12 EXPERIMENTS ON THE FULTON AND THE FROUDE. 



It is therefore proposed that tow-boats shall be powered for towing at 

 a speed -length ratio of 0.6 to 0.7 by the equation 



i.H.p.=5|E!, 



where D is the displacement in tons (2,240 pounds), V is the speed in knots 

 per hour, and L is the length on water-line in feet, while K is the admiralty 

 coefficient. The speed-length ratio is computed by the formula — 



V 



Vl 



The speed-length ratio of the Froude when towing at 3! knots was 0.6 

 and the admiralty coefficient corresponding is 2 1 . The Fulton when towing 

 at 35 knots had a speed-length ratio of 0.67, and for it the admiralty coeffi- 

 cient is 22.5. 



Having determined the power for towing at a given speed, the speed 

 running free may be investigated or we may simply accept what we get; 

 especially at or near the critical speed it takes a large increase in power to 

 affect the speed appreciably. 



*To complete the design requires the determination of the proper size 

 and proportions of the propeller. Through the courtesy of the Chief Con- 

 structor, Admiral R. M. Watt, U. S. N., tests of models of our propellers for 

 the Fulton have been made with large slips required for towing, by Naval 

 Constructor Taylor. From these tests and from our own data on thrust I 

 hope to be able to present an analysis of this matter at some future time. 



DISCUSSION. 



Mr. John Reid, Member: — I think the principal charm of this paper is in the 

 practical applications which Professor Peabody has scattered all through it, and 

 the only reason that I am before you is that I think his conclusions are sometimes 

 erroneous. I would like particularly to call attention to one extraordinary state- 

 ment which he has made, and that is that from his experience with these experiments, 

 the internal-combustion engine, with its high revolutions, can be fitted into a tug, 

 and that the consequent high revolutions of the propeller would have very Httle 

 efifect upon the efficiency of the boat as a tug. I have had a little experience with 

 that in the last twelve months, and I can inform Professor Peabody, so far as my 



