THEORETICAL HYDRAULICS, AUTOMATA,
AND WATER CLOCKS
Theoretical and practical mechanics and hydraulics first blossomed under the stimulus of a new mechanistic philosophy in the third century B.C. As part of this process, automata and water clocks, though they had an earlier ancestry, blossomed too. They go hand in hand: they often employed the same principles, and automata often served as the jackwork or side-shows attached to clocks. They are of prime technical importance, for they laid the foundations of the understanding of the behavior of water, of control systems, and of fine technology in general. This chapter therefore examines the background and progress of hydraulic theory, then the application of water in automata, and finally the methods of regulating the flow of water in clocks.
The term hydraulics is, in its modern sense, a modern coinage for which the Greeks had no counterpart. They were not particularly concerned with the behavior of water as such, whereas they were considerably interested in what they called pneumatics. Literally, this means the behavior of air, although a more accurate description of its content might be the study of pressure, from which some hydraulic theory did derive. The reason for this lack of interest in water was perhaps that it is visible and tangible and, in the natural world, behaves (apart from phenomena like tides) in a fairly obvious way: for example, the cycle of evaporation from the sea, rainfall, and rivers flowing downhill was well understood. Air, however, being invisible, was more mysterious and its properties were seemingly in greater need of explanation.
Science grew out of philosophy; but early ideas about the nature of water by speculative philosophers such as Thales in the sixth century B.C. (who felt that water was the original constituent of all matter)