derived shadows (175—179).—Shadow as produced by two lights of different size (180—181).—The effect of light at different distances (182).—Further complications in the derived shadows (183—187).—FOURTH BOOK ON LIGHT AND SHADE.—On the shape of cast shadows (188—191).—On the outlines of cast shadows (192—195).—On the relative size of cast shadows (196. 197).—Effects on cast shadows by the tone of the back ground (198).—A disputed proposition (199).—On the relative depth of cast shadows (200—202).—FIFTH BOOK ON LIGHT AND SHADE.—Principles of reflection (203. 204).—On reverberation (205).—Reflection on water (206. 207).—Experiments with the mirror (208—210).—Appendix:—On shadows in movement (211—212).—SIXTH BOOK ON LIGHT AND SHADE.—The effect of rays passing through holes (213. 214).—On gradation of shadows (215. 216).—On relative proportion of light and shadows (216—221).
IV.
PERSPECTIVE OF DISAPPEARANCE
Definition (222. 223).—An illustration by experiment (224).—A guiding rule (225).—-An experiment (226).—On indistinctness at short distances (227—231).—On indistinctness at great distances (232—234).—The