Probably the value of the land on the margin of the rivers, was an additional motive for the course pursued. The alluvial soil by a river’s side is usually the most fertile portion of a country. The banks of the Tyne and the Eden are peculiarly productive. Without a wall the enemy would have had undisputed possession of the slopes which enjoyed the finest aspect—that to the south—while those on the other side would have been subject to frequent depredation. This consideration is of the more importance, as the lands of the district were given to the soldiers who garrisoned the frontier, as a means of securing their fidelity. [Sidenote: PRUDENCE OF THE ROMANS.] So far from the importance of the natural boundary, the river, being overlooked by the Romans, I am disposed to regard the works on its northern bank as a proof of the value which they set upon it. The natural and the artificial barriers were probably regarded by them as but separate members of one complete fortification. In case of a rush of invasion from the North, the Wall would arrest the attack and the river entirely repel it. The stone and earth works would impede the progress of a foe, however formidable, and give time for the formation of an army on the southern bank of the stream. It was, moreover, ‘political in the Romans,’ as Stukely remarks,[53] 'to leave on the north side of the Wall that huge tract of waterless and dismal moor, a great barren solitude, where in some places you may walk sixty miles endwise, without meeting with a house or tree; to ride is impracticable. Thus, as much as in them lay, without the horror of barbarity, did they remove the barbarians from their territories; whilst within the Wall, either naturally or by their industry, all things smiled like the garden of Eden.' The vast hosts which the Caledonians were able to muster rendered all these precautions necessary; and it was, moreover, becoming in the Romans—a generation of warriors the mightiest the world has ever seen—to plant the foot firmly on any land they thought fit to occupy. Assuredly they did so in the Lower Isthmus of Britain. [Illustration: Written Rock, at Fallow-field.] ----- Footnote 14: Hodgson states the mean of nineteen measurements to be one hundred and twenty six yards.—_Northumberland_, II. iii. 310. This high number is obtained by its including the mountain districts, where the works are widely separated. Footnote 15: Harl. MSS. 374,—impr. Hodg. North’d. II. iii. 273. Footnote 16: Harl. MSS. 373,—impr. Richardson’s Reprints and Imprints, divis. Miscell. Footnote 17: It will be observed here that the erection of this structure has not been _always_ ascribed to Severus. Footnote 18: