Besides his written notes, interesting traces of his travels exist in the shape of the scattered leaves of a sketch-book filled with delicate drawings in silverpoint, chiefly views of places and studies of portrait and costume.
Leonardo's chief implements were pen, silverpoint, and red and black chalk (red chalk especially).
In silverpoint there are many beautiful drawings of his earlier time, and some of his later; but of the charming heads of women and young men in this material attributed to him in various collections, comparatively few are his own work, the majority being drawings in his spirit by his pupils Ambrogio Preda or Boltraffio.