A GLOBULAR-CYLINDER MANO- METER WITH DOUBLE CAPILLARY LOCK
Year: 1869

page_text: LETTERS PATENT to Charles Wenzelas Zenger, Charles Louis Strube,
and Leopold Merlett, Manufacturers, residing in Buckau, King-
dom of Prussia, for the Invention of "A GLOBULAR-CYLINDER MANO-
METER WITH DOUBLE CAPILLARY LOCK."
Sealed the 8th February 1870, and dated the 10th August 1869.
PROVISIONAL SPECIFICATION left by the said Charles Wenzelas
Zenger, Charles Louis Strube, and Leopold Merlett at the Office
of the Commissioners of Patents, with their Petition, on the 10th
August 1869.
We, CHARLES WENZELAS ZENGER, CHARLES LOUIS STRUBE, and
LEOPOLD MERLETT, Manufacturers, residing in Buckau, Kingdom of
Prussia, do hereby declare the nature of the said Invention for "A
GLOBULAR-CYLINDER MANOMETER WITH DOUBLE CAPILLARY LOCK," to be as
follows:-
This improved aeromanometer is intended to remove several of the
defects which have hitherto prevented the general application of these
instruments by substituting an equal scale of division for a graduated

page_text: scale, and by preventing the resisting liquid column from separating and
the gas or vapour from entering the acromanometer when a sudden
change of pressure takes place. The space of that part of the mano-
meter tube which is filled with air or other gas should be equal to the
unit of the volume of such gas; the tube need merely be supplied with
various diameters or cross lines, so that the contents of the sections of
the tube are in an inverse ratio to the pressure, for which reason the
tube is composed of picces the diameters of which vary in the above
ratio, so that not only for any number of atmospheres equal lines of
division are to be produced, but they may have any length and the
sections of the tube be made in any form, whether cylindrical, globular,
or otherwise; it is however in any case expedient to give the last section
a globular form, so that the manometer tube consists of cylindrical tube
sections of unequal diameters but equal lengths, and has a globe at
the upper end. The manometer is divided up to eight atmospheres,
is composed of four two inch tube sections, and the diameters are
calculated so that upon each pressure of two atmospheres one section
will be filled up, the resisting liquid will fill the first section with a
pressure of two, and the last cylindrical tube section with a pressure of
eight atmospheres, and the calculations can be so made as to render
an allowance for the retrograde pressure of the lifted liquid column
unnecessary. The manometer tube terminates at the top in a globe, the
other end being closed by fusion; however at each side thereof a
capillary opening is formed, which passes through close below the
tightening screw, and a second chamber communicates with the lower
end of the said tube by means of a capillary canal only, thus forming
a double capillary lock, so that by properly regulating the diameters, of
the capillary tubes the resisting fluid will upon sudden pressures always
rise or fall continuously without any danger that upon two rapid an ascent
or fall the liquid column would be dissevered and allow gas to rush into
the chambers. The quantity of the resisting fluid (mercury for instance)
is so large as always to cover the capillary canal, so that neither upon
sudden pressure nor when being removed and shaken would air or steam
be permitted to enter the first chamber where the manometer tube termi-
nates. The fixed. volume of air therefore always remains in the chamber
of the aeromanometer. The whole is protected from injury by a glass cover
fixed by a screw, which at the same time serves for fixing the scale of
division. The aeromanometer is applicable to steam boilers, gas-pres-
sure guages, wind guages, hydraulic manometers, and many other

page_text: purposes, and this form of double capillary lock with two chambered
vessels may likewise be very advantageously used for vacuum meters.
By the use of the double capillary lock they are unvarying in their
action and far less subject to derangement than spring manometers;
thus they are well suited to supersede the latter, as they will always
regain the level of zero, which as is well known is not the case with spring
manometers even after being but a short time in use on account of the
alteration of the elasticity of the springs.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Charles Wenzelas Zenger, Charles Louis Strube,
and Leopold Merlett in the Great Seal Patent Office on the 10th
February 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, CHARLES
WENZELAS ZENGER, CHARLES LOUIS STRUBE, and LEOPOLD MERLETT,
Manufacturers, residing in Buckau, Kingdom of Prussia, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Tenth day of August, in the year
of our Lord One thousand cight hundred and sixty-nine, in the thirty-
third year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto us, the said Charles Wenzelas Zenger, Charles
Louis Strube, and Leopold Merlett, Her special license that we, the
said Charles Wenzelas Zenger, Charles Louis Strube, and Leopold
Merlett, our executors, administrators, and assigns, or such others as
we, the said Charles Wenzelas Zenger, Charles Louis Strube, and Leo-
pold Merlett, our executors, administrators, and assigns, should at any
time agree with, and no others, from time to time and at all times.
thereafter during the term therein expressed, should and lawfully might
make, use, exercise, and vend, within the United Kingdom of Great
Britain and Ireland, the Channel Islands, and Isle of Man, an Invention
for "A GLOBULAR-CYLINDER MANOMETER WITH DOUBLE CAPILLARY LOCK,"
upon the
condition (amongst others) that we, the said Charles Wenzelas Zenger,
Charles Louis Strube, and Leopold Merlett, our executors or administrators,
by an instrument in writing under our, or their, or one of their hands
and seals, should particularly describe and ascertain the nature of the said

