- § 388. Metrical geometry presupposes projective or descriptive geometry
- § 389. Errors in Euclid
- § 390. Superposition is not a valid method
- § 391. Errors in Euclid (continued)
- § 392. Axioms of distance
- § 393. Stretches
- § 394. Order as resulting from distance alone
- § 395. Geometries which derive the straight line from distance
- § 396. In most spaces, magnitude of divisibility can be used instead of distance
- § 397. Meaning of magnitude of divisibility
- § 398. Difficulty of making distance independent of stretch
- § 399. Theoretical meaning of measurement
- § 400. Definition of angle
- § 401. Axioms concerning angles
- § 402. An angle is a stretch of rays, not a class of points
- § 403. Areas and volumes
- § 404. Right and left

The Principles of Mathematics was written by Bertrand Russell, and published in in 1903. It is now available in the Public Domain.