What we must consider an unusual piece of good fortune has enabled us to present our readers, under this head, with a narrative of very remarkable character, and certainly of very deep interest. The Journal which follows not embodies a relation of the first successful attempt to cross the gigantic barriers of that immense chain of mountains which stretches from the Polar Sea in the north, to the Isthmus of Darien in the south, forming a craggy and snow-capped rampart throughout its whole course, but, what is of still greater importance, gives the particulars of a tour, beyond these mountains, through an immense extent of territory, which, at this day, is looked upon as totally untravelled and unknown, and which, in every map of the country to which we can obtain access, is marked as "an unexplored region." It is, moreover, the only unexplored region within the limits of the continent of North America. Such being the case, our friends will know how to pardon us for the slight amount of unction with which we have urged this Journal upon the public attention. For our own parts, we have found, in its perusal, a degree, and a species of interest such as no similar narrative ever inspired. Nor do we think that our relation to these papers, as the channel through which they will be first made known, has had more than a moderate influence in begetting this interest. We feel assured that all our readers will unite with us in thinking the adventures here recorded unusually entertaining and important. The peculiar character of the gentleman who was the leader and soul of the expedition, as well as its historian, has imbued what he has written with a vast deal of romantic fervor, very different from the luke-warm and statistical air which pervades most records of the kind. Mr. James E. Rodman, from whom we obtained the MS., is well known to many of the readers of this Magazine; and partakes, in some degree, of that temperament which embittered the earlier portion of the life of his grandfather, Mr. Julius Rodman, the writer of the narrative. We allude to an hereditary hypochondria. It was the instigation of this disease which, more than any thing else, led him to attempt the extraordinary journey here detailed. The hunting and trapping designs, of which he speaks himself, in the beginning of his Journal, were, as far as we can perceive, but excuses made to his own reason, for the audacity and novelty of his attempt. There can be no doubt, we think (and our readers will think with us,) that he was urged solely by a desire to seek, in the bosom of the wilderness, that peace which his peculiar disposition would not suffer him to enjoy among men. He fled to the desert as to a friend. In no other view of the case can we reconcile many points of his record with our ordinary notions of human action.

As we have thought proper to omit two pages of the MS., in which Mr. R. gives some account of his life previous to his departure up the Missouri, it may be as well to state here that he was a native of England, where his relatives were of excellent standing, where he had received a good education, and from which country he emigrated to this, in 1784, (being then about eighteen years of age,) with his father, and two maiden sisters. The family first settled in New York; but afterwards made their way to Kentucky, and established themselves, almost in hermit fashion, on the banks of the Mississippi, near where Mills' Point now makes into the river. Here old Mr. Rodman died, in the fall of 1790; and, in the ensuing winter, both his daughters perished of the small-pox, within a few weeks of each other. Shortly afterwards, (in the spring of 1791,) Mr. Julius Rodman, the son, set out upon the expedition which forms the subject of the following pages. Returning from this in 1794, as hereinafter stated, he took up his abode near Abingdon, in Virginia, where he married, and had three children, and where most of his descendants now live.

We are informed by Mr. James Rodman, that his grandfather had merely kept an outline diary of his tour, during the many difficulties of its progress; and that the MS. with which we have been furnished were not written out in detail, from that diary, until many years afterwards, when the tourist was induced to undertake the task, at the instigation of M. Andre Michau, the botanist, and author of the Flora Boreali-Americana, and of the Histoire des Chenes d'Amerique. M. Michau, it will be remembered, had made an offer of his services to Mr. Jefferson, when that statesman first contemplated sending an expedition across the Rocky Mountains. He was engaged to prosecute the journey, and had even proceeded on his way as far as Kentucky, when he was overtaken by an order from the French minister, then at Philadelphia, rcquiring him to relinquish the design, and to pursue elsewhere the botanical inquiries on which he was employed by his government. The contemplated undertaking then fell into the hands of Messieurs Lewis and Clarke, by whom it was successfully accomplished.

