From Ancient Greece to Byzantium

Proceedings of the European Control Conference 2007 TuA07.4 Kos, Greece, July 2-5, 2007 Technology and Autonomous Mechanisms in the Mediterranean: From Ancient Greece to Byzantium K. P. Valavanis, G. J. Vachtsevanos, P. J. Antsaklis Abstract – The paper aims at presenting each period are then provided followed by technology and automation advances in the accomplishments in automatic control and the ancient Greek 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 force 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 Miletus (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 engineering, 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 machines, 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]. mechanism 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 Ctesibius) of Alexandria (circa 270 B.C.) as runners. The ends of the ropes were tied at the peaks reported by Vitruvius (circa 25 A.D.), Heron (or Hero) of vertical wooden posts implanted in mechanisms of Alexandria (circa 60 A.D.) and Philon 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 clock 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 Plato, Aristotle, the Epicureans and Stoic philosophers. major contributors. Details of achievements during iii) The Hellenistic (in Greek '$$%()"*)+,) period, 300- 100 B.C. with main representatives Euclid, K. P. Valavanis is with the University of South Florida Archimedes, 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 Alexander the Great, 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 (Hippocrates 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 angle 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 Mathematics 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 tool; 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, Pythagoras, Euclid, Focusing on mechanisms, technological innovation Archimedes, and Apollonius were mathematicians 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 mathematician 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 Archytas from the city of Tarantas technology: Plato’s Academy, Aristotle’s Lyceum, and (in south Italy), known as Archytas the Tarantine (also The Library of Alexandria. 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 Egypt [16] - [18], created the first Unmanned Aerial Vehicle 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 machine flew about 200 Miletian School and particularly Thales of Miletus. 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 tyrant 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].

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