IMPROVEMENTS IN THERMO-
Year: 1874

page_text: LETTERS PATENT to Henry Negretti and Joseph Warren Zambra,
both of Holborn Viaduct, in the City of London, Meteorologic a
Instrument Makers, for the Invention of "IMPROVEMENTS IN THERMO-
PROVISIONAL SPECIFICATION left by the said Henry Negretti and
Joseph Warren Zambra at the Office of the Commissioners of
Patents, with their Petition, on the 8th January 1874.
We, HENRY NEGRETTI and JOSEPH WARREN ZAMBRA, both of
Holborn Viaduct, in the City of London, Meteorological Instrument
Makers, do hereby declare the nature of the said Invention for “Im-
PROVEMENTS IN THERMOMETERS USED IN DEEP SEA SOUNDINGS, AND FOR OTHER
PURPOSES," to be as follows:-
Hitherto great difficulties have arisen in ascertaining the temperature
of the sea at any desired depth, owing to the fact that the various
temperatures of the different currents through which the thermometer
has to pass in descending or ascending will cause the instrument to vary.

page_text: in some cases very considerably, thus almost entirely frustrating the end
in view.
The object of the present Invention is to construct a self-registering
thermometer which may be used in deep sea soundings or in other
places not easy of access, whereby the correct temperature at any desired.
depth or position may be obtained without the slightest risk of error.
To this end we form an obstruction in the thermometer tube (by pre-
ference near the bulb) which we term the "breaking point," and at the
top of the tube we place a small reservoir.
The mode of working the instrument is as follows:-The thermometer
having been verified with a test thermometer is allowed to descend bulb
downwards to the required depth where it remains a few minutes in
order that it may register the correct temperature at that point, its
position is then suddenly reversed by means of a cord or other arrange-
ment and the amount of mercury at the time above the "breaking point'
is allowed to flow to the top of the tube, whence, it runs into the small
reservoir.
"
The thermometer having been allowed to resume its normal position
is pulled up when it is to be. again verified with the test thermometer,
it will then be found that a certain number of degrees are wanting. The
number of these degrees which will indicate the temperature of the sea
or other place at the time when the position of the thermometer was
reversed can be ascertained by deducting the reading of the improved
thermometer from that of the test thermometer.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Henry Negretti and Joseph Warren Zambra in the
Great Seal Patent Office on the 8th July 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, HENRY
NEGRETTI, and JOSEPH WARREN ZAMBRA, both of Holborn Viaduct, in
the City of London, Meteorological Instrument Makers, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighth day of January, in the year
of our Lord One thousand eight hundred and seventy-four, in the thirty-
seventh year of Her reign, did, for Herself, Her heirs and successors,

page_text: give and grant unto us, the said Henry Negretti and Joseph Warren
Zambra, Her special licence that we, the said Henry Negretti and
Joseph Warren Zambra, our executors, administrators, and assigns, or
such others as we, the said Henry Negretti and Joseph Warren Zambra,
5 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 THERMOMETERS USED FOR DEEP SEA SOUNDINGS, AND FOR OTHER
PURPOSES," upon the condition (amongst others) that we, the said Henry
Negretti and Joseph Warren Zambra, 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
3 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 Henry 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) :—
Hitherto great difficulties have arisen in ascertaining the temperature
of the sea at any desired depth owing to the fact that the various
temperatures of the different currents through which the thermometer.
has to pass in descending or ascending will cause the instrument to vary
in some cases very considerably, thus almost entirely frustrating the end
in view.
The object of the present Invention is to construct a self-registering
thermometer which may be used in deep sea soundings or in other
places not easy of access, whereby the correct temperature at any desired
depth or position may be obtained without the slightest risk of error.
To this end we form an obstruction in the thermometer tube (by
preference at or about zero or near the bulb) which we term the
'breaking point" and at the top of the tube we place a small reservoir

