O'Reilly — Old Churches of Dalkey Town and Island. 215 



monasteries of the sixth and seventh centuries, such as that of 

 Ai'magh and lona, followed the eastern model." 



So far there is merely a presumption that these towers served for 

 look-out and ohservation purposes ; but being constructed for the 

 safety of the community, this could only be secured by such continual 

 observation and outlook. Moreover, another important requii'ement 

 of the religious communities rendered such observations necessary, 

 more particularly that of the heavenly bodies — that was the division 

 of the hours of the day and of the night, for the regular occupations 

 and offices of the community. The division of the day into hours 

 must have been in some way arrived at, and, moreover, announced 

 regularly to the members of the community. How the hours of the 

 day or night were marked in the pagan and early Christian times of 

 Ireland is not distinctly stated, so far as I can find. That the round 

 towers or '* cloictheachs" served in some way for that purpose the 

 very name implies ; and yet Petrie barely concedes that they may 

 have been thus used. In the East, and in those latitudes wherein 

 the sun is generally visible during the day-time, the use of the 

 gnomon was common until the introduction of the " clepsydra," and 

 later on of the clock ; but in a climate such as that of Ireland, the 

 sky of which is so frequently overcovered by clouds, and continuous 

 sunshine thus exceptional, means must have been found at an early 

 period of mechanically dividing the time of the day and of the night ; 

 and also a means of making known these divisions to the public, or 

 to those requiring this knowledge for their daily avocations. 



In the " Dictionnaire Encyclopedique de la France" (Ph. le Bas, 

 Paris, 1843), under the heading "Horloges," p. 485, the author 

 describes the wonderful clock or clepsydra made for the Calif of 

 Bagdad, Haroun-al-Raschid, in a.d. 807, and presented by him to 

 Charlemagne; and then continues: " On a done ignore absolument 

 jusqu'au 12""= siecle, la division du temps par le moyen des roues 

 dentees, et des pignons qui s'y engrenaient. Ce n'est que depuis ce 

 temps, qu'on a commence 4 fabriquer, pour les cloches des eglises, des 

 grandes horloges, qui fonctionnaient au moyen d'un poids attache a 

 la plus grande roue et faisant aller tout le mecanisme. Des ouvriers 

 intelligents perfectionnerent ensuite cet appareil, en y ajustant un 

 rouage correspondant a un marteau, qui frappait sur un timbre sonore 

 les heures indiquees par le cadran. Ce perfectionnement devint d'une 

 grande utilite, et pour les monasteres, o-k avant son mtroduction il 

 faillait que les religieux proposassent des gens ])our observer les ctoiks 



