Surface friction: Experiments with steam and water in pipes

During the past hundred years much work, both theoretical and experimental, has been carried out with a view to determining tbs character of the laws governing tbs resistance to tangential motion between solid surfaces and liquids or gases. A general relation between the dimensions of the surface, the velocity, the density of the fluid, and its viscosity bad been surmised as a consequence of the laws of motion by Stokes, Helmholtz, and Osborne Reynolds, but it was left to Lord Rayleigh to show, from the principle of dynamical similarity, that the phenomena involved could be expressed definitely by a simple mathematical formula. The laws governing tbs friction between solid surfaces and water have formed the subject of experimental investigations by Froude, Osborne Reynolds, Darcy, etc., whilst the parallel case of the resistance to motion between solid surfaces and perfect gases has occupied the attention of Zahm, Brix, Stockalper, and others. Practically all these investigators devoted their energies to experimental determinations of the friction in the medium which they employed, and it was not until the subject was taken up by Stanton and Pannell that any attempt was made to investigate the similarity, under certain conditions, of the motion of fluids which differed widely amongst themselves in their properties of densities and viscosities. The same investigators also took up the question of the limits of accuracy of the formulæ currently accepted at the time and used in calculations of surface friction.