-------------------+--------------------+----------+---------- Angle of Incidence |Angle of Refraction |Diameter |Thickness on | into | of the | of the the Air. | the Air. | Ring. | Air. -------------------+--------------------+----------+---------- Deg. Min. | | | | | | 00 00 | 00 00 | 10 | 10 | | | 06 26 | 10 00 | 10-1/13 | 10-2/13 | | | 12 45 | 20 00 | 10-1/3 | 10-2/3 | | | 18 49 | 30 00 | 10-3/4 | 11-1/2 | | | 24 30 | 40 00 | 11-2/5 | 13 | | | 29 37 | 50 00 | 12-1/2 | 15-1/2 | | | 33 58 | 60 00 | 14 | 20 | | | 35 47 | 65 00 | 15-1/4 | 23-1/4 | | | 37 19 | 70 00 | 16-4/5 | 28-1/4 | | | 38 33 | 75 00 | 19-1/4 | 37 | | | 39 27 | 80 00 | 22-6/7 | 52-1/4 | | | 40 00 | 85 00 | 29 | 84-1/12 | | | 40 11 | 90 00 | 35 | 122-1/2 -------------------+--------------------+----------+---------- In the two first Columns are express'd the Obliquities of the incident and emergent Rays to the Plate of the Air, that is, their Angles of Incidence and Refraction. In the third Column the Diameter of any colour'd Ring at those Obliquities is expressed in Parts, of which ten constitute that Diameter when the Rays are perpendicular. And in the fourth Column the Thickness of the Air at the Circumference of that Ring is expressed in Parts, of which also ten constitute its Thickness when the Rays are perpendicular.