NDIA, profiting by long and sad experience, has provided, as far as may be possible, against the contingencies of drought and famine, by the establishment of a magnificent system of storage reservoirs, to furnish water for irrigating when rain is wanting. Some of these tanks are fine specimens of engineering, and so far as records go, no disaster has ever attended their establishment. But to be ready and efficient, for purposes of irrigation, the water must be above the level of the surrounding country: hence, the only practicable plan has been to dam up the courses of streams and ravines in the hills. As nearly all Bengal is comparatively low and level, this method is not applicable there; hence, the terrible famines consequent in a comparatively small decrease of the average rain supply. But in the Deccan, in the Madras presidency, and in Ceylon, the reservoir system has been carried to an extent astounding to the white man, who depends with tolerable certainty upon the rain, and who is accustomed to consider other races as universally indolent and improvident. In fourteen districts of the Madras presidency
MAP OF CONEMAUGH VALLEY.
are nearly fifty-five thousand irrigation reservoirs, four-fifths of which are in regular operation. Their size may be estimated by the fact that the retaining dykes average half a mile in length. One ancient reservoir, now broken, had a dam thirty miles long, shutting in an artificial lake of eighty square miles. The Veranum tank covers fifty-three square miles, has a dam twelve miles long, and produces $55,000 per year. In Ceylon may be seen a gigantic dam of cemented stone, fifteen miles long, one hundred feet wide at the base, and forty feet wide at the top.
The same plan is of late years being extensively operated in our western tracts for the reclaiming of extensive tracts otherwise not cultivable. With these exceptions no great use of the reservoir system has been made in this country. Every saw-mill, grist-mill or factory in our land usually has its dam in an adjacent stream to insure a fair supply of water: but none of these can be properly considered general precautions against drought. The only prominent public works of the sort are the Croton storage reservoirs, by which New York is supplied with water. There are eighteen reservoirs, with a total capacity of fourteen thousand millions of gallons. China has a great canal irrigation system, which is, perhaps, safer in some respects than the Hindoo system, but which can not command as large an increase of supply in time of drought, the water being drawn from the rivers, and thus having comparatively little fall. But the canals so thoroughly intersect the whole country as to serve as public highways: and in many sections there are no other roads.