Letter, from George Biddell Airy to Sir John Herschel, dated at Edensor, Bakewell Autograph letter signed by sender. Copy of letter to Hugh Percy (3rd Duke of Northumberland) stating that the Duke's offer of a refracting telescope of great power, to Cambridge Observatory would be a valuable gift. To John Frederick William Herschel: Remarks on gift of telescope, planet reduction money, and on his geological exploration of the Charnwood Forest. 20 August 1833