Missing Constable sketch discovered at British Library

"A 'lost' early sketch by John Constable and hundreds of original artworks and autographs by prominent 18th and 19th century artists have been discovered at the British Library. The beautifully bound 13-volume collection entitled The Life of J.M.W. Turner, R.A., features over 1,600 additions including portraits, views, autographs, engravings and original drawings including Turner correspondence and works by the artist's contemporaries, many previously unknown or considered 'lost'"