each 150 Roman feet high and 60 feet broad, and the distance between the two terminal piers on the banks is about 3,900 English feet.  The piers were of stone, but the upper part of the bridge was wood.  In the northern pier the stone consists of rubble, or artificial conglomerate composed of small roundish stones and cement, and this was probably cast into blocks, but the one on the right (southern) bank is of hewn stone.  On the northern side there is an old wall running up from the pier to the ruins of a tower which was evidently connected with the bridge.

[Illustration:  TERMINAL PIER ON SERVIAN SIDE. (FROM A SKETCH BY THE AUTHOR.)]

But it would be better that we should reserve any further remarks concerning the archaeological relics of Roumania, and also some observations of immediate interest in connection with the Danube, until we have completed a brief account of the water system of the country.

Between the ‘Iron Gates’ and its three embouchures, namely, the Khilia, Sulina, and St. George’s mouths, of which only the second is navigable by large vessels, the Danube stretches fora distance of about 650 miles,[23] and receives in its course numerous tributaries, whereof the following are the principal on the Roumanian side.  The Pruth is the most important.  It forms the boundary between Roumania and Bessarabia (Russia), and is navigable by small grain-carrying vessels.  Next in importance historically is the Sereth, which divided Moldavia from Wallachia, and the remaining rivers of any moment are the Oltu, on which are situated the towns of Rimnic and Slatina; the Jalomitza, watering Tirgovistea, one of the ancient capitals, and receiving as an affluent the Prahova, which takes its rise near Sinaia.  The last-named is a very interesting river, for in the vicinity of either bank are to be found the petroleum wells or salt mines.  Then there is the Ardges, which flows past the little city of the same name and the town of Pitesti, and receives the Dambovitza, on which the capital, Bucarest, is situated.  In these rivers are to be found in their due seasons many species of fish, and as fishing is but little preserved they furnish good sport.  The most important kinds used for the table in Roumania are two or three varieties of sturgeon, trout (small but sweet), herrings, salmon, shad, pike, and carp, also perch, roach, barbel, tench, &c.  Roumania is not a lake country, and the largest lakes, called Baltas, are found in the plains near the Danube, whilst amongst the inland lakes, which are few in number and importance, that of Balta Alba, in the district of Romnicu Sarat, possesses strong mineral properties, in which chloride of sodium and carbonate and sulphate of soda preponderate.  Its waters are used for baths, and are said to cure certain forms of scrofula, rheumatism, neuralgia, and other germane maladies.  Besides Balta Alba, Roumania possesses several other sources of mineral waters.