Of the fourth Order, {Yellowish green | 36 | 27 | 23-2/9 |
{Red | 40-1/3 | 30-1/4 | 26 |
|---------+----------+----------|
{Greenish blue | 46 | 34-1/2 | 29-2/3 |
Of the fifth Order, {Red | 52-1/2 | 39-3/8 | 34 |
|---------+----------+----------|
{Greenish blue | 58-3/4 | 44 | 38 |
Of the sixth Order, {Red | 65 | 48-3/4 | 42 |
|---------+----------+----------|
Of the seventh Order, {Greenish blue | 71 | 53-1/4 | 45-4/5 |
{Ruddy White | 77 | 57-3/4 | 49-2/3 |
|---------+----------+----------|
There are also other Uses of this Table: For by its assistance the
thickness of the Bubble in the 19th Observation was determin'd by the
Colours which it exhibited. And so the bigness of the parts of natural
Bodies may be conjectured by their Colours, as shall be hereafter shewn.
Also, if two or more very thin Plates be laid one upon another, so as to
compose one Plate equalling them all in thickness, the resulting Colour
may be hereby determin'd. For instance, Mr. _Hook_ observed, as is
mentioned in his _Micrographia_, that a faint yellow Plate of _Muscovy_
Glass laid upon a blue one, constituted a very deep purple. The yellow
of the first Order is a faint one, and the thickness of the Plate
exhibiting it, according to the Table is 4-3/5, to which add 9, the
thickness exhibiting blue of the second Order, and the Sum will be
13-3/5, which is the thickness exhibiting the purple of the third Order.
To explain, in the next place, the circumstances of the 2d and 3d
Observations; that is, how the Rings of the Colours may (by turning the
Prisms about their common Axis the contrary way to that expressed in
those Observations) be converted into white and black Rings, and
afterwards into Rings of Colours again, the Colours of each Ring lying
now in an inverted order; it must be remember'd, that those Rings of
Colours are dilated by the obliquation of the Rays to the Air which
intercedes the Glasses, and that according to the Table in the 7th
Observation, their Dilatation or Increase of their Diameter is most
manifest and speedy when they are obliquest. Now the Rays of yellow
being more refracted by the first Superficies of the said Air than those
of red, are thereby made more oblique to the second Superficies, at
which they are reflected to produce the colour'd Rings, and consequently
131