The great main range of chalk which runs all across south-eastern England; the range whose escarpment affords for sixty miles a platform for the Old Road is broken, then, by the Medway, which cuts through it on its way to the sea. But there is not only a gap; it will be seen that the hills 'bend up,' as it were, upon either bank, and follow the stream northward, making a kind of funnel to receive it. The effect of this is best expressed by saying, that it is as though the Medway valley had been scooped out by a huge plough, which not only cut a five-mile gap in the range, but threw the detritus of such a cutting to left and right for miles beyond the point of its passage. It is at the mouth of this gap that the two shoulders or turning-places are to be found; one on the west at Wrotham, the other on the east at Grey Wethers: while beyond them the Downs turn northward either way, to sink at last into the flats of the Thames estuary. The interval between these 'shoulders' was the most considerable of any that had to be filled in all our exploration. The reason that this gap in the Old Road should be found at such a place was evident. It was here that the road had to cross the most important of the rivers it meets upon its course, the Medway. Alone of the rivers which obstruct the road, it is a tidal stream, and, as though in recognition of its superior claim, the hills receded from it more grandly than they had from the Wey at the Guildford, or the Mole at the Dorking passage. They left six miles of doubtful valley between them, and across these six miles a track had to be found. [Illustration: THE MOST IMPORTANT OF THE RIVERS IT MEETS UPON ITS COURSE, THE MEDWAY] A clear statement of the problem will lead one towards its solution. I have said that for several miles before Wrotham, the chalk hills, well defined and steep, running almost due east and west, present an excellent dry and sunny bank for the road. As one goes along this part of one's journey, Wrotham Hill appears like a kind of cape before one, because beyond it the hills turn round northward, and their continuation is hidden. I have also told how, a long way off, over the broad flat of the Medway valley, the range may be seen continuing in the direction of Canterbury, and affording, when once the river is crossed, a similar platform to that from which one is gazing. We knew, also, that the road does, as a fact, follow those distant hills, precisely as it had the range from which we made our observation, and if no physical obstacles intervened, the first travellers upon this track would undoubtedly have made a direct line from the projecting shoulder of Wrotham Hill to the somewhat less conspicuous turning-point which marks the further hills of Grey Wethers, where also Boxley once stood.