I sent a dispatch to the captain of the gunboat, urging his to proceed to the ferry, but on its arrival, about 11 o'clock, at the point, the gunboat had left and gone in the direction of Saint Helena Sound. Such is the report of Lieutenant Lyons, who bore my dispatch.

I will again urge with all possible earnestness that a gunboats be sent without delay up Broad River and through the Port Royal passage, and if this meets your approval, I trust you may succeed in getting Commodore DuPont to dispatch one to-day. I shall telegraph to this effect this morning.

It is my propose to go to the ferry in the course of an hour or two, and remain there until to-morrow evening; but I shall make arrangements to have your dispatches forwarded without delay.

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

ISAAC I. STEVENS,

Brigadier-General, Commanding.

[Inclose Numbers 1.] HEADQUARTERS PORT ROYAL FERRY,

December 15, 1861.

General ISSAC I. STEVENSONS,

Commanding Port Royal District:

SIR: I have to report that no demonstration of a hostile character has occurred on the part of the enemy since my last dispatch, save a report (verbally from Captain Elliott, Company, Seventy-ninth New York Regiment, that 400 men appeared last evening on the shore occupied by the enemy about 1 mile above Seabrook. Captain Elliott reports, through Major Marrison, that he mounted a long on two kart-wheels and ran it on the beach, which had the effect to scatter the enemy in all directions.

Lieutenant-Colonel Brenholts, accompanied by Lieutenant Kellogg, Company K, Fiftieth Pennsylvania Regiment, with four men, left Port Royal Ferry yesterday morning at 9 o'clock and proceeded down the river (on our right) 2 1\2 miles, taking soundings of the channel 1\2 miles below the ferry (on right). Stockades were driven and timer sunk, so as to leave but 7 feet of water in the channel at low tide, but the obstruction does not extend half way across the river. Our side of the channel is clear (the enemy some cause or other having abandoned the work before finishing it.) I wish it distinctly understood that I am correct in this, that not one-half the channel is obstructed; that the obstruction are all on the enemy's side, and, if necessary, could be easily removed; further, that Lieutenant-Colonel Brenholts report outside of the obstructions a channel 112 feet wide 12 feet of water at low tide and 19 feet of water at high tide. This is reliable, and, so far as our observations extend, no other obstructions exist in the channels.

Our pickets are so posted as to command the shore from Seabrok to a point opposite a brick-yard 2 1\2 or 3 miles below the ferry (our right), said brick-yard being separated from that portion of the island we occupy by a stream, supposed to be the outlet of the stream crossed by a bridge 4 miles from Beaufort. Discovered that the point on which the brickyard is located is occupied by a detachment from the Eight Michigan Regiment, under Captain Elder. Pickets have been posted from the point last indicated to Seabrook, and every precaution taken to guard against surprise. I would add the on the opposite shore, 2 miles below the ferry (our right), what was supposed at first to be a picket station of the enemy on a more careful examination proves to be an