CERTAIN IMPROVEMENTS IN APPARATUS FOR ASCERTAINING THE PRESSURE OF STEAM, AIR, WATER, OR ANY OTHER FLUID OR LIQUID
Year: 1855

page_text: LETTERS PATENT to Frederic Ludewig Hahn Danchell, of No. 4, Arthur
Terrace, Caledonian Road, Islington, in the County of Middlesex, Civil
Engineer, for the Invention of "CERTAIN IMPROVEMENTS IN APPARATUS FOR
ASCERTAINING THE PRESSURE OF STEAM, AIR, WATER, OR ANY OTHER FLUID
OR LIQUID."
Sealed the 2nd May 1856, and dated the 6th November 1855.
PROVISIONAL SPECIFICATION left by the said Frederic Ludewig Hahn
Danchell at the Office of the Commissioners of Patents, with his Petition;
on the 6th November 1855.
I, FREDERIC LUDEWIG HAHN DANCHELL, of No. 4, Arthur Terrace,
Caledonian Road, in the Parish of Islington, in the County of Middlesex,
Civil Engineer, do hereby declare the nature of the said Invention for
"CERTAIN IMPROVEMENTS IN APPARATUS POR ASCERTAINING THE PRESSURE OF
STEAM, AIR, WATER, OR ANY OTHER FLUID OR LIQUID," to be as follows:
Instead of admitting the entire pressure of steam, air, water, or fluids or
liquids to act directly upon the indicating instrument for the purpose of shew-
ing the amount of such pressure, I only admit a part. Instead, therefore, of
a column of thirty inches of mercury for every fifteen pounds pressure, which
renders the ordinary mercurial guages of equal divisions impracticable for
high-pressure purposes, I obtain only such a column of mercury as will
correspond with that portion of pressure which I admit & make available;

page_text: and this enables me to reduce the scale of my mercurial guage to any length
most convenient to indicate any amount of pressure. I limit the quantity
of steam, air, or fluid which is to act upon the indicating instrument by
reducing the passage which admits the supply of the fluid, the pressure of
which is to be measured by the indicator; and I regulate my instrument or
apparatus by allowing one part of the fluid thus reduced to escape into the
atmosphere, while the other acts upon the guage.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Frederic Ludewig Hahn Danchell in the Great Seal Patent
. Office on the 6th May 1856.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, FREDERIC
LUDEWIG HAHN DANCHELL, of No. 4, Arthur Terrace, Caledonian Road,
Islington, in the County of Middlesex, Civil Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters.
Patent, bearing date the Sixth day of November, in the year of our Lord
One thousand eight hundred and fifty-five, in the nineteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Frederic Ludewig Hahn Danchell, Her special licence that I, the said
Frederic Ludewig Hahn Danchell, my executors, administrators, and assigns,
or such others as I, the said Frederic Ludewig Hahn Danchell, my 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 "CERTAIN IMPROVEMENTS IN APPARATUS FOR ASCERTAINING THE
PRESSURE OF STEAM, AIR, WATER, OR ANY OTHER FLUID OR LIQUID," upon the
condition (amongst others) that I, the said Frederic Ludewig Hahn Danchell,
my executors or administrators, by an instrument in writing under my, or
their, or one of their hands and seals, should particularly describe and ascertain
the nature of the said 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 I, the said Frederic Ludewig Hahn Danchell, do
hereby declare the nature of my said Invention, and in what manner the same

page_text: is to be performed, to be particularly described and ascertained in and by the
following statement thereof (that is to say):-
Instead of admitting the entire pressure of steam, air, water, or fluids or
liquids to act directly upon the indicating instrument, for the purpose of
showing the amount of the said pressure, I only admit a part of such pressure
to act directly or indirectly upon the said indicating instrument. Instead,
therefore, of a column of thirty inches of mercury for every fifteen pounds of
pressure, which renders the ordinary mercurial guages of equal division im-
practicable for high-pressure purposes, I obtain only such a column of mercury
as will correspond with that portion of pressure which I admit and make
available, and this enables me to reduce the scale of my mercurial guage to
I limit the
any lengths most convenient to indicate any amount of pressure.
quantity of steam, air, or fluid which is to act on the indicating instrument by
reducing the passage which admits the supply of the fluid, the pressure of
which is to be measured by the indicator; and I regulate my instrument or
apparatus by allowing one part of the fluid thus reduced to escape into the
atmosphere, while the other acts upon the guage.
Having thus stated the nature of my Invention, I will proceed to describe
the manner of performing the same.
DESCRIPTION OF THE DRAWING.
Figure 1 and Fig. 2 show each a front view, partly in section, of a pressure
a is a tube, fixed on the steam
guage constructed according to my Invention.
boiler or steam pipe of the boiler; the steam thus being capable of passing
through a into b, which presents two distinct passages, the one at d connected
with the guage f, and the other through g with the atmospheric air. It is
obvious, that if the opening c did not exist, the steam would cause the mercury
in the guage fto rise at the rate of thirty inches for each atmospheric pres-
sure; and it is equally obvious, that if the opening c would be of an equal area
with that of a, that then the whole force of the steam would escape out of this
said opening c without effecting any rise of the mercury, except perhaps a small
fraction, originating from a resistance caused by the friction of the steam in
passing through c. In determining the respective areas of a and c, after having
decided on the height of column for each atmosphere on my guage to be equal
to, say, one inch, then I have to divide this one inch into thirty, which gives
3. me 3, and make the area of c that much, namely th, smaller than that
of a, and therefore whatever part of thirty inches I intend to represent an
atmospheric pressure with, I have nothing to do but to make c the same
fraction smaller than a.

page_text: In Fig. 2 the same effect respecting the raising of the mercury is produced,
notwithstanding the passage d, which communicates with the guage f, is applied
on the opposite side of c to that which it is in Fig. 1; but then this said
passage d is also to be connected with the guage on the opposite side of the
mercury, and the relative proportions of the area of c to that of g be equal to
the column which is to represent an atmosphere on my guage to thirty inches
h, with a point capable to pass freely through the aperture ċ when pressed
forward, and intended to serve the purpose of clearing out this said aperture,
in case that, from the priming of the steam boiler or other causes, some uiatter
should stop it up.
Having thus described the nature of my Invention, and the manner of
performing the same, I would have it understood that what I claim is,-
First, the application of a certain arrangement in the passages of the steam
or other fluid, as herein explained, so as to enable me to produce a mercurial
guage of reduced size and equal division.
And, secondly, the application of the apparatus for clearing out the opening
in case of need, as also herein explained.
In witness whereof, I, the said Frederic Ludewig Hahn Danchell, have
hereunto set my hand and seal, this Sixth day of May, in the year
of our Lord One thousand eight hundred and fifty-six.
F. DANCHELL. (L.S.)