*Sundials: telling the time in medieval Ireland* Before the general introduction of mechanized clocks, the requirements of daily life and the necessity of differentiating the times for the daily rituals of the Church led to the production of stone sundials at important places where the skills and knowledge to create such monuments had developed. Approximately 30 medieval stone sundials have been recorded in Ireland, with about a dozen dating to the early medieval period. The earliest Irish examples usually comprise a large rectangular slab or pillar-stone, often with an expanded semicircular head or carved with a semicircular arc. The semicircular portion is the dial and in the centre is a hole that usually penetrates all the way through the stone. The hole was designed to hold the gnomon – a wooden or metal projecting pin – which would cast a shadow on the face of the sundial. The face of each dial is calibrated using a varied number of incised radial lines (“rays”) that extend from the hole. The number of radial lines carved on the dial differs from one monument to the next. But the most common division of the dial is into four segments defined by five lines, with the four segments of the dial denoting four “tides” or roughly three-hour time periods, though the length would vary according to the time of year. The five lines from left to right represent the canonical hours of Prime (6am), Terce (9am), Sext (noon), Nones (3pm) and Vespers (6pm); a presumed complementary division of nighttime into four parts represents the octaval division of the day. This was the prevalent system before the 11th or 12th century for marking the times when prayers would be recited. Such dials thus operate on the basis of a 12-hour daytime block from 6am to 6pm, with the central vertical line always corresponding to noon. In an age before clocks, these primitive devices were essential as a way to determine the correct time for prescribed services and rituals and clearly highlight the importance of the regularized monastic and clerical routines. Not surprisingly then, the vast majority of medieval sundials have been found at church sites. Of course, the sun did not always shine in medieval Ireland, so sundials could not be depended upon entirely. Read more about the Irish collection of medieval sundials here: https://irishheritagenews.ie/sundials-telling-time-in-medieval-ireland/