THE MARSH BATTERY.

49. On the 16th July, an order was received to see if a position could be found on the marsh, on our left front, where a battery could be constructed.

50. Taking Lieutenant N. M. Edwards, Volunteer Engineers, to assist, I proceeded at once on foot across the swamp to the creek which runs from near the junction of the Plank road to Charleston Harbor. The following is the report made on this reconnaissance:

51. HEADQUARTERS VOLUNTEER ENGINEERS,

Moris Island, July 16, 1863.

MAJOR: I have the honor to report that, agreeably to the orders of the general commanding the department, I made this morning, assisted by Lieutenant N. M. Edwards, Volunteer Engineers, a reconnaissance across the marsh, from the batteries on our left to the creek between this island and Light-House Creek, a distance of about half a mile, bearing, from the southwesterly end of the hard ground, a course by magnetic compass north 40 deg. west, to a point from which the bearing to Fort Sumter is north 12 deg. east, and to the old beacon light south 89 deg. east. At this point there is a spot of hard ground a few inches above or below high-water mark, irregular, from 25 to 30 feet long, and 15 to 18 feet wide, the longer axis being perpendicular to the fire of Fort Sumter, or nearly so. Between this spot and the hard ground on which the batteries are now being built, the marsh may be crossed by infantry at low tide, with some difficulty. About one-third of the distance will bear a man, sinking in 1 or 2 inches, another third, 6 or 8 inches, the other third, somewhat deeper.

52. A battery to be constructed at this point must be entirely made of sand-bags, with platforms grilladed.

53. I think a gun wigging not over 10,000 pounds can be drawn across the marsh on skids framed together to slip on the mud, similar to those used by General Bonaparte for crossing the Alps on the snow.

54. Two thousand three hundred men can carry filled sand-bags enough, in one night, to make the battery and cover the magazine, if they are well organized. Sixty more can carry the platform across and put it down, including the grillage. I t will require about 400 or 450 more men to put the guns in position the next night.

55. The skid should have a bearing surface equal to 90 or 100 square feet.

56. One small creek, about 9 feet wide, will have to be crossed. Two or three logs put over it will be sufficient.

57. Thirty-five additional men can carry the magazine and put it up.

58. The work can be done better in daylight than dark, excepting that it may draw the fire of the enemy.

I have the honor to be, very respectfully, your obedient servant,

EDWARD W. SERRELL,

Colonel of Volunteer Engineers.

Major SMITH,

Assistant Adjutant-General.

59. Subsequently the examinations were pushed down the stream between Light-House Creek and Vincent's Creek to various positions, and, on the morning of the 30th, sounding were made with an iron rod three-quarters of an inch in diameter and 30 feet long.

60. The extreme edges of the swamps on the small creeks are hard, and frequently filled with oysters and oyster shells, but at a few feet from the water they become very soft, and within 10 or 12 feet the mud will not afford foothold for a man.

61. In these marshes, back from the harder edges of the creeks, the mud is from 18 to 23 feet deep, generally about 20 feet deep. It is so soft that the weight of the sounding iron will carry it down 8 or 10 feet, and a man can with one hand push it the remainder of the distance.

62. The bottom is hard sand, or hast that feeling with the point of the sounding iron.