material changes in the armament would require changes in the platforms or embrasures, involving considerable work, and be likely to produce confusion in the ammunition, besides introducing to the garrisons pieces with whose ranges they would be unacquainted. For these reasons we do not think it will be judicious to disturb the armament of the works at the present time, nor do I suppose that such was your intention in calling my attention to the fact that it might be well to place in the forts some additional field pieces, it being understood, however, that these pieces are to be used in almost every case in the exterior batteries to the right and left of the forts.

it is true that some of the forts, particularly Fort Reno, ought to have some additional field guns for use in the fort, when the enemy approaches within short range, but the theory upon which the defense line is arranged is that all, or nearly all, the additional guns that may be required in case of an investment, or even an assault, are to be placed in the batteries to the right and left of the forts, all the principal forts being supported and generally flanked on both sides by batteries placed in commanding positions. It has been supposed that these field guns would be brought into the defenses by an army retreating before superior numbers, but from our recent experience we have seen that the enemy may succeed in appearing before our works before this additional artillery, or even the troops, can get here. Such being the case, it may be well to inquire whether some of the more important batteries on the line of defense ought not to be armed at once, or field pieces, with ammunition, placed in the forts ready to arm them, and hold the enemy in check, for some days, at least, in order to give time to re-enforce the garrison of the city. Having the officers whom I have mentioned to advise me, I thought it well to look into the whole subject in order that we might have an understanding, and put on record what additional field guns it will be well to have on hand, and where they should be placed on the approach of the enemy at any future time. The following is the result of the consultation on this subject:

LINE NORTH OF THE CITY.

Fort Sumner. - To have additional field pieces; two to be placed on the line of the conduit to hold the bank between Fort Sumner and the river; two in Battery Benson, or Powder Mill Branch, and two in Fort Sumner, or Battery Alexander, as may be required.

Fort Simmons. - Six field pieces to be added; two to be placed in Battery Bailey, on Powder Mill Branch; two in Battery Mansfield, and two held in reserve, or placed in the batteries between Fort Simmons and Fort Bayard.

Fort ReNumbers - Should have four additional field pieces to complete the armament. In case of attack two or three light batteries should at once to be sent to this important post, taking position at first on the ridge between Tennallytown and Fort Gaines.

Battery Russell. - Being an inclosed work with a magazine, and occupying an important position on the right of Fort Reno, should be armed with two field howitzers, 24 or 32 pounders, and four 12-pounder field guns.

Fort Kearny. - There should be four light field guns added to this fort to arm Battery Terrill.