an invention—some one having suggested the idea to him. A. Chabot and M. F. Hoit used them soon after, and greatly improved the arrangement of the riffles and the method of working.t

HYDRAULIC MINING.-The hydraulic system came into use in Nevada county in 1853, and enabled miners to work with profit a vast amount of auriferous ground that would never have paid by the old process of sluicing. About April, 1852, A. Chabot, mining near Nevada City, used a hose of some thirty-five or forty feet in length, through which the water was conducted from the top of the bank to the bottom of his diggings. There was no pipe or nozzle at the end, but still it was found to be a great saving in sluicing off the earth and gravel that had been picked down, and also a convenience in cleaning up the bed-rock. So far as known the hose was not used that season in any other claims, and it does not appear that Chabot discovered the great advantage that would result by directing the stream of water against the bank. This discovery was made by E. E. Matterson a year later. In April, 1853, Matterson and his partners, who were working a claim on American Hill, rigged up a hose, attached a nozzle at the end, and directing it against the bank, as water is thrown upon a building by a fire engine, found that a small stream of water would do the work of a hundred men in excavating earth. Very soon after this the hydraulic was adopted by the miners throughout the county wherever water and a sufficient fall could be procured. Successive improvements have been made in hydraulic mining, until the appliances now in use but little resemble those of 1853; but the principle is the same, and to Matterson is due the credit of the important discovery. The water is usually conducted into the diggings through large iron pipes, at the end of which the hose is attached, and the water having a high fall is combearing gravel was produced by a cause greatly more elevated than the existing river system, or, which is more probable, at a time when the continent was less elevated than at present, and moving in a direction conformable to the course of the valleys of the Sacramento and San Joaquin. We find it impossible to admit the existing river system as a cause adequate to the spreading of such vast masses of rounded materials; the facts plainly point to a much greater volume of water than any now flowing in the valley. The section already given illustrates perfectly the relations of the present river system to the more ancient one whose grand effects are chronicled in the bed rock and its vast superincumbent mass of auriferous gravel. It serves also to illustrate the process now in progress by which the existing river system derived its gold-bearing sands, in great part at least, from the cutting away and secondary distribution of these ancient placers.

"Those who have had the opportunity of visiting other portions of the great gold region of California than that now under consideration, will at once recognize the local character of the details given as perfectly consistent with the general phenomena of the ancient placers as observed elsewhere; while at the same time great differences are found in many of the details. Thus in Calaveras and Tuolumne counties, 80 or 100 miles further south, the volcanic matter capping the auriferous gravel is found in the form of basaltic columns, beneath which occur the same phenomena already described. Here the wood contained in the gravel beds is beautifully agatized, or converted into semi-opal, as is also the case at Nevada City, Placerville, and elsewhere, associated with beautiful impressions of leaves of plants and trees similar in appearance to those now found in this region.

This general description of the deep-lying placers of the Yuba might be greatly extndede from my notes, but enough has probably been said to convey the impression that the phenomena here described are on a grand and comprehensive scale, and referable to a general canse long anterior in date to the existing river system-a cause which has been sufficient to break down and transport the gold-bearing veins of the Sierras, with their associating metamorphic rocks, thus laying up in store for human use deposits of the precious metal in amount on a scale far beyond the notions generally prevailing of the nature of placer deposits."

*It is the opinion of geologists that subsequent to the tertiary period was the time when the main valleys of the continent were excavated by erosion. It was probably in this epoch that the deep-lying auriferous gravel was produced from the degradation of the metamorphic schists and quartz veins of the sierras by the joint action of water and of glaciers.

The sluice is undoubtedly the most essential of any one contrivance for saving gold, and is used in all placer mining operations. It can hardly be called a machine; but is simply a board flume, on the bottom of which are fitted blocks of wood, rounded stones, or riffles, with quicksilver to catch and detain the gold, while the earth and gravel is carried down by the

current.

pressed and forced through an aperture of one and a half to two inches in diameter. The pipes are made of heavy sheet iron, and the hose of stout canvas usually double thickness. Where the pressure is great, the hose are still further strengthened by a net-work of strong cord. In some of the larger mining operations five or six streams of water are kept playing upon the bank, undermining the ground and melting away the hills at an incredible rate. In this manner acres of ground, frequently 100 to 200 feet deep, are washed away in a single season, and the bed-rock left bare. The water shoots from the nozzle with tremendous force, and miners frequently direct the stream against huge boulders to roll them out of their way. The hydraulic is the most effectual method ever yet devised for excavating large quantities of earth, and the process was employed to some extent in 1866, by the Central Pacific Railroad Company in cutting through the deep hills near Dutch Flat.

