8 BULLETIN 1328, IT. S. DEPARTMENT OF AGRICULTURE 



For convenience in compiling the data, the quarter-hourly read- 

 ings were recorded by means of a typewriter on cards of three differ- 

 ent colors, blue being used for the outgoing data, yellow for the 

 incoming data, and white for all other records and general notes. 

 The differences between the successive readings and other data were 

 obtained at a later date by the use of an adding machine. The 

 long days, with frequent observations and the dismantling and 

 cleaning of some of the gates in the evenings to get the apparatus 

 ready for the following day, not only necessitated two observers 

 but also rendered it impossible to make compilations during the 

 active season of work. 



FACTORS INTRODUCING ERRORS IN THE COUNT 



With any untried experimental mechanism consisting, as this 

 did, of many units, each unit in turn possessing parts having defects 

 either of construction or of design, it is too much to expect perfect 

 accuracy during the first season. Before discussing the magnitude 

 of the experimental error produced by these deficiencies, it is desir- 

 able so far as possible to know the manner in which this error arises. 



1. After observing the passage of about 2,000 bees through the 

 early experimental model, it was thought that a tunnel had been 

 devised which although allowing only one- bee to pass at a time, 

 would cause little inconvenience to the insect and would avoid as 

 much as possible the scraping off of the load of pollen as the bee 

 passes through the device. However, further experience with the 

 full set of gates on the hive showed that some of the tunnels would 

 occasionally allow two bees to pass at one time. Sometimes the two 

 bees would get through and establish only one electrical contact, but 

 they might cause two or even more contacts because of the irregular 

 manner in which the tunnel fell under their weight, the movement 

 being impeded by the pressure of their bodies against the stationary 

 surfaces of the apparatus. Under normal weather conditions this 

 difficulty was confined almost entirely to the outgoing gates, as the 

 stimulus urging the bees into the outgoing channels was apparently 

 much stronger than that attracting them into the ingoing tunnels. 

 By darkening the glass windows and reducing the dimensions of the 

 tunnels, this error was reduced to a minimum. Rebuilding all these 

 tunnels was a tedious operation, consumed a great deal of time, and 

 could be done only gradually, so that the early records show a 

 greater error from this cause than the later ones. 



2. Rebounding of the empty tunnel so as to form a second contact 

 occurred occasionally if the adjustment of the counterweight was too 

 delicate or if it had been rendered so by debris or pollen collecting 

 in the tunnel. 



3. Debris dropped or propolis placed by the bees in the clearance 

 between the movable and stationary parts may cause double con- 

 tacts by slowing down the speed of the tunnel in its fall; but when 

 the quantity of debris became so large that the tunnel ceased to 

 function, no error was introduced. 



4. The voltage made necessary by the adoption of the telephone- 

 message register unfortunately caused a considerable amount of oxi- 

 dation on the surface of the mercury through arcing. In spite of 

 frequent cleaning of the surfaces of mercury, this occasionally gave 



