MONOCACY, August 1, 1864.

Major General L. WALLACE:

Lieutenant Corbit, of Colonel Clendenin's command, has just come in from mouth of Monocacy, reporting all quiet this a. m. He brings one prisoner of Mosby's gang, taken last night, having been secreted since the day before. Lieutenant Corbit is a very reliable officer, and his opinion is that Mosby's force is about 400, with, perhaps, two or three pieces of artillery. The prisoner will be sent you on first train.

E. B. TYLER,

Brigadier-General.

WASHINGTON, August 1, 1864--11. 20 a. m.

Major-General DIX,

Commanding, New York:

Please inform the Chief of Staff if the garrison at Elmira has been increased, or how soon it probably will be.

J. C. KELTON,

Assistant Adjutant-General.

NEW YORK CITY, August 1, 1864.

Lieutenant-Colonel KELTON,

Assistant Adjutant-General:

Governor Seymour has ordered three regiments to report to me for Elmira.

JNO. A. DIX,

Major-General.

PITTSBURG, PA., August 1, 1864.

(Received 4. 25 p. m.)

Honorable E. M. STANTON,

Secretary of War:

I can hear of no enemy in this State except the force Averell followed from McConnellsburg and is after now. Scouts have started for Virginia south of Cumberland to find out about Breckinridge. Have requested General Kelley to do the same. I found considerable excitement in this city. Have directed that two enrollments and organizations be made immediately. The first one includes those ready to march at the call of the Government; the balance of the citizens for home defense. This, I think, gives satisfaction. The civil authorities are acting in harmony with me. As at Harrisburg, I have positively declined to declare martial law.

D. N. COUCH,

Major-General.

PITTSBURG, August 1, 1864.

(Received 12 p. m.)

Major-General HALLECK,

Chief of Staff:

A dispatch from General Averell informs me that last night he prevented the enemy from crossing at Hancock, and forced them to