I have the honor to inclose herewith copies of all official messages received on that day of which record was made.

With the exception of the station upon Washington Monument, which failed to communicate with Hagerstown, the officers on duty were every-where on the alert, and the orders given them successfully obeyed. The case of an officer absent from his station is now under investigation. I have only to regret that the efforts of those who well did their duty were not followed by successes to our arms, to which they could claim to have contributed.

I am, general, very respectfully, your obedient servant,

ALBERT J. MYER,

Signal Officer and Major U. S. Army.

Brigadier General S. WILLIAMS,

Assistant Adjutant-General, Army of the Potomac.

[Inclosure A.]

ALBERT J. MYER,

Signal Officers and Major U. S. Army:

SIR: In compliance with orders from Headquarters Army of the Potomac, I have the honor to report that, on October 10, 1862, our signal party was surprised by a body of rebel cavalry, about 8 a. m., approaching the station. During the morning, the valley along the river was filled with a dense fog, which prevented seeing any portion of the river. The point at which the rebels crossed the river is hid hid entirely from view from any point on this mountain; also, the road over which force came after leaving the river is not visible, not even the slightest portion of it, from any place upon this mountain. The turnpike leading over, the mountain, and which they crossed about 1 mile below our station, is winding, and can be seen from no one point, but at a very few rods from our station it can be seen about 20 rods. Here it was we first saw the rebel cavalry approaching. They were on us in a very short time from our first seeing them. We had just succeed unsaddling our horses, at least part of us; Privates Vincent and Emge had not finished saddling theirs, which accounts for their capture. They were trying to save their horses with themselves. The men lost all their extra clothing, 3 McClellan saddles and bridles, 2 horses, 2 full sets flags, 1 saber, 3 pistols, 2 telescopes, 2 marine glasses, and 2 kites, none of which have been recovered.

Lieutenant Roe and myself rode to Clear Spring, about 3 miles from the station, and there reported to Captain Russell, of the First Maryland Cavalry. He immediately sent our dispatch to General Kenly, at Williamsport. We then rode to Hagerstown. Previously to this I had sent a man to Lieutenant Spencer's station, near Hagerstown, with statement of facts. He reported to Lieutenant Spencer about 11 a. m. Lieutenant Spencer Immediately reported the facts to General Brooks, commanding at Hagerstown. Lieutenant Roe and myself reached Hagerstown about 2 p. m., when we immediately reported the facts of crossing and their probable force, with for pieces for artillery, to Generals Franklin and Brooks. We remained at Hagestown all night. Returning to this station the next morning, found every thing quiet, and have remained here since communicating with stations at Williamsport and Hagerstown.

I have the honor to be, respectfully, yours,

W. W. ROWLEY,

Acting Signal Officer.

3 R R-VOL XIX, PT II.