Dams

Structures to impound or divert the water of IMG:content-1085.jpg:[graphic] IMG:content-1086.jpg:[graphic] IMG:content-1087.jpg:[blocks in formation] a dam nearly 30 miles long. When water is to flow over the top of a dam it must be built of timber or stone. The largest masonry dams are those at Villar in Spain, 175 feet high, and at Furens in France, 174 ft. high. The Quaker Bridge Dam, proposed for the Croton water supply of New York, is to be 265 ft. high, 22 ft. wide at the top, and 216 ft. wide at the base. The dam at San Mateo, Cal., 170 ft. high, is built of concrete. Masonry dams are usually built with curved profiles, to economize materials. Several failures of earthen dams, causing much destruction of life and property, have occurred. The most disastrous was that of the reservoir at Johns town, Pa., which