io 



as an enormous globe revolving on its axis, must gra- 

 dually cool. The whole mass was uniform and began to- 

 solidity upon the surface, when, having become fluid, or 

 even solid, it acquired weight and began to gravitate 

 towards the centre, where again it attained a raised tem- 

 perature. By reason of the continual pressure taking- 

 place in the mass, loss of warmth and continuous solidi- 

 fication went on unceasingly, till the fluid state was 

 reached, i. e. till there arose certain amalgamations which 

 could remain without decomposition in the centre itseltt 

 which is to say when certain metals could firmly amal- 

 gamate with oxygen. Alterwards the process of solidi- 

 fication continued until the earth was converted into a 

 large fluid globe of molten matter surrounded by burning 

 vapours. In such a mass solidifaction proceeded from 

 the surface to tKe centre and round this centre the solid 

 matter concentrated, since here it was more compressed 

 than on the suriace. 



The scientists Hopkins and Fairbairn share this theory,, 

 holding that solidification must begin from the centre 

 since compression raises the melting point, and therefore 

 the cooled strata, sinking trom the surface, did notmelt 

 in the interior of the earth but only thickened and con- 

 densed its general mass. 



Young, in calculating this pressure towards the centre 

 on the earth's surface, 'reckons it capable of reducing^ 

 a granite mass by a whole eighth. Water at a depth 

 from the surface of so geographical miles is twice the 

 surface density, and at a depth of 80 miles would weigh 

 like quicksilver, while steel would shrink to a quarter 

 of its natural bulk, which, according to Herschel's calcu- 

 lation, corresponds to a pressure of 300. 000 atmospheres. 



The French geometrician Poirsson also supports Hunt's 

 theory of solidification from the centre outward. 



Which of these theories of the origin of the earth is 

 actually true heaven only knows, but it would seem that 

 Hunt's nation of the formation of earth from gaseous 

 cloud, cooling from within, is the least probable. For if 



