438 FIFTYSECOND CONGRESS. Sess. II. Ch. 75. 1893. by piers, solid embankments, or otherwise which will result in unduly gigcglpratigg the highwater current at the site of the bridge shall not owe . ·¤·i¤ ¤>¤=viz¤¢i<>¤- , Sec. 6. That any corporation, company, or persons owning, controlling or operating the bridge built under the authority of this act shall build and maintain at all times, as accessory works to such bridge, such booms, piers, dikes, guard fences, and similar devices as may be necessary to insure at all times a permanent channel for a sufficient distance above and below the bridge site, and for the guiding of rafts, steamboats, and other water craft safely under or through said bridge; and if at any time after the construction of the bridge and its accessory works, the approaches to draw openings, channel spans, or raft passages in said bridge are found to be dangerous or diiiicult of access by river traffic, the Secretary of War may, upon the recommendation of the Chief of Engineers, United States Army, order the corporation, company, or persons owning, controlling, or operating said bridge to construct, under his direction, and to maintain such additional sheer booms, dikes, and other devices as will obviate the diiiiculty mentioned, which additional sheer booms, dikes, and other devices shall be built and maintained at their own expense by said company or persons; and that said company or persons shall maintain, at their own expense, mgimtom. irom sunset to sunrise throughout the season of navigation, such lights and other signals on said bridge as may be required by the Light- House Board for the security of navigation. S¤¤~t¤r,>;;>:‘;¤M<> Sec. 7. That the bridge authorized to be constructed by this act '"”°v°° ‘°shall be located and built under and subject to such regulations tor the security of navigation on said river as the Secretary of War shall prescribe; and to secure that object said corporation shall submit for his examination a design and drawings of the bridge, piers, approaches, and accessory works, and a map of the location, giving, for a space of at least three miles above and one mile below the proposed location, the topography of the banks of said river and the shore lines at high and low water. This map shall be accompanied by others drawn on the scale of one inch to two hundred feet, giving, for a space of onehalf of a mile above the line of the proposed bridge and one-quarter of a mile below, an accurate representation of the bottom of the river, by contour lines five feet apart, determined by accurate soundings, and also showing over the whole width of this part of the river the fbrce and direction of the currents at low water, at high water, and at least one intermediate stage by triangulated observations on suitable floats. The maps shall also show the location of other bridges in the vicinity, and shall give such information as the Secretary 0t.W31' may require for a full and satisfactory understanding of the subject; and the construction of the proposed bridge shall not be commenced until the location and plans thereof are approved by the Secretary of War. ¤1¤¤¤z¤¤·•>¤=· Sec. 8. That any bridge constructed under the authority of this act shall be built under the general supervision of the Secretary of \Var, and no changes or alterations in plans shall be made during the construction of said bridge or after its completion, unless said changes or alterations conform to the provisions of this act and are authorized by the Secretary of War; that such alterations and changes as may be required by the Secretary of War in said bridge so as to preserve tree and convenient navigation shall be made under the direction of the Secretary of WVar at the expense of the company or persons owning, controlling, or operating said bridge. That during original construction or in carrying out any authorized change or repairs of said bridge a navigable channel shall be preserved at the site of the bridge at all times, and the water way of the river shall not be obstructed to a greater extent than is absolutely necessary, and such lights and buoys shall be kept on all coffer dams, piles, and so forth, as may be necessary for the security of navigation.