From the Receiving Reservoir the water is conducted (a distance of two miles) in iron pipes to the Distributing Reservoir, where the surface of the water is 115 feet above the level of mean

tide. This last is the height to which the water may generally be made available in the city.

GENERAL CONSTRUCTION OF THE AQUEDUCT.

Plate I. is a section of the Aqueduct showing the form of the masonry used in earth excavations. The foundation is formed with concrete ; the side walls of stone ; the bottom

and sides of the interior being faced with brick, and the top covered with an arch of brick. In forming the concrete a mortar is made by mixing three parts of sand with one of hydraulic lime, and then mixing about three parts of stone, broken to a size allowing them to pass through a ring an inch and a half in diameter. Having thoroughly mingled the broken stone and mortar, the concrete is placed in its proper position and form, and brought into a compact state by using a pounder ; and is then suffered to remain until it set, or become indurated, before any work is commenced upon it. The object should be to mix as many stones or pebbles as will thoroughly bed in the mortar, allowing none of them to come in contact, but all to

be enveloped in mortar. This forms a body which becomes indurated and makes a foundation under the whole length of the Aqueduct like one continuous stone. It attains a degree