values depicted a dragon, the middle values a carp, and the dollar values a wild goose. The paper used for these stamps had a watermark in the form of a yin-yang symbol. In 1898, these were superseded by similar designs produced by engraving in London, and inscribed CHINESE IMPERIAL POST on a Chinese supplied watermarked paper of varying thickness. The watermark can be difficult to detect on the thicker paper. New printings of the stamp, beginning in 1899 were on unwatermarked paper, but there are no recorded usages of this variety until 1901. These stamps continued in use until the end of the empire. During that time some colours were changed to comply with Universal Postal Union regulations, and three new values were added. The first commemorative stamps of China were issued in 1909 to mark the 1st year of the reign of the Xuantong Emperor. The set of three (2c, 3c, 7c), all depicted the Temple of Heaven in Beijing. Republic of China Beiyang Government The revolution of 1911 resulted in overprints on the imperial stamps in 1912; at Foochow to indicate that the post office was effectively a neutral area available to both sides, and at Nanking and Shanghai reading "Republic of China" (from top to bottom: ). An additional set of overprints was produced by Waterlow and Sons in London, and postmasters throughout the country made their own unofficial overprints using the same characters. The first new designs of the Republic were two commemorative sets of 12 each, the first set depicting Sun Yat-sen and second Yuan Shikai, both issued on 14 December 1912. The definitives of the "Junk issue" went on sale 5 May 1913, and continued in use into the 1930s. The low values featured a junk, while values from 15c to 50c showed a farmer reaping rice, while the dollar values depicted the three-part gateway to the Hall of Classics in Beijing. The series was first printed in London, then in Beijing from 1915; they can be distinguished by close examination. The designs were re-engraved in 1923, and a number of design features were changed; for instance, the whitecaps in the water underneath the junk were removed, and the water darkened. China produced five new commemorative issues, of four stamps each, during the 1920s. The first, issued on 1921-10-10 to commemorate the 25th anniversary of the Chinese Post Office featured then president Xu Shichang