“ At the head of the department is a secretary, who is a member of the Cabinet, appointed by the President with the advice and consent of the Senate, and receives an annual salary of $8000. As the President is by the Constitution the commander-in-chief of the navy, the Secretary is generally subject to his direction. It is his duty to execute such orders as the President may give relative to the administration of naval affairs, including the procurement of naval supplies and the construction, armament, equipment, and employment of vessels of war. ”