Letter, from Christian Huygens to Henry Oldenburg, dated at the Hague Discussing Wallis's new treatise; concerning the discovery of a new star in Cygnus; concerns observations of Saturn with his 22-foot telescope, and looks forward to obaining the observations of Hooke and of Hevelius; introduces the work of de Monceaux, who has made observations whilst in the Levant, and states that he will be arriving at the Royal Society Read to the Royal Society on 27 October 1670 October 1670