F 16
Batteries, Power Supply, &c.-The necessary current for the Time Service has been supplied by accumulator batteries, charged as found necessary from the alternating mains of the China Light and Power Co., Ltd., by the rotary converter or the Tungar rectifier.*
IX.-MISCELLANEOUS.
Seismograph.-No alterations were made to the seismograph during the year. New needle points were fitted as required. As against 202 in 1927, 183 earthquakes were recorded during the year 1928, one of which was felt at Hong Kong; at 10.58.30 p.m. on January 29. During a severe earthquake which occurred about 2500 kms. from Hong Kong, in the early morning of March 10, the seismogram showed an amplitude in a N-S direction of 98 mms. and in an E-W direction 78 mms.
The seismograms have been forwarded to the President of the International Seismological Committee, Oxford, to be dealt with.
Upper Air Research.-64 Balloon ascents were made during the year. 69 temperature flights were made in aeroplanes by Officers of the R.A.F., Kai Tak, and 2 by Officers of H.M.S. "Hermes". On July 23 Flying Officer F.M.V. May reached a height of 19,000 feet in 109 minutes, the temperature at this height being 25°7 (F).
The results of the Pilot balloon observations have been forwarded to the Secretary of the International Commission for the exploration of the upper air.
The results of the temperature flights have been tabulated and plotted. They show a mean lapse rate of 2.°78 (F) per thousand feet, up to 15,000 feet, in the Spring and 3.°00 (F) in the Summer. In the Autumn and Winter the observations are not sufficiently numerous to admit the calculation of even approximate mean values. The lapse rate of relative humidity is extremely variable in all seasons of the year. During the passage through cloud an increase of humidity will naturally be recorded, but even on clear days there appears to be no definite lapse rate, the humidity curves for individual flights being very irregular. On August 22, though cumulus clouds were prevalent up to 20,000 feet, the humidity fell from 84% at 7,000 feet to 33% at 14,000 feet. On several occasions a dry layer was found from 10,000 to 13,000 feet, between wet layers.
The following days were selected by the International Commission as days for international ascents:-March 12-17, July 17-19 and November 12-17. March was chosen as the "international month". From March 12-17 and November 12-17 the weather at Hong Kong was cloudy.
Visitors. His Excellency the Officer Administering the Government and Mrs. Southorn visited the Observatory on October 12.