We have been favored with the perusal of a private letter from Bent's Fort, dated July 26. The writer is one of Mr. Fitzpatrick's party, and says that thus far their trip has been a severe one. The party has been delayed since the 14th inst., waiting for the arrival of Mr. Fremont, who left them on the 17th of June with 18 men. After progressing ahead some distance, he despatched an express back, requesting the rear party with Fitzpatrick not to move until he joined them, alleging as a reason that there were hostile Mexicans on their route. On the morning of the date of the letter, the writer says, they were dividing into two parties again, with the intention of meeting at Ft. Hall, Oregon, in about 4 days [weeks]. Fitzpatrick's party intended crossing the Platte that morning, and would take up its line of march over the mountains. He speaks of a slight difficulty with the Indians, but furnishes no particulars. * * * * * _Republican_, Friday, September 29, 1843. We have received from Mr. Edward Hutwa a very handsome, and, as far as we have any means of judging, a correct lithograph map of the Oregon Territory, as claimed by the U. S., with a portion of the adjacent territory. The principal rivers, mountains, routes, trading depots, and the trading depots and forts of the Hudson's Bay Co., are laid down with accuracy. To those migrating to the Columbia, or to those wishing to study the topography of the country, this map will be of importance. * * * * * _Republican_, Wednesday, December 13, 1843. A postscript to a letter from a gentleman in the Indian country, dated October 19, received by a gentleman of this city, says: "Ft. Hall, on the Oregon has been delivered up to Lt. Fremont, and it is believed that Ft. Vancouver soon will be." How far the report is reliable, we have no means of knowing, except that he and his party are in Oregon by the authority and direction of the United States Government. * * * * * _Republican_, Thursday, December 14, 1843. We yesterday noticed a postscript of a letter from the Oregon country. We have since seen letters from Lt. Fremont and other men of his party, written at Ft. Hall, and bearing date of 20th September, which do not confirm the report alluded to. The silence of these letters as to the surrender of Ft. Hall is full assurance to us that the report is not correct. The letter before us, the statements of which are corroborated by Lt. Fremont, himself, says:--