O'Reilly — Old Chnrchca of Dalke;/ Town and Inland. 217 



A.D. 530, when explained and developed by Dionysius Exiguus, 

 This, the correct system, therefore lays down three principles : — (first) 

 Easter Day must be always a Sunday ; never on, but next after the 

 14th day of the moon; (secondly) that the 14th day, or the full 

 moon, should be that on, or next after, the vernal equinox ; and (thirdly) 

 the equinox itself was invariably assigned to the 21st of March. 

 "Whilst, however, the continental Churches aimed at uniformity after 

 a troublesome experience of their own errors, the Irish and British 

 Churches, practically isolated from their neighbours, tenaciously clung 

 to the system introduced by St. Patrick." 



This citation is made in order to show the importance attached to 

 the question in the early Churches, the differences that existed between 

 them, the effect of their isolation from the continental communities, 

 and the intimate dependence of the exact date on that of the vernal 

 equinox. It is true that from a very early date a cycle of years was 

 adopted, and brought into use for the purpose ; but it is clear that the 

 actual observation and determination of the vernal equinox were not 

 the less necessary as a check on,, and a control of the computation ; 

 and hence in the Western churches, and more particularly in those of 

 Ireland, such means of observation must have been provided for, and 

 have been employed from the time of St. Patrick. 



In support of this point of view, it may be interesting and useful 

 to cite the inscription which appears on the pavement floor of the 

 north transept of the Church of St. Sulpice in Paris, in connexion 

 with the meridian line traced on that floor. It is thus referred to in 

 T3aedeker's " Guide to Paris," 1891, p. 252 :— " St. Sulpice, Transept. 

 — On the pavement here a meridian line was drawn in 1743 with the 

 signs of the Zodiac. It is prolonged to an obelisk of white marble, 

 which indicates the direction of the north ; while towards the soiith it 

 corresponds with a closed window, from a small aperture of which a 

 ray of the sun falls at noon on the vertical line of the obelisk." This 

 description, rather curt and wanting in detail, does not sufficiently 

 describe these details, nor show the significance of this remarkable 

 piece of scientific work. Not only is the meridian plane clearly and 

 sharply defined by a ribbon of brass, inlaid on edge into the floor, but 

 it is marked with signs of the Zodiac on the floor, and on the gnomon 

 or obelisk situated in the north transept, and serving to indicate by 

 horizontal lines traced thereon the positions which the ray of sun- 

 light, coming from the south transept window, occupies at the various 

 periods of the year corresponding to the inscribed signs thereon. 



