In my notes on the stones of Stenness (Chapter XIII) I pointed out that the chambered Cairns at Onston and Maeshowe suggested that such structures were later variants of the more ancient standing stones. Some barrows at the Hurlers lend further confirmation of this view. I will deal with them first. Of one the data are Az. from N. Circle S. 72° 49′ W., height of horizon 12′ (Capt. Henderson). The resulting declination is S. 11° 5′, the declination of Antares 1720 B.C. But why should Antares be thus singled out? The table on page 117 shows the reason. At the date involved the setting of Antares in the dawn was the warner of the sunrise on May morning, the greatest day in all the year. Is there any precedent for this use of Antares? I have already pointed out (p. 108) that Mr. Penrose found the warning stars for May morning at the dates of foundation of the Hecatompedon, and the older Erechtheum, to be the group of the Pleiades rising and _Antares_ setting. As the foundations of the Hecatompedon were built only some few years after the stones of the central circle of the Hurlers were used, we ought to find traces of the observations of the same May-morning stars. We have, then, now a third term in the astronomical use of stars to herald the sunrise on May morning. Temple of Min Thebes 3200 B.C. Spica. Temple at the Hurlers Liskeard 1720 „ Antares. Older Erechtheum Athens 1070 „ „ The next barrow to be referred to--it is shown to be a long one on the Ordnance Map--is situated near the top of Caradon Hill, and is visible on the sky-line from the circles. Data: Az. from N. Circle S. 65° E., height of horizon 1° 38′ (Henderson). This corresponds almost exactly with the azimuth of the rise of the sun’s upper limb with declination S. 16° 20′ on the two critical dates in November and February of the May-year (Halloween and Candlemas, see p. 23), so I am inclined to consider it more than a mere coincidence that the azimuths coincide so closely. It, however, may be urged that there are other barrows on Caradon Hill, but judging from the Ordnance Map they seem to be of the round variety used for burials, perhaps a thousand years after the circles were in use, and in my opinion by a different race of men; but this matter must not detain us now, I hope to return to it later. Still one more barrow and a stone, uncrossed and uninitialled, in the same sight-line, data: Az. from N. circle S. 59° 35′ E. Height of horizon 1° 38′ 23″ (Henderson), resulting declination S. 19° 50′. This was the declination of Sirius 1690 B.C. Why Sirius? The table on p. 117 gives us the answer. Sirius replaced Arcturus as a warning star for the August festival, and we have seen that the last use of Arcturus was connected with the sight-line to the barrow about 1900 B.C.