The MS. when completed, however, never reached M. Michau, for whose inspection it had been drawn up; and was always supposed to have been lost on the road by the young man to whom it was entrusted for delivery at M. M.'s temporary residence, near Monticello. Scarcely any attempt was made to recover the papers; Mr. Rodman's peculiar disposition leading him to take but little interest in the search. Indeed, strange as it may appear, we doubt, from what we are told of him, whether he would have ever taken any steps to make public the results of his most extraordinary tour; we think that his only object in re-touching his original Diary was to oblige M. Michau. Even Mr. Jefferson's exploring project, a project which, at the time it was broached, excited almost universal comment, and was considered a perfect novelty, drew from the hero of our narrative, only a few general observations, addressed to the members of his family. He never made his own journey a subject of conversation; seeming, rather, to avoid the topic. He died before the return of Lewis and Clarke; and the Diary, which had been given into the hands of the messenger for delivery to M. Michau, was found, about three months ago, in a secret drawer of a bureau which had belonged to Mr. Julius R. We do not learn by whom i was placed there — Mr. R.'s relatives all exonerate him from the suspicion of having secreted it; but, without intending any disrespect to the memory of that gentleman, or to Mr. James Rodman, (to whom we feel under especial obligation,) we cannot help thinking that the supposition of the narrator's having, by some means, reprocured the package from the messenger, and concealed it where it was discovered, is very reasonable, and not at all out of keeping with the character of that morbid sensibility which distinguished the individual.

We did not wish, by any means, to alter the manner of Mr. Rodman's narration, and have, therefore, taken very few liberties with the MS., and these few only in the way of abridgment. The style, indeed, could scarcely be improved — it is simple and very effective; giving evidence of the deep delight with which the traveller revelled in the majestic novelties through which he passed, day after day. There is a species of affectionateness which pervades his account, even of the severest hardships and dangers, which lets us at once into the man's whole idiosyncrasy. He was possessed with a burning love of Nature; and worshipped her, perhaps, more in her dreary and savage aspects, than in her manifestations of placidity and joy. He stalked through that immense and often terrible wilderness with an evident rapture at his heart which we envy him as we read. He was, indeed, the man to journey amid all that solemn desolation which he, plainly, so loved to depict. His was the proper spirit to perceive; his the true ability to feel. We look, therefore, upon his MS. as a rich treasure — in its way absolutely unsurpassed — indeed, never equalled.

That the events of this narrative have hitherto lain perdus; that even the fact of the Rocky Mountains having been crossed by Mr. Rodman prior to the expedition of Lewis and Clarke, has never been made public, or at all alluded to in the works of any writer on American geography, (for it certainly never has been thus alluded to, as far as we can ascertain,) must be regarded as very remarkable — indeed, as exceedingly strange. The only reference to the joumey at all, of which we can hear in any direction, is said to be contained in an unpublished letter of M. Michau's, in the possession of Mr. W. Wyatt, of Charlottesville, Virginia. It is there spoken of in a casual way, and collaterally, as "a gigantic idea wonderfully carried out." If there has been any farther allusion to the journey, we know nothing of it.

Before entering upon Mr. Rodman's own relation, it will not be improper to glance at what has been done by others, in the way of discovery, upon the North-Western portion of our continent. If the reader will turn to a map of North America, he will be better enabled to follow us in our observations.

It will be seen that the continent extends from the Arctic ocean, or from about the 70th parallel of north latitude, to the 9th; and from the 56th meridian west of Greenwich, to the 168th. The whole of this immense extent of territory has been visited by civilized man, in a greater or less degree; and indeed a very large portion of it has been permanently settled. But there is an exceedingly wide tract which is still marked upon all our maps as unexplored, and which, until this day, has always been so considered. This tract lies within the 60th parallel on the south, the Arctic Ocean on the north, the Rocky Mountains on the west, and the possessions of Russia on the east. To Mr. Rodman, however, belongs the honor of having traversed this singularly wild region in many directions; and the most interesting particulars of the narrative now published have reference to his adventures and discoveries therein.

Perhaps the earliest travels of any extent made in North America by white people, were those of Hennepin and his friends, in 1698 — but as his researches were mostly in the south, we do not feel called upon to speak of them more fully.

