The notebook contains dated entries from July-September 1917. It has been used in both directions. At one end is a series of undated speculations by Edison in regard to ether, light and optics, astronomy, electricity, electromagnetism, gravitation energy, and other topics. Among the numerous theorists he mentions are Augustin Louis Cauchy, James Challis, Rudolf Clausius, Albert Einstein, John Herschel, Lord Kelvin, Pierre Simon Laplace, and Georges Louis Le Sage. Several pages preceding the Edison entries have been removed from the book. At the other end of the book are notes by two unidentified experimenters pertaining to Edison's work for the U.S. Navy during World War I. These entries relate to "Splash Parallax" experiments at Red Bank, New Jersey, and include range and distance measurements for sighting of objects on Sandy Hook as viewed from the Atlantic Highlands and objects at Columbia University as viewed from the Palisades. The front cover is marked "Aether." The pages are unnumbered. Approximately 90 pages have been used. Courtesy of Thomas Edison National Historical Park.