Tenpo-tsuho (a coin that circulated in Japan during the end of Edo period and Meiji period) (天保通宝)
Tenpo-tsuho (a coin first minted in Tenpo era [1830 to 1843]) was a coin that circulated in Japan during the end of the Edo period and Meiji period. It was also known as Tenpo sen coins. The coin had an elliptical shape that resembled koban (former Japanese oval coin), having a square hole in the center, of which Chinese characters '天保通寳' (Tenpo-tsuho) was written on the front, '當百' (Tohyaku; referring that 1 Tenpo-tsuho was equivalent to 100 mon [a unit of currency]) and Kao (written seal mark) of the Goto family, kin-za (an organization in charge of casting and appraising of gold during the Edo period) on the back. It was made of copper and weighed 5.5 monme (about 20.6 grams).
It was minted in 1835. Its currency value was fixed to 100 mon, but in reality, it was passable as 80 mon. As it was not worth its face value (100 Kanei-tsuho [coins first minted in 1636 of Kanrei era]) at all in terms of weight, it brought about economic confusion and forging became common. Although it circulated even after the Meiji Restoration, it was officially forbidden to be used on December 31, 1891.
After the Meiji period, as the badge that Rikugun Daigakko (the Army War College) graduates wore resembled the Tenpo-tsuho, they came to be called 'Tenpo sen gumi' (team of Tenpo-tsuho).
On the other hand, as one Tenpo-tsuho coin was converted as eight rin (one Kanei-tsuho coin was one rin) in the new monetary system, it is said that people who were way behind the times or people who did not have ability to do so were sometimes cynically called 'Tenpo sen.'
Officially Minted Coins
Opposing the fact that the successful circulation of the Kanei-tsuho shinchu toshimonsen (bronze Kanrei-tsuho equivalent to four mon) made gin-za (an organization in charge of casting and appraising of silver during the Edo period) affluent, Sanemon GOTO, the Kin-za Okane aratame-yaku (an organizer of kin-za), proposed issuing more coins of higher rates. For this reason, the minting of the Tenpo-tsuho coin came to be led by the kin-za.
Its prescribed weight was 5 monme 5 bu (approximately 20.6 grams), its prescribed composition was 78 percents of copper, 12 percents of lead, 10 percents of tin; however, according to the analysis conducted by Japan Mint during the Meiji period, it was 0.037 percents of silver, 81.307 percents of copper, 9.742 percents of lead, 8.261 percents of tin, 0.056 percents of iron, 0.193 percents of zinc, 0.035 percents of antimony, 0.182 percents of arsenic, and 0.084 percents of sulfur.
The minting started on July 10, 1835 and was issued on October 23 of the same year; the number of coins minted up until January 1837 when it was temporarily stopped was 29,710,700. Minting was restarted in August 1837, and the number of coins minted until February 1842 was 10,024,500; the total coins during Tenpo era was 39,735,200. Some records say that the total of the coins minted between 1835 and 1842 was 39,732,200. It is thought this inconsistency was due to calculation errors caused by the misreading of '五' (five) and '二' (two).
After the minting was restarted on November 25, 1847, the number of minting was rapidly raised and it experienced its prime during the Manen era (1860 to 1861). It was also minted in the gin-za located in Naniwa of Osaka from December 1865 to January 1868, and after the Taisei Hokan (transfer of power back to the Emperor), Kaheishi (a government office taking over the kin-za and the gin-za) established by the new government minted 63,913,752 coins from May 15, 1868 to August 31, 1870; therefore the total number of coins minted from 1835 is said to be 484,804,054.
After Meiwa era (1764 to 1771), as the market price declined due to mass production of the Kanei-tsuho tetsu ichimonsen (iron Kanei-tsuho equivalent to one mon) and the shinchu shimonsen coins, the issuance of Tenpo-tsuho only caused the situation to worsen. Therefore, in order to prevent the downfall of the exchange rate of the sen (a unit of currency), the rate was officially fixed as 6,500 mon per ryo by the furegaki (bakufu orders) announced by the Edo bakufu in September 1842 to be stayed around 6,000 to 7,000 per ryo for a while, however, after the mass production in the end of the Edo period, it finally went over 10,000 mon per ryo in Keio era (1865 to 1868).
Furthermore, under the significant deviations from the face value since around Ansei era (1854 to 1859) in circulating the Kanei-tsuho do ichimonsen (copper Kanei-tsuho equivalent to one mon), the tetsu ichimonsen coins, and the shinchu shimonsen coins, and so on, the issuance of Bunkyu-eiho (a coin first minted in Bunkyu era [1854 to 1859]) brought the disorder of the exchange market; therefore in January 1863, the bakufu reordered to fix the rate of the Tenpo-tsuho by 100 mon, however, by reports that this rate was impossible and others, in June 1865, the Edo bakufu had to accept to circulate it by the fair market price not by the face value as follows with the standard of the tetsu ichimonsen coin equivalent to one mon and the Tenpo-tsuho equivalent to 100 mon:
Kanei-tsuho monsen and Mimijirozeni (one mon coin issued by the Tokugawa shogunate in 1714): 6 mon
Other Kanei-tsuho do ichimonsen coin: 4 mon
Kanei-tsuho shinchu shimonsen coin: 12 mon
Bunkyu-eiho shimonsen coin: 8 mon
Among the officially minted coins, the different styles are known such as one with 'Chokaku' (long framed surrounding the hole of a coin), 'Saikaku' (thin frame), 'Chukaku' (standard frame), 'Kokaku' (wide frame) and 'Chokaku' has a slightly longer '貝,' the part of the Chinese character '寳,' as well as the rectangle frame surrounding the hole. The other three types of coins have wider '貝' with similar styles of writing and the holes in the center are square shaped; therefore, they are categorized by the width of kaku (frame surrounding the hole of a coin), but some of them cannot be clearly categorized and are considered to have been made during the stage of transition from one type to another.
In the world of collecting coins, a opinion that claimed that coins minted between 1835 and the following year were called 'Chokaku' or 'Chukaku,' those between 1837 and 1842 were 'Saikaku,' and those after 1847 were 'Kokaku,' but the other argued that this categorization did not match the ratio of the number of existing coins and coins minted. In any case, it is agreed that 'Chokaku' coins were produced during the early period and 'Kokaku' were the late period.
Coins cast secretly in local areas
Since the Tenpo-tsuho only weighed five or six Kanei-tsuho coins and it was possible to produce a coin in 10 mon even less labor charge and reducing the weight by minting, the bakufu did not admit to issue the coin in local areas as 'Kinsei' (taboo), however some clans secretly minted the Tenpo-tsuho behind the imitative deception of the local coin issuance in the end of the Edo period. The Tenpo-tsuho coins immobilized and exchanged during the Meiji period totaled 586,740,000 which is 100 million more coins than those minted at the kin-za and the Kaheishi, and considering not all the Tenpo-tsuho coins were immobilized, the number of coins secretly minted is thought the be around 200 million.
The clans involved in the secret minting were more than following 10 clans which have been found: Mito, Kurume, Satsuma, Fukuoka, Oka, Tosa, Choshu, Aizu, Sendai, Kubota, and Morioka clans.
There are also many kinds of the Tenpo-tsuho coins whose origins were not clear called 'Fuchisen;' they are thought to have been produced by unknown clans or small private casting organizations.