In existographies, Hero (c.10-70AD) (IQ:185|#63) [RGM:310|1,500+] (EP:3) [GEE:#] (Eells 100:36) [CR:63], aka "Heron" or "Hero of Alexandria", was a Greek physicist, engineer, and mathematician, noted for a number of things, such as his circa 50AD Pneumatics, variously titled as Inventions of the Ancients (Clark, 1885) or Spiritalia seu Pneumatica (Thurston, 1878), wherein, in his overview of the physics of Strato and Ctesibius, he outlines an atomic theory in which matter consists of particles mixed with distributed vacua, and in which he describes 78 propositions or devices, e.g. how to make an aeolipile, among other heat-powered devices, some of which he says are his own invention, others being handed down to him by the ancients. [1]

In 50AD, Hero, published his Pneumatics, cataloging of various pneumatic-like machines, invented by others before him, others invented by him, although this is not stated explicitly.

In the twelfth and thirteenth century, Hero’s book began to be century the book began to be translated into various languages, such as in Sicily, under titles such as: The Curious Art of Spirit Movement (The Artificiosi et Curious Spiritual Movements) (Commandino, 1575), or Inventions of the Ancients (Clark, 1885), Spiritalia seu Pneumatica (Thurston, 1878).

It is also said that Hero may have used a type of Philo thermometer (240BC) in his experimental work.

Hero device 57 (Syringe)
A depiction of Hero's device 57, a syringe, in which he says when handle EF is withdrawn, a vacuum is produced, according to which liquid can be sucked in, via tube GH.
One horsepower pump
The following shows a four-cylinder one-horsepower pump, which, supposedly, is found in one of Hero's 1589 Spiritalia reprints, which illustrates the transformation of rotary motion to reciprocating motion via gears: [11]

Hero one horsepower pump

Device 57 | Syringe
Here, in his device #57, described the operation of the syringe, which he says can be employed for either suction or injection:

“The instrument called a ‘pyulcus’ acts on the same principle. A hollow tube, of some length, is made, A B (fig. 57); into this another tube, C D, is nicely fitted, to the extremity C of which is fastened a small plate or piston, and at D is a handle, E, F. Cover the orifice A of the tube A B with a plate in which an extremely fine tube, G H, is fixed, its bore communicating with A B through the plate. When we desire to draw forth any pus, we must apply the extreme orifice of the small tube, H, to the part in which the matter is, and draw the tube C D outwards by means of the handle. As a ‘vacuum’ is thus produced in A B something else must enter to fill it, and as there is no other passage but through the mouth of the small tube, we shall of necessity draw up through this any fluid that may be near. Again, when we wish to inject any liquid, we place it in the tube A B, and, taking hold of E F, depress the tube C D, and force down the liquid until we think the injection is effected.’


Hero device 47
An illustration of Hero's device 47 entitled “A Fountain which trickles by the Action of the Sun's Rays”. [8]
Device 47 | Solar-powered Trickle Fountain
The device #47, titled “A Fountain which trickles by the Action of the Sun's Rays”, of Hero’s listing of the inventions of the ancients, as illustrated adjacent, operates as follows:

“The ‘fountain’ as it is called may be made to trickle as long as the sun falls upon it. Let there be an airtight pedestal, ABCD (adjacent), through which a funnel is inserted, its tube extending within a very little of the bottom. Let E F be a globe, from which a tube leads into the pedestal, reaching nearly to the bottom of the pedestal and to the circumference of the globe, while a bent siphon, fitted into the globe, leads into the funnel. Now pour water into the globe; and when the sun falls upon the globe, the air in it, being heated, will drive out the liquid, which will be carried along the siphon G, and pass through the funnel into the pedestal. But when the globe is in the shade, the air having escaped through the globe, the tube will again suck up the liquid, and fill the void which had been produced; and this will take place as often as the sun falls upon the globe.”

This model was modified by Giovanni Porta (1606) and or Salomon de Caus (1615) wherein fire heat was employed instead of solar heat to make a water raising device; one recounting of this is:

“Hero's forty-seventh invention, is designed for the heat of the sun to expand the water in A, and by compressing the air on its surface jointly with the vapor formed, to force the contents in A up the pipe B. When A is cooled, the water in D would rise to fill the partial vacuum in A, and be emptied as before. By substituting a fire below A, instead of the sun above it, we have a simple water-raising engine on De Cans's plan.”


