Beach-Mining.—Beach-mining is the business of washing the sands of the ocean-beach. Between Point Mendocino, in California, and the mouth of the Umpqua River, in Oregon, the beach-sand contains gold, and in some places it is very rich. The beach is narrow, and lies at the foot of a bluff bank of auriferous sand. In times of storm, the waves wash against this bank, undermine it, sweep away the pieces which tumble down, leaving the gold on the beach. The gold is in very fine particles, and it moves with the heavier sand, which alters its position frequently under the influence of the waves and surf. One day, the beach will have six feet depth of sand; the next, there will be nothing save bare rocks. The sand differs greatly in richness at various times: one day, it will be full of golden specks; a few days later, at the same place it will be barren. The sand in the mean time has been moved by the waves, and replaced by other sand.
It is a very difficult matter to know where the sand is rich and where it is not. The companies employed in mining on the beach number about ten men; and there is a foreman who rides out early every morning, following the beach about two miles to the northward and two miles to the southward of the camp, for the purpose of finding where the sand is the best. So changeable is the sand, that a new examination is made every day; and only three or four men are supposed to be good judges of the quality of sand, from its appearance.
When the foreman has selected a place, he orders all the men to it, and they go with twenty pack-mules, which carry the sand in alforjas, or raw hide sacks, to the place of washing, which is up on the bluff, probably a mile or more distant from the spot where the sand is obtained. It happens occasionally that the foreman rides long distances on the beach, and sometimes he will order the sand to be obtained ten miles from the washing-place. The sand must, of course, be very rich, to pay for such transportation, but the beach-sand at times in the sunlight is said to be actually dazzling yellow with gold. The purpose of going upon the bluff to wash it, is to get fresh water for washing; for the sea-water is not so good, nor can it be obtained conveniently. The richest dirt is that the farthest down on the beach, so still weather and low tide are the best times for getting it. When a rich place is discovered low down on the beach, great exertions are made to get as much of the sand as possible before the tide rises. When high tide and storm come together, little can be done. The sand, having been separated from all clay and soluble matter by the action of the sea, is very easily washed, and all collected in a month can be washed in two days in a sluice.
Mining-Ditches.—The placer-mines of California would yield very little gold, were it not for the numerous ditches which supply them with water for washing. The auriferous districts are very dry in summer, and in some places there is not a spring nor a brook within many miles. The artificial ditch supplies the want. The ditches are made by large companies, which sell the water by the "inch." An inch of water is as much as will run out of an orifice an inch square, with the water standing six or seven inches deep in the flume over the orifice. The depth of water over the orifice is called the "head." The orifice is usually two inches high, and as long as necessary to give the amount of water desired. Nobody wants less than ten or twelve inches for mining: a "sluice-head" is about eighteen inches; a "hydraulic-head" is from forty to two hundred inches. The water, however, is not measured accurately. Of course the amount which runs through the orifice will depend to a considerable extent upon the "head," which is usually greater in the morning than at night. At sunrise there may be fifteen inches head, and at sunset only three. The water collects during the night, and is exhausted during the day. The price of water is in no place less than ten cents an inch per day; in some places it is forty cents; the average is about twenty cents.
Many of these ditches are extensive enterprises, and have cost hundreds of thousands of dollars. When they cross ravines and valleys, large flumes—wonders of carpentry—must be built. Some of these are two hundred feet high and a mile long, and so large that a horse and waggon can be driven through them. In all, save length and durability, they are as wonderful as the great Roman aqueducts, whose tall ruins still stand in the Campagna, near the Eternal City. In some cases iron tubes have been used, and although they are very expensive, yet they may pay for themselves, by preventing evaporation, leaking and soaking, which take away much of the water from flumes and ditches.
Prospecting.—"Prospecting" is the search for gold. The instruments used by the prospector for placer-mines are usually the pan, pick and shovel. He should be familiar with the general laws of the distribution of gold, and then try the dirt in the most favorable places. If there is any gold in a district, he can scarcely fail to find specks of it by washing dirt from the bed-rock in the ravines, and in bars. The existence of gold in a district having been established, close observation will suggest to the prospector where he may reasonably expect to find the best diggings. It is usually found that placer-gold is collected in those places where, if he had been familiar with the ancient topography of the country, he should have had reason to suppose that it would be.