Mr. Irving, in his Astoria, mentions the attempt of Captain Jonathan Carver, as being the first ever made to cross the continent from the Atlantic to the Pacific Ocean; but in this he appears to be mistaken; for we find, in one of the journals of Sir Alexander Mackenzie, that two different enterprises were set on foot, with that especial object in view, by the Hudson Bay Fur Company, the one in 1758, the other as early as 1749; both of which are supposed to have entirely failed, as no accounts of the actual expeditions are extant. It was in 1763, shortly after the acquisition of the Canadas by Great Britain, that Captain Carver undertook the journey. His intention was to cross the country, between the forty-third and forty-sixth degrees of north latitude, to the shores of the Pacific. His object was to ascertain the breadth of the continent at its broadest part, and to determine upon some place, on the western coast, where government might establish a post to facilitate the discovery of a north-west passage, or a communication between Hudson's bay, and the Pacific ocean. He had supposed that the Columbia, then termed the Oregon, disembogued itself somewhere about the straits of Annian; and it was here that he expected the post to be formed. He thought, also, that a settlement in this neighborhood would disclose new sources of trade, and open a more direct cornmunication with China, and the British possessions in the East Indies, than the old route afforded, by the Cape of Good Hope. He was baffled, however, in his attempt to cross the mountains.

In point of time, the next important expedition, in the northern portion of America, was that of Samuel Hearne, who, with the object of discovering copper mines, pushed north-westwardly during the years 1769, '70, '71, and'72, from the Prince of Wales' Fort, in Hudson's bay, as far as the shores of the Arctic ocean.

We have, after this, to record a second attempt of Captain Carver's, which was set on foot in 1774, and in which he was joined by Richard Whitworth, a member of Parliament, and a man of wealth. We only notice this enterprize on account of the extensive scale on which it was projected; for in fact it was never carried into execution. The gentlemen were to take with them fifty or sixty men, artificers and mariners, and, with these, make their way up one of the branches of the Missouri, explore the mountains for the source of the Oregon, and sail down that river to its supposed mouth, near the straits of Annian. Here a fort was to be built, as well as vessels for the purpose of farther discovery. The undertaking was stopped by the breaking out of the American revolution.

As early as 1775, the fur trade had been carried by the Canadian missionaries, north and west to the banks of the Saskatchawine river, in 53 north latitude, 102 west longitude; and, in the beginning of 1776, Mr. Joseph Frobisher proceeded, in this direction, as far as 55, N. and 103, W.

In 1778, Mr. Peter Bond, with four canoes, pushed on to the Elk river, about thirty miles south of its junction with the Lake of the Hills.

We have now to mention another attempt, which was baffled at its very outset, to cross the broadest portion of the continent from ocean to ocean. This attempt is scarcely known by the public to have been made at all, and is mentioned by Mr. Jefferson alone, and by him only in a cursory way. Mr. J. relates that Ledyard called upon him in Paris, panting for some new enterprise, after his successful voyage with Captain Cook; and that he (Mr. J.) proposed to him that he should go by land to Kamschatka, cross in some of the Russian vessels to Nootka Sound, fall down into the latitude of the Missouri, and then, striking through the country, pass down that river to the United States. Ledyard agreed to the proposal provided the permission of the Russian government could be obtained. Mr. Jefferson succeeded in obtaining this; and the traveller, setting out from Paris, arrived at St. Petersburgh after the Empress had left that place to pass the winter at Moscow. His finances not permitting him to make unnecessary stay at St. P., he continued on his route with a passport from one of the ministers, and, at two hundred miles from Kamschatka, was arrested by an officer of the Empress, who had changed her mind, and now forbade his proceeding. He was put into a close carriage, and driven day and night, without stopping, till he reached Poland, where he was set down and dismissed. Mr. Jefferson, in speaking of Ledyard's undertaking, erroneously calls it "the first attempt to explore the western part of our northern continent."

The next enterprise of moment was the remarkable one of Sir Alexander Mackenzie, which was prosecuted in 1789. He started from Montreal, pushed through the Utawas river, Lake Nipissing, Lake Huron, around the northern shore of Lake Superior, through what is called the Grand Portage, thence along Rain River, the Lake of the Woods, Bonnet Lake, the upper part of Dog-Head Lake, the south coast of Lake Winnipeg, through Cedar Lake and past the mouth of the Saskatchawine, to Sturgeon Lake; thence again, by portage, to the Missinipi, and through Black Bear, Primo's and Buffalo Lakes, to a range of high mountains running N. E. and S. W. — then taking Elk river to the Lake of the Hills — then passing through Slave river to Slave Lake — around the northern shore of this latter to Mackenzie's river, and down this, lastly, to the Polar Sea — an immense journey, during which he encountered dangers innumerable, and hardships of the severest kind. In the whole of his course down Mackenzie's river to its embouchure, he passed along the bottom of the eastern declivity of the Rocky Mountains, but never crossed these barriers. In the spring of 1793, however, starting from Montreal and pursuing the route of his first journey as far as the mouth of the Unjigah or Peace River, he then turned off to the westward, up this stream, pushed through the Mountains in latitude 56, then proceeded to the south until he struck a river which he called the Salmon (now Frazer's) and following this, finally reached the Pacific in about the 40th parallel of N. L.

