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This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it. This work was reproduced from the original artifact, and remains as true to the original work as possible. Therefore, you will see the original copyright references, library stamps (as most of these works have been housed in our most important libraries around the world), and other notations in the work. This work is in the public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work.As a reproduction of a historical artifact, this work may contain missing or blurred pages, poor pictures, errant marks, etc. Scholars believe, and we concur, that this work is important enough to be preserved, reproduced, and made generally available to the public. We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant.

An Unabridged Printing, To Include Over 100 Figures - Chapters: The Parallel Postulate, And The Work Of Saccheri, Legendre, And Gauss - The Work Of Bolyai, Lobatschewsky, And Riemann, The Founders Of Non-Euclidean Geometries - The Hyperbolic Plane Geometry - The Hyperbolic Plane Trigonometry - Measurements Of Length And Area, With The Aid Of The Infinitesimal Calculus - The Elliptic Geometry - The Elliptic Plane Trigonometry - The Consistency Of The Non-Euclidian Geometries And The Impossibility Of Proving The Parallel Postulate - Index Of Authors - Comprehensive Subject Index

A reissue of Professor Coxeter's classic text on non-euclidean geometry.