206 M. Aratro on the Thermomctrkal State 



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I. At the origin of all things, the Earth was probably incandescent; 

 and even noto contains a large portion of its primitive heat. 



We shall have made a first step towards the demonstration of 

 these two fundamental propositions, if we succeed in discovering 

 whether, at the commencement, the globe were in a fluid or in a 

 solid state. 



If it had been solid when it began its rotatory motion, it would 

 have retained the form it then possessed, in spite of its rotation ; 

 on the other supposition, it would have been the contrary. A 

 fluid mass, in the end, necessarily assumes a figure of equilibrium, 

 corresponding to the various forces to which it is subjected ; or 

 theory demonstrates that such a mass, at first homogeneous, 

 must become flattened in the line of the axis of rotation, and 

 bulge out at the equator ; it gives the difi^erence of the length 

 of the two diameters ; it shews that in the final state of equili- 

 brium, the general figure of the mass is that of an ellipsoid ; it 

 also exhibits the modifications which may result, in physical hy- 

 potheses the most nearly allied, from a want of homogenousness 

 in the liquid strata. Now, all the results of this calculation, 

 whether we regard them in the general, or individually, agree in a 

 most wonderful manner with the numerous measurements of the 

 earth which have been made in either hemisphere. This result 

 cannot, by possibility, be the effect of chance. 



II. The Earthy then, was at one time fluid. 



We must endeavour, then, to discover the cause of this original 

 fluidity. It has just been stated that this cause was flre ; but 

 much is wanting ere unanimity be obtained on the point. The 

 Neptunists will admit nothing but an aqueous fluidity. Accord- 

 ing to them, every terrestrial matter, however distinct in its pro- 

 perties, was originally dissolved in a menstruum ; and the solid 

 frame- work of the globe is formed by deposition or precipitation. 

 The Plutonists, on the other hand, wholly reject the idea of so- 

 lution. According to them, the original fluidity of the consti- 

 tuent principles of the globe, was the result of an exceedingly 

 high temperature ; and the surface has become solid by refrige- 

 ration. 



The two schools, or sects we may rather call them, such has 



