INDEX. 
Abln'. apertomclcr, .">!. 172; apix-hroiiuitic objective*. 
.Vi: coinpcnxatini: definition of aplan- 
:in-m. >; image formation in microscope, 10,42, 
I'!: muiienc-il aperture, :i7. 42; ocular spectroscope, 
71; sine condition, '.'7; tot:il rcfnictometer, 97,194. 
.\|>|M>II, intensity of Holar spectrum, 109. 
\bcirat ions, chromatic, 31; spherical, mon x-liDmatie 
light. .'I. 
Absorption, 7,69,71. 
Achroiiias\ . 32. 
Achromatic objecthe-, :i:;, Hi, ">1. 
Vchromats, 49. 
Adjust merit of pctrojr.iphic mi--ni-<. >p-.-, 11, 1-', 111, Ills. 
Ahrons prism, - r >5. ' 
Ambronn, immersion BMtbod, 93. 
Amici l.-ns, 147.171. 
Amman birefractometcr, 102; wedge, 101, 102. 
Analyzer, 1 1. 
Analyzer, distortion ilue to, 53,54,55. 
Angle, optic axial, 147. 
Angle pnijeetinn, f>'i, 67. 
Angular aperture, 34. 
Annular field of view, 34. 
Angular magnification, 15. 
Anhyilrite, I til'. !,. 
Apertomcter, Abbe, 51, 14S, Hit, 172. 
Apertoineter, condenser, 172. 
Aplanatie points of a single refracting spherical sur- 
fare. 23, 37. 
Aplaiuiti.sm. Abbe's definition of, 28. 
Apochromatic objectives, 33, 50, 51. 
Apochromats, 49. 
Arago, rotatory power of quartz, 131. 
Aragonite. optic axial angle of, 194, 195, 196. 
Anms. chromoscope, 70. 
Arschinow. graduated hemisphere. 171. 
Artificial illumination, 77. 
Astigmatic difference, 29. 
\-timnatie flattening of image, 30. 
Astigmatism, 21,29,30,49,50.52. 
Axial angle apparatus, measurements with, I'.'l. 
Mahinet compensator, 101, 114, 140. 
Hack focus, 1!>. 
Beck, Conrad, 10. 
Heckc, determination of optical character, 7!l, M; dr- 
um of qu-irtz, 112; drawing table, measure- 
ments with, KM; drawing table method, 152, 153, 
154, 173; Klein lens, 171; K-nsfor interference ti 
17; line, 53, H7. 92; line method, fl:>. %: meas- 
urement of optic axial angle, I'M. 1-Vi. 157, 158, 
159, 100, 163. 164, 166. 167: oblique illumination, 85. 
I'.erquerel, refractive index determination, 97. 
Mehrens, microchemical reactions, 69. 
H-Ttin, refractive index determination, 97. 
I'.ertrand, axial angle apparatus, 173: lens, 11, 13, 50, 
K. 77. 117. MS. 171 jocular, 63, 138, 146; plate, 137. 
Hi nirol ocular, 137. 145. 
Blot, eompeMator, I01:iotat'ry |X)larizat ion of quartz, 
131; ruleof, tis.vi. l.M. Hi7. ir.s. 176.191,200. 
Mi-(|uartz wedge plate, W, 140, 145, 146. 
HirefractometiT, Amman, 102. 
Birefringence, 7, 8, 69, 101; average. 105; calcite, IT.'; 
measurement of, .5S, 102, 1(0, 104, 114; probable 
error in determinutionof, 106; quartz 112; selenite, 
111 
lii-.-ctric-1-v, dis|HT.-ion of, 82. 
Hlur cirri.-, 4(1. 
Hoekc, stereosraphic projei-lion, 111. 
Brace, dicier- ion of <|iiatiz. 1 1'J. 
Hnvai>-Biot coinpenxitm-, lul. 103. 
llravais, x-nsitive tint plate, 103. 
-lober pi-it-, 134. l:t7, 14.'.. 
Brcwfter. detiTininati-m of ery.-t:d >\ stein b\ optical 
properties, 177. 
Mrezina. plate for determining extinction angle-, 142. 
Brill, refractive indices, 98. 
