There shall be appointed, in each judicial district, a meet person, learned in the law, to act as attorney of the United States in such district, who shall be sworn or affirmed to the faithful execution of his office. Act of September 24, 1789, s. 35, 1 Story’s Laws, 67. 2. His duty is to prosecute, in such district, all delinquents, for crimes and offences cognizable under the authority of the United States, and all civil actions in which the United States shall be concerned, except in the supreme court, in the district in which that court shall be holden. Ib. 3. Their salaries vary in different districts. Vide Gordon’s Dig. art. 403. By the Act of March 3, 1815, 2 Story’s L. U. S. 1530, district attorneys are authorized to appoint deputies, in certain cases, to sue in the state courts. See Deputy District Attorney.