No attack was made by either army, both apparently gathering renewed strength for the battle we all felt must come. The night passed, and from the station on the mountain we learned next morning that the enemy had fallen back from Sharpsburg to the south bank of the Potomac. With Lieutenants Daniels, Fralick, Carey, Hebrew, and Horner, I joined the advancing cavalry, and opened communication from a position near, where a few hours afterward General Porter located his headquarters. Leaving the station in the charge of lieutenants Hebrew and Horner, and sending Lieutenants Fralick and Daniels to Maryland Heights, I accompanied, by request, General porter to the bank of the river, and received instructions that, as a battery would be quietly placed in position back of a hill, I should prepare my officers to direct the fire of the battery from my position on the bank of the river. I chose to take part myself in preference to sending others, and having been joined By Lieutenant Owen, I sent him to the battery while I resumed the forward position, where we remained during the entire afternoon, signaling the effect of the several shots as the battery played upon the opposite bank.

Saturday, September 20, communication was established with maryland Heights, which has since been kept open from various points. Headquarters having moved forward, Lieutenants Stone and Taylor broke up their stations and established them near the new location. After which, changes were made which will be best understood by giving you a detailed account of the present disposition of the detachment. Commencing with the right, we have at Fairview Lieutenant Rowley and Roe, with instructions to send by signals to Hagerstown reports of observations made, to be received by Lieutenant Spencer and forwarded by telegraph to Major-General McClellan. Near Downsville are Lieutenants Denicke and Clark, communicating with the Headquarters station, through the station on Elk Mountain, at which latter station are Lieutenants Jerome, E. Pierce, and Owen. On the mountain, just east of headquarters, present camp, are Lieutenants Wicker and L. Pierce. At Headquarters station are Lieutenants Stone and Taylor, communicating with station on the right, and Lieutenants Kendall and Gloskoski, communicating with stations on the left. On maryland Heights are stationed Lieutenants Daniels and Hall. On Bolivar Heights, with General Sumner, are Lieutenants Hill And Brook. On Loudoun Heights, with General Greene, are Lieutenants, Halsted and Camp., On Sugar Loaf Mountain are Lieutenants Hebrew, Yates, and Carey, communicating with Lieutenants Dinsmore and Adams at Frederick, the two latter forwarding reports by telegraph. Lieutenant Harvey is on special duty, per order.

Lieutenants Fralick, Barrett, and Wilson are sick, the two latter not seriously. In camp are Captain Fortescue and Lieutenants Horner, Paine, and Collin. Many of the officers need equipments, and are anxiously awaiting the arrival of Lieutenant L. B. Norton, in order to thoroughly prepare the party for another campaign, if called upon during the fall. I look forward to better success and more pleasant duties hereafter. The officers, gathered from different divisions of the army, and not accustomed to each other's mode of working, have become somewhat acquainted during the present campaign, and it can be expected that there will be an understanding and more harmony in the manner of communication. Very respectfully, your obedient servant,

B. F. FISHER,

Captain, Commanding Signal Detachment, Army of the Potomac.

Major A. H. MYER,

Chief Signal Officer.