For the English North American colonists, however, the Spanish peso or "piece of eight" has always held first place, and this coin was also called the "dollar" as early as 1581. After the Declaration of American Independence, the United States dollar was introduced in 1792 at par with this coin at 371.25 grains = 0.7735 troy ounces = 24.0566 g. Alexander Hamilton arrived at these numbers based on a treasury assay of the average fine silver content of a selection of worn Spanish dollars.Oxford English Dictionary, entry on "dollar", definition 2 ("The English name for the peso or piece of eight (i.e. eight ), formerly current in Spain and the Spanish American colonies").
