350 M. Amedee Bui-at oti the 



school, by adding numerous important facts drawn from 

 other countries. 



A School of Mines, recently founded in Madrid, has fol- 

 lowed the same principles, and confirmed them by remark- 

 able observations, among which we may mention those of 

 MM. Ezquerra del Bayo, Don Luis de la Escosura, Pellico. 



The miners of Cornwall and Devonshire, who have in some 

 measure established their practical doctrines by their own 

 unaided observations, have come to an almost literal repeti- 

 tion of the German views. These principles, carried by them 

 to the mines of the New World, have thus become universal, 

 and the names of De la Beche, Jackson, Fox, and Henwood, 

 have given them additional authority. 



Let us give a short account of these great principles, which 

 all these observers and practical men have sanctioned by 

 their labours. 



Metalliferous repositories belong to two distinct classes, 

 which are the regular repositories, and the irregular. 



Regular repositories comprehend all the veins which re- 

 sult from fractures posterior to the inclosing formations, and 

 filled after their formation by special gangues and minerals, 

 to which the debris of the roof and walls are added. These 

 repositories are essentially independent of the inclosing for- 

 mations : they abound in transition formations, and have been 

 found in the trias and Jurassic formations, and even in those 

 of the upper chalk ; in like manner, they form furrows in gra- 

 nites, porphyries, and trap rocks. In all these positions, the 

 veins affect characters of allure* conformable to their origin ; 

 they are modified according to the conditions of the fractured 

 rocks, and to the more or less easy cleavages of the forma- 

 tion ; but they preserve, in their mode of progress, the re- 

 gularity and continuity which justify their definition. 



The ii'regular repositories, on the contrary, cannot be 

 bi'ought under any general definition of foi'm and allure. In 

 every locality, they have characteristics altogether special ; 

 but all are geognostically connected, in a gi"eater or less de- 

 gree, with the formations which inclose them. Whether they 



* ^Wio-e signifies the direction, inclination, and widtli, of a mineral repositor)'. 



