sign in sign up
<<
Home , Ancient Greek technology, Ctesibius, Lever, Of Alexandria, Philon, Pulley

Proceedings of the European Control Conference 2007 TuA07.4 Kos, , July 2-5, 2007

Technology and Autonomous Mechanisms in the Mediterranean: From to

K. P. Valavanis, G. J. Vachtsevanos, P. J. Antsaklis

Abstract – The paper aims at presenting each period are then provided followed by and automation advances in the accomplishments in automatic control and the World, offering evidence that transition from the ancient Greek world to the Greco- feedback control as a discipline dates back more Roman era and the Byzantium. than twenty five centuries. II. CHRONOLOGICAL MAP OF SCIENCE & TECHNOLOGY I. INTRODUCTION It is worth noting that there was an initial phase of The paper objective is to present historical evidence imported influences in the development of ancient of achievements in science, technology and the Greek technology that reached the Greek states from making of automation in the ancient Greek world until the East (Persia, Babylon and Mesopotamia) and th the era of Byzantium and that the main driving practiced by the Greeks up until the 6 century B.C. It behind Greek science [16] - [18] has been curiosity and was at the time of Thales of (circa 585 B.C.), desire for knowledge followed by the study of nature. when a very significant change occurred. A new and When focusing on the discipline of feedback control, exclusively Greek activity began to dominate any James Watt’s Flyball Governor (1769) may be inherited technology, called science. In subsequent considered as one of the earliest feedback control centuries, technology itself became more productive, devices of the modern era. As demands on the device and technological innovations surfaced through grew, the flyball governor was required to work in new synergies between science and technology. New operating regions where it was exhibiting undesirable measuring instruments, geometrical concepts, oscillations for unexplained reasons at that time. It was , mechanics, musical instruments, J. C. Maxwell (1868) who first used differential influenced important application domains like equations to model and explain this phenomenon, and metallurgy, construction projects, architecture, military this event marked the beginning of the introduction of tactics and , among others [16] - [18]. th mathematical rigor into the study of feedback control One of the first inventions of the 5 century B.C., not devices, together with the work of Routh (1877) and widely known but very important, was the starting Lyapunov (1890) [5] - [13]. in ancient stadiums, built to prevent However, the discipline of feedback control has a untimely starts in races, called ‘hysplex’ (in Greek very long history dating back over twenty centuries. !"#$%&), shown in Figure 1. Quoting from [14, pp. 465- Looking back, one finds that automatic feedback 472], “The system consisted of two horizontal ropes control devices appeared first in the work of Ktesibius stretched in front of the waist and the knees of the (or ) of (circa 270 B.C.) as runners. The ends of the ropes were tied at the peaks reported by (circa 25 A.D.), Heron (or Hero) of vertical wooden posts implanted in mechanisms (circa 60 A.D.) and of Byzantium near the two ends of the starting threshold. The (circa 230 B.C.). In fact, the first feedback control mechanisms were controlled by the starter, who, device on historical record is the water of standing at the back of the runners, could let at the Ktesibius [5], [6]. appropriate moment the ropes to fall down, thus Indeed, the roots of automation, automated permitting all the runners to start simultaneously” [20]. mechanisms, and feedback control are found about In terms of chronological accomplishments and 3,000 years ago, and they are centered in the ancient breakthroughs, the era of ancient Greek science is Greek world that developed in the Mediterranean divided into four major periods [16], [21]: i) The pre- th region. A foundation is first provided by sketching the Socratic period from 600 B.C. to about 400 B.C. ii) 4 map of the Mediterranean region and the ancient century B.C. (400-300) with main representatives Greek world in terms of science and technology and its , , the Epicureans and Stoic philosophers. major contributors. Details of achievements during iii) The Hellenistic (in Greek '$$%()"*)+,) period, 300- 100 B.C. with main representatives , K. P. Valavanis is with the University of South Florida , Apollonius. This has been coined as the ([email protected],edu), G. J. Vachtsevanos is with the Georgia Institute of Golden Era of science and technology. It was the Technology ([email protected]), and P. J. Antsaklis is with Notre Dame period that followed the death of , University ([email protected]). Prof. Valavanis is the corresponding author. 323 B.C., where Alexander’s successors ruled most of

