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Malabar coast, the barometer on board a ship read 28 inches, whilst the barometer at Ootacamund, 100 miles distant, reduced to sea-level, stood at 30, thus showing a difference of 2 inches in 100 miles. If there had been observations at intermediate points, it is probable that steeper gradients would have been observed than at the rate of 1 inch in 29 miles.

548. Veering of the Wind during the Storm.-At St Croix, situated in the south or left-hand side of the storm's track, the veering of the wind, as recorded by Mr Andrew Lang, who has paid much attention to these West Indian hurricanes for the last fifty years, was as follows: On the morning of 28th September the wind was N.E. (the usual trade-wind); at 4 P.M., N.; on the 29th, at 6 A.M., W.; at 10 A.M., W.S.W.; on the 30th, at 6 A.M., S.; on the 1st, at 6 A.M., S.E. It then shifted to the east, and on the afternoon of the 2d to E.N.E. Observations from other six places, or ships, on the left-hand side of the track of the storm all show that the wind veered in precisely the same way-viz., from N.E. to N., W., S., E. The ship Mexican, whose course during the storm was from 200 to 300 miles north-east of Nassau, recorded the following veerings of the wind On 1st October, at 6 A.M., E.; at 6 P.M., E.S.E.; on 2d, at 6 A.M., S.S.E.; at noon, S.; and at midnight, S.S.W. ; on the 3d, at 6 A.M., S. W.; at noon, W.S.W.; and at 6 P.M., W. Observations from other five places, or from ships, on the right-hand side of the storm's track show that the wind veered in the same direction-viz., from N.E. to E., S., W., and N. At St Croix the wind veered from N.E. by W. to S.E., and afterwards to E.N.E., or nearly round the compass; but by the ship Mexican the veerings were only from E. by S. to W., or about half the compass. In the former case the place of observation was much nearer the centre of the storm than in the latter case. Generally, the extent through which the wind veers at any place diminishes in proportion to its distance from the centre of the storm when it passes that place and at places situated just at the outside of the area swept over by the storm, the veering of

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the wind is very small. These facts regarding the veering of the wind are a simple consequence of the revolving character of the storm, and its progressive motion over that part of the earth's surface.

549. I constructed other eight synchronous charts of this storm at different points of its course, and they all agreed in the essential features portrayed on the chart, Plate VIII. I have also constructed similar charts of the storms described by Redfield and Reid, and have not found them to differ in any essential point from the Bahama hurricane of October 1866. All are revolving storms showing the wind blowing round and in upon the centre of least atmospheric pressure when the barometric depression at the centre was known; and when not, they were observed blowing round and in upon a centre presumed, from the general direction of the winds, to be that of least pressure. None of those examined showed the winds blowing directly towards the centre of least pressure; though in some instances, when observations were had from points in the immediate neighbourhood of the centre, there was a tendency in the winds to turn further round so as to approximate to the centripetal direction. None of the storms, at any hour at which they were charted, exhibited the winds whirling round the centre in perfect circles, but all were "vorticose," to use Sir John Herschel's expression-that is, they were formed of spirally in-moving currents of air.

550. At Nassau the calm at the centre of the storm lasted an hour and a half, from 7.20 to 8.50 P.M. While the vortex of the storm was passing over the harbour, Captain Chatfield remarks that the atmosphere was most oppressive, and the clouds in the zenith appeared to be revolving rapidly; there was a little lightning, but no thunder; at 7.30 the clouds in the zenith rose, and the stars appeared, while banks of clouds remained all round the horizon in heavy dense masses. These appearances which occur at the centre or "eye of the storm" are well known to sailors who have encountered tropical storms, and they illustrate well the revolving character of these storms.

551. The West Indian hurricanes occur most frequently from July to October. From Poey's 'Chronological Table of 365 West Indian and North Atlantic Hurricanes, from 1493 to 1855,' we learn that 42 occurred in July, 96 in August, 80 in September, 69 in October, and the remaining 68 were distributed over the other eight months of the year. The tracks of the more important of these storms are laid down in Dr Keith Johnston's splendid Physical Atlas.'

STORMS OF SOUTHERN ASIA.

