from the Boundaries of Diffracting Apertures. 125 



Another case, in which the disparity between f 2 and £ 2 

 was much smaller, was chosen for experimental verification 

 of the position of the diffraction maxima and minima given 

 by theory. Jt is found that the illumination falls off to 



Table IV. 



f 1 =-654mm., f s = -963 mm., /=13'4 

 A,= -00045 mm., 

 width of the aperture =0*955 mm. 



cm., 









Calculated values 



Observed value 



<p/9. 



v/i- 



I 



(X const, factor). 



of 0/6/ 

 for maximum 

 or minimum. 



of <p/Q 

 for maximum 

 or minimum. 



•760 



-•0002 







•760 min. 



•756 



•780 



+ •1468 



204 







•800 



+ -2123 



449 



•800 max. 



•802 



•820 



+ ■1463 



201 







•840 



- -0018 







•840 min. 



•843 



•860 



-•1601 



256 







•880 



-•3084 



957 



•888 max. 



■882 



•900 



-•2369 



559 







•920 



-•0065 







•923 min. 



•927 



•930 



+ •1337 



179 







•940 



+•2386 



567 







•950 



+ •3416 



1167 







•960 



+ 6707 



4498 



•960 max. 



•961 



•970 



+ •3431 



1177 







•980 



+ •2398 



575 







•990 



+-•1350 



182 







•995 



+ •0620 



38 







1-000 



-0145 



2 



1-000 min. 



1-000- 



1-005 



-•0918 



84 







1-010 



-•1528 



233 







1-020 



-•2587 



669 







1-030 



-•3701 



1370 







1-040 



-•6898 



4758 



1-04 max. 



1-038 



1-050 



-•3648 



1331 







1-060 



-•2517 



634 







1-070 



-•1513 



229 







1-080 



-•0059 







T080 min. 



1-076 



1-100 



+ •2431 



589 







1-120 



+•3196 



1021 



1-114 max. 



1-115 



1-140 



+•1713 



293 







1-160 



-•0024 







1-16 min. 



1-157 



1-180 



-•1642 



270 







1-200 



-•2128 



453 



1*198 max. 



1-205 



1-220 



-•1478 



218 







1-240 



-•0002 







1-24 min. 



1-238 



