Of these shafts, that which attained the greatest vertical depth was the
Combination—the joint shaft of the Chollar, Hale & Norcross, and Savage
Companies. Before work on it was discontinued it had reached the great
depth of 3,250 feet. There is but one deeper vertical shaft in the
world. This is the Adalbert Shaft, in the silver mines of Bohemia, which
is 3,280 feet deep. There is no record of the time when work on this
mine in Bohemia was commenced, though its written history extends back
to 1527. The Combination Shaft was sunk at the rate of three feet a day,
even in rock as hard as flint. The whole shaft is sunk in very hard rock
(andesite), every foot of which had to be blasted. It is thirty feet by
ten feet in size and is divided into four compartments for the
accommodation of the hoisting and pumping apparatus.
The shaft was sunk to the depth of 2,200 feet before more water was
encountered than could be hoisted out in the “skips” with the dirt. Down
to the 2,400 level two Cornish pumps were used, each with columns
fifteen inches in diameter. A drift run west into the vein tapped more
water than the Cornish pumps could handle, when the management
introduced hydraulic pumps. These pumps are run by the pressure of water
from the surface through a pipe running down from the top of the shaft,
whereas the Cornish pumps were run by huge steam engines. The shaft is
connected with the Sutro drain tunnel at the depth of 1,600 feet, and to
that point it was necessary to pump all the water. At the 3,000 level
were placed a pair of hydraulic pumps, the deepest in the world. In
Europe the deepest point at which a hydraulic pump has ever been worked
is 2,700 feet. This is in the Hartz Mountains, in Germany.
When one stood at the 3,000 level and looked up a compartment of the
shaft (five feet by six feet in size) the little spot of daylight seen
at the top appeared to be about four inches square. At this great depth
even the smallest bit of rock falling from the top whistles like a
rifle-ball before reaching the bottom, and, striking a man on the head,
would instantly kill him. Should a man fall that distance little would
remain on which to hold an inquest—his body would be quite “dissipated.”
The Cornish and the hydraulic pumps working together had a daily
capacity of 5,200,000 gallons—a small river! Hydraulic pumps were placed
at the 2,400-foot level, the 2,600 and the 3,000 levels. Some idea of
the great size of these engines and pumps may be formed when it is
stated that the stations excavated for them were eighty-five feet long,
twenty-eight feet wide, and twelve feet high. All this space was so
filled with machinery that there was only room left to move about among
it. Drifts were run to the west to the lode at the 2,400, 2,800 and
3,000-foot levels. On the 3,000 level the distance from the shaft to the
east wall of the vein was found to be only 250 feet. The lode at this
depth (3,000 feet) was found to be of great width and well
mineralized—indeed the Hale & Norcross folks had a good showing of ore.
The Deepest Workings.
Although the Combination Shaft is the deepest vertical opening on the
lode, it is not the point of deepest mining. The deepest workings are in
the mine of the Union Consolidated Company, toward the north end of the
lode. There long drifts were run and much prospecting done at the great
depth of 3,350 feet. This depth was obtained by running a drift from the
bottom of the vertical shaft and then sinking a winze from the drift.
The Yellow Jacket (new) shaft has a vertical depth of 3,050 feet, and
much prospecting was done in the mine at a depth of 3,000 feet; also in
the Belcher and Crown Point. In the Belcher excellent prospects were
being obtained when the company were obliged to discontinue work. By
connecting adjacent shafts by means of drifts and otherwise maintaining
a proper system of ventilation miners experience no difficulty in
working at any depth yet attained on the Comstock Lode.
A Return to the Second Line of Works.
February 13, 1882, a flow of water was tapped on the 2,700 level of the
Exchequer Mine, that flooded not only that mine, but also the Alpha,
Imperial, Yellow Jacket, Kentuck, Crown Point, Belcher, Overman,
Segregated Belcher, and Caledonia. The water rushed to the Yellow Jacket
Shaft, where the pumping was done which drained the advanced workings
(most eastern) of all the mines named. The Yellow Jacket folks pumped
and bailed an average flow of 110 miners inches a day for seven days.
Though they were raising 1,320 gallons every minute the water gained on
them and raised to the level (2,700) on which it was tapped by the
Exchequer. The water had then filled all the drifts, cross-cuts, and
winzes of the whole group of mines from the Bullion south to the
Caledonia. Pumping was still continued, for the purpose of exhausting
the subterranean reservoir in the Exchequer, till March 28, when the
water had been so far reduced that there was a depth of only 950 feet
above the 3,000 level of the Yellow Jacket Shaft. Then, as no combined
arrangement could be made among the several companies interested to
continue the work and drain all the mines, the Yellow Jacket Company
stopped pumping and shut down their works. This stopped all work below
the level of the Sutro drain tunnel, and the works have never since been
started up. Had all the companies “stood in” for a time longer all the
flooded mines would have been thoroughly drained.
