Astronomical Instruments. Circle. Plate II.

This print depicts two significant developments in astronomical instrumentation: Tobias Mayer’s original reflecting circle of 1752 and Jean-Charles Borda’s improved version from 1777. These devices were used for measuring angular distances between celestial bodies with greater precision, marking an evolution in observational astronomy. Drawn by J. Farey and engraved by A. Anderson, the image was published in 1820 in Rees’s Cyclopaedia, a major early 19th-century encyclopedia of science and technology.