two books in one volume, c.1716, with front piece showing cherubs with a box microscope, 26 -160- 12 pages, 20 folded plates to rear, in original cream velum with brass clasps Note: Original first edition, rare, of this important work by the instrument maker Johann Gottlieb Hertel (1683-1743), the book covers the grinding and polishing of lenses and the construction of optical instruments. It contains the description of various forms of microscopes, including notes of their construction including micrometres, a plane mirror and mechanical stage; all this is shown on an impressive and large plate engraved by Winckler. Although there are, according to COPAC, various copies of this book in institutes and libraries. According to Herald Moe ‘Story of the Microscope’ only one or two copies have the plate showing Hertal’s Microscope - according to Hartel. Johann Georg Leutmann (1667-1736) was a professor of mechanics and optics at the St. Petersburg Academy.