On the effect of the form of the transverse section on the frictional resistance to the motion of an elongated body parallel to its length through a fluid

1. The great increase in tire lengths of the parallel mid-bodies of recently constructed submarines and airships has raised into prominence the question of the frictional resistance of such elongated bodies moving parallel to their length through fluids, like air and water, whose viscosities cannot be neglected. This resistance increases as the length increases, and benefits comparable with the head and tail resistances, which for short bodies constitute nearly the whole resistance. In general, the problem of greatest practical importance is the determination of the frictional resistance when the motion is rapid enough to produce eddy currents in the fluid, but the difficulties in the way of a general theory of eddy current motion have presented a solution being reached. The simpler problem of the resistance offered by the walls of a circular pipe to the turbulent flow of viscous fluid through the pipe formed the subject of extensive series of experiments by Saph and Schoder, of Cornell University, and by Stanton and Pannell at the National Physical Laboratory.