284
mark erected in 1884. No measurable deviation of this mark from the true meridian has yet been detected. Mostly stars of southern declination, whose right-ascension is not very accurately known, have been observed, and it is intended when 20000 transits are available, say in five years from now-to form a catalogue of right-ascensions of about 2000 stars, so distributed that when the sky clears for only a couple of minutes a satisfactory determination of the time can be obtained. This is of great importance especially early in the year, when the sky is generally clouded here.
12. But with this view it is absolutely necessary that a fixed transit-circle be added to the equip- ment of this Observatory, the same as in other observatories. Such comparatively smaller centres of shipping as Madras and Perth (West Australia) have observatories supplied with fixed transit-circles, whereas the enormous shipping calling at Hongkong depends for its time and position and con- sequently safe navigation after leaving this port upon observations made with a small semi-portable instrument I have already submitted to the Government that this defect ought to be remedied. A transit-circle is not only needed for determining time and longitudo, but serves also to lay down geodetic bearings, latitude, right-ascension and declination. It can be used for observing earthquakes and would enable me to run a level right across the harbour, and otherwise contribute information required in survey work, which would be not only important at the present time but likely to be more and more useful in the future.
13. The sidereal standard clock was stopped on October the 7th in order to lessen the pressure of the electric contact springs on the teeth of the wheel attached to the arbor carrying the seconds' hand, the clock having previously tripped. The clock tripped again on the 30th October, the 18th November, and on the 1st December. After this the electric connections and the chronograph were overhauled. On November the 30th the rate was altered by adding to the pendulum a weight nearly equivalent to one second.-On the 19th August the cord of the standard incantime clock broke. Its driving weight is very heavy. On August the 22nd this clock was cleaned.
14. The errors of the time-ball are given in Table II. There were no failures in 1898. The ball is not dropped on Government holidays, and on March 6 it was not hoisted because a native computer did not attend to hoist it. On July 28th and August 17th it was not hoisted on account of strong E gales. It was dropped successfully 351 times in 1898. The probable error was in January 012, in February±0.31, in March ±0.12, in April ± 0.12, in May±0.11, in June ± 0.10, in July 0.14, in August 0.12, in September±0.17, in October± 0.16, in November ±0.10, in December ± 0.13.
Date.
Table II.
Errors of Time-Ball in 1898.
means too late.
+ means too early.
Jan.
Feb. March. April,
May. June. July. August.
Sept.
Oct. Nov.
Dec.
1
0.1
0.1
2
0.1
0.1
-0,2
0.1
0.1
4
-0.8
0.1
0.1
0.4
+0.3
0.1
0.4
+0.2
-0.2 +0.3
0.1
3333333
0.1
+0.5
+0.2
0.1
0.1
0.1
0.1
+0.3
+0.2
0.1
0.1
0.1
0.1
0.1
0.1
0.1
+0.2
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
+0.2
-0.2
0.1
+0.2
0.1
0.1
0.1
0.1
0.1
+0.4
-0.2
-0.2
-0.3
0.1
0.1
0.1
0.1
+0.3
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
+0.2
0.1
0.1
0.1
0.1
+0.2
0.1
0.1
0.1
0.1
0.1
+0.2
+0.3
0.1
0.1
0.1
+0.4
+0.2 +0.2
0.1
0.1
0.1
0.1
0.1
+0.5
0.1
0.1
10
0.1
0.1
+0.2
:
0.1
0.1
0.1
0.1
+0.5
01
0.1
0.1
0.1
+0.2
0.1
0.1
0.1
0.1
0.1
+0.6
0.1
0.1
12
0.1
0.1
0.1
0.7
0.1
0.1
0.1
0.1
+0.3
+0.4
0.1
0.1
13
0.1
-0.3
0,1
0,1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
14
0.1
+0.4
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
15
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
16
0.1 +0.3
+0.2
0.1
0.1
0.1
-0.3
0.1
0.1
0.1
0.1
17
0.1
+0.4
0.1
0.1
0.1
0.1
-0.3
0.1
+0.3
-0.2
18
0.1 +0.5
0.1
0.1
19
0.1 +0.7
0.1
0.1
20 -0.2 +0.6
0.1
0.1
21
0.1
+0.9
0.1
0.1
22
+1.0
+0.2
0.1
23
0.1
+1.1
0.4
0.1
24
0.1
+1.2
0.1
0,1
25
0.1
0.1
0.1
0.1
26
0.1
0.1
0.1
0.1
27
0.1
0.1
+0.2 +0.2
28
0.1
0.1
0.1 +0.3
29
0.1
0.1 +0.3
-0.2
30
0.1
0.1 +0.4
31
0.2
-0.2
333333:38338 13
0.1
-0.2
0.1
-02
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
+0.2
--0.2
0.1
+0.4
0.1
0.1
0.1
0.1
0.1
+0.3
0.1
0.1
0.1
0.1
-02 +0.2
0.1
0.1
+0.2
+0.2
-0.3
0.1
0.1
0.1
+0.2
+0.2
0.1
0.1
0.1
0.1
0.1
+0.3
0.1
-0.2
0.1
-0.2
0.1 +0.2
0.1
-0.3
+0.2
0.1
+0.2
0.1
0.1
-0.4
0.1
01
0.1
0.1
0.1
-0.4 +0.2
0.1
0.1 +0.3
0.1
-0.4 +0.4
0.1
0.1
+0.3
0.1
-0.4 +0.2
0.1
0.1
***
+0.3
-0.2
0.1
:
333388888888:12958