Sessional_Paper_1898 — Page 116

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More or less persistent SW winds, at times accompanied by thunderstorms, may be expected. when the red cone pointing upwards is hoisted, and ships leaving the port are not likely to run any risk from the typhoon. Sailing vessels bound for the north should start as soon as possible so as to benefit by the southerly breezes to run through the Formosa Channel, and avoid the way round Formosa. By following the latter route a sailer, morcover, runs the risk of falling in with the next typhoon east of Formosa, particularly during the months of August and September.

A cone pointing downwards usually implies fresh E veering to SE winds in Hongkong. As such a typhoon may travel N and NE, the master of a vessel desirous of avoiding bad weather should consult the latest weather-intelligence or remain in port till the barometer rises. Then the danger is past.

When a ball is hoisted ships starting for northern, eastern, or southern ports may expect breezes from E round to S and SW. Those starting for western ports run no risk as long as the glass continues to rise. Should it ever happen to fall: heave to and, if necessary, take refuge in a typhoon anchorage such as Saint John's harbour.

Mr. FIGG has analysed his weather-forecasts for 1896 with the following results:—

The results for wind direction, force, and weather are treated separately in the first instance. The forecast wind direction is considered successful if the wind at Gap Rock blows the greater part of the 24 hours from a direction that does not differ more than 45° from the forecast (93 % were successful). Forecast wind force: "light," is successful if the mean force registered at Gap Rock is a light breeze, or if the wind force does not reach the force of a moderate breeze; "moderate," if the meau is a moderate breeze, or if the wind force exceeds a light breeze and falls short of a strong breeze; "fresh," if the mean is a fresh breeze, or if the wind force exceeds a gentle breeze and falls short of a moderate gale; "strong" if the mean is a strong breeze, or if the wind force exceeds a moderate breeze and falls short of a fresh gale; gale," if it blows more than 10 miles per hour at Gap Rock (93% were successful).

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wet,

The weather is successful when "fine " is forecast if the mean amount of clouds is below 7-tenths of the whole sky, if sunshine or starlight prevails, and when it does not rain more than one hour out of twenty-four; when "fair, cloudy," if the amount of clouds exceeds 3-tenths and it does not rain. more than one hour; when "showery," if it rains at intervals and is fair at intervals; when " rainy' if it rains more than 4 hours (77% were successful). Counting days on which all three elements were correctly forecast as success, those when two elements were justified and one failed as "partial success," those when one element was justified and two failed as partial failure," and those when all elements failed as "total failure," we have :—

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Success 67 %, partial success 30 %, partial failure 2%, total failure 1 %.

(C

Following the method used in meteorological offices and taking the sum of total and partial success as a measure of success, and the sum of total and partial failure as a measure of failure, we find finally that :-

97% of the weather-forecasts were successful.

The amount of success attached to the firing of the typhoon gun to in licate 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 did not presume to forecast those.

The typhoon gun has been fired 27 times one round, since the Observatory was started on the 1st January, 1884, ie., during the past 13 years. During the same period it has 30 times blowu 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).

There was 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 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 in the Observatory that took place in the meantime, and with the increase in the number of telegraphic reporting stations. Detailed particulars concerning every typhoon that occurred during the past thirteen years and every warning issued have been published in the "Government Gazette" and in the "Observations and Researches" issued yearly from here.