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July 2012 www.sname.org/sname/mt (historical note )Demise of the Shock eory How the 1775-1778 French model basin experiments blew Newton?s concept out of the water BY LARRIE D. FERREIRO Isaac Newton was the rst to develop the concept of a ?solid of least resistance,? in his 1687 book, Principia Mathematica . e notion that one could shape a solid object?such as a ships? hull?to give the least possi -ble resistance was immediately attractive to shipbuilders, who set about trying to build ships with that shape. ese eorts often proved unsuccessful, as such ships sailed no faster than regular hulls. Nobody could gure out why. e explanation lay in the fact that Newton had based his solid of least resistance on the theory that resistance was due to the shock of the uid, visualizing water mol -ecules as tiny, hard pellets slamming against the bow of ship as it moved forward. For nearly a century fol -lowing the publication of Newton?s book, scientists and shipbuilders labored under this notion, but became increasingly critical of the shock theory as evi -dence mounted against it. (Today we understand that ship resistance is made up of a combination of frictional and viscous resistance.) Some of the most impor -tant experiments to undo this shock theory of fluid resistance were carried out in Paris from 1775 to 1778, though they were undertaken for a completely dier -ent purpose. e French government was considering building a new canal system that would include a nar -row, eight-mile-long tunnel, but decision makers were concerned that such restricted waterways would slow down trac. ey turned to three well-respected sci -entists?Charles Bossut, Marie-Jean Caritat (marquis de Condorcet), and Jean Le Rond D?Alembert?to exam -ine the question. By good fortune, they knew that the American scientist Benjamin Franklin had already Model basin at the Ecole Militaire, Paris 1775. Image courtesy Burndy Library, Cambridge, Massachusetts. Further Reading en To learn more about the development of ship resistance theory, check out Larrie D. Ferreiro?s book, Ships and Science: The Birth of Naval Architecture in the Scientic Revolution, 1600- 1800 (MIT Press, 2007), and his article, ?The Social History of the Bulbous Bow,? published in Technology and Culture 52/2, April 2011.