The William Congreve died in 1729 he left a collection of books which his old friend and publisher, Jacob Tonson, described (in a letter preserved at the Bodleian) as genteel & well chosen. Tonson thought so well of the collection that he urged his nephew, then his agent in London, to purchase Congreve’s books. A small cross is marked before most of the 659 items--before all but fifty-eight (or thirty-seven, when allowance is made for duplicates). Perhaps these crosses were used in connection with an inventory taken in 1729 when the books were inherited by the young Duchess of Marlborough, or in 1740 when the books were incorporated by marriage settlement into the Leeds library.
