This dam was built under the supervision of Mr. Robt. K. Martin. Construction was begun in 1864, and the dam was finished in 1870. Mr. Alfred M. Quick, present chief engineer of the water-works of the City of Baltimore has given a very lucid description of this work in Engineering News of Feb. 20, 1902. Fig. 26 is a cross-section of this dam, showing the method of construction so clearly as to scarcely need further description. The banks D-D on either side of the central puddle wall were carried up in 6-in. layers with horses and carts, and kept about 2 ft. higher than the puddle trench, which always contained water. The banks E-E were made of dumped material, after which the basins F-F were first filled with water and finally filled by dumping material into the water from tracks being moved in toward the center. [Illustration: FIG. 26–WORKING CROSS-SECTION OF DRUID LAKE DAM.] After reaching the top of this fill, banks B-B-B were built up in layers similar to D-D. The second set of basins C-C were then filled in a manner similar to F-F. The remaining portion A-A was constructed in layers like D-D and B-B, with the addition of compacting each layer with a heavy roller. Finally the inner face slope was carried up in 3-in. layers and thoroughly rolled, after which 2 ft. of “good puddle” was put upon the inner slope the latter was rip-rapped, the crown covered with gravel and the rear slope sodded. Some years after completion, a driveway was built along the outer slope, as shown, which had a tendency to strengthen the dam, though not designed expressly for that purpose. It is of interest to know that the influent, effluent and drain pipes were originally constructed through or under the embankment. These pipes were laid upon solid earth, and where they passed through the puddle wall were supported upon stone piers 6 ft. apart. As might be expected, they soon cracked badly and were finally abandoned, new ones being placed in the original ground at the south side of the lake. Mr. Quick states that so far as is known there has never been any evidence of a leak through the embankment during these 32 years of service. New Types of Dams; Bohio, Panama Canal. A brief description will now be given of three different dams designed for Bohio, on the proposed Panama Canal. Mr. George S. Morison’s paper before the American Society of Civil Engineers, on “The Bohio Dam,” and the discussion thereon, especially that by Mr. F. P. Stearns, were quite fully reported in Engineering News for March 13 and May 8, 1902. In constructing the Panama Canal it will be necessary to impound the waters of the Chagres River, near Bohio, to maintain the summit level of this canal and supply water for lockage.