To learn more about time in the Middle Ages, here are some suggestions.
Readings on Calendar Images - Bridgit Ann Henisch, The Medieval Calendar Year (Pennsylvania State University Press, 1999) - Colum Hourihane (ed.), Time in the Medieval World (Princeton University Press, 2007) - James Webster, The Labors of the Months in Antique and Medieval Art (Princeton University Press, 1938)
Readings on Clocks - Jean Gimpel, The Medieval Machine (Penguin Books, 1976), Chapter 7, " The Mechanical Clock: The Key Machine" - Anna Götlind, Technology and Religion in Medieval Sweden (Falun, 1993), Chapter 5, "Mechanical Clocks in Medieval Sweden"