On Saturday, the 31st of January, 1863, the steamer 'S.R. Spaulding,' flagship of General Foster's fleet, left the harbor of Morehead City, N. C., on a supposed expedition to some point on the Southern coast. For two days we had watched from her deck the long procession of vessels moving slowly round Fort Macon, and then, with all sails set, or under full head of steam, passing proudly on in their southward course. Only those who have witnessed such scenes can realize the eager interest and intense excitement which attend the preparation for a naval expedition. Then, too, there were glories of the past to kindle hope and stimulate ambition. The successes of Burnside, Du Pont, and Farragut were fresh in memory, and why should not we win new laurels for the old flag, and place our commander's name high on the list of fame? And so, with feelings of pride and expectation, we gladly saw the shores of North Carolina with their forests of pines recede from sight, as, under a cloudless sky and over a waveless sea, we glided on toward the hated mother State of the rebellion. The sequel of the 'Foster Expedition' is well known. We anchored, on the 2d of February, in the capacious harbor of Port Royal, and were flagship no longer. Fortunately, the long interval between our arrival and the final departure for Charleston under another commander, gave abundant opportunities for studying new phases of life and character, and for learning something of the 15,000 freedmen who compose the loyal population of the Sea islands. ON THE PLANTATIONS.