Continuitij of Metalliferous Repositories hi Depth. 361 



The repositories of Santiago are repositories of contact, 

 lying under highly-developed amphibolites, which exhibit all 

 the characters of the Dillenburg greenstones, and which ap- 

 pear to follow the seams of stratification in the upheaved 

 slates. One of them, the Isabelita, presents the section of a 

 semicircle, and, according to the expression of the miners, 

 sinks like a nail into the interior of the ground. This repo- 

 sitory has been already followed for upwards of 200 metres, 

 with varied success, no doubt, but with great confidence on 

 the part of the miners in the principle of continuity. 



Thus, the operation of mining is pursued in all countries 

 of the globe, in regular as well as irregular repositories, in 

 virtue of this great principle of continuity in depth, a prin- 

 ciple established by geological theories. 



The denial of this theory would be the annihilation of the 

 engineer's art, and of the production of metals. 



If some anomalies exist ; if, for example, the irregular re- 

 positories of Sierra de Gador have occasioned some unprofit- 

 able works ; if the veins of Paullaouen and Huelgoat shew 

 some symptoms of impoverishment, we would invite to more 

 extensive means of research. To such as allege that the ap- 

 plication of the theories of science may lead to deception, we 

 would reply that mining is, and will always be, a hazardous 

 branch of industry ; that deception is possible, considering 

 the slowness and difftculties of the works, but that the re- 

 jection of theories must necessarily lead to inefficiency and 

 ruin. One exception, even were it established, would not 

 overthrow the great principles of the art ; and we think that 

 we express the opinion of all practical men, when we main- 

 tain those principles which were laid down by the Academy 

 of Freiberg, developed and modified by seventy years' ob- 

 servation in all parts of the world. — {Annales des Mines, 

 Quatrieme Serie, tome xi., p. 27.) 



