These shafts are, or will be, furnished with machinery of the finest description, capable of working to depths ranging from 1,200 to 2,000 feet. In Southern Gold Hill the original shaft of the Belcher Company has been carried down to a depth of 850 feet.

While many of the originally discovered bonanzas have been worked out, depreciating the value of the mines where they occurred, as in the case of the Ophir and Gould & Curry, the comparatively recent discovery of the SavageNorcross bonanza gives good foundation for believing that they will again become productive. This deposit was not found until the Hale & Norcross Company had been at work for nearly five years, and had attained a depth of 700 feet. Their location covered what was supposed to be a nip of the vein, and having exhausted all other means, as a last resource, the supposed east wall was pierced and a drift run to the eastward from the 700 feet level, with but little encouragement until, at 360 feet east of what had hitherto been considered the east wall, this magnificent discovery was made. The body of ore has been followed up 200 feet, and lying so far from the west wall, will, judging by analogy, continue down for a great depth. This discovery made valuable 800 feet of ground, which up to that time had produced nothing, though lying between the valuable deposits in the Gould & Curry and Chollar-Potosi mines.

Nearly 1,500 feet of ground between the Gould & Curry works and the Ophir mine is to-day in the former condition of this ground, having been prospected only to a depth of about 350 feet, and found to contain nothing, or merely ores of too small a value to pay for extraction. Much other ground which has been examined, chiefly in the neighborhood of the west wall, should be prospected to the east, experience clearly showing that all valuable ore bodies originate on that side of the fissure. The bodies of quartz forming on the west wall are uniformly barren, or of very inferior quality.

The development of the vein has been greatly retarded by various causes. Among these the most prominent have been the fear of causing litigation by prospecting to the eastward and making discoveries which were certain to be claimed by some of the innumerable locations made in early times, and the fact that almost all mining stocks are here owned only temporarily for speculative purposes. In the first respect a happier era is dawning. Repeated litigation has only tended to show conclusively that the many parallel outcrops of quartz, each of which was located by a different company, unite in depth or disappear entirely, and the titles to the principal mines are now nearly free from further dispute. As far as the latter cause is concerned, the trouble will probably continue for many years. To thoroughly understand any arbitrary section of ground a knowledge of the adjoining property is almost indispensable. This is frequently attainable only to a limited extent. It too often happens that the true condition and structure of a mine is concealed, lest the information should affect the schemes of those who are operating in its stocks. A combination of mining superintendents and the establishment of a general office, where maps of the various mines could be consulted by those desiring information, would prove prejudicial to mining-stock speculators, but would tend greatly to check the useless expenditure of money, and materially increase the legitimate profits of our mining enterprises, by enabling superintendents to lay out their work with judgment and greater certainty than is at present the case.

MODE OF MINING ON THE COMSTOCK.-SHAFTS.-Mining on the Comstock is carried on almost exclusively through perpendicular shafts, explorations having penetrated below the deepest adits, which are now used almost exclusively as drains, to avoid the necessity of hoisting the water to the surface. The original shafts were much less substantial than those now in use, being merely lined with planks about three inches thick, the compartments being two or three in number and about four and a half feet square. The principal shafts now in use are fine specimens of mining engineering. The Curtis shaft of the Savage Company

has four compartments, three of them, for hoisting, being five feet square, and the fourth, which is occupied by the hoisting machinery, five feet by six. The Bonner shaft of the Gould & Curry Company and the Chollar-Potosi and Empire-Imperial shafts are similar in their character, while the Hale & Norcross shaft, being intended for the exploration of much less ground, has only three compartments. The mode of construction in all these shafts is similar, cribs of 12-inch timbers being inserted every five feet, supported by vertical posts of the same size. This cribbing is covered on the outside by lagging of three or fourinch planks. Wooden guides are then inserted down each side of the compartments for the purpose of retaining the platform cages, used for ascent from and descent into the mine, in their places. For some years iron guides were much in use, but have now been superseded almost entirely by wood, as less liable to accident. The cost of sinking these shafts varies, of course, with the nature of the ground encountered. The Bonner shaft was put down to the depth of 525 feet, at an average cost of $100 78 per foot, including such a proportion of the total cost of pumping and hoisting as was chargeable to this account. The following table shows the amount expended for each department of the work. It is made up for a depth of 6924 feet, and shows that the last 67 feet of the shaft cost considerably more in proportion than the upper portions, as it raised the average cost per foot to $109 36.

Cost of running machinery, keeping pumps in order, pitmen, &c.....

