Letter, from P. O'Callaghan to Sir John Herschel, dated at Cookridge Hall, Leeds Autograph letter signed by sender. Heard from Louisa [John Frederick William Herschel's daughter] that John Frederick William Herschel was interested to hear about the [Leeds] Literary and Philosophical Society. Gives details and recent lectures. Would be pleased for John Frederick William Herschel to give a lecture. 30 July 1858