Hydraulics: The Importance of Observations and Experiments

Abstract

Before the expansion of analysis, studies of fluid mechanics were necessarily confined to experiments although a complete body of technical applications of hydraulics had developed starting with the most ancient civilizations around the Mediterranean Sea and in Asia. Greeks, Egyptians and Romans, in particular, conceived all kinds of elementary machines but also well designed systems of distribution of water, whether in the fields or in the supply of cities. The true experimental aspects concerning this matter had to await the birth of the modern scientific spirit of the Renaissance period. The notion of pressure, the most elementary form of stress, appears with experiments performed by Torricelli, Pascal, and Mariotte. With these scientists and Newton, the first formulas appear, some just reporting pure empirical results, others founded on some rational reasoning. In the eighteenth century one witnesses parallel developments in the works of mathematicians (mostly, Clairaut, the Bernoullis, d’Alembert, Euler and Lagrange) and in the careful experiments of a group of gifted engineers (e.g., Borda, Bossut, du Buat,..). The role played by viscosity, but still in laminar flows, will be best captured by Poiseuille, Hagen, and others in experiments, and obviously by Navier, Saint-Venant and Stokes in analysis, before the consideration of turbulence. Accordingly, this contribution places the emphasis on experiments that were decisive in the perused evolution of continuum mechanics, from ancient times to the nineteenth century.