Letter, from John William Lubbock to Sir John Herschel, dated at Mansion House St. Autograph letter signed by sender. Many years ago John Frederick William Herschel questioned him about the calculation of the perturbations in an inclined orbit, the satellites of Herschel [Uranus] for example. Has only recently seen the light. Is now confident that he can calculate the perturbations of any planet in any orbit. Gives details and would be glad of John Frederick William Herschel's comments. undated