IMPROVEMENTS IN MOUNTAIN AND OTHER BAROMETERS."
Year: 1861

page_text: LETTERS PATENT to Enrico Angelo Ludovico Negretti and Joseph
Warren Zambra, both of Hatton Garden, in the City of London,
Meteorological Instrument Makers, for the Invention of "IMPROVEMENTS
IN MOUNTAIN AND OTHER BAROMETERS."
PROVISIONAL SPECIFICATION left by the said Enrico Angelo Ludovico
Negretti and Joseph Warren Zambra at the Office of the Commissioners
of Patents, with their Petition, on the 29th January 1861.
We, ENRICO ANGELO LUDOVICO NEGRETTI and JOSEPH WARREN ZAMBRA,
both of Hatton Garden, in the City of London, Meteorological Instrument
Makers, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN MOUNTAIN AND OTHER BAROMETERS," to be as follows:-
Our Invention of improvements in mountain and other barometers has for
its object to make these instruments of standard accuracy, stronger, more
portable, and less liable to derangement when being carried about than here-
tofore. This is effected by dispensing with the ordinary flexible cistern which
contains the mercury at the bottom of the instrument, and in adapting in lieu
thereof a rigid cistern constructed of glass and iron, or other suitable materials.
This rigid cistern is screwed at the upper part on to the rigid part of the
instrument, and is therefore moveable vertically on this fixed part, and by

page_text: simply turning the cistern round by hand it will be elevated on the screwed
end of the rigid part of the instrument until a cushion or pad placed on a
swivel at the bottom of the cistern is brought up against the open end of the
barometer tube, when the instrument will be "packed" or rendered portable
for carriage, at the same time the mercury in the cistern will be brought up
against the rigid part of the instrument, and is thereby prevented from moving
or shaking about. An ivory index, pin, or stud is attached to the lower end of
the instrument, and forms a neutral point for the level of the mercury being
enclosed within the cistern, and in order to adjust the instrument for use it
will only be necessary to unscrew and lower the cistern until the surface of
the mercury is level with the point of the index pin, stud, or neutral point.
In order to make the instrument mercury-tight, the screwed parts are provided
with leather or other washers.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Enrico Angelo Ludovico Negretti and Joseph Warren
Zambra in the Great Seal Patent Office on the 27th July 1861.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, ENRICO
ANGELO LUDOVICO NEGRETTI and JOSEPH WARREN ZAMBRA, both of Hatton
Garden, in the City of London, Meteorological Instrument Makers, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-ninth day of January, in the year of our
Lord One thousand eight hundred and sixty-one, in the twenty-fourth year
of Her reign, did, for Herself, Her heirs and successors, give and grant
unto us, the said Enrico Angelo Ludovico Negretti and Joseph Warren
Zambra, Her special license that we, the said Enrico Angelo Ludovico
Negretti and Joseph Warren Zambra, our executors, administrators, and
assigns, or such others as we, the said Enrico Angelo Ludovico Negretti
and Joseph Warren Zambra, 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
"IMPROVEMENTS IN MOUNTAIN AND OTHER BAROMETERS," upon the condition
(amongst others) that we, the said Enrico Angelo Ludovico Negretti and
Joseph Warren Zambra, by an instrument in writing under our hands and

