196 ACCOUNT OF THE ARCTIC REGIONS. 



On the occasion when the marine-diver was lost, 

 I had a very extensive and improved experiment in 

 view, on the effect of the pressure of the sea, at one 

 of the greatest depths ever sounded. Attached to 

 the apparatus, were specimens of wood and other 

 substances, to the amount of twenty articles, all 

 carefully weighed and adjusted, that the increase of 

 specific gravity might be accurately determined. 

 This failing, however, by the breaking of the line, 

 I repeated the experiment on the 18th July 1818 ; 

 but having no apparatus for bringing up the water, 

 or for ascertaining the temperature below the sur- 

 face, my object was confined solely to the effect of 

 pressure. Finding, on former trials, that pieces of 

 fir wood sent down 4000 feet, were more impreg- 

 nated with sea-water than others immersed only 

 half that depth, I was in hopes that the degree of 

 impregnation of similar pieces of the same kind of 

 wood, might be applicable as a measure of depth. 

 If this were the case, it would serve a very valuable 

 purpose, since all the plans hitherto contrived for 



weight of a cubical inch of the same, at the usual temperature 

 of the sea. This, multiplied by 12, gives the weight of a co- 

 lumn of sea- water, an inch square and a foot long, equal to 

 3114.91 grains; which, multiplied by 4566 feet, the depth to 

 which the specimens of wood were sent, and divided by 7004, 

 the number of Troy grains in a pound Avoirdupois, affords 

 the result of 2030.65 lb. for the weight of a column of water an 

 inch square, and 4565 feet high. 



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