Baebett — A New Form of Polarimeter. 



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latter contains a lens in a draw-tube, so that a parallel beam falls on the 

 opaque reflecting surface ; and a sharp image of the slit is obtained by the 

 lens in the telescope, which also contains a small Nicol's prism. Upon 

 turning the rack-work handle, the source of light and collimator move 



together, and through the same angle as the telescope. The observer now 

 turns the polarizing plane of the Nicol at right angles to the plane of the 

 reflected polarized ray, and watches the gradual extinction of the light as the 

 polarizing angle is approached. At the angle of maximum polarization the 



