Note 90 — Chapter XIX · : The Monastery of St. Aliquis[89]: Buildings. Organization. An Ill-Ruled Abbey.
Reading edition
Clocks run wholly by weights were known as early as Charlemagne's time, and the famous "magician" Pope Sylvester II (see p. 303) studied their mechanism. By the thirteenth century they were slowly coming into general use. Of course, at first they had only one hand—showing merely the hours.