By Pat Lowinger
Hero (Heron) of Alexandria was a well-known mathematician and engineer of the 1st century AD. Many people are aware of some, if not several, of his ancient inventions which relied upon the use of steam power to achieve mechanical movement. By trial and undoubtedly error, Hero devised grand displays of automated movement and music to the bewildered crowds of ancient Alexandria. For some of his inventions Hero would receive public praise and notoriety, others would remain secret- a grand mystery to be exploited by a select group of ancient Greco-Egyptian priests and temple workers.
The Theory of Pneumatics
Hero is traditionally credited as the founder of the field of pneumatics or more simply the study of gases and the properties they exhibit when heated and then cooled or vice versa. Many of our modern conveniences and machines are based on the application of pneumatics. Those who have seen a steam locomotive in action or heard the hissing of air-breaks on a modern semi-truck likely don’t ever take a few brief moments to silently offer thanks to Hero or his pioneering work, but perhaps they should…
Modern historians, engineers and scientists are fortunate that some of Hero’s written works have survived and are available to us today. One of Hero’s surviving works, Pnuematica, details the early principles of gas (air) theory and the creation of vacuums within closed systems. Perhaps Hero’s best known inventions was the aeolipile, or basic steam engine, which utilized steam pressure to spin (rotate) a sphere around a fixed axis. In addition to pnuematics, Hero typically incorporated hydraulics, pulleys and gears into many of his inventions, demonstrating his advanced knowledge of science which was previously unrivaled in the ancient world.
The Magical Doors
In order to help the gods amaze their faithful worshipers, Hero designed an elaborate set of temple doors which would appear to open without the aid of person or mechanism. As believers neared the temple the doors would be closed. As worshipers gathered, the priest would begin ‘divine’ incantations and light a sacred fire. This fire was positioned over a a metallic vessel containing water which would be heated as the ritual progressed and prayers to the gods were offered by the priest and possibly the worshipers in attendance. When enough steam had been generated, the doors which had been built upon ‘mechanical hinges’ would open.
As Hero experimented and further refined his inventions, additional ‘features’ could be added to his devices. By adding an additional system of gears, pulleys and partially filled (sealed) container of water, Hero could combine the opening of the temple door to the sounding of a trumpet. As the door opened, the lower portion of a specially designed trumpet containing a reservoir of trapped air would be lowered (submerged) into the water-filled vessel. The resulting pressure would force air up and through the trumpet, creating a musical tone (of unknown tonal quality).
To the faithful worshipers, this was a divine pronouncement by the gods that the prayer (sacrifice) offered on their behalf had been accepted. For the priests, this was a way to inspire continued patronage and contributions to the temple which they faithfully served. For Hero, this was simply the application of science and an expedient way for him to not only test his various theories, but also to provide him with considerable financial support. Hero’s own complicity as a co-conspirator in these acts of charlatanism seems rather obvious, but in the ancient world the line separating science from mysticism was often unclear. An occurrence we can still observe today in our analysis of religious and metaphysical beliefs.
Hero’s Musical Birds
Another of Hero’s creations was his ‘magical’ singing birds. By the clever use of a fountain of water, Hero was able to bring his metallic birds to life. By pouring water into the air-tight container (altar or pedestal), air was forced up and through a tube which caused ‘the bird’ to ‘sing.’ Depending on the scale desired, a larger pedestal could be constructed and by adjusting the number of birds and/or volume of water poured into the pedestal, flocks of ‘singing birds’ could be brought to life. Hero’s writings also explain that by varying the size and quality of the pipes, that different notes (tones) could be created- as well as incorporating various ‘automations’ or mechanical movements, giving even more wonder and splendor to his creations.
The Coin Machine
Perhaps not the most ingenious of Hero’s inventions, the ‘coin machine’ was perhaps the most lucrative. This was Hero’s answer for an otherwise busy and occupied priest who did not have the time necessary to take donations from the multitudes of temple patrons who wanted to make small monetary sacrifices in exchange for ‘divine’ blessings.
Upon entering the temple, a patron would approach a statute of their beloved god or goddess. After offering a short prayer or a few moments of silent reflection, they would place a coin (of five drachms) into a slot located on the top a vessel (appearing as a sealed vase). The weight of this coin would cause a lever to be raised and a small amount of ‘sacred’ water (or wine) contained within the vessel would be poured out. When the weight of the coin had depressed the level to a certain point (and released the prerequisite amount of liquid), the coin would ‘fall’ into the vessel, releasing the arm and shutting off the flow of liquid. The water or wine could then be used in whatever manner desired to insure continued blessings from the gods. Again, this was a miracle to those who had little or no understanding of machines or science in the ancient world, but could be considered rather simple by today’s standards. In some respects, Hero’s coin machine was the ancient equivalent of an automated horoscope or tarot card reader.
Discussion and Conclusion
As a pioneer in the field of pneumatics Hero’s contribution to ancient science were revolutionary and inspiring to modern historians, physicists and science enthusiasts alike. In Pneumatica, Hero describes no less than 78 ‘inventions’ which could be utilized for various tasks or as displays of wonderment. Of those 78, 10 were specifically created for ‘use’ in the temples of Alexandria and beyond. Of the remaining 68, most could have been easily incorporated into one or more rituals or divine mysteries presented by priests to amaze and astound the temple’s patrons.
As modern people we might view Hero of Alexandria as little more than an elitist who made a living by bilking the simple and gullible people of Alexandria. This opinion is not without some merit. As for myself, I see Hero as a much more socially complex and fascinating person than this. Through his inventions, Hero offered the people of Alexandria a tangible connection to the divine as well as amazing and wonderful displays of science- admittedly without full disclosure. It can be easy to dismiss this assertion, or is it? Are Hero’s inventions any different than modern faith healers and televangelists who will ‘cure’ or ‘save’ someone in exchange for a small ‘faith donation.’ For only $2 a minute, you too can have your own personal psychic reading done by ‘trained and certified’ psychics.
I would encourage anyone with an interest in Hero’s story and/or his considerable inventions to read one of more of the current literary works which discuss his story in detail, such as The Rise and Fall of Alexandria: Birthplace of the Modern World by Justin Pollard and Howard Reid, paying special attention to chapter 12.
The Pneumatics of Hero of Alexandria translated by Bennet Woodcroft (1851), originally published via University College, London.
Available digitally via the Hopkin Thomas Project, University of Rochester: http://himedo.net/TheHopkinThomasProject/TimeLine/Wales/Steam/URochesterCollection/Hero/index-2.html