"It would seem impossible for a large river to collect sediment enough in a sandy, barren soil, to color its waters so deeply as to give it a name among those who first discovered and have since visited its shores. The probability, therefore, is, that this river flows through an alluvial valley of great fertility, which has never been explored. This conjecture is strengthened by the fact that the Indians who inhabit it are hostile, and oppose, as far as they can, all persons who attempt to enter or explore it. This has been their uniform course of conduct respecting all portions of the continent which have been fertile, abounding in game and the spontaneous productions of the earth. "As this valley is situated in the direct route from Santa Fé to California, its thorough exploration becomes a matter of very great importance, especially as it is highly probable that the elevated regions to the north of it, covered with snow during most of the year, will force the line of the great national railway to the Pacific through some portion of it. "The soil I have described, situated west of the Sierra Nevada, and embracing the plain of the Sacramento and San Joaquin, covers an area, as nearly as I can estimate, of between fifty and sixty thousand square miles, and would, under a proper system of cultivation, be capable of supporting a population equal to that of Ohio or New York at the present time." If this account be accurate, the soil of California will yield a rich reward to the agriculturist, and become a strong attraction to permanent settlers, who are willing to trust to the more certain returns for labor spent in tilling it. It is agriculture, undoubtedly, which must give stability to the increase of the country, and, whatever may be the value of the gold mines, furnish California with her substantial wealth. Few cities or towns ever had a permanent prosperity which had not a neighboring country fit for agricultural purposes. The quantity and quality of the present productions of California, other than her mineral wealth, is an important subject for inquiry. Previous to the discovery of the gold, the exportable products consisted almost exclusively of hides and tallow; the inhabitants paying more attention to the raising of horses and cattle than to the cultivation of the soil. The reason is found in the general characteristic of the Californians--indolence. Horses were raised to gratify their passion for riding; and cattle, because they afforded a subsistence at a very small cost of labor. As to what are, and what, by the character of the soil and climate, might be, the products of California, and how the wants of the people are to be supplied, we quote Mr. King's remarks: