AN IMPROVED HEALTH INDICATOR OR INSTRUMENT TO BE USED IN THE DIAGNOSIS OF DISEASES
Year: 1874

page_text: PROVISIONAL SPECIFICATION left by Henry Negretti and Joseph
Warren Zambra at the Office of the Commissioners of Patents,.
with their Petition, on the 19th October 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 "AN
IMPROVED HEALTH INDICATOR OR INSTRUMENT TO BE USED IN THE DIAGNOSIS OF
DISEASES," to be as follows:-
Our Invention relates to that class of instruments popularly known as.
"clinical thermometers," which on being applied to the body of a
person will indicate whether such person be in health or not.
.
The instrument is constructed upon the principle that the body of a
healthy person should be at a given and well-known temperature, say
98° Fah.; if therefore the body of any one exceeds that temperature it
will indicate a state of fever, more or less acute. If, on the contrary,
the temperature of the body be below the normal state it will indicate
that there is a want of vital heat, and that the patient is in a low state
of health.
.

page_text: These instruments are not required and are never used to measure the
degree of heat present, or to which they are exposed, but only to indicate
whether the temperature of the body be either above or below the
normal point; for this reason therefore only a small portion of the
thermometer scale (or a very few degrees) is used, and the instruments
are made very sensitive. They cannot therefore be properly denominated
"thermometers ; as a matter of fact, however, these instruments have
usually been made with a tube having a very fine bore, and graduated
with a portion of the thermometric scale. The bulb is supplied with
mercury, which owing to the fineness of the bore it was difficult to see.
These instruments were also of an expensive character, and not likely
therefore to be used by any but professional men.
"
The object of our Invention is to popularize the use of instruments of
this class by so modifying their construction that they will be very
considerably reduced in price, the facility in reading them will be
increased, and the liability to derangement by accidents other than
breakage almost entirely prevented.
In carrying out our Invention we employ colored fusel oil or creosote
for the indicating column, as colored liquid is more easily seen than
the very fine column of mercury which has heretofore been employed in
instruments of this kind.
The tube of our improved instrument is made with a wide bore just
above the bulb, or a narrowed elongation of the bulb, such wide bore or
elongation of the bulb being of sufficient length and capacity to take
the column of colored liquid up to that point of temperature (as
indicated by a thermometer) at which it is required to take the medical
observation. At this point, say 90° of the thermometric scale, the bore is
gradually narrowed to a very fine one, so that from 90° up to, say, 100°,
the instrument will be very sensitive.
At some point on the glass tube is made a mark, which we will call
zero. This point if compared with a thermometer will be at about 98°,
which is said to indicate the temperature of good health. The tube is
then graduated into arbitrary divisions above and below this zero point,
and the colored liquid by rising above or falling below that point will
indicate either a feverish or a low state of health.
In constructing our improved instruments we prefer to use fusel
oil properly colored rather than alcohol, as fusel oil does not boil at

page_text: so low a temperature as water, and therefore should the instrument
become deranged by an air bubble getting into the bore it will only
be necessary to immerse the bulb in hot water, when the air bubble will
be driven into the air chamber above, and will remain there.
In order that observations may be taken at leisure and with accuracy,
we sometimes adapt to the outside of the tube a sliding index, which the
observer can slide up or down the tube to the point where the column
of fusel oil or other liquid has stopped. He may then remove the
instrument from the patient-and examine it at leisure.