page_text: Invention and in what manner the same was to be performed, and
cause the same to be filed in the Great Seal Patent Office within
six calendar, months next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that we, the said Charles Wenzelas Zenger, Charles
Louis Strube, and Leopold Merlett, do hereby declare the nature of
our said Invention, and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following
statement, and accompanying Sheet of Drawings (that is to say) :-
Our improved manometer is intended to remove several of the defects
which have hitherto prevented the general application of these instru-
ments by substituting an equal scale of division for a graduated scale,
and by preventing the resisting liquid column from separating and the
gas or vapour from entering the aeromanometer when a sudden change
of pressure takes place. Suppose the space of that part of the mano-
meter tube which is filled with air or other gas to be equal to the
unit of the volume of such gas, the tube need merely be supplied with
various diameters or cross lines, so that the contents of the sections of
the tube are in an inverse ratio to the pressure, for which reason the
tube is composed of pieces of lengths which vary in diameter in the
above ratio, so. that not only for any number of atmospheres equal
lines of division are produced, but they may have any length and the
sections of the tube be made in any form, whether cylindrical, globular,
or otherwise. It is evident that the manometer tube may have any
shape, the simplest being the globular or cylindrical. It is however in any
case expedient to give the last section a globular form, so that the
manometer tube consists of cylindrical tube sections of unequal dia-
meters but equal lengths and has a globe at the upper end. To secure
the manometer against gas or vapours entering the air chamber a
double capillary lock is applied as will be seen from the subjoined
Drawing of our improved cylinder manometer. The manometer is
divided up to 8 atmospheres, is composed of four 2 inch tube sections,
the diameters of which are so calculated that upon cach pressure of 2
atmospheres one section will be filled up, the resisting liquid will fill
the first section with a pressure of 2 and the last cylindrical tube with a
pressure of eight atmospheres, and the calculations can be so made as to
render an allowance for the retrograde pressure of the lifted liquid
column unnecessary.
The manometer tube terminates at the top in a

page_text: globe, the other end being closed by fusion; however at each side thereof
a capillary opening is formed, which passes through close below the
tightening screw, so that upon a sudden change of pressure the resist-
ing liquid does not fill or empty the tube by jerks, but gradually. The
design shews a second chamber communicating with the lower end of
the said tube by means of a capillary channel only, thus forming a
double capillary lock, so that by properly regulating the diameters of the
capillary tubes the resisting fluid will upon sudden pressures always
rise or fall continuously without any danger that upon too rapid an
ascent or fall the liquid column would be dissevered and allow gas to
rush into the chambers. The quantity of the resisting fluid (mercury
for instance) is so large as always to cover the capillary canal, so that
neither upon sudden pressure nor when being removed and shaken
would air or steam be permitted to enter the first chamber wherein the
manometer tube terminates. The fixed volume of air therefore always
remains in the chamber of the aeromanometer. The whole is protected
from injury by a glass cover fixed by a screw, which at the same time
serves for fixing the scale of division. This aeromanometer is applica-
ble to steam boilers, gas pressure guages, wind guages, hydraulic mano-
imeters, and many other purposes, and this form of double capillary
lock with two chambers may likewise be very advantageously used for
vacuum meters. The tubes resist even a pressure of from 150 to 200
atmospheres, and when covered up by a strong coat of glass all danger
from bursting is removed, as the contents of the air chamber will never
exceed 1 to 1 cubic inches. Alteration of temperature will occasionally
produce a very trifling deviation from zero at the utmost of 1/10 or 1/20
of an atmosphere, which under the dimensions above stated will vary
one line only even under a fluctuation of temperature of 30° R. if we cal-
culate 10° R. as the temperature to begin with and 28" pressure, the lower
and therefore the widest tube will by its width shew a trifling alteration
of the level as regards zero, whereas a common aeromanometer tube
would under the same circumstances shew very considerable deviations
on account of its equal diameter. By the use of the double capillary
lock they are unvarying in their action and far less subject to derange-
ment than spring manometers; thus they are well adapted to supersede
the latter, as they will always regain the level of zero, which as is well
known is not the case with spring manometers even after being but a
short time in use on account of the alteration of the elasticity of the
springs. Nor are they (like the spring manometers) subject to sudden

page_text: deviations, for which reason spring manometers for a considerable time
mark incorrectly without such inacuracy being observed. The globular-
cylinder manometer is consequently excellently adapted and fitted to
supersede the spring manometer, as it substitutes variable spring elas-
ticity by invariable elasticity of gas and supplies a trustworthy and
durable instrument for measuring.
Having thus described the nature and particulars of our Invention
we claim, the improved manometer with a double capillary lock and
variable tube as herein described and illustrated in the accompanying
Sheet of Drawings.
In witness whereof, we, the said Charles Wenzelas Zenger, Charles
Louis Strube, and Leopold Merlett, have hereunto set our hands
and seals, this 4th day of February, in the year of our Lord
1970