'This excellent observer ...': the correspondence between Charles Darwin and James Crichton-Browne, 1869-75.

Between May 1869 and December 1875, Charles Darwin exchanged more than 40 letters with James Crichton-Browne, superintendent of the West Riding Pauper Lunatic Asylum, Wakefield, Yorkshire. This paper charts their relationship within the context of Darwin's wider research networks and methods; it analyses the contribution that Crichton-Browne made to the writing of Expression, arguing that the information he provided materially affected Darwin's thesis, and that it was partly the need to assimilate this that led Darwin to publish Expression separately from Descent. The letters help to reconstruct Crichton-Browne's early research interests, and document Darwin's little-explored role as a patron. Both men are revealed within a collaborative scientific network, with each of them at various times a beneficiary or a promoter.