Neither the Presidential dollar coin, introduced 11 years ago, nor the Eagle dollar coin, introduced 3 years ago, remained in circulation long: people simply preferred spending paper dollars.

11年前发行的Presidential dollar和3年前发行的Eagle dollar中的任何一种都没有在流通领域存在很长时间：人们只是更愿意使用纸币。

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Any silver coin makes a sufficient substitute for a sixpence coin that is difficult to find due to its being in circulation till 1971.

任何的银硬币可作为由于在循环中而很难被找到的六便士的充分替代直到1971年。

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That change was owing to the influence of iron coin casting and circulation and to cater to the need of military actions.

发生这种变化的原因是铁钱铸造、流通的影响和军事行动的需要。

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Controlling the rate at which coins were created, he said, meant there would never be a surge or shortfall in the number of bitcoins in circulation, either one of which could rapidly change the value of each coin.

BBC: Rewards set to halve for digital money miners

Some 25 million pieces were in circulation in 1863 and '64, according to research by Robert Leonard Jr. of the Chicago Coin Club.

FORBES: Substitute Money