THE EXPLORATIONS OF FREMONT.—–­ Among the earliest efforts of Fremont, after he had tried and been sickened by the sea, were his experiences as a surveyor and engineer on railroad lines from Charleston to Augusta, Ga., and Charleston to Cincinnati.  Then he accompanied an army detachment on a military reconnoissance of the mountainous Cherokee country in Georgia, North Carolina and Tennessee, made in the depth of winter.  In 1838-9 he accompanied M. Nicollet in explorations of the country between the Missouri and the British line, and his first detail of any importance, after he had been commissioned by President Van Buren, was to make an examination of the river Des Moines, then on the Western frontier.  In 1841 he projected his first trans-continental expedition, and left Washington May 2, 1842, and accomplished the object of his trip, examined the South Pass, explored the Wind River mountains, ascended in August, the highest peak of that range, now known as Fremont’s Peak, and returned, after an absence of four months.  His report of the expedition attracted great attention in the United States and abroad.  Fremont began to plan another and a second expedition.  He determined to extend his explorations across the continent; and in May, 1843, commenced his journey with thirty-nine men, and September 6, after traveling over 1,700 miles, arrived at the Great Salt Lake; there made some important discoveries, and then pushed on to the upper Columbia, down whose valley he proceeded to Fort Vancouver, near its mouth.  On Nov. 10, he set out to return East, selecting a southeasterly course, leading from the lower part of the Columbia to the upper Colorado, through an almost unknown region, crossed by high and rugged mountains.  He and his party suffered incredible hardships in crossing from the Great Basin to Sutter’s Fort on the Sacramento; started from there March 24, proceeded southward, skirted the western base of the Sierra Nevada, crossed that range through a gap, entered the Great Basin; again visited the Great Salt Lake, from which they returned through the South Pass to Kansas, in July, 1844, after an absence of fourteen months.  In the spring of 1845 Fremont set out on a third expedition to explore the Great Basin and the maritime region of Oregon and California; spent the summer examining the headwaters of the rivers whose springs are in the grand divide of the continent; in October camped on the shores of the Great Salt Lake:  proceeded to explore the Sierra Nevada, which he again crossed in the dead of winter; made his way into the Valley of the San Joaquin; obtained permission, at Monterey, from the Mexican authorities there, to proceed with his expedition, which permission was almost immediately revoked, and Fremont peremptorily ordered to leave the country without delay, but he refused, and a collision was imminent, but was averted, and Fremont proceeded toward San Joaquin.  Near Tlamath Lake, Fremont met, May 9, 1846, a party in search of him, with dispatches from Washington, ordering