[1] See Note 1 at the end of the volume.
[2] See Note 2.
[3] See Note 3.
[4] A circle--in our case the horizon--is measured by dividing the
circumference into 360 parts; each part is called a degree. Each
degree is divided into 60 minutes, and each minute into 60 seconds.
[5] See page 113.
[6] See Note 4.
[7] See Note 5.
[8] See Note 6.
[9] See Note 7.
[10] See Note 8.
[11] See Note 9.
[12] See page 93.
[13] 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.
[14] Republished by permission from "Science."
[15] Presidential address delivered at the St. Louis meeting of the
Physical Society, December 30, 1919. Republished by permission from
"Science."
[16] From a report in The Observatory, of the Joint Eclipse Meeting of
the Royal Society and the Royal Astronomical Society, November 6, 1919.