IV. In adducing this evidence--partly antiquarian and partly geological--we have restricted our survey exclusively to the Roman Wall, for it is on this important barrier between the Forth and Clyde that those who object to the geography of Ossian are accustomed to fall back. But the sort of testimony it affords might be easily supplemented by a survey of the Clyde itself, which can be shown, and has been shown, by incontestable measurement on the coast of Ayrshire, to be sinking at the rate of ¾ of an inch annually for the last forty or fifty years at least; and if such subsidence has been going on for fifteen hundred years at the same rate, the level of the frith in the days of the Romans must have been even higher than we now allege. A critic in the _Scotsman_, who, himself, first demanded such a survey, and to whom the survey when reported in the same paper--August 30th, 1875--was troublesome, appeals boldly in an editorial note to the authority of Hugh Miller, and again demands that the survey be transferred from Girvan to Glasgow, because "the height to which the tide rises is a very fluctuating quantity"--in Ayrshire, we presume. As for Hugh Miller, we can find nothing whatever in his pages to the purpose; and if such a distinguished authority is to be relied on in the present controversy, we must insist on his very words being quoted. As for the fluctuation of the tide, if it fluctuates in one place more than another, what is the use of appealing to it at all? and as between the Ayrshire coast, and the Renfrewshire or Lanarkshire coast, on the same side of the frith, unless "the moon and one darn'd thing or another" have special disturbing influence in Ayrshire, what difference can there be in the regularity of flow between Girvan and Glasgow? This learned adversary in the _Scotsman_ must surely have been at his wit's end when he took refuge in such an absurdity, and we may safely leave him where he is, to revise his own calculations and recover his composure.