Darwin Correspondence Project,

Staff of the Darwin Correspondence Project, beginning in 1974, systematically assembled these copies of original letters held in both institutional and private collections around the world. Beginning with the largest single collection of Darwin correspondence, the 9,000 letters in the Darwin Archive of the Cambridge University Library, England, project staff by 2006 had located and had photocopied 6,000 additional letters. As new letters continue to be found, photocopies of them will be added as well.