33. Four harmonic lines
34. Four harmonic planes
35. Summary of results
36. Definition of projectivity
37. Correspondence between harmonic conjugates
38. Separation of harmonic conjugates
39. Harmonic conjugate of the point at infinity
40. Projective theorems and metrical theorems. Linear construction
41. Parallels and mid-points
42. Division of segment into equal parts
43. Numerical relations
44. Algebraic formula connecting four harmonic points
45. Further formulae
46. Anharmonic ratio
PROBLEMS
CHAPTER III - COMBINATION OF TWO PROJECTIVELY RELATED FUNDAMENTAL FORMS
47. Superposed fundamental forms. Self-corresponding elements
48. Special case
49. Fundamental theorem. Postulate of continuity
50. Extension of theorem to pencils of rays and planes
51. Projective point-rows having a self-corresponding point in common
52. Point-rows in perspective position
53. Pencils in perspective position
54. Axial pencils in perspective position
55. Point-row of the second order
56. Degeneration of locus
57. Pencils of rays of the second order
58. Degenerate case
59. Cone of the second order
PROBLEMS