Zetetic Astronomy: The Earth Not a Globe or simply Earth Not a Globe is a 430-page book written in 1881 by Samuel Rowbotham, under the pseudonym "Parallax". It was based in a 16-page pamphlet written by him in 1849, and was an expansion for it. It is the basis for most the flat earth theories supported by the Flat Earth Society.
This book, in which he lays out his world system, went through three editions, starting with a 16 page pamphlet published in 1849 and a second edition of 221 pages published in 1865. Finally in 1881, Rowbotham published a third edition which had expanded to 430 pages. The entirety of Zetetic Astronomy: Earth Not a Globe is available online at Sacred Texts