$22, 324 50

5, 460 05

9,670 67

3,518 00

1,570 50

3,530 00

4,683 75

2,041 50

291 00

1,054 30

1,777 13

19,817 00

75,738 40

TUNNELS AND DRIFTS.-From these shafts drifts are run to the vein, generally about 100 feet apart vertically; but it seldom happens that the levels in any one mine correspond with those in the mines adjoining. This arises from the mines being worked entirely independent of each other. But few of these tunnels will stand without protection. The main working drifts are usually timbered every five feet, the timbers varying from eight to twelve inches square, according to the nature of the ground to be sustained. In many places, even 12-inch timbers cannot resist the immense pressure brought upon them by the slacking and expansion of the material through which the drifts are run, immediately on its exposure to the atmosphere. It is not uncommon to see timbers completely crushed, notwithstanding the utmost precautions, in six months after they have been placed in the mine. Main working drifts, after timbering, are usually about six feet high in the clear, three and a half to four feet wide at the top, and somewhat more in the bottom. Temporary prospecting drifts are much smaller in size, and generally left untimbered, if practicable, till they develop something of value. In each drift is laid a wooden track shod with iron, on which the material extracted from the mine is run out to the shaft in dumping cars, holding from 1,000 to 1,500 pounds. To avoid repeated handling of the ore or waste, the same cars are hoisted on the cage to the surface, and their contents there distributed to the proper places. The following tables will give some idea of the cost of this branch of mining:

STOPING is universally conducted by opening a level below the body of ore to be extracted, and working upward on the vein. On the Comstock, the openings made in mining the ore are so large that a complicated system of timbering is requisite to replace the material extracted. A rectangular system of timbers is usually adopted, the posts being about seven feet in length, 12 inches square, and placed about five feet apart from centre to centre. These are retained in their places by "caps" and "sills," and further to secure the mine each floor, as far as practicable, is filled up with waste material as soon as it is worked out. In early days too little attention was paid to this last precaution, resulting in extensive caves" or giving way of the ground from the superincumbent pressure. If a body of ore is entirely extracted the result is not serious; but should any remain untouched, the cost and difficulty of securing it after a "cave" has occurred in its vicinity is usually greatly increased from the broken and shattered condition of the ground. The quantity of timber used in these stopes is immense, as will be seen by the details of the annual consumption on a future page. Any means which would diminish its price would be a great gain to the entire community.

PROSPECTING for new ore bodies forms a serious item in the cost of mining on the Comstock. When the great and irregular width of the vein, the irregular distribution of the ore bodies, the uncertainty of their occurrence, and our imperfect knowledge of the structure of the vein are taken into consideration, the difficulty of laying out prospecting works to the best advantage becomes apparent. Immense sums of money are spent annually in this kind of work, which must be taken entirely from the pockets of the shareholders when a mine is unproductive. If only moderately productive the entire revenue may be consumed in looking for more valuable bodies of ore; at the same time, the certainty of being richly rewarded for years of waiting if they are found, induces the continuation of work on mines which have not yielded a dollar for years. They are known on the main fissure of the Comstock to be surrounded by good property, and may become valuable at any moment. The Hale and Norcross mine is a good illustration. The following extract is taken from the annual report of the president of the company, for 1866:

Heretofore the entire expense of opening the mine, erecting machinery, &c., had to be borne from money collected by assessments, until they aggregated the sum of $350,000, equal to $875 per foot. For the year just ended the trustees have been enabled to return to the stockholders, in dividends, the sum of $490,000, equal to $1,225 per foot, or, in one year to repay the assessments collected in five years, with the handsome sum of $350 per foot in addition, besides carrying over the large surplus in cash of $133,288 99, equal to a further sum of $333 22 per foot, making altogether the handsome profit, in one year, of $1,558 22 per foot, or 155 per cent. on the par value of the stock.

In this connection the advantages of a community of knowledge and interest among the mining superintendents would be of immense value, the experience of all becoming available by each, thus reducing the cost of explorations by showing in what portion of the different mines deposits of ore are most likely to be found, and thus directing attention more particularly to them. Every dollar spent on an unproductive mine is so much taken out of the aggregate net profits of the mining interest, and every dollar which can be saved would be equal to the same amount distributed in dividends. But because a mine on the Comstock is unproductive to-day, is no reason why it should be abandoned. The only point to be considered is how it may be developed in the most economical manner, and the plan suggested above appears to afford a solution of the difficulty. The inefficient character of the results obtained by many companies working on the Comstock lode, when compared with the money expended, is well known to persons familiar with our mines, and can only be remedied by some such organization.

These engines were almost universally, in early times, attached to friction hoisting gear, but the increase of depth attained has almost banished this mode of operation, the great weight of the rope and car rendering it unsafe. Flat wire ropes have almost entirely superseded the hemp ropes originally employed. For hoisting ore cages are employed in all instances, buckets being used only for sinking in the shafts. These cages are fitted with a variety of appliances to insure safety in case of accident to the ropes or hoisting machinery.

PUMPS. The largest pumps in use are 14 inches in diameter; the greater number, however, range from 10 to 12 inches. The amount of water to contend with varies greatly in different mines, being, as a whole, more abundant in the north end of the lode. The Ophir Mexican pump throws about 300 gallons per minute, and must be run steadily to keep the mine free of water. The Bullion mine, about one mile to the southward, is comparatively dry, and in most cases a few hours' pumping daily is sufficient to rid it of water. Small pumping machinery would generally be sufficient was there not always a risk of tapping bodies of water dammed up by the clay seams in the vein already spoken of. These reservoirs generally yield a large volume when first struck, but rapidly diminish to a small stream. The machinery must be adequate, however, to the duty imposed upon it at such times, otherwise serious detention and damage may be the result.