54 THE FLIGHT OF BIRDS 



evidently doing, the feat of an almost vertical 

 ascent. 



The big and bulky birds then, such as the Gannet 

 and the Condor, having a much slower wing-stroke 

 than the light-weights, must make it their first 

 object to attain momentum, otherwise they will 

 lose altitude between the strokes. When they 

 have got way on, they can rise, but the line of their 

 ascent is a gentle slope. For a steeper ascent the 

 set of their wings unfits them. But there are birds 

 of medium size, such as the Duck and the Pheasant, 

 which, striking with very great rapidity and rotating 

 their wings as freely as any small bird, are capable 

 of raising themselves almost vertically through 

 the air. 



Aeroplanes. 



In a country like England, with trees and hedges 

 almost everywhere, an aeroplane capable of a 

 steep ascent is a great desideratum. Captain 

 Brooke- Popham, writing on military aviation, says 

 that " with no wind a fully-loaded machine, with 

 observer, could get off a hard level field in a length 

 of 120 yards and clear a fair hunting hedge at the 

 end. Our Air Battalion " Farman " can do this 

 in 90 to 100 yards without any difficulty."* Thus 

 even the " Farman " requires a great deal more 

 space than a Condor or a Comorant, birds noted 

 as slow, lumbering starters, and though aeroplanes 

 are constantly being improved it may well be 

 doubted whether a steep ascent will ever be 

 achieved. 



* The Army Review, January, 1912, p. 89. 



