Phil. Mag. Ser. 6, Vol. 22, PI X 













1-Z.fa 



















i 











I 



JJ 



L 



r 





g 











A 



A=a/ a 



if- 









n 



A 







K 



J 



L 



n 



/ r 













12, 











A-i/ 



! 















<t 











A 













1/ 



V 



/s 



1 







71-Jt^t. 



J 1 

















j 









. 





-11 



1 



u 



^ 



.-/ 























h'lbw 







! 



1 

















A 







L/ 



J- 



1 / 



/ \ 



X 







Fig. 







\r-/.S/v 







i 



























\ / 



VV 



ti. 



/ 











A 



A-,3^*, 











rl 



A 







A 



J 



L 



7 l 



/ 



\ 





















X'^ 



















A 



J 



















' l 







A 



A»-g<7«, 



M 











Uuv 





1 





^ 



»** .»■ 

















n 





A--z^ 



























A 









j 



L 



j \ 



7 





<? 





,1 



1 





k-^ 



^ 











A 













-J 



i/ 













A 



i 



1 



<^_ 



\ 



i 



J 



U 





J 



ltitla" 



i ■ 















Fig 



11. 





















A=^ 











1 























y-^J 











1 







k 



.! 







1 





A 



/! '//£,. 



1 :■■ 



> 













X-te* 





































J 





^-N 



BRACKET GRATING No. IO. 



GRATING SPACE: 00067 cm. 



ANGLE BETWEEN COLLIMATORS : 20=30°. 



Form of Groove (Approximate;. 





