130 Prof. F. L. 0. Wadsworth on the 



first four, and these are designated by S^, S_, S , S_, S 



S_, and S^^, S^^ respectively. 



Table I. 





—: 





•^" 















8 



. 











'^1-^ 



1 



i. 



'! 



-ill 

 II 





+ 



c 

 -9 tan 

 X cos 





4ii 



4 i 





+ 



-f 



CO 



1 











i-\ 





T-H 















'^^ 





^ 













o 



... 



2000 



0-000 



2-000 



9000 



1000 



QO 



2-000 



•000 i 



5 ... 



1-981 



-0076 



1-988 



9-023 



+ •928 



11-35 



2-011 



-1754 



10 ... 



1-925 



-0306 



1-954 



9093 



+ •709 



5-58 



2-046 



-355 1 



15 ... 



1-834 



-069 



1-899 



9-213 



+ •341 



3-61 



2107 



-545 



20 ... 



1-713 



-125 



1-823 



9-389 



--181 



2-58 



2192 



-750 



25 ... 



1-566 



•197 



1-728 



9-631 



—•867 



1-94 



2-320 



-981 ! 



30 ... 



1-399 



•289 



1-616 



9-952 



-1-732 



1-50 



2-488 



1-244 1 



35 ... 



1-220 



•402 



1-490 



10-373 



—2-794 



1-17 



2-711 



1-555 



40 ... 



1-036 



•539 



1-353 



10-93 



-4-086 



■913 



3010 



1-935 



45 ... 



•854 



•707 



1-207 



11-66 



—5-657 



-707 



3414 



2-414 



50 ... 



•678 



•913 



1056 



12-64 



-7-573 



-539 



3-976 



3045 



55 ... 



•518 



1^170 



-902 



14-01 



-9-955 



•402 



4-783 



3-919 



60 ... 



•375 



1-500 



•750 



1600 



-13-000 



-289 



6-001 



5-196 



65 ... 



•254 



1-944 



-601 



1906 



-17-07 



•197 



7-965 



7-218 



70 ... 



•157 



2-582 



•459 



24-24 



-22-89 



•124 



11-47 



10-78 



76 ... 



-084 



3-515 



•326 



34-39 



-32-87 



-067 



18-79 



18-15 



80 ... 



-035 



5-585 



•203 



60-20 



-50-26 



•031 



38-92 



38-33 



85 ... 



-008 



11^386 



-095 



181-5 



-102-4 



-008 



143-2 



142^6 



90 ... 



•000 



00 



-000 



X 



oc 



•000 



00 



00 



In order that the points S' to S^^ shall correspond to the 

 same spectral images for each of the various mountings we 

 must choose the values o£ ^ and i so that we always have 



(sin d — sin i) = constant 

 for any given point S. We therefore have 



(29) 



For the points 



S' 





S" 



g/// 



s- 



Case A— Ao .. 



. ZA = 5° 





15° 



30° 



60° 





^A = 0° 





0° 



0° 



0° 



Case Eo 



.^Eo = 5° 





15° 



30° 



60° 





«Eo=0^ 





0° 



0° 



0° 



For Case C... 



.d=-i 











.*. 



(sin Oj^~ 



sin / 



a)=- 



■ 2 sin i^. 





and w^e therefore have for i^ [to be used in (18a)] 



_^c I 2° 30'; 7° 26', 14° 29\ 25° 40^. 



