PLATE VI. 
Fig. 1.—Haidinger’s tufts, as seen through a Nicol’s prism on a clear 
sky ; plane of polarisation vertical. 
Fig. 2.—Haidinger’s tufts, as seen projected on a brightly-lighted 
sheet of paper placed 160 cm. (about 5 feet) from the eye. 
The plane of polarisation is here horizontal, and the 
diffuse transverse violet colouration is omitted. 
