LIST OF ILLUSTRATIONS ON WOOD. xxv 



FTG. PAG1P . 



142. Street reflectors 205 



143. Measuring the vertical height of an object 205 



144. Theoretical principle of the sextant 206 



145. The sextant 207 



146. Naval officer observing with a sextant 208 



147. Wollaston's reflection goniometer 210 



148. Gee-metric principle of the goniometer : rotatory angle of the crystal . 211 



149. Babinet's reflection goniometer 211 



150. Geometric principle of the various systems of heliostats 213 



151. J. T. Silbermann's heliostat . . . 214 



152. Foucault's heliostat 215 



153. The siderostat 217 



154. Catoptric light 221 



155. Fresnel's first lenticular apparatus : in elevation and plan 223 



156. Path of rays in Fresnel's catadioptric lighthouse 224 



1 57. Total reflection in the prisms in catadioptric lighthouses 224 



158. Fixed light of the first order and white light 225 



159. Lenticular apparatus and lamp of a first-class revolving light .... 226 



160. Section of the lighthouse at Cordouan 227 



161. The lighthouse at New Caledonia 227 



162. Holophotal arrangement 228 



163. Dioptric holophote 229 



164. Section of dioptric spherical prism . . . . * 229 



165. Stevenson's revolving light 230 



166. Application of azimu f hal condensing prisms 230 



167. Arrangement of the prisms 231 



16S. Lens at the Lochindall lighthouse 231 



169. Apparent light 232 



170. Path of the luminous rays in the small microscopes 234 



171. Magnifying glasses of different kinds 235 



172. Support for lens 236 



173. Another kind of stand for lens 236 



174. Simple microscopes 238 



175. Simple microscope with doublet. Wollaston's doublet, improved by 



Chevalier 238 



176. Compound microscope 239 



177. Path of the luminous rays in the compound microscope 240 



178. Campani's achromatic eye-piece 241 



1 79. Divergent lens 241 



180. English form of inclined microscope 242 



181. Compound microscope mounted on stuid 243 



182. Microscope used by chemists 243 



183. Nachet's inclined microscope 243 



184. Am ici's horizontal microscope 243 



185. Microscope with three tubes for simultaneous observers 244 



186. Arrangement of tubes in Wenham's binocular microscope 245 



187. Nachet's binocular microscope . . . . . . . . . . . . . . 246 



188. Photo-electric microscope 247 



