er which gathers in mines at Virginia City, although the deepest there
so deep as in many in Mexico, is very great, and a tunnel or adit-level
y to secure drainage and ventilation and procure a cheap mode of ex-
e ore and of exploring the lode. Fortunately the lode is situated on
side, and there is an opportunity of draining the lode to a depth of
nd feet by cutting an adit three and three-fifths miles. The expense
eral millions of dollars, but the saving will be far more. Considera-
these led to the formation of the Sutro Tunnel Company, which
franchise from the legislature of the State and a grant of land from
ount of the previously mentioned increase of lead and copper in depth, undergo
ration. Yet they have evidently had at upper levels their concentrated bodies
Such have been extracted at Schemnitz within the time of historical record,
ormer existence at Felsobanya may be inferred from the shape and character of
an works near the out-croppings.

ow return to the Comstock vein, the 'veta madre' of Washoe, and examine
ions as to its future we are justified in drawing from the present condition of the
In the first place, we have mentioned the fact that the ores through all the levels
In their character of true silver ores which they had near the surface. The amount
er, iron, and zinc has never been large in the Comstock ores, and these metals
, at the lowest level, nearly the same relative proportion as formerly. Their
ecially of lead, would be the most unfavorable indication for the future of the
le, as, besides the growing difficulty of metallurgical treatment, the conclusion
tified that lead ores would more and more replace those of silver, and the limits
productiveness would soon be reached. But as it is, no deterioration is to be
en if an impoverishment takes place. It thus approaches in its ore-bearing char-
at mother-veins of Mexico, and is different from those of Hungary. But even
or an impoverishment are by no means so evident as might appear at first sight.
een, it is true, bonanzas near the surface, which surpassed in richness all those
in later times. As such may be mentioned the bonanzas of the Ophir, the Gould
d the western body of ore in Gold Hill. Their richness and the facilities of
on co-operated in making the latter exceedingly profitable. Yet the production
ock veiù did not, at the time when it was solely derived from these surface-bonan-
e figure it attained after the exhaustion of their principal portion. One of the
it then the ore was concentrated within narrow limits, while as the greater depth
the distribution of the ores was much more general, though their standard was
bodies of ore had been discovered, commencing at a depth of from one hundred
hree hundred feet below the surface, such as the continuous sheets of ore in the
of the lode in the Gold Hill mines and the Yellow Jacket, and the similar-con-
in Chollar-Potosi. None of them contain, excepting a few narrow streaks or
3 of equal richness with those of which the surface-bonanzas were composed.
ent so far exceeds that of the latter as to make up, by the increased amount of
on, for the inferior yield. The profits of working are of course greatly dimin
e bodies of ore have continued to the deepest levels reached in the Comstock
ng in width and extent, and also in their yield. The latter did not increase, but
nces, as in the southern part of Gold Hill, decreased with the growing width of
hile in others no material change is perceptible.

bodies of ore made their appearance below the level of three hundred feet.
mportance among them are two bodies discovered at seven hundred feet below
the Hale & Norcross works, one of which is on ground supposed heretofore to

ive.

ng these facts exhibited by the Comstock vein itself, and comparing with them wn about similar argentiferous veins, we believe ourselves to be justified in ollowing conclusions:

the continuity of the ore-bearing character of the Comstock lode in depth must, ng local interruptions, be assumed as a fact of equal certainty with the continuity

elf.

it may positively be assumed that the ores in the Comstock lode will retain r of true silver ores to indefinite depth.

it is highly probable that extensive bodies of ores equal in richness to the sur3 will never occur in depth.

t an increase in size of the bodies of ore in depth is more probable than a deat they are more likely to increase than to remain of the same size as heretofore. t a considerable portion of the ore will, as to its yield, not materially differ at any hat it is at the present lower levels, while, besides, there will be an increasing grade ores. We are led to this supposition by the similarity in character of an utside of the rich surface-bonanzas and the homogeneous nature which almost hem exhibits throughout its entire extent.

Congress, and met with the encouragement of the great companies mi the lode, all of which signed contracts with the company binding thems pay a certain sum for every ton taken from their mines after the compl the tunnel. Although the work has not been commenced, the project prospects, and it occupies an important place in the history of mining in The miners at Virginia City will never be content to abandon that drainage.

40.-COLUMBIA BASIN AND CARIBOO MINES.

The first mines in what is now Idaho Territory were found in the Clearwater river in the spring of 1860, and those of the Salmon riv opened in a few months later. The placers of Boisé were struck in 180 of Owyhee in 1863, and the quartz veins of Owyhee and Alturas beg tract attention in 1864. In castern Oregon the placers of Powder an rivers were discovered in 1861, and those of John Day's river in the year.

