It is remarked in the account of the works from which we derive these particulars, " that the shaking of pipes by carting, effectually tries them for that of two similar parcels of pipes, equally well cast at first, that which has been carted twenty miles before itwas proved, will exhibit a greater number of defective pipes than that which has been proved at the manufactory. Hence pipes should always be proved at the place where they are delivered, and not where they are made."

The whole supply from the Fountainhead, is conveyed in a single line of pipes, commencing at twenty, and tapering off, as the descent increases, to fifteen inches ; the

daily delivery is estimated at about 1,600,000, gallons. Mr. Telford, the engineer, computes the full supply for a town, at nine gallons for each inhabitant. The population of Edinburgh and Leith, at the time these works were completed, was about 153,000, of whom those in the country parts, intervening between Edinburgh and Leith, and on the outskirts of both, derived water from wells, springs, and rivulets.

The remarkable features of this aqueduct, are :

First. A large and beautiful compensation reservoir, formed by constructing a vast mound, 450 feet in thickness, 120 feet high, and 300 in length, across a valley, in order

to collect and store up the flood waters of the valley, and subsequently to distribute them to the mills below, in compensation for the water of the Crawley Springs, diverted from

their former destination.