Recto: Studies for casting apparatus, and miscellaneous notes, c.1492-93 (pen & ink and chalk on...

On the recto of the sheet, drawings of ground plans and elevations of a bronze-casting apparatus, including designs of pulleys and cog-wheel mechanisms, with accompanying notes. On the verso, notes and diagrams of ground-plans of casting apparatus, and literary quotations as if from a commonplace book. These are some of Leonardo's designs for the casting of a bronze equestrian monument to Francesco Sforza , Duke of Milan (1401-66). Such a monument is first mentioned in a letter of November 1473 from his son Galeazzo Maria to the commissar of the ducal works, instructing him to find an artist capable of carrying out the work. Apparently nothing was done at this time; Galeazzo Maria was murdered in 1476, and his brother Ludovico went into exile between 1477 and 1479. On his return to Milan, Ludovico revived the project, and we have our first notice of Leonardo's interest in the monument in an undated draft of a letter to Ludovico, through which he hoped to gain employment at the Sforza court: 'I can carry out sculpture in marble, bronze or clay, and also I can do in painting whatever may be done, as well as any other, be he who he may. Again, the bronze horse may be taken in hand, which is to be to the immortal glory and eternal honour of the prince your father of happy memory, and of the illustrious house of Sforza.'