Interference Bands formed by Rays at Small Angles. 195 



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Note on Interference Bands Formed by Eays Making Small 

 Angles with the Eeflegting Surface. 

 When light falls very obliquely on flat superposed plates separated by a 

 small interval, no interference bands can be distinguished, owing to the 

 nearly complete reflection which takes place at the first surface and over- 

 powers the weak rays penetrating to, and reflected from, the surfaces where 

 the interference occurs. If, however, a prism is substituted for the upper 

 plate, the interference bands, due to rays whose path in the air space 



