STORIES OF USEFUL INVENTIONS, excerpt
By S. E. Forman

1911

THE CLOCK

"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?

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.

What is the central idea of the last paragraph?

Burning things is a great way to tell time.
Fire-clocks are dangerous because they can burn you.
There have been multiple types of fire-clocks to tell time.
Sundials are a means of observing shadows, not an invention.