Portrait of the Flemish physicist Simon Stevin, 1548-1620. Stevin entered the Dutch government service and developed a system for flooding parts of Holland to defend them from invasion. He is noted for his demonstration that hydrostatic pressure in a liquid depends only on the depth of the liquid and not on the shape of the container. In mathematics he is credited with introducing the decimal system for representing fractions. He also worked on statics. He was an advocate of writing scientific works in the vernacular rather than in Latin, as was the custom of the day. He married at the age of 64 and had four children.