IMPROVEMENTS IN BAROMETERS
Year: 1877

page_text: LETTERS PATENT to Robert Mann Lowne, of East End, Finchley, in the County
of Middlesex, for the Invention of "IMPROVEMENTS IN BAROMETERS."
PROVISIONAL SPECIFICATION left by the said Robert Mann Lowne at the
Office of the Commissioners of Patents on the 9th January 1877.
ROBERT MANN LOWNE, of East End, Finchley, in the County of Middlesex.
"IMPROVEMENTS IN BAROMETERS."
The Invention has for its object improvements in barometers, and relates to
means for rendering them self-compensating for differences of temperatures, and at
the same time providing them with an open and fixed. scale. For this purpose I
employ an instrument having somewhat the character of that class of barometer
known as the Sympiesometer, but instead of allowing the height of the indicating
column of fluid to be varied by any variation of temperature acting upon and
expanding the air in the air bulb or chamber, I construct the barometer with
another bulb or chamber at or near the lower part thereof, the fluid in which is also
affected by changes of temperature. This lower bulb or chamber is filled with
fluid, which rises up the gauge tube, and such fluid is supported by a column of
mercury in a tube open at one end to the outer air, and communicating at the
other with the bottom of the lower bulb or chamber. The scale is fixed between
the two bulbs or chambers.
By this construction of barometer any change of temperature which in the
ordinary construction of Sympiesometer would cause the air in the bulb or chamber
to force down the column of fluid, also acts upon the fluid in the lower bulb or
chamber to expand it, and thereby causes such fluid to force the mercury higher
in the open tube to compensate for the greater pressure of air in the air bulb. I
prefer to use spirit in the lower bulb or chamber.
If it be desired, to prevent rapid changes of temperature from unequally affecting
the contents of the two bulbs or chambers, the air bulb or chamber may be enclosed
in another bulb or chamber surrounding the same, and leaving a space between the
two bulbs or chambers, which space may be filled with spirit or other fluid; or the
entire instrument may be enclosed in a case having a glass face.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Robert Mann Lowne in the Great Seal Patent Office on the. 9th
July 1877.
ROBERT MANN LOWNE, of East End, Finchley, in the County of Middlesex.
"IMPROVEMENTS IN BAROMETERS."
The Invention has for its object improvements in barometers, and relates to
means for rendering them self-compensating for differences of temperature, and at
the same time providing them with an open and fixed scale. For this purpose
I
employ an instrument having somewhat the character of that class of barometer
known as the Sympiesometer, but instead of allowing the height of the indicating
fluid to be varied by any variation of temperature acting upon and expanding
or contracting the air in the air bulb or chamber, I construct the barometer
with another bulb or chamber at or near the lower part thereof, the fluid
in which is also affected by changes of temperature. This lower bulb or chamber
is filled with fluid, which rises up the gauge tube, and such fluid is supported by a
column of mercury or other fluid in a tube open at one end to the outer air, and
communicating at the other with the lower bulb or chamber. The scale is fixed
between the two bulbs or chambers.
By this construction of barometer any change of temperature which. in the
ordinary construction of Sympiesometer would cause the air in the bulb or chamber
to force down the column of fluid, also acts upon the fluid in the lower bulb or
chamber to expand it, and thereby causes such fluid to force the mercury or other
fluid higher in the open tube to compensate for the greater pressure of air in the
air bulb.
If it be desired, to prevent differences and rapid changes of temperature from
unequally affecting the contents of the two bulbs or chambers, the air bulb or
chamber may be enclosed in another bulb or chamber surrounding the same, and
leaving a space between the two bulbs or chambers, which space may be filled with
spirit or other fluid; or the entire instrument may be enclosed in a case having a
glass face, but the arrangement I prefer for this purpose is that shown at Figures 3
and 4.
And in order that my 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 front elevation of a small-size barometer constructed
according to my Invention, and Figure 2 is a section through the bulbs and tubes of
the same; and Figure 3 represents a front elevation to a reduced scale of a large
long-range barometer constructed according to my Invention, but representing a
modification in the form and position of the parts; and Figure 4 represents a
sectional elevation drawn to a larger scale of parts of the barometer shown at
Figure 3.
In the various Figures like parts are marked with similar letters of reference.
a is the gauge tube, which is connected at its upper end with an air bulb or
chamber b, and at its lower end with a bulb or chamber c to contain any suitable
fluid, and d is a tube, which is connected to the chamber c, and whose upper end is
open to the atmosphere.
In the barometer shown at Figures 1 and 2 the bulb or chamber c is filled with
oil or other fluid, which rises up the gauge tube a, and the tube d is filled up to
the point with mercury, which also rises up to the bulb or chamber c.
The barometer shown at Figures 3 and 4 instead of having the air bulb or
chamber 6 fixed at the upper part of the gauge tube a, as in the arrangement shown
at Figures 1 and 2, has the air bulb or chamber b and the fluid bulb or chamber c

page_text: placed side by side, and immersed in a cistern e in order to keep the air chamber b
and the fluid chamber c at an equal temperature, and thereby prevent differences
and rapid changes of temperature from affecting unequally the contents of the two
bulbs or chambers b, c. The gauge tube a is connected by a small tube a¹ with the
air bulb or chamber b. In this arrangement the fluid chamber c is filled with oil
or other fluid, and the same fluid rises up both the gauge tube a and the tube d.
Having thus described the nature of my said Invention and the mode in which I
carry the same into effect, I would have it understood that what I claim is, con-
structing barometers of the character described with a fluid bulb or chamber, in
addition to the ordinary air bulb or chamber, in manner and for the purpose sub-
stantially as herein shown and described.
.
In witness whereof, I, the said Robert Mann Lowne, have hereunto set my
hand and seal, this Fifth day of July, in the year of our Lord One thousand
eight hundred and seventy-seven.
R. M. LOWNE. (L.S.)