The main gallery of the mine is 522 feet in length, the side galleries about 40 feet each. My suggestion is that eight magazines be placed in the lateral galleries, two at each end, say a few feet apart, in branches at right angles to the side galleries, and two more in each of the side galleries similarly placed, situated by pairs equidistant from each other and the ends of the galleries, thus:
Tamping beginning at the termination of the main gallery for, say, 100 feet, leaving all the air space in the side galleries. Run out some five or six fuses and two wires to render the ignition of the charges certain. I propose to put in each of the eight magazines from 1,200 to 1,400 pounds of powder, the magazines to be connected by a through of powder instead of a fuse. I beg to inclose a copy of a statement from General Potter on the subject.
I would suggest that the powder train be parked in a wood near our ammunition train, about a mile in rear of this place. Lieutenant-Colonel Pierce, chief quartermaster, will furnish Captain Strang with a guide to the place.
I beg also to request that General Benham be instructed to send us at once 8,000 sand-bags to be used for tamping and other purpose.
I have the honor to be, general, very respectfully, your obedient servant,
A. E. BURNSIDE,
HEADQUARTERS ARMY OF THE POTOMAC,
July 29, 1864-10.15 a.m.
Commanding Ninth Corps:
I am instructed to say that the major-general commanding submitted to the lieutenant-general commanding the armies your proposition to form the leading columns of assault of the black troops, and that he, as well as the major-general commanding, does not approve the proposition, but directs that those columns be formed of the white troops.
A. A. HUMPHREYS,
Major-General and Chief of Staff.