NATURE 



[March 25, igrg 



that Borlase"s N. point was less than 3° to the 

 west. 



Working on this basis, I joined up the centres of 

 the circles, as shown on the plans (Figs. 2 and 3), 

 .-uid carefully measured the resulting azimuths. These 

 1 sent to Mr. Thomas, asking him if the slight modi- 

 fications of azimuths that I had introduced had 

 sensibly altered his values for the corresponding 

 ;mgular elevations. After a second series of observa- 

 tions, he replied that the elevations were the same 

 for the modified azimuths as they were before. 



It at once became obvious that the alignments 

 divided themselves into two groups — one erected for 

 the observations of the May-year, the other for solsti- 

 tial phenomena — and with each group there is asso- 

 ciated a clock-star which affords a means of deter- 

 mining the approximate date of each group. For 

 this reason I give two separate plans (Figs. 2 and 3) 

 showing the separate groups of alignments, and two 

 separate tables giving the respective results. I will 

 deal with the May-year circles first, table I. (Fig. 2). 



These results agree with the May-year results pre- 

 viously obtained from the study of other Cornish 

 circles, and to illustrate this I bring together a selec- 

 tion of the results previously published (table IJ.). 



An examination of Fig. 2 shows that the azimuths 

 given in the table are exactly those obtained by 

 joining up the centres of the circles and adopting the 

 N. — S. line derived from Mr. Thomas's two measures 

 of direction. The results justify the 3° change of the 

 orientation of Borlase's plan. 



The Solstilial Year. 

 Joining up the centres of H, G, D, and C, as shown 

 1 Fig. 3, we obtain the results given in table III., 



results which are obviously connected inter se and 

 with the solstitial year. 



lU.—Solstitial Alignments at Botallek (lat. 50° 8' JV.). 



th (Mr. Thomas's) Declinat 



Centre of circle H to centre of circle C 

 Centre of circle D to centre of circle C 

 Cent, of circ. H to cent, of small circ. G 



N. 53 o E. 

 S. 49 30 E. 

 N. 16 o E. 



I 45 

 1 35 



23 41 N. 

 23 44 S. 

 37 28 N. 



Solstitial sun (summer) 

 Solstitial sun (winter) 

 Arcturus (clock-star) 



NO. 2056, VOL. 80] 



