supported by the opinions of high naval authorities.
A study of the Canal reveals to us several vital and vulnerable points which, in the writer's opinion, could easily be destroyed from the air. The most vital and probably the most vulnerable of these are the great concrete locks which will lift vessels over the continental divide. They are six in number—three at Gatun, about eight miles from deep water on the Atlantic side of the Canal, and three at the west end of Culebra Cut, about the same distance from the Pacific.
The lock-gates are colossal built-up steel leaves, thick enough to drive an automobile on top. They are mounted in pairs and are opened and closed by electrical machinery. The upper gates of each lock are double, as a precaution against accident, and have an ingenious arrangement of emergency dams and floating steel caissons, designed to stem the torrent, in case a gate should be smashed, and to allow the gate to be repaired. These locks—especially the double gates, emergency dams and floating caissons—offer an admirable target from the air.
Gatun Dam is built across the valley of the Chagres river, one and one-half miles, and is buttressed at either end by the hills. Its most vulnerable part, outside of the locks, is naturally the "Spillway"—a weir twelve hundred feet long with a slope three hundred feet in width over which the surplus
