Hourglass. Grains of sand fall from the upper to the lower glass bulb,measuring a fixed length of time. Hour glasses were first used by the Romans in about 1 BC | |
Licence : | Droits gérés |
Crédit: | Science Photo Library / Terry, Sheila |
Taille de l’image : | 3801 px × 4615 px |
Model Release : | Non requis |
Property Release : | Non requis |
Restrictions : | - |