Edinburgh - Thanks WW for his paper ['On the Fundamental Antithesis of Philosophy', Transactions of the Cambridge Philosophical Society, 7, pt. 2, 1845?]: 'The question at issue [between WW and John Herschel] appears to me to be not about the [fact] of the [indifferent] action of the mind, but about its extent. Everyone admits, I presume, the suggestive agency of experience...The question is, does experience act as a directive power at all, and if so to what extent? The exact limitation which is to be assigned to it, is the real difficulty in the question to my mind'. PK cannot clearly reconcile WW's differences with John Herschel's or indeed WW's earlier views from his later ones. PK believes that the mind possesses an innate faculty of cognition, which is brought into action by the ''sense to produce perfect Conceptions''.
PK would like to read his paper 'On the Elasticity of the Ether in Crystals' next Monday. However, since his paper differs with Augustine Fresnel over a certain point and WW does not approve of any differences with Fresnel's Memoir, he would be happy to discuss it with WW first.
Edinburgh - Thanks WW for his 'work which you have so kindly sent me' [probably Of the Plurality of Worlds: An Essay, 1853].
Lacock - Is not able to offer any introductions at Rome, for the only family he knows of is that of Mrs John Spedding; encloses the remarks on Assyrian inscriptions he could not find when he last wrote; has been conducting mathematical researches, thought he had found a clue to the solution of Fermat's theorem, which he discusses and which he sent on to Professor Kelland, who admired it.
Rome - JDF is pleased he decided to spend the winter abroad, and praises his Edinburgh colleagues (Thomas Henderson and Philip Kelland) who offered to fill in for him while he was absent. At Naples he saw small scale continual eruption within the crater of Vesuvius: 'I saw lava flowing and had an opportunity of comparing it in various states with the conditions of a glacier'. His findings are generally favourable to his glacier theory and he has communicated his observations in a letter to the Royal Society of Edinburgh.
Edinburgh - Thanks WW for his work on induction in answer to John S. Mill ['Of Induction, with Especial Reference to Mr. J. Stuart Mill's System of Logic', 1850]. Further to their work on revising the recommendations of the mathematics and physics section of the BAAS [see JDF to WW,12 Dec. 1849], JDF thinks it important that new experiments in the area of heat should be devised - as suggested by Philip Kelland's report 'On the Theory of Heat' (1841). JDF is undecided whether he will remain this year for the BAAS meeting, since he is very keen to embark on a continental trip. Murchison [Roderick Murchison] has written to him with suggestions on how best to spend the recent £1000 left to the Royal Society.