The year is established by the reference to Leonard Darwin’s illness (see n. 2, below).

Pritchard was headmaster of Clapham Grammar School, the school then attended by George Howard Darwin, Francis, and Leonard Darwin (see letter to W. E. Darwin, 26 April [1862], n. 2). Emma Darwin’s diary (DAR 242) records that Leonard had been sent home from school on 12 June with scarlet fever, that George returned home on 16 June, and that Francis, having come home for the weekend on 31 May, did not return to school as he became ‘feverish’ on 2 June.

Pritchard, whose main interests were mathematics and astronomy, was also interested in botany, having at Clapham, ‘one of the finest fernaries in England’ (DNB). Although CD and Pritchard evidently corresponded on botanical topics, these letters have not been found. In his memoirs (A. Pritchard ed. 1897, p. 60), Pritchard recalled that George Darwin had, while a pupil at Clapham, asked him ‘to read with him certain portions of his illustrious father’s book on The Fertilisation of Orchids.’ He continued: ‘More than gladly I did as he desired, and in due time we succeeded in fertilising and ripening the seeds of Oncidium Papilio; but we did not succeed in our attempts to induce the seeds to germinate, as his father challenged us to do: the necessary environments were wanting.’ Pritchard left his post at Clapham Grammar School in 1862, and moved to Freshwater on the Isle of Wight (DNB).