Annals of the Astronomical Observatory of Harvard College Volume 42 (Paperback)

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. 1897 edition. Excerpt: ...VlII., used from August 4, 1894, to September 21, 1895, the bulb was protected from insolation and radiation by arching a sheet of aluminium over the bulb, and enclosing the entire instrument in an inverted basket, through which the wind could blow freely. Comparisons between the standard thermometer in the Observatory shelter and the records of the instrument, when swinging from the kites within 30 meters of the ground, showed that this exposure was fairly satisfactory. In the meteorograph used from November 16, 1895, to April, 1896, and occasionally in May and June, 1896, (Plate IV. Figure 30, ) the thermograph bulb was exposed beneath the instrument, and was well shaded, but the temperature was found to be considerably raised by insolation, perhaps on account of conduction of heat through the case. However, it is assumed that, at the small altitudes reached by this instrument, the insolation was virtually the same as near the ground, and that the correction required to reduce the readings to that of the standard thermometer in the shade, found when the instrument was near the ground and in full sunlight, can be applied to the records obtained at greater altitudes, in order to get the true air temperature. In other words, the condition remaining the same, it is assumed that the instrument recorded the correct fall or rise of temperature between successive altitudes. Hence the temperatures corrected to the Observatory standard by applying a correction determined at the beginning and end of each flight of the kites are given in Table XVII. The records of the third meteorograph (Plate VIII.) begin with Table XVIII. With this instrument, a screen which is described by Mr. Fergusson and shown on Plate IV. Figures 35 and 36, was adopted after..