E. Cobham Brewer 1810–1897. Dictionary of Phrase and Fable. 1898.
Proof.
A printed sheet to be examined and approved before it is finally printed. The first proof is that which contains all the workman’s errors; when these are corrected the impression next taken is called a clean proof and is submitted to the author; the final impression, which is corrected by the reader ad unguem, is termed the press proof.