ISBN: 978-960-89028-5-5 263 TuA07.4

the so called Old World. During that period more direct of undertaking empirical research ( and interaction took place between the Greek and Aristotle). remnants of older cultures. iv) 100 B.C.–600 A.D., Thales is mostly known as the first person who where Greek science was influenced by spiritual and studied geometric objects, circles, lines, triangles. He non rational currents that were partially responsible for was the first who thought of the as a separate, the rise of Christianity. It was during that period that distinct and autonomous mathematical entity, and he Greek science passed later on to the Arabs and to the established it as the fourth geometric element Latin West was epitomized, reorganized and subjected complementing the other three, length, surface, to extensive commentaries. volume. Thales’ contribution to science is that his work as a discipline was tightly coupled with never referred to calculations and results obtained for a technological achievements. Mathematics was used specific example or case study (as the Egyptians and not only as a theoretical discipline but also as a ; the Babylonians did), but rather, it was very general; he mathematics was behind a wide range of applications is considered to be the first theoretician in the field of and the means to engineering designs. It is no mathematics with theorem proving abilities. coincidence that Thales, , Euclid, Focusing on mechanisms, technological innovation Archimedes, and Apollonius were at was either related to invention of machines functioning first. Archimedes was the first one to utilize using external means such as, animal or wind power, mathematics in a completely mature fashion for the or related to invention of automatic devices moving by treatment of a physical problem. Furthermore, the themselves without requiring any human force; such tradition of formal mechanical treatises, including were the inventions of Heron of Alexandria as detailed theoretical and applied mechanics, as distinct domains below. from the almost completely theoretical mechanics of One of the oldest mechanisms chronicled around Archimedes continued in the 3rd century B.C. by 580 B.C., depicting an oil press operated by the weight Ktesibius whose work, although lost, is known only of stones was found by Fouque in 1879 in Therassia, a through the references of Vitruvius and by Philon of small island opposite Thera (Santorini). The only Byzantium. The most comprehensive of the extant evidence found on an ancient Greek design is on mechanical treatises is that of Heron of Alexandria, a exhibit at the British museum in London. recognized and an excellent mechanic. It is documented that the first major breakthrough contribution to autonomous mechanisms occurred III. ANCIENT GREEK SCIENCE & TECHNOLOGY during the era of Pythagoras (who was Thales’ student There were three main institutions in the ancient for a few years). It is attributed to the Pythagoreans Greek world that contributed to science and and in particular to from the city of Tarantas technology: Plato’s Academy, Aristotle’s Lyceum, and (in south ), known as Archytas the Tarantine (also The . Plato’s Academy and referred to as Leonardo da Vinci of the ancient world). Aristotle’s Lyceum were focusing more on science; Archytas was not only the inventor of the number ‘one’, they were very influential institutions operating as 1 (the father of 1) in number theory, but he also was Schools or Universities charging tuition, and financially the first engineer. By applying a series of geometric self sustained. The museum and Library of Alexandria notions and observations to the study of structures, established around 300 B.C. exerted long lasting links and joints, he created Mechanics (in Greek influence over many centuries; it was operating more -%./()+,)! Not only he was drawing mechanisms, he like a research laboratory than a University and it was was also building them. As such, in 425 B.C. he financially dependent on the rulers of [16] - [18], created the first Unmanned Aerial of all times [22]. by building a mechanical bird, a pigeon that could fly Among the earliest contributors to ancient Greek by moving its wings getting energy from a mechanism science and technology were the members of the in its stomach. This flying flew about 200 Miletian School and particularly . The meters. However, once all energy was used, the main contributions of the Miletian School were pigeon fell, landed, on earth and could not fly, take off, considered to be the distinction between the natural again. and the supernatural and the introduction of rational The introduction of catapults changed the art of war. criticism and debate. Achievements of the period The first catapults appeared in Syracuse, during the between Thales and Aristotle were the advances in time of the Dionysius the Elder (Dionysius of factual knowledge (anatomy, zoology), the problem Syracuse, 430 – 367 B.C.), who created the first ever formulation (Aristotle’s biological problems of scientific research center [2]. The widest and most well reproduction and heredity), the application of known use of catapults occurred during the reign of mathematics to the understanding of natural Philip of and his son Alexander the Great phenomena (Pythagoreans and Plato) and the notion who perfected the use of catapults to gain advantage in battles against their enemies. Perfection was the

