Charles F. Hartmann, from plans furnished from this office. The work was done by three detachments of volunteer engineers, assisted by fatigue parties of infantry.

Very respectfully, your obedient servant,

EDWARD W. SERRELL,

Colonel Vol. Engineers, and Asst. Eng., Dept. of the South.

Captain BURGER,

Assistant Adjutant-General, Dept. of the South.

NOTE.-The following drawings* represent the booms used to obstruct the water communications between our positions on Morris and Folly Islands and the enemy. For obvious reasons, their positions are not designated at this date. Plates XVIII, XIX, and XX represent in plan, elevation, and cross-section the method of construction. I consider Plate XX the most desirable form to use. No boat or other floating body can pass over it without first submerging the logs and frieze, and, if turned upside down, the obstruction still presents itself. Great attention has been paid to this matter. Many hundred yards of booms like these have been constructed and put in place.

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*XVIII, XIX, and XX.

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17 R R-VOL XXVIII, PT I