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DEEP SHAFTS AND DEEP MINING.

A correspondent of the New York Sun, writing from Virginia City, Nevada, describes the progress of the work there on the Combination shaft of the Comstock lode, the deepest vertical shaft in America, and the second deepest in the world.  It is being sunk by the Chollar Potosi, Hale & Norcross, and Savage mining companies; hence its name of the Combination shaft.  This shaft has now reached a perpendicular depth of a little over 3,100 feet.  There is only one deeper vertical shaft in the world—­the Adalbent shaft of the silver-lead mines of Przibram, Bohemia, which at last accounts had reached a depth of 3,280 feet.  The attainment of that depth was made the occasion of a festival, which continued three days, and was still further honored by the striking off of commemorative medals of the value of a florin each.  There is no record of the beginning of work on this mine at Przibram, although its written history goes back to 1527.

Twenty years ago very few mining shafts in the world had reached a depth of 2,000 feet.  The very deepest at that time was in a metalliferous mine in Hanover, which had been carried down 2,900 feet; but this was probably not a single perpendicular shaft.  Two vertical shafts near Gilly, in Belgium, are sunk to the depth of 2,847 feet.  At this point they are connected by a drift, from which an exploring shaft or winze is sunk to a further depth of 666 feet, and from that again was put down a bore hole 49 feet in depth, making the total depth reached 3,562 feet.  As the bore hole did not reach the seam of coal sought for, they returned and resumed operations at the 2,847 level.  In Europe it is thought worthy of particular note that there are vertical shafts of the following depths: 

         &nb
sp;                                           Feet. 
  Eimkert’s shaft of the Luganer Coal Mining
          Company, Saxony 2,653

Sampson shaft of the Oberhartz silver mine,
near St. Andreasberg, Hanover. 2,437

The hoisting shaft of the Rosebridge Colliery,
near Wigan, Lancashire, England. 2,458

Shaft of the coal mines of St. Luke, near
St. Chaumont, France. 2,253

  Amelia shaft, Shemnitz, Hungary. 1,782

  The No. 1 Camphausen shaft, near Fishbach,
          in the department of the Saarbruck
          Collieries, Prussia. 1,650

Now, taking the mines of the Comstock for a distance of over a mile—­from the Utah on the north to the Alto on the south—­there is hardly a mine that is not down over 2,500 feet, and most of the shafts are deeper than those mentioned above; while the Union Consolidated shaft has a vertical depth of 2,900 feet, and the Yellow Jacket a depth of 3,030 feet.  In his closing argument before