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What Working Engineers Knew!


Even without a knowledge of atoms, Hellenistic engineers came close to harnessing the power of steam in the ancient world. Based primarily in Alexandria, Egypt, they recognized the material nature of air and saw that it could exert large forces. They achieved some remarkable things during the three centuries before Lucretius.

Two of those engineers, Ktesibios, and Philon of Byzantium, built machinery, and they also led us toward a real-world understanding of gases. Ktesibios was born in Alexandria in 270 BC. We're told that his father, a barber, contrived a mirror that could be adjusted with a counterbalance, using a compressed air plunger. It could well be. Ktesibios went on to create all kinds of air and water powered machinery. He invented the earliest known water organ. It used a water piston to force air into organ pipes. He invented a compressed air pump, compressed air catapults.

Right on his heels, the Byzantine engineer Philon turned up in Alexandria. Philon created his own array of mechanical wonders. He also left behind a book titled Pneumatica in which he described a dazzling variety of pneumatic devices -- many of them invented by Ktesibios.

The parade of steam and air machinery continued until Imperial Rome absorbed Egypt in 30 BC -- after the death of Anthony and Cleopatra. Even then, steam had yet to make its best-remembered appearance in Alexandria. Pick up any book on ancient invention today, and you'll read about Hero's Turbine.

Approximate configuration of Hero's "Turbine"

It was built by Lucretius' contemporary, Heron of Alexandria -- a first-century BC builder of very sophisticated machines. His so-called Turbine was a steam-jet-powered whirligig device -- a toy for royal amusement that delivered no useable power. By then, Alexandrian engineers had used steam and air to make jet-propelled birds that flew on the ends of strings, automatic door openers, and much more.

Hero's Turbine was only one more late example of such machines. Yet it is the best-remembered one, even though it marked the end of a profoundly inventive age. It was an age that'd almost given us real steam engines, long before they finally arose in the eighteenth-century.

One other Hellenistic inventor worked directly with steam. But she had greater staying power during the long reign of alchemy, after Hero and Lucretius. Most of what we know about the chemist Maria the Jewess comes from an Egyptian alchemist named Zosimos. He wrote in the late days of the Roman Empire, five hundred years after she lived. Among other things, Zosimos talks about Maria's invention of a device called the kerotakis.

The kerotakis was one of many stills, boilers, and reflux condensers invented by Maria. In it, she boiled mercury or sulfur in a lower container, and used its condensing vapor to hold some other material at a certain temperature in the pan above. It was a high-temperature version of the double boiler. We cook food in the upper pan of our double boiler. It's nested in a lower pan of boiling water. Food stays at the same temperature as steam condensing below it -- 100°C. (By the way, the only reference to Maria that lingers in the modern world is the French word for a double boiler -- bain-marie, literally Maria's bath.)

A plain domestic double boiler, on sale in the 1900 Sears, Roebuck and Co. Catalog.

Maria founded an important school of chemistry in the late third century BC. She might even have met Archimedes or Ktsebios in Alexandria when she was young. She's called The Jewess because Zosimos called her a Sister of Moses. That may've been no more than a convoluted way of saying that she was wise. She could've been a Greek working in Egypt -- maybe even a Syrian.

Alchemists of a later age used fanciful and metaphorical language to describe her processes, but that was their rhetoric, not hers. Her thinking was closer to modern process engineers. Alchemy took on much of its arcane trapping during the classical revival that followed the wildfire spread of printed books in the late fifteenth century. But, even then, alchemists kept using Maria's condensers, boilers, and stills in their attempted transmutations of matter.

In any case, medieval philosophers had little more to say about the corporeal makeup of gases. Yet craftsmen produced many practical steam and air powered devices. Take the sufflator, used for blowing air into fireplaces. A sufflator was an andiron, shaped like the body of some beast. It was hollow and partially filled with water, and its head had pursed lips in the form of a nozzle. (Remember that lost woodsman in the woman's hut.) The fire heated the andiron and boiled the water. A steam jet, pointed at the fire, entrained air into it.

By the way, similar steam jet ejector pumps are still widely used in industrial devices that move air, since a small steam flow can draw a large air flow along with it. Sufflators were very effective machines.

Fireplaces evoked the motive power of gases in many ways. One medieval device was a small turbine, mounted in a chimney and driving a spit in the fireplace. That immediately evokes the most significant gas-driven medieval device of all, the windmill.

Windmills turned up in Europe just before AD 1200. European windmills used a fan facing into the wind, but the turbine-in-the-fireplace was actually closer to the earlier Arab windmill. The Arabs mounted their windmills inside closed towers. Louvers in the sides created a vortex whirl of air within the tower. They looked a lot like chimneys with turbine blades inside them.

Still, philosophers and craftsmen continued to live in different worlds. And change would not take place until they began talking with one another. When that happened, the result was the seventeenth-century scientific revolution. That's when, at last, we breathed anima into machines. That's when they could finally begin doing our labor for us.

  1. The Hellenistic world is dealt with in many places. For a fine introduction see: S. B. Clough, N. G. Garsoian, and D. L. Hicks, A History of the Western World: Ancient and Medieval. (Boston: D. C. Heath and Company, 1964): II The Classical World, 1. The Hellenistic World.
  2. For some of what little has been written on Maria, see: R. P. Multhauf, The Origins of Chemistry. (New York: Franklin Watts, Inc., 1966); F. S. Taylor, The Alchemists. (New York: Arno Press, 1974); and R. Federmann, The Royal Art of Alchemy. (tr. by Richard H. Weber), (Philadelphia: Chilton Book Co., 1964
  3. For medieval steam devices, see: L. White, Jr., Medieval Technology and Social Change. (New York: Oxford University Press, 1966): Chapter III.