GEOLOGY. 341 



which they crystallized was the same as their own fusing-point, when heated 

 alone. This fact, however, as well as several important peculiarities in the 

 microscopical structure of the minerals, may be readily explained by sup- 

 posing that the fused rock is simply a liquid that melts at a high temperature, 

 capable of dissolving various minerals, in the same manner as salts are dis- 

 solved in the very fusible substance, water. On cooling to a certain extent, 

 the crystals are deposited from solution, and thus crystallize out at a temper- 

 ature which must be somewhat lower than the fusing-point of the mineral 

 when heated alone, and may be much lower than that. This supposition 

 completely explains why a fusible mineral may act as a nucleus for one that 

 is much less fusible; and it was shown that this peculiarity may be imitated 

 artificially, for when saline aqueous solutions are cooled so as to solidify, 

 crystals of very infusible salts are actually deposited on previously formed 

 crystals of ice." 



GIGANTIC CRYSTALS OF BERYL. 



At a late meeting of the Boston Society of Xatural History, Mr. Francis 

 Alger spoke of the great Beryl formation in the town of Grafton, New Hamp- 

 shire, describing its crystals of gigantic dimensions which had been discov- 

 ered there. One of these crystals, which he had caused to be removed and con- 

 veyed to Boston, weighed nearly two and one-fourth tons, and was five feet in 

 length. Another, the largest single crystal in the world, as far as is known, 

 is nine feet in length, being a six-sided prism, the several faces of which 

 measure respectively in width through the greatest diameter of the crystal, 

 two feet eight inches, two feet, one foot eleven inches, one foot ten inches, 

 one foot six inches, and one foot nine inches thus giving it a circumfer- 

 ence of twelve feet. This crystal yet remains at the locality, but the quartz 

 and feldspar surrounding it have been carefully removed by chisels, so that 

 its position in its native bed can be readily observed. Three weeks labor of 

 two men was expended in this process, as ordinary blasting by gunpowder 

 would have destroyed the crystal. Its weight is probably not less than five 

 tons. 



THE CASPIAN SEA. 



A new map of the Caspian Sea, has recently been published in St. Peters- 

 burg, by Lieutenant Jwatschintson, a naval officer in the Russian service, 

 who was employed by the government to take soundings and examine the 

 shores of this important lake. According to his measurement, the Caspian 

 Sea covers an area of three hundred and fifty-two thousand square versts. 

 Its greatest length is six hundred and fifty geographical miles, and the ex- 

 treme breadth three hundred miles. 



ARTESIAN WELL AT NIONDORF, GERMANY. 



This well has reached a depth of 2247 Parisian feet, having passed through 

 54-11 metres of lias, 206'02 keuper, 142'17 muschelkalk, 311'45 variegated 

 sandstone, IG'24 older slates and grauwacke. The temperature at bottom is 

 27'G3 C., equivalent to an increase of 1 C., in depth for every 31-04 metres. 

 WaJferdin, in Compt. Rend, xxxvi. 2-30. 



29* 



