Letter, from Henry Oldenburg to [Christiaan] Huygens, dated at London Concerning his observations of the solar eclipse; concerning the publication of the position of fixed stars from a Greek manuscript copy of the 'Almagest'; states that he will send Wallis's paper on tides; that his telescope is nearly ready; concerning errors in 'Specimen recognitionis' published by Erasmus Bartholin at Copenhagen; concerning an instrument for measuring small distances which can be attached to a telescope; concerning distribution of his 'Cometographia' and 'Selenographia' 23 January 1669