56 



tfh March, 1890. 



John H. Greenhill, Esq., in the Chair. 



Professor Fitzgerald, C.E., read a Paper on 



THE THEORY OF THE SCREW PROPELLER, 



Which is printed as Appendix II. to this Report. 



The Chairman having put a number of questions to Professor 

 Fitzgerald arising out of the paper, called upon 



Mr. John H. MacIlwaine, who said that, in his opinion, the 

 Professor has launched a completely novel theory on the subject 

 of the Screw Propeller, namely, that the vortexes in which the 

 screws work should have screws made to suit them. He 

 considered that there is much difficulty as to the question of 

 pitch being ascertained mathematically, and gave three reasons 

 why he believed Professor Fitzgerald's theory is not practicable. 



Mr. J. Maxton did not consider that the theory put forward 

 would be of any practical result, as, in his opinion, the 

 Professor's ideas are not in accordance with those which would 

 result in the construction of a perfect Propeller. 



Mr. Walter H. Wilson gave some interesting results 

 regarding the lapping of twin Propellers, as observed in a 

 model made with screws fifteen inches in diameter. The after 

 Propeller was found to go slightly faster than the other, say two 

 revolutions in the minute. This was found to be the case with 

 regard to the steamer Teutonic. 



Professor Everett having offered a few remarks as to twin 



screws 



Professor Fitzgerald replied. 



