The derivation is generally sup- posed to come from the German word Thaler (q.v.), and this in its turn takes its name from the silver coins struck about 1525 in the mining region of Joachimsthal in Bohemia.

It is the unit of value of the United States and is worth ten dimes or one hun- dred cents. The silver dollar was author- ized to be coined by an Act of Congress dated April 2, 1792, and the first coins were issued in 1794. They were originally of 416 grains; reduced in 1837 to 412.5 grains. The coinage of the silver dollar ceased in 1904.

The gold dollar was authorized by an Act of March 8, 1849, and abolished in 1890. It is of the weight of 25.8 grains, and was designed by James B. Longacre, the chief engraver of the mint.

Many of the British Colonies now use a silver dollar, called the British Dollar, and based on a metric system. This piece was authorized in 1895 and first struck for circulation in 1896, being intended prin cipally for Hong Kong and the Straits Settlements. It was originally 416 grains fine. The Bank of England dollar of the value of live shillings, and the Bank of Ireland dollar of the value of six shillings were both issued in 1804.