92 Wave Resistance: Effect of Parallel Middle Body. 
Table V. 
2 0-625 1-27 2-02 2-73 3-45 4-14 4-83 
N 804 396 249 184 146 121 104 
Z 402 396 373 368 365 364 364 
V/JL 1-9 1-33 1-06 0-91 0-81 0-74 0-68 
In this Table the value of Z is given for the whole ship, without deducting 
the length of parallel middle body ; it is seen that in this case Z increases with 
increasing velocity over the range examined. It is difficult to determine the 
first root accurately by graphical methods, but it seems probable that Z is 
then approximately equal to the length of the ship. The increase in the 
higher values of V/,/L as compared with Table IV. is of interest. 
The particular dimensions of this case have been chosen because they are 
the same as the model for which R. E. Froude obtained the resistance curve 
and made the deductions described in §7; from inspection of the curve, 
Froude gave the following values of V/,/L for the series of humps and hollows, 
namely, 1-8, 1:28, 1-045, 0-905, 0-81, 0-73, 0-68: These may be compared 
with the last row in Table V. 
10. The comparison which has been made between the present calculations 
and experimental data has provided various points of interest. The general 
agreement is rather striking when one remembers not only the general limita- 
tions of the hydrodynamical theory, but the fact that the lines of the ship 
have been given a simple form, and further that it has been assumed to be of 
infinite draught. Except for the labour involved in the calculations, it would 
not be difficult to improve the investigation in both the latter respects. For 
instance, in former studies other forms for the ship’s lines were used in cases 
where there was no parallel middle body ; these could be used for the present 
problem, and without writing down explicit equations now it may be stated 
that the result is to vary the coefficients of the P functions in equation (33), 
and also to introduce functions of higher orders. This will no doubt affect 
to some extent the rate of change of the wave-making length ; but one cannot 
say in advance to what extent, and the point is one which must be left for 
consideration in any future extension of the calculations. 
Ha4RRISON AND Sons, Ltd., Printers in Ordinary to His Majesty, St. Martin’s Lane, 
229 
