cloth industries. In the beginning of the 19th century the baize manufacture was altogether given up, although industry remained central to Leiden economy. This decline is painted vividly by the fall in population. The population of Leiden had sunk to 30,000 between 1796 and 1811, and in 1904 was 56,044. From the 17th to the early 19th century, Leiden was the publishing place of one of the most important contemporary journals, Nouvelles Extraordinaires de Divers Endroits, known also as Gazette de Leyde. 19th and 20th centuries On 12 January 1807, a catastrophe struck the city when a boat loaded with of gunpowder blew up in the middle of Leiden. 151 people were killed, over 2,000 were injured and some 220 homes were destroyed. King Louis Bonaparte personally visited the city to provide assistance to the victims. Although located in the centre of the city, the area destroyed remained empty for many years. In 1886 the space was turned into a public park, the Van der Werff park. In 1842, the railroad from Leiden to Haarlem was inaugurated and one year later the railway to The Hague (Den Haag) was completed, resulting in some social and economic improvement. Perhaps the most important piece of Dutch history contributed by Leiden was the Constitution of the Netherlands. Johan Rudolf Thorbecke (1798–1872) wrote the Dutch Constitution in April 1848 in his house at Garenmarkt 9 in Leiden. Leiden's reputation as the "city of books" continued through the 19th century with the establishment of publishing dynasties by Evert Jan Brill and Albertus Willem Sijthoff. Sijthoff, who rose to prominence in the trade of translated books, wrote a letter in 1899 to Queen Wilhelmina regarding his opposition to becoming a signatory to the Berne Convention for the Protection of Literary and Artistic Works. He felt that international copyright restrictions would stifle the Dutch publishing industry. Leiden began to expand beyond its 17th-century moats around 1896 and the number of citizens surpassed 50,000 in 1900. After 1920, new industries were established in the city, such as the canning and metal industries. During World War II, Leiden was hit hard by Allied bombardments. The areas surrounding the railway station and Marewijk were almost completely destroyed. The University of Leiden is famous for its many discoveries including Snell's law (by Willebrord Snellius) and the famous Leyden jar, a capacitor made from a glass jar, invented in Leiden by Pieter