hadden ze 1000 jaar geleden ook al zandlopers?

Zet de link er dan maar helemaal bij: http://en.wikipedia.org/wiki/Hourglass "The origin of the hourglass is unclear, although it may have been introduced to Europe by an 8th-century monk named Luitprand, who served at the cathedral in Chartres, France. It was not until the 14th century that the hourglass was seen commonly, the earliest firm evidence being a depiction in the 1338 fresco Allegory of Good Government by Ambrogio Lorenzetti."