116 ILLINOIS ACADEMY OF SCIENCE 



from those of others more emphatically inclined in this 

 direction. 



Apparatus. It was onr task to reproduce on a smaller 

 scale and under laboratory conditions the effect de- 

 scribed in the above reports. That the appearance was 

 startling- and beautiful most of our observers spontane- 

 ously remarked. Twenty small, 15 watt tubular incan- 

 descent lamps were mounted irregularly over a wooden 

 framework on candelabra bases. Covers for these lights 

 were then made out of mailing tubes with one end sealed 

 and a hole punched in this end in diameter a little larger 

 than that of the ordinary pin-hole. The inside of the 

 tubes was lined with white bristol board to increase the 

 reflection. But great care was taken to stop all light- 

 leaks, even thoes only faintly visible in the dark-room. 

 The entire arrangement subtended a visual angle of 

 about 25°, the observer sitting about 5 meters away from 

 the framework. The framework was eccentrically pivoted 

 on the wall opposite the observer so as to disturb any 

 tendency to memorize the pattern of arrangement. When 

 the experiment was not under way, a curtain hung over 

 the apparatus in order to prevent the possibility of an 

 inadvertent exposure of the apparatus to the observer. 

 There was provided also a small greenish light mounted 

 near the center of the framework which served to give 

 the observer the approximate center of fixation. A tele- 

 phone cable with a separate strand for each light carried 

 the connections to an adjoining dark-room where the 

 experimenter was stationed and where the control ap- 

 paratus was located. This consisted principally of a 

 small horizontal brass drum driven by a very smoothly 

 running clockwork and governor. On the drum were 

 mounted strips of paper with perforations for the con- 

 tacts made through twenty separately connected point- 

 ers. Whenever one of the pointers passed over a hole 

 in the paper the electric circuit for its particular lamp 

 was closed and the lamp would flash. A main switch 

 and a switch for the momentary flashing of the fixation 

 lamp completed the apparatus in the experimenter's 

 room. 



