Engineering Wonders of the World
Volume III

TRANSPORTATION CANALS OF THE UNITED STATES. 173 LOG RAFT, TUG, AND BARGE AT A LOCK ON A CANALIZED RIVER. carry and dump earth and rock from the canal bottom to the spoil banks, hun- dreds of feet away, removing in a ten- hour shift an average of 500 cubic yards. The canal was in some places cut a depth of 30 to 40 feet, through rock, with the aid of dyn- amite. Machines known as “ chan- nellers ” cut l|-inch crevices along the 26 feet deep, 300 feet wide on the surface. The sewage it carries is rendered innocuous by the immense flow of water. Formerly the sewage flowed into Lake Michigan through the Chicago River ; but so many water supplies were polluted, and so much life en- dangered, that this canal was devised to cure the trouble, and also to make the city of Chicago queen of inland ports. Wonderful mod- ern machinery was used in the con- struction of the canal. Only two locks, of the new pneumatic typo, will be required for its entire length. Immense bridge- like iron structures of the cantilever A NEEDLE DAM, WITH NEEDLES REMOVED (ON THE RIGHT). A barge is seen removing those of the left-hand portion. type, swinging like see-saws in mid-air, sides of the canal. In these, dynamite or gelatine was explodéd, leaving a perfectly smooth vertical face. The engineers also used ingenious dredges of huge proportions. A floating barge con-