IMPROVEMENTS IN Manawaz MT
Year: 1862

page_text: LETTERS PATENT to Enrico Angelo Ludovico Negretti, and Joseph
Warren Zambra, both of Hatton Garden, in the City of London, Meteoro-
logical Instrument Makers, for the Invention of "IMPROVEMENTS IN
Manawaz MT »
Sealed the 17th October 1862, and dated the 25th April 1862.
PROVISIONAL SPECIFICATION left by the said Enrico Angelo Ludovico
Negretti and Joseph Warren Zambra, at the Office of the Com-
missioners of Patents, with their Petition, on the 25th April 1862.
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 THE CONSTRUCTION OF MERCURIAL MINIMUM THERMOMETERS," to be as
follows:-
Our Invention of improvements in the construction of mercurial mini-
thermometers consists in the employment in minimum thermo-
meters of a platinum plug, such as we describe in the Specification of our
Patent for improvements in the construction of maximum thermometers,
dated March Eighth One thousand eight hundred and fifty-two, and numbered
14,002. This plug however need not be a fixture in any part of the tube,
but may be arranged to act as a kind of valve. Instead of being placed
between the bulb and the indicating tube, as in our improved maximum
thermometer, the plug must be placed behind the bulb, and so arranged

page_text: that when the mercury expands the latter will either pass the plug if a
fixture, or push it forward if adapted to act as a loose valve, but on a decrease
of temperature the piece of platinum, if loose, will follow the mercury until
it arrives at a contracted part of the bore, or if the plug be fixed, the
mercury will recede as far as the plug, and no further, (unless force be
applied,) owing to the affinity of mercury for platinum. An aluminium plug
or stopper may also be employed for effecting the same purpose.
Another mode of constructing a minimum thermometer consists in elongating
the bulb or making a double bulb, and causing the bulb end of the indicating
tube to dip into the neck of the bulb, or of the elongation of the bulb, or of
the neck between the two bulbs. This instrument is so adjusted and regulated
during the construction by the maker that the murcury in the bulb at the
ordinary temperature will come exactly to the end of the tube that dips into
the neck of the bulb. On an increase of temperature the mercury will rise
round the outside of the dipping end of the indicating tube in preference to
passing up the bore, but on a decrease of temperature, the mercury will first
recede in the elongated bulb, or neck of the double bulb until it reaches the
lower end of the dipping tube, and only remains in contact with the mercury
in the bulb by the attraction of cohesion of the last particle of mercury in the
bulb for the column of mercury in the indicating tube. By this attraction
of cohesion the column of mercury will be drawn back or down the indicating
tube to the minimum point. The mercury will then rise in the elongated
neck round the outside of the dipping end of the indicating tube, and even
on an increase of temperature this will take place instead of rising in the
indicating tube, as the mercury in the bulb will not be able to push forward
the mercury in the indicating tube without assistance.
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 25th October 1862.
::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-fifth day of April, in the year of our Lord One
thousand eight hundred and sixty-two, in the twenty-fifth year of Her reign,

page_text: 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 THE CONSTRUCTION OF MERCURIAL MINIMUM THERMOMETERS," 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 seals;
or under the hand and seal of one of us, should particularly describe and ascer-
tain 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 we, the said Enrico Angelo Ludovico Negretti
and Joseph Warren Zambra, 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, 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 the Construction of Mercurial Minimum
Thermometers" consists, firstly, in the employment in minimum thermometers"
of a platinum plug,.such as we described in the Specification of our Patent
for "Improvements in the Construction of Maximum Thermometers," dated
March Eighth, One thousand eight hundred and fifty-two, No. 14,002. This
plug, however, need not be a fixture in any part of the tube as described in
that Specification, but may be arranged to act as a kind of valve. Instead of
being placed between the mercurial bulb and the indicating tube, as in our
improved maximum thermometer above referred to, the plug in the minimum
thermometer must be placed behind the bulb, and so arranged, that when the
mercury expands; the latter will either pass the plug, if it be a fixture, into an
additional bulb or supplementary reservoir, as described in the Specification
of our Patent, dated Fifteenth October, One thousand eight hundred and
fifty-five, No. 2306, or, the mercury will push the plug forward if it be adapted
to act as a loose valve; but, on a decrease of temperature, the piece or plug

