The sun-dial can hardly be called an invention; it is rather an observation. There were, however, inventions for measuring time in the earliest period of man's history. Among the oldest of these was the fire-clock, which measured time by the burning away of a stick or a candle. The Pacific islanders still use a clock of this kind. "On the midrib of the long palm-leaf they skewer a number of the oily nuts of the candle-nut-tree and light the upper one." As the nuts burn off, one after another, they mark the passage of equal portions of time. Here is a clock that can be used at night as well as in the daytime, in the house as well as out of doors. Mr. Walter Hough tells us that Chinese messengers who have but a short period to sleep place a lighted piece of joss-stick between their toes when they go to bed. The burning stick serves both as a timepiece and as an alarm-clock. Fire-clocks of one kind or another have been used among primitive people in nearly all parts of the globe, and their use has continued far into civilized times. Alfred the Great (900 A. D.) is said to have measured time in the following way: "He procured as much wax as weighed seventy-two pennyweights, which he commanded to be made into six candles, each twelve inches in length with the divisions of inches distinctly marked upon it. These being lighted one after another, regularly burnt four hours each, at the rate of an inch for every twenty minutes. Thus the six candles lasted twenty-four hours."[19] We all remember Irving's account of time-measurement in early New York: "The first settlers did not regulate their time by hours, but pipes, in the same manner as they measure distance in Holland at this very time; an admirably exact measurement, as the pipe in the mouth of a true-born Dutchman is never liable to those accidents and irregularities that are continually putting our clocks out of order." This, of course, is not serious, yet it is an account of a kind of fire-clock that has been widely used. Even to-day the Koreans reckon time by the number of pipes smoked. If we could step on board a Malay proa we should see floating in a bucket of water a cocoanut shell having a small perforation through which the water by slow degrees finds its way into the interior. This orifice is so perforated that the shell will fill and sink in an hour, when the man on watch calls the time and sets it to float again. This sinking cocoanut shell, the first form of the water-clock, is the clock from which has been developed the timepiece of to-day. With it, therefore, the story of the clock really begins. In Northern India the cocoanut shell is replaced by a copper bowl (Fig. 3). At the moment the sinking occurs the attendant announces the hour by striking upon the bowl. [Illustration: FIG. 3.--AN EARLY FORM OF THE WATER-CLOCK.]