We cross the Humboldt Mountains by a series of grades shorter than that which conducts us over the Rocky system, but full as difficult in proportion. We descend into a second instalment of Desert on the other side; but the general sterility is now occasionally broken by oases, moist green _canons_, and living springs. A hundred miles west of the Humboldt Pass we come to the mining-settlements of Reese River, gaining a new increment to the business of the road in the transportation of silver to San Francisco, and every conceivable necessary of life to the mines.--Within the last eighteen months eleven hundred dollars in gold have been paid for the carriage by wagon of a single set of amalgamating-apparatus from Virginia City to Reese, a distance of two hundred miles. The price of the commonest necessaries at the Reese-River mines has reached the highest point of the old California markets in '49,--and no attainable means of transport have been adequate to supply the demand. From Reese River to Carson we traverse a broken, rocky, and sterile tract, with occasional fertile patches and a belt along the Carson River susceptible of cultivation. The foot-hills of the Sierra Nevada gradually shut us round, and at Carson we begin penetrating the main system through a series of magnificent galleries between precipices of porphyritic granite, leading nearly northward to the Truckee Pass. The grades we now encounter are as tremendous as any in the Rocky-Mountain system. Just before entering the main pass we come to the junction of a branch-road from Virginia City. The train which stops at the fork to let us go ahead is carrying down several tons of silver "bricks" from the Washoe mines to Kellogg and Hewston's, the great assay and refining firm of San Francisco. The pass takes us across the summit-line of the range, but not out of the environment of its mountains. We penetrate granite fastnesses and descend blood-chilling inclines, span roaring chasms and glide under solemn roofs of lofty mountain-pine, until in the neighborhood of Centralia we begin for the first time to see the agricultural tract of the Golden State.