Question: Sundials are considered the world’s oldest scientific instrument. What do they measure?
Answer: Time. The base, or dial, of a sundial has markings, and as the sun moves, the shadow from the sundial’s pin falls on different sections, indicating how much time has passed. First used in Ancient Egypt, sundials of varying shapes and sizes were employed by almost every culture until they started to be replaced by mechanical clocks in the eighteenth century.