IXDKX. 



377 



Field of view, extent of, 261. 

 ,, Flatness of, 64 ; 68-78. 



,, ,, testiugthe, 168-169. 



Flatness of the field of view, 64 ; 68-78. 



testing the, 168-169. 

 Focal length Definition, 1-2. 



,, arid Angle of Aperture, 99- 



101. 



,, determination of, 181-183. 



, , optical power dependent upon, 



271. 

 ,, conjugate Focal lengths, 8-9 ; 



18. 



,, of a system of lenses, 8. 



,, of Objective-system, 27, 34. 



,, of refracting systems, 18, 33. 



Focusing, 116-117. 



Frey (H.), improved Revolving-stage, and 

 method of sealing, 285. 



Gauss (C.F. ), his exposition of the laws 



of Refraction, Setseq., 24. 

 Geissler's moist chamber, 280. 

 Globules, Oil, in water, 202-206. 

 Glycerine as preserving medium, 282. 

 Goniometer, the, 294-295. 

 Goring, application to Microscope of 

 Herschel's distinction between 

 Defining and Penetrating power, 

 91. 



,, on Illumination, 104 (note}. 

 Grammatophora marina, 136, 138. 



,, subtillissima, 137, 138. 



Granules, Reflexion of light by, 236-239. 

 Gunnera scabra Ruiz et Pav., example of 

 polarisation, 371-372. 



HARTING, his erroneous statement that 

 irregularities of Centering 

 are magnified as much as 

 the object, 84. 



,, his measurements of wire- 



gauze, 129 (note). 



,, method of drawing, 299. 



,, method of testing Chromatic 



Aberration, 159. 



,, proposed standard of unity in 



micrometric dimensions, 293. 



,, on illumination, 104 (note}. 



,, on Image distortion, 69. 



Harting, on Limit of Discrimination, 



142 and note. 



Hartnack's Analyser, 315. 

 ,, Eye-piece, 45, 50. 

 ,, and Prazmowski's Polariser, 



309. 



,, Stand, 122. 



Helmholtz on Limit of Discrimination, 



142, and note. 



,, on Stereoscopic effect of 



binocular Microscopes, 225 

 (note}. 



Herapathite crystals in polarisation, 310. 

 Hermetic sealing of objects, 283. 

 Herschel's distinction between Defining 



and Penetrating power, 91. 

 Hipparchia janira, 133, 138. 

 Holosteric or solid Eye-piece, 44-45. 

 Huyghens' Eye-piece, 35-42. 



Illumination, 103-115, 268-271. 



,, apparatus for, 118, 119. 



,, oblique, 110-111 ; 247-251. 



with reflected light, 111-115. 

 ,, with transmitted light, 104- 



111. 

 ,, erroneous ideas of influence 



of, 104 (note). 

 Image-distortion, 64 ; 68-78. 



,, distinguished from cur- 



vature, 71. 



,, elimination of, 72. 



Images of wire-gauze as test-objects, 127- 



182. 



Interference phenomena, 226-247. 

 Inulin granules, example of polarisation, 

 372. 



KELLNER'S Orthoscopic Eye-piece, 44. 

 Krafft's Periscopic Eye-piece, 44. 



LABELS for objects, 287. 



Lamps used in determining Angle of A per - 



ture, 173-177. 



Lantern Microscope, the, 267. 

 Lateral displacement of coloured objec- 

 tive images, 52. 



Layers, alternate, solid, and aqueous, 221. 

 ,, dense and soft, elevations and de- 

 pressions as opposed to^ 221-222. 



