circles b, which may represent degrees of
temperature varying from, say, sixty to one hundred and twenty-degrees Fahr., and
it is the variations between these degrees in the temperature of the patient within a
given time, say, twelve hours, that the instrument is intended to record by means
of the style or marker d¹.
The vessel A is filled with some suitable fluid which will expand with heat, and
such fluid enters also into and fills the tube C; as therefore the fluid expands or
contracts, the free end of the tube C will recede from or approach the fixed end of
the tube, and thereby move this arm D, and cause its style or marker to travel more
or less over the dial B. The graduated central portion of this dial is coated with a
film of paint or other suitable composition to receive the scratchings of the style or
pointer as it travels over over the dial.
In using this instrument the clock work is set in action, and the instrument being
applied to the body of the patient, the confined fluid will as it becomes heated
expand, and thereby cause the tube C to actuate the radius arm D, and the style or
pointer at the free end of the arm will now scratch through the composition and
thereby trace the variations in temperature to which the instrument has been sub-
jected from hour to hour of its use.
Fig. 3 shews an imaginary course which the style or marker has taken during six
hours, the pointer having started from the normal position shewn at Fig. 1. This
illustration will sufficiently indicate the action of the instrument, whatever form it
may be found desirable to give it to suit the various applications of which it is
Busceptable.
In some cases, instead of painting over the face of the dial, a graduated paper or
card may be applied thereto to receive the markings of a pencil fitted to the radius
arm, as shown at Fig. 4.
The expanding fluid supplied to the instrument may consist of alcohol, mercury,
air, or gas, but the first-mentioned fluid is in general to be preferred.

page_text: A modification of this clinical instrument is shewn in plan view at Fig. 5, Sheet II.
In this arrangement the tube C is fixed to and in communication with the case A
at about the middle of its length, and the two ends of the tube are thus left free.
To one end the radius arm or marker is connected as before, but the fulcrum of the
radius arm is carried by a link c, which is pivotted to the opposite extremity C. By
this arrangement the amount of motion of the pointer is increased, owing to the two
ends of the tube acting in opposite directions upon the pivotted radius arm. In this
as in all cases the graduations indicating temperatures must be made to correspond
to the amount of motion of the style or pointer due to the variations of temperature
upon the confined fluid.
'
Fig. 6, Sheet I., shews the instrument modified to indicate the temperature of an
apartment. The clock with its dial B is mounted on a stand E, and the dial is
graduated as already explained. C₁ is the expanding tube, which is made of suffi-
cient capacity to contain the expansible fluid without the use of a case A, as in the
other examples. This tube is supported at the middle of its length on the framing
E, and pivotted to the opposite ends of the tube are the radius arm D, fitted to
receive a pencil, and a link rod C₁, which is jointed to the radius arm; thus the
motions of the style or marker will be due, as in the last-described arrangement, to
the compound action of the opposite ends of the tube C.
Fig. 7, Sheet II., represents a slight modification of the arrangement illustrated at
Fig. 6. In this instance the expanding tube C is hidden within the clock case, and
its position is for this purpose inverted. The radius arm terminates in a style or
marker instead of carrying a pencil, and it is pivotted to one end of the tube C, and
connected by a link to the other end of that tube.
Having now set forth the nature of my Invention of "Improvements in Ther-
moneters," and explained the manner of carrying the same into effect, I wish it to
be understood that under the above in part recited Letters Patent I claim, in com-
bination with a marker so arranged as to be actuated by changes of temperature, a
rotating or travelling surface graduated for periods of time, and actuated by clock-
work, as and for the purpose above set forth.
In witness whereof, I, the said William David Bowkett, have hereunto set
my hand and seal, this Fourth day of December, in the year of our Lord
One thousand eight hundred and seventy-eight.