Most notable among the ante-bellum pioneers in California was John A. Sutter, whose establishment on the Sacramento had been a centre of the new life. Upon a large grant from the Mexican government he had erected his adobe buildings in the usual semi-fortified style that distinguished the isolated ranch. He was ready for trade, or agriculture, or war if need be, possessing within his own domain equipment for the ordinary simple manufactures and supplies. As his ranch prospered, and as Americans increased in San Francisco and on the Sacramento, the prospects of Sutter steadily improved. In 1847 he made ready to reap an additional share of profit from the boom by building a sawmill on his estate. Among his men there had been for some months a shiftless jack-of-all-trades, James W. Marshall, who had been chiefly carpenter while in Sutter's employ. In the summer of 1847 Marshall was sent out to find a place where timber and water-power should be near enough together to make a profitable mill site. He found his spot on the south bank of the American, which is a tributary of the Sacramento, some forty-five miles northeast of Sacramento. In the autumn of the year Sutter and Marshall came to their agreement by which the former was to furnish all supplies and the latter was to build the mill and operate it on shares. Construction was begun before the year ended, and was substantially completed in January, 1848. Experience showed the amateur constructor that his mill-race was too shallow. To remedy this he started the practice of turning the river into it by night to wash out earth and deepen the channel. Here it was that after one of these flushings, toward the end of January, he picked up glittering flakes which looked to him like gold. With his first find, Marshall hurried off to Sutter, at the ranch. Together they tested the flakes in the apothecary's shop, proving the reality of the discovery before returning to the mill to prospect more fully. For Sutter the discovery was a calamity. None could tell how large the field might be, but he saw clearly that once the news of the find got abroad, the whole population would rush madly to the diggings. His ranch, the mill, and a new mill which was under way, all needed labor. But none would work for hire with free gold to be had for the taking. The discoverers agreed to keep their secret for six weeks, but the news leaked out, carried off all Sutter's hands in a few days, and reached even to San Francisco in the form of rumor before February was over. A new force had appeared to change the balance of the West and to excite the whole United States.