292 Dr. T. H. Havelock. [Apr. 1, 
V. I. I. Yates, Destroyer Model C.* 
Displacement = 575 lbs.; length = 20 feet; cyl. coeff. = 0°529. 
The experimental curve is given in Ibs. for the model on a base of V in 
knots, and is a total resistance curve, that is, it includes the frictional 
resistance. The curve is reproduced in fig. 8. 
60 
50 
Fic.8 
40 
30 
20 
R Ibs perton 
Ss | c 1.5 2 2.5 3 
This curve is not analysed here so as to compare the residuary resistance 
with the formula (20), but it is included in order to draw attention to certain 
possible complications. It may be noticed that the curve is carried to a high 
value of the speed-length ratio c, and that it continues to rise more rapidly 
after about c = 2°3 than might be expected on the present theory. Now in 
the first place it is possible that the frictional resistance may account partly 
for this rise. The ordinary estimation of the frictional resistance assumes 
that it can be calculated separately from some expression like fSV**; now 
the legitimacy of this is beyond doubt in all ordinary cases, but at high speeds 
it is possible that the form of the expression may change, or even that it 
may not be a fair simplification to divide the total resistance into simple 
additive components. 
In the second place a more important consideration must be taken into 
account, and that is the depth of the tank. For the experiments now under 
* J. I. Yates, Thesis, 1907, Mass. Inst, Tech. U.S.A. See Hovgaard, loc. cit. ante, 
50 
