380 



INDEX. 



Objects, preparation and treatment of 



specimens, 275-280. 



preservation of specimens, 280-288. 

 See "Crystals," "Liquid," "Mem- 

 branes," "Solid," "Substances." 

 Observation, microscopic, theory of, 189- 



255. 



Oil -globules in water, microscopic ob- 

 servation of, 202-206. 

 Optical Power, 90-92. 

 Organic test-objects, 132-139. 

 Orthoscopic Eye-piece, 44, 72. 

 Oscillaricce, observation of motion of, 252. 



P ACINI'S liquid for preserving specimens, 



283. 



Periderm and Cuticle, example of polarisa- 

 tion, 372. 



Periscopic Eye-pieces, 44. 

 Photomicrographic representation of ob- 

 jects, 303. 



Pinnularia viridis, 134, 138. 

 Pipette, the, 278. 

 Plane of Adjustment, interferences in, 



240-247. 

 Plane, Focal planes, and principal plane 



of an infinitely thin lens, 5. 

 ,, Principal, of compound Refracting 



systems, 6, 16. 

 ,, Principal and Focal, of Objective 



systems, 185-188. 

 Plate, Rotating, 315-319. 

 Pleurosigma angulatum, 134, 138. 

 attenuatum, 135, 138. 

 ,, for demonstra- 



tion of diffraction 

 phenomena, 234. 

 ,, bfilticum, 136, 138. 

 Plcessl's Aplanatic Eye-piece, 43. 

 Points, Principal, of compound refracting 



systems, 6, 16. 

 Nodal, 8. 



Optical Cardinal, 9. 



determination of Optical Cardinal, 

 23 ; (in tabular form); 184-188. 

 Polarisation, phenomena of, 304-374. 



,, in relation to 



the Ellipsoid 

 of Elasticity, 

 323-330. 



Polariscopes, use of, 305. 



Polariser, the, 304-311. 



Power, Delining and Penetrating, 91-92. 



See "Magnifying," "Optical." 

 Prisms, used for drawing, 298. 

 ,, Foucault's, 308-309. 

 ,, Hartnack and Prazmowski's, 309- 



310. 



Nicol's, 305-315. 

 Pritchard's lenses, 263, 264. 

 Pseudoscopic effect in binocular Micro- 

 scopes, 223-224. 



RAMSDEN'S Eye-piece, 42-43. 

 Rays of direction, 8, 16. 

 ,, analytical determination of the 

 path of, in refracting systems, 

 9-23. 



,, determination of the distances of 

 corresponding image-points from 

 the axis in the case of any given 

 inclination of the, 24-26. 

 ,, refracted by Eye-piece, 34. 

 ,, course of, within Eye-piece, subse- 

 quent to their emergence from 

 Eye-glass, 39-42. 

 ,, means of dividing Pencil of, 48-50 ; 



223. 

 ,, in relation to brightness of field, 



84-90. 

 ,, ,, Illumination, 103- 



115 ; 247-251. 

 ,, Aperture of effective cones of, 257- 



259. 

 ,, devices for drawing which project 



the, 298. 

 ,, Polarisation of, 304. 



See "Diffraction," "Illumination," 

 "Light," "Reflexion," "Refrac- 

 tion." 



Razors for preparation of sections, 276. 

 Reflector, Side-, 113 (note). 

 Reflexions by small spheres, granules, fine 

 threads, &c., and Interfer- 

 ence phenomena thereby pro- 

 duced, 236-239. 



Interference due to, 240-244. 

 ,, in drawing of microscopic ob- 

 jects, 297-303. 



