The works of the Barrier are crossed by the railway a little to the west of Rose-hill station. The Wall here exhibits three or four courses of facing-stones. A little beyond this point, the lines, still clearly defined, cross the stream called Poltross-burn, which divides the counties of Northumberland and Cumberland. The gorge in which the stream flows is deep and well-wooded. There are no remains of a bridge in the valley, but traces of a mile-castle, by which the defile has been guarded, are distinct upon its western bank. Before reaching the Irthing, at a farm-house called Willowford, the site of another castellum may be discerned. From this point to the water’s edge, the Wall and Vallum have probably gone in close companionship; but this is a matter which cannot now be ascertained. The western bank of the river is lofty and precipitous. Consisting, as it does, chiefly of diluvial soil and gravel, on which the water of the stream below is continually acting, it is not surprising that all traces of the Wall, if it ever ascended the height, have long since disappeared. On the very brink of the precipice above, the remains of the Wall and fosse re-appear. The faithful followers of the Wall, who have closely pursued its track from the eastern sea, will not be willing to desert their companion, even for a brief space, at this point. The cliff, however, will test their constancy. Hutton had his troubles; he says, somewhat magniloquently— [Sidenote: PASSAGE OF THE IRTHING.] I had this river to cross, and this mountain to ascend, but I did not know how to perform either. I effected a passage over the river by the assistance of stones as large as myself, sometimes in and sometimes out; but, with difficulty, reached the summit of the precipice by a zig-zag line, through the brambles, with a few scratches. The latest historian of the Wall attempted to ascend the bank in a right line; he has given us the result of his experience, as a warning to others. None of the party completely succeeded in ascending the precipitous bank by the course of the Wall. The attempt is very dangerous, and, as success accomplishes nothing, should never be tried by those whose life and existence are in any way useful. On the top of the cliff is a mile-castle. To the north, two conical summits appear, which strongly resemble barrows. We now approach Birdoswald, the twelfth station on the line. [Sidenote: AMBOGLANNA.] AMBOGLANNA, the Birdoswald of the present day, is an interesting station. [Illustration: alt=Altar to Jupiter, by Coh. I. Ael. Dac.] Numerous inscriptions have been found within its walls, mentioning the first cohort of the Dacians, surnamed the Ælian, which, according to the Notitia, was quartered at AMBOGLANNA. One of them, in the possession of Robert Bell, esq., of the Nook, Irthington, is here figured.