None of the Idaho or Oregon placers have proved so rich, so extens durable as those of California, although they have yielded considerable of gold. The deep diggings of Cariboo, 500 miles from Victoria, in part of Fraser valley, were discovered in 1859, and the placers in th bars and creeks at the Big Bend of the Columbia, in the territory Columbia, in 1865. California had to send miners to all these places. The number who went to Idaho was, probably, 20,000; and in 180 5,000 migrated to Montana.

It was also in this year that a rumor became current that rich p been discovered at Barbacoas, in New Granada, and the result was tion and bitter disappointment of about a thousand men, who found reward their trouble.

"6th. That the ore will shift at different levels, from certain portions of the loc as it has done up to the present time. More equality in its distribution may, how pected below the junction of the branches radiating toward the surface, when th probably fill a more uniform and more regular channel. Some mines which hav tofore almost unproductive, as the Central, California, Bullion, and others, ha good chances of becoming metalliferous in depth. But throughout the extent of is most likely that the portion which lies next to the foot-wall will continue unp it did from the surface down to the lowest works, while the entire portion betwe hanging wall must be considered as the probable future source of ore. As rem foregoing pages, it is also probable that repeatedly, in following the lode downwa will be found rising from its main body vertically into the hanging wall and clay of quartz. Many of them will probably be ore-bearing. Such bodies of o sought for, at all the mines, in what is generally supposed to be the eastern cour rience in upper levels would lead to the supposition that such eastern bodies migh ores than the average of the main portion of the vein.

"7th. That the intervention of a barren zone, as is reported by good author at the Veta Madre of Guanajuato at the depth of twelve hundred feet, is not at al met with in the case of the Comstock lode. The argument which we have to a conclusion has some weight from a geological point of view. It is a well kno the enclosing rocks have usually great influence on the quantity and quality o certain metals in mineral veins, and that a rich lode passing into a different quently becomes barren or poor. At the Veta Madre of Guanajuato a sudden d yield of the ore at the depth of twelve hundred feet attends the passage of the l ferent formation, which from thence continues to the lowest depth attained. Να ean be anticipated for the Comstock lode, since the structure of the country see the continuity of the enclosing rocks to an indefinite depth.

"In winding up these considerations, we come to the positive conclusion tha of nearly fifty million dollars, which have been extracted from the Comstock small proportion of the amount of silver waiting future extraction in the virgin p vein, from the lowest level explored down to indefinite depth; but that, from other argentiferous veins, as well as from facts observed on the Comstock lode of the silver through extensive deposits of middle and low grade ores is far 1 than its accumulation in bodies of rich ore."

SECTION 2.

GEOLOGICAL FORMATION, ETC., OF PACIFIC SLOPE. ↓

MR. WILLIAM ASHBURNER, MINING ENGINEER, MEMBER OF THE STATE
GEOLOGICAL SURVEY OF CALIFORNIA, &c.

ing interest of California.-2. Characteristics of the gold-belt-3. Northern
mining districts.-4. Mining in the sierras; mills, expenses, &c.

dance with the request you made me some time since, I beg leave to following report upon the present condition of the gold mining interfornia, so far as it can be ascertained. The absence of all published of a reliable nature, with the exception of those recently issued by cal survey of the State, make it a matter of considerable difficulty to sults which shall have the merit of being perfectly trustworthy, and eans of obtaining them is by personal examination by competent inof the various gold fields throughout the State. Everybody will acthat accurate statistics of the results obtained throughout the extenal regions of the United States, particularly those where the precious found, and published under the official sanction of the government, of the greatest value. If properly compiled they in themselves alone far to remove the great ignorance which prevails in the public mind d to many important facts bearing upon the question of mining, and ple to judge for themselves how far the great majority of those wild which are so frequently made by amateur visitors and newspaper Lents are likely to be true. It is from this class of writers-who, education, are not qualified to weigh and appreciate the value of made to them, generally by interested and enthusiastic personsy all the information which the public now possesses of the gold and es of this country is derived.

versally conceded that the great objection to mining is its uncertainty,
while in some cases the profits are large, the risks are more than pro-
y great, and the cautious capitalist hesitates before embarking upon a
terprise, feeling that a shroud of mystery envelops the whole ques-
hat he may be placing himself blindfolded in the hands of evil and
persons.