The American miners, except those engaged in quartz, are chiefly working the deep hill diggings by the hydraulic, the shallow flats and ravines, as a general thing, being abandoned to the Chinese. In most cases, the cost of opening the deep claims is heavy, requiring considerable capital and the nerve to invest it, or the aggregated labor of a number of miners who are content to work, perhaps for years, in the hope of an eventual reward. In too many cases their labor and perseverance has come to naught. The richest deposits are found on the bed-rock in basins or in the channels of ancient streams, and to reach these tunnels have to be run in solid rock, varying in length from a few hundred to several thousand feet in order to drain the ground and get an outlet for sluicing. Wherever practicable, a shaft is first sunk to prospect the ground and ascertain the position of the basin or channel, so that the tunnel in coming in shall be below the auriferous deposit. But this cannot always be done, and expensive tunnels are sometimes found to be too high to work the ground, and a lower one must be run or the claim abandoned. The tunnel serves the double purpose of draining the ground and a sluiceway, and the mining usually commences from a shaft sunk from the surface to the head of the tunnel.

The most important centre of hyraulic mining in this county is at North San Juan, in Bridgeport township, and a brief statement of the operations of some of the companies there will give an idea of the scale on which this branch of mining is conducted. The Eureka Company, whose claims were on San Juan Hill, commenced a tunnel in August, 1855, to reach the inner basin. The tunnel was completed in October, 1860, at a cost of $84,000, in actual assessments, and the cost incurred before a dividend was declared was $142,000. During the existence of the company the average number of men employed daily was 25, and the total yield of the claims $530,000. The claims known as the Deadman Cut, which were worked out in 1859, yielded $156,307, at a cost of $71,433. The claims of McKeeley & Company, on Manzanita Hill, were worked from 1855 to 1864, yielding $368,932, and paying its owners in dividends $126,660. The claims above mentioned have been worked out, but there are other companies still carrying on extensive operations in the vicinity, some of which are deriving a handsome revenue from the profits of working their claims. The tunnel of the American Company is 1,800 feet in length, having been run much of the distance through blasting rock. This company has adopted all the improvements in hydraulic mining. They have a mill with eight stamps for crushing cement, and their sluice boxes extend from Manzanita Hill to the middle Yuba, a distance of nearly a mile, where they have pans for grinding the sand. The company usually employ 25 men, use 500 inches of water, and the claims yield from $10,000 to $15,000 a month. It will require three or four years longer to work out the claims. The tunnel of the Yuba Company is 1,500 feet in length, and was completed last spring after eleven years' labor. This company uses 400 inches of water, and has ground enough to last ten years. The tunnel of the Star Company is 1,400 feet in length, that of the Golden

Gate Company 800 feet, the Wyoming Company 1,000 feet, the Knickerbocker 2,000 feet, the Badger 700 feet, and that of the Gold Bluff Company 1,800 feet. These tunnels have been run for much of the distance through solid rock, which costs from $30 to $50 a foot.

BIRCHVILLE, situated four miles west of North San Juan, has also been a prosperous locality for hydraulic mining. The Irish claims were worked by means of drifting for a number of years, and paid largely. Water was furnished by the Shady creek and Grizzly ditches, but in such limited quantities that little progress was made in hydraulic mining until 1857, when the Middle Yuba Canal Company extended their ditch to Birchville, and furnished water in abundance. In 1859 four bed-rock tunnels were projected, and completed in 1864, at an aggregate cost of $120,000. These tunnels drain the upper portion of the channel; the lower portion will be drained by another tunnel 2,400 feet in length, now in course of construction, by means of which a large extent of valuable mining ground will be worked. The gross yield and net profits of the claims of five of the leading companies at Birchville, for 1866, were as follows, in round numbers:

