Mr Glaisher's Ascents (cont'd): Objectives of Experiments; Instruments and Apparatus; Observing Arrangements.
The primary object was to determine the temperature of the air, and its hygrometrical state at different elevations to as great a heights as could be reached; and the secondary objects were -- (1) to determine the temperature of the dew --point by Daniel's and Regnault's hygrometers, as well as by the dry and wet bulb thermometers, and to compare the results; (2) to compare the readings of an aneroid barometer with those of a mercurial barometer up to the height of 5 miles; (3) to determine the electrical state of the air, (4) the oxygenic condition of the atmosphere, and (5) the time of vibration of a magnet; (6) to collect air at different elevations; (7) to note the height and kind of clouds, their density and thickness; (8) to determine the rate and direction of different currents in the atmosphere; and (9) to make observations on sound.
The instruments used were mercurial and aneroid barometers, dry and wet bulb thermometers, Daniell's dew-point hygrometer, Regnault's condensing hygrometer, maximum and minimum thermometers, a magnet for horizontal vibration, hermetically sealed glass tubes exhausted of air, and an electrometer. In one or two of the ascents a camera was taken up.
One end of the car was occupied by the aeronaut; near the other, in front of Mr. Glaisher, was placed a board or table, the extremities of which rested on the sides of the car; upon this board was placed suitable framework to carry the several thermometers, hygrometers, magnet, aneroid barometer, &c., a perforation through it admitted the lower branch of the mercurial barometer to descend below, leaving the upper branch at a convenient height for observing. A watch was placed directly opposite to Mr. Glaisher, the central space being occupied by his notebook. The aspirator (for Regnault's hygrometer) was fixed underneath the center of the board, so as to be conveniently workable by either feet or hands. Holes were cut in the board to admit the passage of the flexible tubes required for Regnault's hygrometer and the cry and wet bulb thermometers.
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