F 17
Post Office, the Telephone Co., and the Eastern Extension Telegraph Co. The clock is corrected daily before 10h. and 16h. by the electric regulating apparatus. The daily rate of the pendulum is kept below 0.5 sec. by the addition or withdrawal of weights. Mean Time clock Dent, 39740, has been corrected daily and its rate regulated as in the case of Leroy 1350.
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.-New mirrors were fitted to both components of the Milne-Shaw Seismograph, 202 earthquakes were recorded during the year as against 210 in 1926. A large earthquake was recorded on May 23. The amplitude was greater than in the Japanese earthquake of 1923, August 31-September 1. The seismograms have been forwarded to the President of the Seismological Committee, Oxford.
Upper Air Research.-11 flights with pilot balloons were made during the year, supplemented by 2 from H.M.S. "Argus" (Lieut.-Commander A. E. Dodington, R.N.) and 16 temperature flights in sea planes were made by Lieut.-Commander H. S. Murray Smith, R.N., who also observed upper air wind direction and velocity on four occasions, by means of smoke bursts from H.M.S. "Hermes" when at sea. Lieut.-Commander Dodington similarly observed wind direction and velocity on 2 occasions at Wei Hai Wei and on 4 occasions between Wei Hai Wei and Hong Kong.
The following days were selected by the International Commission as days for international ascents. February 15-17, June 13-18 and October 17-22. October was chosen as the "international month".
No balloon ascents were made from the Observatory on February 15-17 on account of cloud, but Lieut.-Commander Murray Smith secured temperature observations in a sea plane up to 14,400 feet on February 15 and up to 11,000 feet on February 16, under unfavourable conditions. On February 17 conditions were too bad for flying.
By the end of April our stock of hydrogen was exhausted owing to leakage from the cylinders, and no funds were available for a further supply. Temperature flights were made by Lieut.-Commander Murray Smith, however, at Hong Kong on June 15-18 and by Lieut.-Commander Dodington, off Shanghai, on June 14-17.