682276-1881-Observatory-Hongkong- — Page 8

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THE HONGKONG GOVERNMENT GAZETTE, 3RD SEPTEMBER, 1881.

II. Meteorology.

The proposal to establish a meteorological branch of the observatory, under skilled management In the first place, and supplied with the best modern apparatus, commands approval for two reasons. as Dr. DE LA RUE has indicated, such an institution will furnish the science with valuable and much needed data, from a locality well suited for the observation and collection of facts appertaining to certain phenomena of special interest. Secondly, it cannot fail to have a direct and practical value, as being the means of affording security, by its predictions and weather warnings, to life and property, in seas navigated by vast numbers of native and foreign vessels, but subject during four or five months of the year to rotatory storms of appalling violence and danger.

Its operations, like its purpose, will be twofold. There will be, to begin with, the systematic observation and record of the ordinary phenomena of pressure, temperature, humidity, rain, sunshine, wind and hydrometeors, such as are usual in observatories of the first order; together also with observations of atmospheric electricity.

So lately as last February, Dr. WARREN DE LA RUE furnished the Colonial Office with a list of the instruments necessary for these purposes in a first-class meteorological observatory. The list comprises a Barograph, a Thermograph, an Anemograph, a Rain-gauge, a Sunshine Recorder, and an Electrograph; together costing about £397.

Of these, the Barograph, or self-recording barometer, will be accommodated in the Magnetic basement, to be presently described.

For the Thermograph-i. e., self-registering (photographic) dry and wet bulb thermometers—a special hut and shed will have to be put up in the grounds of the observatory. This may, however, be left until the instruments arrive. The Thermograph, it will be observed, does away with the. necessity for maximum and minimum thermometers, as the changes of temperature are recorded unceasingly.

The Anemograph, or self-recording Anemometer, is an instrument the best and newest forms of which are constructed to register continuously the direction, pressure and velocity of the wind. We are not told by Dr. DE LA RUE what kind will be sent. A small turret, to carry the vane, &c., for the instrument, of whatever pattern, may be erected centrally over the front verandah roof of the main building, and the spindle be carried through the roof to the registering apparatus placed in a small chamber or compartment on the upper verandah, as shown in the drawing.. The turret must be provided with a lightning conductor.

The Rain-gauge, to judge from the high price (£60) set against it in the list, is doubtless a self- recording instrument, or pluviograph. At Greenwich, an Osler's Anemometer and Rain-gauge form a This instrument joint apparatus, by which wind and rain are registered on the same sheet of paper. needs no special provision beforehand.

The Sunshine Recorder is a contrivance for marking and measuring the duration of sunshine. The instrument in use at Greenwich consists of a solid glass ball four inches in diameter, supported in a hollow hemispherical bowl of three inches' radius, the two surfaces being separated from one another by a space of an inch. The rim of the bowl is marked like a sundial, and the interior surface is lined with a strip of prepared mill-board. Whenever the sun shines out, its rays, brought to a focus by the glass ball, burn a mark on this strip. The intervals and interruptions of sunshine are thus recorded. This instrument may be set up on the roof of the main building, for which purpose no special preparations are needed.

The Electrograph of Dr. DE LA RUES' list, though not described, is doubtless a THOMSON'S Quadrant Electrometer, fitted for photographic self-registration. It has been shown that I have provided a small room for it on the ground floor of the main building; the window of which can be darkened to the extent required. The collector for this instrument may be attached to a small mast on the roof, above the room; and the wire or rod be carried thence to the instrument, the pier for which should be capped with a slate or marble slab.

The whole of the above, it will be noticed, are autographic instruments, and need only occasional attention, for changing the record-sheets, pointing the pencils, &c. The labour of observation is thus reduced to a minimum.

The second branch of work appertaining to the Meteorological Department will be the observation and collection as far as possible of facts and phenomena relating to typhoons, both for the protection of marine interests and for the purpose of contributing bit by bit to our knowledge of a subject at present but little understood. It will include also the giving attention to the phenomena

of the monsoons,

For weather warnings, the telegraphic cables connecting this port with others on the coast, and with Manila, will furnish most valuable aid. The Manila cable will be of special service in this respect. Past observations seem to show that the typhoons which sweep the Southern China sea for the most