THE BOY WHO DISCOVERED COMPRESSED AIR
Now in the tonsorial parlors of Ctesibius’s father the precious mirror was suspended above the head of the customer and when the barber had finished the shave or haircut he pulled down the mirror and let the customer survey his remodeled countenance. After the customer viewed himself to his heart’s content he merely released the mirror and it was automatically drawn back into place by a counterweight that slid in a case fastened to the wall. Young Ctesibius noticed that every time the mirror was released a curious whistling sound came from the case in which the counterweight moved. No doubt this phenomenon had been recurring day after day for years, but it excited no more curiosity than would a squeaky door, until, one day, the barber’s son happened to notice it. Immediately he was all curiosity. No one knew anything about air in those days and the boy could get no satisfactory explanation of the phenomenon, so he started an investigation of his own. He found that the counterweight fitted very closely in its case and when it dropped it forced a stream of “wind” out of a crevice which produced a whistling sound. That set Master Ctesibius to thinking. He had discovered a method of harnessing the wind. No more barber shop for him; he was launched upon a career of scientific research and invention.
The first use he made of his discovery was to build a pipe organ which was driven by a water wheel and hence was known as a water organ. But there were other and more lucrative fields for the newly discovered power. Being invisible, compressed air proved a most valuable medium for performing seemingly miraculous tricks with which the corrupt priesthood of that time hoodwinked the public. Naturally such air-controlled apparatus was kept secret, and we have only a meager record of a few of the ingenious devices used in the temples. However, Ctesibius made many scientific discoveries and became the most famous mathematician and scientist of his age. We have read in Chapter IV of his famous water clock adjusted to record hours of varying length according to the season.
While Ctesibius is credited with being the first man to make scientific use of compressed air, the use of free air or wind as a power far antedates him. Sailing vessels were probably in use long before windmills were invented. As pointed out elsewhere, windmills possessed an advantage over water wheels in that they could be placed anywhere, instead of being confined to the banks of streams. They were widely used for pumping water, grinding grain, and sawing wood until the steam engine arrived and displaced them.
Although wind power is but little used to-day, air is much more widely used in modern machinery than is generally realized. A catalogue of the various devices in which it plays a prominent part is likely to prove astonishing. For instance, we employ it to bore through rock, to stop the speeding express train, and even to quell ocean billows. Being elastic and compressible, it makes an ideal spring for the storage of power and a cushion for absorbing shocks. It is also used to fight back water and permit men to work in the depths of the sea or in water-bearing sand and earth.
Despite his extensive use of air Ctesibius knew nothing of the atmospheric pressure. It was not until the seventeenth century that atmospheric pressure was discovered and measured. It was then learned that there is no such thing as suction.