Charles Darwin’s works are online … free, courtesy of University of Cambridge:
This site contains Darwin’s complete publications, thousands of his private papers, the largest Darwin bibliography and manuscript catalogue and hundreds of supplementary works: biographies, obituaries, reviews, reference works and much more.
Almost all is online only here: such as 1st editions of Voyage of the Beagle, Zoology, Descent of Man, all editions of Origin of Species (1st, 2d, 3d, 4th, 5th & 6th); manuscripts & papers: Beagle Diary & field notebooks, Journal, transmutation notebooks and Autobiography.
Forthcoming: editions, translations, introductions & manuscripts.
New! Audio book of Darwin’s Beagle diary here.