This is an OCR edition without illustrations or index. It may have numerous typos or missing text. However, purchasers can download a free scanned copy of the original rare book from GeneralBooksClub.com. You can also preview excerpts from the book there. Purchasers are also entitled to a free trial membership in the General Books Club where they can select from more than a million books without charge. Subtitle: A Selection of Material From the Essays Submitted in the Competition for the Eugene Higgins Prize of $5,000; Original Published by: Scientific American publishing co., Munn & Co. in 1921 in 370 pages; Subjects: Relativity (Physics); Relativity (Physics); Biography & Autobiography / Science & Technology; History / General; Science / Gravity; Science / Physics; Science / Relativity;