118 EXPERIMENTS ON THE FROUDE. 
now, as I could not consistently do in my acknowledgments, for giving me a very 
important piece of work in connection with the experiment I was carrying on. 
Having anticipated this difficulty about surface friction, I fondly imagined I 
could do some work on that on my own behalf. I will not go into the details of that, 
because it was a failure. Professor Sadler very kindly undertook with his model 
basin at Ann Arbor to find out what the trouble was and show me. I can thank 
him for that now, but as I had to drop out my own work in that line from presenta- 
tion, it did not seem possible to include his name in the statement which I desired 
to make. : 
In the suggestions made by Mr. Crane, there is no question that in his work on 
launches he may proceed from small launches to larger launches with the greatest 
possible advantage. That is also what has been done in the cases he referred to, 
in the model of the Mauretania, the model tested by Denny’s and the work done 
upon the Froude. ‘That is, these were all models of a full sized ship. Let us note, 
however, that they are not toys. Perhaps we believe that models 20 feet long are 
not toys. The model of the Manning had a displacement of 8 tons. She handled 
like a little steamer, and especially when she was given twin rudders to enable the 
propeller to be placed farther astern, she behaved rather badly. I speak of this, 
because I believe that is what Mr. Crane has in mind that from experiments on the 
smaller craft. you can get the greatest advantage in the design of larger craft of 
the same sort. Of course, you cannot go from launches to ships—a launch is not 
a ship on a small scale; it is a different craft. I do not think that accidental differ- 
ences in form or in displacement of models, will have any appreciable effect upon 
the experiments, when they are carried out with reasonable care. 
As for the surface of the Froude, the Charles River Basin, as was stated in the 
paper, is now fresh water, and we have taken pains to have the Froude kept painted 
and repainted, also keeping the surfaces scrubbed clean; as a matter of fact, the 
surface was clean the whole season and was not subject to fouling, and there was no 
appreciable loss of efficiency from that cause. 
As to the question asked by Mr. Donnelly, the experiments and especially the 
diagram to which he referred, show very clearly that on the Froude, and probably 
also on the Manning, the prototype, the propeller was much influenced by being set 
immediately astern of a wide stern post. 
It is also apparent from the experiments on the Froude, with and without the 
fair-water that with the propeller well astern (namely, six inches, which corresponds 
to the thirty inches on the Manning), the resistance probably was not due to the 
interference of the stern post, but was due to the general effect of the propeller upon 
the form of the stern. 
It would be very desirable, as Professor Sadler indicated, that tests should be 
made with different forms of sterns and different hulls. Although I regret the loss 
of my friend Dr. Weld I am not hopeless that we may be able to carry on the work 
in which he was so much interested. I thank you. 
a 
