F 11
Comparison of Barometers.-During the year about 350 comparisons of ships' barometers have been made by means of observations taken when in harbour, and several direct comparisons of barometers for shipmasters and various persons in the Colony have been made at the Observatory.
VII. MAGNETIC OBSERVATIONS.
Absolute determinations of magnetic horizontal force and declination were made in the old magnetic hut, near the middle of each month, with a Kew pattern magnetometer, Elliott No. 55, and of dip with a Kew pattern dip circle, Dover No. 71; four dip needles being used in rotation. A complete determination of horizontal force consists of one set of vibrations taken between two sets of deflections.
The mean values of the Magnetic elements for the years 1917 and 1918 were as follows:-
1917 1918 Declination (west) 0° 16' 16" 0° 17' 57" Dip (north) 30° 50' 22" 30° 48' 48" Horizontal Force (C. G. S. unit) 0.37163 0.37164 Vertical Force (C. G. S. unit) 0.22188 0.22159 Total Force (C. G. S. unit) 0.43282 0.43269VIII.-TIME SERVICE.
Time Ball.-The Time Ball on the Signal Hill, Kowloon, is dropped daily at 13h., Hongkong Standard Time (5 a.m of Greenwich Time). The ball is also dropped at any other hour in case of necessity. No applications for a supplementary signal were made in 1918.
The ball was dropped successfully 353 times. There were 11 failures:- On January 14th it failed from no ascertainable cause, on March 19th, July 3rd and 4th owing to electrical defects, and on October 6 and 7 owing to trouble with the lock. On October 8 the lock was removed for repair and the spare lock substituted. This lock is known to be unsatisfactory, and it failed to drop the ball on December 4, 12, 16, 23 and 24. On December 25 the normal lock was again brought into use. The ball was dropped at 14h. on January 14th, 15h. on July 3, October 7, December 12, and December 16, and at 16h. on December 24. The ball was not raised on August 15th, on account of high wind.
The ball fell with an error of 0s.3 or less on 324 occasions, and with an error of 0s.4 or 0s.5 on 23 occasions. Errors of 0s.6 and 0s.8 occurred once, and of 0s.5.7 and 0s.9 twice.
F 11
-
Comparison of Barometers.-During the year about 350 comparisons of ships' barometer have been made by means of observations taken when in harbour, and several direct comparisons of barometers for shipmasters and various persons in the Colony have been made at the Observatory.
VII. MAGNETIC OBSERVATIONS.
Absolute determinatious of magnetic horizontal force and declination were made in the old magnetic hut, near the middle of each month, with a Kew pattern magnetometer, Elliott No. 55, and of dip with a Kew pattern dip circle, Dover No. 71; four dip needles being used in rotation. A complete determination of hori- zontal force consists of one set of vibrations taken between two sets of deflections.
The mean values of the Magnetic elements for the years 1917 and 1918 were as follows:-
Declination (west).
Dip (north)......................
>
1917
1918
O
/
//
0 16 16
0 17 57
30 50 22
30 48
48 19
0-37163 0.22188
0-37164
0-22159
0-43282
0.43269
...
Horizontal Force (C. G. S. unit) Vertical Force (C. G. S. unit) Total Force (C. G. S. unit)
VIII.-TIME SERVICE.
Time Ball.-The Time Ball on the Signal Hill, Kowloon, is dropped daily at 13h., Hongkong Standard Time (5 a.m of Green- wich Time). The ball in also dropped at any other hour in case of necessity. No applications for a supplementary signal were made in 1918.
The ball was dropped successfully 353 times. There were 11 failures:- On January 14th it failed from no ascertainable cause, on March 19th, July 3rd and 4th owing to electrical defects, and on October 6 and 7 owing to trouble with the lock. On October 8 the lock was removed for repair and the spare lock substituted. This lock is known to be unsatisfactory, and it failed to drop the ball on December 4, 12, 16, 23 and 24. On December 25 the normal lock was again brought into use. The ball was dropped at 14h. on January 14th, 15h. on July 3, October 7, December 12, and December 16, and at 16h. on December 24. The ball was not raised on August 15th, on account of high wind.
The ball fell with an error of 03 or less on 324 occasions, and with an error of 04 or 05 on 23 occasions. Errors of 06 and 08 occurred once, and of 05-7 and 0.9 twice.
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