92
6. The amount of success attached to the firing of the typhoon gun to indicate local gales has been determined according to the method adopted at meteorological offices at home. According to this method of counting, the storm-signal is justified if followed by a gale of force 8 and upwards within 48 hours at a place near sea-level within 50 miles of the place where the signal is hoisted. It is a failure because "too late," if it blows a strong gale (force 9) before the signal is hoisted. According to this way of counting, a failure has to be recorded every time the gun is not fired during the winter for a "Norther," although we do not presume to forecast those, as that cannot be done till information is available from the interior and northern ports, e.g., from Hankow and Chefoo, from which ports no telegrams have as yet reached the Observatory.
7. The typhoon gun has been fired 27 times one round, since the Observatory was started on the 1st January, 1884, i.e., during the past 13 years. During the same period it has 30 times blown a gale of force 8 and upwards: Once in February (norther), once in June (typhoon), 5 times in July (typhoons), 3 times in August (typhoons), 11 times in September (typhoons), 7 times in October (typhoons), and twice in December (northers).
27
8. The following table gives an account of all the gales that have passed over the Colony during the past 13 years and the warnings given by the typhoon gun. This shows 75% of success counting all the gales and all the times the gun was fired, or 83 % of success if the
"Northers be left out of the account. This compares favourably with the percentage of success in the British Isles, 58 % only of which are justified by subsequent gales of force 8 and upwards (mean of the 10 years 1884-93 inclusive) This leaves out of account the fact that in those isolated instances, where the gun was not fired, warning was given by notices issued and, of late years, by lanterns hoisted.-During the first eight years the gun was fired when the wind blew 37 miles per hour, on an average, while during the past four years it was fired when the wind blew only 27 miles per hour on an average. This shows an improvement with the increase of staff that took place in the meantime, and with the increase in the number of telegraphic reporting stations. Detailed particulars concerning every typhoon are published in the "Observations and Researches."
Table I.
Whe-
ther
Wind velocity
Highest wind velo-
Interval between gun-fire and
at the
Success
the gun
When the
When it
Obser-
Was fired
gun was fired.
blew hardest.
city at Observa-
or
Remarks.
vatory
when
or not.
fired.
tory or Gap Rock.
begining of
strong
gale.
highest wind velocity.
Failure.
m. p. h.
m. p.
h.
hours.
hours.
No.
1884 July 29th 8 p.
ગ
55
Failure.
Yes.
1884 Aug. 21st
25
1884 Aug. 21st
25
Failure.
9.45 p.
9.45 p.
At noon on the 28th typhoon notified as approaching coast not far from Hongkong.
No gale: Colony in left-hand semi-circle of typhoon (centre within 180 miles).
Yes. 1884 Sept. 10th
29
5.45 a.
1884 Sept. 10th midt.
89
13.2
18.2
Success.
Yes.
1885 Aug. 17th
42
1885 Aug. 17th
53
2.5
2.5
Success.
12.30 p.
3 p.
No.
1886 Dec. 7th
54
Failure.
(Norther).
5 2.
Yes. 1887 July 20th
42
1887 July 20th
50
11.5
11,5
Success.
4.30 a.
4 p.
Yes. 1887 Sept. 11th
31
1887 Sept. 11th
51
3.9
3.9
Success.
7.05 p.
11 p.
Yes. 1887 Sept. 17th
40
1887 Sept. 17th
69
2.2
8.2
Success.
Yes.
8.50 a.
1887 Sept. 20th
5 p.
•
39
1887 Sept. 21st
56
12.9
15.9
Success.
10.05 p.
2 p.
Yes. 1887 Sept. 25th
34
1887 Sept. 26th
55
22.5
22.5
Success.
6.30 a.
ja.
Yes. 1888 Sept. 28th
7.55 a.
35
1888 Sept. 28th 10 p.
50
14.1
14.1
Success.
No.
1889 Feb. 10th 1 a.
53
Failure.
(Norther).