640 SUPPLEMENT TO THE HONGKONG GOVT GAZETTE OF 18TH JULY, 1885.
as Typhoons I and XIV. After recurving, they generally cross Japan or the Sea of Japan, or strike the coast of Corea. These paths are explained simply according to CLEMENT LEY's law:--while SW of the high pressure in the North Pacific they pass NWestward, when arrived W of it, they pass Northward, and when arrived NW of it, they pass NEastward, and no doubt subsequently Eastward, if their energy is not expended, before they are N of the area. They are common about the middle of the typhoon season, and their life is on an average 7 days.
Typhoons of the third class are possibly the most common, but it appears that they are less frequently encountered, and therefore perhaps often escape observation. They pass E of Formosa moving Northward. After recurving they frequently skirt the Southern Coast of Japan, or enter and traverse the Sea of Japan, as Typhoons VI, X, XI and XIII. A typhoon of this class frequently follows after one of the second class. When the latter has recurved, the former proceeds Northward. This is explained by the circumstance, that the effective low-pressure area in Asia,--the preceding typhoon, is then in fact considerably E of its normal position. It is also well known, that depressions are attracted towards places, which have just been traversed by a depression. Their life is of uncer- tain duration.
Typhoons of the fourth class pass S of Luzon, moving apparently Westward or first Westward, and then SWestward. They are perhaps not uncommon, but are really situated outside the field of our investigations. They appear in some respects to differ from typhoons of the other classes, and I believe, that they are accompanied by thunderstorms. They are situated in so low a latitude, that the effect of the earth's rotation is much less than in case of other typhoons, and as they appear to quickly approach the equatorial belt, they form perhaps a link between typhoons proper, and the atmospheric disturbances in that neighbourhood, which are unconnected with rotating winds.--Their life appears to be between one and two days.
The average velocity of the typhoons of 1884 was as follows:--E of Luzon: 7 nautical miles an hour. In the China Sea between 12° and 18° N: 6 miles an hour. In the China Sea between Hong- kong, Luzon and Southern Formosa: 11 miles an hour. About Hainan: 13 miles an hour. E of Formosa: 10 miles an hour. In the Formosa Straits: 12 miles an hour. In Kwangtung, Fokien and Kiangsi: 10 miles an hour. About Shanghai: 12 miles an hour. In Northern China: 23 miles an hour. About Japan: 19 miles an hour. In the Sea of Japan: 30 miles an hour.
Hongkong Observatory, 16th July, 1885.
W. DOBERCK, Government Astronomer.
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