The years 1865 and 1866 may be regarded as the harvest time for the Birchville miners, as they had previously been at heavy expense in opening their ground, which is now nearly worked out. Many of the owners in the above claims are appropriating a large share of their profits to running the new tunnel. FRENCH CORRAL is situated at the lower terminus of the auriferous gravel range that is found between the Middle and South Yuba rivers. The ravines and flats proved to be rich, and attracted thither a considerable number of miners, at seasons of the year when water could be had to work the claims. The hill diggings were discovered in 1853, and ditches were constructed from Shody creek to bring in water to work them. Tunnels and cuts were run into the hills wherever fall could be obtained, the ditches were enlarged, and profitable mining soon followed. Subsequently deeper tunnels were run, in order to reach the bottom of the deposit, which was found to be from 100 to 200 feet below the surface. The total cost of the various cuts and tunnels of the district cannot be less than a quarter of a million dollars, and the amount of gold taken out must be several millions. A large extent of valuable mining ground remains to be worked. In addition to the hydraulic mines, there is a broad, deep stratum of blue cement gravel which is rich in gold. This will have to be worked by mill process, as is already being successfully done in other parts of the county, and will give work to several mills for years.*

MOORE'S FLAT, situated on the slope of the hill south of the Middle Yuba, in Eureka township, is another important centre of hydraulic mining. Several thousand acres of ground, averaging 100 feet in depth from the surface to the bed-rock, have been sluiced off, giving employment to several hundred miners for the past 15 years. Of late the claims have been bought up by a few large companies, who are carrying on operations upon an extensive scale, and generally with success. At Wolsey's Flat, a mile below Moore's, are some of the deepest diggings in the county, the bank in one place being over 200 feet in height. Orleans flat, two miles above Moore's, was formerly an important mining locality, and at one time had a population of 600 or 800; but the diggings

*For a more detailed account of this district see article on ditches.

being comparatively shallow have been entirely worked out, and the town is now deserted.

At North Bloomfield and Columbia Hill, in Bloomfield township, at Gopher Hill and Scotch Flat, in Nevada township, at Quaker Hill, in Little York, and many other places in the county, hydraulic mining is carried on quite extensively.

The amount of capital invested in hydraulic and placer mining in the county, including the cost of opening the claims, iron pipes, flumes and sluices, and various other implements and improvements, is estimated at $1,500,000. These mines give employment to about 2,000 men including several hundred Chinese, and yield annually not far from $3,500,000-say $1,750 to each man. Three dollars a day is the usual wages paid to miners; but the water bills and other expenses absorb a large portion of the gross product, so that the net yield to the miners, if the whole could be averaged, would be but little in excess of their wages. Of course, some of the claims afford large profits, while others scarcely yield sufficient to pay water bills; but the miners persevere to the extent of their means in hopes of striking better pay.

CEMENT MINING.-In some of the auriferous deposits found in the beds of the ancient lakes and watercourses the gravel is cemented together so compactly that considerable force is required to pulverize it, in order to save the gold by the sluicing process. For this purpose various expedients have been devised by the miners, among which is the erection of stamp mills, similar to those used in crushing quartz, and the business has become of considerable importance in this county. Little York township has taken the lead in this branch of mining. Cement mills have also been erected in Washington, Eureka, Bridgeport, Nevada, and Grass Valley townships, but mostly as adjuncts to hydraulic mining, and the yield from this source, as compared with that from other branches of mining, is small. In Little York, however, it is the leading business.

Blue cement gravel was found in many of the hill claims in Little York township as early as the summer of 1852, and in some of the claims it was so tough that it had to be blasted in order to drift it out. A very small proportion of the gold was saved by merely running it once through the sluices, and the method at first adopted was to pile up the tailings and allow them to remain some months, until the action of the elements had partially decomposed them, and then sluice them again. In this manner each lot of gravel was run through the sluices six or eight times, requiring two or three years for the operation. The Chinamen work the cement in the same manner now, and many are of the opinion that it is the most efficient and economical method; but the process is too slow for American miners.

