THE FLIGHT ACTIVITIES OF THE HONEYBEE 9 



some trouble in case the mercuric oxide collected as a flocculent mass 

 on the platinum points. Under such circumstances the weight of the 

 bee is no longer sufficient to overcome the greater displacement of 

 mercury now necessary, and multiple contacts may result. This 

 error was apparently eliminated by adjusting the apparatus so as 

 to bring the mercury cups closer to the fulcrum, giving the bee a 

 greater moment than this opposing force. 



5. The bees about to enter the tunnel may push against the closed 

 inner door (especially if its clearance is large) and may occasionally 

 produce multiple contacts when the tunnel is either on its downward 

 or on its upward stroke. 



6. A bee pushing hard against the glass of an outgoing gate may 

 produce multiple contacts by preventing a tunnel from falling 

 rapidly past its critical point. Errors from this cause and from 

 pushing against the closed inner door were very much reduced by 

 darkening the glass on the gates (p. 8). 



7. Bees clawing at the closed outer door of the device may bring 

 the tunnel down far enough to form an electrical contact, especially 

 if the doors are roughened by dirt or propolis or by a corrosion of 

 the surface of the metal. Error from this source was peculiar to the 

 ingoing gates, for on only two occasions was it observed on an out- 

 going gate. An attempt was made to eliminate this source of error 

 by placing small metal cups over the exit hole so that clawing could 

 take place only in an upward direction. 



8. The segments of some of the recording cyclometers would some- 

 times bind against each other, thus failing to record the contacts 

 when the magnet was excited by the passage of a bee. This necessi- 

 tated some readjustments of the cyclometers. 



9. The cleaning of the gates in the evening, after the day's records 

 had been taken, necessitated the use of an artificial light, which on 

 warm nights attracted some bees from inside the hive. These might 

 remain outside all night, thus introducing an error on the following day. 



10. The clustering out of the bees in the warm weather following 

 the main honey flow was one of the most disturbing features of this 

 investigation. On many days, records which were normal during 

 the early part of the day were rendered valueless later on through 

 the clustering out of the bees in the afternoon. At the same time 

 this clustering out occurred throughout the apiary. 



11. In the construction of the outgoing gates a small strip of metal 

 was left between the outer aperture and the lower edge of the glass 

 window, which was sometimes grasped by the bee in its fall, giving 

 rise to multiple contacts. 



12. A small error was caused by the actual drifting of the bees. 

 This was apparent on colder mornings when the other hives in the 

 apiary were active and the experimental one had not yet commenced 

 its activity. 



It is clear from the preceding list of causes of errors that with the 

 exception of No. 8, and sometimes of No. 1, all these factors have a 

 tendency to increase rather than decrease the recorded exits and 

 entrances of the bees. With the experience gained in the 1922 

 Beascn in the design and handling of this apparatus, the writer is 

 convinced that, with the exception of Nos. 2 and 3, where debris is 

 the cause of error, all these factors may eventually be eliminated. 

 2f;!»00 o — 2r> 2 



