The second avenue has its sighting stone built into a wall at the south end. Looking south along the avenue, the conditions are azimuth S. 8° 42′ W., hills 3° 30′.
Both these avenues are aligned on points within, but not at the centre of, the circle.
Challacombe (lat. 50° 36′).—This is a case of a triple avenue, probably the remains of eight rows, in a depression between two hills, Challacombe Down and Warrington. There is no circle. The azimuth is 23° 37′ N.W. or S.E., according to direction. The northern end has been destroyed by an old stream work; there is no blocking stone to the south on either of the remaining avenues, but one large menhir terminates one row of stones. The others may have been removed. So it is probable that the alignment was to the north. If so, we are dealing with the setting of Arcturus, warning the summer solstice sunrise in 1860 B.C. To the S. the hills are 4° 48′, to the N. 4° 50′.
To this result some importance must be attached, first, because it brings us into presence of the cult of the solstitial year, secondly, because it shows us that the system most in vogue in Brittany was introduced in relation to that year. In Brittany, as I have before shown, the complicated alignments, there are 11 parallel rows at Le Ménac ([p. 99]) (there were 8 parallel rows at Challacombe), were set up to watch the May and August sunrises, and the solstitial alignments came afterwards. The Brittany May alignments, therefore, were probably used long before 1860 B.C., the date we have found for Challacombe, where not the sunrise but the setting star which gave warning of it was observed.
Fig. 45.—The remains of the eight rows of the Challacombe Avenue. Looking North of East. Terminal Menhir on the extreme right.
It is worth while to point out that at Challacombe, as elsewhere, the priest-astronomers so located their monuments that the nearly circumpolar stars which were so useful to them should rise over an horizon of some angular height. In this way the direction-lines would be available for a longer period of time, for near the north point the change of azimuth with change in the declination of the star observed is very rapid.
Shovel Down, near Batworthy (lat. 50° 39′ 20″).—A group of five rows of stones, four double, one single, with two sets of azimuths.
One set gives az. 22° 25°, and 28°. They seem to be associated. I will call them A, B, and C. A is directed to the circle on Godleigh Common. Its ends are free. B is a single line of stones to the E. of the triple circle, about which more presently. It is not marked on the Ordnance map; its ends are also free. C has its south end blocked, I think in later times, by a kistvaen. The astronomical direction may be, therefore, either N.W. or S.E. We find a probable use in the N.W. quadrant, as at Challacombe, Arcturus setting at daybreak as a warner of the summer solstice.
The height of hills is 46′; we have then:—