The first stamp mill for crushing cement was built by the Massassauga Company, near the town of Little York, in the summer of 1857. This mill had no screens, but the cement was thrown into the battery, where the stamps were kept running, and carried off into the sluices by a stream of water. Of course, much of the cement was not pulverized, but the tailings, after running through the sluice, were saved for a year or more and allowed to slack, when they were run through again, and yielded nearly as much gold as on the first run. Another mill was built near Little York in the spring of 1858, which was a considerable improvement on its predecessor, and cement mills have since been erected at You Bet, Red Dog, Hunt's Hill, Gongeye, and other places in the township. The screens now used are nearly as fine as those commonly used in the quartz mills, and it has been fully determined that the finer the cement is crushed the more gold will be saved.

At the present time there are 16 cement mills in Little York township, having in all 136 stamps; two in Washington township with eight stamps, one in Eureka with eight stamps, one in Bridgeport with eight stamps, one in Nevada with 15 stamps, and one in Grass Valley, with eight stamps. These make an aggregate

in the county of 22 mills, with 185 stamps. Some of these mills are kept running steadily, others are in operation only a portion of the time, and a number have been idle for a year or more in consequence of the inability of the owners to open their claims, and other causes. The amount of gravel crushed by a stamp varies from three to eight tons in 24 hours. Sometimes loose gravel is run through the mills to save the gold contained in the quartz pebbles, and which would be lost by ordinary sluicing; but much of the cement is very compact and as difficult to crush as the hardest quartz.

The cement mills are not usually provided with the appliances for amalgamating and saving the gold that are now connected with the quartz mills. Quicksilver is used in the batteries, where the most of the gold is amalgamated, and after leaving the batteries the pulp passes over galvanized copper plates and riffles filled with quicksilver, and whatever gold is not saved by this process is lost. A much-needed improvement is an effectual method of concentrating the sulphurets. These are found in considerable quantities with the cement gravel, and generally contain sufficient gold to yield a good profit when worked by the chlorination process. If machinery, not too expensive, could be devised for separating them from the mass of pulp, it would add largely to the profits of the business.

The working of the cement deposits, like other branches of mining, has had its ups and downs, but on the whole has been progressing, and the business has been increasing in importance since the first mill was erected in 1857. Almost every claim has at times paid largely, and again the receipts would fall below expenses. The gold is unevenly distributed throughout the gravel deposits, being found in great abundance wherever the position of the rock or other circumstances were such as to form riffles, and in other places insufficient to pay the cost of drifting out the gravel. Whether the business is to increase until it becomes of leading importance depends on the character of the deposits that may hereafter be opened in the ancient river channels. A vast amount of placer mining ground yet remains to be opened, and should a considerable proportion of the gravel found therein be cemented so as to require crushing, mills will be erected for the purpose; otherwise it will be worked by the more economical process of sluicing.

The capital invested in cement mining in Nevada county, including the mills, hoisting machinery, cost of opening the claims, &c., is about $400,000; number of men employed, 300; annual yield, $300,000. These figures, given in round numbers, are very nearly correct, as applied to the past three years. There are some outside expenses, which, added to the wages of the miners, will probably somewhat exceed the gross yield. Some of the cement mines have paid largely, while others have proved failures; but the failures have not been so disastrous and universal as the early quartz failures.

EXTENT OF THE PLACER MINES.-The product of the placer mines of Nevada county has neither materially increased nor diminished since 1850, and though they have been worked without interruption for 19 years, the developments of that period have barely been sufficient to give us an idea of their vast extent. The shallow diggings, which were so easily worked, and afforded such large returns to the early miners, are mostly exhausted; but the deep placers, or hill diggings, in the channels of ancient streams, in many places underlying hundreds of feet of alluvial deposits and volcanic material, cannot be exhausted for a long period of time. In fact, for all practical purposes, they may be considered as

inexhaustible.

The long gravel ranges, extending from the high Sierra to the foot hills, cover nearly half the surface area of the country, for the most part are auriferous, and in places are of great depth. Gold in greater or less quantities is found from the surface down, in some places sufficient to pay running expenses; but for their profits the miners mainly rely on striking rich gravel deposits in the chan