Specification of Henry Negretti and Joseph Warren Zambra : health indicator.

  • Negretti, Henry.
Date:
1874
Catalogue details

Licence: Public Domain Mark

Credit: Specification of Henry Negretti and Joseph Warren Zambra : health indicator. Source: Wellcome Collection.

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    . Provisional Specification. Negretti 8f Zambra's Improved Health Indicator. 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 he 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 5 are made very sensitive. They cannot therefore he 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. 10 These instruments were also of an expensive character, and not likely therefore to he 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 15 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 20 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 i ^ the column of colored liquid up to that point of temperature (as 25 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 30 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. 35 In constructing our improved instruments we prefer to use fusel oil properly colored rather than alcohol, as fusel oil does not boil at