All manuscripts acquired by donation or purchase are added to this open-ended series, either singly or in groups, if they are: a) in a format compatible with the collection, i.e. manuscript books or rolls, or unbound material that can be filed; and b) not integral to an archive or individual collection. There is, however, much archival material, most notably correspondence, held in the General Manuscript Collection. Individual manuscripts of particular interest include: A volume of medieval astronomy texts is the oldest scientific manuscript in the National Library (NLW MS 735C). The first section of the volume was written around 1000 and the second dates from c.1150. Both sections were copied in the Limousin region of France. The Latin text describes the constellations with the aid of diagrams and colour illustrations of Zodiac images. The Black Book of Basingwerk (NLW MS 7006D) is a 15th-century manuscript containing a version of Brut y Brenhinedd, a Welsh translation of Geoffrey of Monmouth's Historia Regum Britanniae. Particular features of interest include the medieval wooden board binding and the decorated initials embellished with gold. The Llywarch Reynolds Manuscripts (NLW MS 970 to 997) are the 28 volumes that Llywarch Owain Reynolds bequeathed to the Library in 1916. The most notable among them is the 17th century collection of Welsh poetry, Llyuyr Hir Llywarch Reynolds. The Book of Llandaff (NLW MS 17110E), also known as Liber Landavensis, is an ecclesiastical manuscript written between 1120 and 1140. The Llanbeblig Book of Hours (NLW MS 17520A) is a small manuscript book compiled around 1390. The manuscript has a number of entries in the calendar that connect it to Wales, including a celebration of the dedication of the church of Saint Peblig, Caernarfon. Isabella Godynogh (d. 1413) was possibly its original owner. The full-page miniatures, illuminated with gold, and the fine lettering indicate the value of the book. The Llanbeblig Hours is the only known illuminated manuscript that contains the iconographical Lily Crucifixion motif, and may be the earliest example of its use in any media. NLW MS 20143A is a manuscript of the laws of Hywel Dda written in Welsh around 1350. It is unusual in that it retains a medieval binding. The Tintern Abbey Bible (NLW MS 22631C) is a 13th-century Bible that has a known association with the medieval library of the Cistercian monastery at Tintern, Monmouthshire. It was purchased by the National Library for £30,000