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in an alarming proportion, when the works have reached a perpendicular depth of 500 metres*. The piercing and walling of the three old draught-pits cost the count de Valenciana nearly six millions of francs, viz.
Piastres The square pit of San Antonio or tiro viejo, 227 metres of perpendicular depth, and four baritels a chevaux 396,000
The square pit of Santo Christo de Burgos 150 metres in depth and two baritels a chevaux 95,000
The hexagonal pit of Nuestra Senora de Guadalupe (tiro nuevo) 345 metres in perpendicular depth and six baritels a chevaux 700,000
Expence of the three pits. 1,191,000
Within these twelve years they have begun to dig in the solid rock, in the roof of the vein a new draught-pit (tiro general) which will have the enormous perpendicular depth of 514 metres f, terminating at the actual
* 1640 feet. Trans,
I reduce the vara* mexicaiuu on the principle that a van h equal to 0" 889 or a toise = 2. 332 vara* mexicmat bottom of the mine or at the planes of San Bernardo. This pit which will be in the centre of the works, will considerably diminish the number of the 080 miners (tenateros) employed as beasts of burden to carry the minerals to the upper places of assemblage. The tiro general which will cost more than a million of piastres * is octagonal and contains 26-". 8 of circumference f. Its walling is most beautiful. It is believed that they will reach the vein in 1815, although in the month of September 1803 the depth was not yet more than 184 metres J. The piercing of this pit is one of the greatest and boldest undertakings to be found in the history of mines. It may be questioned, however, whether for the sake of diminishing the expences of carriage and draught, it was expedient to recur to a remedy which is at once slow, expensive, and uncertain.
(See Vol. ii. p. 165). In that country they consider the mines of Valenciana the deepest ever dug by man. At the period when I measured the planes of San Bernardo, the mine of Bcrchert Gluck, at Freiberg in Saxony had reached 447 metres of perpendicular depth (1465 feet Trans.) It is believed that in the sixteenth century the works of the Saxon mines on the vein Alter Thurmhqf went as far as545 feet in depth (1787 feet Trans.). Author.
* .£218,767 Sterling.
•J- 87 feet. Trans.
$603 feet. Trans*
The. expences of working the mine of Valenciana have been on an average annually:
From 1787 to 1791 .... 410,000* From 179* to 1802 .... 890,000 f Although the expences are doubled, the profits of the share-holders have remained nearly the same. The following table contains an exact stateJ of the mine for the last nine years.
* £89,694 Sterling. Trans. + £194,708 Sterling.
% Estado que manifiesta el valor de los frutos que ha producido la mina de Valenciana, costa de sus memorias y liquido producto, a favor de sus dueños; lo presento Don Joseph Antonio del Maso al Excellentissimo Señor Virey de Nueva España Don Joseph de Icturigarray, el 2 de Julio 1803. (M. S)
The result of this table is, that the net profit of the share-holders, has been latterly at an average of 640,000 piastres per annum.* In 1802 circumstances were extremely unfavourable. The greater part of the minerals were very poor, and their extraction attended with great expence; and besides this, the produce was sold at very low prices, because the want of mercury impeded the amalgamation, and all the mines were incumbered with minerals. The year 1803 promised greater advantages to the proprietors, and they reckoned on a nett profit of more than half a million of piastresf. I saw them sell weekly at Valenciana, silver minerals to the amount of more than 27,000 piastres: The expences amounted to 17,000. At Rayas, the profit of the proprietor was greater, though the produce was less; for this mine furnished more than 15,000 piastres of minerals weekly, while the expence of working only amounted to 4000 piastres. This was the effect of the richness of the minerals, their concentration in the vein, the inconsiderable depth of the mine, and consequently a less expensive draught.
* Above 3,560,000 livres ttfumoia (£140,011 sterling. Trans.) The profit distributed annually among the share-- holders of the district of Freiberg, only amounts to 250,000 livres (*10,4t7 Sterling. Trw.)
f £\05,383 Starling. Tr<»*.