Alexandria Gazette, Commercial And Political

WASHINGTON CITY, July 19.

One of the Editors returned from head-quarters on Saturday night. The last accounts left the British squadron, consisting of two frigates, two sloops of war and two tenders, off Swan's Point. This is all the force ascertained. Other force was reported to be lower down, its amount variously stated. A detachment of cavalry had proceeded with Col. Monroe down the river, to ascertain and examine the force below.

The following disposition has been made of the troops at and near Fort Washington (Warburton) A strong detachment of United States' artillery, under the command of captain Ritchie, occupies the fort. The covering work & the ridge on which it stands, are held by a battalion of the 10th, one company of the 26th United States infantry, commanded by Capt. Brooks; major King's battalion of dragoons, & a detachment from Capt. Burch's company, with their field pieces, the whole under the command of Col. Nicoll of the first regiment of United States artillery.
On the road leading from Piscataway to Port Tobacco, are posted the dragoons, supported by Capt. Davidson's infantry, Capt. Stull's riflemen, the Georgetown grenadiers under the command of Capt. Edmonston, Capt. Ruth's, Capt. Cassin's, Capt. Lenox's and Capt. Young's infantry.

Still further in the rear, and nearer the point where the Warburton and Washington City roads meet, is the 36th regt under the command of Col. Carberry, with the remainder of Capt. Burch's artillery. This disposition, while it guards against the enemy's approach, whether by land or water, admits of a ready concentration of our force on either point of attack. Besides the above, Capt. Peter's artillery went down from Georgetown on Saturday, but had not been stationed when we heard from them.

If there should prove to be no other force in the Potomac than that which is stated, a small part of the force now in service would be amply sufficient to keep it in check.