EXPERIMENTS ON THE FROUDE. 117 
We have found in our own experiments that what we have done with the 
smaller launches has been of the greatest value in predicting, not only the speed, 
but the behavior of the larger size vessels. Launches from 20 feet to 40 feet long 
have given us most valuable information, and in banking on what we found from 
them we have not gone wrong. 
I believe there is a possibility of small errors creeping into any such investiga- 
tion. I do not believe a model ship by even the best shipyard will be an exact 
representation of the large sized ship. She will be near enough for practical pur- 
poses, but there may be differences which would tend to account for the fifteen per 
cent. 
Moreover, the surface of a model which is kept in the water for testing, very 
soon loses a definite factor. We find in our racing boats that after a week to ten 
days, it is absolutely necessary to take the boat and put her in fresh condition, 
otherwise she is badly beaten. 
I am only giving these thoughts as an addition to Mr. Peabody’s paper, which 
seems to me to be of very great value to the members of this society, and to every 
student of naval architecture, and I regret with Professor Peabody that Dr. Weld 
is no longer living, and I hope that this may not be the stoppage of these valuable 
experiments. 
Mr. WiLL1aM T. DONNELLY, Member:—I do not know that I can add anything 
particular to the discussion, but I would like to ask Professor Peabody if he can give 
us some information as to what, in his judgment, was the nature of the improvement 
due to the moving of the propeller farther from the stern-post. Was the increased 
efficiency due entirely to eliminating the action of the stern-post or was it partially 
due to the moving of the propeller from the after-body of the ship, thus reducing 
the influence of the propeller from the hull resistance. 
It would seem that the reason propellers are kept so close against the stern-post 
is the matter of mechanical construction; that is, to obtain rigidity. The impor- 
tant point to be considered is the amount of saving that will be brought about by 
elaborating the design so as to carry the propeller further away from the stern-post, 
and what may be of equal or more importance, further away from the after-body of 
the vessel, where the propeller will have less tendency to reduce the water pressure 
on the after lines. 
I should be pleased if Professor Peabody could throw any additional light on 
these points. 
VICE-PRESIDENT McFarLANp :—Is there any one else who desires to speak on 
the subject? If not, we will ask Professor Peabody to make his reply. 
PROFESSOR PEABODY :—I want to thank Professor Sadler for the criticism and 
appreciation he has given of this paper. I also want an opportunity to thank him 
