376 



INDEX. 



Crystals, action of anisotropic crystalloid 



bodies, 319-341. 



,, action of two superposed crystal- 

 loid bodies, whose planes of 

 vibration intersect obliquely, 

 341-349. 

 ,, of amylodextrine, example of 



polarisation, 372-373. 

 Herapathite, 310. 

 Curvature of the Image-surface, 169. 



,, , ; Image-surface, influence 



of Curvature of refract- 

 ing surfaces upon, 75- 

 78. 



Field-of-view, 64-65, 260. 

 ,, ,, Field-of-view, Image-dis- 



tortion, so-called, 69- 

 70. 



,, ,, Field-of-view, distin- 



guished from Image- 

 distortion, 71. 



,, ,, Field-of-view, elimina- 



tion of, 72. 



,, ,, Field-of-view, in con- 



nexion with determin- 

 ation of Magnifying- 

 power, 178. 



Cylinder-diaphragms, 120. 

 Cylinders, Hollow, 206-217, 349. 



DEFINITION, Power of, 148, 149. 

 Determination of Angle of Aperture, 



172-177. 



,, Magnifying power and 



Focal length, 178- 

 183. 

 Cardinal points, 184- 



188. 



Diameters, equal, objects with, 363-365. 

 Diaphragms, 120. 



Dicatopter, Hagenow's, for drawing, 298. 

 Diffraction in connexion with delineation 



of fine structures, 226-236. 

 Difiractional action of Aperture of lenses, 



102-103. 

 Discrimination, testing absolute power of, 



126-127. 

 ,, testing relative power of, 



140-147. 

 Distance. Set " Focal," " Object." 



Distortion, Image, 64 ; 68-78. 



,, ,, distinguished from Cur- 



vature, 71. 



,, ,, elimination of, 72. 



See "Aberration," "Curvature." 

 Drawing of microscopic objects, 296-303. 

 ,, photomicrographic, 303. 



ELASTICITY, axes of, determination of, 



330-341. 



,, ellipsoid orsurface of, 31 9-323. 



,, ,, phenomena of po- 



larisation in relation to, 



323-330. 

 Elevations and Depressions, as opposed to 



dense and soft' layers, 221-222. 

 Eye, Chromatic Aberration of, 166-167. 



34-49. 

 ,, fluctuations in magnifying 



power of, 37. 



,, Spherical Aberration in, 62. 

 ,, correction of Aberration in, 



72-75. 

 Eye-piece, aplanatic and orthoscopic, 



43-45. 

 ,, Campani's (or Huyghens'), 35- 



42 ; 74 ; 78. 

 Erecting, 45-46. 

 error of supposing that com- 

 bined action of Field-glass 

 and Eye-glass compensate 

 defective Achromatism of 

 Objective, 161-167. 

 ,, for elimination of distortion and 



curvature, 72. 



Holosteric or solid, 44. 

 ,, Ramsden's, 42-43; 74 ; 78. 

 ,, Spectral, 47-48. 

 micrometer, 179-181 ; 182. 

 Eye-point, the, 40-42. 

 Eyes, care of the, 273-274. 



FARRANTS, preparation of glycerine re- 

 commended by, 282. 

 Field of view, Brightness of, 84-90. 

 ,, ,, Curvature of, 64-65 ; 260. 



,, ,, Curvature of, in connexion 



with determination of 

 Magnifying-power, 178. 

 ,, ,, determination of diameter of, 



180. 



