STABILITY, PROPULSION, AND SEA-GOING QUALITIES OF SHIPS. 43 



Mr. Fronde's Exj^Ianations. 



The subject of a ship's resistance is one -which I have for many years been 

 independently investigating, both theoretically and experimentally; and I 

 have been thus led to conclusions which are in very material respects at 

 variance with those -which Mr. Merrifield has placed on record for the Com- 

 mittee as representing the existing state of knowledge respecting it, and 

 specially at variance with the consequent recommendations which he has 

 drawn up, as indicating the experiments for the performance of which the 

 assistance of Her Majesty's Government is to be sought : I thus find myself 

 somewhat abruptly placed in a position in which I must ask permission to 

 present, as part of our proceedings, a supplementary report explaining the 

 reasons which oblige me to dissent from the recommendations to which I 

 refer. Until the Draft Eeport was in my hands, I was unaware that '•' Ke- 

 sistance" was regarded as included in the list of subjects submitted to the 

 Committee; for I understood the terms "Stability" and "Sea-going quali- 

 ties" as having reference to the theory of " EoUing motion," and " Propul- 

 sion" to the theory of the Action of Propellers. The subject of Resistance 

 appeared to belong already to the " Steamship Performance Committee." 



Let me say at the outset that Mr. Merrifield's very full discussion of this 

 subject appears to me to set forth most lucidly what must be called " the 

 existing state of knowledge" respecting it; it has evidently involved much 

 laborious research and deep consideration. 



And, on the other hand, the results at which I have arrived are in many 

 respects so far from complete that I have hitherto hesitated to bring them 

 before the public. But I believe I have so fully established those conclusions, 

 to which I shall now refer, and the difference in the Hne of action to which 

 they point is so serious that, under the present circumstances, I feel bound 

 to press them on the notice of the Committee. 



The Eeport specially recommends, as the experiment which it is important 

 to try, the dynamometric determination of the scale of resistances for a 

 full-sized ship. 



Now, -without impugning, or rather, while fully asserting that any scale of 

 resistance, in terms of velocity, accurately determined for a full-sized ship, 

 would be of real value and of great interest, I shall nevertheless contend (1) 

 that experiments on the resistances of models of rational size, when ration- 

 ally dealt -with, by no means deserve the mistrust -with wliich they are usually 

 regarded, but, on the contrarj', can be relied on as truly representing the 

 resistances of the ships of which they are the models ; and (2) that in order 

 properly to open up the question, so great a variety of forms ought to be 

 tried that it would be impossible, alike on the score of time and expenditure, 

 to perform the experiments with fuU-sized ships. Both these propositions 

 require to be drawn out at some length. The kindred proposition, that as 

 accurate results can be obtained far more easily and rapidly in experimenting 

 with a model than -with a ship, though of great importance, is so obviously 

 true as to require no elucidation. 



The natural expectation that the ascertained resistance of a model will 

 furnish a measure of the resistance of a ship similar to the model, depends 

 on the prima facie probability that the resistance for a given body wiU vary 

 as the square of its velocity ; and that in comparing similar bodies of different 

 dimension at a given velocity, the resistance will be as the square of the 

 dimension, since that function expresses alike the proportion of the respec- 

 tive midship sections and of the respective £riction-.bearing surfapes. Were 



