50 L. B. Tiickcrman 



or approximately since k is small and I m small compared with 2 P o 



8 ^ = i\^/ (/ "" a '/? ,y ' • • • ) (94) 



Type B 



Bravais Biplate. 



Brace Elliptic Halfshade. 



Laurent Saccharimeter Halfshade. 



For these 1=1 2 and F=I\, the difference between the two 

 halves consisting of the difference between the orders N 1 and 

 X\ of the two halves of the halfshade. Then from (14) 



— Q sin 2 (o, 1 ) sin 2 ( 1 , 2 )(cos 2 it N x — cos 2 w X\ ) 



+ /C COS2(o, l)sin2 (l,2)(cOS27rA r 1 — COS2ttA\) 



+ 5 sin 2 (1,2) (sin 2 ttA 7 ", — sin 2ttN\) 



A/ 



+ 2 Q„COS 2 (O, I ) COS 2(l,2) 



+ 2K sin 2 (0, 1 ) cos 2(1,2) 



— Q o sin2(o, i)sin2 (i,2)(cos27riV 1 -f-cos27riV 1 ) 



-f/C o COS2(o, l)sin2(l, 2)(cOS2 7r7\^ 1 H-COS2 7rA r ' 1 ) 



-\-S • • • • sin2(i ) 2)(sin27T7V 1 +sin2 7rA r ' 1 ) 

 Substituting y 2 (N 1 +N' 1 )=X, and y 2 {X—X\)=±X: 

 - +Q si n2 (°> 1 ) 



A/ 



—K cos 2(0, 1 ) 



sin 2 ir A T 



+ 5 COS2 7rjV 



sin2(i,2)sin2 7rA.V 



-f- Q cos 2(0,1) cos 2(1,2) 



+ /C Sill2(o,l)cOS2(l,2) 



+ Q o sin2(o, i)| 



— /C COS2( O, I )[COS 2 ttA T 

 4-5 sin2 7riV 



206 



sin 2( 1 , 2)cos 2 7rA.V 



