抄録
(1) Seven years of rich harvests of lowland-rice crops per Tan, 1887, 1890, 1898, 1904, 1914, 1920, 1933 and seven years of lean harvests, 1884, 1897, 1902, 1905, 1931, 1934, 1935, were taken out mathematically from sixty years 1880∼1930. (2) In the lunar calendar, one month more is added to twelve months, in seven years during nineteen years, to adjust it to the solar calendar. It is called an intercalary month, in the lunar calendar. The year of the solar calendar, which may comprise such an intercalary month as mentioned, is named the year of an intercalary month, by the author. They are as follows : 1881, 1884, 1887, 1890, 1892, 1895, 1898, 1900, 1903, 1906, 1909, 1912, 1914, 1917, 1919, 1922, 1925, 1928, 1930, 1933, 1936, 1938. (3) Comparing (1) with (2), following relations are seen. Rich harvests in lowland-rice crops per Tan occur more frequently in years of an intercalary month. Years of no intercalary month, have more chances of lean harvests.
