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List of the mining companies on the Comstock lode, &c.-Continued.

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Deduct 6 feet in dispute between Imperial and Apple & Bates' Cos

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"The 'dead work' (i. e., shafts, wings, tunnels, and excavations not in pay ore) of the Gould & Curry company equals about 12,750 lineal feet, (about 2,4 miles,) with an average cross-sectional area of thirty feet, or about 14,167 cubic yards.

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100

"The companies enumerated above have excavated about 28 miles of tunnels and drifts, and about 53 miles of shafts, wings, and inclines, exclusive of stopes on ore chimneys, which will amount at least to as much more, giving a total of at least 67 miles.

"The longest tunnel penetrating the Comstock lode is the Latrobe, 3,200 feet in length in a straight line, besides various branches, which was commenced in February, 1861, and is still being driven ahead. The above-mentioned companies have forty-four hoisting and pumping engines, which will probably average between thirty and forty horse-power, and give an aggregate of more than 1,500 horse power. The mines of the Comstock employ seventy-six mills for reducing their ores, with an aggregate capacity for crushing 1,800 tons daily, some of which are fourteen miles from the mines, the ore being transported on wagons.

"There is consumed annually by these companies about 22,265 cords of wood, at a cost of not far from sixteen dollars per cord, and a total cost of more than one-third of a million of dollars; and they use about 15,540,120 feet, board

* Evidently an error, and much too large.

measure, of timber and lumber, all of which must be transported long distances on wagons, at a cost of about forty dollars per thousand, or a total cost of nearly two thirds of a million of dollars. Thus, for wood and timber, we have a total annual cost of one million of dollars."

26.—QUARTZ MILLS IN NEVADA.

Surveyor General Martlett, in the report for 1865, gives the following figures of the quartz mills in the State:

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Capacity and machinery of Comstock mills.

The Mining and Scientific Press published the following quartz mills in Virginia City and the vicinity, with the name, the number of tons reduced per month, the number of stamps, and the kind of machinery used in reduction.

Quartz mills in Virginia City and the vicinity, with the name, the number of tons reduced per month, the number of stamps, and the kind of machinery used in reduction.

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12 Wheeler pans, 6 settlers, and 2 concentrators. 30 5-feet plain pans and 2 agitators.

26 plain pans and 1 agitator.

8 Hepburn pans and 4 settlers.

12 Hepburn pans, 6 8-feet settlers, and 1 grinder. 15 Wheeler pans, 5 large settlers, and 2 grinders. 20 2 Hepburn pans, 24 Wheeler flat-bottom pans, 1

settler, and 1 agitator.

8 Varney pans, 5 settlers, and 3 agitators.
6 Hepburn and 4 5-feet flat-bottom pans.
6 pans and 4 settlers.

6 Hepburn pans and 3 large settlers.

600 12 22 6-feet tubs, 3 settlers, prospecting battery, and

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Eclipse

700

15

Crown Point

200

Rhode Island Cr. P't Co.

1,350

25

Union...

400

14

Gold Hill

475

14

Sapphire.

800

16

Petaluma

Imperial

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12 Hepburn pans, 4 furnaces, and 10 barrels; by wet process, 1,000 tons; by dry process, 260 tons. 30 Hepburn pans, 15 settlers, 2 agitators, and 2 grinders.

8 Varney pans and 4 agitators.

15 Wheeler, 4 Knox, and 1 Varney pan, prospecting battery and pan, 6 large settlers, and 10 agitators.

8 Wheeler pans, 4 settlers, and 1 agitator.

1 Blake's breaker, 14 Wheeler and 4 Hepburn pans and 9 settlers.

10 Wheeler pans, 5 settlers, and 2 agitators.

103 Hepburn pans and 7 tubs.

2 Wheeler and 2 Hepburn pans, 5 tubs, and 2 settlers.

10 Varney pans and 3 settlers.

12 Hepburn pans and 6 settlers.

6 Wheeler pans, 2 8-feet settlers, and 2 agitators. 8 Varney pans, 4 settlers, and 3 agitators.

30 20 Wheeler pans, 10 large size Wheeler settlers, 5 agitators, 1 grinder, and 1 Blake's rock breaker. 24 Knox pans and 1 settler.

6 Hepburn pans, 2 settlers and 3 agitators.

750 1, 100

16

24

1,100

500

500

10

500

10

1, 200

24

500

20

800

15

2,400

500

10

500

20

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12 Wheeler pans and 2 large settlers.
16 pans, 8 settlers, and 1 grinder.

16 Varney pans, 6 settlers, and 1 grinder.
1 breaker, 16 Wheeler pans, and 8 settlers.

1 breaker, 12 Wheeler pans, 6 settlers, and 1 agita'r.
1 breaker, 8 Wheeler pans, and 4 settlers.
Working only 36 stamps, (Freiberg process,) 9
furnaces, 24 amalgamating barrels; work 43
men; full capacity of mill, 750 tons.

