Potomac, but disloyal or suspected persons will be liable to arrest and detention until discharged by competent authority, and contraband articles will be sized.

Officers and soldiers of the Army will obtain passes as heretofore ordered.

All complaints of improper arrests, seizures, or searches, made or purporting to be made under military authority, will be received by the proper brigade commanders or provost-marshals, who will at once investigate the same, and in each instance make report to these headquarters.

By command of Major-General McClellan:

S. WILLIAMS,

Assistant Adjutant-General.

SANDY HOOK, NEAR HARPER'S FERRY,

August 17, 1861.

Colonel E. D. TOWNSEND, Assistant Adjutant-General:

SIR: We greatly need more artillery. Major Doubleday's battery is very heavy for field service. Excluding that, we have but fourteen pieces. This is wholly insufficient for active service int he new position we are to occupy. Captain Tompkins has recruited a company in Rhode Island, which arrived here last night. The battery is in Washington; the company here. Either the battery should be sent to us or the company order to Washington. We wait instructions upon this subject. I most earnestly press upon the Commander-in-Chief our necessities for an increase of artillery, and hope that a liberal supply will be ordered to us for service in the new position we are to occupy.

We leave one regiment at Harper's Ferry, the Second Massachusetts, Colonel Gordon; one at Sharpsburg, Colonel Leonard, Thirteenth Massachusetts; one at Berlin, Colonel Donnelly, Twenty-eighth New York. Colonel Geary is at Point of Rocks since Wednesday night. The rest of our column is en route for a position between Frederick and the Potomac east of the Monocacy, according to the orders to the Commander-in-Chief. The country is quiet in this section. No more than the usual cavalry scouts are seen through hey are more bold and active. Some miles south of Point of Rocks Colonel Gerary observed a force moving in the direction of the Potomac. It is the same probably that has been seen at Lovettsville, and towns in that neighborhood, and is from 1,500 to 2,000 strong. The river is rising and rain falls lightly this morning.

I have the honor to be, sir, your most obedient servant,

N. P. BANKS,

Major-General, Commanding.

HEADQUARTERS DEPARTMENT OF PENNSYLVANIA,
Baltimore, Md., August 17, 1861.

Colonel G. W. CULLUM,

Aide-de-Camp, Headquarters of the Army:

COLONEL: I inclose a map of the city of Baltimore, on which I have marked the eminences we examined in our hastily reconnaissance of yesterday. I have numbered them in the order in which we visited them, and I have added the ascertained elevation of each. A few memoranda may fix more firmly in your mind what you wished to remember: