The Federal forces to the number of four hundred occupied Pohick church, sixteen miles from Alexandria, on the Fairfax road, Virginia. A force of rebel cavalry, which had held the place, retired hastily with the loss of several wounded. A reconnoissance was then made toward Occoquan, during which important discoveries were made.
A balloon was seen passing over Washington, and it was thought by many to have started from the rebel camp, on an aerial reconnoissance; but as it subsequently descended in Maryland it proved to be the air ship of La Mountain, which had ascended from the Union  camp of the Potomac. It appears that when La Mountain rose to a certain distance he cut the rope which connected his balloon with the earth, regardless of the danger, and soared up to an elevation of a mile and a half, and got directly over the rebel lines. Here he was enabled to make a perfect observation of their position and all their movements, the results of which he has communicated to Headquarters, and which are said to be of the utmost importance. When La Mountain completed his observation, he threw out sufficient ballast to enable him to rise to a height of three miles, when he fell in with a counter current which carried him back in the direction of Maryland, thus passing over Washington.
Commander Alden, of United States steamer South Carolina, reports to Flag-officer McKean, Gulf Squadron, the capture of two schooners off the Southwest Pass of the Mississippi, with from four to five thousand stand of arms.--(Doc. 68.)
A party of New Mexican Union volunteers, under Captain Mink, was surprised at Alimosa, thirty-five miles below Fort Craig, by one hundred and ten Texan rebels, and their horses stampeded. Captain Mink proposed to surrender his company; but his men dissented, secured their horses, and retreated to Fort Craig. Subsequently about one hundred United States troops, from Fort Craig, pursued the rebels, overtook them, killed their captain and ten men, wounded about thirty, and killed thirty horses. The balance of the Texans escaped to Mesilla.