A. BLTTT. 



[No. 1. 



severe pressure, be forced into cavities, and acquires the form 

 of the surroundings. On section of such compressed pieces, it 

 has appeared that the particles or crystals have arranged them- 

 selves with a flowing movement, according to the form of the 

 space into which the piece had been forced. 



Here we must also refer to the interesting investigations of 

 Reusch on compressed conglomerates. Under the severe pressure 

 that has acted on the crust, the pebbles in the conglomerate have 

 been pressed out into lanceolate bodies, and these bodies have, 

 besides, become folded (vide Reasch: Silurfossiler og pressede 

 konglomerater i Bergensskiferne, Univ. Progr. Chria. 1882, p. 15, 

 117). 



On account of the immense pressures existing in the interior 

 of the Earth, we must assume that at a certain depth and on- 

 wards a plastic condition exists. A steady lengthening of the 

 sidereal day would bring the equatorial regions especially to in- 

 crease in weight. As long as the form of the Earth remained 

 unchanged a steadily increasing pressure would act on the in- 

 ternal mass, from lower towards higher latitudes. 



There is, as Darwin accentuates (Nature 2 Sept. 1886, p. 

 422), reason to believe that the Earth, eventually, when the 

 pressure has attained a certain point, will yield. A stream of 

 the plastic mass will be directed to higher latitudes, and continue 

 until the Earth has approached the form corresponding to the 

 length of the sidereal day. When we consider the numerous 

 testimonies of changes having occurred in the solid terrestrial 

 crust, and of the frequent upheavals and lowerings of the dry 

 land in relation to the sea, we must, indeed, agree with DarivM> 

 that this theory is more probable than that of Thomson and Tat- 

 By experiment, Wertheim has (cfr. FocJc: Larobok i fysik eD> 

 Stkhlm. 1861 p. 202, 219) shown that no definite limit of ela- 

 sticity has really been found for any substance, but that they a , 

 even under the action of quite gentle forces, are subjected to 

 small permanent changes, especially if the forces act for a con 

 siderable time. Although we may not find any permanent chaug^ 

 of form under slight strains, that arises from the circumstance 



