M. L. Cordier on the Temperature oj 



that of the resistance which forged iron, subjected to an enor- 

 mous pressure, is capable of opposing to fusion. We might be 

 inclined to reduce the temperature, on considering that Newton''s 

 experiments, confirmed by those of Mr Barlow, have proved that 

 iron, raised to a white heat, loses its magnetic virtue. But, on 

 the other hand, it must not be lost sight of, that an excessive 

 pressure of the metal should probably protract in a great degree 

 the term at which the magnetic virtue is thus destroyed. 



25. Lastly, According to the same hypothesis, there would 

 be reason for making inquiries respecting various extremely 

 slight, secular, and not hitherto perceived, effects, which the 

 different positions, and the irregular form of an internal solid 

 mass, possessed of a peculiar motion, and composed in part of 

 metallic iron, might occasion. Thus, for example, we might 

 be led to doubt the perfect and absolute invariability which has 

 hitherto been attributed to the direction of the plummet in each 

 place ; and this doubt would apply to countries distant from 

 the zones without decHnation, and from the magnetic equator. 



Such are the principal inferences at which we arrive, on intro- 

 ducing the hypothesis of central heat and fluidity, amidst the most 

 important questions of geology. It would be easy to extend these 

 inferences, and, for example, to explain, in an equally satisfactory 

 manner, the formation of the unstratified primordial rocks, that of 

 the transition rocks, of veins, and of the gypseous, sulphureous, 

 saline, calcareous and magnesian strata of the secondary series. 

 The fecundity of applications is remarkable, and adds to the pro- 

 bability of the principle. The case is different with the Neptunian 

 system, which so long prevailed, and which represents the globe 

 as a cold inert mass, solid to the centre, and formed from with- 

 in outwards by aqueous depositions. This system has proved 

 a sterile one, and none of its applications are now able to stand a 

 serious examination. It reduces itself to narrow limits, to the 

 explanations of those superficial strata, formed of consolidated 

 sedimentary matters, of agglomerated debris and organic re- 

 mains, which constitute almost the whole of the excessively 

 thin envelope, named secondary. Had not the authority of 

 the naturalists who brought this system into credit, given a 

 bias in its favour, it is evident that, at its commencement, it 

 would have been made to undergo a very simple trial, from 



