leaving two in the exterior battery. On the western face I would arrange platforms for four field guns (1,2,3 and 4). Embrasures' flare, 60 degrees; platforms, 12 feet wide.
At b and c, take down the board revetment of the embrasure, and increase the flare and revet with gabions or Burnettized sandbags.
At 5, 6 and 7, provide platforms for three more field guns. Stop up the postern on this west face.
On the east face of the word I would provide platforms and embrasures for three or four more field guns.
Besides the four 30-pounder Parrotts I propose to put in the work, I would call for nine more guns, viz, seven 20-pounder (or 10-pounder) Parrotts, and two 12-pounder howitzers.
The other platforms to be left vacant. The banquettes should be carefully extended up to the guns, so as to preserve all the infantry fire possible. the platforms of the guns should be 5 feet 6 inches to 6 feet below the crest.
The two boat howitzers now in the exterior battery should be arranged in the western end of that battery, as I suggested, or, perhaps better, in a work immediately west of the fort, so as to flank the slopes and see down to the river.
The counterscarp of Fort Duncan should have a good abatis. At present the enemy can follow unseen the canal tow-path form the north, surround Fort Duncan, and assault it on all sides at once.
The timber on the slopes toward the river, and in the ravine to the north and east, should be felled, a battery and rifle-pits established to sweep the ravine somewhere about the locality we examined for that purpose, and rifle-pits to the north of the fort to see down to the river and into the ravine. The matter requires careful study.
To support Fort Duncan, maintain our communications with it, guard the western slopes of Maryland heights, and protect the batteries on their southern slopes, there ought to be at least two works between Fort Duncan and the foot of Maryland Heights. The points selected by us are well adapted for works. They should be something approaching to square or pentangular redoubts of about 100 yards' side (if square), each having about four field guns and well abatises.
It might, perhaps, be better instead of one work on the right to put two smaller works, with open gorges, on the two points we examined (the stubble field and the wheat field), and sustain them by a stronger work on the higher point in the rear.
It might also be well, should the point on the river near the Sharpsburg road be occupied as a battery, to make that an inclosed work.
With these arrangements carried out, Harper's Ferry ought, with a garrison of 8,000 men, to sustain itself against a large army, and,