1 50 Commentaries on the 



some length, the method of mine-surveying practised inNew 

 Spain, and the simple instruments employed for that purpose ; 

 and he takes occasion to recommend the adoption of the me- 

 thod then practised in Europe, which he illustrates by descrip- 

 tions of the instruments, figures, and diagrams. (Vol. i. p. 327, 

 &c.) The latter method being, in principle, though not in all 

 its details, the same which is now pursued in the Cornish mines, 

 it is unnecessary to refer to it more particularly. 



The various machinery employed in mining and the reduc- 

 tion of the ores, is also described and illustrated by faithful, 

 though rude figures. (Vol. ii. p. 189, &c.) 



In another part of his work, the author discusses the expe- 

 diency of opening the quicksilver mines of New Spain, and the 

 probability of their admitting of being worked with advantage. 

 The trade in quicksilver being monopolized by the crown of 

 Spain, no mines of that metal were allowed to be worked, but 

 those of El Almaden in Old Spain, and Guancavelica in Peru, 

 and hence no progress was ever made in turning to advantage 

 the quicksilver veins of New Spain. But that there are such 

 veins, and that they might be worked to much advantage, is 

 evident from the following passages: 



' In stating above, that we have not met with any account of 

 mines of quicksilver having been worked in the early times after 

 the discovery of the kingdom of New Spain, we are to be under- 

 stood as referring to the sixteenth century, the era of the conquest; 

 but subsequent to that period, many instances may be found. 



'First, some quicksilver mines were discovered in the jurisdiction 

 of Chilapa, at sixty leagues distance from Mexico, to the southward*. 

 Don Gonzalo Suarez de San Martin went over in August, 1676, 

 to explore these mines, with a master smith and master bricklayer, 

 and having set up a shed, a house, a smithy and furnaces, he had 

 a part of the crest of the vein blasted away on the 14th of October, 

 and commenced the works of San Mateo, San Joseph and Santa 

 Catalina, all contiguous. He began three adits at a greater depth ; 

 but the hardness of the ground obliged him to remove half a league 

 farther down, where, finding fair indications of success, he drove 

 the work of la Concepcion. Here also he found very good ore, in 

 a matrix of white spar, and drove a work, which he called los 

 Reyes. He then drove an adit in a cross direction, and, at the 

 distance of 47 varas, cut a vein of considerable size. Several 

 assays were made of the ores from these works, both in the large 

 and small way. Those from San Mateo yielded, by the minute 

 assay, 12 ounces of quicksilver per quintal, those from Concepcion 

 25 ounces, those from the cross-cut 26 ounces. 



* Villa Senor, Theatro Americano, torn, i., page 178. 