2 Blake's breakers, 8 furnaces, 20 barrels, 6 Varney and 4 Wheeler and Randall pans.

It appears from this table that there are 331 Knox's pans, 226 Wheeler's pans, 190 Hepburn's pans, 58 Varney's pans, 94 plain pans, 24 Wakelee's pans, 213 settlers, 37 agitators, 12 grinders, 59 barrels, 77 tubs, and two concentrators in use at these mills. Under the head of amalgamating machinery, though not strictly in place, the breakers are mentioned. The list includes 62 mills, 1,226 stamps, 919 pans. The total amount of ore reduced per month is given at 53,787 tons, but the capacity is considerably greater.

27.-THE PAN.

The pan, which is the chief instrument used in the amalgamation of the silver ores of Nevada, is of cast iron, two feet deep, and from two to seven feet in diameter—usually four and a half; to the bottom are fastened dies or movable pieces of iron which form a false bottom, and can be replaced by others when worn out. A shaft rises through the centre of the pan, and to it are fastened shoes or pieces of iron which are to run round over the false bottom and grind the pulp. Many of the pans have chambers at the bottom for steam, which is to keep the pulp åt a heat of about 200°.

28.-THE WHEELER PAN.

The above is a description of the general features of the plain pan, the Wheeler pan, and the Varney pan. The Wheeler pan has curved grooves in the bottom, running from the centre to the rim, to hold the quicksilver. To the sides above the mullers are fastened boards so shaped as to throw the pulp to the centre. But for these boards the pulp would move as fast as the muller, sixty revolutions per minute, and might run over at the sides, and would not be brought into proper contact with the quicksilver at the bottom; whereas by throwing the pulp to the centre the current is broken, the heavy matter sinks to the bottom to be ground, and be mixed with the quicksilver.

29.-THE VARNEY PAN.

The Varney pan has a flat bottom, and is made to grind as well as amalgamate. The speed is greater and the pulp thinner than in the Hepburn. Some vertical pieces of sheet iron, which run from the side of the pan with a curve towards the centre, and in a direction contrary to that in which the muller runs, bring all the pulp successively under the muller. Near the centre there are holes in the muller, into which the heavier matter sinks, and from there it is carried out under the muller, being ground as it passes along. The muller does not reach quite to the side of the pan, so a little space is left there for quicksilver.

30. KNOX'S PAN.

Knox's pan, which is used more than any other, is the simplest of the pans. It is used to amalgamate only, not to grind. Four boards, crossing one another at right angles, are set vertically in the pan, over the mullers so as to keep the surface of the pulp still. If the boards were not there the pulp would run round with the mullers and the ore would not be brought so well in contact with the quicksilver. The mullers run slow, making ten or twenty revolutions per minute.

31.-HEPBURN PAN.

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The "Hepburn pan," as it is commonly known, or, as it is styled by the patentees, the "Hepburn and Peterson pan," which ranks third in the extent of use, has a bottom shaped like an inverted cone, with sides sloping up from the centre at an angle of 45°. The muller sets on this slope, and the pulp, which is mixed with only a little water so as to make a thick paste, runs up under the muller, flows inward over the edge, runs down over its upper surface to the centre, where it again turns to run up under the muller. Thus a constant current is maintained, and every particle of the pulp is successively ground and brought into contact with the quicksilver. The Hepburn pan is made with hard iron mullers and false bottom so as to grind well, and if the ore goes in coarse it comes out fine. The muller makes from forty to sixty revolutions per minute, and a large pan will take half a ton of ore at a charge and amalgamate it thoroughly in three hours.

32.-THE WHEELER AND RANDALL PAN.

It is evident that the iron in Hepburn's pan must be ground as well as the ore, and that the grinding will be the greatest at the sides of the pan and least at the centre. Thus it is that in the flat-bottom pan it is frequently necessary to get new mullers and new false bottoms or dies. To remedy this evil, and to make a pan in which, however much the wear, the muller shall fit close to the bottom, the Wheeler and Randall pan was invented. The bottom of this slopes upwards from the rim; but the slope, instead of being straight, as in the Hepburn, curves inward on the line called the tractory curve. The muller has the same curve, and no matter how much it wears it always fits close to the bottom. The same inventors have another pan made on the same principle, but with the point turned down instead of up. These pans have not come into extensive use, but they are mentioned here to show what experiments have been tried in the mechanical construction of pans.

33.—ESTIMATED YIELD OF VARIOUS MINES.

According to the estimate of Mr. Marlette, the following companies had taken out before the 1st September, 1865, the amounts set opposite their respective names :

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