74 



K. S. LASHLEY 



After some preliminary tests a combination-latch box was 

 constructed which seemed to meet the above requirements. 

 Its general plan is shown in figure 2. It consisted of the usual 

 square, wire-covered box with a door (d) which opened inward 

 by the pressure of a spring. The door was held closed by latches 

 attached to two metal platforms (a and 6) at opposite ends of 

 the box. The platforms were 10 cm. long by 5 cm. wide and 



FIG. 2. THE DOUBLE-PLATFORM Box 



a and 6, platforms which must be pushed down in the order a-6 in order to 

 open the door, d, to the food box. 



2 cm. above the floor. Their inner ends were hinged to the 

 sides of the box and arranged to release the latches when their 

 outer ends were depressed. By adjustable springs under the 

 platforms the weight required to depress them could be regu- 

 lated. Throughout the experiments they were adjusted so that 

 a weight of 50 grams would just release the latches. The door 

 was placed in the side of the box near one end. Pressure on 

 the platform at that end (a) released one latch and allowed 



