164 iOSEPH FOURIER. 



sioiis a new proof of the high temperature enjoyed by our country before 

 the last irruptions of the ocean. 



The study of fossil animals is no less fertile in results. I should digress 

 from my subject if I were to examine here how the organization of 

 animals is developed upon the earth; what modifications, or more 

 strictly speaking, what complications it has undergone after each cata- 

 clysm, or if I even stopped to describe one of those ancient epochs 

 during which the earth, the sea, and the atmosphere had for inhabitants 

 cold-blooded reptiles of enormous dimensions; tortoises, with shells three 

 feet in diameter; lizards seventeen meters long; pterodactyles, veritable 

 flying dragons of such strange forms that they might be classed on 

 good grounds either among reptiles, among mammiferous animals, or 

 among birds. The object which I have proposed does not require that 

 I should enter into such details ; a single remark will suffice. 



Among the bones contained in the strata nearest the present surface 

 of the earth are those of the hippopotamus, the rhinoceros, and the 

 elephant. These remains of animals of warm countries are to be found 

 in all latitudes. Travelers have discovered specimens of them even at 

 Melville Island, where the temperature descends, in the present day, 

 50° beneath zero. In Siberia they are found in such abundance as 

 to have become an article of commerce. Finally, upon the rocky 

 shores of the Arctic Ocean, there are to be found not merely fragments 

 of skeletons, but whole elephants still covered with their flesh and skin. 



I should <leceive myself very much, gentlemen, if I were to suppose 

 that each of you had not deduced from these remarkable facts a conclu- 

 sion no less remarkable, to which, indeed, the fossil flora had already 

 habituated us ; namely, that as they have grown older the polar regions 

 of the earth have cooled down to a j)rodigious extent. 



In the explansition of so curious a phenomenon, cosmologists have not 

 taken into account the existence of i)ossible variations of the intensity 

 of the solar heat ; and yet the stars, those distant suns, have not the 

 constant brightness which the common people attribute to them. Nay, 

 some of them have been observed to diminish in a sufficiently short 

 space of time to the hundredth part of their original brightness ; and 

 several have even totally disappeared. They have preferred to attrib- 

 ute everytliing to an internal or primitive heat with which the earth 

 was at some former epoch impregnated, and which is gradually being 

 dissipated in space. 



Upon this hypothesis the inhabitants of the polar regions, although 

 deprived of the sight of the sun for whole months together, must have 

 evidently enjoyed, at very ancient epochs, a temperature equal to that 

 of the tropical regions, wherein exist elephants in the present day. 



It is not, however, as an explanation of the existence of elephants in 

 Siberia that the idea of the intrinsic heat of the globe has entered for 

 the first time into science. Some savants had adopted it before the dis- 

 covery of those fossil animals. Thus, Descaiites was of opinion that 



