222 Proceedings of the Royal Irish Academy. 



of tlie objects for which, the building was intended, receives a certain 

 support from the relation of position of the chiu'ch to the rock-face, 

 on which is cut the Greek cross, mentioned and figured by "Wakeman 

 in his Paper already cited. This rock is situated at 11-15 m. (about 1 4 

 yards) west of the western door ; not, however, due west thereof, but 

 north of west, a certain number of degrees (PI. XYII., fig. 1). It had 

 long occurred to me that the Irish crosses showing a circle with cross- 

 arms might have some connexion with solar observations, serving, for 

 instance, as a means of determining the position of the sun at certain 

 periods, or rather fixing certain periods by the shadow of the pillar 

 and cross at certain positions and elevations of the sun. I was there- 

 fore led to examine attentively the position of this cross relatively to 

 the east and west direction of the building. On the ground that the 

 determination of the direction of the setting sun is equally important 

 as that of the rising sun, if accui'ately determined, for the fixation of 

 the solstices or equinoxes, it might be assumed a priori, that some 

 means would be found to ensui-e this determination ; and on examining 

 the position of the Grreek cross in question relatively to the plan of 

 the building, it was found that a line passing through the north-west 

 edge of the building, due east and west, passes nearly through the 

 centre of the cross ; and probably if very exact measurements of the 

 orientation and of the position of the cross relative to the sides of the 

 building were made, this relation would be brought out more markedly^ 

 It would seem as if, when the building was completed, and observa- 

 tions fi'om the belfry height could be made on to the horizon, leading 

 to the recognition of the correct east and west direction, the cross 

 was cut as a fiducial point which, with the north-west edge of the 

 building, gave the true east and west direction. 



The lineal measurements given in this Paper are in centimetres '^ 

 and, perhaps, it may not be out of place to here offer an explanation 

 of the use of this unit of measurement in this case, rather than of 

 English feet and inches, usually employed in this country for such 

 pui-poses. The explanation is simply that the author had been 

 continually in the habit of employing the metre in connexion with 

 geological and stratigraphical studies and measurements, and therefore 

 continued to use it when measuring buildings. In consequence of 

 this use of the metre, a veiy interesting observation has resulted, and 

 a very important question arises. 



Having been, when in IN'orthern Spain, continually under the neces- 

 sity of converting the "vara" or Castilian yard (the unit of measure- 

 ment of the country) into metre units and vice versa, the relation of the 



