Inhaltsangabe
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1913 edition. Excerpt: ...69 and 70. Table 73 gives the weight of saturated aqueous vapor in grains per cubic foot for dew points given to every degree from--300 to + 200, to each half degree from + 200 to + 700, and for every o2 from 700 to H98 F, the values being computed to the thousandth of a grain. REDUCTION OF OBSERVATIONS WITH THE PSYCHROMETER AND DETERMINATION OF RELATIVE HUMIDITY. The psychrometric formula derived by Maxwell, Stefan, August, Regnault and others is, in its simplest form, e=e'-AB (-/'), in which t = Air temperature. /' = Temperature of the wet-bulb thermometer. e = Pressure of aqueous vapor in the air. e' = Vapor pressure, saturated, at temperature t'. B = Barometric pressure. A = A quantity which, for the same instrument and for certain conditions, is a constant, or a function depending in a small measure on /'. All pressures are expressed in heights of mercurial column under standard gravity. The important advance made since the time of Regnault consists in recognizing that the value of A differs materially according to whether the wet-bulb is in quiet or moving air. This was experimentally demonstrated by the distinguished Italian physicist, Belli, in 1830, and was well known to Espy, who always used a whirled psychrometer. The latter describes his practice as follows: "When experimenting to ascertain the dew-point by means of the wet-bulb, I always swung both thermometers moderately in the air, having first ascertained that a moderate movement produced the same depression as a rapid one." The principles and methods of these two pioneers in accurate psychrometry have now come to be adopted in the standard practice of meteorologists, and psychrometric tables are adapted to the use of a whirled or ventilated instrument. The...
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Reseña del editor
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1913 edition. Excerpt: ...69 and 70. Table 73 gives the weight of saturated aqueous vapor in grains per cubic foot for dew points given to every degree from--300 to + 200, to each half degree from + 200 to + 700, and for every o2 from 700 to H98 F, the values being computed to the thousandth of a grain. REDUCTION OF OBSERVATIONS WITH THE PSYCHROMETER AND DETERMINATION OF RELATIVE HUMIDITY. The psychrometric formula derived by Maxwell, Stefan, August, Regnault and others is, in its simplest form, e=e'-AB (-/'), in which t = Air temperature. /' = Temperature of the wet-bulb thermometer. e = Pressure of aqueous vapor in the air. e' = Vapor pressure, saturated, at temperature t'. B = Barometric pressure. A = A quantity which, for the same instrument and for certain conditions, is a constant, or a function depending in a small measure on /'. All pressures are expressed in heights of mercurial column under standard gravity. The important advance made since the time of Regnault consists in recognizing that the value of A differs materially according to whether the wet-bulb is in quiet or moving air. This was experimentally demonstrated by the distinguished Italian physicist, Belli, in 1830, and was well known to Espy, who always used a whirled psychrometer. The latter describes his practice as follows: "When experimenting to ascertain the dew-point by means of the wet-bulb, I always swung both thermometers moderately in the air, having first ascertained that a moderate movement produced the same depression as a rapid one." The principles and methods of these two pioneers in accurate psychrometry have now come to be adopted in the standard practice of meteorologists, and psychrometric tables are adapted to the use of a whirled or ventilated instrument. The...
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