THE canal now being constructed by the American Government in continuation of the work commenced by de Lesseps is 50½ miles long from deep water in the Caribbean to deep water in the Pacific. Of this distance 34 miles is high-level with 8 miles sea-level at each end, as shown on the accompanying profile. The water for lockage is supplied by blocking the lower valley of the Chagres River at Gatun with an earthen dam 7000 feet long, 115 feet high, and about 2000 feet broad. This consists of two heaps of broken rock enclosing the hydraulic fill, i.e. silt pumped in wet and allowed to odrain. This packs tightly under the pressure of the atmosphere, and secures the impermeability of the dam. The heavy rock fills secure its stability against the lateral pressure of the 85 feet of water which will be behind the dam. The height now attained by the dam is 70 feet. The underlying ground is somewhat soft, but it has not been squeezed up owing to the way the load has been ospread. The sides of the dam, in fact, hold down the ground so that the weight of the central portion cannot squeeze it up.