194< ACCOUNT OF THE ARCTIC REGIONS. 



and its attached pieces, were under water, by the 

 way of distinguishing the degree of impregnation 

 produced by pressure, from the absorption which 

 takes place from ' simple immersion. On being 

 brought up, they were all specifically heavier than 

 sea-water ; and, when compared with the counter- 

 parts, the clear effect of impregnation by pressure... 

 was found to be 302 grains in the fir and hickery, 

 and 316 grains in the ash. This experiment was 

 repeated in latitude 78° 2', on the 7th June 1817, 

 by the immersion of several articles of different 

 shapes * and sizes, to the depth of 4566 feet. On 

 this occasion, the apparatus was 30 minutes on its 

 way down, rested 40 minutes, and took 36 minutes 

 in drawing up, being altogether 106 minutes under 

 water. The degree of impregnation produced on 

 ^ach of the different substances used in this expe- 

 riment, is stated in the annexed Table. 



* My friend Professor Leslie suggested this variation of 

 trying the relative degree of impregnation, on pieces of the 

 same kind of wood, of different shapes ; — a hint w^hich I pro- 

 fited by in my later experiments. 



