ORIENTATION AND ROUTE FINDING 61 



by the perfected or best route which their experi- 

 ence has taught them. Martorelli wisely asserts 

 that orientation is not infallible, but develops 

 with age. 



Mach-Bruer attempted to localise this sense of 

 direction in the semicircular canals of the ear, which 

 are so highly developed in birds, but Dr Allen 

 contends that the theory has been refuted by ex- 

 periments on pigeons. Mobius urged that birds 

 were guided in their journey by the direction of 

 the roll of the waves ; Newton replies that though 

 this may be a constant direction in certain parts 

 of the Pacific, it is most inconstant in the stormy 

 North Atlantic (37). 



There is a very generally accepted idea that 

 birds prefer to travel with the wind striking them 

 diagonally the ' beam- wind theory/' a theory, 

 which so far as I can see, "has absolutely no sound 

 foundation. When on the Kentish Knock Light- 

 ship, Mr Eagle Clarke noticed, on a bad day, east 

 to west migrants hurrying past ' as if to avoid as 

 much as possible the effects of the high-beam 

 wind." 



Mr A. H. Clark worked out the long oversea 

 and overland course followed by the American 



ts 



golden plover, and showed to his own satisfaction 

 that the birds always travelled at right angles to 

 the prevailing winds ; therefore, he argued, they 



