In the south-eastern corner of European Russia, between the Black Sea and the Caspian, in about the latitude of New York City, there rises abruptly from the dead level of the Tatar steppes a huge broken wall of snowy alpine mountains which has been known to the world for more than two thousand years as the great range of the Caucasus. It is in some respects one of the most remarkable mountain-masses on the globe. Its peaks outrank those of Switzerland both in height and in rugged grandeur of outline; its glaciers, ice-falls and avalanches are second in extent and magnitude only to those of the Himalayas: the diversity of its climates is only paralleled by the diversity of the races which inhabit it; and its history--beginning with the Argonautic expedition and ending with the Russian conquest--is more romantic and eventful than that of any other mountain-range in the world. Geographically, the Caucasus forms a boundary-line between South-eastern Europe and Western Asia, but it is not simply a geographical boundary, marked on the map with a red line and having no other existence: it is a huge natural barrier seven hundred miles in length and ten thousand feet in average height, across which, in the course of unnumbered centuries, man has never been able to find more than two practicable passes, the Gorge of Dariel and the Iron Gate of Derbend. Beginning at the Straits of Kertch, opposite the Crimea on the Black Sea, the range trends in a south-easterly direction across the whole Caucasian isthmus, terminating on the coast of the Caspian near the half-Russian, half-Persian city of Baku. Its entire length, measured along the crest of the central ridge, does not probably exceed seven hundred miles, but for that distance it is literally one unbroken wall of rock, never falling below eight thousand feet, and rising in places to heights of sixteen and eighteen thousand, crowned with glaciers and eternal snow. No other country which I have ever seen presents in an equally limited area such diversities of climate, scenery and vegetation as does the isthmus of the Caucasus. On the northern side of its white jagged backbone lies the barren wandering-ground of the Nogai Tatars--illimitable steppes, where for hundreds of miles the weary eye sees in summer only a parched waste of dry steppe-grass, and in winter an ocean of snow, dotted here and there by the herds and the black tents of nomadic Mongols. But cross the range from north to south and the whole face of Nature is changed. From a boundless steppe you come suddenly into a series of shallow fertile valleys blossoming with flowers, green with vine-tangled forests, sunny and warm as the south of France. Sheltered by its rampart of mountains from the cold northern winds, vegetation here assumes an almost tropical luxuriance. Prunes, figs, olives and pomegranates grow almost without cultivation in the open air; the magnificent forests of elm, oak, laurel,