page_text: seals, or under the hand and seal of one of us, 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 Enrico Angelo Ludovico Negretti, (on
behalf of myself and of the said Joseph Warren Zambra,) do hereby declare
the nature of the said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement, reference being had to the Drawing hereunto annexed, and to the
letters and figures marked thereon (that is to say) :-
Our Invention of improvements in mountain and other barometers has for
its object to make these instruments of standard accuracy, stronger, more
portable, and less liable to derangement when being carried about than here-
tofore. This is effected by dispensing with the ordinary flexible cistern which
contains the mercury at the bottom of the instrument, and in adapting in
lieu thereof a rigid cistern constructed of glass and iron, or other suitable
materials. This rigid cistern is screwed at the upper part on to the rigid
part of the instrument, and is therefore moveable vertically on this fixed part,
and by simply turning the cistern round by hand it will be elevated on the
screwed end of the rigid part of the instrument until a cushion or pad placed
on a swivel at the bottom of the cistern is brought up against the open end
of the barometer tube, when the instrument will be "packed" or rendered
portable for carriage, at the same time the mercury in the cistern will be
brought up against the rigid part of the instrument, and is thereby prevented
from moving or shaking about. An ivory index, pin, or stud is attached to
the lower end of the instrument, and being enclosed within the cistern forms
a neutral point for the level of the mercury; and in order to adjust the
instrument for use it will only be necessary to unscrew and lower the cistern
until the surface of the mercury is level with the point of the index, pin, stud,
or neutral point. In order to make the instrument mercury-tight, the screwed
parts are provided with leather or other washers.
In the accompanying Drawing, Fig. 1 is an elevation of one of our improved
instruments complete; Eig. 2-is a vertical section of the lower part of the
instrument drawn upon an- enlarged scale, in order that the construction of
the several parts may be more clearly seen.
The cistern is composed of a glass cylinder a, a, which is secured at each
end in a metallic tube or frame b. In order to render the instrument mer-
cury-tight at bottom, a metal cap c is screwed into the tube or frame b, and

page_text: bears against a leather or other washer a', a', which is placed between it and
the lower edge of the glass cylinder a. Another cap c' is adapted to the other
end of the metal tube b, and by screwing down the same on to the leather
washers or packing this packing is made to bind tightly on the screw of
the rigid part of the instrument. The mercury tube d is passed through
and secured in a block of soft porous wood e, which is fixed in the end of
the screwed socket f. This block e being porous will allow air to pass through
and act on the surface of the mercury in the cistern below, but it will be
sufficient to prevent the mercury from passing out of the cistern when the
instrument is "packed" or made portable. The screwed socket ƒ passes
through the metal tube or frame b, and may be screwed up or down therein
as may be required, as will be fully understood on reference to the Drawing
Fig. 2. On the upper end of the screwed socket f is screwed or otherwise
secured another metal tube 9, for the purpose of protecting the glass mercury
tube & from injury, and also forms what is usually denominated the "frame"
of the barometer. An ivory peg or point h is screwed into the under side of
the block of soft wood e, and its lower end forms the neutral point to which
the surface of the mercury in the cistern is to be adjusted when the instrument
is to be prepared for use and observation. It will be seen, on referring to
Fig. 2, that the lower end of the glass mercury tube is provided with an air
chamber d', into which any air that may accidentally enter the mouth of the
tubed will be received instead of entering the column of mercury in the
barometer tube d. A soft pad or cushion i is secured in a moveable socket,
which is capable of turning round horizontally on the screw j, whereby it is
connected with or secured to the cap c. This facility of turning round on its
centre is given to the pad i, in order that when the mercury tube d comes in
contact with it this tube may not be wrung or disturbed in its seat. The
cistern a may be filled with mercury by removing the screw k from the cap c,
and then pouring in the proper quantity of mercury, after which the screw k
may be replaced. When the several parts are in the position shewn in the
Drawing, the instrument will be in a state of adjustment ready to take an
observation, but when it is desired to render the instrument portable, it must
be inclined until mercury from the cistern fills the tube d; the cistern a, b,
must then be screwed up on the socket f, so as to bring the pad i up against
the open end of the mercury tube d, and the face of the cap c' is brought up
against the under side of the shoulder of the cover immediately above it;
the instrument may then be carried without being liable to derangement.
When it is desired to make a new observation, the instrument must be sus-
pended vertically by the ring m, (Fig. 1,) at top, and the cistern a, b, must then

page_text: be unscrewed until the surface of the mercury is brought just level with the
extreme end of the ivory point h, as shewn in the Drawing.
Having now described our Invention of improvements in mountain and
other barometers, and having explained the manner of carrying the same
into effect, we claim as the Invention secured to us by Letters Patent as
aforesaid, the mode herein set forth of constructing and adjusting the cistern
of barometers.
In witness whereof, I, the said Enrico Angelo Ludovico Negretti, have
hereunto set my hand and seal, this Twenty-seventh day of July, in
the year of our Lord One thousand eight hundred and sixty-one.
ENRICO ANGELO LUDOVICO NEGRETTI. (LS.)