page_text: which may be made in the form of a tube or a prolongation of the
thermometer tube, or it may consist simply of a bulb into which a
portion of the mercury may be run, as and for the purpose hereafter
explained. The instrument is mounted on a centre pin or in a case or
frame in which it may be turned, so that its position may be reversed
when required.
In the accompanying Drawing Fig. 1 is a front view of one of the
improved thermometers drawn on an enlarged scale.
a, a, is the capillary tube of the thermometer; b, the breaking point
above mentioned and from which the mercury in the tube will break
away when the instrument is reversed and will run into the bulb or
reservoir c, which when the instrument is turned over will of course
be at the bottom; d is a test thermometer which is placed alongside of
the other tube for the convenience of reference; Fig. 2 is a front view
of the upper end of another instrument in which the reservoir to receive
the mercury from the capillary tube is formed by prolonging the tube
and forming a bulb at the upper end and then bending this end round,
as shown in the Drawing; Fig. 3 is another modification in which
the tube a is still further increased in length, and in fact to such an
extent that the elongated reservoir thus obtained will be long enough to
form a second mercurial tube a* to which may also be adapted a scale of
degrees as shewn in the Drawing and from which may be read off the
temperature indicated by the column of mercury that has been run from
the tube a.
In order to preserve the instrument from injury it may be placed in a
metal case provided with a pin or pivot on which it may be turned over
when it is required to be reversed, and when thus protected and ready
for use it is placed in a metal frame in which it may be turned over
when required:
On the centre pin or pivot on which the thermometer is mounted is
a small toothed wheel into which gears another wheel on the axle
of which is mounted a fan or blade like the blade of a propeller
which will point upwards while the instrument is descending through
the water, but immediately the instrument begins to ascend the position
of the blade will be reversed, that is, it will be made to point downwards.
This simple motion or half turn of the blade will through the gearing
give a whole turn to the thermometer and consequently will cause the

page_text: mercury in the bulb a to break away from the point 6 and run into the
tube a* in which it will remain until the instrument is drawn up to the
surface, the instrument having at the same time (by the whole turn that
has been given to it) regained its normal position. Various other
methods may be used for turning the thermometer on its centre pin
such as by means of a simple pulley with a weight which might be
released on touching the bottom. Or instead of the fan or blade above.
mentioned a small vertical propeller may be made to drive the gearing
when the instrument is being drawn up.
We would here remark that in order to avoid errors a catch should be
provided to prevent the instrument from making more than one turn, or
from turning back when it has been once rotated.
The mode of taking an observation with the instrument shown at
Fig. 3 is as follows:-The instrument having been sunk to the desired
depth and reversed in position in the manner described is drawn up to
the surface, and supposing the temperature above to be fifty degrees and
at the bottom of the sea forty degrees, the mercury will have sunk in a
to forty degrees; then upon reversing the instrument while at the bottom
of the sea all the mercury between the point 6 or zero and forty degrees
will run into the tube a* in which it will on rising to the surface indicate
forty degrees while the mercury in the bulb of the tube a will on being
brought to the surface rise in the latter tube to ten degrees, thereby
indicating that there is a difference in temperature between the surface
and the bottom of ten degrees, and that the temperature there is forty
degrees.
The mode of working the instrument, shown at Figures 1 and 2, is as
follows: The thermometer having been verified with a test thermo-
meter is allowed to descend bulb downwards into the sea to the required
depth, where it should be allowed to remain a few minutes in order that
it may register the correct temperature at that point. Its position is
then to be suddenly reversed by turning it over on its centre pin by
'means of either of the devices above described, and the amount of
mercury at the time above the "breaking point" will break away from
the breaking point and will flow to the top of the tube, whence it will
run into the small reservoir at the end of the tube, where it will remain
when the instrument resumes its normal position.
The thermometer having been allowed to resume its normal position.

page_text: is pulled up, when it may be again verified with the test thermometer.
It will then be found that a certain number of degrees are wanting;
the number of these degrees will indicate the temperature of the sea or
other place at the time when the position of the thermometer was
reversed, and this temperature can be ascertained by deducting the
reading of the improved thermometer from that of the test thermometer,
which will of course be the same as that of the improved thermometer
before it was sunk to the bottom of the sea.
It will be obvious that our improved thermometer may also be used
for making meteorological observations on land and for ascertaining
temperatures at stated times, for which purpose the thermometer may
be connected with clockwork (such as that used for alarum clocks),
whereby the thermometer will be turned over at any stated or desired
times, so that the temperature at that particular time may be read
subsequently.
Having now described our Invention of "Improvements in Thermo-
meters used for Deep Sea Soundings and for other Purposes," and
having explained the manner of carrying the same into effect, we claim
as the Invention secured to us by Letters Patent as aforesaid con-
structing thermometers with an obstructiou at or near the bulb and
with a reservoir or prolongation of the tube at the other end, into
which reservoir or prolongation all the column of mercury above the
obstruction or "breaking point" can be temporarily run, as and for the
purpose herein set forth.
In witness whereof, we, the said Henry Negretti and Joseph Warren
Zambra, have hereunto set our hands and seals, the Eighth
day of July, in the year of our Lord One thousand eight hundred