page_text: of platinum, if loose, will follow the mercury until it arrives at a contracted
part of the bore; or, if the plug be fixed, the mercury will recede from the
additional bulb or supplementary reservoir, and also from the connecting tube
as far as the plug, and no further, unless force be applied to detach the mer-
cury from the platinum. This part of our. Invention is based upon the affinity
of mercury for platinum, as the platinum plug will allow the mercury behind
it to glide past, but will hold on to and retain the column, and prevent it from
being detached from the platinum.until force be applied.
In the accompanying Drawing, Fig. 1 represents the bulb part of a minimum
thermometer, constructed according to our Invention, and drawn upon an
enlarged scale. a, is the ordinary mercurial bulb; b, the registering tube; c, an
additional bulb or supplementary reservoir placed behind the ordinary bulb a,
and connected therewith by a short tnbe d, which is of greater bore than the
registering tube 6. This short tube is partially choked by a plug e of platinum,
which may be either fixed or loose, provided it be prevented from getting into
the bulb a.
The operation of this instrument will be as follows: -The instrument is
set for observation by lowering the indicating tube until the end of the mercury
reaches the platinum plug, and is there held by the affinity of the platinum
for the mercury. The mercury in the indicating tube will then shew the
present temperature. Upon a decrease of temperature, the mercury will
recede in the indicating tube, and will continue so to do until the minimum
temperature is attained. Should any increase of temperature take place in
the meantime, the mercury, instead of rising in the indicating tube b, will pass
or push forward the platinum plug e, and will enter the supplementary
reservoir c. Then, should another decrease of temperature take place, say
below the minimum heretofore attained, the mercury will. first recede in the
supplementary reservoir or bulb c, until it reaches the platinum plug, which
will hold it there, and thereby indicate the former minimum temperature.
The mercury will, from its affinity for the platinum, recede no further there-
from, but will recede only in the indicating tube, and thereby indicate a further
decrease of temperature.
Another mode of constructing a minimum thermometer is shewn in Fig 2,
and consists in elongating the bulb, or making a double bulb a and a³, and
causing the bulb end of the indicating tube b to dip into that part which
forms the neck of the ordinary bulb a. This form may be considered as an.
elongation of the ordinary bulb, with a contracted part made therein. It will
be seen that the inner end of the registering tube b passes down through the
upper bulb a', and extends into the necks or contracted part between the two

page_text: bulbs a and a. The instrument is adjusted and regulated during construction
in such a manner that the mercury in the bulb a, at the ordinary temperature
will come exactly.to the end of the registering tube b, which extends down into
the neck or contracted part between the two bulbs. On an increase of
temperature the mercury will rise round the outside of the dipping end of the
indicating tube b into the upper bulb, in preference to passing up the bore of
the indicating tube, which will be more contracted than the space around it in
the neck of the bulb; but on a decrease of temperature, the mercury will first
recede from the upper bulb a', or from the neck or contracted part between
the two bulbs until it reaches the lower end of the tube b. When the
mercury in the tube is only in contact with the mercury in the bulb a, by the
attraction of cohesion of the last particle of mercury in the bulb for the
column of mercury in the indicating tube, the mercury in the latter will be
drawn back by the attraction of cohesion until it reaches the minimum point.
Upon an increase of temperature, the mercury will rise again in the neck or
contracted part round the outside of the dipping end of the indicating tube b,
instead of rising in the indicating tube itself, as the mercury in the bulb will
not be able to push forward the mercury in the indicating tube without
assistance.
Having now described this Invention of "Improvements in the Construction
of Mercurial Minimum Thermometers," 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 modes herein set forth of preventing the
mercury from rising in the indicating tube upon an increase of temperature
after the column has been drawn back by a fall in the temperature.
In witness whereof, we, the said Enrico Angelo Ludovico Negretti and
Joseph Warren Zambra have hereunto set our hands and seals, the
Twenty-fifth day of October, in the year of our Lord One thousand
eight hundred and sixty-two.
ENRICO ANGELO LUDOVICO NEGRETTI.
(L.B.)
JOSEPH WARREN ZAMBRA.
(LS.)