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.

Second. Its tunnels : the first of them, in the city, passed under Watson's and Heriot's hospital, at the depth of 70 or 80 feet below the surface. The second, at the Castle Wynd, which passes obliquely through the solid rock of the castle, emerging at the west side of the mound. This tunnel is 700 feet long, and passes under the reservoir (which, nevertheless, is supplied by a pipe from it, ascending on the outside of the rock.)

at the depth of 120 feet,

Glasgow, more populous than Edinburgh, is supplied by steam power from the waters of the Clyde. The peculiarity of the principal works of this city, for there are two the Glasgow works of which we are first to speak, and the Cranston Hill Works

is, that the channels and reservoirs into which the water, percolating through a sandy soil,