The cost of the new works on the advanced line had been so much, and the
expense incurred in hoisting and pumping from such great depths was so
heavy, that stockholders in all the mines along the lode now became
discouraged. They declared that what had happened in the case of the
Gold Hill group of mines was liable to happen in the other deep
workings, and began to clamor for a general return to the works at the
second line of shafts, where it was known that pay ore had been left
behind in the race after depth. When stockholders found that the deep
shafts did not at once cut into pay ore, when they tapped the vein, they
had no patience to wait for much prospecting to be done. They demanded
that paying deposits be sought for at once in the old levels above the
Sutro Tunnel, where there could be no trouble from water. Thus it
happens that along the whole lode all the mining now being done is at
the works situated over the second line of shafts, and above the level
of the Sutro Tunnel. These shafts are by no means shallow, as they range
in depth from 2,000 to 2,900 feet. The return has been fortunate. The
vein being from 400 to 1,000 and even in places 1,400 feet in width
between walls, it was very little explored in the neighborhood of the
works of the second line of shafts. When the bonanzas in sight were
exhausted, the universal cry was: “Get away to the east! Strike the lode
at greater depths! Another 1,000 feet of depth will give us a third
fertile zone—a third line of bonanzas!” Now it is being discovered that
large and rich deposits of ore had been left behind—that they are
scattered in all directions in the great breadth of vein material like
plums in a pudding. Again dividends are the order of the day along the
famous old lode.
The Old First Bonanzas.
Out of the first “bonanzas” great fortunes were taken. The bonanza of
the Ophir, into which the first discoverers of silver—O’Riley and
McLaughlin—accidentally dug, yielded about $20,000,000 before it was
exhausted; the Savage, $16,500,000; Hale & Norcross, $11,000,000;
Chollar and Potosi, $16,000,000; Gould & Curry, $15,500,000; Yellow
Jacket, $16,500,000; Crown Point, $22,000,000; Belcher, $26,000,000;
Overman, $3,250,000; Imperial, $2,750,000, and the Kentuck, Sierra
Nevada, Justice, and many other mines sums running from hundreds of
thousands up into millions. In all, the yield of the mines on the
Comstock Lode from the discovery down to the present time has been
between $350,000,000 and $400,000,000. Of much of the silver and gold at
first taken from the lode, both at Gold Hill and Virginia City, there is
no record; and in many instances since that time much gold and silver
bullion has been obtained from ores, tailings, slimes, and sulphurets
that was never fully accounted for.
The New Departure.
In the new departure, of which a return to the second line of hoisting
works was the leading feature, the two bonanza mines—the California and
the Consolidated Virginia—were consolidated and incorporated as one mine
under the name of the Consolidated California and Virginia. Work was
resumed in the old upper levels and soon small streaks of low-grade ore,
that had formerly been passed by, led to deposits of fair milling ore.
In working these deposits other bodies were found, and finally many new
and valuable ore bodies were developed. A fire which had been
smouldering for about ten years in a section of the old workings was
extinguished by the use of carbonic acid gas, and this gave access to
large deposits of milling ore that had not before been available. This
and the new discoveries soon gave the company large bodies of ore in a
number of places above the Sutro Tunnel level. Again many miners were
employed, and the output of ore became sufficient to keep many stamps in
constant operation.
The total yield of the “Big Bonanza,” in the California and Consolidated
Virginia, was as follows: Consolidated Virginia, $65,116,822.69:
California, $46,858,938.70, making a total of $111,975,761.39. Out of
this the Consolidated Virginia paid dividends amounting to $42,930,000,
and the California a total of $31,320,000 in dividends.
Present Yield of Leading Mines.
Since the consolidation of the two mines, the Consolidated California
and Virginia has yielded $8,001,856.95, and has paid dividends amounting
to $2,440,800, up to and including December, 1888. The total yield of
the great ore deposit known as the “Big Bonanza,” from the time of its
discovery to the end of December, 1888 (under both incorporations), was
$119,977,618.34, and the total amount of dividends to the same date was
$76,690,800. To give an idea of the rate of the present yield of the
mine the following details are furnished: For the quarter that ended
March 31, 1888, the mine produced 39,552 tons of ore, yielding
$921,903.77 in bullion, an average of $23 30 a ton. In April (1888)
there was worked a total of 13,893 tons of ore, yielding bullion to the
value of $418,729.43. The average assay value a ton was $36.83, and the
average yield a ton was $30.13. In May the yield was $411,173.13; in
June, $405,834.08; July, $206,672.26; August, $352,554.97; September,
$267,386.18; October, $339,814.45; November, $220,373.74; and in
December, $260,320.56. The falling off in the month of July and
thereafter throughout the year was due to the dry season in the summer
and a phenomenally dry fall and winter. In January, 1889, there was a
fair milling stage of water in the Carson River the greater part of the
time, and the yield of bullion rose to $267,847.51.
The mine has kept the Morgan and Eureka Mills going to their full
capacity whenever there was sufficient water to run them at all. Owing
to a scarcity of water at the sources of supply in the Sierra Nevada
Mountains, the Virginia and Gold Hill Water Company have for some months
been unable to furnish water for the two California Mills in this city;
to furnish water to the Nevada Mill has been a heavy draft on the
reservoirs. With proper storage reservoirs in the Sierras the mills on
the Carson River might be run the year round. At present eighty per cent
of all the water flows into the “sinks” and is lost.
