The Carr Dyke—Thurlby—Edenham—Grimsthorpe Castle—King’s Street—Swinstead—Stow Green—Folkingham—Haydor—Silk Willoughby—Rippingale—Billingborough—Horbling—Sempringham and the Gilbertines. Bourne itself is in the fen, just off the Lincolnshire limestone. From it the railways run to all the four points of the compass, but it is only on the west, towards Nottingham, that any cutting was needed. Due north and south runs the old Roman road, keeping just along the eastern edge of the Wold; parallel with it, and never far off, the railway line keeps on the level fen by Billingborough and Sleaford to Lincoln, a distance of five-and-thirty miles, and all the way the whole of the land to the east right up to the coast is one huge tract of flat fenland scored with dykes, with only few roads, but with railways fairly frequent, running in absolute straight lines for miles, and with constant level crossings. One road which goes south from Bourne is interesting because it goes along by the ‘Carr Dyke,’ that great engineering work of the Romans, which served to catch the water from the hills and drain it off so as to prevent the flooding of the fens. Rennie greatly admired it, and adopted the same principle in laying out his great “Catchwater” drain, affectionately spoken of by the men in the fens as ‘the owd Catch.’ The Carr Dyke was a canal fifty-six miles long and fifty feet wide, with broad, flat banks, and connected the Nene at Peterborough with the Witham at Washingborough near Lincoln. From Washingborough southwards to Martin it is difficult to trace, but it is visible at Walcot, thence it passed by Billinghay and north Kyme through Heckington Fen, east of Horbling and Billingborough and the Great Northern Railway line to Bourne. Two miles south of this we come to the best preserved bit of it in the parish of _Thurlby_, or Thoroldby, once a Northman now a Lincolnshire name. The “Bourne Eau” now crosses it and empties into the River Glen, which itself joins the Welland at Stamford. [Sidenote: THURLBY]