SOUTHEND, ESSEX.—During a strong gale from the S.W. and a rough sea on the 2nd September the brig Avenir, of and for Krageroe, Norway, from London, in ballast, parted both her anchors and drifted on1 to the Maplin Sands. The No. 1 Life-boat Soys of England and Edwin J. Brett was launched at 2 P.M., proceeded to the vessel and remained by her until the flood tide made on the following day, when, with the assistance of a steam tug, she was gotafloat and towed to Gravesend. She had a crew of seven men..