Dated by the relationship to the letter from E. A. Darwin, 20 June [1862].

Thomas Carlyle wanted to borrow a book from the library of the Museum of Practical Geology, Jermyn Street, London, where Trenham Reeks was registrar, librarian, and curator (Post Office London directory 1861, p. 59). Erasmus had sought CD’s help on Carlyle’s behalf (see letter from E. A. Darwin, 20 June [1862]).

Roderick Impey Murchison was director of the Government School of Mines and Museum of Practical Geology, and director-general of the Geological Survey of the United Kingdom, all of which were located in the same building in Jermyn Street, London (Post Office London directory 1861, p. 59). The rules of the library stated that ‘under no circumstances’ was any book ‘allowed to be taken out of the building’ (White and Newton 1878, p. [iii]).

Erasmus enclosed CD’s note in a letter to Carlyle dated 23 June 1862 (National Library of Scotland, MS. 1768: 34–5), for use as an introduction to Reeks. Carlyle in turn gave the letter to Joseph Neuberg, who was assisting him with the research for his life of Frederick II of Prussia (Carlyle 1858–65). At the top of the letter Carlyle wrote: ‘Erasmus Darwin Esq^r.— in helping me (T. Carlyle)’; at the end of the letter he added: ‘If M^r Reeks would extend his charity to M^r Neuberg on my behalf?— | T. C.’