IV.—On the Equilibrium of Elastic Solids

There are few parts of mechanics in which theory has differed more from experiment than in the theory of elastic solids. Mathematicians, setting out from very plausible assumptions with respect to the constitution of bodies, and the laws of molecular action, came to conclusions which were shewn to be erroneous by the observations of experimental philosophers. The experiments of Œersted proved to be at variance with the mathematical theories of Navier, Poisson, and Lame and Clapeyron, and apparently deprived this practically important branch of mechanics of all assistance from mathematics.