French Drawings. The Essence of Line is a collection of over 900 drawings by French artists "from Ingres to Degas" by the Baltimore Museum of Art. I'd link to some highlights but the site did such a stellar job of it that I'll just direct you there. They also have some sketchbooks. Note that some of the drawings have short essays about them. As a related link, here is the famous Demonographia, with drawings of demons by Louis Breton and descriptions by Collin de Plancy.