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geognostic description of South America, not 

 only on account of the interest of novelty which 

 the study of the formations in the equinoxial 

 regions excites, but also on account of the ho- 

 norable efforts which have recently been made 

 in Europe to verify and extend the working of 

 the mines in the Cordilleras of Columbia, Mex- 

 ico, Chili, and Buenos Ay res. Great capitals 

 have been formed to attain this useful end. In 

 proportion as public confidence has enlarged 

 and consolidated those enterprizes, from which 

 both continents may derive such solid advan- 

 tages, it becomes the duty of those who have 

 acquired a local knowledge of these countries, 

 to publish the materials that are fitted to give a 

 just appreciation of the relative riches and po- 

 sition of the ore-mines in different parts of 

 Spanish America. The success of the associa- 

 tion for the working of mines, and that of the 

 labors undertaken by the order of free govern- 

 ments, is far from depending solely on the im- 

 provement of the machines employed for drain- 

 ing off the waters, and extracting the mineral, 

 on the regular and economical distribution of 

 the subterraneous works, or the ameliorations of 

 preparation, amalgamation, and melting; the 

 success depends also on a thorough knowledge 

 of the different superposed soils. The practice 

 of the art of the miner is closely linked with 

 the progress of geognosy; and it may be proved 



