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 

 Avood thrown aside to be nsed 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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