NOMOS. 127 



as the heat is communicated, and in this way a 

 comparatively small amount of heat can penetrate to 

 the great body of water below. The land, on the 

 contrary, absorbs the heat with great readiness, and 

 sometimes to a very great extent. Sir John Herschel 

 tells us that he has observed the temperature of the 

 surface- soil in South Africa as high as 159 Fahren- 

 heit, and he gives a quotation from Captain Sturt's 

 exploration in the interior of Australia, which shows 

 the same fact in a still more striking point of view. 

 t( The ground," says Captain Sturt, " was almost a 

 molten surface, and if a match accidentally fell down 

 it immediately ignited." 



And if the land absorbs the heat in this manner, 

 what must be the consequence ? May we not argue 

 that expansion will be one consequence? Such, 

 undoubtedly, is the inference which naturally arises 

 from several familiar facts, and chiefly from some 

 very valuable experiments which were made in 

 America by Colonel Totten, and reported by Lieut. 

 Bartlett, of the United States Engineers.* In 

 building Fort Adams, it was found impossible to 

 join the coping-stones of the walls in such a way 

 that the joints should be perfectly tight in all wea- 

 thers. If the stones fitted tightly together in warm 

 weather, they gaped in cold weather, so as to form 

 cracks through which the rain could readily pene- 

 trate to the wall below ; and with sandstone coping- 

 stones of five feet in length these cracks were wide 

 enough to admit the blade of an ordinary clasp-knife. 



* Prof. Silliman's Journal for 1832, vol. xxii. p. 116. 



