Board of Trade, the, its superintendence of lighthouse-boards, 55. Borda, the mathematician, his reflecting apparatus, 71. Boulogne, referred to by Pliny and Ptolemæus, 30; its early history, 30; the Tour d’Ordre of, described—_See_ Tour d’Ordre. Brick-making amongst the Romans, description of, 40, 41. Buffon, the naturalist, his suggestions for lighthouse illumination, 77. Buoys, as aids to navigation, 270; various kinds of, 273; modes of lighting, 274; how shifted, 275. Caligula, the Emperor, his erection of the Tour d’Ordre at Boulogne, 30. Calf of Man, double lights at, 76. Capio, pharos at, referred to by Strabo the geographer, 14. Capreæ, island of, pharos on, referred to, 13. Carcel, the engineer, his efforts in lighthouse illumination, 70. Carcel lamp, the, described, 80. Carr Rock, erection of a beacon on, by Mr. R. Stevenson, 168. Catoptric system, the, of illumination, described at length, 71-77. Caylus, the Comte de, his demonstration concerning the Rhodian Apollo, 44. Champollion, his account of the building of the pharos of Alexandria, 18. Chares, the sculptor of the Colossus of Rhodes, the story of, 48. Chevreau, Urbain, his reference to the Colossus of Rhodes, 44. Chrysorrhoas, lighthouse on the, described by Dionysius of Byzantium, 13, 14. Claudius, the Emperor, at Boulogne, 13. Colossus of Rhodes, the, fabled magnitude of, 43; was it ever a beacon-light? 44; described by Pliny and Philo, 47; referred to by Lucius Ampellius, 47; the authentic facts concerning, 47, 48; its sculptor’s career sketched, 48. Colour, as a source of distinction between lights, 76, 77. Condorcet, the philosopher, his suggestions for lighthouse illumination, 77. Cordouan, the first lighthouse at, 213, 214; the second, described, 214; the present structure, history of, 214, 215; described, 216-218; M. Michelet’s account of, 218-221; its illuminating apparatus, 221, 222. _Cornhill Magazine_, quoted, 277. Crusius, Martinus, story of the Alexandrian pharos quoted from, 26, 29. Darling, Grace, the story of, 280, 281. Delavigne, Casimir, the poet, quoted, 224. Dionysius of Byzantium, his description of a lighthouse on the Chrysorrhoas, 13, 14. Dioptric system, the, of lighthouse illumination, described in detail, 77, 78, 84-87. Double lights, the, of the catoptric system, how exhibited, 76. Dover, early history of the castle, 38; the tower, its present appearance described, 38-40; its history sketched, 41, 42. Dubhe-Artach Rocks, the, described, 208; proposed lighthouse on, 209. Dungeness, the red light at, 132. Eddystone Rocks, the, position of, described, 108, 109.