|Publisher||Trübner & Co|
|Media type||Print (Hardback)|
|Pages||Vol. 1: 302 pp.|
Vol. 2: 294 pp.
The book details the creation and use of apergy, a form of anti-gravitational energy, and details a flight to Mars in 1830. The planet is inhabited by diminutive beings; they are convinced that life does not exist elsewhere than on their world, and refuse to believe that the unnamed narrator is actually from Earth. (They think he is an unusually tall Martian from some remote place on their planet.)
The book's narrator names his spacecraft the Astronaut.
The same title was used for a later, similar book—Across the Zodiac: A Story of Adventure (1896) by Edwin Pallander (1869–1952) (the pseudonym of UK biologist, botanist and author Lancelot Francis Sanderson Bayly). Pallander copied some elements of Greg's plot; in his book, gravity is negated by a gyroscope.