The Coinage Act of 1792 attempted to set the ratio of gold to silver.
The California Gold Rush flooded the market with gold changing the premium of gold to silver, creating a run on silver. So, in 1853, Congress reduced the size of small silver coins. The quarter shrunk from 6.68 grams to 6.22 grams. The dollar remained the same.
After 1853, the two-bit coin (the quarter) no longer had two bits of silver. In 1857 Congress forbade the use of foreign coinage in trades, effectively ending the use of pieces-of-eight as an international monetary supply.
The mint later raised the weight of the quarter back to 6.25 grams. 20th century coinage has the oddity that 4 quarters weigh 25 grams, while the dollar weighs 26.73 grams. 4/4 < 1.
I am working on a project which calculates the price of two bits. I've been in a quandary about whether I should use the weight of a quarter of dollar or the weight of the quarter (the two-bit coin) for my calculations.
I finally decided to use the weight of the quarter as written in the 1792 coinage act. It is closer to the weight the US Founders would have experienced in colonial days. The Coinage Act says a quarter will "contain ninety-two grains and thirteen sixteenth parts of a grain of pure [...] silver." There are 480 grains in a troy ounce. A bit weighs 92.8125/480 troy ounces. At market close on 6/25/2011 a troy ounce of silver sold for 34.73. So, two-bits is $6.72.
I wonder if I could get a shave and a haircut for two-bits?