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THE HONGKONG GOVERNMENT GAZETTE, 3RD SEPTEMBER, 1881. 807
part originate in a region the centre of which is situated about a thousand miles (in round numbers) to the south and east of the Philippines. Of those which take Luzon in their course, some make for Hainan and the Gulf of Tonquin. Others pursue a more northerly direction, towards Formosa and Japan. Hongkong itself occupies a position which is comparatively exempt from typhoons, the great majority of these storms passing either to the east or south of the island. As is shown in an able monograph lately published by the Director of the Zi Ka Wei observatory, near Shanghai, out of thirteen typhoons which traversed the South China sea last year, two only passed at all near to Hong- kong, and of these the centre-tracks were at a sufficiently safe distance. Nevertheless, it is hardly possible to overstate the value of Manila as a warning station for vessels about to leave Hongkong for southern, eastern or northern ports, or vessels approaching it from those places. Means should there- fore be provided for enabling the Director of the Hongkong Observatory to be placed, whenever ne- cessary, in prompt communication by telegraph with Manila, Amoy, Shanghai, Saigon and Singapore, as well as with the south of Japan. A system of daily telegraphic weather exchanges with the chief ports should also be organized as soon as possible. For these purposes, it will be neces- sary to connect the Observatory with the existing telegraph line which crosses the harbour from Kau-lung Dock to Whitfield Police Station. The Observatory may thus be made to fulfil the useful purpose of a Weather Intelligence Office in times of danger for the whole neighbouring region; while, from the daily exchanges, ships' logs, and trustworthy private observations, a large body of facts relating to typhoons and the monsoons may be gradually amassed.
It is most unfortunate that the south part of Formosa is not as yet provided with telegraphic means of communication. This is a cardinal point in the chain of surrounding stations, and, until it is brought into telegraphic connexion with the rest, our system of weather intelligence cannot be made as perfect as might be desired. The exclusion of Hainan in this respect is also to be regretted. For purposes of warning to vessels in Hongkong harbour, a signal-mast should be erected near the Time-Ball at Kau-lung, and a code of signals established and given the fullest publication. These signals might be repeated on the existing mast at the Harbour Office.
When the scientific establishment at Kau-lung has been fairly started, it will probably be considered needless to keep up all of the meteorological stations now existing in different parts of the Colony. I certainly think that the stations at the Harbour Office, Stone Cutters' Island and the Hospital might very well be abolished. But I would recommend that those at Victoria Peak and Cape d'Aguilar be retained, as they are points at which observations, especially those of the barometer and the wind, will always be of value; and I suggest that both places be supplied with an anemometer, in order that the wind may be observed more accurately than is possible at present, care being taken to get instruments of superior strength.
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III.-Terrestrial Magnetism.
Although the character of the rocks and soil of Hongkong and Kau-lung is not the most favourable that could be chosen for magnetic research, yet the position of the Colony on the magnetic chart, and with respect to other places where observatories are already established, leaves no room to doubt that well-conducted observations of this class will be of great value to the science. These will com- prise observations for determining the Absolute Values of the elements of the Earth's magnetic force,- namely, its Declination, Inclination and Intensity--as well as those for ascertaining the periodic, secular and irregular Variations which the elements undergo, and the laws of which still await complete theoretical explanation. The former class of determinations,-i. e., those of Absolute values-are pretty certain to be more or less prejudicially affected by local attraction proceeding from the granitic rocks and soil; but the Variations, which form by far the more important object of research, can be deduced just as well in the presence as in the absence of local attraction.
The instruments with which Dr. DE LA RUE proposes to equip the magnetic branch are,
A set of photographic self-registering Magnetic instruments, of the Kew pattern, with
accessories, &c.;
A Unifilar Magnetometer;
A Dip-Circle, with four needles
all of which, as well as the Meteorological instruments, will be verified at Kew before they are sent out. Their total cost is estimated at £424.
The Photographic instruments will comprise three Magnetometers, for continuous registration of the changes in the declination and the horizontal and vertical forces by means of a central recording apparatus, driven by clockwork and carrying the photographic papers-the whole constituting, with certain accessories, a complete Magnetograph. They will exhibit the periodic variations, as well as those mysterious phenomena of simultaneous disturbance extending over the entire earth's surface, and called magnetic storms, which are amongst the most extraordinary in the whole range * This however, so far as it concerns Cape d'Aguilar, must depend upon whether good observations of the wind can be obtained at or near to the light-house, a point which may be easily ascertained.