236
Socotra, So-shu Maru, Spezia, Stentor, Suevia, Suisang, Sumatra, Sunda, Sungkiang, Taifu, Taikosan Maru, Taishan, Taiwan, Taiyuan, Tango Maru, Tartar, Tean, Telemachus, Telena, Terrible (H. M. S.), Tinhow, Tjibodas, Tjilatjap, Tjiliwong, Tjimahi, Tjipanas, Totomi Maru, Tranquebar, Tremont, Trieste, Tsinan, Twickenham, Tydeus, Umballa, Uniform, Venetia, Verona, Victoria, Volute, Wabafuto Maru, Waihora, Wakamatsu Maru, Waterwitch (H. M. S.), Willehad, Wisconsin (U. S. S.), Woolwich, Wongkoi, Wosang, Yangmoo, Yawata Maru, Yiksang, Yochow, Yoshin Maru, Zafiro, Zaida, Zibenghla, Zoroaster.
17. The entry of observations made at sea in degree squares for the area between 9° South and 45° North Latitude, and between the longitude of Singapore and 180° East of Greenwich, has been continued by Miss Doberck and 309,284 in all have now been entered (Table II).
18. As stated in the "Instructions for making Meteorological Observations, etc.", meteorological instruments forwarded by observers, who regularly send their Registers to the Observatory, are verified here free of cost. During the past year one barometer, one aneroid and six thermometers were verified. In addition several hundred barometers and aneroids on board ship were compared with our standard.
19. Mr. FIGG has made 201 sets of observations of dew-point with Alluard's apparatus, simultaneous observations being taken with rotating dry and damp thermometers. The results will be used in the improvements of hygrometric tables. It is expected that there will soon be a chance of having these observations continued in England, which is of import- ance for the purpose of having them extended through a longer range of temperature.
20. In 1906 the number of transits observed was 542. The axis of the transit instru- ment was levelled 276 times and the azimuth and collimation errors, which are less liable to variation were determined 39 times by aid of the meridian mark. Since the return of Mr. PLUMMER from leave of absence on the 24th February these observations, which were previously made by Mr. FIGG, have all been made by him. No alterations have been made in any of the standard clocks during the year and the going of all has been fairly satisfactory.
The errors of the Time-ball are given in Table III. The ball is not dropped on Sundays nor on Government holidays. There were two failures during 1906. On the 26th July the ball was prevented from falling intentionally because a flash of lightning occurring about 80 seconds before 1 p.m. had reversed the magnetism of the galvanometer and it was impos- sible to judge whether any other damage had been done. On the 2nd June the ball was also intentionally prevented from falling but that was owing to a mistake on the part of the observer in charge. On twelve other occasions the ball was not hoisted, viz., on the 18th and 29th September in consequence of typhoons, on the 10th April in consequence of a thunder- storm and on the 9th April, the 22nd and 23rd May, and from the 19th to 25th September, owing to interruption of the line and repairs not having been effected. The ball was dropped 287 times in 1906. The probable error was in January ±0. 14, in February ± 0. 15, in March±0.39, in April ± 0. 16, in May ±0. 15, in June +0. 18, in July +0. 17, in August 0.12, in September ±0. 23, in October ±0. 13, in November ±0. 14, in December ±0.10.
21. A new site for a time-ball tower has been selected on Signal Hill near the meridian of the transit instrument. The plans for the new tower have been approved and its con- struction is proceeding. It is much taller and roomier than the old tower and other improve- ments have been introduced based on twenty-three years' experience.
22. The cisterns of the barograph and standard barometers are placed 109 feet above M.S.L. The bulbs of the thermometers are rotated 108 feet above M.S.L. and 4 feet above the grass. The solar radiation thermometer is placed at the same height. The rim of the raingauge is 105 feet above M.S.L. and 21 inches above the ground.
23. An eight-inch raingauge was fixed by me in the Police compound at Taipo about ten miles to the North of this Observatory. The amount of rain in inches measured was as follows: Jan. 1.10, Feb. 3.80, Mar. 2.91, April 14.27, May 13.14, June 7.16, July 11.43, Aug. 6.75, Sept. 30.88, Oct. 2.01, Nov. 0.06, Dec. 0.71. The total for the year 1906 was 94.22 or about a fifth more than at this Observatory. A new Halliwell raingauge has been worked throughout the year at the Observatory, and has been of great assistance in measuring heavy
rain.