Automatic Photography by Electricity 33 



corded its presence and aj)])earaiK'e on a sensitive plate 

 without kno\vint>* tliat anything- lias happened. A permanent 

 record of the bird's appearance has been obtained without 

 any sacrifice of life or the suffering of any pain. 



'I'he varied natiu'c of the positions selected by birds 

 makes it impossible to depend upon any one particular 

 method of using or releasing the automatic photo-trap. 

 AN'hat is possible on the ground, for instance, is not by 

 any means practicable up a tree ; and there is ])lenty of 

 occasion for all one's resource and ingenuity. In the case 

 of water-birds it should be possible, on a small and narrow 

 stream, to stretch a silk thread from bank to bank just 

 above the surface of the water, so that any swimming bird 

 Avould touch it in passing and complete the electric circuit. 

 There is, in fact, no end to the devices which may be 

 made use of in this branch of work. It is hardly necessary 

 to say that the greater ones knowledge of the habits of 

 birds the greater chance there is of success. 



It is ([uite possible to induce some birds to perch upon 

 any twig you may select, or to put a twig or l^ranch on 

 purpose for them to sit on, with every chance of their 

 acceptance of your invitation. AMiinchats, Butcher-birds, 

 and Spotted Flycatchers, for instance, are fairly easy to 

 manage in this respect, and I have succeeded in persuading 

 Nightingales to settle where I wished. Some species seem 

 to be gifted with abnormal acuteness of sense. \A"ater-hens 

 are as difficidt as any birds I know to circumvent. When 

 you are expecting them to approach by water, they are in 



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