The Forces on a Circular Cylinder 534 
that is by the first term in (29) or (30). The unit of force in each case is 
mgoea?, that is the weight of liquid displaced by the cylinder per unit length. 
It should be noted also that, in addition to the vertical force Y, there is the 
usual hydrostatic buoyancy. The curves for the wave resistance show 
clearly the increased values at lower velocities and also the displacement 
of the position of maximum resistance, the latter occurring at a lower 
speed than the value ,/(gf) given by the first approximation. 
0:5 
Fic. 1. 
SUMMARY 
A solution is given for the two-dimensional wave motion due to a 
circular cylinder in a uniform stream, taking fully into account the con- 
dition at the surface of the cylinder. Expressions for the horizontal and 
vertical forces on the cylinder are obtained in the form of infinite series 
in ascending powers of a certain parameter. Numerical calculations are 
made from these and compared with the known first approximations. 
The main effect of the additional terms upon the wave resistance is to 
increase the calculated value at low velocities and to decrease it slightly 
at high velocities. 
Reprinted from ‘ Proceedings of the Royal Society of London’ 
Series A No. 892 vol. 157 pp. 526-534 December 1936 
HarRISON AND Sons, Ltd., Printers, St. Martin’s Lane, London, W,C.2 
