We do not hear much about the youthful father of pneumatic engineering, possibly because he lived so very long ago, but his story is fully as interesting as that of Watt or Galileo or Newton. Young Ctesibius dwelt in the city of Alexandria, Egypt, 250 years before the birth of Christ. His father kept a barber shop, and the young lad used to watch his father practice his tonsorial art on the Greek and Egyptian dandies of the time. No doubt Ctesibius’s father expected to make a first-rate barber of his son, but history does not tell us much about his early life.
The barbers of those days had their mirrors as do the barbers of the present time. But a mirror in those days was a treasured possession. It consisted of a brightly polished plate of metal in which a person could see himself “darkly” or it might have been a plate of glass with a black backing. These mirrors had to be carefully preserved from injury and from moisture, and so, instead of having them mounted on the wall as in a modern barber shop, they were stowed carefully away and brought out only after the tonsorial artist had completed his operation and was ready to exhibit his finished product to the customer.
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.
RAISING WATER WITH ATMOSPHERIC PRESSURE
