204 
INDUX. 
Sorliy. pclro;: . npliir niKTi-M-i>|-r, 7 
Sorei. measurement o( refractive indicc-. ;is. \'.:\. 
Southall. coometrical optics, 10; Smith-llclmholtz 
equation. 15. 
Sousa-Brandno. device for rotation of nicols. 58; dis- 
penrion of quart*. 101, 112; graphical p'tit, 1.51: 
inenMiri-tnrnt of optic axial ansle, I'.M; refract i\ c 
index indicaioi-. '.'7 
Spertruiii, secondai 
Sph"rical abornition. 21, 40. .51: rhrnmtitir difference 
of, .13; correction for. 33: for :i sim-lc spherical 
surface, 21; for points near the axis. 2<i; in simple 
lenM-s. 24; of iil>lii|in> rays, 21; overcorrectcd, 
. rimary. 51; proper, 21; Meowlvjr, ftl; undcr- 
mrn-'tcd. 
Spherical ovcrcorrcct ior 
Sphcrica 1 undcm irrrct ic > 
.spherical xoncs, 2" ">1 
S|iii(:. microscopy, 111; correction of objectives 51. 
microtfcope. 12. 
Stage, universal. 17."'. 
StcreographSc projection, 0:1,64,65,66,67. 
Stutter plate. 137. 145. 
SulisMKe, microscope, 12. 
Tangent rondition. 21. 
Tanxentiul pl:uio. astignuitiMii. L".'; si nu condition, 28. 
Telescope. 30. 
Tertach, d'tiTinin:ition of opticn! character. 7S; nn-:\<- 
unMiu-nt D.'bin'fnnRpncc, 114; measurement of optic 
axial nnnlr, 173; ocular for measurement of optic 
axial anele. l.V'l. 
Tent objeet-t, 51. 
Thompson, polarizing prism. .":, 54, .5.5, 60,62. 
Thouli-t. determination of refractive index. !I2. 
Topax. optic axial angle of. 194, 196, 197, 198. 
Total refractoim-tiT. W. 100. 
Traube, H., quarter undulation plate. 13.5, 137, 145. 
Twinned plate of elenite. 63. 
Tmne<l (|iiartz plate. f<3. 13. 
Twinned quart* VM-<lne, 63. 
I'lilis. niea.sur.-iiient of in>(i<- atial angle, 191. 
irriM-lii-.n. eliromatie. 31. 
1'nivef-il -t:ie ffl. 173, 17.5, 177: ineasurcinonts with, 
1'.'7; methcKl.s for iiieaMireinent of optic axial an-.-le. 
in 
I'pper nicol, rotation of, 141. 
t'seful maznilieation in microscope. 47. 
Vernier", on mirrox'opc stage. 61. 
\ ila. ine.iMireiiient of refra<'li\ -e index. 07: dim t IIIIM-:- 
iiieineiit of refractive index, !*. O 4 .'; iin*a>ureinenl 
of optic axial angle. 1113 
Voigt, internal coniciil refraction, 17^ 
\V-ilker, measurement of l>irefringence, 103. 
\Vallerant. iiie.isurement of optic axial angle, 175; (odd 
refr.ii-loriiet.-r. KNI. 1!3. 194. 
We'litc, Amman, (sraduiili'd. IU1, 102; oom!>ination . 71 , 
7.' 7.'!; double e.iin!iin:ttion, 134' Kvans, enidualeil, 
101; l/<-i>-i eradu-ited, 101. Siedentu|>f, tintduated, 
101; Wright, ur.iduated. Ml 
;ilate. l>i-quartz. T.'.l, l|n, 11.5, Kti; twinned 
quartz, 145. 
Wi-ier.strjw.*, con:*tniction for refracted r:i\~ .1. 
\\ein-ir-hi-nk, rotation of upper nicol, 141. 
\\ertheim.colorscale, 111. 
Wiedemann, measurement of birefringence, in:]. 
Wright, A. .dark ground illumination, 95; mier< 
10. 
Wright, F. K., adjustment of refracto-netor. 100; arti- 
li<'i:illy twinned quartz plate, 136; bi-quartz wedge- 
plate, 63, 139; combination wede, 72; coonlinate 
micrometer ocular, 155; determination of optical 
eh'iracter, 78,81; double combination wedge. 134: 
double-screw micrometer ocular, 15.5; graduated 
wedge, 101; graphical plut, 1.51; measurement of 
optic axial angle, 173; rotation of plune of polariza- 
tion, 76; rotation of upper nicol 141 
Wulff . projection plat, 64, 154. 176, 189, 200. 
\\fdfing, axi'tl angle apparatus, 194; di>per-in ,.f 
quartz, 112; Mallard const:ml . 1.51 ; Mikroskopiwhe 
Physiographic, 9, 10, 69, 149; refractive index 
Canada balsam 91. 
7.-i" apochromat. 54, 5.5. 
/enithal perspective projection, equations for, 64. 
/irkel, refractive li(|iiiil- 
ERRATA. 
Pace 9, line 1.5. add "I-e* Miner.-'ux des Hoc) 
Mirhel-iy-vy :uid l.ai-nn\ 
10, Utii-n lin-s _'x :.nd 2'.l. add "Hohr. M. v., 
Die Hil'lerzi-ugung in optischcn In.-t rumen- 
ten. I9t)4." 
23. I 2l>. read "I"" inste.til of "A'." 
.'W. I. 17. read "achromatic" instead of "chro- 
matic." 
57. I. 1 of footnote, read "IfiO" instead of ' 
1 2 of footnote, niid "1910" im>tead .f "\'.m ." 
64, I. 1 of footnote, read "Amer. J.ur. S<'i." in- 
Htead of "this Journal " 
M.I. 2 of foot not 'instead of "qS93." 
1 of f.,lmite. r-.id "10113" inxtead of "l02 " 
I 7 rf footnote, read "722" instead of "772." 
W.I. loff<tnole. read "Wl" instead of ' 
05. I. .5 <.f footnote, read "385. 1891" in-t.ii<l .f 
"38.5. I 
5. l.rffootDote. re.id' IVH" l-i-t- ..I of I 
VK, |. 4 of footnote, ri-.i<l "nxliile" instead of 
"Mlltide." 
Page 98, I. 9 of f 1 x)tnot;-, read "4.5, l.vsy" in-teail of 
"45. ' 
98, !. 11 of footnote, read "4;), iv.u" instead of 
"411. 1S1HI." 
HI. I. 5 of footnote, read "6. 143, 1883; 7. 43, 
1884" instead of 7 . B7, I*M 
102, 1. 5of footnote, read "1891" instead of "1892." 
112,1. Ill, n-ad "reference" inst,>ad of "referi" 
114.1. lof footnote, read "I'.llli" instead o' "1911." 
11.5. I. 3, read "elliptic" instead of "ellipsoidal " 
141,1. 2 of footnote, read "JO, 198, Ittlll" instead of 
SO. 1910." 
41. I. 13 of f(x)tnt>te, read "190&" instead of 
' 1'MO." 
147. I. 2 of footnote, read Iv'i'.i" in-tead of "ISW." 
ll'.i. I. I of footnote, read "24" instead of "14." 
1.52. I. .5 of footnote, read "I It 
m-te.id of "IS'.M; 16. 1SI' 
I.5.5. 1 1 of fmiinote, reai I "2tM" in.-te:id of "(17. " 
1.5li. I. 7. ins'i( "angle" aft<-r "optic 
17.', I li from U.tlom, read "//i" in-tead of "//." 
