Maestro Leonardo of Florence.
[Footnote: So Leonardo writes his name on a sheet with sundry short notes, evidently to try a pen. Compare the signature with those in Nos. 1341, 1348 and 1374 (see also No. 1346, l. 33). The form “Lionardo” does not occur in the autographs. The Portrait of the Master in the Royal Library at Turin, which is reproduced—slightly diminished—on Pl. I, has in the original two lines of writing underneath; one in red chalk of two or three words is partly effaced: lionardo it... lm (or lai?); the second written in pencil is as follows: fatto da lui stesso assai vecchio. In both of these the writing is very like the Master’s, but is certainly only an imitation.]
Taken from The Notebooks of Leonardo da Vinci edited by Jean Paul Richter, 1880.