The Romans, when they made the artificial canal, the Carsdike, from Peterborough along the edge of the Lincolnshire fens, introduced it into the river Witham, three miles below Lincoln. The purpose of this artificial cut was, to convey corn in boats, from the southern parts of England, to the northern _prætentura_’s in Scotland for maintenance of the forces kept there: therefore the canal, entering the Witham, passed through Lincoln, and then was continued by another artificial cut, called the Fossdike, from Lincoln to Torksey, where it enters the Trent, in order to go down the stream to the Humber: from thence the fleet of corn-boats passed up the river Ouse to York, by force of the tide; for so high will the tide carry them; which was the reason of building the city there. After this Fossdike, between the Trent and Witham rivers, was made by the Romans, it is easy to imagine, that the extensive river of Trent, which runs altogether northwards, would very readily, upon great floods, discharge part thereof into the Fossdike; for there is a descent that way, as being to the east: and this might be the occasion of the geography in our map, mistaking the Fossdike, and the continuation of the Witham, for that of the Trent. The river Witham, from Lincoln, goes south-east into the sea, by Boston; and it seems to me, that in very early times it might (at least in great floods) have another channel running over the East fen (as called) along that natural declivity, full east, into the sea, as in the map of Richard of Cirencester. This channel might pass out of the present river of Witham a little below Coningsby, where the river Bane falls into it, at Dockdike and Youldale, by the water of Hobridge, north of Hundle-house; so running below Middleholm to Blacksike, it took the present division between the two wapentakes, all along the south sides of the deeps of the East fen; and so by Blackgote to Wainfleet, the +Vainona+ of the Romans. My friend, John Warburton, Esq; Somerset herald, has some manuscripts of our Lincolnshire antiquary, some years ago, Mr. De la Pryme, who was perfectly acquainted with that part of Lincolnshire, and therein discovers some suspicions of the Trent running toward Lincoln in antient days; but I think, all we can certainly conclude from our map is the extreme antiquity of it: as the Carsdike must have been projected and done by Agricola, on his conquest of Scotland, we may reasonably judge this to be in the main his map, i.e. copied from his, though with some additions by our author. This consideration, duly attended to, shows the antiquity of the Fossdike, and Carsdike, and of our map.