F 14
about 3 a.m. in the spring and autumn. The minimum intensity occurred at about 9 or 10 a.m. The maximum monthly intensity, 4·29, occurred in May with a shallow secondary maximum, 2·91, in August, and the minimum intensity, 1·71, in November.
The times are approximate and refer to Hongkong Standard Time (8 hours East of Greenwich).
Upper Air Research—40 flights with pilot balloons were made during the year. The results of the observations have been sent to the Commission International pour l'exploration de la haute atmosphère, Kristiania.
The Military Authorities very kindly placed at my disposal the services of two N.C.O.'s of the Corps of Royal Engineers to assist in this work, and two double theodolite ascents were made, the secondary station being the top of the time-ball tower. As the distance from the Observatory is only 2,055 feet, however, the results were not satisfactory above about 5,000 feet.
It is hoped that a more suitable secondary station may be found.
Up to the time of writing last year's report only two balloons had been found defective. During the past year, however, many such have been found. In future, small monthly shipments will be ordered.
Wind Tables. Tables for deriving the resultant direction and velocity of the wind from the north and east components were completed in the spring. They give direction from 0° to 360° to single degrees, and velocity, to tenths of a mile, for north and east components from +33 to -33 miles, by tenths of a mile from 3 to -3 miles and by single miles for the remainder. The object of the tables is to obtain the correct quadrant for the direction without mental effort on the part of the computer.
Effect of fan on wet bulb thermograph.—In the following table are given the revised corrections to the readings of an unaspirated wet bulb thermometer in an "Indian shelter" to reduce them to those of a whirled thermometer, at different wind velocities, and for different depressions of the wet bulb. The results are based on about 1,500 measures of the effect of an electric fan playing on to the wet bulb thermometer of the thermograph for the last 5 minutes of each hour. Only those hours have been used in which the register is sufficiently smooth to enable the effect of the fan to be measured with certainty.
The corrections are slightly larger than those given in the 1918 Report, indicating that aspiration for one minute is not sufficient. The wind velocity in the table is that recorded by the Beckley anemograph using the old factor 3. The cups of the anemograph are 45 feet above the ground.
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F 14
about 3 a.m. in the spring and autumn. The minimum intensity occurred at about 9 or 10 a.m. The maximum monthly intensity. 4-29, occurred in May with a shallow secondary maximum, 2·91, in August, and the minimum intensity, 171 in November.
The times are approximate and refer to Hongkong Standard Time (8 hours East of Greenwich).
Upper Air Research-40 flights with pilot balloons were made during the year. The results of the observations have been sent to the Commission International pour l'exploration de la haute atmosphere, Kristiania.
The Military Authorities very kindly placed at my disposal the services of two N.C.O.'s of the Corps of Royal Engineers to assist in this work, and two double theodolite ascents were madė, the secondary station being the top of the time-ball tower. As the distance from the Observatory is only 2,055 feet, however, the results were not satisfactory above about 5,000 feet.
It is hoped that a more suitable secondary station may found.
be
Up to the time of writing last year's report only two balloons had been found defective. During the past year however many such have been found. In future small monthly shipments will be ordered.
Wind Tables. Tables for deriving the resultant direction and velocity of the wind from the north and east components were completed in the spring. They give direction from 0° to 360° to single degrees, and velocity, to tenths of a mile, for north and east components from +33 to -33 miles, by tenths of a mile from 3 to -3 miles and by single miles for the remainder. The object of the tables is to obtain the correct quadrant for the direction without mental effort on the part of the computer.
Effect of fan on wet bulb thermograph.-In the following table are given the revised corrections to the readings of an unaspirated wet bulb thermometer in an "Indian shelter to reduce them to those of a whirled thermometer, at different wind velocities, and for different depressions of the wet bulb. The results are based on about 1,500 measures of the effect of an electric fan playing on to the wet bulb thermometer of the thermograph for the last 5 minutes of each hour. Only those hours have been used in which the register is sufficiently smooth to enable the effect of the fan to be measured with certainty.
The corrections are slightly larger than those given in the 1918 Report, indicating that aspiration for one minute is not sufficient. The wind velocity in the table is that recorded by the Beckley anemograph using the old factor 3. The cups of the anemograph are 45 feet above the ground.
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