The Outline of Science, Vol 1 (Version 2) - J. Arthur Thomson

The Outline of Science, Volume 1 was written specifically with the man-on-the-street in mind as the target audience. Covering scientific subjects ranging from astronomy to biology to elementary physics in clear, concise and easily understood prose, this popular science work is largely as relevant today as when first published in 1922. Special emphasis is given to the principles of biological adaptation and evolution, especially how they relate to the rise of the human species from lower orders. Also included are the basics of the (then) fairly new concept of relativity and its impact on emerging scientific theories.

Since first posted at Project Gutenberg in 2006, the text of The Outline of Science, Volume 1 has consistently ranked in the "Top 100 EBooks" category.
(Summary by James Christopher)