22 Rbeinberg: Common Basis ofthe Theories ofMicroscopic Vision. XIX, 1. 



out central Image into 3 Images approximately equal in widtli and 

 mueb more abrupt in their transition from liglit to darkness. (The 

 diagram of course only shows the effect on one side.) A further 

 outside band on each side, 3 r, of only half the width of the others 

 is formed, but is of relatively so little luminosity as to be invisible, 

 and may be neglected. The effect just described is easily denion- 

 strated experimentally, see figure 21, which should be compaved with 

 ligure 1 7 . 



Now see what takes place if we double or treble the width ot 

 the Space between the two slots, as shown diagrammatically in 



24. 



figures 24 and 25 respectively , and actually in figure 22 and 23 

 respectively. In the first case just twice, and in the second just 

 three times as many directions arise in which the interference etfects 

 of the two Slots produce total destruction of the light. Consequently 

 we get the space occupied by the broadened out central Image of 

 one Slot divided into 5 bands or 7 bands respectively, moreover the 

 transitions from light to darkness increase in abruptness. 



It has therefore become apparent that a doubling or trebliug 

 of the distance between the slots has produced a doubling or trebling 

 of the number of bands on each side of the central one, and any 

 further increase of the distance separating the two, would result in 

 a further proportional addition to the number of bands. We can 