Hero (device 37)
A depiction of Hero's device 37, a heat engine for opening temple doors. [6]
Device 37 | Door-opening heat engine
Hero, in his device #37, described as a machine for “Opening Temple Doors by Fire on an Altar”, details his method of using the expansion of the volume of air by fire to expel water into a bucket, which falls a height, which turn cylinders, which open the temple doors as follows: [6]

“The construction of a small temple such that, on lighting a fire, the doors shall open spontaneously, and shut again when the fire is extinguished. Let the proposed temple stand on a pedestal, ABCD (figure 37), on which lies a small altar, E D. Through the altar insert a tube, F G, of which the mouth F is within the altar, and the mouth G is contained in a globe, H, reaching nearly to its center: the tube must be soldered into the globe, in which a bent siphon, suspended vessel; and through a hole, p, which must be carefully closed afterwards, pour water into the globe enough to fill one half of it. It will be found that, when the fire has grown hot, the air in the altar becoming heated expands into a larger space; and, passing through the tube F G into the globe, it will drive out the liquid contained there through the siphon K L M into the suspended vessel, which, descending with its weight, will tighten the chains and open the doors. Again, when the fire is extinguished, the rarefied air will escape through the pores in the side of the globe, and the bent siphon, (the extremity of which will be immersed in the water in the suspended vessel) will draw up the liquid in the vessel in order to fill up the void left by the particles removed. When the vessel is lightened the weight suspended will preponderate and shut the doors. Some in place of water use quicksilver, as it is heavier than water and is easily disunited by fire.”

Interestingly, here we see Hero discussing, what seems to be, the existence of a vacuum made by fire. According to others, however, some have stated that Hero was said to have openly challenge the nature abhors a vacuum belief, but his attempts to create an artificial vacuum failed. [2]

The following is an alternative sketch of Hero's temple door opening heat engine:

Hero temple door heat engine

A retrospect historical note on Hero’s device 37 is as follows:

“A hot-air engine, however, which is the subject of his 37th proposition, is of real interest. Hero sketches and describes a method of opening temple-doors by the action of fire on an altar, which is an ingenious device, and contains all the elements of the machine of the Marquis of Worcester [Edward Somerset], which is generally considered the first real steam-engine, with the single and vital defect that the expanding fluid is air instead of steam.”
Robert Thurston (1878), A History of the Growth of the Steam Engine (pg. 5)

Hero, in short, seems to have been the first to invent and build a heat engine, namely a steam engine that opens temple doors, in the operation of which, fire causes water vapor to expand in a closed vessel, water is forced out, fills the adjacent bucket, and the temple door is opened by means of chains; when fire is extinguished, the process reverses and the door closes. [3]

A depiction of the aeolipile described by Hero, attached to a Joule mechanical equivalent of heat style device for measuring the work done in raising a body through a distance of height.
Device 50 | Aeolipile
Hero, in his device #50, describes the aeolipile. [6] The aeolipile device, shown below with modern annotation, is said to have been invented in circa 250BC by Greek compressed air engineer Ctesibius, and is often assigned as being the world's first prototype steam engine.

These came to be known as the ‘aeolipile’ as described by both Roman architect Vitruvius (15BC) and by Hero (50AD). [1] Owing to the fact that Hero was the first to give a detailed account on how to make an aeolipile, the device has since come to be known as Hero's engine or the aeolipile of Hero.

French physicist Denis Papin (1647-1712) who invented 1679 the pressure cooker and in 1690 published his first work on the steam engine in De novis quibusdam machinis, in which the Papin engine is described, knew the aeolipile from Hero's Pneumatica, as had been translated by Gottfried Leibniz (1646-1716), Germany. [4]

Here, in his Automata, described the workings of several bird automatons. Hero also invented many mechanisms for the Greek theater, including an entirely mechanical play almost ten minutes in length, powered by a binary-like system of ropes, knots, and simple machines operated by a rotating cylindrical cogwheel. The sound of thunder was produced by the mechanically-timed dropping of metal balls onto a hidden drum. Heron constructed a three-wheeled cart that could carry a group of automata to the front of a stage where they would perform for an audience. Power came from a falling weight that pulled on a string wrapped round the cart's drive axle. [7]

The following is a reconstruction, by by Giovanni Battista, of one of many “automata” of Heron: [4]
Hero automaton
A type of device that would later go on to serve as a type of thought experiment by deep thinkers such as Rene Decartes and John Neumann, in regards to what exactly constitutes "life" in a modern scientific or philosophical sense of the matter.
Hero (11th proposition)
The so-called "11th proposition" of Hero, namely a heat-powered animated alter described as ‘Libations on an Altar produced by Fire’, which Robert Thurston calls the "first application of heat to produce motion of fluids". [5]

