GEOLOGICAL SOCIETY OF MANCHESTER. 



209 



of 2,000 miles, extending from Canada to Florida. The 

 soil of Persia is also said to contain gravel, consisting of 

 flint and gypsum. The only positive notice that I am aware 

 of, of the absence of boulders, is by Humboldt, in South 

 America, which appears to favour the opinion of that region 

 being of subsequent origin to the glacial epoch. 



TVith regard to the vexata qu(Ebtio, the temperature of the 

 greatest density of sea water, Scoresby remarks, page 238, 

 of his Voyage to Greenland : — I have invariably found it 

 to be warmer below than at the surface. This exception, 

 therefore, is remarkable, referring to an experiment before 

 mentioned, in which he found the temperature at the surface 

 to be 34^ Fahrenheit, while within five fathoms of the bot- 

 tom, the thermometer registered 29°. " On my first trial,^^ 

 he says, "made in the summer of 1810, in lat. /6'° 16^; 

 long. 9° east ; the temperature, at the depth of 1.380 feet, 

 was found to be 33° V (by the water brought up), whilst at 

 the surface it was 28° 8'.^' This experiment is detailed in a 

 tabular form, in the first volume of his account of the 

 Arctic Region, page 1 8/, as follows : 



Lat. Lon. Depth in ft. Tem. S. grav. Colour. Tem. Time, ^ g 



of air. •-' 



76 16. . 9. . Surface. .28 8. . r026l*. . Blue, 12. . IQth April, 1810 



76 16. .9.. 300 .31 8.. — .. Blue. . 12.. 19th April, 1810 ^ I 



76 16. . 9. . 738 . . 33 8. . 1-0270 . . Blue. . 12 . 19th April, 1810 



76 16. . 9. . 1,380 . . 33 3. . r0269 • . Blue. . 12. . 19th April, 1810 J ^ 



The specific gravity of the sea in lat. 76° 16' strictly coin- 

 cides with the conclusion, that the water of the ocean 

 increases in density in a similar manner with fresh water. 

 We find also, from the above table, that at the depth of 1,380 

 feet, the density of the water was less than at 642 feet 



* There is a typographical error in the work, from whence the above 

 is extracted, where it is stated that the specific gravity at the surface is 

 1-2061 instead of 1-026]. 



