202 Dr. T. H. Havelock. [June 7, 
the bow and stern systems, y is larger at the higher displacements, while x 
is less; both variations are consistent with a diminution of the distance 
between the axes of the simple equivalent pressure distributions. 
To illustrate the smaller changes which are possible at the same displace- 
ment, three models are taken from the same paper, having different midship- 
section coefficients with the same area of midship-section; thus smaller 
coefficients are associated with greater beam and draft. One of these three 
is No. 1 of Table 1: midship-section coefficient = 0:9, @=81, m= 2°7. 
Another of the set I had already used in my previous paper with the results: 
midship-section coefficient = 0°7, 8 = 82:5, m = 2°53. For the third of the 
series the same coefficient is 11, and there is a good agreement by taking 
B = 79-5, m = 2°87. 
4. The next sets of experimental results are taken from a paper by 
D. W. Taylor* on the influence of length of parallel middle body. One must 
notice that the problem investigated is not quite the same as in the paper 
by W. Froude referred to above. In the latter case the bow and stern of 
the model were unaltered, but varying lengths of parallel middle body were 
inserted between them, so that the special effect was isolated as far as 
possible. In Taylor’s experiments the models have constant length and 
displacement, but varying proportions of the length are occupied by a 
parallel middle body, and, of course, the bow and stern vary in form so as to 
keep the displacement constant ; the effect is thus more complex theoretically. 
We may anticipate the direction of variation of some of the coefficients 
with increasing percentage of parallel middle body under these conditions. 
Since the ratio of the length of entrance and run to the length of the ship 
becomes less, the index m should decrease ; also the effective distance apart 
of the bow and stern systems becomes greater, so at the same time y should 
decrease and 7 increase. 
Table II.—Models V to VIII. 
Percentage of | Cylindrical 
No. parallel coefficient a. B. Y- m. n. 
middle body. of ends. 
Vv 10) 0-740 2°5 135 0°17 2°53 584, 
VI 24 0 658 2°0 145 0°16 2°45 584 
VII 36 0-594 2°0 155 0°14 2°35 605 
VIII 48 0 ‘500 2°0 165 0:12 2°10 650 
Displacement = 1000 lbs. ; length = 20°51 feet; beam = 1°682; draft = 0°673; displacement- 
length coefficient = 53°2; midship-section coefficient = 0:96 ; beam/draft = 2 °5. 
*D.W. Taylor, ‘Trans. Amer. Soc. Nav. Arch.,’ vol. 17, p. 171 (1909). 
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