DOLLAR, a silver coin at one time current in many European countries, and adopted under varying forms of the name else where. The word "dollar" is a modified form of thaler, which, with the variant forms (daler, dalar, daalder, tallero, etc.), is said to be a shortened form of Joachimsthaler. This Joachimsthaler was the name given to a coin intended to be the silver equivalent of the gold gulden, a coin current in Germany from the 14th cen tury. In 1516 a rich silver mine was discovered in Joachimsthal (Joachim's dale) , a mining district of Bohemia, and the count of Schlick, by whom it was appropriated, caused a great number of silver coins to be struck (the first having the date 1518) , bearing an effigy of St. Joachim, hence the name. The Joachimsthaler was also sometimes known as the Schlickenthaler. The first use of the word dollar in English was as applied to this silver coin, the thaler, which was current in Germany at various values from the 16th century onwards, as well as, more particularly, to the unit of the Germany monetary union from 1857 to 1873, when the mark was substituted for the thaler. The Spanish piece-of-eight (real) was also commonly referred to as a dollar; it was used both in the Spanish-American and in the English colonies.
On July 6, 1787, the dollar was adopted by the Continental Congress as the monetary unit of the United States. Actual coin age was not begun until after the enactment of the law, April 2, 1792, providing for a dollar of 371 a grains of pure silver or 416 grains of standard silver. An act of March 3, 1849, directed the coinage of gold dollars of 25-A grains, of which 23.22 grains were to be fine gold, and by act of Feb. 12, 1873 this became the American unit of currency. According to the Constitution, Con gress has the power to regulate the currency, and under that power Congress by act of May 12, provided that the weight of gold in the dollar might be fixed by the President but not below 6o% of its then weight. By proclamation of the Presi dent, Jan. 31, 1934, the gold in the dollar was fixed at 15 grains, nine-tenths fine, a reduction of approximately 41 per cent. The silver dollar contains 412-1 grains, nine-tenths fine. No gold is now coined, having been withdrawn from circulation in The present subsidiary coins are the half-dollar or 50-cent piece, the quarter-dollar or 25-cent piece, the dime or 1 o-cent piece, all in silver; the 5-cent piece in nickel; and the 1-cent piece in copper.
The Spanish piece-of-eight was the ancestor of the Mexican, the Newfoundland, and the Spanish-American dollar.