264 TuA07.4

elaboration of mathematical formulas that related the technology and their writings were reprinted until the size of the catapults’ components to the weight of the 16th century A.D. projectiles or the size of the bolts that were about to Ktesibius (circa 270 B.C.) was a Greek physicist and shoot by the Alexandrian mechanics [14, pp. 545-548]. inventor, the first great figure of the ancient Figure 2 illustrates two types of catapult that subverted engineering tradition of the School of Alexandria. The martial tactics and dominated for many centuries the discovery of the elasticity of air is attributed to him, as battlefield; Figure 3 depicts reproduced designs by N. is the invention of several devices using compressed Orfanoudakis of other types of catapults; a catapult air, including force and an air powered catapult. used to throw ‘Greek fire’ and the theoretical design of His most famous invention, however, was an a portable mechanism to throw ‘Greek fire’, composed improvement of the clepsydra (in Greek +$23!45/), or of pipes coupled with a tormentum serving as a power , in which water dripping at a constant rate source. Similar mechanisms are shown in Figure 4. raised a float that held a pointer to mark time (the Several inventions are attributed to Archimedes, passage of hours). Another notable invention was a who, according to Drachmann, was “…the greatest ‘hydraulis’, or , in which air was forced mathematical and engineering genius of ancient times” through the organ pipes by the weight of water rather [14], [23], [24]. He was perhaps the first to use than by falling lead weights [18] - [20]. Unfortunately, mathematics to solve physical problems. Figure 5 Ktesibius' writings have not survived, and his shows Leonardo da Vinci’s drawing for the inventions are known only from references by Vitruvius ‘architronito’, the steam gun invented by Archimedes [19] and Heron of Alexandria. Figures 8 to 10 illustrate and its modern reproduction by J. G. Sakas in 1981 inventions made by Ktesibius. Ktesibius’ water clock, [27], and Figure 6 illustrates the endless . Other shown in Figure 9, incorporated a feedback inventions by Archimedes include cranes and solar mechanism that used a floating device as both a mirrors. The steam gun created the foundation for the sensor and that kept the water level theory of hydrodynamics. Information about the steam approximately constant and ensured constant flow of gun is due to the Italian Petrarca (1304-1374 A.D.), but water and so accurate time keeping [5], [6]. This it was Leonardo da Vinci who explained its operation device was so successful that it was still used in and stated that it could through a bullet weighted 1 Baghdad in 1200 A.D. when the Mongols conquered *0$/(*1 about 1,100 meters away. the city! Another invention attributed to Archimedes is the Philon of Byzantium (circa 230 B.C.) authored water clock, shown in Figure 7 that stood tall more than several books (most of which have survived) on , 4 meters (although there are researchers claiming that water , pneumatic mechanisms and military it was invented by Heron or Philon, and others). As machines, among others. His major contribution relates stated in [24], there are three sources from Vitruvius, to the subject of spur (in Greek 141(*1*16 Pappos the Alexandrian and an Arabic document that *51.16). The transfer of mechanical power and the provide evidence regarding this invention by multiplying or dividing effect of circular motion Archimedes, as reproduced by the German scientists machines are based on such gears. Philon’s treatise Wiedemann and Hauser. It is important to state that it Pneumatica is addressing key physical properties of looks like there was progress in this area before liquids and gases supported by a plethora of Ktesibius invented his water clock (see below) without experiments. He also had advanced knowledge of knowing exactly when it started. But since Archimedes metallurgy. Philon explained thoroughly Ktesibius' (287-212 B.C.) and Ktesibius (285-222 B.C.) lived contention regarding the replacement of animal fibers almost at the same time, it may be that either Ktesibius with thermally treated metal leaves. In essence, Philon improved Archimedes’ clock, or the two invented it advanced further the Alexandrian School's independently of each other. developments in automatic mechanisms started by Ktesibius. The Arabic translation of Philon’s The School of Alexandria Pneumatica is a thesaurus of such automatic devices During the golden era of the School of Alexandria based on properties of air, liquids, fire, floaters and [22], Greek thought evolved towards what Newton gears. They offer a rich foundation for a new called Natural Philosophy. This turn of Greek thought technology, automation. Although he did not complete culminates in the search for observation, his work, he laid the groundwork for the European measurements, design and construction. The School of technological developments for the next 1500 years Alexandria is directly linked with three Greek engineers [18]. of the Hellenistic world: Ktesibius, Philon of Byzantine Eight hundred years of tradition in ancient Greek and Heron of Alexandria who lived in the second science and technology culminated with the enormous century B.C. through the first century A.D. Their work of Heron who was a scientist of great breadth. contributions influenced western science and Heron of Alexandria (circa 60 A.D.) taught at the museum of Alexandria and presented in his books