Hrucke, schistiscop, 70. 
Brun, refractix-e index determination, ^.V 
Calcite, birefringence of. 112. 
Calderon, culcite plate-. 131. I3.">: ocular, 146. 
Calkin-*, refractive index of Canada bjalxum, 91. 
Cahours. refractive index determination, 97. 
Canada balsam, refractive index of, 91. 
Cap st p for obwrvHtion of interference figures, 59. 
Centering screws. 12,60. 
C^aaro. de-termination of (jptical cliaracter. 79, M. x -': 
interference crons in objective, 76, 159; mathe- 
matical formula; for extinct ion angle*, 191; mea.v 
iirement of birefringence, 113; probability of fin-i 
ing se<-tions. 190; wedge, 101, 102. 
( 'h:iracler of principal zone, 71. 
Chaulncv method, S3, 97, III. 
Chief a\. 
Cliristiamien, refractive index determination, 92,93. 
Chromatic aberration. 31, 49; correct ion of microscope 
objectives. 33; difference of magnification, 30, 32. 
"..': difference of spherical aberration. 33, 4'.': 
overcorrection, 31: ovorcorrection in eye-piece, 32; 
undereorrection, 31; undercornwtion in eye-piece, 
32. 
Chromoscopc, Arons, 70. 
Chrustschoff compensator, 101. 
Chwolson, text-bofjk, ph\sics, 10. 
( 'ircle of confusion, 33, 4!l. 
Circular polarization of quartz, 112. 
Cleavage, 71; angle, 8,69. 
Color, 7, 69; primary, 51. 
Color chart, 101: Michel-Levy. 10-vlll. 
Color scale, Kraft, 111: Newton, ins. 112. 113, 133: 
Quincke, 111; Radde, 69; Kollet, 111; Wertheim, 
111. 
Colorimeter, Ives, 69; Nutting, 70. 
Coma. 27,51. 
Combination wedge, 71,72,73. 
Comparator, Fedorow mica, 103; Michel-Levy, lol. 
111. 
Compensiiting eye-piece, 52; A bin', 3. 1 ?; ocul-.ir, - r <2. 
Compensator, Babinet. 101. 114, 140; ChrustschofT, 
101; Braxais-Biot, 101,103. 
Condenser, 11,52. 
( 'ondenser apertomcter, Kellner; Sommerfeldt, 172. 
Condenser lens, ten Siethoff, 173. 
< 'ondition for aplanntism, 24. 
Conjugate foci, 14; planes, lo; points, 14. 
Con-t int. Mallard, 14S, l!l. 
Construction of pctrographic microarope, 11. 
Convergent polarized light, 13. 
Coordinat" micrometer ocular, 155, \M, 171, \~"t. 
C'ornu, A., dispersion of minerals, 112, I'M: refractive 
index determination, 99. 
Cox-er glass, spherical al>crration due to, 51. 
Craig, on pn)jc-ctions, 6.'!. 
Critical illumination, 52. 
Cross-hairs, adjustment of, 62. 
CrxMal habit, 7, 6!l. 71. 
Crystal sxstem. determination of, 177. 
Curvatnre of field, 21.:iO. i 
C/apski. location of dinfram in microscope. 59: obser- 
vation of interferonc*- figures, 147; ocular, 171. 
Daly, mathematical formuliC for extinction anglc~, I'M. 
Dark-ground illumination, 53,95. 
Diafmm, iris, 12. 
Diafr.ims in the micmsct>|>e, ">\ 
Dick, Allan, petrogniphic micn>M-opi^, in. 
Dick, device for rotation of nicol-, ">r 
Difference- of magnification, chromatic, 3 I. 
Diffraction grating, 43. 
Dispi-rsion. chromatic. 31: of bisect rio-s, 7. li' 1 . 
of minerals, 113; of optic axes. 7, 69, 82; relative, 
Distortion. 21. :( i. 'i. ">.': ptrxluced by analyzer, 53, .V>. 
Double combination wtnlge, 134. 
Double-screw micrometer ocular, 155, 166, 175, 196. 
Drawing table, Wright , 1";. 
Draw ttilx-, 11. 
201 
