20 
BULLETIN 1328, U. S. DEPARTMENT OF AGRICULTURE 
the wind velocity was as high as 14 to 17 miles per hour. Again, 
on May 19 (fig. 6), a day when the morning's weight was all but 
regained at the end of the day, a wind of 9 to 10 miles per hour, 
from 8 a. m. to 4 p. m., apparently scarcely affected the flight, which 
was greater by 54 returns than on the following day when the wind 
velocity was only 1 to 4 miles per hour. On these two days the 
wind velocity was taken from an anemometer about 5 feet from the 
ground and about 20 feet from the hive. 
The only other windy day of any consequence — ^June 22, a day in 
the dearth — during which from 9 a. m. to 6 p. m. the wind varied 
from 16 to 21 miles per hour shows a reduction of 28.53 per cent in 
Fig. 8. — Flight, temperature, and hire-weight data for May 20, 1922, a day in 
a time of honey flow 
the total day's flight, when compared with June 23, a day Avith 
little or no wind. The wind velocity on the former day is taken 
from the data obtained by the AVeather Bureau in Washington at a 
higher elevation from the ground. 
THE EFFECT OF TEMPERATURE 
It is only when all the factors influencing flight but one are at 
least at an intensity favoi-able for flight, and this last factor is 
increasing in intensity toward this condition, that its minimum in- 
tensity can be determined. Any. one factor can become the lagging 
factor at one time or another. In the early part of the season tem- 
perature is this factor more often than any other. 
