As I explained at the very beginning of this series the Greek concept ta physika was very different from what we envision when we hear the word physics today. In fact, this series is an attempt to sketch the path from the ta physika of Greek antiquity to the emergence of our modern physics in the Early Modern Period. We can find fragments of the roots of physics is various different areas of thought in antiquity and I have already looked at the philosophers, the mathematicians, the astronomers, ancient Greek optics, and statics. Today, I will turn my attention to the engineers, which means basically the first century BCE Roman architect, Vitruvius (c. 75–after c. 15 BCE)
and the first century CE Greek engineer and mathematician, Hero of Alexandria (fl. 60 CE).
Although there are other aspects to their work the principal reason for including them is their work on machines, as I pointed out in the last episode, mechanics comes from study of machines.
Greek μηχανική mēkhanikḗ, lit. “of machines” and in antiquity it is literally the discipline of the so-called simple machines: lever, wheel and axel, pulley, balance, inclined plane, wedge, and screw.
As I explained in my series on Renaissance Science the re-emergence of the works of Vitruvius and Hero in the Renaissance triggered a whole culture of artist engineers and of machine books, both of which played a significant role in the cross over between the theoretical book knowledge of the scholastics and the practical knowledge of the artisans or better said the dissolving of the boundary between them creating a meld between the two types of knowledge that would over the next two and a half centuries lead to the modern concept of knowledge or science. Whereas the early knowledge of machines consisted of how they function and how to construct them, the emerging modern physics explained why they work.
Both Vitruvius and Hero of Alexandria were building on a long tradition of machine building Ancient Greek engineers, most of whose work has not survived but who are referenced by later authors such as Vitruvius, Hero, and Pliny. We have the fourth century BCE military engineer Polyidus of Thessaly, who served under Philip II of Macedon (382–336) and his two students Diades of Pella and Charias, all three of whom are referenced by Vitruvius in his own section on siege engines in Book X of De architectura.
They are also included in a list of “those who have written about machines” in the preface to Book VII on Finishing:
…those who have written about machines like Diades, Archytas, Archimedes, Ctesibios, Nymphodoros, Philo of Byzantium, Diphilos, Democles, Charias, Polyidos, Pyrrhos, and Agesistratos.
Taken from Vitruvius Ten Books on Architecture Ed. Ingrid D Rowland & Thomas Nobel Howe
Nymphodoros, Diphilos, and Democles are not otherwise known. Pyrrhos (318–272 BCE), King of Epirus, was a renowned military strategist, who wrote a thesis on siegecraft.
I have a separate post on Archimedes (c. 287–c. 212 BCE), who is without doubt the most well-known engineer in antiquity. Archytas (c. 420–c. 355 BCE) was a mathematician associated with the Pythagoreans. He is thought to have been a pupil of the Pythagorean, Philolaus (c. 470–c. 385 BCE) and to have been the teacher of Eudoxus of Cnidus (c. 390–c. 340 BCE). Like many figures in antiquity much was written about him but none of his own writings have survived. He is credited with the creation of the concept of the quadrivium–arithmetic, geometry, music, astronomy–which became the basis of mathematical education first on the Latin schools and later the universities in the Middle Ages. Vitruvius’ Book X Chapters 13, 14, and 15 are almost identical to chapters on siegecraft from the Περὶ μηχανημάτων Perì mēchanēmátōn (On Machines) by Athenaeus Mechanicus (fl. mid-to-late 1st century BCE) and the, no longer extant book, of Agesistratos (late 2nd century BCE), about whom almost nothing in known, is thought to be the common source.
This just leaves Ctesibios and Philo of Byzantium from Vitruvius’ list. Ctesibios (fl. 285–222 BCE) wrote extensively on compressed air, i.e. pneumatics, but none of his work survives. However, he is referenced by Athenaeus, Vitruvius, Pliny, Proclus, and Philo of Byzantium.
Philo of Byzantium (c. 280–c. 220 BCE), also known as Philo Mechanicus, only gets referenced by Vitruvius, Hero, and the mathematician Eutocius of Ascalon (c. 480s–c. 520s CE), who discussed his method for doubling a cube. Almost nothing is known about him, other than that he spent most of his life in Alexandria. He left only one known work is an encyclopaedic book on mechanics the Syntaxis (Μηχανική Σύνταξη, Mēkhanikḗ Sýntaxē). This only survives in fragments, but internal references allow us to recreate the titles of all nine sections:
- Isagoge (Εἰσαγωγή, Eisagōgḗ) – Introduction (general mathematics)
- Mochlica (Μοχλικά, Mokhliká) – Leverage (mechanics)
- Limenopoeica (Λιμενοποιικά, Limenopoiiká) – Harbour Construction
- Belopoeica (Βελοποιικά, Belopoiiká) – Siege Engine Construction
- Pneumatica (Πνευματικά, Pneumatiká) – Pneumatics
- Automatopoeica (Αὐτοματοποιητικά, Automatopoiētiká) – Automatons (mechanical toys and diversions)
- Parasceuastica (Παρασκευαστικά, Paraskeuastiká) – Preparations (for sieges)
- Poliorcetica (Πολιορκητικά, Poliorkētiká) – Siegecraft
- Peri Epistolon (Περὶ Ἐπιστολῶν, Perì Epistolō̂n) – On Letters (coding and hidden letters for military use)
Belopoeica, Parasceuastica, and Poliorcetica are extant in Greek, as are fragments of Isagoge and Automatopoeica. For a long time only the first sixteen chapters of Pneumatica were known in a Latin translation of an Arabic text but in the early twentieth century three new fuller Arabic manuscripts were found, one in the Bodleian and two in the library of the Hagia Sophia.
