The Atalanta.- Whether the class of vessels are at all improving it is rather difficult to determine, but it is certain the Atalanta has accomplished a very good passage of 81 days, and had the weather from the Leuwin continued favourable she would certainly have reached the lightship in 75 days; but contrary winds set in, preventing so desirable a conclusion to so prosperous a voyage. She left Plymouth on January 23, and was three days before she cleared the Channel, owing to the heavy gale from west and west-south-west, which blew with extreme violence. The Island of Madeira was passed on February 2; on the 27th day out crossed the Line, on February 19, and here was struck by prevailing calms for several days. After rounding the Cape, on March 17, she had some very favourable sailing until reaching the Cape Leuwin, on April 4, from which time head winds and calms were the only entries in the logbook. On April 3, in lat. 41°38'S., long 108°33'E.,one of the seaman was lost overboard, a melancholy termination to the life of a tar. It appears he was engaged in putting a stop on one of the flying jibguys when he fell, and as the vessel was heading at about 12 knots per hour the life-buoys were thrown in vain. The helm was put hard down, bringing the ship to the wind, and throwing all aback. One of the life-boats was lowered in a high sea, but it was impossible to save the poor fellow. His name was William Moore, and he was rather a favourite among those shipmates who deplored his untimely loss. The Pilot boarded when to the westward of Glenelg, and at first expected she would moor in harbour during the day; but on bringing up, the draught, instead of being 17, was discovered to be 18 feet 9 inches. When a large quantity of cargo had been shifted, to bring the ship as near as possible on even keel, the evening tide would not allow her to pass over the bar, and in consequence she will remain outside till about Wednesday or Thursday. Register 16/4/1866 With 392 Souls; Government Assisted Migrants.