POTOMAC FLOTILLA, January 24, 1862.

Brigadier-General HOOKER, U. S. A.,

Commanding Division, U. S. Army, Lower Potomac:

SIR: In answer to your inquiries of yesterday, I have the honor to inform you that the force at present under my command consist of eleven steamers, scattered from Hallowing Point to Point Lookout. The force of these vessels in battery is four 9-inch shell guns, four 8-inch shell guns, four 32-pounders of 33 hundred-weight; two Parrott rifled 30-pounders, one rifled 50-pounder, three 24-pounder howitzers, and six 12-pounder rifled howitzers. These are all light and extremely vulnerable boats. Their draught of water is from 7 to 9 feet. Two of them are ferry-boats, one drawing 8 feet, the other 4 1\2 feet of water. I judge that they would not carry conveniently more than 1,000 men above the number of their crews; the ferry-boats taking about 600 of this number. I am of opinion that were it desired to cross the river the vessels, with the exsection of the ferry-boats, could render better service in towing launches, barges, &c., loaded with troops, than by taking them open their decks.

From Otterback's farm, above High Point, to within range of the Cockpit battery, below Freestone Point, these vessels can approach the beach within about 200 yards-perhaps somewhat nearer on the north side of Freestone Point, where a landing could be effected on the beach below the bluff. Under Cockpit Point the water is quite deep well up to the shore, and this continues to the Evansport batteries, from below which it runs of shoal again near the Virginia shore. Just above Mathias Point the water is again quite deep, allowing a streamer to go close in..

The enemy appear to be in considerable force in the neighborhood of Occoquan River. A few weeks since they had a full field battery at this point of about 9 to 12 pounders, rifled. Back of Freestone Point, on the road leading to Dumfries, I thinks that there is not more than one regiment. Lately their camp fires have not been so distinct or numerous at these points. About two weeks since two vessels shelled the railroad depot at Aquia Creek. Their batteries did not reply. The next day troops were marched to Aquia, and now I have reason to believe that three regiments are there, and an additional rifled gun placed in their battery at that point, with which they have practiced, without effect, on one of the vessels. There has been an encampment at Hook's Landing, and a field battery drawn occasionally to Boyd's Hole, but lately the battery has disappeared. The camp has been shelled, but I think without effect. It sets too far back for the range of our guns.

This morning I made a reconnaissance of Occoquan Bay. Their main encampment seems to be about 2 miles back from the bay, extending from Occoquan towards Neabsco Creek. Back of Neabsco Creek, near the junction of the roads from Colchester and Occoquan towards Dumfries, there appears to be a considerable breastwork thrown up, but no guns are visible. A body of cavalry was fired upon, but their field battery was not brought down as before.

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

R. H. WYMAN,

Lieutenant, Commanding Potomac Flotilla.