119. August 19.-In connection with Major Brooks, aide-de-camp, organized four sap brigades for approaches against Fort Wagner.

120. Between the 18th and 20th of the month, a netting, made of large ropes and floated on barrels, was put across Light-House Inlet by Lieutenant R. F. Butt, Volunteer Engineers, to catch torpedoes or other incendiary bodies intended by the enemy to float down Light-House Inlet and destroy our shipping in the harbor. This contrivance is represented in Plate V, where Fig. 1 is a general elevation; Fig. 2, a plan; Fig. 3, an enlarged view of one panel; Fig. 4 shows the method of securing the floats, which are barrels; a a, are 10-inch mortar shells hung to pieces of rope, to keep the whole steady and vertical.

121. During the night of the 21st of August, another platform, large enough to hold 200 men, to serve as a covering party, was constructed on the marsh, near the junction of the causeways; and to the left and front of this position, out in the marsh, a mock battery of boards and grass was built by Lieutenant N. M. Edwards and Lieutenant Hartmann, to draw the fire of the enemy, in which the device was eminently successful. At this stage of the work, a magazine was made on the hard ground at the easterly and of the causeway, and was intended for supplying the Marsh Battery. Yokes were also made to fit on the necks of men to carry powder, but it was afterward found that boats could be most advantageously used for that purpose.

122. It having been reported at headquarters that some difficulty had occurred during the night at the Marsh Battery, an examination and the following report were made:

123. HEADQUARTERS DEPARTMENT O THE SOUTH,

Engineer Office, Morris Island, S. C., August 22, 1863.

MAJOR: I have the honor to report that, agreeably to orders from the commanding general, I have examined the battery on the marsh, and find that the foundation, parapet, and system of piles, including the gun-deck-in fact, everything, excepting the gun and its parts-are in perfect order.

124. The arrangement of parts that prevented the wooden platform from sliding on the gun-deck having been removed by some person to me unknown, the gun and all its parts down, to the deck have slowdown to the rear some 20 inches.

Very respectfully, your obedient servant,

E. DW. SERRELL,

Colonel, and Assistant Engineer, Department of the South.

Major E. W. SMITH,

Assistant Adjutant-General, Department of the South.

125. The difficulty was remedied by spiking heavy cleats on to the gun-deck, and firing was resumed.

126. On the morning of the 23rd of August, orders were received from the commanding general to put three 30-pounder Parrott rifled guns on Black Island, and to se build the batteries for them and construct platforms that they could fire over the enemy's works on James Island directly upon the city of Charleston. The range, as ascertained by the Coast Survey map, was required to be 8,800 yards.

127. The work was immediately commenced, and a covered way run from the camp near the center of the island to the extreme right, or nearly so, and the batteries were built as represented in Plate VI and Plate VII, wherein Fig. 1, Plate VI, is a general plan of the whole line of batteries, covered way, surgery, and magazine; a is the surgery; b, covered way; c, the magazine; d d, 30-pounder gun batteries; e, 100-pounder gun battery; f, one 30-pounder battery made