April 6, 1905] 



NA TURE 



535 



NOTES ON STONEHENGE.' 



\. — On the Star Observ-ations made in British 

 Stone Circles. - 



' I' HE work I have tried to do so far on our British 



* stone circles has dealt with the observations of 

 the sun made in connection with them, and the 

 attempt to determine a date has been based upon the 

 slow change in the obliquity of the ecliptic which is 

 continually taking place. 



In continuation of my work in Egypt in iSgi, and 

 Mr. Penrose's in Greece in 1S92, I have recently 

 endeavoured to see whether there are any traces in 

 Britain of the star observations which I found con- 

 nected with the worship of the sun at certain times 

 of the year. We both discovered that stars, far out of 

 the sun's course, espesially in Egypt, were observed in 

 the dawn as heralds of sunrise — " warning-stars " — so 

 that the priests might have time to prepare the sunrise 

 sacrifice. To do this properly the star should rise 

 while the sun is still about 10° below the horizon. 



I stated (" Dawn of .Astronomy," p. 319) that Spica 

 was the star the heliacal rising of which heralded 

 the sun on May-day 3200 B.C. in the temple of Min 

 at Thebes. Sirius was associated with the summer 

 solstice at about the same time. The equinoxes were 

 provided for in the same way in Lower Egypt, but 

 they do not concern us now. 



Mr. Penrose found this May-day worship continued 

 at Athens on foundations built in 1495 B.C. and 

 2020 B.C., on which the Hecatompedon and older 

 Erechtheum respectively were subsequentlv built, the 

 warning star being now no longer Spica, but the 

 cluster of the Pleiades. 



It is generally known that Stonehenge is associated 

 with the solstitial year, and I have recently suggested 

 that it was originally connected with the May year ; 

 but the probable date of its re-dedication, 1680 B.C., 

 was determined by Mr. Penrose and myself by the 

 change of obliquity. 



Now if Stonehenge or any other British stone circle 

 could be proved to have used observations of warn- 

 ing stars, the determination of the date when such 

 observations were made would be enormously facili- 

 tated. Mr. Penrose and myself were content to think 

 that our date might be within 200 years of the truth, 

 whereas if we could use the rapid movement of 

 stars in declination brought about bv the precession 

 of the equinoxes, instead of the slow change of the 

 sun's declination brought about bv the change of the 

 value of the obliquity, a possible error of 200 years 

 would be reduced to one of 10 years. 



In spite of this enormous advantage, so far as I 

 know no one has yet made any inquiry to connect 

 star observations with any of the British circles. 



I have recently obtained clear evidence that some 

 circles in different parts of Britain were related to 

 the May year, a vegetation year, which we know w^as 

 gerieral over the whole of Europe in early times, and 

 which still determines the quarter-days in Scotland. 



If the Egyptian and Greek practice were continued 

 here, we should expect to find some indications of 

 the star observations utilised at the temple of Min and 

 at the Hecatompedon for the beginning or the other 

 chief months of the May year. 



Following the clue given me in the case of the 

 Egyptian temples, such as Luxor, by successive small 

 changes of the axis necessitated by the change in 

 a star's place due to precession. I have looked out for 

 this peculiarity in an examination of many maps and 

 plans of circles. 



I have already come across two examples in which 



P ' Continued from p. 39^. 



^ - This article is generally based upon a note communicated to the Royal 



Society on March 15. 



NO. 1849, VOL. 71] 



the sight line has been changed in the Egyptian 

 manner. The first is the three circles of the Hurlers, 

 near Liskeard, a plan of which is given in " Pre- 

 historic Stone Monuments of the British Isles : Corn- 

 wall," by H. C. Lukis, published bv the Societv of 

 Antiquaries, who were so good as to furnish me with 

 a copy, and also some unfolded plans on which sight 

 lines could be accurately drawn and their azimuths 

 determined. I am anxious to express my obligations 

 to the council and officers of the society for the help 

 thus afforded me. 



The second is at Stanton Drew, in Somerset, con- 

 sisting of three circles, two avenues, and at least one 

 outstanding stone. These were most carefully sur- 

 veyed by Mr. C. E. Dymond some years ago, and 

 he was good enough to send me copies of his plans 

 and levelling sections. 



How can such plans help us? The easiest way for 

 the astronomer-priests to conduct such observations in 

 a stone circle would be to erect a stone or barrow 

 indicating the direction of the place on the horizon 

 at which the star would rise. If the dawn the star 

 was to herald occurred in the summer, the stone or 

 barrow itself might be visible if not too far away, 

 but there was a reason w'hy the stone or barrow 

 should not be too close ; in a solemn ceremonial the 

 less seen of the machinery the better. 



Doubtless such outstanding stones and barrows 

 would be rendered obvious by a light placed on or 

 near them. Cups which could hold oil or grease are 

 known in connection with such stones, and a light 

 thus fed would suffice in the open if there were no 

 wind ; but in windy weather a cromlech or some 

 similar shelter must have been provided for it. 



Now if these standing stones or barrows were ever 

 erected and still remain, accurate plans — not the 

 slovenly plans with which Ferguson and too many 

 others have provided us, giving us either no indica- 

 tion of the north or any other point, or else a rough 

 compass bearing w-ithout taking the trouble to state 

 the variation at the time and place — will help us in 

 this way. 



The work of Stockwell in America, Danckworth in 

 Germany, and Dr. W. J. S. Lockyer in England has 

 provided us with tables of the changing declinations 

 of stars throughout past time, or enough of it for our 

 purpose. 



An accurate determination of either the azimuth 

 (angular distance from the N. or S. points) or ampli- 

 tude (angular distance from the E. or W. points) of 

 the stone or barrow as seen from the centre of the stone 

 circle will enable us to determine this declination. 



This, of course, only gives us a first approximation. 

 The angular height of the point on the horizon to 

 which the alignment or sight-line is directed by the 

 stone or barrow from the centre of the circle must 

 be most accuratelv determined, otherwise the declin- 

 ations may be one or two degrees out. 



To come back to the two cases to which I have 

 referred, the Hurlers and Stanton Drew. I will begin 

 with a reference to the available descriptions of the 

 circles. 



The three circles of the Hurlers, some five miles 

 to the north of Liskeard, are thus referred to by 

 Lukis in the valuable monograph which I have 

 alreadv mentioned. 



" On the moor, about a mile to the south of the 

 singular pile of granite slabs, w'hich rest upon and 

 overlap each other, and is vulgarly called the 

 Cheesewring, there are three large circles of granite 

 stones placed in a nearly straight line in a north- 

 north-east, and south-south-west direction, of which 

 the middle one is the largest, being 135 feet in 

 diameter, the north no feet, and the south 105 feet. 



" The north Circle is 98 feet, and the south 82 feet 



