Studies in Wave Resistance. 583 
we use as a pase the quantity V/,/L, where V is the speed in knots and 
L is the length in feet ; thus we have, in the previous notation, 
— gl 
ee L - 
Sa 11:594 ye Prox. (40) 
The range for V/,/L, which is of special interest, is from about 0°75 
to 1:25. Fig. 2 shows the curves of wave resistance for the four models, 
obtained by calculating R from the expressions (31) to (39). 
Comparison with Ship Resistance and General Conclusions. 
11. In studying these curves in relation to experimental data from ship 
models, one cannot make a direct numerical comparison of absolute values. 
In the present calculations one has the advantage of isolating some single 
feature and of seeing how its variation affects the results, for instance, the 
form of the level lines. On the other hand, in experimental curves from 
models there is no simple separation. In practice, the form of the ship 
is expressed roughly by certain coefficients of fineness: the water-plane 
coefficient being the ratio of the area of the water-plane section to a 
rectangle enclosing the section, the mid-ship area coefficient similarly 
defined, the prismatic coefficient, the curve of sectional areas, and so forth. 
In experiments these coefficients may be varied in a systematic manner, but 
in their effect on the ship’s form they are not in any mathematical sense 
independent variables ; this leads to some difficulty of interpretation from a 
theoretical point of view, 
211 
