SILYEE MINING IN COLOEADO. 597 



lead for smelting alone, and that metal is usually supplied by purchasing ga- 

 lena elsewhere, which is then mixed with the material to be treated. Accord- 

 ing to Mr. Watson, superintendent of the mine, the greater part of the product 

 of the mine is low-grade ore, requiring concentration. During the summer of 

 1869 there were 191 tons of mineral smelted at these works. The greater 

 part of this was obtained by concentrating ores that, in the raw state, had an 

 average value of 20 to 30 ounces of silver per ton. According to the average 

 rate of concentration, six tons of raw ore furnish one ton of mineral. This 

 being mixed with the first-class ore, the whole is subjected to the roasting 

 and smelting process. The average assay value of the smelted mineral, during 

 the period referred to, was 200 ounces of fine silver per ton, of which an 

 average of 90 per cent, was obtained by metallurgical treatment. From this 

 it appears that the product of the works, during the summer of 1869, was be- 

 tween $40,000 and $50,000.^ The ore furnishing this yield came partly from 

 the Brown and partly from the U. S. Coin lode. The latter is said to pro- 

 duce much richer ores than the Brown. 



As the hill-side on which the mine is situated is too steep to admit easily 

 of the construction of a wagon-road, the mine has been provided with a sus- 

 pension tramway, the upper end of w^hich is at the mouth of the tunnel and 

 the lower end at the base of the hill. This contrivance consists of two wire 

 ropes, each 1^ inches in diameter, stretched side by side, 6 or 8 feet apart, 

 elevated above the ground and supported at intervals of 200 or 300 feet. 

 The ends of the ropes are securely anchored in the ground. The average 

 inclination of the ropes, from the upper to the lower end of the tramway, is 

 about 20°. Each rope serves as a separate track for the passage of a car, 

 which is attached to a framework of iron ; the latter hanging upon the rope, 

 on which it rests by means of two sheaves or wheels, which, turning freely, 

 permit the movement of the car along the rope. 



The two cars are so arranged that one descends, carrying a load of ore, 

 and, by its weight, draws up the other car, which may also carry a light load 

 of supplies or material for the mine. A small wire rope, a half inch in diam- 

 eter, connects the two cars, passing around a drum at the upper end of the 



^ According to statements made by Mr. Watson, superintendent, and Mr. Cheever, 

 assistant. 



