96 Tin; Wilson BULLETIN — No. 52, 



were carried well in front of the body when the blow was deliv- 

 ered, the bird assuming a perpendicular position while drum- 

 ming. Such a strong downward stroke would seem likely to 

 drive the bird into the air. 1 have tried to produce the sound 

 by striking a wing against a surface like a log or stone, and 

 failed to produce more than a faint echo. Striking the wing 

 against feathers upon a bird's body produced no better results. 

 Some have argued that the wings striking together would pro- 

 duct- the effect. 1 am not prepared to say that the wings do 

 not touch ; possibly they do, but feathers striking together could 

 hardly produce the strong concussion which the drumming is 

 accompanied by. When one is within twenty feet of the per- 

 forming bird the concussion is sufficient to force the clothing 

 against ones body as the discharge of a cannon does. This 

 concussion must be accounted for by the advocates of the theory 

 that the bird produces the sound by expelling air from the 

 lungs at the instant of the wing stroke. Does not the concus- 

 sion of the air forced out from between the wings by the great 

 force of the stroke produce the boom? 



