What machine did Leonardo da Vinci design for polishing curved mirrors?

Leonardo da Vinci designed a mirror-grinding machine for polishing curved mirrors.

The machine was intended to shape and smooth mirror surfaces with controlled mechanical motion. Leonardo studied both concave and convex forms, which require careful geometry because the curvature determines how light is reflected.

Mirror making was an important technical subject during the Renaissance. High-quality mirrors were difficult to produce, and a mechanical grinding system could make the work more consistent than hand polishing alone.

Leonardo’s design belongs to his broader investigations of optics, geometry, and workshop machinery. It was not a telescope itself, and it should not be confused with a lens-polishing machine, although both involve precision optical surfaces.