The fourth known Bohemian to come to America was Mathias Bush,7 a native of Prague who arrived in New York City in the 1740's and later moved to Philadelphia or Germantown. He was naturalized in 1749, one of the first to benefit from the Act of Parliament of 1740 authorizing the naturalization of foreigners after a seven-year residence in the colonies. He married into the prominent Simon Gratz family and became a leader in the synagogue established in Philadelphia in the 1760's. He was a merchant and ship owner, and during the French and Indian War an army purveyor.

There are numerous records showing that Bush was a prominent member of the Jewish community in Philadelphia. He is known to have owned property in Philadelphia and Northampton Counties, Pennsylvania, and in Fredrick and Hampshire Counties, Virginia. On October 25, 1765, he affixed his signature to the Philadelphia Merchants Non-Importation Act,8 the first American document of civic rights on record. During 1782 and 1783 he served as collector of taxes for Germantown.