EMIGRATION or MORMONS.—The Liverpool Mercury of the 10th instant says: "On Monday last the Ellen sailed from this port for New Orleans, having on board 466 emi-grants, on their way to the Mormon settlement in the valley of the Great Salt Lake. The emigrants were from all parts of England—fifteen families coming from Sheffield alone. A second ship, the George William Brown, is also ready to sail, with about 280 emigrants of the same persuasion, and for the same destination, whilst another vessel, the Ellen Maria, has been lard on to sail on the 29th instant. Mr. Orson Pratt, the head of the sect, and who is an emigration agent in this town, will take his passage by this. This emi-gration is of a most extraordinary and romantic character; the subsequent journey would appal the stoutest heart, not upheld by religious fervor or fanaticism. The poor emigres from New Orleans proceed up the river as far as Council Bluff, nine hundred miles north of St. Louis. They will there prepare for the overland journey across the plain to the Salt Lake Valley, a distance of one thousand miles, which has to be performed in wagons, and their journey lies across a tract of country almost entirely destitute of herbage."