Mr. Worth’s survey gives another line of stones. It is undoubtedly, I think, an ancient line, although it is not shown in the Ordnance map, a clear indication of the difficulty of discriminating these avenues on land cumbered with stones in all directions. Its azimuth is N. 24° 25′ E., and the height of the horizon 5° 10′. This gives us Arcturus at the date 1860 B.C., showing that, as at the Hurlers, Arcturus was used as a clock-star. Hence a possible astronomical use is evident, while this row, like the others, could have been of no practical use to anybody. It is interesting to note that this single row of stones is older than the double ones; this seems natural.
It is worth while to say a word as to the different treatment of the ends of the south avenue now that it seems probable that it was used to watch the rising of the Pleiades. At the east end there is what archæologists term a “blocking stone”; these observations suggest that it was really a sighting stone. At the west end such a stone is absent, but the final stones in the avenue are longer than the rest. This may help us in the true direction of the sight-lines in other avenues; and, indeed, I shall show in the sequel that this consideration affords a criterion which, in the cases I have come across, is entirely in harmony with others.
[22] On June 15, 1905, that excellent guide of the Chagford part of the moor, Mr. S. Perrott, showed me an avenue (Azimuth N. 20° E. true) near Hurston Ridge which is not given in the 1-inch map.
CHAPTER XVI
THE DARTMOOR AVENUES (continued)
My inquiries began at Merrivale because there is a circle associated with the avenues a little to the south of the west end of the longest; and again nearly, or quite, south of this there is a fine menhir, possibly used to give a north-south line. There is another menhir given on the Ordnance map, azimuth N. 70° 30′ E., which, with hills 3° high, points out roughly the place of sunrise from the circle in May (April 29). Although this stone has been squared and initialed, I think I am justified in claiming it as an ancient monument. There is still another, azimuth N. 83° E., giving a line from the circle almost parallel to the avenue. I hope some local archæologist will examine it, for if ancient it will tell us whether the N. avenue or the circle was built first, a point of which it is difficult to overrate the importance, as it will show the strict relationship between the astronomy of the avenues and that of the circle, and we can now, I think, deal with the astronomical use of circles after the results obtained at Stonehenge, Stenness and the Hurlers as an accepted fact. With the above approximate values the date comes out 1750 B.C., the declination of the Pleiades being N. 6° 35′.
I now pass on from Merrivale as an example of those avenues the direction of which lies somewhere in the E.-W. direction. Others which I have not seen, given by Rowe, are at Assacombe, Drizzlecombe and Trowlesworthy; to these Mr. Worth adds Harter or Har Tor (or Black Tor).
The avenues which lie nearly N. and S. are more numerous. Rowe gives the following:—Fernworthy, Challacombe, Trowlesworthy, Stalldon Moor, Battendon, Hook Lake, and Tristis Rock. Of these I have visited the first two, as well as one on Shovel Down not named by Rowe, and the next two I have studied on the 6-inch Ordnance map.
Fernworthy (lat. 50° 38′).—Here are two avenues, one with azimuth N. 15° 45′ E., hills 1° 15′. There is a sighting stone at the N. end. We appear to be dealing with Arcturus as clock-star 1610 B.C. This is about the date of the erection of the N. avenue at Merrivale.