H. S. Uhler —Deviation Produced by Prisms. 411 



Table I. 



£ 



Families, 

 D 



Intercept, 

 A-axis. 



Intercept, 

 rj /-axis. 



Boundary intersections 



Extreme 

 values. 





W 



fix 





o 

 o 



o 



IN 



14° 



18 



23 



27 

 31 



31' 



50 



9 



29 



48 



7" 

 27 



48 



9 

 29 



22° 5' 2" 

 27 15 1 



29 46 12 



31 2 58 

 31 38 34 



34° 8' 1" 



39 50 1 



beyond 



boundary 

 it 



2° 



11 



20 



47' 45" 



31 

 49 53 



40° 



37 

 29 



9' 6" 



1 9 

 46 10 



e =10° 11' 46" 

 j D,=m 7 50 

 / 1 =31 48 37 

 j Z) 2 =22 23 22 



{ V=40 48 44 



X 

 lT 



£~ 



BQ 



o 



CO 



29 

 34 

 39 

 44 





 

 

 





 

 

 



13 28 53 



17 9 20 



18 56 27 



19 45 48 



24 45 40 



31 27 56 

 34 41 50 



36 10 47 







e = 24 7 35 

 (D 1 =49 6 5 

 } 7, =19 59 38 

 j D 2 =49 6 5 

 "j ^' = 36 35 46 



OS 



CO 



o 



o 



43 

 48 

 53 



58 



63 



6 

 16 

 25 



35 



44 



49 



18 

 46 



15 



44 



8 14 52 



10 19 49 



11 12 7 

 beyond 



boundary 



18 56 15 

 24 29 5 

 27 29 35 



29 9 38 



29 58 50 



F; 8 

 E; 



3 21 



39 7 



17 

 29 



51 57 

 32 28 



e =37 57 20 

 jD 1 = 58 24 43 

 \X =11 24 48 

 (Z> 2 =68 54 13 

 "j ?i' = 30 12 55 



b 

 b 



61 

 66 



71 



76 



80 



42 

 31 



20 



9 



58 



9 



8 



6 



4 

 3 



3 28 55 



4 11 20 



beyond 



boundary 

 tt 



12 12 16 



15 57 9 



18 3 17 



19 15 10 

 19 51 23 



J; 3 



H; 1 

 G; 



17 58 



30 



11 27 



10 



17 



10 



3 41 



43 39 

 37 25 



£„ =56 53 11 

 {D,=70 11 49 

 ) 1 = 4 18 37 

 jZ> 2 =85 47 1 

 I ?/=20 1 56 



stant deviation to intersect the boundary in two discrete points. 

 Thus for D = 22° 13' 2" the close intersections with the 

 boundary locus are given by X =0° 57' 19% 77/ = 40° 36' 25% 

 and X = 0° V 34% 77/ = 4=0° 48' 25". In order to show the 

 distribution of deviation along the boundary locus of figure 3 

 the following numerical data have been calculated. [This dis- 

 tribution is shown in another way in figure 6.] At M the 

 deviation has the minimum value 45° 22' 46% with the coor- 

 dinates X = 3° 40' 13% 77/ = 34° 20' 22". At the points AA, 

 D = 46% X = 8° 12' 47" with 77/ = 30° 34' 48" and X = 

 1° 9' 18" with 7;/ = 35° 56' 52". At BB, D = 47% X = 

 12° 21' 20" with 77/ = 25° 43' 29", and \ = 0° 21' 36" with 

 77/ = 36° 23' 59". ' At CC, D = 48% X = 16° 4' 5" with 77/ = 

 19° 11' 55" and X = 0° 4' 39" with 77/ = 36° 33' 16". For D 

 = 48° 40' the point D is given by X = 18° 27' 26" with 

 77/ = 12° 20' 3". The upper intersection, which could not be 

 plotted, has the coordinates X = 0° 0' 38" and 77/ = 

 36° 35' 26" 



Figure 6 pertains to the 7^/) surface in that it shows the 

 dependence of the deviation at grazing incidence upon the 



