The fact is that the whole descent of the river throughout this portion does not exceed twenty feet, and where it issues from the outliers of the Carpathians the banks slope more gently than higher up, and the summits are simply high hills.  The ‘Iron Gates’ themselves consist of innumerable rocks in the bed of the river.  Here and there they appear above the surface, but generally they are a little below it, and they break up the whole surface for a considerable distance into waves and eddies, through which only narrow passages admit of navigation, insomuch that in certain states of the river the passengers and cargoes of the large steamers have to be transferred to smaller boats above, and retransferred to the larger class of steamers below, the ‘Iron Gates.’

II.

But by far the most distinctive, and for us the most interesting, features of the Danube about here, are its historical reminiscences.  Almost the whole way from Golubatz (Rom.  Cuppae) to Orsova, there are traces on the right (southern) bank of the remarkable road constructed by Trajan (and probably his predecessors) for his expedition into Dacia, and at one place opposite to Gradina is a noted tablet inserted in the rock to commemorate the completion of the road.  This tablet has been the subject of much controversy, and it bears the following inscription:—­

     IMP.  CAESAR.  DIVI.  NERVAE.  F. NERVA.  TRAJANUS.  AUG.  GERM.  PONTIE. 
     MAXIMUS.  TRIB.  POT.  IIII.  PATER.  PATRIAE.[20]

The Servian peasants, however, have little respect for heroes—­at least, for ancient ones—­and the barbarians of seventeen or eighteen centuries appear to have lighted their fires and cooked their ’mamaliga’[21] against the tablet until it presents the appearance of a blackened mass.  Of the road itself we shall speak hereafter at some length in connection with Trajan’s expedition, but a few words concerning his bridge at Turnu-Severin may still be added.  All that remains visible to the traveller to-day are the two terminal piers, of which sketches are here given; but between those piers the bridge spanned the river, and a very low state of the water discloses the tops of several other piers still standing.  In speaking of one bridge we have taken rather a liberty with the facts, for it is now pretty generally admitted that there were really two structures.  Further down the river is a small island which, in former times, is said to have extended to where the remains of the bridge are found, and upon this tongue of land the ends of the sections starting from either shore rested.  The land is supposed either to have sunk or to have been washed away by the current.[22] The bridge, to which further reference will be made in our historical sketch, was built after the plans of Apollodorus, the architect of Trajan’s Column at Rome.  It was commenced about 103 A.D., and probably consisted of twenty piers,