168 VARIATIONS OF SHAFT HORSE-POWER, ETC., 



tem adopted in measuring the hull efficiency elements, because it is entirely different to that 

 employed in Great Britain. 



I had an interesting correspondence with Mr. R. E. Froude of the British Admiralty 

 Experiment Works on the subject, and he thought that the difference between the two sys- 

 tems could be summed up as follows : — In Great Britain the character of the investigation 

 was such as to obtain definite measurements of discrete parts, whereas in America the system 

 was directed towards measurements of concrete wholes. That is, perhaps, criticism of a some- 

 what theoretical nature and, for my part, I was particularly impressed with the American sys- 

 tem of measuring the hull efficiency elements. I should like to see, and hope I shall see, when 1 

 return to England, experiments made on these lines and the results compared with those made 

 according to the practice in our country. 



I may say that Commander McEntee's deduction as to the advantages and disadvan- 

 tages of the full and fine stern agrees with some of the actual results we have had with ships 

 differing in fullness of stern, but otherwise similar, designed and built in Great Britain during 



the war. 



With regard to Professor Sadler's paper experiments were carried out in Great Britain 

 on simplified forms, and a form was developed by the Director of Naval Construction at the 

 Admiralty that gave results similar to those stated by Professor Sadler, viz., that a simpli- 

 fied form can be designed with practically no increase in resistance over a form of the ordi- 

 nary type. These results were communicated to the United States Navy Department and 

 the Shipping Board, and experiments were made at Washington, which, I understand cor- 

 roborated the results obtained in England. 



I do not believe the re&tilts of the British experiments have been published, and it may 

 be of value to have them forwarded for insertion in the transactions of this Society. I 

 should have great pleasure, if you wish, in writing to Sir Eustace D'Eyncourt and asking 

 him if he will agree to the insertion of these results in the transactions of this Society. 



The President: — We shall be very glad to have these figures. Is there any other 

 gentleman who wishes to discuss these papers or either one of them? 



Mr. Alfred J. C. Robertson, Member: — Mr. President and gentlemen, it is very en- 

 couraging to discover that, in the rush of war work with which we have been overwhelmed 

 in the last eighteen months, some gentlemen have been able to give their careful thought to 

 the design of ships to meet after-the-war problems. The two papers presented to us by Pro- 

 fessor Sadler and Commander McEntee represent an enormous amount of work. 



In connection with Professor Sadler's paper on the simplified ship forms, I might say 

 that it represents the making of probably thirteen models, and then modifying the thirteen 

 models to perhaps get twenty models in all. These twenty models have been tested in each 

 case at three different drafts and probably twenty or thirty runs were given for each model, 

 so that you see the amount of work is very great and the paper does not bring that out 

 without careful study. 



I had the pleasure of looking into some of the figures given here, and the results, in my 

 opinion, are quite worth calling your attention to. Two types of models were tested; the 

 first type was for a fine model and had three parallel middle bodies. Results are given with- 

 out parallel middle body, and with 10 per cent and 20 per cent of parallel middle body in- 

 serted. In the results the box form shows an average of 2.4 per cent more resistance than the 

 straight frame model with the corner cut off diagonally. 



