vu FLIGHT 217 
equally certain with regard to less flurried flight. 
The slowness of a bird’s. stroke compared with an 
insect’s was most remarkable, a common fly attaining 
the astounding rapidity of 330 per second, and.a bee 
190. It must. be borne in mind that the extremity of 
a long wing may move very rapidly, though the number 
of strokes per minute be few, and that a bird’s wing 
with its long sweep may produce more effect, even 
when we allow for the greater weight to be supported 
and propelled, than the insect’s can by its many rapid 
pulsations. 
There is the further question of the comparative 
velocity of the up- and downstrokes. Photography 
thas proved what we should not have anticipated—viz., 
that the upstroke is the more rapid of the two. 
Duration of Duration of 
upstroke. downstroke. 
3 33 
Duck ... ies ee a. = sec. 23 sec. 
60 60 
Pigeon veh is . »& sec, 4B sec. 
8 60 60 
I 
Buzzard. 3 sec, 13 sec. 
60 60 
This is accounted for by two facts —(1) that the 
air offers little resistance to the passage of the rounded 
upper surface; (2) that when the pace attained is great 
the air itself lifts the wing and relieves the Elevator 
muscle of a great part of its work. 
1 See Marey’s Vol des Oiseaux, p. 101. 
