[RNeff]

http://www.openculture.com/ has many lists of free books, audio, movies, images. Project Gutenberg: www.gutenberg.org Also look at https://www.forgottenbooks.com/en

and, of course, archive.org which has the book you mentioned: https://archive.org/details/BreakthroughAnAmazingExperimentI....

The Library of Congress and the Smithsonian have huge digital collections.