No edition stated, but presumably the second printing, as number sequence to copyright page reads 3 5 7 9 10 8 6 4 2. A fine copy in DJ. With THUMB-PRINT of Stephen Hawking to title page. The page is INSCRIBED "To Bob.to bodly go.with best wishes from Stephen Hawking. Director of Research, Centre for Theoretical Cosmology, University of Cambridge, U.K." (The inscription presumably in the hand of Judith Croasdell, who has acted as witness - a stamp mid-page reads "Right thumb-print of S. W. Hawking withnessed by Judith Croasdell.").