265 TuA07.4

About Pneumatica and About Automation (in Greek Heron’s book The Belopoeica ( of War) A7*1µ/*1#1)%*)+,) the up until then known knowledge purports to be based on a work by Ktesibius. His three of automation . Among his surviving books on Mechanics (in Greek -%./()+,) survived in a writings, his book on automation according to somewhat altered Arabic translation. Mechanics is historians, lays the foundation of modern automatic closely based on the work of Archimedes, presenting a control and it is the oldest known document that wide range of engineering principles, including a theory describes mechanical automatic systems capable of of motion, a theory of balance, methods of lifting and performing programmed movements. [18], [20], [25]. transporting heavy objects with mechanical devices, A7*1µ/*1#1)%*)+, refers to automatic machines that and how to calculate the center of gravity for various operate and move without human intervention by simple shapes. Both books include Heron's solution to capitalizing on properties of steam, liquid and gaseous the problem of two mean proportionals, two quantities, matter, and involve complex mechanical systems and x and y that satisfy a/x = x/y = y/b, with a, b known. ingenious programming of movements. Every This may be used to solve the problem of constructing mechanical device was broken down to its constituent a cube with double the volume of a given one. components which, in turn, refer to levers with a basic A catalogue of 60 mechanical devices is attributed to geometric interpretation. Therefore, a methodology Heron, not mythical but historical and indeed was pursued although the ultimate objective of Heron’s functional, as proven by their modern reproductions. books was applications. The function of his devices was based on scientific Heron’s two books, About Pneumatica, introduced observations of nature. But unlike pure science that steam as a major driving force. He did not invent involves theoretical understanding of the environment Watt's steam , but he presented basic notions but often lacks immediate implementation, his such as the lifting and driving force of steam as well as observations were applied science brought to use. its properties under compression and expansion. Heron himself, however, explained that some of these These two books are the oldest preserved in their devices were not meant to cover any practical use but original Greek manuscripts that describe applications they were created only for aesthetic pleasure. Heron’s of pneumatic and hydraulic control systems; they devices were explored and reproduced by Romans, comprise a systematic collection of machines dating Arabs and Byzantines and served as the link that before and during his lifetime. These machines moved united the Ancient Greek and the European with water, air or steam pressure, produced sounds technologies of the Renaissance that marks the and were intended to decorate public places and to beginning of the technological advances of Western amaze or serve the practical needs of the spectators. Civilization. Figures 11 and 12 illustrate the oil press Although in his books he describes a menagerie of and a hoisting machine, two of Heron’s creations. mechanical devices, or ‘toys’ like singing birds, Figure 13a shows the agiasterion that which supplied puppets, coin operated machines, a fire engine, and a an amount of holy water by throwing a coin, Figure 13b water organ, his most famous invention is the first the water mechanism for the automatic opening of the steam powered engine, of special significance to the gate of a temple, Figure 13c the dioptra, mechanism science of automation because he presented useful in geodesics, and Figure 13d the armonio, automatic means necessary to control steam supply. musical instrument operated by air pressure. Figure 14 The device consists of a sphere mounted on a boiler depicts Heron’s steam boiler and Figure 15 the and supported by an axial shaft with two canted , along with modern reproductions. nozzles that produce a rotary motion as steam Mechanical achievements during those centuries escapes (Greek word /*µ1"*589)$1:); it constitutes a were very significant. The world had one of the revolutionary entry into the field of today’s automatic greatest geniuses, Archimedes, who devised control. remarkable weapons to protect his native Syracuse Among Heron’s inventions are the ‘automatic from the Roman invasion and applied his powerful theaters’, capable of conducting an entire theatrical mind to such basic mechanical devices as the screw, performance with automatic portals, changing the , and the . Alexandrian engineers, such automatically the stage props, and moving puppets as Ktesibius and Heron, invented a wealth of ingenious that performed a myth. For these mechanical mechanical contrivances including pumps, wind and automata, Heron wrote "A prop is placed on a pylon hydraulic organs, compressed air engines, and screw depicting a theatrical scene with portals that open and cutting machines. They also devised toys and close automatically. Therefore, it allows several scenes automata that may be regarded as the first successful of a play to be enacted in sequence and the puppets steam turbine. are able to move, act, and speak or produce sounds Little practical use was found for these inventions, like live characters. In addition, fires are lit but the Alexandrian school marks an important automatically and new puppets appear on the stage transition from very simple mechanisms to the more until the end of the story". complex devices that properly deserve to be

