Links to texts in the Science list with decent public-domain versions and notes about newly available translations (if any).
Aristotle, Physics
Excerpts and links to public domain versions
Nicolaus Copernicus, Commentariolus
Excerpts and links to ebook versions
Francis Bacon, Novum Organum
Excerpts and links to public domain versions
Robert Hooke, Micrographia
Excerpts and links to both public domain text versions and paid versions with illustrations
Isaac Newton, “Rules” and “General Scholium” from Philosophiae Naturalis Principia Mathematica
Complete Rules and Scholium, along with a link to a public domain version of the entire work
Georges Cuvier, “Preliminary Discourse”
Excerpts and links to the entire public domain work
Charles Lyell, Principles of Geology
Excerpts and links to public domain versions
Charles Darwin, On the Origin of Species
Excerpts and links to the 1859 version
Gregor Mendel, Experiments in Plant Hybridization
Excerpts and links to public domain versions
Albert Einstein, The General Theory of Relativity
Links to both paid and free ebook versions
Max Planck, “The Origin and Development of the Quantum Theory”
Links to the entire (brief) address