As can be seen Vitruvius and Hero are part of a tradition of Greek mechanics that extends over more than five centuries but it is only with the two of them that we have complete books that were rediscovered, translated, and printed in the Early Modern Period, contributing significantly to the practical turn that was an important feature of the emergence of modern science.
Once again with Vitruvius, we have a figure from antiquity about whom we know very little. He seems to have worked in some capacity for Julius Caesar (100–44 BCE) and as a military engineer for Caesar’s grandnephew and adopted heir, Gaius Octavius (63 BCE–14 CE), later the Emperor Augustus. Upon retirement he came under the patronage of Augustus’ sister Octavia Minor (c. 66–11 BCE).
He is, of course, renowned as the author of De Architectura Libri Decem, (Ten Books on Architecture), which is actually a description not a title, signifying ten parchment scrolls on the subject of architecture. As with the Elements of Euclid, there is a discussion as to whether Vitruvius actually wrote all ten books or merely brought together and edited the contents produced by several authors. The ten books are:
- Book 1: First Principles and the Layout of Cities
- Book 2: Building Materials
- Book 3: Temples
- Book 4: Corinthian, Doric, and Tuscan Temples
- Book 5: Public Buildings
- Book 6: Private Buildings
- Book 7: Finishing
- Book 8: Water
- Book 9: Astronomy, Sundials and Clocks
- Book 10: Machines
Viewed from our standpoint a peculiar mixture of themes but in antiquity there existed no division between architecture and mechanical engineering. In fact, service as a military engineer, like Vitruvius, was one of the two available sources for architectural training. The other was an apprenticeship as a builder. Although this seems strange to us now, we should remember that Leon Battista Alberti (1404–1472), who wrote the first architectural treatise in the Renaissance, De re aedificatoria (On the Art of Building) based on Vitruvius, written between 1443 and 1452 but published in 1485 as the first printed book on architecture, was a mathematician, who considered mathematics as the foundation of the arts and the sciences. Also following the Great Fire of London in 1666, the two architects who rebuilt London were Christopher Wren (1632–1723), astronomer, mathematician and physicist, and Robert Hooke (1635–1703), a polymath, who was predominantly a physicist Neither of them was a trained architect.
Of the ten books, it is the last three that in the Early modern period had an influence on the emergence of physics. Book 8, which deals with the practical side of water supplies is in some respects a treatise on applied hydrostatics.
Book 9 deals with time a central theme in physics and the water clocks that he describes also, like parts of Book 8, an application of hydrostatics, with the more complex ones also involving the construction of machines.
It is Book 10 he opens up the full panoply of mechanics, the construction of machines. We find pully systems, cranes for building sites, cranes for ships and harbours, methods for hauling large blocks, winches, water wheels, bucket chains, the water screw, water pumps, hydraulic organs, hodometers (a mileometer) on land and on water, and to close a wide range of military weapons and siege engines. All of these machines are on a theoretical level examples of applied physics and explaining how and why they worked in terms of forces was a natural consequence of the Renaissance machine culture that Vitruvius’s book helped to inspire.
Included amongst Vitruvius’ machines is the toy steam engine, the aeolipile, which is most commonly associated with Hero of Alexandria to whom we now turn.
Unlike Philo of Byzantium and Vitruvius, who each only wrote one book, Hero left us with several works and that is all that he left us. As one source put it, apart from his works we know nothing at all about him. The earliest mention of his works is by Pappus around 300 CE and he himself quotes Archimedes making c. 250 BCE another terminus. He has been dated from 150 BCE to 250 CE, but Otto Neugebauer demonstrated that a lunar eclipse that Hero describes, in his Dioptra, having observed took place in 62 CE, hence flourished c. 60 CE.
Hero was a mathematician and an engineer and based on his texts he is judged by historians to have been a practical man rather than a scholar, although some of his texts appear to be the lectures of a teacher. His work also shows him to have carried out much in the way of experiments. His surviving works are:
- Pneumatica (Πνευματικά), a description of machines working on air, steam or water pressure, including the hydraulis or water organ
- Automata, a description of machines which enable wonders in banquets and possibly also theatrical contexts by mechanical or pneumatical means (e.g. automatic opening or closing of temple doors, statues that pour wine and milk, etc.)
- Mechanica, preserved only in Arabic, written for architects, containing means to lift heavy objects
- Metrica, a description of how to calculate surfaces and volumes of diverse objects
- On the Dioptra, a collection of methods to measure lengths, a work in which the odimeter and the dioptra, an apparatus which resembles the theodolite, are described
- Belopoeica, a description of war machines
- Catoptrica, about the progression of light, reflection, and the use of mirrors
There are other works attributed to him, but the attributions are considered doubtful. As can be seen, apart from the Catoptics, which I dealt with separately in the episode on optics, his surviving work covers much of the same territory as the mechanical chapters of Vitruvius Like Vitruvius, Hero was a major influence on the evolution of the anti-scholastic scientific thought, when his texts became known in the Early Modern Period.