hollows of these beds. AN these methods, properly classed as placer mining, since they work only upon detrital material, have kept up the proportion of gold produced from placers in spite df the rapid exhaustion of the richer concentrations in the lower parts of the stream beds. In 1880, according to census returns, about half of the total gold product .of-the State, which was over seventeen millions of dollars, was derived from placer mines and half from deep mines or original deposits. Later returns do not segregate the product of placer from that of deep mines, but it is safe to assume that the decrease in the gold product during the decade to an average of $12,00i>,000 to $13,000,000 has been largely due to a decrease in hydraulic mining. The farmers had long been complaining of the damage to their arable land resulting from the sands and gravel spread out over them by hydraulic mining, and, as a result of litigation in the early part of the decade, a law was passed entirely prohibiting this form of mining on navigable streams. As a result of this the greater part of the hydraulic mining in the State was stopped, and drift mining, on account of its expense, could not adequately till its place. Costly ditches and hydraulic plants were thereby rendered practically valueless and capital was discouraged from investing in this form of mining, which necessarily involves a very large preliminary expenditure of money before any returns can be expected. In 1892 Congress passed a law providing for the appointment of a commission under whose supervision impounding dams and other means of taking care of the debris might be constructed, which it was expected would result in the resumption of work by a considerable portion of existing hydraulic mines. The statistics of production have not yet shown any beneficial result from this action, which, however, would necessarily be slow on account of the well-known timidity of capital in regard to mining enterprises, especially where any permanent effects of legislation must be depended upon. It may reasonably be looked for in time, however, Avhen confidence iu the efficiency of this measure is created, and especially as a result of the fall in the price of silver, which will naturally direct investments into gold rather than silver mining. Deep or vein mining has apparently been fairly permanent in its production. Where one mine runs out of good ore another runs into it. The increase in expense as the mine grows deeper is more or less offset in reduction in cost of treatment, as mechanical and chemical processes of concentration result in the extraction of an increasing percentage of the gold contained, especially in sulphuret ores.
In those portions of the gold belt beyond the immediate slopes of the Sierra Nevada, both north and south, topographical conditions have not been, as a rule, so favorable to the formation of large areas of placer ground. This incentive to the rapid development of a gold region being wanting, the progress of gold mining has necessarily been slow, although it is known that valuable gold ores exist in the rocks. A commencement has been made, however, and when existing mines have