From Charleston

Fokthes9 Momios, Aug. 16, The steamer S. R. Spaulding arrived this morning from off Charleston. The Spaulding reporta having left Morris Island :it 10 o'clock on Friday mornini?. On Thnrsday evening the monitors were all stripped and prepared for action, and at daylight on Friday the batterieson Morris Island openecl their fire which lasted an hour or two, when it ccased. Tho monitors did not fíro a bhot, and as soon as tho battenea ceased firing the monitors put up awnings. No explanation is given for this movement. The strongtist contidence is expressed of a favorable result. Our informant says that during the short engagement on Friday morning ho saw severa! shots strike Fort Sumpter, causing bricks and reortar to fly profusely. One of our officers, who left Morris Island on Friday, says that upon receiving instrnctions in regard to conveying news by Quartermaster Dunton, he asked hirn "What shall I teil our friends at Fortress Monroe?" The Quarterniaster replied : " Teil them a great battle will come off bere on Saturday the 15th, or Sunday the 16th instant, and that wo shall be victorious." Flar-siup üinsmore, I Off Cuarlkston, Aug. 16. { Sinoe Monday evcnts here have been rather monotonous. We have been exchanging shefl and shot with the rebels night and day, probably with but little damage to either srde. Tho enemy's object was to retard Gen. Gifmore's siege worksf but they have aí! been perfected for sevaral duys. The intention to open on the I3th was abandoned on account of soma difficulty as to the quality of army ammunition, and owing to the 8erious ndispositfon of General Gilmore. He is, hawever, much better, and tho opening uf the heavy siege work will commence at ctaylight tomorrow. The shore batterios, in getting the range of guns yesterday aud day before, knocked tlirec holes in tho walls of Suropter. The gereral impression prevails that the rebels are evacuating Sumpter, and will blow it up as soon as the assault commences. Out of noarly thirty guns on the parapeta ten days ago, but ais now remain, and most of those in casements. The rebels have ereeted a line of eartbworks one mile in length on James Island from Fort Johnson to Secessionville, although they have but few guns mounted yet. Thia is supposed to be tho destination of Sumpter's guns. üur pickct boats around Sumpter report great aetivity every night with schoonera, steamers, &c. Everything is now in readiness o& sea and shore, and are looking forward to the work of to-morrow, certain of success. Reinforcements continue toarrive daily andjquito a large army is now on the ialands. Wednesday night the rebels fired on our works with grape and canister. The monitor went ap in the night and opened on Fort Wagtier, and the rebel guns were soon silenced. The Admiral went on board the Patnpsco, joining her nnder the guns of Wügner, and coming near being taken off by a thirty-inch shot. Indications are that tbe rebels will depend prtn-cipally on the obstructions and the interior line of defenses. Io the attack to-morrow the Ironsides will engage Wagner and keep her silent, vvhile the monitors and shore batteries engage Sumpter. The wooden fleet and mortar schoonera will engage Moultrie. It will be a grand aflair. The rebel works on James Island indicate an attempt on the part ol the rebels to drive Gilmore off James Island or to so annoy him as to interfere with his siege of Sumpter.