E 11
The ball was not raised on September 3 owing to strong wind. It fell with an error of 0°3 or less on 302 occasions, with an error of 0°4 or 0°5 on 35 occasions, and 0°6 or 0°7 on 14 occasions. Errors of 0°8 occurred twice, of 0°9 four times, of 1°0 three times, and 1°1 and 1°2 once each. The probable error varied from 0°14 in February, September and October, to 0°28 in December.
A proposal to heighten the time-ball tower, and also the mast, is under consideration. In the month of March the time-ball wire was run on Government poles along the railway to prevent interference and accidental earthing, or contact with other lines.
Transit instrument.—Observations for time were made daily with the 3-inch transit instrument and the Hipp tape chronograph by the Chinese computers, weather permitting.
The number of observations in the years 1913 and 1914 were as follows:—
1913 1914 Transits, 1,118 1,803 Level determinations, 308 893 Azimuth 80 47 Collimation 47 43Transits of the sun were only observed when star transits were not available from the previous night.
The azimuth and collimation determinations were made by the Chief or First Assistant, usually once a week. The azimuth determinations depend usually on observations of the north and south marks.
A new object glass was fitted on January 4. The value of one revolution of the micrometer screw was re-determined on January 6 and 8, with the following results:—
January 6 8 4**0°35 4**0°27In the month of January the lamps used for illuminating the field of view were removed from their original supports on the instrument and set up in sockets on the east and west walls of the room, in order to minimise their heating effect on the instrument. One end of the horizontal axis was fitted with a lens to collect sufficient rays for illuminating the threads.
16.
The thread intervals were re-determined on April 28 and May.
On August 18 a ruled glass scale was substituted for the spider threads, which are unsuited to the large variations of humidity experienced in Hongkong. It was found however that the lines on the glass were too fine, being almost invisible in certain lights.