PR. BREWSTER ON THE PHENOMENA AND LAWS 
Angle of Incidence of 
the two Reflexions. 
Colours with ordinary Light. 
O 
63 . . 
Very pale yellow, growing whiter at less incidences 
64 . . 
Pale yellow. 
65 
Pale saffron yellow. 
66 . . 
Saffron yellow. 
67 . . 
Paler orange yellow. 
68 . . 
Orange yellow. 
69 . . 
Reddish orange. 
70 . . 
Tile red. 
70^ . . 
Vermilion red. 
71 • • 
Scarlet. 
72 . . 
Bright pink. 
73 . . 
Dark pink. 
74 . . 
Deep China blue. 
75 . . 
Indigo. 
75-4 
/o 2 . . 
Pure bright blue. 
76 . . 
Paler blue. 
77 • • 
Whitish blue. 
78 . . 
Blueish white, growing white at greater angles. 
It is obvious from what has been already stated, that with homogeneous 
yellow light the pencil will not vanish in passing from 73°, where it is eva- 
nescent, to 90°, and 0° where it is also evanescent ; but the intensity of the 
extraordinary pencil of the analysing rhomb will increase from 0° to half the 
reflected light, from 73° to 82^°, and from 73° to 57° 16', and will decrease from 
the same points to 90° and 0°. The same is true of the red and blue rays, the 
former having its maximum intensity at an angle greater than 82^° and greater 
than f»7° 16', and the latter at an angle less than 82^° and less than 57° 16'. 
In order to ascertain the phenomena in homogeneous light, let us suppose 
i hat polarized yellow light suffers four reflexions from silver, and let us consider 
what should take place in the loop 2, 3 of the quadrant IV, IV. (See Fig. p.31 8.) 
At the node 2, or 73°, the inclination of the restored pencil is +31° 52', and at 
tin node 3, or 82° 30', it is —37° 22', and the point of maximum between 2 and 
3 i> at 78" 8'. If at 7 3° we place the principal section of the analysing prism 
