On February 1st 1966, the world was struck by a sensational piece of news: two manuscripts by Leonardo were discovered in Madrid at the Biblioteca Nacional. In the 1830s, an error in cataloguing concealed 700 holograph pages by Leonardo. Their discovery makes an enormous contribution in revealing new aspects of his intellect.
In the first volume, the studies revolve around the principles of mechanics and their numerous practical applications in devices of high perfection and great beauty, accompanied by many notes on hydraulics.
The second volume deals mainly with urbanistic topics, including studies for fortifications at Piombino in Tuscany and the canalisation of the Arno River, as well as important transcriptions from a part of the treatise on military engineering by Francesco di Giorgio Martini, a gift of the author to Leonardo. It includes studies on waves, the flight of birds, musical instruments and geographical maps with plans for canals, as well as very valuable information on the books owned by Leonardo.
The codex finishes with a section on the project for the casting of the equestrian monument to Francesco Sforza.