Stories of Useful Inventions

by S. E. Forman

"Tic-tac! tic-tac! go the wheels of time. We cannot stop them; they will not stop themselves." Time passing is life passing and the measurement of time is the measurement of life itself. How important then that our chronometers, or time measures, be accurate and faithful! It is said that a slight error in a general's watch caused the overthrow of Napoleon at Waterloo and thus changed the history of the world. Because of its great importance the measurement of time has always been a subject of deep human interest and the story of the clock begins with the history of primeval man.

The larger periods of time are measured by the motion of the heavenly bodies. The year and the four seasons are marked off by the motion of the earth in its long journey around the sun; the months and the weeks are told by the changing moon; sunrise and sunset announce the coming and the going of day. The year and the seasons and the day were measured for primeval man by the great clock in the heavens, but how were smaller periods of time to be measured? How was the passing of fractional parts of a day, an hour or a minute or a second to be noted? An egg was to be boiled; how could the cook tell when it had been in the water long enough? A man out hunting wished to get back to his family before dark: how was he to tell when it was time to start homeward?

FIG. 1.—A PRIMITIVE SUN-DIAL.

FIG. 2.—A MODERN SUN-DIAL.

Plainly, the measurement of small portions of time was a very practical problem from the beginning. The first attempt to solve the problem consisted in observing shadows cast by the sun. The changing shadow of the human form was doubtless the first clock. As the shadow grew shorter the observer knew that noon was approaching; when he could reach out one foot and step on the shadow of his head he knew it was time for dinner; when his shadow began to lengthen he knew that evening was coming on. Observations of this kind led to the shadow clock or sun-dial (Fig. 1). You can make one for yourself. On a perfectly level surface exposed all day to the sun, place in an upright position (Fig. 1) a stick about three feet long, and trace on the surface the shadows as they appear at different times of the day. A little study will enable you to use the shadows for telling the time. Sun-dials have been used from the beginning of time and they have not yet passed out of use. They may still be seen in a few public places (Fig. 2), but they are retained rather as curiosities than as real timekeepers. For the sun-dial is not a good timekeeper for three reasons: (1) it will not tell the time at night; (2) it fails in the daytime when the sun is not shining; (3) it can never be used inside of a house.

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.