AT SEA.--I have emerged from my berth this morning for the first time since we left the Capes. We have been running six or seven days before a strong northwest gale, which, by the scuds in the sky, is not yet blown out, and my head and hand, as you will see by my penmanship, are anything but at rights. If you have ever plunged about in a cold rain-storm at sea for seven successive days, you can imagine how I have amused myself. I wrote to you after my pilgrimage to the tomb of Washington. It was almost the only object of natural or historical interest in our own country that I had not visited, and that seen, I made all haste back to embark, in pursuance of my plans of travel, for Europe. At Philadelphia I found a first-rate merchant-brig, the Pacific, on the eve of sailing for Havre. She was nearly new, and had a French captain, and no passengers--three very essential circumstances to my taste--and I took a berth in her without hesitation. The next day she fell down the river, and on the succeeding morning I followed her with the captain in the steamboat. Some ten or fifteen vessels, bound on different voyages, lay in the roads waiting for the pilot boat; and, as she came down the river, they all weighed anchor together and we got under way. It was a beautiful sight--so many sail in close company under a smart breeze, and I stood on the quarter-deck and watched them in a mood of mingled happiness and sadness till we reached the Capes. There was much to elevate and much to depress me. The dream of my lifetime was about to be realized. I was bound to France; and those fair Italian cities, with their world of association and interest were within the limit of a voyage; and all that one looks to for happiness in change of scene, and all that I had been passionately wishing and imagining since I could dream a day-dream or read a book, was before me with a visible certainty; but my home was receding rapidly, perhaps for years, and the chances of death and adversity in my absence crowded upon my mind--and I had left friends--(many--many--as dear to me, any one of them, as the whole sum of my coming enjoyment), whom a thousand possible accidents might remove or estrange; and I scarce knew whether I was more happy or sad. We made Cape Henlopen about sundown, and all shortened sail and came to. The little boat passed from one to another, taking off the pilots, and in a few minutes every sail was spread again, and away they went with a dashing breeze, some on one course some on another, leaving us in less than an hour, apparently alone on the sea. By this time the clouds had grown black, the wind had strengthened into a gale, with fits of rain; and as the order was given to "close-reef the top-sails," I took a last look at Cape Henlopen, just visible in the far edge of the horizon, and went below.