On a fine morning in early autumn of the year 1771, Kien Long, the Emperor of China, was pursuing his amusements in a wild frontier district lying on the outside of the Great Wall. For many hundred square leagues the country was desolate of inhabitants, but rich in woods of ancient growth, and overrun with game of every description. In a central spot of this solitary region, the Emperor had built a gorgeous hunting-lodge, to which he resorted annually for recreation and relief from the cares of government. Led onwards in pursuit of game, he had rambled to a distance of two hundred miles or more from this lodge, followed at a little distance by a sufficient military escort, and every night pitching his tent in a different situation, until at length he had arrived on the very margin of the vast central deserts of Asia. [Footnote: All the circumstances are learned from a long state paper upon the subject of this Kalmuck migration, drawn up in the Chinese language by the Emperor himself. Parts of this paper have been translated by the Jesuit missionaries. The Emperor states the whole motives of his conduct and the chief incidents at great length.] Here he was standing, by accident, at an opening of his pavilion, enjoying the morning sunshine, when suddenly to the westward there arose a vast cloudy vapor, which by degrees expanded, mounted, and seemed to be slowly diffusing itself over the whole face of the heavens. By-and-by this vast sheet of mist began to thicken towards the horizon, and to roll forward in billowy volumes. The Emperor's suite assembled from all quarters. The silver trumpets were sounded in the rear, and from all the glades and forest avenues began to trot forward towards the pavilion the yagers, half cavalry, half huntsmen, who composed the Imperial escort. Conjecture was on the stretch to divine the cause of this phenomenon, and the interest continually increased, in proportion as simple curiosity gradually deepened into the anxiety of uncertain danger. At first it had been imagined that some vast troops of deer, or other wild animals of the chase, had been disturbed in their forest haunts by the Emperor's movements, or possibly by wild beasts prowling for prey, and might be fetching a compass by way of re- entering the forest grounds at some remoter points secure from molestation. But this conjecture was dissipated by the slow increase of the cloud, and the steadiness of its motion. In the course of two hours the vast phenomenon had advanced to a point which was judged to be within five miles of the spectators, though all calculations of distance were difficult, and often fallacious, when applied to the endless expanses of the Tartar deserts. Through the next hour, during which the gentle morning breeze had a little freshened, the dusty vapor had developed itself far and wide into the appearance of huge aerial draperies, hanging in mighty volumes from the sky to the earth; and at