SUTRO, Adolph Heinrich Joseph, mining engineer, born in Aix-la-Chapelle, Rhenish Prussia, 29 April, 1830. He was educated in his native place. His father was a cloth-manufacturer, and Adolph learned the details of the business and travelled for the factory, but the elder Sutro died before the son was old enough to continue the business, and the family, consisting of seven sons and four daughters, came to New York in 1850. During the voyage Adolph had learned of the gold fever in California, and, soon after establishing the family in Baltimore, he set out for the Pacific coast. Having studied mineralogy in the best polytechnic schools in Germany, he was much better prepared for mining operations than the majority who at that time were flocking to the gold-fields. He visited Nevada in 1860, and, after a careful inspection of the mining region there, he planned the now famous Sutro tunnel through the heart of the mountain where lay the Comstock lode. Having interested capitalists in the project, he obtained a charter from the Nevada legislature on 4 February, 1865, and the authorization of congress on 25 July, 1866. The mining companies agreed to pay a toll of $2 for each ton of ore, from the time when the tunnel should reach and benefit their mines. The work was begun on 19 October, 1869. It proceeded as rapidly as its character would permit, and before the close of 1871 four vertical shafts were opened along the line of the tunnel, one of which was 552 feet deep. The distance from the mouth of the tunnel to the Savage mine, where, at a depth of 1,650 feet from the surface, it formed the first connection with the Comstock lode, is 20,000 feet. Lateral tunnels connect it with the mines on either side of the main bore. In 1879 the great tunnel was finished, and its projector became a millionaire many times over. Some of the mines at the level of the tunnel were flooded with water to the depth of one hundred feet or more, and had long been abandoned; others were unworkable on account of the heat and noxious gases. The tunnel with its shafts effectually ventilated them, and within a few days they were rid of the accumulated water which had a temperature in some mines of 160 Fahrenheit. Mr. Sutro has devoted a part of his fortune to the collection of a fine library and art gallery in San Francisco. In 1887 he presented that city with a copy of Freddric A. Bartholdi's statue of "Liberty enlightening the World."