Spanish: Weigh-master. In the Spanish colonial mints the weigh-master oversaw the weighing of ingots, planchets and struck coins. He also was required to check the weight of the coins at least every six months, and was responsible for the money shipped from the mint. The royal laws usually required this officer to be present whenever coins or metals were moved or counted. Another official with a similar task, called the weight inspector (fiel or contraste) was employed in the larger mints. Also maestro de la balanza.
Source: Numiscadero Spanish to English Glossary (Gary Beals)