A date of 1498–99 is put on the work by Padre Sebastiano Resta who wrote to Giovanni Pietro Bellori saying that Leonardo had drawn the cartoon in Milan at the request of Louis XII of France. While this date has gained wide acceptance, the association with Louis XII has not. More recent historians have dated the work as early as the mid 1490s and, in the case of Carlo Pedretti and Kenneth Clark, as late as 1508–1510. Martin Kemp notes that the hydraulic engineering in the preparatory drawing in the British Museum dates the composition to around 1507–1508, when Leonardo was making similar studies in the Codex Atlanticus.