2O2 
1NDKX. 
B, rotatory p >Urii:ition of quartz, 131; t -\' 
U>ok, optics, 10. 
Dufet, optical con-lant<, 112. 
Dupurc.TraitedcTcchn.Min.ct I lo.l.lli'. 
1 1" .Kquixal.-nt focal length 1 . 19. 
K mergence port. 34. 
1 Imergence pupil. 31. 
l-'.mpty magnification in microscope, 47. 
Lnt ranee purl, 34. 
Km ranee pupil 
Kqual surfnct- projection, 63. 
Kquator anzle projection, 117 
Kquidistant projection, f>ft,67. 
Kquivident focal length, 19,50. 
Equivalent planes, 19. 
Kqiiivalent projection, f>3. 
Kuler, mechanical <|iiadruture, r.ii. 
Evans, determination of refractive index. '<}: siun of 
reaction, M; universal methods, 17">; wedge, 101, 
1".'. 
i:\it port. 34. 3.V 
Kxit pupil, 34.3V 
Kxner. microrefractomeler. H.V 
Kxtinction angle, 7, 8, 69, 115; methods for measure- 
ment of, 132. 
Extinction direction, 68. 
Eye-circle, 3.">; diameter of, 3\ stop, 78. 
Kye-piece, 11, 30: Abbe compensating, 33; chromatic 
undercorreetion in. 32; chromatic overeorrection 
in, 32; compensating, 52; function of, 30; Huygens, 
52; micrometer, 52; Ramsdcn, 52. 
Eye-point, 35. 
Ferraris, CI., geometrical optics, 10. 
Pedorow. determination of refractive index, 176; dis- 
persion of optic axes, 82; graphical plat, 151; me.i- 
uromentof birefringence, 176. 191; mica compara- 
tor. 103: stereographic projection. 61: universal 
stage. 117: universal stage, methods, 174, 175, 177, 
I7'.. ISO. 184. 185. 18P.200. 
1'elilspars, plagioelase. extinction angles of, 132. 
I enner. acknowledgment to, 9. 
I .-rro, extinction nnglex, 191. 
I it-Id of microscope, 42. 
Field of view diafram, 34. 
Figures, formation of interference, 1 17. 
r, lUuldc color seal- 
riett.apertometcr. MS, 149. 
Focal length, equivalent, It); of two component lens 
system, 19; principal, 17, 
Focui distance, 19. 
Fouiiue, character of principal zone, 71. 
Fowle. energy in sun spectrum, 109. 
1 re-m I, rule of, 68. SO, 154. 107. 168, 176, 11H, _'<M>; 
formula* for rotation of plane of polarization, 76. 
I, measurement of birefringence, 103. 
Pnea objective, 54,55. 
CiaoM equations for paraxial rays, 14. 
< .. rmain, on projections, 63. 
Gladstone's law, 92. 
Clan prism, 55.62,71. 
(inomonic meridian projection, 64; projection, ('..;, r,|, 
65.66.67. 
(ioldschmidt. on projei-tioi 
' irabham. oblique illiiiuiii.it i' .11, 
< .rad'ial. il hemisplii re, Nikiiin 
Granulnritv limits in petroKruphic niitToscopic work, 
8.10,11. 
Grctschel, on projections, 03. 
Half hude apparatus, 128,120. 
Half-sbado plat*. Nakn 
knmura. 139. 
Harker, extinction anjIeH, 191. 
HastinKK, C. 8., iceometrical optics, 10. 
Heath, It. S . i-conictrical uptu-.. In. 
HiH-ht, measurement of refmctive indices, 08. 
Helmholz. ei|uation. 15. 
Hemixpherc. Ainchinow, graduated. 171, |-'i-dnr>>w 
Klaai. 176; Nikitin. graduate*!, 166; Wright, 
CradoaUKl, 174 
Hiiiiinelbnuer. refractive index of liquid*, 08. 
HlnwaUch, dispention of quart*. 112. 
I lockin. derivation of sine condition. 10, 27. 
HotcbkiM, refractive index dutorminntion, 1'7. 
Huygens, construction of wave-fronts. 21; ocular, 58. 
lildincs, roek inineralfi, 0. 
Illumin-ition, artificial. 77: critical, ">:': dark-ground, 
.-tire of, :t:i; ol.lique, .V. 
ofobji 
Image aiu- v 
I mage formation in microMope, Abba'i derivation, 4:'. 
