17th century German Hour-glass at the National Maritime Museum, London - From the curators' comments: "A four-fold glass with 15-, 30-, 45- and 60-minute glasses. The glasses bear the numbers 1, 2, 3 and 4 in red paint on each bulb, indicating the number of quarter-hours measured. There is also a flower painted on each bulb in red paint. They are filled with a white substance that is possibly ground eggshell. The central joints are bound with twine."