This transfer established the formation of the British Library. National libraries The first true national library was founded in 1753 as part of the British Museum. This new institution was the first of a new kind of museum – national, belonging to neither church nor king, freely open to the public and aiming to collect everything. The museum's foundations lay in the will of the physician and naturalist Sir Hans Sloane, who gathered an enviable collection of curiosities over his lifetime which he bequeathed to the nation for £20,000. Sloane's collection included some 40,000 printed books and 7,000 manuscripts, as well as prints and drawings. The British Museum Act 1753 also incorporated the Cotton library and the Harleian library. These were joined in 1757 by the Royal Library, assembled by various British monarchs. The first exhibition galleries and reading room for scholars opened on 15 January 1759, and in 1757, King George II granted it the right to a copy of every book published in the country, thereby ensuring that the Museum's library would expand indefinitely. Anthony Panizzi became the Principal Librarian at the British Museum in 1856, where he oversaw its modernization. During his tenure, the library's holdings increased from 235,000 to 540,000 volumes, making it the largest library in the world at the time. Its famous circular Reading Room was opened in 1857. Panizzi undertook the creation of a new catalogue, based on the "Ninety-One Cataloguing Rules" (1841) which he devised with his assistants. These rules served as the basis for all subsequent catalogue rules of the 19th and 20th centuries, and are at the origins of the ISBD and of digital cataloguing elements such as Dublin Core. In France, the first national library was the Bibliothèque Mazarine, which evolved from its origin as a royal library founded at the Louvre Palace by Charles V in 1368. At the death of Charles VI, this first collection was unilaterally bought by the English regent of France, the Duke of Bedford, who transferred it to England in 1424. It was apparently dispersed at his death in 1435. The invention of printing resulted in the starting of another collection in the Louvre inherited by Louis XI in 1461. Francis I transferred the collection in 1534 to Fontainebleau and merged it with his private library. The appointment of Jacques Auguste de Thou as librarian in the 17th century, initiated a period of