72 GAME-BIRDS OP INDIA 



observer's head and a typical bleat is produced. The second outer 

 tail feathers (sixth pair) produce a fainter sound ; though this varies 

 much in individual tails, the others make no sound at all. 



" In order to ensure the success of the experiment, it is necessary : 

 (l) that the feathers be placed so that the narrow edge — the outer 

 web — shall encounter the resistance of the air ; (2) that the feather 

 be firmly bound to the pin, so that it cannot turn on its support ; 

 (3) that the string be tied to one end of the stick, so that the long 

 axis of the stick makes an angle with the direction of the string, if I 

 may so put it, so that a vibratory motion is imparted to the stick as 

 a whole, thus simulating the tremulous motion of the snipe's wings 

 during the descent ; (4) lastly, that the apparatus be moved at a 

 uniform rate, and not too fast. 



It is then found that after a period of silence tlie feathers begin 

 to vibrate ; first, the long drawn-out note, which I may represent as 

 ' WhiL, Whu, UU,' becomes gradually audible ; it is then succeeded 

 by a series of high and low notes, 'Bah, Bah, Ah, Ah,' resembling 

 the bleat of a young goat, lasting three to five seconds, followed by 

 a pause of equal length. This is repeated as long as the apparatus is 

 revolving at a uniform rate. It is found that the individual tail 

 feathers, of which I collected a good number during the winter, vary 

 considerably both in size, breadth, and markings, and, as might be 

 expected, the note produced varies according to their physical 

 characteristics. Thus a long narrow feather produces a sound of far 

 higher pitch than a broader one of the same length. This fact I 

 have noted when comparing the sound made by the several birds 

 when performing the nuptial evolutions over the breeding ground. 

 To ascertain which part of the feathers is essential in the production 

 of the sound, I have cut off the narrow outer web without altering 

 the bleat in any way ; but if the barbs of the inner web be so 

 disarranged that there is a break in their continuity, the web ceases 

 to vibrate, and no sound is produced. That the vibration of the 

 inner web is the active causative agent may be seen by the following 

 simple experiments. The feathers are attached to a cork with the 

 outer web held away from the observer, so that the narrow outer 

 web shall meet the resistance of the air. Thus affixed, they are held 

 out of the window of a train or while riding a bicycle. As the 

 resistance of the air is encountered, the inner web begins to vibrate, 

 slowly at first, but, as the train gains speed, so rapidly that its outline 

 is entirely lost and it becomes blurred ; a low humming sound is at 

 first heard, which soon reaches the typical pitch of the bleat. When 

 the train has reached the speed of some twenty miles an hour, the 

 whole feather will vibrate on the pin. If the feathers are at all loose 

 on their pins, it is curious to observe how they will always turn round, 

 so that tlie narrow outer edge encounters the resistance of the air. 



