The illustration represents, in the foreground, the remains of the walls of the city. They were originally of great strength, and formed a triple defence, like those of Constantinople. Two no longer exist, but the inner still stands, with many of its bastions and circular towers. Beyond is the present city, displaying the evidence of a populous town. The bristling minarets and swelling domes indicate a numerous Moslem population, said to amount to 15,000 persons. In the background are the ridges of Mount Tmolus. [Illustration: T. Allom. E. Challis. PASS IN THE BALKAN MOUNTAINS ON THE BULGARIAN SIDE.] The chain of the Balkans generally consists of three parallel ridges, having valleys of exceeding beauty between them. But in some places on the north side, the lower ridge seems obliterated; the descent is very precipitous, and the face of the mountain, like a vast wall, descends almost perpendicularly to the plain below, uninterrupted by any lesser eminence. This is particularly the case with the pass by Philippopoli and Tatar Bazaar. When the traveller stands upon the summit-ridge, he sees the plain of Bulgaria below him, extending its horizontal surface to the Danube, like the sea, to what seems to him an interminable distance. The roads down this side are not only steep, but dangerous, and frequent accidents happen to travellers from the abrupt and sudden descent of the pass. Winding down the narrow defiles on a rugged path, scarcely broad enough for one to pass; when two meet going in an opposite direction, the peril is awful. Neither can go back or turn aside, and one is often precipitated into the gulf below. This danger is increased, and more frequently occurs, from trains of horses laden with iron, the produce of mines found in the recesses of the mountains. The horses travel in a single file, and bound to each other by cords. When one falls over the edge of the precipice, he is generally supported by the rest of the train, till he regains his path and footing. This precaution is taken by other travellers, but baggage horses, from the greater weight and more unmanageable burdens, very often are precipitated over the edge, and disappear into the gulf below, where they are suffered to lie, without any fruitless attempt to follow or regain the baggage. To obviate such accidents, the Surrogee, or Tartar janissary who attends the traveller, stops at the entrance of a dangerous pass, and, drawing his pistols, discharges them into it several times, waiting for some space for a reply. If one is returned in the same manner, it intimates that the defile is already occupied by others, and the party wait their issuing forth. If no return be made to the discharges, they pass on.