4 BULLETIN 1328, U. S. DEPARTMENT OF AGRICULTURE 



be. The bee having left the tunnel, the counterbalance now has a 

 greater moment than the empty tunnel, the second door is closed, 

 contact is broken, and the first door is opened, so that the mechanism 

 is now ready to count the next bee. This seesaw motion continues 

 as long as bees are passing through the tunnel. The illustration 

 (fig. 1) shows an incoming gate. The only difference between this 

 and an outgoing gate is the presence of glass immediately in front 

 of the tunnel on the outgoing gate, and a different position of the 

 binding posts. The tunnels adopted after some experimentation 

 were 15 millimeters long, from 6.5 to 7 millimeters wide, with a 

 curved upper portion from 4.5 to 5 millimeters at the highest point. 

 These were so adjusted that a 67-milligram weight placed at the 

 base of the rear door brought the tunnel down to the lower stop. At 

 other times 75-milligram and 47-milligram weights were used, but 

 most of the data were obtained with the first-mentioned adjustment. 



Fig. 1. — Apparatus for recording by electrical contact the ingress of bees into 



the hive 



Since this device, in the course of this investigation, has shown 

 certain undesirable features, it remains, in a search for the ideal 

 counting device, to consider briefly the possibility of counting bees 

 by means of the amplification of a current whose circuit is closed 

 by the body of the bee itself. 



In discussing the possibility of this method with the writer, radio 

 experts have suggested that it might be better to get the bee to pass 

 between the plates of a small condenser and thus to vary its dielectric 

 constant, and then to use this variation to record the passage of the 

 bee. Assuming that expense is of no consideration, it is still ques- 

 tionable whether this method would have any advantage over the 

 one used in this investigation. Some device would be needed before 

 and after the condenser to regulate the passage of the bees, and these 

 obstructions might be as great as or greater than that offered by the 



