1
•
THE HONGKONG GOVERNMENT GAZETTE, 29TH JANUARY, 1887.
85
The probable errors of the signal in the different months of 1886 (with the average percentage of clouded sky added in parenthesis) were as follows:
January 0.27 (65), February 0.34 (96), March 0.36 (92), April 0.46 (82), May 0.34 (71), June 0.22 (76), July 0.14 (76), August 0.16 (71), September 0.20 (51), October 0.20 (48), No- vember 0.18 (35), December 0.13 (31).—The mean of the probable errors was 0.19 in 1885 and 0.925 in 1886, and the probable error of the signal during the two past years was therefore about a fifth of a second.
As stated in the time-ball notice published in the Government Gazette on the 10th January 1885, the ball is not dropped on Sundays or on Government Holidays. On the 30th March it failed at 1 p (clock failing to make contact) but was dropped at 2 p. On the 15th July it failed at 1 p (the tele- graph wires being entangled) but was dropped at 2 p. On the 16th, 17th and 19th the ball could not be dropped as the wires were entangled. On the 7th September it failed owing to defective telegraphic connection and also at Ip on the 8th, but it was dropped by hand at 2 p on the latter date. The ball was dropped by hand from the 9th September till the 2nd November. From the 3rd till the 11th November the signal was not given owing to illness among the staff. Since the 12th November the ball was dropped without intermission by aid of excessive battery-power introduced with the sanction of the Governor.-It is seen, that the time-ball apparatus failed to act only once in 1886, that the telegraphic connection was the cause of failure on 15 days and that the ball was dropped by hand on 47 days. I reported in July the necessity for a new line and this has been approved by His Excellency.
MICROMETRIC MEASURES OF JUPITER.
Diameter.
Breadth.
Length.
Obs.-Calc.
Epoch.
Pos.
m
n M.P.
Equ. Pol
Belt Spot Spot Pos. Equ.
Pol..
1879 August
• ""
"
"
29,... 335.65+0°.17 4 November 24,... 336 .53 .42 5
29,..
.05 2
200
-0°.20 .07
336 .30
2".42
11.87
.09
December 19,.
336 .65
.32
"}
+ .65
1880 September 12,.
336 .23
.10 4
.25
99
27,... 335 .25
.30 4
October
17
21,... 834.98
.33
"
"
29
23,... 335.35
.00 3
""
""
28,... 335.13
""
November 3,... 334 .47
"
December 1,... 336.05
""
""
3,... 334.73
.17 4 .13 4 .23 4 .04 4
""
50.17 47".25 49.61 46 .84 48 .99 46 .24 49.35 46 .05
3 .39 9.13 3.62 8.19 | 3 .35
15 .55 14 .89 15 .79
.49
.39
8.48 8.78
3 .59
:
+14.13 +1".29 .00 +0.68 +1.00 .15 +0.46
+0.73
.75
"
+1.39 +1.03
9 4
45,25 42 .28
7.79
.97
+0.97
+0.45
44 .69 42 .38
8.86
.35
""
+0.71 +0.87
22
6,... 335 .37
.17 4
43.54 42 .20 8.88
19
+0.30
1882 October
26,... 359.93
.50 4
43.70 41 .09
""
-0.01 +1.09
-1.57 +0.61 +0.46
4
December
"
1883 January
7,... 359.30 .30 4 6,... 356.95 .30
400
47 .26 44.43
4
200
47.63 44 .63
•
"
"
8,... 354.45 .70 4 1885 December 27,.. 23.60 0.91 7 28,... 25.84 1.34 8
+
200
47 .41 45 .24
110
"
-0.54 +0.14 +0.29
-1.06
-3 .45
+1.12 +1.05
+1.03
+1.78
-1 .64 +0.62
...
1886 April
7.... 24.40 0.28 4
-1.00
""
...
The distance of the great ruddy spot from the nearest edge of the belt was measured on October 21st, 1880, as 3".63, and on October 23rd, as 37.53. The satellites were measured on November 3rd, 1880, as follows: I 1".00, II 1".18, IV 1".30.
The first column in the table exhibits the epoch, the second the angle of position of the polar axis, the third the average déviation of the single measures from the mean (from which the probable error is easily obtained), the fourth the number of pointings, the fifth the magnifying power, the sixth the apparent diameter of the equator, the seventh the diameter vertical to the latter, the eighth and ninth the breadth of the equatorial belts and the great spot, the tenth the length of the latter when on the central meridian. The eleventh, twelvth and thirteenth columns exhibit the differences between the observed values and those calculated by Marth, in which comparison the phase has been taken into account as usual.
From the differences exhibited in the eleventh column the following normal values of the position angle were obtained: I 1880, July 3rd, 335°.95. II 1882, December 14th, 357°.96. III 1886, February 7th, 24°.56. From I and III the right ascension and declination of Jupiter's North-pole were determined as follows: A.R. 275°4', Decl. +65°26′ or Long. 330°25′, Lat. +$7°34′. Referred to Leverrier's orbit of Jupiter the longitude of the node and the obliquity of the Jovian ecliptic came out as follows: N. 290°31′, ΰ39′. The difference between the position angle II and that calculated from these elements is +2°.94.
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