34 



G. V. HAMILTON 



the facts relevant to it. With this in mind I have made use of 

 the apparatus and method described below. 



Description of apparatus. The reader will more clearly under- 

 stand the purpose of the apparatus by picturing to himself a 

 room which may be entered by a door capable of giving entrance 

 only, and which may be gotten out of by means of a constantly 

 varying one of four possible doors of exit. Let us then imagine 



EH 



ENtD 



Figure 1 — Floor plan of apparatus. EntD, Entrance Door; O, point of equidis- 

 tance from exit doors; ExD 1, ExD 2, ExD 3, ExD 4, Exit Door number 1, 

 Exit Door number 2, etc. 



that from within the room one may see on each of the five doors 

 a distinctive inscription, as follows: 



Entrance door : cannot he used for exit. 



Exit door No. i : push against it; will afford exit unless it is locked. 



Exit door No. 2 : (same inscription). 



: (same inscription) . 



.: (same inscription) . 



The apparatus differs from this imaginary room in that its 

 various doors are not labelled at all, and are all alike in appear- 

 ance, so that a subject seeking exit from the apparatus must 



Exit door No. 3 : 

 Exit door No. 4: 



