(3) Our survey is thus narrowed to a single point--the existence and alleged position of the fort at Chapel Hill, between Old Kilpatrick and Dunglass, on the banks of the river; and here it should be observed as between the two extremities of the Wall, east and west, that where it touches the Frith of Forth at Carriden the height of its foundation ranges from about 150 to 200 feet above the level of the sea, and where it approaches the Clyde at Duntocher it is nearly the same--which was probably its terminus. There is scarcely a vestige of it now traceable beyond that, and that it was ever carried farther in reality is a matter of acknowledged uncertainty. But scattered fragments of masonry, as we have seen, and the dimmest indications of a fort deep down in the earth have been discovered or imagined at Chapel Hill to the westward, which seems to be about 50 feet above the level of the Clyde--leaving still a very large margin beyond Professor Geikie's estimate; and a great deal of conjecture about what might, or might not have been there, has been indulged in by antiquarians. For the present, however, until proof to the contrary has been shown, let us accept as a fact that some military station had really been established there in connection with the Wall--then, how have its fragments been so widely scattered? how has it been so completely entombed that it can only be guessed at under the soil? and how has the connection between it and the Wall, more than two miles distant, been obliterated? No other fort on the line, that we know of, is now in the same condition; and therefore, we repeat, either the Romans were foolishly contending with the tide, by building too close to its confines, and the tide drove them back and overthrew their works; or the fort itself was originally on a higher level, and the shock of an earthquake, or a landslip from the mountains, or both together, carried the whole mass of masonry and earthwork at this particular point down to their present level, where they would be washed by the tide and silted up in their own ruins. This is a view of the matter, indeed, which no antiquarian, so far as we are aware, has hitherto adopted; but any one who chooses to look with an unprejudiced eye, for a moment, at the enormous gap in the hills immediately behind, reaching down to the shore and including this very region, must be satisfied that the case was so; and recent discoveries--one of a quay-wall or foundation of a bridge at Old Kilpatrick, about 4 feet deep in a field; and another of a causeway, more than 20 feet submerged and silted up under sea-sand, on the same side of the river, near Glasgow, will most probably confirm it.