IMPROVEMENTS IN THERMOMETRY AND IN APPARATUS USED THEREFOR
Year: 1884

page_text: I, GEORGE THOMAS BEILBY of Midcalder, in the County of Midlothian, North
Britain, Fellow of the Chemical Society and Chemical Engineer do heroby
declare the nature of the said invention for "IMPROVEMENTS IN THERMOMETRY
AND IN APPARATUS USED THEREFOR" to be as follows:―
::
This invention consists of certain improvements in the system of Thermometry
and apparatus used therefor described in the Provisional Specification of the said
George Thomas Beilby No 3750 A.D. 1884. Under the system there described the
pressure of the gas or air within the instrument is regulated by a special form of
apparatus or is allowed to vary with the atmospheric pressure. By my present
invention an approximately constant pressure is maintained within the instrument
when at work by continuing the free end of the measuring tube into a vessel of
comparatively large capacity. This additional vessel, which for the sake of
distinction I call the "pressure vessel," is closed to the outer air; it is, like the
measuring tube, surrounded with a steam jacket by which a constant temperature
is maintained. When the ratio of the capacities of the measuring tube and
pressure vessel" is known, the appropriate correction for the slightly varying.
pressure within the instrument is easily applied to the graduation.
"
By the employment of the "pressure vessel" the instrument becomes a close
thermometer, which having been once filled with dry air or gas is not liable to
derangement from tarnishing of the inside of the tubes or of the mercury.

page_text: I, GEORGE THOMAS BEILBY, of Midcalder, in the County of Midlothian, North
Britain, Fellow of the Chemical Society and Chemical Engineer do hereby declare
the nature of the said invention for IMPROVEMENTS IN THERMOMETRY AND IN
APPARATUS USED THEREFOR and in what manner the same is to be performed, to
be particularly described and ascertained in and by the following statement:―
My Invention consists of certain improvements in the system of Thermometry
and apparatus used therefor described in the Complete Specification of the said
George Thomas Beilby N° 3750 A.D. 1884. Under the system there described the
pressure of the gas or air within the instrument is regulated by a special form of
apparatus or is allowed to vary with the atmospheric pressure. By my present
Invention an approximately constant pressure is maintained within the instrument
when at work by continuing the free end of the measuring tube into a vessel of
comparatively large capacity. This additional vessel, which, for the sake of
distinction I call the "pressure vessel" is closed to the outer air, it is, like the
measuring tube, surrounded with a steam jacket by which a constant temperature
is maintained. When the ratio of the capacities of the measuring tube and
'pressure vessel" is known, the appropriate correction for the slightly varying
pressure within the instrument is easily applied to the graduation.
"
By the employment of the "pressure vessel," the instrument becomes a close
thermometer, which having been once filled with dry air or gas is not liable to
derangement from tarnishing of the inside of the tubes or of the mercury.
In order that my said Invention may be most fully understood and readily
carried into effect, I will proceed to describe the Drawings hereunto annexed.
Figure 1, is a vertical section of one form of the improved thermometer
constructed according to this Invention, and
"
Figure 2, is a vertical section of the same instrument with a different shape of
pressure vessel."
By the Instrument represented at Figure 1, an approximately constant pressure
is maintained within the instrument when at work by continuing the free end of
the measuring tube a, into the pressure vessel b, of comparatively large capacity.
This pressure vessel b, is closed to the outer air; it is, like the measuring tube a,
surrounded with the steam jacket c, and casing d, by means of which a constant
temperature is maintained in the measuring tube a, and chamber b, when steam is
caused to flow into and out of the said jacket c, by connecting it with a steam
boiler through a pipe attached to one of the connections e, or f.-The bulb g, and
capillary tube h, both of the instrument now described as well as of that shewn
at Figure 2, of the annexed drawings are identical with those described in my
aforesaid Specification and therefore need not be here further referred to. When the
ratio of the capacities of the measuring tube a, and pressure vessel b, is known, the
appropriate correction for the slightly varying pressure within the instrument is
easily applied to the graduation.
The instrument represented at Figure 2, is one wherein the pressure vessel or
regulator takes the form of a tube i, situated parallel with the measuring tube a,
with which it is connected at its upper end at j, as shewn and (as in the instrument
represented at Figure 1,) is surrounded with the steam jacket c, and casing d, by
means of which a constant temperature is maintained.

page_text: Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed, I declare that what
I claim is :-
The improved Thermometer wherein the pressure vessel b, in Figure 1, and h, in
Figuro 2, is combined with the measuring tube a, surrounded with a casing for
maintaining a constant temperature in the measuring tube and pressure vessel,
substantially as and for the purposes hereinbefore described.
Dated this Sixth day of January 1885
J. H. JOHNSON, DAY & JOHNSON,
Applicant's Agents.