JOINT DISCUSSION ON TWO PRECEDING PAPERS. 105 
U. S. N., in charge of the Model Basin. It was necessary to interfere with other important 
work to get in these experiments. I hope further experiments along this line, planned at the 
Model Basin, may appear in the Transactions of the Society in due time. 
TABLE I.—PROPELLERS FOR MopbE. 2441. 
1 
Models 790.7 full size. 
Propeller No................. 671 
Diameter ysis apes atin 10.8” 
Bitch syssycacies siiiocinae siclee Ups 
Tips submerged, upper position 0.7” 
Tips submerged, lower position 6.87 
Tips below keel, lower position. 2.4” 
DISCUSSION. 
THE PRESIDENT :—These two papers, No. 5, “A Study of the Wake of Certain Models 
by Means of a Current Meter,” by Prof. E. M. Bragg, Member, and No. 6, “Some Experi- 
ments on Propeller Position and Propulsive Efficiency,” by Rear Admiral David W. Taylor, 
are now open for discussion. They are two very important and very interesting papers, and 
I hope that we shall have a very interesting discussion of them. 
ProFessor L. B. CHapman, Member:—These two papers by Admiral Taylor and Prof. 
Bragg are very valuable contributions to our Transactions, and both gentlemen should re- 
ceive our thanks for the information presented today. 
Admiral Taylor in his characteristic fashion has stated his conclusions in a clear and 
concise manner, and his results will be very useful in determining the probable wake and hull 
efficiency. 
Prof. Bragg has certainly given us a great deal of information, and he has covered such a 
wide field that it has been impossible to thoroughly study his results in the short 
time available. 
When our knowledge of wake and the factors governing it has been carried a little fur- 
ther, propeller design will be much simpler and more certain than it is today. 
Taylor's data on model propellers are held to be unreliable and of little value for 
design purposes in some quarters, but this is entirely due to the fact that they have been 
used without adequate knowledge of wake values. These two papers presented today give 
valuable information for estimating the wake, and that is why I consider the papers of such 
practical importance. 
