2 BULLETIN 1328, U. S. DEPARTMENT OF AGRICULTURE 
While reading an interesting paper by Leon Dufour,- in which 
are shown the great variations which the weight of a hive under- 
goes in the course of a single day, the writer, seeing how the in- 
coming nectar and pollen modified the interpretations of the 
flights which occurred, realized more fully the scientific value of an 
automatic apparatus which would register the exits and returns of 
the individual bees, and was led to spend the greater part of the 
winter of 1921-22 in devising an apparatus for this purpose. 
Actual recording of individual flights was begun on April 8, 1922, 
with 14 units of the apparatus in place. On May 10 the full quota 
of 30 instruments was installed and readings were continued regu- 
larly, including Sundays and holidaj-s, from daylight to dark, until 
July 29, except for six days, when the work was interrupted by 
certain necessary modifications or adjustments of the apparatus. 
During this period some five million flights to and from the hive 
were recorded, the gross weight of the bees representing half a ton. 
Since the first object of this experiment was to determine the prac- 
ticability of obtaining data on problems pertaining to the flight of 
bees by means of an automatic recording mechanism, rather than to 
make a study of any one of these problems, and since there appears 
to be no immediate opportunity for the writer to continue this in- 
teresting line of investigation, it seems best to record the data so 
far obtained, that they may serve as at least an introduction to a 
further study of this phase of bee behavior. 
THE APPARATUS 
At the outset it was clear that, on account of the limited space at 
the hive entrance, the most practical apparatus for counting the 
flights of bees would be one in which each bee would establish elec- 
trical contact as it left or as it entered the hive. Any such appa- 
ratus must consist of as man}^ units as will accommodate the full 
flight of the colony under experimentation, each unit consisting of 
one contact device and one recording mechanism. 
THE CONTACT DEVICE 
A device for establishing electrical contact's that will give the de- 
sired data is one which requires for its operation little or no exertion 
on the part of the bee and which will delay the bee A'ery little or 
not at all in its departure or return. To meet these requirements 
there are at least three possible methods of approach, arranged here 
in the ascending order of their complexity and expense. 
(1) To alloAv the bee to push against some mechanism. 
(2) To allow the weight of the bee to operate some mechanism. 
(3) To use a minute electric current, the circuit of which is closed 
by the body of the bee itself as it passes the terminals, but not strong 
enough to cause any modification of behavior, and then to amplify 
this current so as to operate the recording mechanism. 
Working on the plan of allowing the bee to push against some 
mechanism, a modification of the ordinary bee-escape which alloAvs 
bees to pass but one way was tried. A small wire was soldered at 
- Dufour, L^on. Travail des butineuses et r^colte du miel. In L'ApicuIteur, vol. 41, no. 
8, pp. 300-312. 1897. 
