To complete this notice of wells, it may be added that in our own country, ac- " From the cording to Mr. Flint, ancient wells have been found. highest point on the Ohio, to St. Charles on the Missouri, and far up the Upper Mississippi and Missouri, the more the country is explored and peopled, and the more its surface is penetrated, not only are there more mounds brought to view, but more incontestible marks of a numerous population. Wells artificially walled, different structures of convenience or defence, have been found in such numbers as no longer to excite curiosity."

For a long period, the only mode of raising water from wells, was by letting down vases or buckets into them by a cord, but gradually the pulley and windlass succeeded, and even irrigation in Eastern countries, upon which the success of their agriculture depends, was carried on by water thus raised from wells, and borne by laborers to the field.

The excessive labor and inconvenience of this practice, led to the formation of vast tanks for the collection of water, from which it might be conducted in open channels to the points proposed. In comparison with some of these tanks, our largest " In the Carnatic, reservoirs sink into insignificance. it is recorded, that there are tanks eight miles in length and three in breadth. In Bengal, they frequently cover one hundred acres, and are lined with stone." Knox, in his Historical Relations of Ceylon, says the natives formed tanks two or three fathoms deep, some of which were in length above a mile.