Sextant

Location, location

Until satellite navigation became widespread, this type of instrument was a vital tool for sailors and aviators. It is called a sextant because the metal arc is one-sixth of a circle. Looking through the coloured glass filters, an observer could measure the altitude of bright objects such as the Sun or Moon without risking eye damage. Captain Cook used a sextant similar to this one to navigate around the Pacific islands in the 1770s.