266 TuA07.4

considered machines. In a sense, the School of mathematics spread through the Arab world and from Alexandria provided a starting point for modern about the middle of the 9th century, the Arabs produced mechanical practice. scholars like the astronomer and geometer Thabit ben Qurra and the polymath Al Kindi [18], [26]. IV. GRECO-ROMAN PERIOD & TRANSITION TO BYZANTIUM The Roman Empire became the dominant force in V. DISCUSSION AND CONCLUDING REMARKS the greater Mediterranean region starting at 100 B.C. The central objective of this study was to provide The Romans were responsible, through the application justifications and evidence related to technology and and development of available machines, for an autonomous mechanisms in the Mediterranean region important technological transformation: the widespread and the ancient Greek world. Indeed, it has been introduction of rotary motion. This was exemplified in shown that the Mediterranean region was the hub from the use of the treadmill for powering cranes and other where the foundations of modern western science and heavy lifting operations, the introduction of rotary water technology were laid. raising devices for irrigation works (a scoop The foundations were very strong based not only on powered by a treadmill), and the development of the ingenious solutions to specific problems but also waterwheel as a prime mover. Vitruvius, a Roman drawing from first principles that govern natural engineer gave an account of , and by the phenomena and from powerful mathematical concepts end of the Roman era many were in operation. also developed in the same geographical area during The Roman Empire was split in two parts around the same time frame. 350 A.D. with Rome being the capital of the Western It should not be overlooked that this paper touched part and Byzantium, later called Constantinople only upon mechanisms as mostly related to the (today’s Istanbul), the capital of the Eastern Roman discipline of (feedback) control, without even making Empire. The eastern Roman Empire also called an attempt to state accomplishments is other areas. Byzantine Empire became distinctly Greek as opposed However, there is documented evidence and proof of to its western Roman counterpart. The level of major inventions in areas like Architecture, Metallurgy, knowledge declined much more rapidly in the Roman Marine Engineering and ship building, and west than in the Greek east. Inventions in Byzantium hydraulic projects, construction engineering, music derive from Heron’s era as shown in Figure 19 that instruments, everyday life, mechanisms using series of depicts mechanical animals and birds of the Byzantine bolts and spur gears, to name a few [2], [27]. throne. Therefore, as it has been demonstrated, ancient In the West, what survived was mostly contained in Greek technology was rather complex but also very handbooks as collections of known facts. Notable dominant and did not lack contributions to society. It is examples are Pliny’s Natural History (75 A.D.), Aulus very misleading to claim that Greeks contributed only nd Gellius Attic Nights (2 centuryrd A.D.), Slinus’ to philosophy, arts and sciences excluding technology. Collection of Remarkable Facts (3 or 4th century Perhaps this erroneous statement was partially A.D.). because of Plato, his fight against Archytas the In the East, by contrast, much more of the Greek Tarantine as well as his passion for science and not science was preserved. The tradition of scholarship technology with the meaning of learning how to do or kept knowledge alive from the ancient scientific texts fix something [27]. (through scholarly discussions and the publication of It is also true that most of such inventions originated commentaries in addition to original texts) even when in areas away from , but it is the Athenian the scholarly commentators themselves did not attempt Philosophers who eventually recognized and to engage in original scientific research on their own supported the need for technology in parallel and in account. Much of what is known today about Greek addition to philosophy, arts and sciences. More details science is due to this tradition. may be found in [28]. By the year 600 A.D. preliminary efforts had already As evidence and references continue to mount in been made to turn part of the Greek corpus of scientific quantity, it will not be before long that there is a learning into Latin in the West and into Syrian in the complete picture of what was accomplished and East. Greek science was converted first into the invented during that time. Regardless, those were Arabic tongue in the 9th and 10th centuries and then exciting times indeed! once again from Arabic and Greek into Latin in the 12th and 13th centuries. Although the Greek corpus Acknowledgements: We acknowledge the sources received major additions and modifications at the of the schematics and pictures used in this article. hands of Arab and Latin authors, it was still essentially They include [2], [5], [14], [23], [24], [27]. the Greek learning that made its way to the Latin west. After the fall of Alexandria to the Arabs (642 A.D.), knowledge of medicine, biology, astronomy and

