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Show CLOCKS That NEVES NEED WINDINf j "LOCKS that tell the time with, only one hand were L. recently described in these pages. Now cornea another novelty in timo-keeplug devices in tho ( shape of a clock which never needs winding. It will run forever or at least until its metal parts -wear out. This sounds like the old fallacy of perpetual motion, but, as a matter of fact, is far from it. The new clock j runs by using In an Ingenious way the energy produced ? by changes In temperature. S MetaJ bars, which aro very sensitive to temperature l changes, are arranged in such a manner that when the S mercury falls and the bars contract this slight motion I of tho metal Is fully used. When the thermometer goes J up and the bars expand slightly, the motion involved J jn their lengthening is also made to do work The motion from the bars lifts tiny steel balls from hts Reserved. a lower reservoir to an upper one. Thorc lney jJK to turn a wheel In much the same way that T"2 turns an old-fashioned water wheel. Tho energy resulting from the expansion i j traction of metal as the temperature cJIfJfcjM used only to operate mechanism like that oi "VZM watches, which requires only 3 small anioM It is too expensive to be used where mucn p required. , hI, JP Somebody with a fondness for mathematics mated that to generate a single borse-po" H way would cost nearly 550,000,000. 1JtiiB' This tigure is based on the assumption "'lrrrtB clock will run twenty-four hour3 on the c neii sented by dropping one pound nuo foot. a jjm would cost ono dollar for enough metal bars -m this amount of power. IE |