Museo Galileo
Virtual Museum
Nonius (vernier)
Nonius (vernier)

Cursor index for precise measurement of the fractions of a linear or circular graduated scale. Initially called a "nonius," after the Portuguese Pedro Nuñez (1502-1578), who described an instrument of this type in 1542. However, it was Pierre Vernier (1584-1638) who redesigned the device in the form commonly used today. For this reason, it is also called a "vernier."