In extent, in elevation, and in breadth, the _Rocky Mountains_ far exceed the Alleghanies of the Eastern States. Their mean breadth is two hundred miles, and where broadest, three hundred. Their height must be very great, since, when first seen by Captain Lewis, they were at least one hundred and fifty miles distant. On a nearer approach, the sublimity of the prospect is increased, by the appearance of range rising behind range, each yielding in height to its successor, till the most distant is mingled with the clouds. In this lofty region the ranges are covered with snow in the middle of June. From this last circumstance, these ranges have been sometimes denominated the _Shining Mountains_――an appellation much more appropriate than that of the _Rocky_ or _Stony Mountains_, a property possessed by all mountains, but peculiar to none. The longitudinal extent of this great chain is immense, running as far north-west as sixty degrees north latitude, and perhaps to the Frozen Ocean itself. The snows and fountains of this enormous range, from the thirty-eighth to the forty-eighth degree of northern latitude, feed, with never-failing supplies, the Missouri and its powerful auxiliary streams. Illustration: Table lands at the foot of the Rocky Mountains. In endeavoring to explore these Alpine heights, and the sources of the Red and Arkansaw rivers, Captain Pike and his party were bewildered amidst snows, and torrents, and precipices. The cold was so intense, that several of the party had their limbs frostbitten, and were obliged to be abandoned to their fate, by Pike and his surviving companions. In a lateral ridge, separating the valley of the Arkansaw from that of the Platte river, in north latitude forty-one degrees, is a remarkable peak, called the _Great White Mountain_; so remarkable, indeed, as to be known to all the savage tribes for hundreds of miles round, and spoken of in terms of admiration by the Spaniards of New Mexico, and which formed the boundary of their knowledge to the north-west. The altitude of this peak was taken on the base of a mile by Pike, and found to be ten thousand five hundred and eighty-one feet above the level of the meadow at its foot; and the height of this latter was estimated at eight thousand feet above the level of the sea; in all, eighteen thousand five hundred and eighty-one feet of absolute elevation; being six thousand feet higher than the peak of Teneriffe, by Humboldt’s measurement; or two thousand eight hundred and ninety-one feet short of that of Chimborazo, admitting the elevation of this last to be twenty-one thousand four hundred and seventy-two feet. Captain Pike and his companions never lost sight of this tremendous peak, unless in a valley, for the space of ten weeks, wandering amongst the mountains. What is the elevation at the sources of the Missouri can only be matter of mere conjecture. The level of the river, where they left their