Newton, who was the first to study the resistance that fluids offer to a body moving in them, stated implicitly that the molecules of the fluid remained immovable up to the moment that the body touched them, and returned to a state of rest immediately afterwards.

He found that the resistance experienced by a flat surface was proportionate, 1° to its extent, 2° to the density of the fluid, 3° to the square of the velocity, 4° to the square of the sine of the angle of incidence, and 5° that it is normal to the surface. It was, however, soon discovered that this theory, altogether empirical, was often at discord with what experience taught, and a great number of experimental researches have been made at different periods in order to throw further light on the subject.