There are considerable differences between the Allen manuscript and the printed text, indicating that there must have been another manuscript or manuscripts between it and the (missing) proofs, which also could have been heavily corrected. (See manuscripts of Modern Painters I). 'Vol. 2' in Allen 10r must have been another notebook containing a draft of the passage in the printed text from 'It is not, however, always easy' to 'the varnishing of it' (3.89-90); compare Allen 12r. There was probably also a manuscript notebook or notebooks, now lost, containing drafts of the second half of the work (see order of composition of Modern Painters I.)