The memorable expedition of captains Lewis and Clarke was in progress during the years 1804, '5, and '6. In 1803, the act for establishing trading houses with the Indian tribes being about to expire, some modifications of it (with an extension of its views to the Indians on the Missouri) were recommended to Congress by a confidential Message from Mr. Jefferson, of January 18th. In order to prepare the way, it was proposed to send a party to trace the Missouri to its source, cross the Rocky Mountains, and follow the best water communication which offered itself thence to the Pacific ocean. This design was fully carried out; captain Lewis exploring (but not first "discovering" as Mr. Irving relates) the upper waters of the Columbia river, and following the course of that stream to its embouchure. The head waters of the Columbia were visited by Mackenzie as early as 1793.

Coincident with the exploring tour of Lewis and Clarke up the Missouri, was that of Major Zebulon M. Pike up the Mississippi, which he succeeded in tracing to its source in Itasca Lake. Upon his return from this voyage he penetrated, by the orders of government, from the Mississippi westwardly, during the years 1805, '6, and '7, to the head waters of the Arkansas (beyond the Rocky Mountains in latitude 40 N.) passing along the Osage and Kanzas rivers, and to the source of the Platte.

In 1810, Mr. David Thompson, a partner of the North West Fur Company, set out from Montreal, with a strong party, to cross the continent to the Pacific. The first part of the route was that of Mackenzie in 1793. The object was to anticipate a design of Mr. John Jacob Astor's — to wit, the establishment of a trading post at the mouth of the Columbia. Most of his people deserted him on the eastern side of the mountains; but he finally succeeded in crossing the chain, with only eight followers, when he struck the northern branch of the Columbia, and descended that river from a point much nearer its source than any white man had done before.

In 1811, Mr. Astor's own remarkable enterprise was carried into effect — at least so far as the joumey across the country is concerned. As Mr. Irving has already made all readers well acquainted with the particulars of this journey, we need only mention it in brief. The design we have just spoken of. The track of the party (under command of Mr. Wilson Price Hunt) was from Montreal, up the Utawas, through Lake Nipissing, and a succession of small lakes and rivers, to Michilimackinac, or Mackinaw — thence by Green Bay, Fox and Wisconsin rivers, to the Prairie du Chien — thence down the Mississippi to St. Louis — thence up the Missouri, to the village of the Arickara Indians, between the 46th and 47th parallels of N. latitude, and fourteen hundred and thirty miles above the mouth of the river — thence, bending to the southwest across the desert, over the mountains about where the head waters of the Platte and Yellowstone take rise, and, along the south branch of the Columbia, to the sea. Two small return parties from this expedition made most perilous and eventful passages across the country.

The travels of major Stephen H. Long are the next important ones in point of time. This gentleman, in 1823, proceeded to the source of St. Peter's river, to Lake Winnipeg, to the Lake of the Woods, etc., etc. Of the more recent journeys of Captain Bonneville and others it is scarcely necessary to speak, as they still dwell in the public memory. Captain B.'s adventures have been well related by Mr. Irving. In 1832, he passed from Fort Osage across the Rocky Mountains, and spent nearly three years in the regions beyond. Within the limits of the United States there is very little ground which has not, of late years, been traversed by the man of science, or the adventurer. But in those wide and desolate regions which lie north of our territory, and to the westward of Mackenzie's river, the foot of no civilized man, with the exception of Mr. Rodman and his very small party, has ever been known to tread. In regard to the question of the first passage across the Rocky Mountains, it will be seen, from what we have already said, that the credit of the enterprize should never have been given to Lewis and Clarke, since Mackenzie succeeded in it, in the year 1793; and that in point of fact, Mr. Rodman was the first who overcame those gigantic barriers; crossing them as he did in 1792. Thus it is not without good reason that we claim public attention for the extraordinary narrative which ensues.