342
Of Light and Colours.'
transmitted wholly or in Part; and thatwhich is reflected will be all of one Sort of
Rays ,
was removed farther from the Axis. And by measur-ing the Diameters of the fame Circle at several Obli-quities of the Eye, and by some other Methods, SirIsaac found its Diameter, and consequently the Thick-ness of the Air at its Periphery in all those Obliquities,to be very nearly in the Proportions expressed ih thefollowing Table ; where the first Column expresses theAngles of Incidence which the Rays of Light make withthe Perpendicular in the Glass ; the second Column ex-presses the Angle of Refraction into the Plate of Air ;the third Column strews the Diameter'of any colouredRing at those Obliquities expressed in Parts, of whichten constitute the Diameter when the Rays are perpen-dicular ; and the fourth Column strews the Thicknessof the Air at the Periphery of that Ring expressed inParts, of which the Diameter consists of ten also whenthe Rays are perpendicular.
Angle of In-cidence on thePlate of Air.
Angle of Re-
fraction intothePl. of Air.
Diameterof theRing.
Thicknessof theAir.
Deg.
Min.
Deg.
Min.
•
oo
OO
OO
00
10
IO
o 6
26
10
00
.IOtV
IO T \
12
45
20
00
IOi
?o|
13
49
30
' 00
I°i
I'4
24
30
40
00
1 if
13
29
37
5 °
00
I 2i
Mi
33
58
60
00
14
20
35
47
65
po
- 5 i
23 s
37
1 9
7 0
00
1 64
285
38
33
75
00
1 9 \
37
39
27
80
00
22 f
5 2 t
40
OO
85
00
23
84A-
40
11
90
00
35
122b
18. By looking through the two contiguous Object-Glasses or Prisms it was observed that the Rings °fIpolours appeared as well by transmitted as by reflected
Light,