in the polarized Tints of cert cun Crystals with one Axis. 333 
Table V I.-— Continued. 
Incidence. 
Ordinary Pencil. 
Extraordinary Pencil. 
25° 3' 
26* V 
Ruddy but pale yellow. 
Pink, light and approaching to 
brick-red. 
Fine pink. 
Pink. 
Pale purple. 
Dull blue. 
Bright greenish-blue. 
Blue green. 
White. 
Blue. 
Bright greenish -blue. 
Splendid green. 
Light green. 
Greenish-white. 
Ruddy white. 
Tolerable pink-red. 
Fine rose-red. 
Dull pale purple. 
29° 33' 
31® 35' 
35° 27' 
Ruddy white. 
Good pink red. 
Dull pale purple. 
Light blue green. 
White. 
Blue, rather pale. 
Green blue. 
White. 
Pink-red. 
Very pale purple. 
39° 32' 
Light pink. 
White. 
Extremely pale blue. 
White. 
Very light blue. 
White. 
Almost imperceptible pink. 
White. 
L__™ 
The colours here cease to be perceptible after the fourth order, 
and the degradation of the tints is evidently much more rapid 
than in Newton’s Scale. Thus the blue of the first order, which 
in that scale is scarce perceptible, is here sufficiently strong to 
influence its complementary tint, depressing it to a pale yellow. 
The green and its complementary pink of the second order in 
this T'able are fully equal in brilliancy to those of the third in 
Newton’s Scale, while those of the third are scarcely equal to 
Newton’s fifth. Accordingly, by a series of measures taken 
with considerable care in homogeneous light, I found the values 
of l for the several simple colours as follows : 
Table VII 
riods in 
. — * Scale of the Minimum Lengths of the Pe~ 
Hyposulphate of' Lime , and their reciprocals. 
Minimum length of 
Polarizing power or 
Number of 
Name of Colour. 
its period, or va- 
lue of L 
„ 1000000 
value of p 
Observa- 
tions. 
Extreme red. 
3241 
308.54 
38 very exact. 
Mean orange. 
2454 
407.45 
26 
yellow. 
2129 
469.65 ^ 
28 
green. 
1861 
537.32 
20 
blue. 
1658 
603.21 
20 
indigo. 
1480 
675.83 
20 
Extreme violet. 
1129 
885.77 
29 
