HELIOTBOPIC MACHINE 69 



The orientation mechanism here mentioned possesses two selenium 

 cells corresponding to the two eyes of the moth, which when influenced 

 by light effect the control of sensitive relays instead of controlling 

 nervous apparatus, as is done in the moth. The two relays (500 to 1,000 

 ohm polarized preferred) controlled by the selenium cells in turn control 

 electro-magnetic switches, which effect the following operations: When 

 one cell or both are illuminated the current is switched on to the driving 

 motor; when one cell alone is illuminated an electro-magnet is energized 

 and effects the turning of the rear steering wheel. The resultant turning 

 of the machine will be such as to bring the shaded cell into the light. 

 As soon and as long as both cells are equally illuminated in sufficient 

 intensity, the machine moves in a straight line toward the light source. 

 By throwing a switch, which reverses the driving motors, the machine 

 can be made to back away from the light in a most surprising manner. 

 When the intensity of the illumination is so decreased by the increasing 

 distance from the light source that the resistance of the cells approach 

 their dark resistances, the sensitive relays break their respective circuits 

 and the machine stops. 



The principle of this orientation mechanism has been applied to the 

 " Hammond Dirigible Torpedo " for demonstrating what is known as 

 attraction by interference. That is, if the enemy tries to interfere with 

 the guiding station's control the torpedo will be attracted to him, etc. a 



Nothing seems to have been published beyond these 

 meagre details, but the writer understands that the active 

 machine has been demonstrated in a number of places in 

 this country. It seems to the writer that the actual con- 

 struction of a heliotropic machine not only supports the 

 mechanistic conception of the volitional and instinctive 

 actions of animals but also the writer's theory of helio- 

 tropism, since this theory served as the basis in the con- 

 struction of the machine. We may feel safe in stating 

 that there is no more reason to ascribe the heliotropic reac- 

 tions of lower animals to any form of sensation, e.g., 

 of brightness or color or pleasure or curiosity, than it is 

 to ascribe the heliotropic reactions of Mr. Hammond's 

 machine to such sensations. 



a Electrical Experimenter, September, 1915, 202. 



