187_b_. The Uppermost Bridge over the Maïenreuss 375 187_c_. The Bridges over the Maïenreuss, near Wasen 377 187_d_. Windings of the Line near Wasen 378 188. Contrasts of Light 380 189. Rays 382 190. Diagram 383 191. Telescopic Appearance of Jupiter and Satellites 384 192. Diagram 386 193, 194, 195. Diagrams 388 196. Diagram 389 197. Polemoscope 390 198. Apparatus for Ghost Illusion 391 198_a_. The Ghost Illusion 393 199. Illusion produced by Mirrors 394 200. A Stage Illusion 395 201. View of Venice—Reflections 396 202. Refraction 397 203. Diagram 398 204, 205. Diagrams of Crystals 400 206. Diagram 401 207. Diagram 403 208. Diagram 404 209. Polariscope 406 210. Section showing Polarisation 407 211. Iceland Spar, showing Double Refraction 407 212. Diagram 408 213. Diagram 410 214. Diagram 412 215. Portrait of Professor Kirchhoff 416 216. Diagram 417 217. Newton’s Experiment 418 218. Bunsen’s Burner on Stand 421 219. Spectroscope with one Prism 423 220. Miniature Spectroscope 426 221. The Gassiot Spectroscope 427 222. Browning’s Automatic Adjustment of Prisms 429 223. Apparatus for Spark Spectra 430 224. The Sorby-Browning Micro-Spectroscope 433 225. Section of Micro-Spectroscope, with Micrometer 434 226. Diagram 435