INDEX OF PLATES.

PLATE I.-The bridge for crossing Light-House Inlet, made at Hilton Head, after the model at the engineer camp. Fig. 1 is an elevation; Fig. 2, a plan; Fig. 3, a cross-section; Fig. 4, method of lashing the truss; Fig. 5 the arrangement for holding the floor planks; Fig. 6, shoe to keep the truss from sinking too deeply into the mud.

PLATE II.-The method of sawing off piles under water. Fig. 1, a general view; Fig. 2, a side elevation, the saw hung on the pile; Fig. 3, disposition of the piles to be cut, and the machinery to do it with in plan; a, menthod of hanging the saw on the piles; c, saw secured to the saw-frame.

PLATE III.-Plan of the first parallel, as turned over to Lieutenant Suter, 14th of July.

PLATE VI.-The Marsh Battery. Fig. 1, a cross-section; Fig. 2, general plan; Fig. 3, the foundation of the battery and road; Fig. 4, the experiments for testing the staining strength of the marsh; figs. 5 and 6, the roadway leading over the marsh to the battery.

PLATE V.-The torpedo obstruction, or "Devil Catcher," at Light- House Inlet. Fig. 1, general elevation; Fig. 2, plan; Fig. 3, a panel of the surgery; Fig. 3, longitudinal section of the same.

PLATE VI.-The right batteries on Black Island. Fig. 1, general plan of surgery, four batteries, and a magazine; Fig. 2, cross-section of the surgery; Fig. 3, longitudinal section of the same.

PLATE VII.-The batteries on Black Island, on an enlarged scale. Fig. 1, plan of four batteries: Fig. 2, longitudinal section of the 100-pounder rifle-gun battery; Fig. 3, longitudinal section of the 30-pounder rifle-gun batteries, the guns on siege carriages; Fig. 4, cross- section of the 30-pounder platform; Fig. 5, cross- section of the 100-pounder gun platform, showing the pit; Fig. 6, plan of the magazine on the right of the covered way.

PLATE VIII.-The pier at the north end of Folly Island, constructed during the siege. Fig. 1, an elevation; Fig. 2, a plan. Both of these figures show the scow which was permanently moored at the end of the pier, which raised and lowered with the tide.

PLATE IX.-Shows the temporary pier built at the south and of Morris Island during the siege, plan elevation, and cross-sections.

PLATE X.-The first parallel, as finally completed.

PLATE XI.-The method of putting in the piles in the Marsh Battery. Fig. 1, first arrangement adopted; Fig. 2, plan finally used.

PLATE XII.-The pier at Pawnee Landing, constructed during the siege. Fig. 1, general elevation; Fig. 2, a plan.

PLATE XIII.-The 100-pounder and 30-pounder gun carriages made for experimental purposes. Fig. 1, general plan; Fig. 2, side elevation; Fig. 3, an and view of the 100-pounder gun carriage; Fig. 4, plan of the 30-pounder carriage and chassis; Fig. 5, side elevation of the same; Fig. 6, and elevation of the same. These carriages were for guns to fire at any angle from zero to 10 deg. elevation.

PLATE XIV.-The 100 pounder gun carriage used at Black Island for firing at an elevation of 37 deg. Fig. 1, general plan; Fig. 2, side elevation; Fig. 3, and view.

PLATE XV.-The permanent wharf at the south and of Moris Island, completed at the close of the siege. Fig. 1, side elevation; Fig. 2, general plan.