F 16-
Hygrometric Tables.-The question of improved hygrometric tables and methods has been considered in correspondence with the British Meteorological Office, but owing to the war no definite scheme of improvement has been decided upon. 3,375 observations of the effect of an electric fan on the wet bulb thermometer in the "Indian" shelter at this Observatory have been discussed. It appears that the quantities given in the following table should be subtracted from the readings of the wet bulb thermometer in this form of shelter, at varying wind velocities and for varying depressions of the wet bulb:--
Corrections to be applied to the readings of an unaspirated wet bulb thermometer in an “Indian” shelter to reduce them to those of an aspirated thermometer, at different wind velocities and for different depressions of the wet bulb.
Wind velocity. m. p. h. ♡ ດ C 3° © + D - t' (Fah). 6° о F о 8° 9° 10° 3 4 เค 5 .6 0 10 *2 *3 4 *5 2 mi 100 'I 2 *3 4 3 2 *3 4 8766 4 *I '2 *3 5 6 I *3 4 זי '2 *2 *I *2 4 * I 'I *2 *3 9 'I *I 2 *3 *3 10 'I *3 I I 2 *2 *3 O * .8 '7 90 MN in in + I'O I'2 13 *9 I'I 1'2 '9 I'I -8 ΙΟ ·8 '9 .8 ·6 .6 '5 4 *3 12 *2 '2 *2 13 · I 'I "2 *2 *2 2 14 'I *I I -2 '2 15 'I I I 'I 16 *I 'I *I 17 'I 'I *I *I 1 'I 18 'I 'I 19 *I * I *I "I '1 ... 20 זי 21 22The wind velocity in the above table is that recorded by the Beckley Anemograph, the cups of which are 45 feet above the ground. Mean results suggest that the correction may be about a tenth of a degree less with east winds than with winds from other quarters, though the observations are discordant and this cannot be definitely accepted at present. In any case the amount is almost negligible and indicates that the exposure is satisfactory.