Page:Popular Science Monthly Volume 88.djvu/520

 492

��Popular Science Monthly

���rin Press Association

The "Cascadas" is the largest all-steel dredge in the world. It scoops up fifteen wagon-loads of material at a time, and has disposed of as many as seventeen thousand wagon-loads of

earth and rocks in a single day

Digging Away the Slides at Panama

��THE whole Panama Canal zone may be imagined as an aggregation of slopes of hard material upon which softer materials rest. In cutting the canal the equilibrium maintained be- tween the upper and the lower strata was disturbed. As a result the overlying material tobogganed down into the cut which constitutes the canal, upon the inclined under material. Nothing can stop the movement now in progress until the angle of repose is attained, and this

��can be reached only by removing the excess amount of material. Col. Goeth- als states that seven million cubic yards must be remo\ed before the slides are entirely stopped, and that this is at best only a guess. "It must not be inferred," says Col. Goethals, "that the canal will be closed until this amount is dredged ; on the contrary, it is the intention to pass ships as soon as a channel is secured through the remaining six hundred feet, and there are reasonable grounds for as-

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