Page:Popular Science Monthly Volume 74.djvu/430

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PSM V74 D430 Las cascadas slide culebra division 1908.png

Las Cascadas Slide, Culebra Division, April, 1908. Area of Slide, 5,433 Square Yards. Estimated amount of material in motion, 100,000 cubic yards. This slide started in the dry season and extended back 230 feet from the edge of cut and to within 50 feet of the crest of the hill.

Mr. Bunau-Varilla, a civil engineer who was at one time chief engineer, of the Panama Canal Company, proposed a project with a summit level at 130 feet; but with all locks so arranged that there could he a gradual progress of excavation and deepening of the summit level with a successive cutting out of locks until finally the lock canal was converted into a sea-level canal.

Major Gillette advocated a lock canal with its highest section at 100 feet above sea-level.

The sea-level canal committee of the board of engineers reported in favor of a canal 40 feet deep, with a bottom width of 150 feet in earth, and side slopes adjusted to the nature of the ground so as to give a surface width of 302 to 437 feet. The bottom width in rock was to be increased to 200 feet and the surface width in rock was to be 208 feet. At the Pacific end the canal was to he protected by a tidal lock located between Ancon and Sosa hills. The plans, as proposed by the committee, included a dam at Gamboa across Chagres River of either masonry alone or of earth and masonry combined. This dam was necessary for the control of the river.

The dimensions of the canal of the committee project at the point of deepest cutting near Culebra are as follows: Bottom width, 200 feet; the hanks to have a hatter of 1 in 10 rising from the bottom to a berm 10 feet above the water surface; the berm to he 45 feet wide (according to diagram; 5(» feet according to text of report); then a succession of bank slopes with a batter of 1 in 4 and a rise each of 30 feet, one above the other, with intermediate berms each 121/2 feet wide up to the rock line—shown by a diagram for the point known as Kilometer 54.41 in