Show worlds best clock we think of greenwich time ai as absolutely accurate but the fact that it is sometimes a tenth of a second wrong worries the astronomers trono so they are building a new clock which will not vary more than a hundredth of a second the standard clock which never runs fast or slow is the revolving earth and the astronomers by observing the stars can tell the time with complete accuracy the new clock is like the plug in clocks but instead of regulating itself by the pulses of current from a dynamo it makes its own alternating current and times it perfectly by means of a piece of rock crystal which vibrates times a second |