071 the Podura Scale. By E. M. Nelson. 403 



experiments were performed with an ordinary 3-in. objective, with 

 its aperture reduced to less than lialf, and the various appearances 

 detailed above were observed. These experiments prove that 

 the depolarisation of light by a Podura scale is not caused by 

 spectra given off by its periodic structure. There appears to be no 

 evidence that rows of holes are capable of depolarising light, and 

 consequently the argument in my paper is sound. 



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