79 
1891-92.] Mr R. W. Western on the Tactics of Birds. 
absolute maximum. Substituting in this the values for W and A 
already given, we obtain *0237. So that the falling bird at the 
end of the first second will have attained a velocity only 2J per 
cent, less than its greatest possible value. 
It is, however, also necessary to find how far the bird will fall 
in a given time. We must, therefore, evaluate 
Putting ^ = 1 in order to find the distance fallen during the first 
second, we see that the middle term becomes so small that it may 
be neglected. Then, substituting the proper value for W and A, we 
have 
14*5 X -*386= -5-6 
or about 5 feet 7 inches in a downward direction. 
Por the next and succeeding seconds the drop, as we have seen, 
will exceed 14 feet. 
Actual experiments on dead birds, with their wings extended with 
wire (correction being made for the increase of weight), more than 
confirm these results, and entirely dispose of the parachute theory 
as applied to these birds. We must, therefore, look to another 
principle to explain the support they derive from the air they fly 
in. 
Such a principle is furnished in the example of a common paper 
kite. As everyone knows, the two essential conditions for making 
the kite to rise are, wind and string, of which a bird must necessarily 
lack the string. Por this reason the bird can make no great use of 
this principle in a -wind of constant velocity. When, however, the 
