Sundial

a device indicating the time of day by means of a shadow falling on a dial. The dial is usually a circular surface marked off with the hours like the face of a clock. The time or hour of the day is indicated by a shadow cast by means of a triangular finger; hence the expression, "the finger of time." This finger stands at the center; its index edge must be parallel to the earth's axis, that is to say, the finger must point toward the North Star. Sun dials are of use, of course, only when the sun shines and in the daytime. In its essentials this method of telling time differs in no important respect from a shadow cast by a church steeple, a tree, or a fence post by which the farmer and others engaged in outdoor employment are wont to note the dinner hour. The fact that the shadow cannot fail to advance with the progress of the sun has led to the proverbial expression, "as true as the dial to the sun." The Egyptian peasant constructs a sundial by thrusting a palm stem into the earth. This he surrounds with a rude circle of stones. George Washington's sundial at Mt. Vernon bears the truthful inscription, Horas non numero, nisi serenas, I record none but sunny hours. See Newton; Clock; North Star