This present erection was built 1752. Its earlier predecessor was set up 1651 by the Dutch engineer Vermuyden, the maker of the Bedford Rivers, to whose genius the whole present scheme of drainage owes its existence. He carried through his plan in face of most determined opposition, especially from the towns of Lynn and Cambridge, who complained that "whereas of old ships from Newcastle were wont to make eighteen voyages in the year to Cambridge with sea coal, now, since the blocking of the stream at Denver and the diversion of its waters at Earith, they can make but ten or twelve, whereby the price of fuel hath increased by half." When this first sluice was "blown up" by the tide in 1713 there were loud rejoicings. The consequences, however, proved so serious, that the next generation was fain to see it replaced. Lynn is the point to which the road we have been following ultimately leads. On leaving Ely by this road, the first turn to the right will bring us down to the famous Roslyn (or Roswell) Pit, beloved of geologists and botanists. It is a large water-filled excavation by the side of the railway, nurturing various rare water plants, and presenting the wonderful spectacle of chalk lying _above_ boulder-clay, a phenomenon now attributed to ice action.[236] [Footnote 236: See Hughes' _Geography of Cambridgeshire_.] [Illustration: _St. Wendreda's Church, March._] The western declivity of the Island plunges down to the fen at Mepal, on the New Bedford River. After crossing this, the road leads straight across the fen to Chatteris, and is called Ireton's Way; the causeway on which it runs having been made by that great Puritan general, for strategic purposes, during the Civil War. Chatteris was the first of the wonderful chain of Abbeys which swept round the Fenland from Ely into Lincolnshire. The others are Ramsey and Peterborough on the last verge of the mainland; with Thorney and Crowland, rising, like Chatteris, on islands in the morass.[237] Of these, Chatteris and Thorney alone are in Cambridgeshire; though Peterborough is within half a mile of the county boundary. The former, a nunnery, was founded by the Lady Alwyn, foster-mother to Edgar the Peacemaker. It was never a large House, and no remains of it survive; but Chatteris is now the seat of another Benedictine community, exiled from France in 1901. The place possesses some curious wells of warm water, not of any great depth, as such usually are, but penetrating only some ten or twelve feet into the fen deposits. Local chemical decomposition is supposed to account for the phenomenon. The fen hereabouts is rich in geological and archaeological remains. And within sight of his mother's convent, only six miles away across the fen, her son (also an Alwyn), the Alderman or Earl of the district, founded, on the projecting cape of the Huntingdonshire mainland, the much larger abbey of Ramsey, whose abbot was one of the higher or "mitred" class, privileged to