the deepest point of the mine, which according to my measurements* is only 324 metrest above the level of the lake of Zumpango; but the ores which which they extracted did not compensate the expence of the process, and the mine was again abandoned in 1801.

It is surprising that they never thought of substituting to this wretched plan of drawing off the water by bags, proper pump apparatus, put in motion by horse baritels, by hydraulical wheels, or by machines moved by a column of water (colonne d'eau). A level begun at Pachuca, or lower down towards Gazave in the valley of Mexico, would have exhausted the mine of Biscaina at the pit of San Ramon, for a depth of 370 metres. The same object could be attained at less expence, by following the project of M. D'Elhuyar, in placing the mouth of a new level near Omitlan, in the road which leads from Moran, to the place of amalgamation at Regla. This

* I found the absolute height of the lake of Zumpango, 2284 metres (7492 feet. Trans.); the pit of San Ramon 2815 metres (9233 feet. Trans.); now the deepest point of the mine of Biscaina is 307 metres (1006 feet. Trans.) below the upper mouth of the pit. I insert these results here, because in the country it is generally believed, that the works of the Real del Monte have already reached the level of the salt lake of Tezeuco.

last level before reaching 3800 metres* in length, would cut the vein of Biscaina.

The very wise plan which the Count de Regla at present follows is, to leave off the clearing of the old works, and to investigate the mineral repository, in points where it has never yet been worked (in unverfahrenem felde). In studying at Real del Monte, the surface and undulations of the ground, we observe that the vein of Biscaina has furnished for three centuries its greatest riches on a single point, that is to say, in a natural deepening (enfoncement) contained between the shafts of Dolores, Joya, San Cayetano, Santa Teresa, and Gaudalupe. The shaft from which the greatest quantity of silver ores has been extracted, is that of Santa Teresa. To the east and west of this central point, the vein is contracted for a distance of more than 400 metres. It preserves its primitive direction, but becomes destitute of metals, and reduced to an almost imperceptible vein. For a long time it was believed that the vein of Biscaina was insensibly lost in the rock; but they discovered in 1798 very rich metals, at a distance of more than 500 metres, to the east and west of the centre of the old works. They then

* 12,466 feet. Trans.

† 1312 feet. Trans.

‡ 1640 feet. Trans.

sunk the shafts San Ramon and San Pe dro; and they discovered that the vein resumed its old power, and that an immense field was opened to new undertakings. When I visited the mines in the month of May 1803, the San Ramon shaft was only then 30 metres in depth*; and it will be nearly 240 metrest to the bottom of the level of Moran, which is itself still distant 45 metres from the point which corresponds to the intersection of the new shaft, and the roof of the level. In its present state, the mine of the Count de Regla, annually yields more than from 50 to 60,000 marcs of silver.§

The vein of Biscaina contains in the points of the principal mines, milk-quartz, which frequently passes into splintery hornstone, amethyst, carbonate of lime, a little sulphate of barytes, sulphuret of silver mixed with native silver, and sometimes prismatic black silver (sprödglaserz), deep-red silver, galena and iron and copper pyrites. The same silver ores are found near the surface of the ground in a state of decomposition, and mixed with oxide of iron, like the pacos of Peru. Near the San Pedro shaft, the pyrites are some

* 98 feet. Trans.

† 787 feet. Trans.

147 feet. Trans.

§ From 32,815 to 39,378 lb, Troy. Trans.

times richer in silver than the sulphuret of silver.

The mines of Moran, formerly of great celebrity, have been abandoned for 40 years, on account of the abundance of water which they could not draw off. In this district of mines, which is in the vicinity of that of Real del Monte, near the mouth of the great level of Biscaina, there was placed in 1801 a machine à colonne d'eau, of which the cylinder is 26 centimetres in height, and 16 in diameter. This machine the first of the kind ever constructed in America, is much superior to those of the mines of Hungary. It was executed agreeably to the calculations and plans of M. del Rio, professor of mineralogy in Mexico, who has visited the most celebrated mines of Europe, and who possesses at once the most solid and various acquisitions. The merit of the execution is due to M. Lachausée, a Brabant artist of great talents, who has also fitted up for the school of mines of Mexico, a very remarkable collection of models, for the use of students of mechanics and hydrodynamics.t It is to be regretted that this fine machine, in which the regulator of the suckers is put in

* 10.23 by 6.29 inches. Trans.

† See Vol. i. p. 216.

‡ Delius, des mines de Schemnitz, edition of M. Schreiber, § 591.

motion by a particular mechanism, was placed in a situation where there is great difficulty in procuring a sufficiency of water to keep it going. When I was at Moran, the pumps could only work three hours a day. The construction of the machine and the aqueducts cost 80,000 piastres; they did not at first calculate on more than half of the expence, and they ima gined the mass of water to be very consideraable; but the year in which the water was measured being exceedingly rainy, it was believed to be much more abundant than it actually was. It is to be hoped that the new canal which was going on in 1803, and which will be 5000 metres † in length, will remedy this want of water, and that the vein of Moran (hor. 9 inclined 84° to the north-east), will be found as rich at great depths, as the shareholders of the mine suppose. M. del Rio, on my arrival in New Spain, had no other view but that of proving to the Mexican miners the effect of machines of this nature, and the possibility of constructing them in the country. This object has been in part attained; and it will be much more evidently attained when such a machine shall be placed in the mine of Rayas, at Guanaxuato, in that of the

* £10,937 Sterling. Trans.

† 16,404 feet. Trans.