Willem Jacob 's Gravesande (26.09.1688-28.02.1742) was a Dutch scientist. He was born in 's-Hertogenbosch. He studied at the University of Leiden (1704—07), and from 1717 he was professor of mathematics and astronomy and from 1734 professor of philosophy at that university.
His work in physics was in optics, mechanics, heat, hydrostatics and hydraulics. He invented the first heliostat (1719) and made a number of discoveries in physics; in particular he demonstrated the thermal expansion of solids (the experiment with 's Gravesande's ring). He popularised Newton's ideas.