iameter of this Ring, measured from the middle of its Light on one
side to the middle of its Light on the other side, was always equal to
the distance between the middle of the incident beam of Light, and the
middle of the reflected beam measured at the Chart on which the Rings
appeared: And the Rays which form'd this Ring were reflected by the
Speculum in Angles equal to their Angles of Incidence, and by
consequence to their Angles of Refraction at their entrance into the
Glass, but yet their Angles of Reflexion were not in the same Planes
with their Angles of Incidence.

_Obs._ 11. The Colours of the new Rings were in a contrary order to
those of the former, and arose after this manner. The white round Spot
of Light in the middle of the Rings continued white to the center till
the distance of the incident and reflected beams at the Chart was about
7/8 parts of an Inch, and then it began to grow dark in the middle. And
when that distance was about 1-3/16 of an Inch, the white Spot was
become a Ring encompassing a dark round Spot which in the middle
inclined to violet and indigo. And the luminous Rings encompassing it
were grown equal to those dark ones which in the four first Observations
encompassed them, that is to say, the white Spot was grown a white Ring
equal to the first of those dark Rings, and the first of those luminous
Rings was now grown equal to the second of those dark ones, and the
second of those luminous ones to the third of those dark ones, and so
on. For the Diameters of the luminous Rings were now 1-3/16, 2-1/16,
2-2/3, 3-3/20, &c. Inches.

When the distance between the incident and reflected beams of Light
became a little bigger, there emerged out of the middle of the dark Spot
after the indigo a blue, and then out of that blue a pale green, and
soon after a yellow and red. And when the Colour at the center was
brightest, being between yellow and red, the bright Rings were grown
equal to those Rings which in the four first Observations next
encompassed them; that is to say, the white Spot in the middle of those
Rings was now become a white Ring equal to the first of those bright
Rings, and the first of those bright ones was now become equal to the
second of those, and so on. For the Diameters of the white Ring, and of
the other luminous Rings encompassing it, were now 1-11/16, 2-3/8,
2-11/12, 3-3/8, &c. or thereabouts.

When the distance of the two beams of Light at the Chart was a little
more i