The facts I have discovered, which lead up to the conclusions, can be verified for the most part on an inch to mile ordnance map with aid of a straight edge.
Taking all the earthworks mentioned, add to them all ancient churches, all moats and ponds, all castles (even castle farms), all wayside crosses, all cross roads or junctions which bear a place name, all ancient stones bearing a name, all traditional trees (such as gospel oaks), marked on maps, and all legendary wells. Make a small ring round each on a map. Stick a steel pin on the site of an undoubted sighting point, place a straight edge against it, and move it round until several (not less than four) of the objects named and marked come exactly in line.
You will then find on that line fragments here and there of ancient roads and footpaths, also small bits of modem roads conforming to it. Extend the line into adjoining maps, and you will find new sighting points on it, and it will usually terminate at both ends in a natural hill or mountain peak, or sometimes (in the later examples) in a legendary well or other objective.
If you travel along the actual sighting line you will find fragments of the road showing as a straight trench in untilled land,
although these are few and far between, as the plough obliterates it all. The line usually crosses a river at a known ford or ferry. Sighting tumps not marked on the map are also to be found.
Two specific proofs are illustrated in Plate IV and explained in the Table of Illustrations. Also from the highest point of the earthworks of Dinedor Camp the spire of All Saints' Church can be seen precisely between the pinnacles of Hereford Cathedral, thus showing a sighting tump and two churches on one ley. The Offa Street example (see under Churches) is another three-point proof.