Magnascope

The Magnascope was an optical device created by Leonardo da Vinci using a pair of spectacles bought by Lorenzo de' Medici from Gilberto degli Specchi and aligning them on a paintbrush handle.

History
Leo used the Maganascope to observe Professor Pico in the Piazza and managed to spot a sketch of his Catapult amongst Pico's notes. (Da Vinci's Code