<P> With the adoption of the decimal U.S. currency in 1794, there was no longer a U.S. coin worth ​ ⁄ of a dollar but "two bits" remained in the language with the meaning of one quarter dollar, "four bits" half dollar, etc . Because there was no one - bit coin, a dime (10 ¢) was sometimes called a short bit and 15 ¢ a long bit . (The picayune, which was originally ​ ⁄ real or ​ ⁄ bit (​ 6 ⁄ ¢), was similarly transferred to the US 5 ¢ - piece .) </P> <P> In addition, Spanish coinage, like other foreign coins, continued to be widely used and allowed as legal tender by Chapter XXII of the Act of April 10, 1806 until the Coinage Act of 1857 discontinued the practice . </P> <P> Robert Louis Stevenson describes his experience with bits in Across the Plains, (1892) p. 144: </P> <Dl> <Dd> In the Pacific States they have made a bolder push for complexity, and settle their affairs by a coin that no longer exists--the BIT, or old Mexican real . The supposed value of the bit is twelve and a half cents, eight to the dollar . When it comes to two bits, the quarter - dollar stands for the required amount . But how about an odd bit? The nearest coin to it is a dime, which is, short by a fifth . That, then, is called a SHORT bit . If you have one, you lay it triumphantly down, and save two and a half cents . But if you have not, and lay down a quarter, the bar - keeper or shopman calmly tenders you a dime by way of change; and thus you have paid what is called a LONG BIT, and lost two and a half cents, or even, by comparison with a short bit, five cents . </Dd> </Dl>

Where did the phrase two bits come from