Returns JDH’s proofs. He is so involved in Origin he cannot judge force of JDH’s arguments. Some detailed comments.

Haldeman’s old paper [see 2470] clever, but does not have natural selection. Explaining adaptation has always seemed turning point of theory of natural selection.

A. D. Bache reports that self-recording instruments are installed at Washington observatory and ready to begin observations. ES is making field observations to confirm changes in magnetic lines in England since ES's 1837 survey. [JH annotation: Summary of Bache's letter. Joint survey by Smithsonian Institution and U.S. Coast Survey will begin when Bache receives full instructions from Sabine.]