42 Geology, as illustrated by Chemistry and Physics. 



We are then compelled to return to the assumption of the 

 pre-existence of melted matter in the interior of the earth, 

 for it is this assumption alone which is supported by fact — 

 the increase of temperature towards the earth's centre — all 

 other hypotheses are destitute of such a basis. 



The celebrated undertaking of the French Government in 

 sending out the expeditions of Bouguer, Condamine Jussieu, 

 &c., to Peru (1735) of Maupertius, Clairaut, Camus, Lem- 

 monier, &c, to the polar regions of Lapland (1736), for the 

 purpose of measuring degrees of latitude, and the subsequent 

 measurements of degrees of longitude and pendulum obser- 

 vations, have demonstrated the flattening of the earth at the 

 poles. By this means, the earlier views of Newton and Huy- 

 gens, based upon the law of universal gravitation, and the 

 centrifugal force of the rotating earth, as well as upon the 

 assumption of a previous fluid state of the earth, were fully 

 confirmed. As a consequence of these investigations, the 

 question arose as to whether this former fluid condition of 

 the earth was one of igneous or aqueous liquidity, whether, 

 therefore, the earth at the time of its creation, was a melted 

 or pasty mass. The state of igneous liquidity presupposes 

 that a greater part of the water of the ocean, rivers, &c, if 

 not the entire mass of water, was diffused throughout the at- 

 mosphere in the form of vapour ; for, upon a melted surface, 

 it could only have retained its liquid form under a most enor- 

 mous pressure. This pressure can only be ascribed to the then 

 existing atmosphere, constituted chiefly of aqueous vapour, 

 and the gradual condensation of this vapour as far as the quan- 

 tity which still exists in the atmosphere to the gradual cooling 

 of the earth's crust ; if, on the contrary, the earth was a pasty 

 mass, then the water which had penetrated the solid mate- 

 rials must have gradually ascended from the interior to the 

 surface ; for in rocks, and especially crystalline rocks, water 

 is either not found at all, or only in extremely small quanti- 

 ties, and as far as observation extends, this water has always 

 been derived from the surface. If, therefore, the different 

 rocks had originated from a pasty mass, the water must have 

 separated by evaporation, somewhat in the same manner as 

 it now separates from moist clay. The increase of tempera- 



