What is Tenpō Ichibugin
Tenpō Ichibugin (天保一分銀) is a counted silver coin from the Edo period, first issued in Tenpō 8 (1837). The denomination is one bu, and according to the official market price table in the permanent display catalog, 1 ryō of gold coin = 4 bu = 16 shu, with 4 Ichibugin silver coins equaling 1 ryō (catalog). The permanent display catalog at the Currency Museum notes the silver content of Tenpō Ichibugin as 99% (rounded value). The shape is rectangular, with the three characters "一分銀" on the obverse and "定 銀座 常是" on the reverse, surrounded by a cherry blossom motif on both sides (image from the Currency Museum Collection catalog). The transition from weighed silver coins (chōgin and mameitagin) to counted silver coins is summarized in Introduction to Edo Silver Coins (Chōgin and Mameitagin).
Background of issuance (Currency Museum 'History of Japanese Currency')
According to the 'History of Japanese Currency' by the Currency Museum, the Edo shogunate issued quantitative silver coins "Meiwa Gomamegin" in 1765, to be exchanged for gold coins at the official rate (1 ryō of gold = 60 momme of silver). In 1772, they issued the counted silver "Meiwa Nanryō Nijūgin." With proactive measures to promote circulation, such as providing loans to shogunate money changers, counted silver coins became widely circulated nationally in the first half of the 19th century (History of Japanese Currency). The same 'History of Japanese Currency' notes that the Edo shogunate implemented the Bunsei (1818-) and Tenpō coinage reforms (1832-) to supplement its financially strained state but led to price inflation. The issuance of Tenpō Ichibugin (1837) took place after this Tenpō coinage reform (1832-) (catalog, History of Japanese Currency). The permanent display catalog cites Tenpō Ichibugin as a counted silver coin that was in extensive circulation at the time of the opening of ports.
Records of weight and fineness
The fineness of Tenpō Ichibugin is listed in the permanent display catalog at the Currency Museum (page on the opening of ports and gold coin outflow) as 99% (rounded value). The precise values (in thousandths) for weight and fineness claimed to be recorded in the Mint Museum guide are pending publication until the original can be directly verified. As for mintage volume, existing count, and dimensions, definitive primary records have not been confirmed from reference materials. The figures in this category are organized with sources in Complete Record of Tenpō Ichibugin.
Design and inscriptions (image from collection catalog)
An image of Tenpō Ichibugin from the Currency Museum's Collection catalog 'Illustrated Catalog of Japanese Coins' (ⅡA Edo b 24/101) shows the three characters "一分銀" lined vertically on the rectangular obverse, and "定" "銀座" "常是" on the reverse. A cherry blossom rim runs around both sides. Differences in character styles, meanings, and origins of the reverse characters, and classification of variants exceed the range confirmed by reference materials and are not discussed here. When examining an individual, one checks these inscriptions against the catalog and Mint Museum's weight and fineness, and verifies the provenance.
Relation to Ansei Ichibugin (within the scope of materials)
The permanent display catalog (page on the opening of ports and gold coin outflow) states that the shogunate issued Ansei Nijūgin (June 1859, fineness 85%) just before the opening of ports and, following protests from Western countries, stopped its issuance. They then issued Ansei Ichibugin (August 1859, fineness 87%) using melted Western silver for exchange purposes. The same page shows Tenpō Ichibugin as 1837, with a higher fineness of 99% compared to Ansei Ichibugin's 87%. The individual clues to distinguish between the two go beyond the scope confirmed by reference materials and are not discussed here. Also refer to the sections on Ansei Ichibugin and Ichibugin.
Materials and records
Reference materials for Tenpō Ichibugin include the permanent display catalog at the Currency Museum (pages on official market price, opening of ports and gold coin outflow), the Currency Museum's 'History of Japanese Currency,' the Currency Museum Collection catalog 'Illustrated Catalog of Japanese Coins' (Four Tenpō Ichibugin: ⅡA Edo b 24/101, 24/102, 24/201, 24/290), and the Mint Museum guide. Individual price and auction examples are only listed in the market records if corroborated records (event, lot, source URL, date verified) have been obtained. Check record availability at View Auction History.