95 



resistance to his progress through the air, due to his own speed 

 being greater than that of the breeze at his back. It hence 

 follows that if these Crows turn their bodies to the south to 

 escape the disagreeable experience of the wind blowing obliquely 

 through their plumage from behind, that they must be travelling 

 at a lower rate of speed than the latter to produce this effect. 



After reading for the first time and reflecting upon these 

 high estimates of the velocity attained by birds, as put forward 

 by Herr Gatke, the writer thought it would not be uninteresting 

 to time the number of wing-beats per minute performed by 

 the present species during its daily flight, under ordinary condi- 

 tions. Eepeated observations gave a result of from 190 to 200. 

 If we take the latter number as the basis of a simple calculation, 

 we shall get as a further result 12,000 beats accomplished in 

 an hour, during which period, in the light of Herr Gatke' s 

 estimate, 108 geographical miles should be covered or at the 

 rate of sixteen yards for each wing-stroke. Now the latter him- 

 self has classed the Hooded Crow amongst the less expert flyers. 

 But a speed covering a distance of sixteen yards for each 

 beat of the wings, or forty-eight yards per second which, as has 

 already been pointed out, is necessary to accomplish a flight of 

 108 miles an hour would have the appearance of a very swift 

 gliding motion. The latter is certainly not the character of the 

 flight of the Hooded Crow, nor could such a flight be classed as 

 other than expert. 



Turning now from a robust bird like the Hooded Crow, to 

 a dainty species of less than one-eighth its bulk, and to which 

 Herr Gatke attributes the power of attaining a still higher and 

 more incredible velocity of flight during its annual journeys, i.e., 

 the Northern Bluethroat. This is said to reach the astonishing 

 speed of 180 miles an hour, in the case of the flocks passing 

 Heligoland, and a still greater velocity in other instances. There 

 is no other species to which Herr Gatke makes more frequent 

 reference throughout his work than to this charming bird. It 

 will, therefore, .be interesting to here sum up the full extent of 

 the performances it has to undertake in order to accurately fulfil 

 all his speculations. 



The more the latter are studied, the more involved in 



