WILD ANIMALS IN CAPTIVITY 
an impression that the beaver uses its tail as a plasterer 
does his trowel in building his dam ; this idea is entirely 
erroneous, the tail being used as a rudder in swimming, 
rising, and diving in the water, but the most extraordinary 
use is the warning given to the rest of the family by the loud 
report his broad tail makes on the surface of the water, of 
a supposed danger, for however many there may be about^ 
upon this signal they all disappear under water. The 
sound is so remarkable, that upon a still night it could 
probably be heard halfa-mile away. 
100 
