Sand timer. This device is used to measure a set period of time by the flow of sand (blue) from one chamber to the other through a narrow gap | |
Lizenzart: | Lizenzpflichtig |
Credit: | Science Photo Library / Lawry, Lawrence |
Bildgröße: | 3741 px × 4674 px |
Modell-Rechte: | nicht erforderlich |
Eigentums-Rechte: | nicht erforderlich |
Restrictions: | - |