O'Reilly — On the Orie)itatio}i of Some CromlecJis. 603 



It would seem therefore that, independentlr of the direction of 

 the principal parts of these monuments, a means of orientation was 

 attained by the builders or users of them by fixing single stones, 

 •either due east and west or north and south, and placing tliese in 

 relation to other parts of the monument, so that a corresponding north 

 and south or east and west line of direction was determined. As in 

 some way agreeing with this view is the fact that the east and west 

 line determined as mentioned and indicated in the plan is that of the 

 entrance to the present enclosure of the monument, which was 

 formerly surrounded, according to tradition, by a ring of stones with 

 an entrance way, which in all probability, if not certainly, is that 

 still existing. 



SHAIfKILL CeOMLECH. 



(PL XIX., figs. 1 & 2.) 



The Shankill cromlech is situated in a field to the south of 

 €arriggollaghan, near where the old road from the quarries attains 

 its highest level. It differs from all the others about Dublin in being 

 built of smaller stones, which have evidently been taken from the 

 neighbouring quartzite beds of CarriggoUaghan. Five stones remain 

 in situ, four of them forming the walls of the chamber, and the fifth 

 forming the covering stones, as shown in the accompanying plan and 

 elevation (Plate XIX.). In this case the orientation is practically due 

 •east and west, and the position of the monument such that the chamber 

 would receive the rays of the rising sun at equinox, and would allow of 

 the observation of its period. It may have been intended also to allow 

 of the observation of the solstices ; but, as the monument is evidently 

 incomplete, it is unnecessary to examine it from this point of view, 

 although the fact that the diagonals of the chamber in its present 

 state make, with the east-west direction of the sides, angles which 

 approximate to 23° 28' (as would be required for that purpose) is 

 very suggestive. The situation of the cromlech is very commanding, 

 and the view embraces a large extent of horizon. 



Lakch Hill CKOiiLECH. 



(PI. XX., figs. 1 & 2.) 



The Larch Hill cromlech is situated in a field lying to the west 

 of and below the level of the old road, which, parting from White- 

 church bridge, leads up to Kilmashogue mountain and along its side. 



