Letter, from Sir Charles Lyell to Sir John Herschel, dated at 53 Harley St. Autograph letter signed by sender. Origin of siliceous minerals sent by John Frederick William Herschel. Planning tenth edition of Principles of Geology. Convinced that changes in position of land and sea were principal causes of climate changes. Questions [James] Croll's theory of astronomical influences on climate, based on data from U. J. J. Le Verrier. Compares earth-pillars in Rhone valley with those in Tyrol. Wants tenth edition to include woodcut of John Frederick William Herschel's [1821?] drawings of earth-pillars. 31 January 1865