F 12
—
The figures in the above table include the number of hours that night signals, corresponding to the day signals, were hoisted.
The red signal indicates that a depression or typhoon exists which may possibly cause a gale at Hong Kong within 24 hours. The black signals indicate that a gale is expected at Hong Kong.
Three bombs fired at intervals of 10 seconds indicate that wind of typhoon force is anticipated.
Arrangements were made early in the year 1927 for the more rapid dissemination of typhoon warnings by telephone. The Observatory now warns 6 stations, 3 of which are distributing stations. Of these one warns 7 stations, 3 of which are distributing stations. Of the latter, one warns 11 stations, 2 of which are distributing stations. In all 86 stations or officials are warned. This service requires specially qualified operators at the Exchanges, who come on duty when the red signal is hoisted.
Special forecasts and storm warnings were issued to the Far Eastern Flight during their passage from Singapore to Hong Kong and return, in November.
VI. METEOROLOGICAL OBSERVATIONS FROM SHIPS, TREATY PORTS, &c.
Logs received. In addition to meteorological registers kept at about 40 stations in China, meteorological logs were received from 186 ships operating in the Far East. These logs, representing 9425 days' observations have been utilised for amplifying the weather maps and verifying typhoon tracks. The corresponding figures for the year 1927 were 169 and 7221.
Comparison of Barometers.-The corrections to ships barometers are usually obtained by comparing their readings while at Hong Kong with those of the Observatory Standard. Occasionally ship captains bring their barometers to the Observatory to be compared with the Observatory Standard.
VII. MAGNETIC OBSERVATIONS.
Routine magnetic observations were discontinued at the Royal Observatory at the end of 1927. From the beginning of 1928 Magnetic horizontal force, declination and dip have been determined at the Au Tau Station weekly, when possible. The instruments used are a magnetometer by Cooke, Troughton and Simms, No. 31, and an Earth Inductor by the Cambridge Instrument Co. C65818. In the following table are given the annual values of the magnetic elements in 1928 as derived from 40 determinations:-
Declination (West) Dip (North) Horizontal Force (C.G.S. unit) Vertical Force (C.G.S. unit) Total Force (C.G.S. unit) 0°43.1′ 30°38.8′ 0.37478 0.22207 0.43563