...thrift in the several Comstock mines. The Comstock lode lies on Mount Davidson, in Nevada; though the mines are chiefly owned by San Franciscans. Some of these mines, such as the Ophir and the Mexican , have been worked for twenty years. The silver veins are long; four or five miles in length; but as no one has yet traced them out, their value is an unknown figure. From the stores of Virginia, bu...