XIX, 1. Kbeinberg: Common Basis of the Theories of Microscopic Vision. 2 7 



— ( nun 



If the Position of the 1 st. 2 nd. 3 rd. 4 th. etc. 



maximum of the violet rays are ... 1 — 3 — 5 



respectively from the central image, then 

 the Position of corresponding maxima 

 for the red rays are about 1*/., — 4\, — 7\., — 10'/., „ 



and consequently the length of the spec- 



tra are V, - l^/, - 2 V. - 3V, „ 



One or two rules about the Images formed by a uumber of 

 regularly spaced slots are wortb noting: 



1) The Position of the maxima depends solely ou the number 

 of the slots in a g-iven width, it is independeut of the relative width 

 of the slots to the interspaces. Thus all the rows in figure 30 give 

 their maxima at the same points. This follows because the position 

 of the maxima depends lipon the distance of auy point in one slot 



30. 



31. 



to a corresponding point in the uext (see figs. 20, 24, 25) which 

 is the same tliing as the sum of the width of one slot plus one 

 iuterspace. In this respect all the rows in figure 30 are similar. 



2) With an equal number of slots the brightness of the 

 maxima is directly dependent on the relative width of the slots to 

 the interspaces. For reference to figures 20, 24, 25, 26, and 29 will 

 show that the maxima must be located on a ciirve formed by mul- 

 tiplying the intensity curve of a Single slot by the number of slots in 

 question, and the intensity curve of the Single slot over any given 

 distance varies greatly according to its width. Figure 3 1 represents the 

 intensity - curves of three series of slots A, B and C, slots B being 

 one half, and slots C one third the width of Ä. P' Q S U s,how 

 the Position of the chief image and maxima, and it may be seen at 

 a glance how the narrower slots Ä tend to equalize the brightness 

 of the first few maxima. 



