Locks, usable length 1,000 feet. Locks, usable width 110 feet. Gatun Lake, area 164 square miles. Gatun Lake, channel depth 84 to 45 feet. Excavation, estimated total 174,666,594 cubic yards. Concrete, total estimated for canal 5,000,000 cubic yards. The Gatun is the greatest rock and earth-fill dam ever attempted. Forming Gatun Lake by impounding the waters of the Chagres and other streams, it will be nearly 1-1/2 miles long, nearly 1/2 mile wide at its base, about 400 feet wide at the water surface, about 100 feet wide at the top. Its crest, as planned, will be at an elevation of 115 feet above mean sea-level, or 30 feet above the normal level of the lake. The interior of the dam is being formed of a natural mixture of sand and clay placed between two large masses of rock, and miscellaneous material obtained from steam-shovel excavation at various points along the canal. Gatun Lake will cover an area of 164 square miles, with a depth in the ship channel varying from 85 to 45 feet. The necessity for this artificial lake is because of the rugged hills of Panama. A sea-level canal would have been a financial impossibility. By a lock system lifting vessels up to Gatun Lake (a height of 85 feet), an immense amount of excavation was saved. Incidentally the alarm was allayed of that ingenious speculator who foretold that the Gulf Stream would take a new path through the Panama Canal and desert the West Coast of Europe, on the climate of which it has so profound an influence. When the canal was opened England was to revert to her "natural climate"--that of Labrador! But since the canal will not be a sea-level one, it cannot of course have the slightest effect on ocean currents. The amount of Pacific and Atlantic water which will be mutually exchanged by its agency each year will be insignificant.