APPENDIX II. 



NOTE TO 



PAPER ON THE THEORY OF THE SCREW PRO- 

 PELLER, READ BEFORE THE BELFAST 

 NATURAL HISTORY AND PHILOSOPHICAL 

 SOCIETY, ON MARCH 4, 1890, BY M. F. 

 FITZGERALD, M.I.M.E. 



jJHE water is throughout considered as flowing past the 

 propeller, whose only motion is one of rotation about 

 its axis. The principal symbols employed are as follows : 



j£=velocity of water past the propeller, taken to be, at a 

 distance from it, in lines parallel to its axis ; in other 

 words K is the speed of the ship through the ocean. 



#=*velocity of water at the propeller, resolved parallel to 

 its axis. 



#=distance measured along as parallel to axis of any point 

 from a fixed plane at right angles to axis, say for instance 

 from the plane of the after end of the stern tube. 



r=radial distance of any point from the axis of the screw. 



I2=angular velocity of the screw ; so that at radius r the 

 circumferential velocity of the screw is r&. 



o)=angular velocity of the water ; so that at radius r the 

 circumferential velocity of the water is rw. 



i?=radius of screw disc, i.e. radius to tip of blades. 



