excluding those in the extreme north, are not very different. On the other hand, it is hardly possible to imagine greater contrasts than those which often exist between the climates of various parts of India.

Take, for example, the two extremities of the great northern plain, Sindh on the western, and Lower Bengal on the eastern side of India. These countries are almost in the same latitude; each of them is an unbroken alluvial plain, slightly elevated above the sea. In Sindh, so little rain falls that the country may be said to be rainless. It is the Egypt of India, and without artificial irrigation would be an uninhabitable desert. Bengal, on the other hand, is a country of abundant rain and luxuriant vegetation. The rainfall on the mountains along its eastern borders is heavier than any that has been observed in any other part of the world. At Cherra Punji, on the Khasiya hills, on the frontiers of Eastern Bengal, 600 inches is not an unusual fall for the year; sometimes it is much more. The average annual rainfall of London is about 25 inches, a quantity less than that which sometimes falls in twenty-four hours in Eastern Bengal.

It is not difficult to imagine from this illustration, taken from two Indian provinces, how great must be the differences in physical conditions between countries presenting such extraordinary contrasts of climate.

The one characteristic, common at certain seasons. to the whole of India, except at great elevations, is excessive heat. The southern half of India, including the greater part of the Madras and Bombay Presidencies, lies within the tropic. The northern half, including nearly the whole of the Indo-Gangetic plain, lies outside the tropic. Although in the southern or tropical region the mean temperature of the year is higher, the varia

tions of temperature between summer and winter are comparatively small; and it is in the second region, in the plains north of the tropic, where the days are longer and the power of the sun more continuous, that Indian heat reaches in the summer months its greatest intensity. In parts of the Punjab and of the North-Western Provinces, and in the desert on the borders of Sindh, the temperature in May and June is probably exceeded in no part of the world; but this extreme heat brings by its own action the relief without which all life would perish.

'The dominant feature of Indian meteorology (I am quoting from Mr. Blanford, the head of the Meteorological Department in India) is the alternation of the monsoons, the annual reversal of the prevailing windcurrents. This alternation is consequent on the fact that, in the early summer, the broad plains and tablelands of India are heated to a far higher temperature than the seas which bathe their shores; whereas, in the winter, the seas retain much of their warmth, while the land radiates away and throws off into stellar space much more heat than it receives from the oblique rays of the sun during the shorter winter days, and, especially as regards Northern India, speedily cools down to a temperature much below that of the surrounding seas.' 1 Observations of these phenomena and their consequences, especially in regard to the winds and the rainfall, show us, as Mr. Blanford says, how each season in succession affects in diverse modes the different portions of the country; why one province may sometimes be devastated by flood while another is parched with drought, and why, with special adaptation to the peculiarities of its own seasons and resources, each of 1 Statistical Atlas of India, chap. iii.

them has its own agricultural system, its own staples, its own rotation of crops.'

After March the heat in Northern India rapidly increases. As the air above the heated earth becomes hotter, the pressure becomes less. At the same time an increase of pressure is going on over the ocean south of the equator, which has then its winter. Thus, a current of air laden with moisture is gradually established towards the continent of India from the sea. This is the so-called south-west monsoon, which brings the periodical rains every year to India, when the heat of the summer has reached its greatest intensity. Towards the end of May the monsoon has usually become established in the south-western extremity of India, and before the end of June it has extended to the greater part of the northern provinces.

The quantity of rain that falls in any part of India depends mainly on the configuration of the surface of the land, and on its situation with reference to the vapour-bearing winds. As the amount of watery vapour which air can hold in suspension varies with the temperature of the air, and increases with the temperature, any cause which cools the current from the sea leads to condensation of the vapour and to the fall of rain.

One of the chief of such causes is the existence of mountains which stand in the path of the winds, and force the vapour-bearing currents to rise over them. Thus, the range of the Western Ghats, which form an almost continuous barrier along the western coasts of Southern India, meet first the whole force of the monsoon as it comes saturated with moisture from the sea. A great condensation of rain is the immediate result of the fall in the temperature of the hot moist air as it is forced to rise in passing across the mountains. On the face of

the Ghats, not far from Bombay, the annual rainfall in some places exceeds 250 inches; but a very large part of the moisture which the current of air contains is drained away by the excessive precipitation near the coast, and, as the current flows on over the land, the quantity of rain is greatly reduced. At Poona, only sixty miles from the sea, the annual rainfall is not more than 26 inches.

Similar phenomena are observed in a still more remarkable form on the Himalaya. The line of maximum clevation is not far from the southern edge of the great mountain mass. When the monsoon winds strike the outer ranges of the Himalaya, a large amount of rain. immediately results; the quantity diminishes as the wind passes over the mountains, and when it reaches the regions of perpetual snow, about 100 miles from the plains of India, almost the whole of its remaining moisture is condensed. Thus, the periodical rains are completely stopped by the ranges of the southern face of the Himalaya; they can find no entrance to the mountains beyond, or to the tableland of Tibet, one of the driest and most arid regions of the world.

Similar causes shut off the rain-bearing southwesterly winds from the Madras provinces, on the south eastern coast of India. These winds cannot carry much moisture over the obstacle to their course formed by the Western Ghats, and little rain falls in the eastern districts of Madras during the summer months. But, as I shall presently notice, the remedy for this deficiency is not wanting.

Where, on the other hand, the configuration of the land is such that no obstacles are offered to the passage of the monsoon current from the sea, there may be no condensation of its moisture. Thus, when the wind

strikes upon the coast of Sindh, very slightly elevated above the sea, it finds a hotter and not a cooler surface than that which it has left, and it passes on with all its watery vapour for 1,000 miles across the rainless plains to the Punjab, where at last the Himálaya converts the vapour into rain. If, as General Strachey has observed, there had been a range of mountains connecting the high land of the Indian peninsula with that of Baluchistán, hardly a drop of rain would have reached the Punjab and the North of India.

It would be easy to multiply illustrations of the manner in which geographical position and configuration determine the fall of rain in the various provinces of India, and even local conditions of a kind which might have seemed of little importance produce remarkable results. Thus, for instance, a deep depression in a range of mountains may afford an opening for the entrance of the vapour-bearing streams, and give an ample supply of rain to a tract of country which would have been almost rainless if the mountains had been continuous. In this manner, the valleys of the Tapti and Narbada rivers, which enter the sea north of Bombay, are gates through which the monsoon finds access to the provinces of Central India, and makes them fertile and prosperous.

As the sun travels southward after midsummer, the south-west monsoon passes gradually away, and towards the latter part of September it ceases to blow over Northern India. Causes acting in the converse direction, but similar to those which brought it with its rain-bearing currents, lead to its cessation. The temperature falls as the sun goes south, and the vast dry tracts of the Asiatic continent become rapidly colder; the barometric pressure over the land increases, and

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