F 15
Time Signals by Radio Telegraphy. In addition to the time signals given by the time ball, and on the radio mast, signals are broadcast at 10h. and 21h, by radio-telegraphy, via Cape d'Aguilar. Particulars of the programme are given in Government Notification No. 322 of the 1st June, 1928.
Observations of the rhythmic radio time signals emitted by Nauen at 8h. a.m. Hong Kong Standard Time, have been made daily, whenever possible, during the year. The observations have been utilised for clock regulation during cloudy weather.
Transit Instrument. - Routine transit and level observations were made by the Chinese computers throughout the year. The Collimation and Azimuth determinations, and occasional transit observations, were made by the Chief and First Assistants.
The number of observations in the years 1929 and 1930 was as follows:
1929 1930 Transits 1111 1078 Level determinations 562 546 Azimuth determinations (mark) 42 32 Azimuth determinations (transit of circumpolar stars) 271 238 Collimation determinations (mark) 47 35Clocks. Sidereal Clock, Cottingham and Mercer, No. 507, has been in use as the Observatory Standard throughout the year. Its performance was again marked by a steady increase of losing rate (with superposed fluctuations corresponding to variations of pressure in the clock case, due to temperature changes). This is probably due to an increase of about one inch of barometric pressure within the clock case, caused by gradual leakage during the year. The losing rate of the clock varied from -0s.28 on Feb. 18 to +0s.55 on Dec. 11.
The Leroy Mean Time Clock, No. 1350, was used for dropping the time ball, maintaining the electric time service in the Observatory, and sending hourly signals to the Railway, the 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 0.5s by the addition or withdrawal of weights. The Dent Mean Time Clock, No. 39740, is held in readiness as a substitute for Leroy No. 1350. It was not required for this purpose in 1930.