552. Typhoons.-The name typhoon is applied to the storms which occur at certain seasons in the north of the Indian Ocean and in the Chinese Sea. As regards their form, the sudden barometric changes accompanying them, and the blowing of the winds round and in upon the centre, where the pressure generally falls to 28 inches, and even on rare occasions as low as 27 inches, they entirely resemble the West Indian hurricanes already described. The chief point of difference is in the general direction of their route. The general course of the storms of Hindostan is from a point a little to the west of the Andaman Islands to N.N.W. or towards the mouth of the Ganges, after which they ascend the valley of the Ganges or that of Brahmaputra. The typhoons of the Chinese Sea have their origin in the ocean to the east of China, especially about Formosa, Luzon, and the islands immediately to the south. They thence proceed from E.N.E. to W.S.W.; rarely from E.S.E. to W.N.W.; and scarcely ever from N. to S. or from S. to N. Thus the course generally taken by these typhoons is along the Chinese coast; and hence the coast feels the northern side of the storm, while at a distance out at sea the southern side is experienced. They occur from May to October; but it is during July, August, and September that they are most frequent. The season of the typhoons coincides, therefore, with the annual period of the monsoons. Here, then, are two great atmos

pheric currents-the S. W. monsoon, prevailing over southern Asia, and the ordinary N.E. trade-wind in the Pacific Ocean to the east-flowing side by side, but in opposite directions (see isobarometric lines for July, Plate I.) On this account, an examination of these storms from observations made in China and on the ocean and islands to the east and south of it would possess considerable interest to meteorologists, since from this peculiarity typhoons are well fitted to throw light on inquiries affecting the origin and tracks of storms.

553. STORMS OF THE INDIAN OCEAN SOUTH OF THE EQUATOR.-Through the activity and well-directed efforts of the Meteorological Society of Mauritius, the storms of the Indian Ocean have been submitted to a fuller examination than those of any other ocean on the globe. Since the formation of this Society in 1851, it has devoted a large share of its attention to the collecting of Meteorological Statistics of the Indian Ocean, and the tabulating of them in chronological order. Upwards of 500 synchronous weathercharts have been constructed under the direction of its able and energetic secretary, Charles Meldrum. I have, through his courtesy, examined a considerable number of these charts, which, if the isobarometric lines were filled in, would leave nothing to be desired. At the meeting of the British Association held in Dundee in 1867, Mr Meldrum gave an account of these storms; and it is chiefly from this paper, a copy of which he has kindly sent me, that the following facts regarding them have been taken. Of these storms there are two sorts-viz., tropical and extratropical storms.

554. Tropical Storms.-The tropical storms occur only from November to May inclusive. They originate between the parallels of 6° and 14° lats., and thence proceed in the direction of W.S.W., and afterwards, though not always, their course curves round and turns towards the S. or S. E. The winds invariably move round a central space, usually characterised by a calm, and are at the same time drawn in on all sides towards the central calm in an in-moving spiral The direction in which the winds move round the

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centre is from left to right, or with the hands of a watch, being the direction of the winds in storms of the southern hemisphere. This is the only circumstance in which the storms of the southern hemisphere essentially differ from those of the northern hemisphere. Both depend on the same cause-viz., the rotation of the earth on its axis in its effect on the winds as they pass from lower to higher latitudes, or vice versa. The diameter of the storm is generally from 1000 to 1500 miles; and the progressive motion is at the rate of 1 to 20 miles an hour-the general rate being from 4 to 7 miles an hour. It lasts from a few hours to ten days, and is accompanied with torrents of rain, and, in its northern half, often with lightning.

555. These storms are invariably generated between the N.W. monsoon and the S.E. trade-wind, or they originate in the region of calms which lies between the two trade-winds prevailing in the Indian Ocean from November to May. As already stated, Mr Meldrum has shown that the region of calms at this season does not lie parallel to the equator, but slants from Tamatave, in Madagascar, to the west of Samatra. If the chart (Plate II.) giving the isobarometric curves for January be examined, it will be seen that the N.W. monsoon, which prevails in the northern part of the Indian Ocean at this season, is fed by the region of extraordinarily high pressure which overspreads the Asiatic continent; consequently, this atmospheric current is cold and dry. On the other hand, the S.E. trade arrives at the region of calms heavily charged with vapour, which is condensed into rain in the region of calms between the two trades. As the precipitation proceeds, the pressure is diminished, and the N.W. monsoon advances sometimes along its whole extent southwards to the tropic of Capricorn, or beyond it. When the vapour has been deposited, the S.E. trade gradually returns, and the N.W. monsoon recedes before it till they regain their normal positions, which they retain till the vapour again accumulates, when a recurrence of the same phenomena takes place. The two winds thus oscil

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