Mr D. Ellis cm the Natural History of the Salmon. j?73 



tity with the Wood. The rays of the gills ai*e distinctly 

 seen, and the body of the young animal begins to assume a 

 brownish colour. 

 Kg. 8. A sketch of fig. 5. magnified, to shew more distinctly the cir- 

 culation of the blood. 

 We have no doubt of the general accuracy of these representations of 

 the changes exhibited in the evolution of the ovum of the salmon. But the 

 reader will bear in mind that they are not made by an anatomist, and cannot 

 therefore be expected to present that minuteness of observation, and extent 

 of description, into which one familiar with such subjects would have entered. 



On the Temperature of the Interior of' the Earth. By M. L. 

 CoRDiER, Member of the Royal Academy of Sciences, and 

 Professor of Geology in the Garden of Plants*. 



X HE supposition of a central fire is extremely ancient. It is 

 perhaps coeval with the first dawnings of civilization, and has 

 furnished a basis to some of the fables in which the infancy of 

 the human race has been cradled, traces of it being found in the 

 mythology of almost all nations. It originated from the very 

 imperfect observation of certain natural phenomena, too obvious 

 to have at any time escaped the notice of the vulgar. Confound- 

 ed for ages amidst vague and conjectural notions, which con- 

 stituted nearly all the physics of the ancients and of the middle 

 ages, this hypothesis only began to assume some consistency, af- 

 ter the discovery of the laws of the planetary system. Descartes, 

 Halley, Leibnitz, Mairan,'Buffon especially, and several other phi- 

 losophers of modern times, adopted it, resting chiefly upon consi- 

 derations deduced from the figure of the earth, from certain 

 astronomical phenomena, from the mobility of the subterranean 

 principle which produces magnetic action, from the comparison 

 of the temperatures of the surface with those observed at small 

 depths, and from various experiments on the cooling of incan- 

 descent bodies. 



The inferences derived from these sources not constituting a 

 body of demonstration sufficiently direct to carry conviction with 

 it, many learned men who were contemporary with those men- 

 tioned, remained undecided, while others supported the old opi- 

 nion, which attributed to the earth no other heat than what it 



• Read to the Academy of Sciences 4th June 1827. 



