PRIMITIVE CLOCKS. 181 



than for use. In the days when dials were used, each one contained 

 a motto of some kind, like these : " Time flies like the shadow " ; or, 

 "I tell no hours but those that are happy." 



But the dial could be used only in the daytime ; and, even then, 

 it was worthless when the sun was covered with clouds. In order to 

 measure the hours of the night as well as the hours of the day, the 

 Greeks and Romans used the clepsydra, which means, " The water 

 steals away." A large jar was filled with water, and a hole was made 

 in the bottom through which the water could run. The glass, in those 

 days, was not transparent. No one could see from the outside how 

 much water had escaped. So there were made, on the inside, certain 

 marks that told the hours as the water ran out ; or else a stick with 

 notches in the edge was dipped into the water, and the depth of what 

 was left showed the hour. Sometimes the water dropped into another 

 jar in which a block of wood was floating, the block rising as the hours 

 went on. Once in a while, some very rich man had a clepsydra that 

 sounded a musical note at every hour. 



Another way of measuring time among the ancients was by the 

 sand, or hour-glass. This was made of pear-shaped bits of hollow 

 glass with a very small opening between them. It held just sand 

 enough to run from the upper into the lower pear in the space of one 

 hour. The glass was then turned the other side up and the sand ran 

 back, also taking an hour. You have seen glasses of this kind where 

 the sand runs out in three minutes. They are used for boiling eggs. 

 King Charlemagne, a thousand years ago, had a glass of this kind that 

 ran for twelve hours without turning. It was marked on the outside 

 with red lines to show the escape of the sand. Hour-glasses were so 

 common after this that they were carried in the pocket like watches. 

 Every minister had one to mark the length of his sermon, which was 

 a very serious matter in England during the protectorate of Cromwell, 

 very few sermons being as short as one hour. It is said of one min- 

 ister that when the sand ran out of his glass he turned it over, saying, 

 " I know that you are all good fellows, so let's have another glass." 

 Once, when the preacher had turned his glass a second time, showing 

 that he had already preached two hours, the sexton asked him to lock 

 the door and put the key on the nail when he was through, because 

 the few people that were left wanted to go home to dinner. We also 

 read that, in the early history of New York, the soldiers who defended 

 the city used hour-glasses to tell when they should go on guard. 



We have seen that the dial could be used neither at night nor in 

 cloudy weather. We have also noticed that the hour-glass had to be 

 watched so that it might be turned at the very moment the sand ran 

 out. And we have also seen how inconvenient it was to measure time 

 by the running of water. None of these ways was accurate enough, 

 for minutes and even hours would be lost. A better means of measur- 

 ing time was sought for ; and this was found by means of a clepsydra, 



