OF

NATURE AND ART.

CHAP. IV. ·

OF INDIA.

Periodical Winds, Springs, Cataracts, &c.

THE vast tract of country generally known by

the name of India, or the East Indies, is situated between sixty-six and one hundred and nine de

grees of east longitude, and between one and forty degrees of north latitude; being bounded by Tartary on the north, by China on the east, by the Indian Ocean on the south, and by Persia on the west.

A chain of mountains, which runs through the peninsula from north to south, is the cause of a very extraordinary phenomenon in natural history; for the countries separated by these mountains, though under the same latitude, have their climates and seasons so entirely different, that while it is summer on one side of the hills, it is winter on the other. On the western coast, which is usually distinguished by the name of the coast of Malabar, a south-wes. wind, begins to

VOL. V.

blow from the sea at the end of June, with continued rain, and rages against the land for four months, during which time the weather is calmn and serene on the coast of Coromandel; and towards the end of October, the rainy season, caused by the change of the monsoon, begins on the same coast; at which time the tempestuous winds make it so dangerous for ships to remain there, for the three ensuing months, that it is scarcely ever attempted. This occasions the periodical return of merchant vessels to Bombay, where there is a secure harbour and a convenient dock.

As the tropic of Cancer extends through the middle of this country, the air is-exceedingly hot, but in the most sultry season, rains cool the air, and refresh the earth. When these rains set in, a day seldom passes without terrible thunder and lightning; and even during the fair season, they have lightning, for several weeks together; but this is unattended with thunder, and seldom does any harm. The heavens are clear and serene, except in the rainy season, and the vernal equinox; for all the rest of the year is exempt from storms and hurricanes, and there are only such moderate breezes, as the heat of the climate requires. The pleasure to be enjoyed by a contemplative ambulator in a morning or evening is really inconceivable, for the sky not only seems to enjoy a purity and brightness that is never seen in our northern latitudes, but the trees retain a perpetual verdure, and both blossoms and ripe fruit may be seen on some tree or other, all the year round. At the end of the

season, indeed, the earth generally resembles

n desart; but the showers no sooner be

gin to fall, than it is almost instantly covered with grass and herbs. The soil, consisting of a rich brittle mould, is easily broken up, and prepared for tillage; and though the same land is sown every year, it never requires any manure, but is rendered sufficiently prolific by the an nual rains.

The regular winds on the coast of India, which seamen call monsoons, are observed to blow constantly six months one way, and six months another; namely, from April to October, or thereabouts, they blow from the south-west, and from October to April from the north-east, only varying now and then a point or two on either side. The shifting of these contrary winds, which is called the breaking up of the monsoons, is usually attended with violent storms or hurricanes, such as are very seldom experienced in Europe, and which render the navigation of the Indian seas peculiarly dangerous at that time of the year. Besides these periodical winds they have land and sea breezes, which shift once in twelve hours, except the monsoons are violent, for then the breezes give way to the tempest; and it is these sea breezes that are so refreshing to the southern parts of the country.

Having mentioned the monsoons, it may not he amiss, before we proceed farther, to enquire into the reason of that extraordinary phenome non. The cause then of these periodical winds is owing to the course of the sun northward of the equator one half of the year, and southward the other. While he passes through the six northern signs of the ecliptic, the vast countries of Arabia, Persia, India, and China, are heated, and reflect great quantities of the solar rays into

the regions of the ambient atmosphere, by which an it becomes very much rarefied, and has it's qualibu sum of course destroyed; to restore which, sit from the equatorial parts, where it is ede, as well as from the colder northern imes, must necesarily have a tendency, or molo, towards those parts, and so produces the

ons for the first six months, during which time the heat of those countries is greatest. ten for the other six months, the sun traversbug the occan and countries towards the southern pie, the air over those parts is most heated, and consequently the equatorial air alters its use, or the winds veer about, and blow upon the opposite points of the compass.

to account for another phenomenon, viz. the general trade winds, which do not shift like the

apons, but blow continually the same way, we must consider, that heat, by rarefying the air, makes it lighter in some places than it is in thers, and cold, by condensing it, makes it heavier. Hence it is, that in the torrid zone, this air, being more rarefied by the rays of the sun, is much lighter than in other parts of the atmosphere, and most of all over the equatorial parts of the earth. Now as the parts most rare

dare continually shifting toward the west, by the earth's diurnal rotation eastward, it follows, that those parts of the air which lie on the west side of the point of greatest rarefaction, and flow to meet it, have less motion than the on the east of the said point, which follow therefore the motion of the eastern air evail against that of the western, and so a perpetual east wind, if this were all i of that rarefaction. But as all the parts

of the atmosphere are greatly rarefied over the equator, and those about the poles are greatly condensed by extreme cold, this heavier air from each pole is constantly flowing towards the equator, to restore the balance destroyed by the rarefaction and levity of the air over those regions.

From these observations we may easily conceive, that by a composition of the two directions of the air from the cast and north, a constant north-east wind will be generated in the northern hemisphere; as the two directions from the east and south will produce a constant south-east wind in the southern hemisphere, to a certain distance on each side the equator. And this hypothesis we find to be verified in the general trade winds, which blow constantly from the north-east and south-east to about thirty degrees on each side the line, where the parts are over the open ocean, and not affected with the reflexion of the solar rays from the heated surface of the land; for in that case the air over the sea being cooler, sets in upon the land, as on the coast of Guinea, and in other parts of the torrid zone. Mr. Clare, in his "Motion of Fluids," ilustrates this matter by the following experiment. In the middle of a wide dish or vessel of water let there be placed a water-plate filled with warm water; the first will represent the ocean, the other an island rarefying the air above it. Then holding a candle over the cold water, blow it out, and the smoke will be seen to move towards the warm plate, and, rising over it, will show the course of the air from sea to land. If the ambient water be warmed, the plate filled with cold water, and the smoking wick of a