Incomplete letter, from Sir Charles Lyell to Sir John Herschel, dated at 16 Hart St. Autograph letter signed by sender. Preparing fifth edition of Principles of Geology, using John Frederick William Herschel's facts about boiling seeds. Mathematical error in CL's climate theory. CL's first speech as president of Geological Society. Criticizes Royal Society [of London] John Frederick William Herschel's volcanic theory was too complex; will incorporate it into later editions. Benefits to science of Charles Babbage's social parties. Latest publications in geology. P.S. Glad to learn that John Frederick William Herschel thinks origin of new species may occur through intermediate causes; Germans criticized this. CL chooses not to engage in controversies. Speculates on successive extinction of species. Notes on African hot springs. 1 June 1836