OF ARTS AND SCIENCES. 



23 



TABLE XIII., — continued. 

 Observed Polarization of 1, 2, 8, and 20 Surfaces of Glass. 



in front of it quartz wedges giving lines, which were bright or dark 

 centred, according as the transmitted ray was polarized vertically or 

 horizontally. Ou looking through the telescope, the field was seen to 

 be traversed with lines, which disappeared only when the Nicol in the 

 collimator was inclined 45° with the vertical. At any other angle, a, 



