From Don Michels
The question of whether a truck becomes lighter if its cargo of birds takes flight was answered definitively in 1961 by some fellow graduate students at the Colorado School of Mines (24 January, p 13).
We captured a honeybee in a small glass jar with a tight-fitting lid and placed the assembly on a scale that was sensitive to 0.1 milligrams. With the lid on tight, the balance was absolutely steady, regardless of whether the bee was clinging to the sides or hovering.
However, when we loosened the lid, the balance was lighter when the bee was hovering.
Missoula, Montana, US