neral resources of many of the States have been under scientific inves-
nce 1830; but it was in 1844 that the first district for mining other
man coal and iron was opened up upon the shores of Lake Superior.
wed a wild excitement in mines, which seems to have continued pe-
since that time, upon the discovery of new and valuable mines. In
attention was particularly directed to the silver and gold mines of
ad Colorado. No statements seemed too gross to be made, or too im-
o be believed. Tracts in the midst of the desert covered with sage
I miles distant from any mineral-bearing vein, were located, companies.
-ospectuses issued, and considerable sums of money actually expended
of mines which by no possibility could exist in such places.
ugh survey of the various mining districts which are now attracting
ttention both at home and abroad would confer incalculable benefit upon
y at large, and every means should be employed to bring before the
ormation of such a reliable nature that the capitalist may be guided in
ments, and the field of the prospector for new mines be restricted to

those comparatively limited districts where there is any chance of thei being successful. Money and time uselessly expended in running, pros tunnels, or in sinking shafts that can never be turned to any accou much loss of capital and labor taken from the productive industry of the at large. It was estimated that in 1862-'63 there were some 30,000 in this State and on its immediate borders engaged in prospecting for ver, and copper; and it is a notorious fact that not even one per cen claims discovered by those persons have ever proved remunerative to th invested money in their development. In 1861-'62 the excitement ran copper, induced by the discovery of the Union mine in Calaveras county a few months the Sierra Nevada, from the foot-hills to their summits, w ered with miners fruitlessly occupied in attempting to discover new which could be worked with a profit. A few months of scientific labo in this direction would have shown how utterly futile the efforts of most would prove, and how exceedingly limited in width is the copper-bear of California.

The existence of gold in California was known long before the da monly ascribed for its discovery. In several places along the Coast mountains between Santa Cruz and Los Angeles there were small, ind able "diggings" which were worked by the Mexicans, and some of said to have yielded as much as $6,000 per annum, which, at that per a considerable sum. The interest which is attached to these now is chi torical, and they were generally abandoned as soon as the more exter posits which lie in the Sierra Nevada were made known.

It was on the 19th of January, 1848,* that the first gold east of t Range was discovered on the South Fork of the American river, at a p called Coloma. It was the result of accident, and although attempts w to preserve the fact a secret, the news soon spread far and wide, and by that year it is stated that the number of persons employed on the Ameri and its branches were as many as four thousand, who were obtaini $30,000 to $40,000 a day, and by November it is thought that from for millions of dollars had been already extracted. It was not until a yea quent to this discovery, or in the spring of 1849, that commenced the tensive immigration that the world has ever seen. Adventurers po California from all quarters of the globe: first from Mexico, Chili, a then from the Sandwich Islands, China, and New Holland; lastly United States and Europe. During the six months between the first 1849, and the first of January, 1850, it is estimated that 90,000 persor in California from the east by sea or across the plains, and that one-fiftl perished by disease during the six months following their arrival, such hardships they had endured and the privations to which they were sub

The western slope of the Sierra Nevada was soon covered with who, with their "pans" upon their shoulders, penetrated every ravine "prospecting" the sands and washing the gravel wherever there was finding the precious metal. Mining towns sprang up with almost rapidity, and for several years they presented a scene of busy life. shallow "diggings" soon became exhausted, and in 1851 the yield of higher than it has ever been since, amounting to at least $65,000,000. the last four years California has produced an average of about $3 per annum of gold from the mines situated within her borders. At le per cent. of the total production reaches San Francisco by public co and by some it is considered that even a larger proportion is transpor manner. In order to arrive at the present production, and compare it has been produced in former years, we must take the amount of unc

* History of California by Franklin Tuthill, p. 226.

is known to have arrived here from the various mining districts, and en per cent. for that brought by private hands. At the same time that 3 is far from affording all the accuracy desired, it will give a closer tion to the truth than any other.

g to the San Francisco Mercantile Gazette, which obtains and publarly the amount of coin and bullion received in San Francisco from , we find that the receipts of uncoined treasure from the interior, inthat from Nevada, have been as follows during the last four years: Production of gold from California during the last four years.

production for 1866, based upon the receipts of the first nine months

of the present year.

mines, exclusive, of Nevada bullion

$19,719,900

ompare this production with that of the Australian gold fields during ree years, we find that these latter have produced as follows:

1,627,066 ounces.

1,545,450 ounces. 1,556,088 ounces.

ustralian gold is of remarkable fineness, averaging about, and nsequently, $19 04 an ounce. This would be, in our currency, as

$30,984,336

29,425,368 29,627,916

ineral statistics which are published annually by the colony of Victoria ch valuable information concerning the present situation of the gold nterest in Australia, and from them the above information has been The average earnings of the miners in this colony have been as uring the last three years:

Quartz miners.

Alluvial miners.