Ptolemy's Optics: measuring angles of refraction
Óptica de Ptolomeo: medición de ángulos de refracción
- Date
- c. 150 · confidence medium
- Place
- Alexandria, Egypt
- Credited to
- Claudius Ptolemy
- Field
- Communication
What was discovered
Ptolemy uses a graduated disc to measure refraction angles between air, water and glass and compiles tables, alongside studies of mirrors and binocular vision. It is the first known experimental study of refraction.
The Greek original is lost and the work is known from a 12th-century Latin translation (Eugene of Palermo) made from Arabic, which raises questions about the transmitted text; the measured values follow a quadratic rule, not the sine law.
What it led to
- atmospheric refraction tables in astronomy
- Alhazen's experimental optics
- correction of astronomical positions for refraction