[Footnote 285: The very latest spade-work on the Wall (undertaken by Messrs. Haverfield and Bosanquet in 1901) shows that the original wall and ditch ran through the midst of the great fortresses of Chesters and Birdoswald, which are now astride, so to speak, of the Wall; pointing to the conclusion that Severus rebuilt and enlarged them. In various places along the Wall itself the stones bear traces of mortar on their exterior face, showing that they have been used in some earlier work.] [Footnote 286: This is the number _per lineam valli_ given in the 'Notitia.' Only twelve have been certainly identified. They are commonly known as "stations."] [Footnote 287: Antiquaries have given these structures the name of "mile-castles." They are usually some fifty feet square.] [Footnote 288: The familiar name of "Wallsend" coals reminds us of this connection between the Tynemouth colliery district and the Wall's end.] [Footnote 289: So puzzling is the situation that high authorities on the subject are found to contend that the work was perfunctorily thrown up, in obedience to mistaken orders issued by the departmental stupidity of the Roman War Office, that in reality it was never either needed or used, and was obsolete from the very outset. But this suggestion can scarcely be taken as more than an elaborate confession of inability to solve the _nodus_.] [Footnote 290: It should be noted that the "Vallum" is no regular Roman _muris caespitius_ like the Rampart of Antoninus, though traces have been found here and there along the line of some intention to construct such a work (see 'Antiquary,' 1899, p. 71).] [Footnote 291: In more than one place the line of fortification swerves from its course to sweep round a station.] [Footnote 292: Near Cilurnum the fosse was used as a receptacle for shooting the rubbish of the station, and contains Roman pottery of quite early date.] [Footnote 293: See p. 233.] [Footnote 294: See p. 232.] [Footnote 295: The existing military road along the line of the Wall does not follow the track of its Roman predecessor. It was constructed after the rebellion of 1745, when the Scots were able to invade England by Carlisle before our very superior forces at Newcastle could get across the pathless waste between to intercept them.]