the siege works to go on and in the course of three or four days shall commence the unloading of the guns and material. The mine will be ready in a day or two, but will not be loaded or sprung till the effect of our operations against the salient is ascertained.

GEO. G. MEADE,

Major-General.

[Inclosure.]

HEADQUARTERS ARMY OF THE POTOMAC, July 16, 1864.

Major-General HUMPHREYS:

In compliance with the direction of the general commanding to furnish a report as to the time which would probably be required to withdraw the siege train and material in case it should be desirable, I have to state that the siege material which will be brought into requisition if operations are fully entered upon will be: Forty siege guns, for which must be kept on hand in the magazines for daily supply, 6,000 rounds of ammunition; for 6,000 rounds 100 wagons are required; for 30 mantlets 10 wagons; 40 platforms 40 wagons; implements, equipage, &c., 10 wagons; 20 8-inch mortars 20 wagons; 3,000 rounds of ammunition 60 wagons; implements and equipage 20 wagons; 20 10-inch mortars, &c., 100 wagons; 20 Coehorn mortars and ammunition 30 wagons; total, 410 wagons. Twenty more 8-inch mortars are expected for the siege train, and if received will be used. To move them there will be required another 100 wagons. The loading of the material in order to withdraw it must be done by night, and probably even then under fire. The movement of so many wagons can scarcely be made and the noise of loading heavy bodies finished without being heard by the enemy when the lines are so near, as in this case; nor will it do to sacrifice any portion of the material if there is any prospect of its being needed within a month. But little over half the supply of ammunition estimated for has yet been received, although it is sent forward as rapidly as it can be procured. The time needed to load the wagons will be necessarily much longer than ordinarily required at depots. For instance, the positions of the batteries were not selected with any reference to convenience in this respect, and but few wagons can be brought up at a time or placed in favorable positions for loading, so that the number of men who can be employed at any given place will necessarily be limited. At many of the batteries the inconvenience and danger of providing the daily supply of ammunition will make a system of covered ways necessary for the men who transport it from wagons stationed so far in the rear as to find cover from the enemy's fire, and also from the approach of the wagons to these points. Time, therefore, becomes the most important element; forty-eight hours would, therefore, be necessary, under favorable circumstances, to remove the material. I do not think it probable that the entire train could be withdrawn in less than three days. The guns and platforms should be moved last, as their disappearance at an earlier time would warn the enemy of the movement in progress. For these reasons the planting of the batteries should not be commenced until it is determined to carry through the siege operations, or, as an alternative, in case a sudden movement of the army should be deemed advisable, we are prepared to sacrifice a large portion of our material.

Respectfully,
H. J. HUNT,

Brigadier-General and Chief of Artillery.