and the dissolution of the monastery. Along with the manuscripts are numerous seal impressions which are themselves of historic importance. A collection of more than 30,000 seal impressions dating from the twelfth century onwards is preserved in the National Library of Wales, with examples including the seals of Welsh princes, ecclesiastic and papal seals, and in a variety of designs. Pictures The charter of the National Library of Wales states that pictures should be collected which portray places in Wales or people of Welsh background. Images in a number of different media are collected including paintings, drawings, prints and digital formats. The collection contains over 4000 framed paintings and drawings including paintings of Dolbadarn Castle and Aberdulais Mill by J. M. W. Turner and examples of the work of the landscape artist Richard Wilson, who influenced Turner, and Wilson's pupil, Thomas Jones of Pencerrig. A set of original drawings of Welsh scenes that Thomas Rowlandson made during his 1797 tour of Wales with Henry Wigstead, and a set of original drawings of castles, abbeys and cities by Samuel and Nathaniel Buck were donated by Sir John Williams. The Library also has some two hundred original watercolour drawings of Welsh landscapes by John Warwick Smith, and collections of original drawings of Welsh interest by Philip J. de Loutherbourg and S. H. Grimm. The collection of engraved prints illustrate a wide variety of Welsh topography and aspects of Welsh culture, and also show the development of the art of engraving. Every method of engraving is represented in the collection, which also contains examples of the work of famous engravers. There are around 15,000 Welsh portraits in various media and a further 50,000 photographs and negatives in the Library's collection. Portraits include the National Library's main benefactors, Sir John Williams, Sir John Herbert Lewis, Lord Rendel, and Lord Davies of Llandinam; prominent Welsh individuals including David Lloyd George and Hwfa Môn; and, those by artists with a connection to Wales, such as Hugh Hughes, William Roos and Christopher Williams. Self-portraits by modern Welsh artists are also collected and include Keith Andrew, David Jones, Charles Tunnicliffe and Kyffin Williams. There are also many photographic portraits of Welsh individuals in the 1880s and 1890s that were taken by John Thomas. There is a large collection of the iconic work of Kyffin Williams in the Library, which includes his paintings of north Wales, sketches and watercolours