O'Reilly — On the Orientation of Some Cromlechs. 595 



give rise to a tendency to expansion and a subsequent scaling off of 

 flat flakes, leaving behind a rough, slightly undulated surface, such as 

 is presented by this northern stone. 



From this point of view 1 am inclined to think that it may have 

 been a glaciated plate of granite, smooth at least on one side, and used 

 on that account. In close proximity to these smooth patches on this 

 south-western stone occurs an incision about 10 cm. long, by 

 1^ cm. broad, and ^ cm. deep, which may have been done by hand, 

 but which might really be likewise the result of contact with a hard 

 angle of a rock under glacial or erosive action, but it is difficult to deter- 

 mine to which cause it may have been due. 



The cap is a very remarkable mass of granite in size, and presents 

 an inclination to the horizon of about 14°. The under surface is singu- 

 larly even and very slightly arched. The cap is shown in horizontal 

 projection on the plan, and also in the western and northern eleva- 

 tions in the Plates. "What is of very great interest is the channel 

 cut across the upper face in the fonn of a bow, as shown on the plan, 

 and bearing two sets of incisions — one on the north side, the other on 

 the south. These part from the channel, and extend about 6 to 10 cm. 

 up the slope of the face or towards the western end of the stone. Both 

 the channel and the incisions have suffered from atmospheric action, 

 and have therefore lost somewhat of their original sharpness of outline ; 

 nevertheless, they are still perfectly distinct, and the intervals between 

 the incisions have been measured as carefully as the state of the 

 sui-faces allows. They are as follows : — 



mm. mm. mm. mm. mm. 



South side, . 142, 154-5, 278-5, 233-5 — 

 Is'orth side, . 221-5, 162-5, 91-5, 159-5, 127-5 



The measures marked on the plan are cm., and are only 

 approximative. There are twelve incisions in all. One on the south 

 side is, however, so elementary or effaced as to be doubtful. The 

 intervals are given not merely as belonging to the plan, but also 

 because they may represent some unit of measurement. I do not 

 attempt to speculate on their use further than to suggest that, if there 

 be admitted evidence of the utilization of the monument for solar 

 observations, these incisions may really have had the same object, 

 and might have been in connexion with a gnomon of which the place 

 would have been at some point to the east ; possibly among the stones 

 shown on that side of the chamber in the plan. 



