Letter, from Hensleigh Wedgwood to Sir John Herschel, dated at 16 Gower St. Autograph letter signed by sender. Gives reason for writing [Principles of Geometric Demonstration (1844)]. Plans later edition in which Hensleigh Wedgwood will cite John Frederick William Herschel's statement in [Quarterly Review]. Role of sense experience in axioms. 1844 or later