Has been requested by Gideon Mantell to write JH a letter of introduction for a Lieut. H. I. Thomas, a friend of Davies Gilbert. Thomas wishes to be the bearer of any letter or parcel CL may have. Believes that a copy of the President's speech he sent may be lost in the post. Thinks that JH's theory of subterranean isothermal lines interesting. Dined with the Somervilles last Sunday.

No summary available.

Charles Babbage will publish JH's volcanic theory in Ninth Bridgewater Treatise, together with JH's letter to R. I. Murchison. William Whewell read both at Geological Society. Babbage wants to compare JH's theory with passage from Bishop [Samuel] Butler. Whewell's notion of new species. Charles Darwin's new theory of coral islands is forcing CL to give up CL's volcanic crater theory. [Letter continues 28 May.] Sends copy of Babbage's Treatise with quotes from JH. News of Charles Wheatstone's submarine telegraph and David Brewster's proof that diamond is of vegetable origin.

Ideas expressed by JH in his previous letter to CL (see JH's 1836-2-20) about secular variations of isothermal surfaces of the interior of the earth were similar to ideas expressed by Charles Babbage in a paper to the Geological Society. This was drawn to JH's attention by CL and by R. I. Murchison. JH argues that he did not know of Charles Babbage's paper, and goes on to point out how JH's ideas differ. Concludes with mention of having re-discovered the sixth satellite of Saturn, not seen since its discovery by JH's father, William.