Principles of Geometry

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. Erratum. In Ex. 9, p. 175, instead of by taking three positions of P upon p, read in general, by taking three positions of P upon the real line p through the intersection of the two given lines, so chosen that the corresponding points U, V, W are in line.