F 13
In the following table is given the excess of the observed over the computed error after cloudy periods during 1921 :-
Date 1921.
February March April May June July August September November December
17, 7, 1, 30, 21, 6, 29, 21 6, 21, 2,
* Interval without observations.
2 days 7 [ 2 4 7 +
,,,,,,,,, !
+, 25: 3 3+ 3 27
Excess of observed over computed error.
secs.
0*23 + 0.17 -1.99 +0°52
0*22 + 0·04 + 0.43
- 0'57 + 1.10
+ 0'17 + 0.63 1.03
0'32
The Dent Mean Time clock (No. 39740) was used throughout the year for dropping the Time Ball, maintaining the electric time service in the Observatory, and sending hourly signals to the Railway, the Post Office, the Telephone Co., and the Eastern Extension Telegraph Co. The clock is corrected daily before 10 a.m. and before 4 p.m. by the electric regulating apparatus. Its daily rate is kept below 0.5 sec. by the addition or removal of weights from the pendulum.
Chronometer Dent No. 10917 is on loan to the Cape d'Aguilar Wireless Station, and chronometer Dent No. 39946 to the Peak Signal Station.
Batteries, Power Supply, &c.---The necessary current for the Time Service has been supplied by accumulator batteries, charged as found necessary from the alternating mains of the China Light & Power Co., Ld., by a rotary converter.
IX.- MISCELLANEOUS.
Seismograph Installation.—One component of the Milne-Shaw Seismograph was received on September 28 and set up on a temporary mounting the next day.
The minute signal sent by the mean time clock for time scaling the records was found to be too short to make a perceptible break in the photographic record, a dash pot was therefore fitted to the eclipsing shutter. Its final form, as constructed by Mr. Evans, is similar in action to the piston in an oil force pump. It allows a sharp forward movement of the shutter, with a slow backward movement. The duration of the eclipse is regulated by it.
!
F 13
In the following table is given the excess of the observed over the computed error after cloudy periods during 1921 :-
Date 1921.
February March April
17,
7.
I,
30,
*
21,
6.
May
June
July
29.
21
August
Interval without observations.
2 days 7
[ 2
4
7
+
,,,,,,,,,
!
+,
25:
3
3+
3
27
September 6,
November 21,
December 2,
י
>>
Excess of observed over computed error.
secs.
0*23
+ 0.17 - 199 +0°52
0*22
+ 0·04 + 043
- 0'57
+ XIO
+
0'17 + 0.63 10:03
0'32
year
The Dent Mean Time clock (No. 39740) was used throughout the for dropping the Time Ball, maintaining the electric time service in the Observatory, and sending hourly signals to the Railway, the Post Office, the Telephone Co., and the Eastern Extension Telegraph Co. The clock is corrected daily before 10 a.m. and before. 4 p.m. by the electric regulating apparatus. Its daily rate is kept below 05 sec. by the addition or removal of weights from the pendulum.
Chronometer Dent No. 10917 is on loan to the Cape d'Aguilar Wireless Station, and chronometer Dent No. 39946 to the Peak Signal Station.
Batteries, Power Supply, &c.---The necessary current for the Time Service has been supplied by accumulator batteries, charged as found necessary from the alternating mains of the China Light & Power Co., Ld., by a rotary converter.
IX.- MISCELLANEOUS.
Seismograph Installation.—One component of the Milne-Shaw Seismograph was received on September 28 and set up on a temporary mouuting the next day.
The minute signal sent by the mean time clock for time scaling the records was found to be too short to make a perceptible break in the photographic record, a dash pot was therefore fitted to the eclipsing shutter. Its final form, as constructed by Mr. Evans, is similar in action to the piston in an oil force pump. allows a sharp forward movement of the shutter, with a slow backward movement. The duration of the eclipse is regulated by
it
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