Translation of a letter, from Christian Huygens to Robert Moray Original letter no longer exists but was dated 31 October 1664 Discussing the rise and fall of mercury, and Slusius of Liege's thermometer; doubts Campani's tool for grinding lenses, and asks about the production of large lenses; expects a parcel of glass from his father, that the Parisians are impressed with his father's microscope, and that his father was impressed with Campani's telescope 1664