60 THE EXPANSION OR CONTRACTION OF DIMENSIONS, ETC. 



as the beam, or the residuary resistance per ton of displacement was constant at 

 corresponding speeds. 



In conclusion, a word of caution should be given about extending the above 

 results beyond the limits of the experiments, both with regard to dimensions and 

 speed. Within these limits of, say, 20 per cent variation no serious error will be 

 involved if the residuary resistance per ton of displacement at constant speed- 

 length ratios be assumed to vary as about the .7 power of the breadth, inversely as 

 the .3 power of the draught, and inversely as the .4 power of the length; or the 

 residuary resistance be assumed to vary as the 1.7 power of the breadth and as the 

 .7 power of the draught, and .6 power of the length, for similar normal mercantile 

 types at corresponding speeds. 



The results also emphasize the fact that the draught is the more economical 

 dimension to increase, if increased displacement of a given type is desired. 



For very wide and shallow forms, however, the influence of breadth upon resid- 

 uary resistance does not appear to be as marked as in the case of the more normal 

 forms. 



The Chairman : — ^In the unavoidable absence of the author, which, I am sure, we all 

 greatly regret. Professor Sadler will read paper No. 7, "Some Experiments with Models 

 Having Radical Variations of After Sections," by Naval Constructor D. W. Taylor, U. S. N. 



Professor Sadler presented the paper. 



