Reflexion of Light from Iceland Spar. 



Table XI. — Observations with Polished Face. 



r'. Mean /. r. Mean r. E'. Mean E'. E. Mean E. 

 187-129° 43-050° 133 '041° 41-621° 



137-404 42-727 133-269 41-319 



137-357 43-080 133 '421 4l'536 



137-297° 42-952° 133 '244° 41-492° 



137307 43-104 133 331 41-556 



137-075 42-875 133-267 41-332 



137-242 43-062 133 135 41-474 



137-208 43-014 133-244 41-454 



137 031 43-289 133-121 41-617 



137-401 43-097 133-556 41-745 



137-336 43 009 133-455 41-479 



137 256 43-132 133*377 41*613 



41 -298 



137-155 



42 -890 





133 035 



41 -366 



137 '382 



42 -984 





133-000 



41 -231 



137 'S 



!68 



42-937 



133 017 



137-346 



43 -040 





133 -441 



41 -621 



137 -255 



43 -091 





133 -299 



41 -812 



137 425 



42-921 





133-319 



41 -452 



137 -342 



43-017 



133 



•353 



137 -106 



43 -400 





133 -485 



41 -869 



137 -047 



43 -257 





133-474 



41 -910 



136-869 



43 -147 





133 -333 



42 -054 



137 -014 



43 -165 





133-525 



42 -127 



137-089 



43-347 





133 -562 



41 -712 



137 155 



43-124 





133 250 



41 -549 



137-264 



43 -055 





133 -381 



41 -886 



137 -078 



43 -214 



133 "430 



137 -667 



42-809 





133 -612 



42 -048 



136-954 



42 -938 





133-489 



41 -665 



137 020 



42 -821 





133 -366 



41-834 



136 -992 



42 -977 





133 -419 



41-697 



137 -064 



43-104 





133 -228 



41 -681 



136 -730 



42 -859 





133 124 



41 -704 



137 045 



42 -731 





133 -266 



41-424 



137 179 



42 -895 





133 -216 



41 -719 



137 -006 



43-075 





133 -217 



41-636 



41-628 



41-872 



137 073 42-912 133-326 41-712 



The mean of the 960 observations of Table XI gives — 



r r = 137-168°, r = 43-031% 



B/ = 133-321°, R = 41-656°. 



Thus I = 87-488°. 



But Table IX gives for the mean value of I — 



I = 87-654°, 



a difference from the above of 0-166. 



