F 14
The ball is hoisted half mast at the 55th minute and full mast at the 57th minute. If the ball fails to drop at the correct time it is lowered at 5 minutes past the hour and the ordinary routine repeated at the following hour, if possible.
Time signals are also given at night by means of three white lamps mounted vertically on the Observatory radio mast. The lights are extinguished momentarily every second from 20h. 55m. to 21h. except at the 28th, 29th, 54th, 56th, 57th, 58th and 59th seconds, of each minute. The 21h. signals were repeated at midnight on December 31, the last signal indicating the close of the year 1930. The hours refer to Hong Kong Standard Time (8 hours east of Greenwich).
The timeball was dropped successfully 661 times. There was one failure, on September 4 at 16h, when the ball fell about 24 minutes before 16h, owing to the accidental discharge of the lock from the Observatory. The winding apparatus was damaged considerably, but repairs were expeditiously effected by Messrs. W. S. Bailey & Co., the apparatus being again in action on Sept. 7. The ball was not raised on Dec. 6 at 13h, and Dec. 7 at 10h, owing to electrical defects.
The error of the timeball was 0s.4 three times, 0s.5 twice, and -0s.9 once. On all other occasions the ball fell with error of 0s.3 or less.
The probable error of the time ball in each month of the past five years is given in the following table.
Probable Error of the Time Ball.
Month 1926 1927 1928 1929 1930 January +0.13 +0.14 +0.13 +0.10 +0.10 February +0.18 +0.12 +0.10 +0.10 +0.13 March +0.11 +0.10 +0.10 +0.12 April +0.13 +0.10 +0.10 +0.10 +0.16 May +0.10 +0.14 +0.10 +0.10 +0.15 June +0.10 +0.13 +0.20 +0.10 +0.14 July +0.10 +0.10 +0.11 +0.10 +0.10 August +0.10 +0.12 +0.20 +0.12 +0.12 September +0.10 +0.10 +0.11 +0.10 0 October +0.11 +0.11 +0.11 +0.10 +0.11 November +0.10 +0.10 +0.10 +0.11 +0.10 December +0.13 +0.13 +0.12 +0.14 +0.10 Means +0.12 +0.12 +0.12 +0.11 ±0.12