158 WAVES OF SAND AND SNOW 



to the eddy-curve I mean therefore only one-half 

 of the curve which encloses the area where the 

 surface of the water shows eddying disturbance. 

 If we suppose the eddy-curve to be rotated about 

 its longer axis, it would trace out a cigar-shape4 

 form, which is that which, after much experiment, 

 was adopted for torpedoes. At first these were 

 driven with their sharp end foremost, although 



Fig.; 16 



Plan of snow drifi caused by clump of bushes , wind from the left; 



every seaman knew that a spar is best towed blunt 

 end foremost. They steered badly, and the form 

 was gradually changed until the head was blunter 

 than the tail. Professor Hele Shaw has proved 

 by experiment that cigar or torpedo-shaped bodies 

 have greater resistance if towed with their sharp 

 end first, and has shown that this is due to the 

 drag of the eddying wake formed behind the blunt 



