I have to admit I’m not quite sure what this is. I came across it from a link somewhere (and have unfortunately forgotten the connection), and bookmarked it under “cool drawing resource”.
Carracci was a 16th Century Italian master renowned for his beautiful frescos and paintings, and credited with inventing caricature in the modern sense. It is his drawings I have always noticed, though; they stand out even among other great masters of the time.
The pieces on this site are from a book that looks like it may be a drawing manual based on Carracci’s drawings, featuring both light outline drawings and finished renderings, presumably by a later French artist, of faces, facial features, hands, feet and other items related to drawing people.
Though not as beautiful as Carracci’s delicate and subtle drawings in red chalk, these engravings are particularly interesting for the contrast between the lightly rendered and fully rendered versions, and the instructive array of eyes, ears, mouths and other features. It should be as useful to artists today as it was 400 years ago.