Letter, from Henry Warburton to Sir John Herschel, dated at 45 Cadogan Place Autograph letter signed by sender. Approves of John Frederick William Herschel sharing Henry Warburton's findings. Henry Warburton on excellent terms with Augustus De Morgan. Suspects two integrals exist, one real and one imaginary, for P. S. Laplace's equation. 17 November 1854