March 26, 190S] 



NATURE 



487 



NOTES ON ANCIENT BRITISH 

 MONUMENTS.' 



VII. — The Aberdeen Circles (Contintied).- 



IN December, 1906, I gave an account of my 

 measures of four examples of a very special type 

 of circle which is only to be found, so far as I know, 

 in Aberdeenshire. They were described in relation 

 to other circles by Mr. Lewis in his paper on 

 the stone circles of Scotland. My wife and I 

 again went to Aberdeen last autumn and measured 

 another twenty-live, leaving, I believe, still more 

 than a hundred to be examined. 



The survey last year has greatly increased the in- 

 terest in them, and I hope to show that a complete 

 inquiry into them may advance science in many direc- 

 tions, especially if other allied questions are included 

 in the research. 



The instrument employed in the reconnaissance, for 

 time did not allow of a complete survey, was a com- 

 pass clinometer of Barker's pattern, giving azimuths 

 and angular heights of the horizon, say, to half a 

 degree, a reading quite as fine as can be hoped for, 

 considering the rough condition of the monuments, 

 and the presence of trees on the horizon 

 in many cases. .\s I said in my 

 iqo6 notes, observations of the height 

 of the horizon in winter, when the trees 

 are leafless, are very desirable. 



In the observations last year, the 

 orientation was determined by attempt- 

 ing to find the direction of the line 

 across the circle at right angles to the 

 face of the recumbent stone. Last year 

 I worked differently. 



The method of observation adopted 

 was to measure the azimuth of the line 

 Iving along the common N. and S. sur- 

 faces of the supporters and recumbent 

 stone, and in the eastern direction where 

 possible. When there was no common 

 line, supporters and recumbent stone 

 were dealt with separately. In some 

 of the complete and undisturbed triliths 

 the correspondence of the azimuths of 

 both surfaces showed that immense care ^"^■ 

 had been taken in selecting and " plant- 

 ing " the stones. 



The mean of the azimuths thus obtafned, deducting 

 go°, gave the direction of the observing line across 

 the circle. 



In some cases it seemed as if the circle builders had 

 got this line in the first instance by erecting two 

 stones on the opposite side of the circle about the 

 same distance apart as the two supporters — a kind of 

 avenue, the surfaces of the recumbent stone being 

 placed at right angles to this line. 



This premised, I next give a comparison between 

 the Cornwall and .Aberdeen monuments : — 



(i) .Assuming that the recumbent stone in .■Aber- 

 deenshire was used as a directrix, like the outstand- 

 ing stones of the Cornish and Gorsedd circles, 

 all the conclusions 1 arrived at in Cornwall and on 

 Dartmoor are abundantly confirmed. 



(2) I have examined no circle in Aberdeenshire the 

 astronomical use of which, with one or two excep- 

 tions to be referred to later, is not perfectly obvious 

 in the light of former work. 



(3) The directions indicated by the Aberdeen recum- 

 bent or directing stones are generally the same as 

 those indicated by the outstanding stones in Corn- 



1 Continued from p. 416. 



- Nature, vol. Ix.w.. p. 150. 



wall. The exceptions are that the cardinal points N. 

 true and W. true are indicated in the former. 



(4) The N. and the VV. true alignments may indi- 

 cate an advance in astronomical knowledge. The N. 

 alignments suggest that time at night was determined 

 by circumpolar stars. The W. alignment shows that 

 the equinoxes were fixed as well as the solstices. 



(5) Of the twenty-nine circles I have examined, 

 fifteen are clock-star circles, two are May-year, and 

 three solstitial. Of special circles we have four facing 

 N. and one facing \\ . 



(6) .^rcturus and Capella were used as clock-stars in 

 Cornwall; in the higher la-titude of Aberdeen Castor 

 might have been used. 



(7) So far, and quite provisionally until a larger 

 number of circles is examined, I thinlc Castor was not 

 used. 



(8) In the clock-star circles the azimuths range from 

 N. 4° E. to N. 29° E. These azimuths, taking the 

 heights of horizon into account, give us N. declinations 

 from 34° 45' to 31°. If Capella is in question, the 

 dates lie between B.C. 1200 and B.C. 2000; if Arcturus, 

 B.C. 950 and B.C. 250. Mean dates are : — Capella, b.c. 

 1600; -Arcturus, B.C. 600. 



I append a diagram which shows the connections 



■The recumbent 



normal example. 



of the Coihie Muir Cii 



NO. 2004, VOL. 77] 



existing between the azimuths, the elevation of the 

 horizon — both measured quantities — and the declina- 

 tions, and dates of the use of the clock-stars. The 

 numbers on the curves refer to the fifteen clock-star 

 circles enumerated below : — 



I, Braehead Leslie; 2, Leylodge; 3, Loudon AA^ood; 

 4, Tomnagorn ; 5, Wanton Wells ; 6, Old Keig ; 7, 

 South Fornet; 13, Nether Boddam ; S, Aikey Brae; 

 9, Castle Eraser; 10, New Craig; 11, Loanhead of 

 Daviot ; 12, Kirkton of Bourtie ; 14, Cothie Muir; 15, 

 Eslie the Greater. 



Note that on the diagram the circle (Th is misplaced. 

 The azimuth should be 21° 15', not 11° 15'; conse- 

 quently the (13) circle should be moved along the 

 " 2° hill " curve until it touches the circle (5). 



As an illustration of the use of the curve, take the 

 case of the Cothie Muir circle, number 14. The true 

 azimuth across the circle, i.e. at right angles to the 

 recumbent stone, was found to be N. iS° 55' E., and 

 the elevation of the horizon in that direction 4*. Pro- 

 jecting the point where the 18° 55' azimuth ordinate 

 intersects the " 4° hill " curve, on to the declination 

 scale, we get 34° 42' N. as the declination. Referring 

 to the time scales for Arcturus and Capella, it is seen 



