in the Optical Phenomena of Mother of Pearl. 401 
experiment; and the fourth, formed by adding the 2d and 3d 
columns, contains the complement of theangle of extraordinary 
reflection. 
Angle of 
incidence. 
Coniplcmexit of the 
angle of incidence. 
Observed 
angle of 
abcn’alion. 
Complement of 
the angle of 
extraordinary 
reflection. 
Calculated 
angle of 
aberration. 
86° — 40' 
3°— 20' 
9®- 14' 
I2°_ 34' 
9®— 26' 
85 
5 
8-46 
13 — 46 
8 _ 38 
82 — 30 
7 — 30 
7-58 
15 — 28 
7—41 
80 
10 
7 — 12 
17 — 12 
6-55 
75 
^5 
5 -50 
20 — 50 
5 - 52 
70 
20 
5 - 0 
25 — 0 
4-56 
65 
25 
4-9 
29-9 
4-17 
60 
30 
3 - 45 
33 - 45 
3 — 44 
55 
35 
3 — 25 
38 - 25 
3 — 20 
50 
40 
3 - 9 
43-9 
3 — I 
45 
45 
2 - S 3 
47 — 53 
2 — 48 
40 
50 
2-35 
52 — 35 
2-37 
35 
55 
2—30 
57 - 30 
2 — 28 
30 
60 
2-25 
62 — 25 
2 — 21 
25 
65 
2—17 
67 — 17 
2 — 15 
20 
70 
2 _ 13 
72 — 13 
2-9 
12 
78 
2-7 
80 — 7 
2—7 
iRrC rzSrC 
Arr SrB =: RrA 
X — srS 
A 4- ;r — srB 
X 
If we now compare the angles of aberration in the third 
column with the angles of extraordinary reflection in the 
fourth column, and make 
A = RrA = SrB the complement of the angle of incidence 
or ordinary reflection. 
X = srS the angle of aberration. 
A + X 5rB the complement of the angle of extraordinary 
reflection, it will be found that 
sin. X : sin. sin. A' + A -j- a; 
That is, the sines of the angles of aberration are to one another ' 
inversely, as the sines of the complements of the angles of 
extraordinary reflection. 
