lO E. L. THORNDIKE. 



^ inch thick. This turned on a nail driven into the box % 

 inch above the middle of the top edge of the door. The door 

 would fall inward as soon as the button was turned from its 

 vertical to a horizontal position. A pull of 125 grams would 

 do this if applied sideways at the lowest point of the button lyi^ 

 inches below its pivot. The cats usually clawed the button 

 round by downward pressure on its top edge, which was i )i 

 inches above the nail. Then, of course, more force was neces- 

 sary. C may be called 'Button.'' 



D. The door was m the extreme right of the front. A 

 string fastened to the bolt which held it ran up over a pulley 

 on the top edge and back to the top edge of the back side of 

 the box (3 inches in from the right side) and was there firmly 

 fastened. The top of the box was of wire screening and 

 arched over the string ^ inch above it along its entire length. 

 A slight pull on the string anywhere opened the door. This 

 box was 20 X 16, but a space 7 x 16 was partitioned off at the 

 left by a wire screen. D may be called ' String.' 



Di was the same box as B, but had the string fastened 

 firmly at the back instead of running over a pulley and ending 

 in a wire loop. We may call it ' String 2nd.'' 



E. A string ran from the bolt holding the door up over a 

 pulley and down to the floor outside the box, where it was 

 fastened 2 inches in front of the box and i % inches to the left 

 of the door (looking from the inside). By poking a paw out 

 between the bars and pulling this string inward the door would 

 be opened. We may call E 'String outside.' 



In F the string was not fastened to the floor but ended in a 

 loop 2 yi inches in diameter which could be clawed down so as 

 to open the door. Unless the pull was in just the right direc- 

 tion, the string was likely to catch on the pulley. This loop 

 hung 3 inches above the floor, and i ^ inches in front of the 

 box. We may call F 'String outside unfastened.'' 



G was a box 29x20^ x 22^, with a door 29 x 12 hinged on 

 the left side of the box (looking from within), and kept closed 

 by an ordinary thumb-latch placed 15 inches from the floor. 

 The remainder of the front of the box was closed in by wooden 

 bars. The door was a wooden frame covered with screening. 



