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HAROLD C. BINGHAM 



of E. When E is closed S is extended and in a state of torsion, 

 hence when E is released S tends to return to a state of rest 

 and the doorway is opened. The method of closing the door- 

 way may best be seen in figure i . A silk line, e, which passes 

 up "through a wire loop directly under E is attached to the 



Figure 3. Automatic tripping device of the experiment box. 



lower part of the door. By pulling on e the experimenter can 

 close E which automatically locks when it is closed. By step- 

 ping on or striking T the chick can release the lock. The ex- 

 perimenter, however, by catching e on the hook h can prevent 

 the door from opening when the T-lock has been released. This 

 automatic release was devised by Professor F. S. Breed. 



