Our next point, on leaving St. Ives, is the tiny village of Holywell, which we may reach either by road, through the hamlet of Needingworth, or (preferably) by a field-path running westwards from near the railway station. The little church here stands on a slope above the river, and in the churchyard the holy well is still to be seen. But the delight of the place is its strand along the Ouse, a rarely picturesque medley of old houses on one side of the road and on the other the broad clear stream, here crossed by a ferry. This road continues (as a mere field-path) to another delicious ferry a mile lower, with a charming little inn beside it, in a grove of lofty trees. This lovely spot is named Overcote. Here travellers may cross into Cambridgeshire and make their way along the "Hundred Foot" embankment (so called because it is thirty yards in width) along the river to Earith. For motors the way lies through Needingworth, and past the pretty little Church of Bluntisham, with its three-sided apse and its churchyard yews. Earith is a hamlet of Bluntisham, but a much larger place, owing its importance to its situation on the point where the great works connected with the drainage of the fens have their beginning by the diversion of the Ouse waters from their ancient bed into the two "Bedford Rivers," the Old and the New, which from this point run straight as a die (like the supposed "canals" in Mars) across the fen to Denvers Sluice, twenty-two miles away. The former was made in 1630, the latter in 1650, at the expense of what we should now call a company, promoted by the Earl of Bedford. No such cuts exist elsewhere in the world. Along them a clear horizon is to be obtained, and here, accordingly, was conducted, some forty years ago, a decisive experiment for proving the sphericity of the earth.