temperature of the interior of the earth. 1 1 7 



1. These experiments, some more, some less carefully 

 conducted, those of M. Cordier being the least exceptiona- 

 ble, all lead to the conclusion of the temperature increasing 

 in proportion as we descend into the interior of the earth. 

 But it is a prodigious leap, from these experiments in a small 

 way, to the igneous liquidity of the central mass. Tempe- 

 rature increases one degree for each twenty-eight metres; 

 therefore the centre of our globe is in a state of igneous fu- 

 sion ! Intermediate facts seem necessary before we arrive 

 at such an immense conclusion. So far from denying, we 

 readily admit, the igneous fusion of our planet : but Cordier's 

 experiments on the temperature of mines are not of them- 

 selves sufficient to prove it. 



Better proofs exist, in the flattening of our globe at the 

 poles, which the latest experiments seem to fix at 2^55^ * ^ 

 result requiring liquidity. But the most decisive, and in our 

 opinion incontestible proof, is, that glassy obsidian and pum- 

 ice, half fused cinders, and trachytes, pearl stone, &c. are 

 actually ejected from volcanos in a state of absolute fusion 

 in some instances, and high incandescence in others : and 

 that these fused and red hot ejections are not owing to coal 

 set on fire, as Werner supposed, but are situated far below 

 the coal formation, in the granitic crust ; of which, fragments 

 are often ejected. The mass of which these igneous and 

 fused ejections form a part, must itself be in igneous fusion, 

 and incandescent. But this is the central mass below the 

 granite crust. 



2. The subterranean heat will depend in some degree on 

 the depth of the strata of which the crust of the earth con- 

 sists, at the place of observation. Thus, a cavity of twenty- 

 eight metres in the granite, will be nearer the central mass 

 than at a coal mine, or in the surface stratum of the Paris 

 basin, or the London gravel. What allowance ought to be 

 made for these variations in proximity to the central mass, 

 we have no present means of conjecturing beyond the mea- 

 surements collected by Conybeare in England : but it ap- 

 pears to us, that it forms an element not to be neglected in 

 resolving the problem under consideration. Captain Sabine's 

 observations on the variation of the pendulum look the same 

 way. 



3. No allowance is made for the caloric given out at great 

 depths, in proportion as the lower part of the column of at- 

 jnospheric air is condensed by the weight and pressure of 



