. The principles of hygiene; a practical manual for students, physicians, and health-officers . FlG. 2.—Daniells hygrometer : a, bulb surrounded with cotton cloth; b, ther-mometer; c, bulb containing thermometer. direct, as Daniells (Fig. 2), Dines, and Regnaults,and determine directly the dew-point of the atmosphere;or indirect, as the wet- and dry-bulb thermometer, orpsychrometer (Fig. 3), and the hair hygrometer (Fig. 4).The important items of information to be derived fromobservations with hygrometers are: The dew-point, thevapor-tension or absolute humidity, and the relative hu- 38 AIR. m
. The principles of hygiene; a practical manual for students, physicians, and health-officers . FlG. 2.—Daniells hygrometer : a, bulb surrounded with cotton cloth; b, ther-mometer; c, bulb containing thermometer. direct, as Daniells (Fig. 2), Dines, and Regnaults,and determine directly the dew-point of the atmosphere;or indirect, as the wet- and dry-bulb thermometer, orpsychrometer (Fig. 3), and the hair hygrometer (Fig. 4).The important items of information to be derived fromobservations with hygrometers are: The dew-point, thevapor-tension or absolute humidity, and the relative hu- 38 AIR. midity of the atmosphere. The dew-point is that tem-perature at which the air is saturated with moisture, sothat the least further fall in temperature causes a deposit of moisture in the form ofdew. The higher the tem-perature of the air, the largerthe amount of water it cancontain in the form of vapor;and if the temperature be low-ered, the amount of moistureremaining the same, eventu-ally a point will be reachedat which some of the moist-.
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Keywords: ., bookcentury1900, bookdecade1900, booksubjecthygiene, bookyear1901
