Baltinglass - How They Told The Time
The Christian Irish had divided the year into months and weeks. But to make the Rule of St. Benedict work, the monks had to divide each day and night into hours. They gave each hour a name. For example prayers were to be said at the hours of Lauds, Prime, Terce, Sext, None, Vespers, and Compline both by day and night. So devices were needed to mark the passing of time.
Sundials were a common way to measure time. It is thought that the monks might have measured each day from sunrise to sunset and divided it into intervals. In the summer an “hour” would be longer than it was in winter. We know from the Rule that Vespers, the hour for eating during Lent, was always to be completed during daylight.
A marked candle had the advantage of being useful for day and night. The problem was that imperfections in the wax, and variations in the dimensions of the wick, could easily make the candle inaccurate.
An hour-glass was a more accurate way of measuring time. It was an expensive object, which had to be imported. All of these devices would be used to time the ringing of the bells, so that the monks and lay-brothers knew exactly what they had to do.