AN IMPROVEMENT IN GAUGE GLASSES OR TUBES FOR THE WATER GAUGES OF STEAM BOILERS AND. FOR OTHER LIQUID GAUGES, APPLICABLE ALSO TO CERTAIN OTHER INSTRUMENTS IN WHICH THE HEIGHT, LENGTH OR POSITION OF A LIQUID COLUMN IS TO BE ASCERTAINED
Year: 1883

page_text: LETTERS PATENT to Alexander Melville Clark of the firm of A M and
W Clark of 53 Chancery Lane in the County of Middlesex, Fellow of the
Institute of Patent Agents for an Invention of AN IMPROVEMENT IN GAUGE
GLASSES OR TUBES FOR THE WATER GAUGES OF STEAM BOILERS AND. FOR
OTHER LIQUID GAUGES, APPLICABLE ALSO TO CERTAIN OTHER INSTRUMENTS
IN WHICH THE HEIGHT, LENGTH OR POSITION OF A LIQUID COLUMN IS TO BE
ASCERTAINED communicated to him from abroad by Auguste Guilbert-Martin,
of Saint Denis près Paris, France, Chemist
"
PROVISIONAL SPECIFICATION left by the said Alexander Melville Olark at
the Office of the Commissioners of Patents on the 17th October 1883.
ALEXANDER MELVILLE CLARK of the firm of A. M. and W. Clark of 53 Chancery
Lane in the County of Middlesex Fellow of the Institute of Patent Agents,
AN IMPROVEMENT IN GAUGE GLASSES OR TUBES FOR THE WATER GAUGES OF
STEAM BOILERS AND FOR OTHER LIQUID GAUGES APPLICABLE ALSO TO CERTAIN
OTHER INSTRUMENTS IN WHICH THE HEIGHT, LENGTH, OR POSITION OF A LIQUID
COLUMN IS TO BE ASCERTAINED. [Communicated to him from abroad by Auguste
Guilbert-Martin, of Saint Denis près Paris, France, Chemist]
This Invention relates to an improved gauge glass or tube for the water gauges
of steam boilers and other liquid gauges, thermometers, barometers, and other
instruments in which the height or length of a column of liquid, particularly
transparent liquid, is required to be ascertained.
To enable the height of the liquid column to be more easily seen, such gauge
glasses and tubes have heretofore had a white stripe generally of enamel applied to
the tube in rear of the liquid column, but in consequence of the reflection of the
light by this white stripe and in the case of boiler gauges the condensation upon
the tube and the impurities of the water it is frequently difficult to ascertain the
precise level of the water except by applying the eye close to the gauge glass
which cannot in many cases be conveniently done.

page_text: This Invention has for its object to remedy this defect, and it consists in the
construction of a gauge glass or tube in which the white or reflecting stripe serves
only as a background for a narrower bright colored stripe which is sharply defined
thereon, the effect being that owing to the different refractive powers of the glass
and the liquid, a sharp clear, and accurate indication of the precise height of the
liquid column is afforded which is visible from a distance without liability of error.
In order that the Invention may be more readily understood, I have represented
an example thereof in the accompanying drawings which illustrate the effect
produced by the magnifying or lens like action of the liquid column in a water
gauge for steam boilers.
Figure 1 represents in vertical section a part of the gauge glass or tube empty;
Figure 2 a cross section of same on line 1-2 figure 1, and Figure 3 the gauge
glass or tube when partly filled with water.
In the manufacture of the gauge glass or tube a narrow stripe of bright colored
enamel a, red for instance, is first applied and over or behind this stripe a a wider
stripe of white enamel b forming a background or reflecting surface upon which
the stripe a shows up sharply.
As shown in Figure 3 there is a relatively considerable difference in the apparent
width of the stripe a above and below the top of the liquid column and moreover
at this precise point there is an apparent contraction of the width of the stripe a
which serves to mark still more clearly the top of the column.
It will be understood that the Invention is equally applicable and with
corresponding advantage to the tubes of thermometers, barometers, and other
instruments for indicating the height or length of a column of liquid, particularly a
transparent liquid.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Alexander Melville Clark in the Patent Office on the 17th April
1884.
ALEXANDER MELVILLE CLARK of the firm of A. M. and W. Clark of 53 Chancery
Lane in the County of Middlesex, Fellow of the Institute of Patent Agents.
"AN IMPROVEMENT IN GAUGE GLASSES OR TUBES FOR THE WATER GAUGES OF
STEAM BOILERS AND FOR OTHER LIQUID GAUGES APPLICABLE ALSO TO CERTAIN
OTHER INSTRUMENTS IN WHICH THE HEIGHT LENGTH OR POSITION OF A LIQUID
COLUMN IS TO BE ASCERTAINED," A communication to me from abroad by
Auguste Guilbert Martin of Saint Denis près Paris, France, Chemist
This Invention relates to an improved gauge glass, or tube for the water gauges
of steam boilers, applicable also for thermometers, barometers, and other instru-
ments in which the height or length of a column of transparent liquid, is required
to be ascertained.
To enable the height of the liquid column to be more easily seen, such gauge
glasses and tubes have heretofore had a white stripe generally of enamel applied
to the tube in rear of the liquid column, but (in the case of boiler gauges) in
consequence of the condensation within the tube and the impurities of the water it
is frequently difficult to ascertain the precise level of the water except by applying
the eye close to the gauge glass which cannot in many cases be conveniently done.
This Invention has for its object to remedy this defect, and it consists in the
construction of a gauge glass or tube in which the white or reflecting stripe serves
only as a background for a narrower bright coloured stripe which is sharply
defined thereon, the effect being that by reason of the different refractive powers
of the glass and the liquid, a sharp, clear, and accurate indication of the precise
height of the liquid column is afforded which is visible from a distance without
liability of error.
In order that the Invention may be more readily understood, I have represented
an example thereof in the accompanying drawings which illustrate the effect
produced by the magnifying or lens like action of the liquid column in a water
gauge for steam boilers.
Figure 1 represents a front view of part of the gauge glass or tube empty;
Figure 2 is a cross section of the same and Figure 3 represents the appearance of
the colored stripe when the gauge glass or tube is partly filled with water.
In the manufacture of the gauge glass or tube a narrow longitudinal stripe of
bright colored enamel a, red for instance, is first applied to the rear side of the tube
and over or behind this stripe a a wider stripe of white enamel b forming a
background or reflecting surface upon which the stripe a shows up sharply.
As shown in Figure 3 the portion of the tube containing the liquid acts as a lens
and magnifies the width of the colored stripe a so that there is a relatively
considerable difference in the apparent width of the colored stripe a above and
below the top of the liquid column and moreover at this precise point there is an
apparant contraction of the width of the stripe which serves to mark still more
clearly the top of the column.
Having described the nature of the said Invention and the manner of performing
the same I would observe that I do not make any claim to the application of a
single broad band of enamel but what I claim as the Invention to be protected by
the hereinbefore in part recited Letters Patent is:
A gauge glass or tube having a relatively narrow longitudinal stripe of colored
enamel applied to its rear side in combination with a broader band of white enamel

page_text: applied behind the colored stripe to form a background or reflecting surface upon
which said colored stripe is sharply defined substantially as described and for the
purpose specified.
In witness whereof I the said Alexander Melville Clark have hereunto set
my hand and seal this seventeenth day of April A.D. 1884.