Giant crossbow is Leonardo’s drawing in his Codex Atlanticus. The Codex Atlanticus is the largest collection of Leonardo’s drawings and it has been in Veneranda Biblioteca Ambrosiana of Milan since 1637. It consists of 119 pages made in over 40 years (1478-1519) and it characterized by various themes: from astronomy to art and philosophical meditations, recipes, studies of hydraulic engineering, optics and mathematics and war machines like the one in question.
At the center of the drawing there is a large crossbow on wheels, illustrated with raised and shortened point of view that allows to identify a large number of details. The crossbow was probably designed to have a long-range shot and to impress the enemies, but even with multiple studies regarding the theme (see Codex f. 147A), the master never tried to build a prototype and it was only made in recent times. On the left side there are two enlargements of the shooting device accompanied with notes and indications. (“This the method for how the instrument looks that goes with the cord. And its release comes from the blow of that maul over the nut.” “This makes the same effect as the instrument above, except that its release is triggered with the lever, and its noiseless“) On the left side da Vinci wrote notes with precise indications reading the size and operation of the instrument: “This crossbow opens at its arms, that is were the rope is attached, 42 braccia, and is at its thickest, without its armature, 1 and 2 thirds braccia, and its thinnest, 2/3 of a braccio. It has an elevation (or draw) of 14 braccia. Its carriage is 2 braccia wide and 40 long it carries 100 pounds of stone; and when it is moving, the carriage lowers itself and the crossbow directs itself along the length of the carriage.”
Drawings like this and many others related to military art seem to paraphrase the famous “presentation letter” that da Vinci wrote to Ludovico il Moro around 1483 to persuade him to hire him in the Milanese court. In fact, among other various services Leonardo offered himself as an intelligent inventor of war machines (the letter is preserved in the Codex Atlanticus; f. 1082 recto).
Pedretti C., Leonardo da Vinci. Fragments at Windsor Castle from the Codex Atlanticus, London 1957;
Pedretti C., The Codex Atlanticus of Leonardo da Vinci. A Catalogue of its Newly Restored Sheets, Part One, Vol. I-VI, New York 1978;
Marinoni A., Il Codice Atlantico, in Leonardo all’Ambrosiana.Il Codice Atlantico. I disegni di Leonardo e della sua cerchia, a cura di A. Marinoni e L. Cogliati Arano, Milano 1982, cat. 14;
AA.VV., Leonardo da Vinci. Il Codice Atlantico della Biblioteca Ambrosiana di Milano, trascrizione critica di Marinoni A., presentazione di Pedretti C., Tomo I, Firenze 2000, p. 201;