I've recently come across some wonderful old books on drawing and painting and thought I would share the online links to them for anybody who may be interested. This first link has several free excellent e-books on drawing. Including the following, which I would whole heartedly recommend:
'Pen Drawing: An Illustrated Treatise' by Charles Maginnis
'The Art of Illustration' by Henry Blackburn
'The Elements of Drawing' by John Ruskin
This second link opens up a copy of Alfred East's 'The Art of Landscape Painting in Oil Colour'.