This telescope has an achromatic objective, a four-element erecting eye
piece, and a wooden tube with two sections that screw together in the middle.
It was made after the invention of achromatic lenses in 1758, and before 1774 when Edward Nairne (1726-1806) went into partnership with Thomas Blunt. Ref: Deborah Warner, "Edward Nairne: Scientist and Instrument Maker," Rittenhouse 12 (1998): 65-93.