From about 1805 until 1876 (which roughly parallels the last half of the best of ukiyo-e, and the period from which prints are most commonly found today), many (and in some periods almost all) woodblock prints contained a date seal, using the oriental cyclical calendar system. Reading these date seals allows the dating of prints, usually to within a month.
The Japanese used (along with several other calendrical systems) the Chinese zodiacal calendar, which is a twelve-year cycle, with each year having an associated animal, e.g. rat, ox, etc. (Anyone who has ever eaten in a Chinese restarant will no doubt recall this from the placemats.) The date seals usually included both a cyclical year indication, in the form of the (often stylized) character for the year's animal, along with the numeral for the month.
Although this only technically narrows it down to a group of years, spaced
twelve years apart, other indications (e.g. the artist's working period, or
the form of his signature, or the form of the censor seals, which
usually allow one to ascertain the exact date.
The following characters (given in archaic and standard form) are used to
denote an intercalary month:
Years which contain an intercalary month (as noted above) are given in brackets; the number given is the number of the month preceding the intercalary month.
|Zodiac Year||Years For That Animal|
|Rat||1804||1816 (8)||1828||1840||1852 (2)||1864||1876|
|Ox||1805 (8)||1817||1829||1841 (1)||1853||1865 (5)||1877|
|Tiger||1806||1818||1830 (3)||1842||1854 (7)||1866||1878|
|Hare||1807||1819 (4)||1831||1843 (9)||1855||1867|
|Dragon||1808||1820||1832 (11)||1844||1856||1868 (4)|
|Horse||1810||1822 (1)||1834||1846 (5)||1858||1870 (10)|
|Goat||1811 (2)||1823||1835 (7)||1847||1859||1871|
|Monkey||1812||1824 (8)||1836||1848||1860 (3)||1872|
|Cock||1813 (11)||1825||1837||1849 (4)||1861||1873 (6)|
|Dog||1814||1826||1838 (4)||1850||1862 (8)||1874|
As mentioned above, to find out which particular year is meant (out of the group named by a particular animal), one has to use other indications, in particular the form of the censor seals to ascertain the exact date.
James Self, Nobuko Hirose, "Japanese Art Signatures: A Handbook and Practical Guide", Tuttle, Rutland, 1987This invaluable reference work is now unfortunately out of print, and completely unavailable on the used book market, which is why the information is being made available online here.