Christiaan Huygens (1692–1695) and Ole Rømer (1644–1710) closely interacted during the 1670s, when they were both in and around the Académie Royale des Sciences in Paris. They were part of a small group with a shared interest in precision instruments. In the course of their interactions Rømer played a decisive role in two of Huygens renowned achievements: the wave theory of light and the design of a planetarium. Rømer's discovery of the finite speed of light, confirmed Huygens main supposition that light propagates at finite speed. The news of the discovery renewed his interest in the nature of light, resulting in 1677 in the formulation of the principle of wave propagation. Rømer's subsequent criticism of Huygens' theory induced him to seek experimental verification of his claims which he successfully did in 1679. Huygens' planetarium of 1682, in the meantime, was a direct response to the instrument Rømer presented at the Académie in 1680. According to Huygens, his instrument provided a more economic and more truthful mechanical representation of celestial motions. Despite their affinity in matters of ingenuity, Huygens and Rømer never became really close. After their departure from Paris, contact between them virtually ceased. This may be explained by the socio-cultural differences between both savants.