[Illustration: FIG. 39.--Copy of Ordnance Map showing chief sight-lines from the stones of Stenness.] I shall not refer to all the sight-lines indicated, but deal only with those which I have without local knowledge been able to test and justify by means of the 25-inch Ordnance map. Not only does calculation prove the worship of the May and June years, but I think the facts now before us really go to show that in Orkney the May year was the first established, and that the solstitial (June) year came afterwards, and this was one of the chief questions I had in view. I will begin with the May year. I have already shown, p. 22, that the half-way time between an equinox and a solstice is when the sun’s centre has a declination approximately 16° 20′ N. or S. In Orkney, with the latitude of 59°, assuming a sea horizon, the approximate amplitude of sunrise or sunset is 33° 6′, the corresponding azimuth being 56° 54′. Now the most interesting and best defined line near this azimuth on the Ordnance map is the one stretching S.E. from the centre of the Stenness circle to the Barnstone, with an azimuth of 57° 15′. The line contains between the two points I have named another stone, the Watchstone, 18¹⁄₂ feet high, in the precise alignment; and from the statements made and measures given it is to be inferred that a still more famous and perforated stone, the “Stone of Odin,” demolished seventy years since, was also in the same line within the extremities named. If we may accept this we learn something about perforated stones, and can understand most of the folk lore associated with them, and few have more connected with them than the one at Stenness. I suggest that the perforation, which was in this case 5 feet from the ground, was used by the astronomer-priest to view the sunrise in November over the Barnhouse stone in one direction, and the sunset in May over the circle in the other. I hope to be able to return to this question subsequently. There is another echo of this fundamental line; that joining the Ring of Bookan and the Stones of Via has the same azimuth and doubtless served the same purpose for the May year. But this line, giving us the May sunset and November sunrise, _not_ the December solstitial sunrise as Mr. Spence shows it, is not the only orientation connected with the May year at the stones of Stenness. The November sunset is provided for by a sight-line from the circle to a stone across the Loch of Stenness with an azimuth of S. 53° 30′ W. To apply the table, given on p. 120, to the solstitial risings and settings at Stenness, and the sight-lines which I have plotted on the map, it will be seen that the table shows us that the lines marked S. 41° 0′ E. N. 41° 16′ E. S. 36° 30′ W. are solstitial lines; to get exact agreement with the table the heights of the hills must be found and allowed for.