267 TuA07.4

REFERENCES 18. G.E.R Lloyd, Greek Science after Aristotle, W.W. Norton, New York, 1973. 1. P. Antsaklis, G. Vachtsevanos, M. Polycarpou 19. Vitruvius, The Ten Books on Architecture, Morris (Organizers), “Is Feedback Control a Hicky Morgan translation, Dover, New York, 1960. Mediterranean Invention?” Panel discussion on the 20. P. Valavanis, Hysplex, The Starting Mechanism in Early History of Autonomous Mechanisms, 13th Ancient Greek Stadia. A Contribution to Ancient Mediterranean Conference on Control and Greek Technology, PhD Thesis, California Automation and IEEE International Symposium on University Press. Intelligent Control, Limassol, , June 27-29, 21. D. Guedj, Le Theoreme du Perroquet, Editions du 2005. Seuil, 1998. 2. C. Lazos, Engineering & Technology in Ancient 22. R. MacLeod Ed., The Library of Alexandria: Centre Greece, Aeolos Publications, 11th Edition, Athens of Learning in the Ancient World, I. B. Tauris, 1993. London, 2004. 3. J. Reichardt, : Fact, Fiction and Prediction, 23. C. Lazos, The Adventure of Technology in Ancient Thames and Hudson Ltd., 1978. Greece, Aeolos Publications, 2nd Edition, Athens 4. M. Hillier, Automata and Mechanical Toys, 1999. Bloomsbury Books, London, 1976. 24. C. Lazos, Archimedes, The Intelligent Engineer, 5. O. Mayr, The Origins of Feedback Control, MIT Aeolos Publications, 4th Edition, Athens 1995. Press, 1970. 25. Heron of Alexandria, Automatopoietica, D. 6. O. Mayr, “The origins of feedback control,” Kalligeropoulos translation into modern Greek, Scientific American, vol. 223, no. 4, pp. 110-118, commentary and original figures (in Greek), Foiniki, 1970. Athens, 1996. 7. O. Mayr, Feedback Mechanisms in the Historical 26. A. Cameron, The Mediterranean World in Late Collections of the National Museum of History and Antiquity AD 395-600, Routledge, London, 1993. Technology, Smithsonian Institution Press, 27. , Published on the Washington DC, 1971. occasion of the World Exhibition, EXPO 2000, by 8. S. Bennett, A History of Control Engineering, 1800- the Technological Museum of Thessalonica and 1930, IEE Press, Peter Peregrinus Ltd, London, GSRT, 2000. 1979. 28. D. Kalligeropoulos, Myth and History of Ancient 9. S. Bennett, A History of Control Engineering 1930- Greek Technology and of Automata – Vol. A, 1955, IEE Press, Peter Peregrinus Ltd, London, Technology in Ancient Greek Myth (in Greek), 1993. Kastaniotis Publications, 1999. 