Temperature of the Terrestrial Globe. 11 
sily imposes upon the majority of learned men, as they are founded 
upon a great number of experiments, which have no other fault than 
that of being badly comprehended. 
I have already descanted at large upon this subject, in the Bulle- 
tin Universel of M. de Ferussac. But as we nevertheless see men 
distinguished in physical science, still adhering to a system which has 
been once refuted, I have for more than forty years,* thought it would 
be right to offer an exact analysis of the facts upon which the attempts 
to reconstruct it are founded. ‘These facts consist of experiments 
made upon the temperature of the earth, at different depths and up- 
on different points of the continent. I shall therefore examine these 
facts in order to assign to them exactly the value which they hold in 
the problem of the temperature of the terrestrial globe. Afterwards 
I shall produce the experiments made at great depths, and upon dif- 
ferent points of the earth, in the ocean, and in lakes, to compare them 
with the terrestrial experiments. J shall then solve the apparent con- 
tradiction between the marine and terrestrial experiments.. Finally I 
shall consider the hypothesis of central fire as a geological system, in 
order to examine whether it is not in contradiction to the better known 
geognostical facts, and whether it is capable of throwing any light up- 
on the formation of the crust of our globe. This will furnish mate- 
rials for four chapters.” 
Such is the distribution of the great work of M. Parrot, upon a 
subject which merits the attention of natural philosophers, and upon 
which they are still far from being agreed. It is impossible for us to 
follow him in the developement of the first of the four great divisions 
of his memoir, in which he discusses the observations upon which has 
been established the belief of an increasing progression of the terres- 
trial temperature from the surface to the centre, and in which he en- 
deavors to demonstrate that these observations do not present the ac- 
cordance and regularity necessary to the base of a law, more espe- 
cially, he observes, if we consider that the depths to which we have 
penetrated, with the thermometer, have been only to seven hundred 
and two metres, and that the attempt is made to extend the result of 
these observations to the depth of twenty five or thirty leagues, that is 
* Those who would infer from these remarks, that I am unjust towards Buffon, are 
desired to read what I have said of his system in my Discourse upon Physics, tome 
vi, p. 681 and 684. No Frenchman even has ever spoken more honorably of this 
great savan. 