Imrnersii.n inelhod for refnictivc index determina- 
tion. I 
Inti-nsit.\ of Ikht, in.illicniatical forinulu for, 80,115. 
Interference color-, aliiiormal, I-'S- 
Interfcrence lieure.". device for ol>ser\ ittion of, .Vi; 
factors underlyinR formiition of, 15S, 159; forma- 
tion of. 147. 
Iris diafram, 12. 
[VW, >t -indanl c .lorimeter, 69,71; visual sensibility 
curve, 110. 
Jamin, I'.uliinet compensator, 111). 
l\alk->u.-k\ , internal conical refraction. 17*. 
Kcllnei, acknow -ledgment to, '.': condenser a|Mto- 
in. -ter, 17J; drawing for astigmatism, 29; equiva- 
lent focal length (K. F.), 19. 
Klein, lens, 171; observation of interference ligun-, 
147; quartz plate. 137. 
Kle'iieiit. DUCTOobemioa] reactions, CO. 
Kobell, plate. 111'. 
Kocnigsberger, absorption, 71; plate, 103, 134, 137, 145. 
Kraft, color scale, 103.111,112. 
Lacroix, Tx-s Mineraux iK's Uocties, 173; observation 
of interference figures, 147. 
Lasjrange-llelmholz ecjuiition, 15 
l.a Hire, projection of, 68. 
l.andolt-Mornstein, tables of, 85, 112. 
Lane, A. C., measurement of optic axial angle, 1'Jl, 1!>J. 
Larsen, acknow ledgment to, 9. 
I i - mix, observation of interference figure, 147. 
l.aspev res. observation of interference ligure, 147. 
Lateral maunification. 15. 
l.avenir. measurement of refractive indices. 98. 
l.ei>s conden.-MT, (id; Nikitin hemisphere, 166; optical 
instruments, 10: wedge. 101,102. 
l.enk, observation of interference figure, 147. 
I.ens, Amici-Hcrtrand, 171; lormul:r, 13,14; formuln- 
fundament'il for central rays, IIS; Klein, 171; 
refraction through a, 15 
Lens system, aplanatic. Abl>e's definition, 2."*; focal 
|eni:th of two eoni|>i>nent, 1'J; optical eleinent-, 
of micniMeope. 4!l. 
l.iebisch, absorption and pleoehroism, 71. 
Light, equal ions for intensity of, 118-127, 130, i 
vibration of. llti. 
Light, threshold value of. 127. 
Lippich. F., geometrical opiics, 10. 
Liquids, refractive. 'JT.i'v 
Ixjwry, projection of. 06. 
Lummer, geometrical optics, 10; imago formation in 
microscope, 43. 
Mace 1 tlo T/pinay, liabinet compensator, 101; half 
shade apparatus, 13(1. 141. 
Magnification, 11,40; Abbe's definition of, 41; angular, 
15; approximate measure for, 4 I ; chromatic differ- 
ence in, 32; chromatic differences of, 30; empty, 
47, 4M; lat'ial. l"i; measurement of, 38; normal, 
41: useful, 47,48. 
Magnilier. IJ'i. 
Mallard constant, IIS. 1 111, 172; deturmination of opti- 
cal charaeler. 7'.l. measurement of hireflin 
KM; me.i-nrenietit of optic axial angle, 150, 151, 
152. K.' 
Mains, (xilarixation of light-wa-, . 
Maseait, Hravais-Hiol compensator, 101. 
Ma-chke. determination of refractive indux, 85, 88, 
87; oblique illumination, 92,95. 
Mathematical formula for intensity of light, 115. 
Mechanical >tai:e, 60. 
Mi-chanical s\ steir . bJC tnictOMOpe, II. 
Meriili'lll anuli- |i! 
Me:-idmn:il plane, sine com lit mn, 28. 
Merin, ac-knowli'<lnment to.!': di :|XTsion of lic|uids, 
'17: graphical plat, I52; tav filter, S7; refi 
iKitiids. 08. 
Michel Levy color chart, 101, HIM, 111; comparat >r, 
KM, 111; di-jier.-ion of q'i,n/. II 1 .' !- \l ini'-niuv 
ment of optic axial nnie. 
173, I'.xi; lefiactive iinl-A indicatoi.x, 97; sharp 
focus on a point, 104. 
