Letters to John Ward, 24 August 1839-09 February 1848 Unit ID: no. 18, 20, 22, 25, 26, 43 Date: 1839-08-24/1848-02-09
Letters to Sedgwick, Geology, 04 February 1856-24 October 1857 Unit ID: II/I-J Date: 1856-02-04/1857-10-24
Letters to Sedgwick, Geology, 06 February 1850-14 October 1865 Unit ID: II/Q-Y Date: 1850-02-06/1865-10-14
Letters to Sedgwick, Geology, 13 September 1853-18 November 1853 Unit ID: II/M Date: 1853-09-13/1853-11-18
Letters to Sedgwick, Geology, 20 April 1855-15 July 1872 Unit ID: II/CC-NN Date: 1855-04-20/1872-07-15