Huygens' marine clock designed to show standard time at sea for the purpose of determining longitude, 1659. Christiaan Huygens (April 14, 1629 - July 8, 1695) was a prominent Dutch mathematician, astronomer, physicist, probabilist, horologist and scientist. Huygens is remembered especially for his wave theory of light. He investigated the use of lenses in projectors and is credited as the inventor of the magic lantern. His work included early telescopic studies of the rings of Saturn and the discovery of its moon Titan. His invention of the pendulum clock was a breakthrough in timekeeping. He also developed a balance spring watch in the same period as Robert Hooke.