216 Proceedings of the Royal Irish Academy. 



pendant la nuit afin d^etre avertis des heares de V office, et pour les rilles, 

 ou les crieuTs faisaient coimaitre la marclie du temps, usage qui se 

 conserve dans plusieurs provinces." 



" On a a tort fait descendre jusqu'au 13™* siecle et meme jusqu'au 

 j^me siecle, 1' invention des horloges sonnantes ; elles se trouvent 

 deja citees dans les statuts de I'ordre de Citeaux, reunis vers I'annee 

 1120. On voit en effet dans ces statuts un article par lequel on 

 defend toutes sonneries de cloclies, meme a 1'h.orloge, depuis la messe 

 de jeudi saiat, Jusqu'a celle du samedi saint; un autre article aussi, 

 qui enjoint au sacristan de regler I'horloge de sorte qu'elle sonne et 

 qu'elle I'eveille pendant I'hiver, avant matines ou avant les noc- 

 tui'nes," &c. 



This article distinctly points out the observation of the stars 

 during the night for the fixation of the hours of office ia the monas- 

 teries of the early Christian period, and such observation implies an 

 observatory or part of the building capable of being so applied, such 

 as a to-wer or elevated part dominating the surrounding parts of the 

 building, any trees in the proximity, and having a free and extended 

 view towards the horizon. Let it be remarked, e7i passant, that such 

 conditions are presented by the highest story of the round towers. 

 Another and more important requirement for the early Christian 

 chui'ches called for such regular observations and for corresponding- 

 observatories. It was that of the correct determination of the Easter 

 time. It is a matter of history the difierence that subsisted for nearly 

 two centuries between the Churches of Ireland and England, and that 

 of Eome and the East, as regards the proper period for the cele- 

 bration of Easter. Dr. Healy, in his Insula Sajictorum et Doctorum 

 (1890), p. 233, says: " Of course the system of computing the date of 

 Easter in use in Ireland and in England, at the beginning of the 

 seventh century, was that which was introduced by St. Patrick him- 

 self, and which he acquired in the schools of France and Italy. From 

 [p. 234] the very beginning, however, much diversity of practice 

 existed between the Churches of the East and "West, and even between 

 some Churches in the West itself, in reference to the date of Easter 

 Day." He then gives an account of the results of the Synod of Aries 

 in this regard, of the Ificene Synod of a.d. 325, and of the reference 

 to the Church of Alexandria for the exact date thereof, and its notifi- 

 cation to the Boman Church, by which it was finally made known to 

 the other Churches. He says: "The Alexandrian usage ultimately 

 prevailed, but was finally accepted in the Western world only about 



