The word seal refers to both the silver stamp and its wax impression. The city council attached this seal to important documents, signifying their approval of the contents, and as a token of authenticity to prevent fraud. The seal that was in use from 1654 to 1795 bore the coats of arms of the four burgomasters who were in office in 1654. The impression also depicts the ‘koggeschip’, symbol of the city’s trade.