Brewster stereoscope
An optical device that uses two converging lenses and a septum to present a separate image to each eye, creating a three-dimensional effect when viewing stereoscopic photographs. Invented by Sir David Brewster in 1849, it improved upon Charles Wheatstone’s earlier mirror-based stereoscope. Brewster’s lenticular design was more compact and portable, contributing to its commercial success in the mid-19th century.