65. 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-telegraph, via Cape d'Aguilar. Particulars of the programme are given in Government Notification No. 322 of the 1st June, 1928.
66. Observations of the radio time signals emitted by Nauen at 8h. a.m. Hong Kong Standard Time, have been made daily, whenever possible, during the year. They have been utilised for clock regulation during cloudy weather.
67. 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.
68. The number of observations in the years 1930 and 1931 were as follows:
1930 1931 Transits 1078 861 Level determinations 546 442 Azimuth determinations (mark) 42 34 Azimuth determinations (transit of circumpolar stars) 238 164 47 38 Collimation determinations (mark)69. Clocks 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 until September when the rate of increase became more rapid and the daily rate became unsteady. On October 12 the clock was dismantled for cleaning. The oil was found to have thickened in several of the pivot holes, but the pivots and teeth were in excellent condition. The electrical contact to actuate the remounting mechanism showed signs of wear and of sparking having taken place. The clock was re-assembled the same day and a new condenser placed across the terminals of the remounting contact. Its performance has since been very satisfactory. An increase of losing rate is again shown; probably due to a small leakage of the clock case.
70. 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 1931.