SCIENTIFIC NEWS, ^6S 



adit, which opens on one of the creeks of Falmouth harbour, Geologicil so- 

 the entire subterranean length of which is about twenty-four ***'^* 

 miles. 



Copper veins, which, fifty years ago, were considered by the 

 Cornish miners to be peculiar to Schist, have, of late, been found 

 in the parishes of Givenass and Redruth to pass freely from 

 Schist into Granite, and back again to Schist without any de- 

 terioration. The texture and hardness of both rocks is liable 

 to considerable variation, affecting, of course, the profit and 

 progress of the miner often in a very remarkable degree. Two 

 shafts of Fluel Alfred were sunk in Schist, and the cost of one 

 did not exceed 5l. per fathom, while that of the other amounted 

 to 55l. for the same length. 



The metalliferous, or east and west veins, are crossed by 

 others, the direction of which is nearly north and south. — 



These latter are called q,ross courses, and rarely produce 

 copper or tin, or any other metallic substance. The principal 

 practical advantage derived from these veins, especially when 

 consisting of clay, is, that they oppose an effectual obstacle to 

 the passage of water, and therefore the miners do not willingly 

 pierce them without some adequate object in view. The dis- 

 advantage of them is, that they not only interrupt the course of 

 the metalliferous veins, having them from a few inches to several 

 fathoms; but not unfreqiiently totally impoverish them, so that 

 a long and costly search after the heaved part of a vein, often 

 terminates in the mortifying discovery, that it is not worth 

 pursuing, as was most strikingly exemplified in the correspond- 

 ing veins of Huel Jewel and Tol Carn. 



There is another species of vein called aX^ontre or Gaunter, 

 the direction of which is, for the most part, NE. and SW. 

 These are mostly, if not always, metalliferous, and often re- 

 markably rich, of which the mines of Huel Alfred and Her- 

 land have afforded most splendid instances. 



Phosphorescence of Bod'ids. 



Deseignes continues his experiments on the phosphorescence 

 of bodies. It was formerly published, tliat he found, that by 

 violently compressing water in a glass tube^ by a blow, it Jbe- 



cain« 



