the ocean currents and winds required of a sailing chart, rather than a formal map. The analysis also suggests that Arabic-speaking pilots with a detailed knowledge of the African coast were involved in the cartography. There is little attempt to provide an accurate 2-D representation; instead, the sailing instructions are given using a 24-point compass system with a Chinese symbol for each point, together with a sailing time or distance, which takes account of the local currents and winds. Sometimes depth soundings are also provided. It also shows bays, estuaries, capes and islands, ports and mountains along the coast, important landmarks such as pagodas and temples, and shoal rocks. Of 300 named places outside China, more than 80% can be confidently located. There are also fifty observations of stellar altitude. Size of ships According to 's novel Sanbao Taijian Xia Xiyang Ji Tongsu Yanyi (Eunuch Sanbao Western Records Popular Romance, published 1597), the first expedition had: "Treasure ships" (, Bǎo Chuán) nine-masted, 44.4 by 18 zhang, about long and wide. Equine ships (, Mǎ Chuán), carrying horses and tribute goods and repair material for the fleet, eight-masted, 37 by 15 zhang, about long and wide. Supply ships (, Liáng Chuán), containing staple for the crew, seven-masted, 28 by 12 zhang, about long and wide. Transport ships (, Zuò Chuán), six-masted, 24 by 9.4 zhang, about long and wide. Warships (, Zhàn Chuán), five-masted, 18 by 6.8 zhang, about long. On the ships were navigators, explorers, sailors, doctors, workers, and soldiers, along with the translator and diarist Gong Zhen. Six more expeditions took place from 1407 to 1433, with fleets thought to be of comparable size. Marco Polo and Ibn Battuta both described multi-masted ships carrying 500 to 1,000 passengers in their translated accounts. Niccolò de' Conti, a contemporary of Zheng He, was also an eyewitness of ships in Southeast Asia, claiming to have seen five-masted junks weighing about 2,000 vegetes, that is Venetian butt. Christopher Wake estimated a burthen of 1300 tons. The ship of Conti may have been a Burmese or Indonesian jong. The largest ships in the fleet, the Chinese treasure ships described in Chinese chronicles, would have been nearly twice as long as any other wooden ship recorded thereafter until the 20th century, surpassing Admiral Nelson's HMS Victory, long, which was launched in 1765, and the Vasa of 1627. The first ships to attain long were 19th