Science: Tide-Harnesser

At Keokuk, la., a vast power dam sprawls across the Mississippi River. Before it was built, many an engineer scratched his head ruefully, doubted that it could be done because of the vagaries of the banks of the Father of Waters.

At Niagara's Horseshoe Falls, there is an enormous power plant. Before it was built, engineers had gasped at the thought of such a thing.

At Muscle Shoals, Ala., the world's largest hydro-electric plant —600,000 h. p. in spring floods, 100,000 h. p. minimum—is now being built. Its construction is under the astute eye...