10. S. Bennett, “A Brief History of Automatic Control,” IEEE Control Systems Magazine, vol. 16, no. 3, pp. 17-25, 1996. 11. H. S. Black, “Inventing the negative feedback amplifier,” IEEE Spectrum, vol. 14, no. 12: pp. 55- 61, 1977. 12. H. W. Bode, “Feedback – the history of an idea,” Reprinted in Selected Papers on Mathematical Trends in Control Theory, eds. R. Bellman and R. Figure 1. The hysplex, invented in the 5th century B.C. Kalaba, Dover, 1960.

13. D. Bernstein and L. Bushnell, Eds., “History of

control”, Special Section, IEEE Control Systems Magazine, vol. 22, no. 2, April 2002. 14. Ancient Greek Technology, Proceedings, 1st International Conference, Thessalonica, Greece, 1997. 15. N. Karcanias, S. Vasileiadou, and D. Kalligeropoulos, “The Origin of Systems Concepts in Ancient Greece,” Proceedings 2nd International Conference on Ancient Greek Technology, Athens, Greece, October 2005, pp. 17-21. 16. C. Marshall, Greek Science in Antiquity, Collier Figure 2. Catapults used by Philip and Alexander the Books-MacMillan, New York, 1963. Great. 17. G.E.R. Lloyd, Early Greek Science: Thales to Aristotle, W.W. Norton, New York, 1970.

268 TuA07.4

Figure 3. Types of battlefield catapults taken from [27].

Figure 7. Drawing of the water clock of Archimedes.

The façade (A), the cross section (B) and the back view (C).

Figure 4. Modern reproductions of different catapults and crossbows taken from [27]. Figure 8. The water musical instrument of Ktesibius, and rare terracotta model.

Figure 5. The steam gun invented by Archimedes and its reproduction.

Figure 6. Representation of the endless screw and its modern reconstruction in Liverpool in 1930.

269 TuA07.4

Figure 9. The water clock of Ktesibius and modern reproduction.

Figure 10. The force of Ktesibius and modern reproduction. Figure 13. Four inventions by Heron.

Figure 14. Representations of the steam boiler from Heron’s writings and physical reconstruction of the device. Figure 11. Representation of the oil press and modern reproduction.

Figure 15. Heron’s odometer and reconstructions of the Figure 12. The monokolos hoisting machine. odometer by Woodcraft.

270