THE ARCTIC SEAS. 149 
been known to descend perpendicularly to the depth 
of a mile, as measured by the length of line “run 
out;” where the pressure of the immense body of 
water above would be equal to a ton upon every 
square inch. And Mr. Scoresby mentions a case in 
which a boat that was accidentally entangled was 
carried down by the Whale, which was presently 
captured, and the boat recovered by being drawn up 
with the line; but from the intense pressure, the 
water had been forced into the pores of the solid 
oak, so that it was completely saturated, and sunk 
like lead: the paint came off in large sheets, and the 
wood thrown aside to be used as fuel, was found to 
be useless, for it would not burn. A piece of the 
lightest fir-wood, which was in the boat, came up in 
exactly the same soaked condition, having totally 
lost the power of floating. To resist such a pressure 
as this, the blow-holes of the Whale tribe are closed 
with a valve-like stopper of great density and elasti- 
“city, somewhat resembling India-rubber, which, ac- 
curately fitting the orifice, excludes all water from 
the windpipe, becoming more tightly inserted in 
proportion to the pressure. 
But this precaution would be vain, if the structure 
of the interior of the mouth were the same as in 
other Mammalia. Usually the windpipe and gullet 
open into a hollow at the back of the mouth, and 
the passage to the nostrils proceeds from it likewise. 
The windpipe passes up in front of the gullet, and 
the food which passes over the former is prevented 
from entering it by a lid or valve, which shuts down 
during the act of swallowing, but at other times is 
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