^0 M. L. Cordier oji the Temperature of 



several geological data, not yet interpreted, and of which I 

 shall speak on another occasion, it is probable that the thickness 

 is still smaller. Keeping to the above result, this mean thick- 

 ness would not be equivalent to the sixty-third part of the mean 

 radius of the earth. It would only be the four hundredth part 

 of the developed length of a meridian. 



10. The thickness of the crust of the earth is probably very 

 unequal. This great inequality appears to us to be announced 

 by the inequality of the increase of the subterranean tempera- 

 ture in different countries. The different conducting powers of 

 the strata cannot of themselves account for the phenomenon. 

 Many geological data lead us equally to presume, that the thick- 

 ness of the earth''s crust is very variable. 



11. The heat which the soil of each place continually disen- 

 gages, being the fundamental element of the climate which is 

 established there, and, according to our ideas, the quantities of 

 this disengaged heat not occurring in a constant relation in diffe- 

 rent countries, it is now understood why countries, situated in the 

 same latitude, have, other circumstances being the same, diffe- 

 rent climates, and how Mairan, Lambert, Mayer, and other 

 philosophers, have erred in attempting to represent by formulae 

 the gradation, supposed by them to be regular, which the mean 

 superficial temperature follows from the equator to the poles. 

 There is thus also a new cause added to those which occasion 

 the singular inflexions which the isothermal lines present. 



12. Whatever be the nature of the astronomical forces or 

 events which have formerly disturbed the stability of the conti- 

 nents, and occasioned the general state of dislocation and over- 

 turning which the structure of the earth''s crust exhibits, it is 

 easy to conceive that all the parts of this crust floating, if we 

 may so express ourselves, around a perfectly fluid sphere, and 

 being moreover infinitely subdivided, in consequence of stratifi- 

 cation, and especially from the innumerable contractions which 

 refrigeration has produced in each stratum, may have been dis- 

 located and overturned in the manner in which we see them. 

 These effects are incapable of being explained by the generally 

 received opinion, that the superficial strata were the last conso- 

 lidated, and that the globe is solid to the centre. 



IS. In considering the probable fluidity of the central mass^ 



