Copy letter, from Sir John Herschel to George Biddell Airy, dated at Slough Copy letter in John Herschel's hand. Thanks George Biddell Airy for the second volume of his observations; wishes the publications of the Astronomer Royal were as good; adds some comments on polarization of light by liquids, and then talks about observing Georgium Sidum [Uranus], and deals with the orbits of satellites of planets generally. 27 July 1830