Tide dial

[11] Monks were called to these hours by their abbot[12] or by the ringing of the church bell, with the time between services organised in reading the Bible or other religious texts, in manual labour, or in sleep.

The need for these monastic communities and others to organize their times of prayer prompted the establishment of tide dials built into the walls of churches.

They began to be used in England in the late 7th century and spread from there across continental Europe through copies of Bede's works and by the Saxon and Hiberno-Scottish missions.

There are more than 3,000 surviving tide dials in England[14][b] and at least 1,500 in France,[16] mainly in Normandy, Touraine, Charente, and at monasteries along the pilgrimage routes to Santiago de Compostela in northwestern Spain.

With Christendom confined to the Northern Hemisphere, the tide dials were often carved vertically onto the south side of the church chancel at eye level near the priest's door.

Cole suggests they were used as markers to quickly and easily reconstruct the tide dials following a fresh whitewash of the church walls with chalk or lime.

[18][19] Nendrum Monastery in Northern Ireland, supposedly founded in the 5th century by St Machaoi, now has a reconstructed tide dial.