206 ON SOARING FLIGHT. 



Unquestionably the problem presented by the soaring- birds is a diffi- 

 cult one, as the air in which the bird moves is invisible, our knowledge 

 of its movements is limited, and the bird himself must be studied from 

 a distance. No solution amounting to a demonstration can at present, 

 therefore, be looked for. Nevertheless, some sort of a solution is desir- 

 able if only to give direction to our investigations, and the proposed 

 solution here given of flight in light winds, if it should prove to be the 

 correct one, opens up possibilities of artificial flight which can scarcely 

 be overestimated, for the sources of power which enable the bird to fly 

 with so little expenditure of its energies are all perhaps equally avail- 

 able for man in artificial flight, since the maneuver of flying in circles 

 is very simple and is one which could be easily reproduced. 



