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 and, 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:

MAP

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 trough of powder instead of a fuse. I bet 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 Peirce, 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 purposes.

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

A. E. BURNSIDE,

Major-General, Commanding.

[Inclosure.]

HEADQUARTERS SECOND DIVISION, NINTH ARMY CORPS, Before Petersburg, Va., July 26, 1864.

Lieutenant Colonel LEWIS RICHMOND,

Assistant Adjutant-General, Ninth Army Corps:

COLONEL: I desire to call the attention again of the general commanding to the fact that the mining operations on my front are entirely completed, and that with the exception of putting in the charges (which it is not desirable to do until they are wanted for use) the mine has been ready to explode since the 18th instant. The mine is composed of a main drift 5 feet by 4 feet 6 inches, running a length of 550 feet, with lateral galleries amounting to about 80 feet. It is carried under one of the enemy's batteries, and the enemy can be heard at work within the battery and also below the surface. The delay in springing the mine increases continually the probability of its being detected and defeated, and its immediate proximity to the enemy's work renders it highly