More mines on the Comstock are at the present time producing paying ore
than ever before in the history of the lode. The following mines are now
ore producing: Consolidated California and Virginia, Gould & Curry,
Occidental, Ophir, Andes, Savage, Hale & Norcross, Chollar, Potosi,
Confidence, Challenge, Yellow Jacket, Belcher, Crown Point, Alta,
Justice, Overman, Baltimore, and Kentuck. Several other companies who
own mines on the lode have quartz that yields promising assays in the
precious metals, and are liable at any time to find paying deposits.
To show the rate at which some of the mines have been paying during the
past year, though handicapped by an unusually dry season and a lack of
milling facilities, I give a few statistics, as follows: During the
quarter that ended March 31, 1888, the Chollar Company milled 1,415 tons
of ore that yielded $21,795.70 in bullion; the Confidence 1,722 tons,
yielding $42,541.72; Hale & Norcross, 7,958 tons, yielding $236,047.32;
Kentuck, 1,027 tons, yielding $13,055.50; Potosi, 3,050 tons, yielding
$56,461.16, and the Yellow Jacket, 16,780 tons, yielding $121,027.82.
For the quarter ending June 30, 1888, the Hale & Norcross yielded 18,075
tons of ore, that produced $451,740 in bullion; the Chollar, 4,750 tons,
yielding $74,507; Confidence, 17,285 tons, yielding $401,293; Yellow
Jacket, 7,080 tons, yielding $55,022.
For the quarter that ended September 30, the Hale & Norcross yielded
6,365 tons of ore, that produced $173,941.80 in bullion; Confidence,
9,207 tons, yielding $176,064.93; Yellow Jacket, 1,370 tons, yielding
$9,932.
For the quarter that ended December 30, 1888, the Chollar milled 2,835
tons that yielded $38,130.81: Challenge, 1,875 tons, yielding
$31,096.16; Confidence, 6,195 tons, yielding $105,970.59; Yellow Jacket,
3,388 tons, yielding $25,856; Savage, 5,292 tons, yielding $66,422.75;
Hale & Norcross, 4,820 tons, yielding $90,015.59, and the Alta, 946
tons, yielding $23,330.
The Consolidated California and Virginia has steadily paid $108,000
monthly in dividends. The Confidence and Hale & Norcross also paid
dividends during 1888 at the rate of from $49,000 to $50,000 a month.
And during the year the pay rolls of the several companies have
aggregated from $250,000 to over $300,000 a month.
During 1888, new bodies of ore were found in the Consolidated California
and Virginia, Hale & Norcross, Confidence, Yellow Jacket, Crown Point,
Gould & Curry, Savage, Chollar, Potosi, Best & Belcher, and some others.
Crown Point and Belcher have made connection with the Sutro drain
tunnel, and are again working below that level. Eventually the leading
companies will get back into the deep workings now deserted.
Vicissitudes of Fortune in Mining.
The vicissitudes of fortune are probably more striking in mining for
silver than in any other kind of mining. In all silver-producing
countries we are told of mines being again and again abandoned because
it was thought their rich “bonanzas” had been exhausted, but they have
again and again been reopened and new and rich bodies of ore discovered.
The Valenciana Mine, on the Veta Macbee (mother vein), of Guanaguato,
Mexico, was reopened in 1760, on a part of the vein where work had been
done in the sixteenth century, and which had afterwards lain as
worthless for 200 years, and in 1768 a bonanza was struck at a depth of
only 240 feet, from which $1,500,000 was extracted annually. And from
1788 to 1810 the annual average was still $1,383,195. At a depth of
1,200 feet the ore was considered too poor for extracting, and the mine
was allowed to fill with water. Afterwards it was again opened and again
paid immensely by working the almost inexhaustible quantities of
low-grade ore.
The Veta Grande, at Zacatecas, which from 1548 to 1832 yielded
$660,000,000, occurs in propalite, as does the Comstock, and has a
similar structure, the vein branching out toward the surface, and
dipping at an angle of forty-five degrees. It is, however, much smaller
than the Comstock. It averages only about thirty-three feet, and eighty
feet is its greatest width. In the upper part the ore was found
concentrated in chimneys, but at depth it was found to be distributed
through nearly the whole width of the vein. At first this low grade
material could not be made to pay, but since it has been profitably
worked and the bullion product has reached a high figure. Scores of such
examples may be found in all silver-producing countries, as chronicled
by Humboldt, Ward, Von Cotta, and others.
Even when no more large deposits of rich ore are to be found on the
Comstock, there are immense and almost inexhaustible areas of low-grade
ore upon which to fall back. In working these small bonanzas are sure to
be encountered—scattered plums in the pudding—which will assist in
sending up the average. New processes for working and concentrating ores
are constantly being discovered, new methods in mining are being
introduced, and new labor-saving machinery is almost daily being
invented. Water-power, steam, compressed air, and electricity are fast
taking the place of muscle. Each year machinery guided by mind is
lessening the work to be done by mere power of muscle. Already the cost
of milling has been greatly reduced, as has the cost of transporting
ores and the cost of wood, lumber, and mining timbers. Present expenses
will shortly be still further reduced.