Parties which I sent out to make prisoners have failed to attain this object. The field glasses which I placed in my lookouts while shelling the enemy's camps all along my line could not discover much, the weather having been quite hazy for the past week. It is, however, a remarkable fact that, although I have used every means to provoke the enemy's fire, I have received no answer from those guns which were formerly manned by the Second South Carolina Heavy Artillery. This fact, and several incidents of smaller importance, lead me to suppose that a change of troops took place on my front shortly after the heavy firing of the enemy along his entire line, reported some time ago. Such a change of troops of course implied a re-enforcement of the enemy for some little time, while the change was being effected.

The silence of the enemy's artillery tends to show that part of the artillery force (perhaps the Second South Carolina) have been sent elsewhere, and have taken their best pieces (those with which they formerly reached our lines from Secessionville and Legare's Point) with them. Cavalry and infantry, perhaps militia, will have taken their places.

My fire on Sunday last, directed at the works on Johnson's Point, to provoke a reply, was promptly answered by the enemy from those works, which are manned by companies of the First South Carolina Artillery. The only method of clearing up this question will be to attack the enemy and make him show his force. I do not consider myself at present authorized to do this without orders from the major-general commanding the department. The enemy's steamboats on Stono River have disappeared, with the exception of one which is anchored above Battery Pringle.

The bridge between Batteries Pringle and Tynes, leading from James to John's Island, the enemy had completed within the last four nights, so far as regards the piles and part of the covering and railing. This bridge has no draw, which precludes the intention on the part of the enemy of coming down the Stono River for offensive purposes with anything larger than torpedo-boats. It further goes to show that the enemy means to defend John's Island by re-enforcements sent from James Island, and this again indicates that the former district of General Wise (Adams' Run, Church Flats, Rantowles Station, and John's Island) is but insufficiently guarded.

The boom across Stono River was laid but sunk, through miscalculation on the part of the captain of engineers; it will be relaid by to-morrow night.

I regret to state that through direct disobedience of my orders by Captain McKenna, First New York Volunteer Engineers,who yesterday landed 6 men at Legareville without a guard, 2 of them were captured by the enemy. The captain of engineers reports that the bomb-proof of Battery Chatfield will be completed this week.

The firing into the city has been kept up as usual. As regards fort Sumter, I have had to repeat my former orders, the firing at the fort having been neglected. The recent high tides have washed away the sand and again exposed the wall perpendicular to the water. Our rifle guns are cutting horizontal and perpendicular lines in this wall to reduce the fort to its former condition and overthrow the repairs lately made by the enemy.

The enemy fired at Fort Putnam from Moultrie three days, throwing each day about 15 or 20 mortar shells. There have not been as