The _Western Expositor_ of Saturday last announces the arrival of Mr. Wm. Gilpin, formerly of this place, from Oregon. Mr. Gilpin passed the winter among the American settlements of the Willamette and the adjacent sea coast, and he describes them as enjoying prosperity when he left them in April last. The emigrant party of '43, which he accompanied, arrived at their destination in November last, "after having braved and overcome unparalleled dangers and difficulties from savages, from hunger, from thirst, crossing parched treeless plains, fierce angry rivers, and forcing their wagons through 1000 miles of mountains, declared impassable by the most experienced guides and voyageurs." This accession swelled the population of Oregon to upwards of 2000, and they had formed a government, elected officers, established courts, and a record of land titles. "Farms," he says, "freckle the magnificent plains, towns are springing up at convenient points upon the rivers, a dozen of excellent mills supply lumber and flour for home use and export; the fisheries are not neglected, and lands are surveyed. A college, numerous schools, and several churches are scattering education amongst the young. Money has been sent from New York for a printing press and steam engine, cattle and stock of all kinds are accumulating and rapidly increasing under a mild climate and unfailing pastures. Provisions of all kinds are abundant, of most excellent quality and moderate prices." Mr. Gilpin passed the trading fort of Bridger and Vasquez on the 19th of August. This fort is 100 miles west of Green River, and exactly half way from Independence to the Willamette. The American trappers scattered among the mountains had there collected to meet the emigrants of last spring; an advanced party of 30 of whom, with their wagons and cattle, passed on the 17th, two days later than the emigrants of the preceding year. Two larger companies behind, under the command of Gen. Gilliam and Col. Ford, passed subsequently, and all in good time reached the settlements before the setting in of winter. * * * * * _Reveille_, January 20, 1845. OREGON. We learn from a letter published in the _Weston Journal_, dated at the Sandwich Islands, that the Oregon emigrants who went out during the past season, have made great changes in business, money now circulating, and everything begins to assume the appearance of the civilization, business, trade, and refinements this side of the mountains. * * * * * _Republican_, February 8, 1848. OREGON.