 While studying the Merwede, he began to form plans to help keep the lower areas of the Netherlands dry.It was at this time that Kruik changed his name to the Latin "Cruquius" after his first publications of maps and measurements.In 1725 he wrote a famous letter to Willem 's Gravesande, a Dutch professor of physics and astronomy at Leiden, proposing an empirical deductive research method to solve the water problems of the Netherlands.