Another specimen, the Wuwei Bronze Cannon, was discovered in 1980 and may possibly be the oldest as well as largest cannon of the 13th century: a 100 centimeter 108 kilogram bronze cannon discovered in a cellar in Wuwei, Gansu Province containing no inscription, but has been dated by historians to the late Western Xia period between 1214 and 1227. The gun contained an iron ball about nine centimeters in diameter, which is smaller than the muzzle diameter at twelve centimeters, and 0.1 kilograms of gunpowder in it when discovered, meaning that the projectile might have been another co-viative. Ben Sinvany and Dang Shoushan believe that the ball used to be much larger prior to its highly corroded state at the time of discovery. While large in size, the weapon is noticeably more primitive than later Yuan dynasty guns, and is unevenly cast. A similar weapon was discovered not far from the discovery site in 1997, but much smaller in size at only 1.5 kg. Chen Bingying disputes this however, and argues there were no guns before 1259, while Dang Shoushan believes the Western Xia guns point to the appearance of guns by 1220, and Stephen Haw goes even further by stating that guns were developed as early as 1200. Sinologist Joseph Needham and renaissance siege expert Thomas Arnold provide a more conservative estimate of around 1280 for the appearance of the "true" cannon. Whether or not any of these are correct, it seems likely that the gun was born sometime during the 13th century.