one part to religious duties, one to the affairs of his kingdom, and the remainder to bodily rest. To secure an equal division of the day he procured a definite quantity of wax which he had made into six candles, of twelve inches in length, and all of uniform weight, for he found that each inch in length of candle would burn for twenty minutes--one candle for each four hours. This was an approach toward accuracy and it was effective for night use as well as for the daytime. [Illustration: ASSEMBLING DEPARTMENT IN A FAMOUS AMERICAN WATCH FACTORY] Perhaps the earliest mechanical time measure was the clepsydra, or water clock. It is quite probable that, in its earliest form it consisted of a vessel containing water, which was allowed to escape through a small orifice. Suitable marks, or graduations, on the sides of the vessel served to indicate the lapse of time as the water gradually receded. This device was constructed in a variety of forms, some of which employed some simple mechanism also; but from their nature they could not give very accurate indications concerning the passage of time. The “hour glass” was another form of time indicator, which was capable of uniform, though extremely limited, action. It is said that its original use was to limit the length of sermons. It is interesting to note that discoveries and inventions, which may seem slight in themselves, sometimes form the basis of, or contribute to, other important inventions. In the year 1584 a bright young Italian was sitting in the gallery of the cathedral, in the City of Pisa, and as the lofty doors of the building opened to admit the incoming worshipers, a strong draft of air caused the heavy chandelier, which was suspended from the lofty ceiling, to swing quite a distance from its position of rest. This unusual movement attracted the attention of the young man, and as he continued to watch its deliberate movements, he did more than watch. He thought--for he noticed that the time occupied by the movement of the chandelier from one extreme position to the opposite point, seemed to be exactly uniform. He wondered why. It is the careful observation of things, and the trying to learn why they are as they are, and why they act as they do, that enables studious people to discover the laws which govern their actions. This young man, Galileo, was a thinker, and while some of his conclusions and theories have since been found erroneous, his thinking has formed the basis of much of the scientific thought and theory of later years. Galileo’s swinging chandelier was really a sort of a pendulum, and we have made mention of it because it has been found that no mechanical means for obtaining and maintaining a constant and accurate movement will equal the free movement of a vibrating pendulum. This fact has led to its adoption as a means of regulating the mechanism of clocks. For, when operated under the most favorable conditions, such a clock constitutes the most