During the Ottoman period, the dilapidated state of the patriarchs' tombs was restored to a semblance of sumptuous dignity. Ali Bey who, under Muslim disguise, was one of the few Westerners to gain access, reported in 1807 that,all the sepulchres of the patriarchs are covered with rich carpets of green silk, magnificently embroidered with gold; those of the wives are red, embroidered in like manner. The sultans of Constantinople furnish these carpets, which are renewed from time to time. Ali Bey counted nine, one over the other, upon the sepulchre of Abraham. Hebron also became known throughout the Arab world for its glass production, abetted by Bedouin trade networks which brought up minerals from the Dead Sea, and the industry is mentioned in the books of 19th century Western travellers to Palestine. For example, Ulrich Jasper Seetzen noted during his travels in Palestine in 1808–09 that 150 persons were employed in the glass industry in Hebron, based on 26 kilns. In 1833, a report on the town appearing in a weekly paper printed by the London-based Religious Tract Society wrote that Hebron's population had 400 Arab families, had numerous well-provisioned shops and that there was a manufactory of glass lamps, which were exported to Egypt. Early 19th-century travellers also noticed Hebron's flourishing agriculture. Apart from glassware, it was a major exporter of "dibse", grape sugar, from the famous Dabookeh grapestock characteristic of Hebron.