Another interesting matter is that the explorers in question were able to trace an ancient stone alignment from the circle to the holed stones.
I have long held that these holed stones were arrangements for determining an alignment. The famous Odin stone at Stenness, long since disappeared, was, if we may trust the very definite statements made about its position, used to observe the Barnstone in one direction and the chief circle in the other.
![[Larger plan]](#5911925350219446446_illo295lg.jpg.id-1326139559946843717.wrap-0.html.html){kind=link}
Fig. 56.—Plan of the Mên-an-tol from Lukis, showing that it was an apparatus for observing the sunrise in May and August in one direction and the sunset in February and November in the other. Sun’s declination, 16° N. or S.
The azimuths suggest that theodolite measures may show that the Tregaseal stones might have been used in the same way; they, the Longstone and Lanyon Quoit, are in nearly the same straight line, the alignment, holed stones to Longstone and Lanyon Quoit, being N. 67° E., so that the May sunrise may have been noted in this way.
Photo. by Lady Lockyer.
Fig. 57.—The Mên-an-tol.
Several other monuments, e.g., Chûn Castle and Cromlech, are to be found in the immediate neighbourhood of the Tregaseal circle and the Longstone, but these will have to await further investigation as to their character and antiquity before any conclusions concerning their astronomical use can be deduced.