Device 11 | Fire libations altar
In c.55AD, Hero, in his 11th proposition “Libations at an Altar produced by Fire”, of his Pneumatics, described fire-powered libations alter as follows: [6]

“To construct an altar such that, when a fire is raised on it, figures at the side shall offer libations. Let there be a pedestal, ABCD (see: figure) on which the figures stand, and also an altar, E F G, perfectly air-tight. The pedestal must also be air-tight, and communicate with the altar at G. Through the pedestal insert the tube H K L, reaching nearly to the bottom at L, and communicating at H with a bowl held by one of the figures. Pour liquid into the pedestal through a hole, M, which must afterwards be closed. Now if a fire be lighted on the altar E F G, the air within it, being rarefied, will descend into the pedestal, and exert pressure on the liquid it contains, which, having no other way of retreat, will pass through the tube H K L into the bowl. Thus, the figures will pour a libation, and will not cease so long as the fire remains on the altar. When the fire is extinguished, the libation ceases; and as often as the fire is kindled the same will be repeated. The pipe through which the heat is to pass should be broader towards the middle, for it is requisite that the heat, or rather the vapor from it, passing into a broader space, should expand and act with greater force.”

The following is related commentary on this Hero device #11:

“The 11th proposition of Hero, namely: ‘Libations on an Altar produced by Fire’, is the first application of heat to produce motion of fluids. This toy embodies the essential principle of all modern heat-engines—the change of energy from the form known as heat-energy into mechanical energy, or work. It is not at all improbable that this prototype of the modern wonder-working machine may have been known centuries before the time of Hero.”
Robert Thurston (1878), A History of the Growth of the Steam Engine (pg. 5) [1]


1. (a) Hero. (c.55AD). Pneumatics (translator: Bennet Woodcroft). Taylor, 1851.
(b) Philo (c.55BC). Pneumatica: the first Treatise on Experimental Physics (Hero, Pneumatica, 16+ pgs). Publisher.
(c) Eells, Walter C. (1962). “100 Greatest Mathematicians of All Time” (Ѻ), Mathematics Teacher, 7(55).
2. Genz, Henning (1994). Nothingness, the Science of Empty Space (translated from German by Karin Heusch ed.). New York: Perseus Book Publishing (published 1999).
3. Gebelein, Helmut. (2002). “Alchemy and Chemistry in the Work of Goethe” (Heron of Alexandria, pgs. 11-12), In: The Golden Egg: Alchemy in Art and Literature, pgs. 9-30. Galda & Wilch.
4. Lahanas, Michael. (c.2010). “Heron of Alexandra”,
5. (a) Hero. (c.55AD). Pneumatics (translator: Bennet Woodcroft). Taylor, 1851.
(b) Thurston, Robert H. (1878). A History of the Growth of the Steam-Engine (Ch. 7: "The Philosophy of the Steam Engine: Energetics and Thermo-Dynamics) (pg. 5). D. Appleton and Company.
6. Hero. (c.55AD). Pneumatics (translator: Bennet Woodcroft). Taylor, 1851.
7. Hero –
8. Clark, Daniel. (1885). An Elementary Treatise on Steam and the Steam-Engine, Stationary and Portable: an Extension of the Elementary Treatise on Steam of John Sewell (pg. 5). Crosby.
9. Boas, Marie. (1949). The Mechanical Philosophy (pg. 546). Publisher.
10. Kirby, Richard; Withington, Sidney; Darling, Arthur; and Kilgour, Frederick. (1956). Engineering in History (pg. 154). Courier, 1990.
11. (a) Hero. (1589). Spiritalia. Publisher.
(b) Author. (1920). “Article” (Ѻ), Transactions of the Newcomen Society, Volume 16, Date.
(c) Kirby, Richard; Withington, Sidney; Darling, Arthur; and Kilgour, Frederick. (1956). Engineering in History (pg. 166). Courier, 1990.

Further reading
● Hero. (c.55AD). On Pneumatical Spirits (Spiritalia seu Pneumatica). Publisher.
● Hero. (c.55AD). Pneumatics (translator: Bennet Woodcroft). Taylor, 1851.

External links
Hero of Alexandria – Wikipedia.

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