IMPROVEMENTS IN HYDROMETERS FOR MEASURING THE DENSITY OF LIQUIDS OR The Specific GRAVITY OF SOLID SUBSTANCES
Year: 1876

page_text: LETTERS PATENT to Henry Negretti and Joseph Warren Zambra, of Holborn
Viaduct, in the City of London, Philosophical Instrument Makers, for the
Invention of "IMPROVEMENTS IN HYDROMETERS FOR MEASURING THE DENSITY
OF LIQUIDS OR The Specific GRAVITY OF SOLID SUBSTANCES."
Sealed the 21st October 1876, and dated the 3rd May 1876.
PROVISIONAL SPECIFICATION left by the said Henry Negretti and Josephi
Warren Zambra at the Office of the Commissioners of Patents on the 3rd May
1876.
HENRY NEGRETTI and JOSEPH WARREN ZAMBRA, of Holborn Viaduct, in the
City of London, Philosophical Instrument Makers. "IMPROVEMENTS IN HYDRO-
METERS FOR MEASURING THE DENSITY OF LIQUIDS OR THE SPECIFIC GRAVITY OF
SOLID SUBSTANCES."
Our Invention of improvements in hydrometers has for its object to construct
instruments of this class in such a manner that they will not be so liable to bo
broken or damaged by accident as instruments of the ordinary construction.
Hydrometers, saccharometers, and other instruments of that class are usually
constructed of glass, and consist of a hollow glass vessel, bulb, or float provided with
a hollow glass stem, which carries a graduated scale and with a weight below for
maintaining the instrument in a vertical position. It has been found in practice
that the weakest part of the instrument is the point of junction between the hollow
scale tube and the bulb or float, and that the instruments are more liable to break
at that point than at any other part.
In order to strengthen the instrument at this weak place we enclose within the
tubular stem a piece of glass tube, which extends from nearly the top of the tubular
stem down through the bulb or float to the bottom thereof, where its lower end is
secured by cement in any convenient manner. By this construction of parts the
internal tube takes the strain and relieves the tubular stem from the strain to which
it is subjected in instruments of the ordinary construction.
Another mode of effecting the same object is to form the tubular stem and the
bulb or float separately, and then connect them together by means of a short metal
pin, stud, or tube, which is cemented, screwed, or otherwise secured by one end
into the lower end of the tubular stem and by the other end into the upper end of
Drive Cl

page_text: the bulb or float. Platinum wiro is the substance we have found to be suitable
for this purpose, but we do not confine ourselves thereto as other metals may bo
found to answer. The tough piece of inetal will thus take the strain, and being
flexible or clastic will not bo liable to be broken by ordinary usage.
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 3rd November 1876.
HENRY NEGRETTI and JOSEPH WARREN ZAMBRA, of Holborn Viaduct, in the
City of London, Philosophical Instrument Makers. "IMPROVEMENTS IN HYDRO-
METERS FOR MEASURING THE DENSITY OF LIQUIDS OR THE SPECIFIC GRAVITY OF
SOLID SUBSTANCES."
Our Invention of improvements in hydrometers has for its object to construct
instruments for determining the density of liquids and the specific gravity of solids
in such a manner that they will not be so liable to be broken or damaged by accident
as instruments of the ordinary construction.
Hydrometers, saccharometers, and other instruments of that class, are usually
constructed of glass, and consist of a hollow glass vessel, bulb, or float provided with
a hollow glass stem, which carries a graduated scale and with a weight below for
maintaining the instrument in a vertical position. It has been found in practice
that the weakest part of the instrument is the point of junction between the hollow
scale tube and the bulb or float, at which point they are very liable to break.
In the accompanying Drawing we have shown two modes of strengthening
the instrument at the junction of the float and the stem.
In Fig. 1 A is the float made of glass, and carrying at its lower end the bulb B
containing mercury for weighing the instrument; C is the hollow glass stem rising
from the top of the float A.
*
In order to strengthen the instrument at the point of junction of the float A
with the stem C, we insert in the instrument before closing tho stem a piece of
glass or other tube D, which extends from nearly the top of the stem C down
through the bulb or float to the bottom thereof, where its lower end is secured to
the float by cement in any convenient manuer. The graduated scale may be
inserted with the rod D), and when the instrument is properly adjusted the tube C
may be sealed as usual.
In lieu of the glass strengthening rod Da tubo of stiff paper, on which the scale
is marked, may be used instead of the glass tube, or a wooden rod, or light reed,
round which the paper scale is lapped, may be employed, but in all cases it is
essential that the internal tube or rod for strengthening the instrument should fit
the hollow stem and extend down to the bottom or lower part of the bulb where
it is to be fixed in any convenient manner. By this construction of parts the
internal tube or rod takes the strain, and relieves the stem C from the strain to
which it is subjected in instruments of the ordinary construction.
Another mode of effecting the same object is shown at Fig. 2. In this case the
tubular stem C and the bulb or float A are formed separately, and connected
together by means of a short metal pin or tube D, which is secured in place by
fusing the glass on to the metal coupling piece. Platinum wire is the substance
we have found to be suitable for the coupling piece, but we do not confine ourselves
thereto, as other comparatively soft metals may answer the purpose. The insertion
of this metal junction picco will, like the rod in the first described arrangement,
impart strength to the instrument at that part at which experience has shewn it
was very liable to break.
Having now set forth the nature of our Invention of "Improvements in Hydro-
meters for Measuring the Density of Liquids or the Specific Gravity of Solid

page_text: Substances," and explained the manner of carrying the same into effect, we wish
it to be understood, that under the above in part recited Letters Patent we claim,
strengthening hydrometers constructed of glass in the manner and for the purpose
above described.
In witness whereof, I, the said Henry Negretti, hereunto set my hand
and seal, this Third day of November, in the year of our Lord One
thousand eight hundred and seventy-six.