Huygens Christiaan (1629–95), Dutch physicist and astronomer who ranked among the leading experimental scientists of his time and influenced many other thinkers, including Leibniz. He wrote on physics and astronomy in Latin (Horologium Oscillatorium, 1673; De Vi Centrifuga, 1703) and in French for the Journal des Scavans. He became a founding member of the French Academy of Sciences. Huygens ground lenses, built telescopes, discovered the rings of Saturn, and invented the pendulum clock. His most popular composition, Cosmotheoros (1699), inspired by Fontenelle, praises a divine architect and conjectures the possible existence of rational beings on other planets. J.-L.S.