[3] See [Note 4]. [↑]

[4] See [Note 5]. [↑]

[5] See [Note 6]. [↑]

[6] See [Note 7]. [↑]

[7] See [Note 8]. [↑]

[8] See [Note 9]. [↑]

[9] See page [93]. [↑]

[10] This has since been [translated into English] by Dr. Lawson and published by Methuen (London).

Since the above has been written two excellent books have been published. One is by Prof. A. S. Eddington, Space, Time and Gravitation (Cambridge Univ. Press, 1920). The other, somewhat more of a philosophical work, is Prof. Moritz Schlick’s Space and Time in Contemporary Physics (Oxford Univ. Press, 1920).

Though published as early as 1897, Bertrand Russell’s An Essay on the Foundations of Geometry (Cambridge Univ. Press, 1897) contains a fine account of non-Euclidean geometry. [↑]