DOI Page / Citation link:
https://doi.org/10.11588/diglit.19574#0125
tion or reflection, but immutable properties, and fuch as belong
to the nature of the rays.
5. An afTemblage of all the kinds of coloured rays, collected
either by feveral prifms, by a convex lens, or a concave mirror,
or in any other manner, from what we call whitenefs; yet each
of thefe, after decuffation becoming feparated again, exhibits its
proper Colour; for, as the ray was white before its parts were fe-
parated by refraction, fo, the parts being re-mixed, it becomes
white again j and coloured rays, when they meet together, da
not deftroy one another, but are only interfperfed : Hence a red,
green, yellow, blue, and violet colour, being mixed in a certain
proportion, appear whitifh, i. e. are of fuch a Colour as arifes
from white and black mixed together, and, if there were not fome
rays abforbed and loft, would be plainly white. In like man-
ner, if a paper, cut into a circle, be ftained with each of thofe
Colours feparately, and in a certain proportion ; then fwiftly
turned round its center, fo that the fpecies of Colours be mixed
together in the eye; by the brifknefs of the motion, the feveral
Colours will difappear; and the whole paper appear of one con-
tinued Colour, which will be a mean between white and black.
6. If the rays of the fun fall very obliquely on the inner fur-
face of a prifm, thofe that are reflected will be of a violet Colour;
thofe that are tranfmitted red. For the rays were coloured be-
fore any feparations; and, by how much the more they are re-
frangible, by fo much they are the more eafily reflected, and by
that means are feparated.
7. If two hollow prifms, the one being filled with a blue fluid,
and the other with a red one, be joined together, they will be
opaque, though each, being apart, will be tranfparent: For, the
one tranfmitting none but blue rays, and the other none but red
ones, the two together will tranfmit none at all.
8. All natural bodies, efpecially white ones, viewed through
a prifm held to the eye, appear fimbriated, or bordered on one
fide with red and yellow, and on the other with blue and violet.
For thofe fimbriae are the extremes of intire images, which the
rays of any kind, as they are more or lefs refracted, would ex-
hibit nearer or at a greater diftance from the real place of the
object.
9. If two prifms be fo placed, as that the red of the one, and
the purple of the other meet together, in a paper fit for the pur-
pofe, incompaffed with darknefs, the image will appear pale;
and, if viewed through a third prifm, held to the eye at a proper
diftance, it will appear double, the one red, and the other purple.
In like manner if two powders, the one perfectly red, and the other
blue, red and purple be mixed, any little body, covered pretty
deeply with this mixture, and viewed through a prifm held to the
eve,
to the nature of the rays.
5. An afTemblage of all the kinds of coloured rays, collected
either by feveral prifms, by a convex lens, or a concave mirror,
or in any other manner, from what we call whitenefs; yet each
of thefe, after decuffation becoming feparated again, exhibits its
proper Colour; for, as the ray was white before its parts were fe-
parated by refraction, fo, the parts being re-mixed, it becomes
white again j and coloured rays, when they meet together, da
not deftroy one another, but are only interfperfed : Hence a red,
green, yellow, blue, and violet colour, being mixed in a certain
proportion, appear whitifh, i. e. are of fuch a Colour as arifes
from white and black mixed together, and, if there were not fome
rays abforbed and loft, would be plainly white. In like man-
ner, if a paper, cut into a circle, be ftained with each of thofe
Colours feparately, and in a certain proportion ; then fwiftly
turned round its center, fo that the fpecies of Colours be mixed
together in the eye; by the brifknefs of the motion, the feveral
Colours will difappear; and the whole paper appear of one con-
tinued Colour, which will be a mean between white and black.
6. If the rays of the fun fall very obliquely on the inner fur-
face of a prifm, thofe that are reflected will be of a violet Colour;
thofe that are tranfmitted red. For the rays were coloured be-
fore any feparations; and, by how much the more they are re-
frangible, by fo much they are the more eafily reflected, and by
that means are feparated.
7. If two hollow prifms, the one being filled with a blue fluid,
and the other with a red one, be joined together, they will be
opaque, though each, being apart, will be tranfparent: For, the
one tranfmitting none but blue rays, and the other none but red
ones, the two together will tranfmit none at all.
8. All natural bodies, efpecially white ones, viewed through
a prifm held to the eye, appear fimbriated, or bordered on one
fide with red and yellow, and on the other with blue and violet.
For thofe fimbriae are the extremes of intire images, which the
rays of any kind, as they are more or lefs refracted, would ex-
hibit nearer or at a greater diftance from the real place of the
object.
9. If two prifms be fo placed, as that the red of the one, and
the purple of the other meet together, in a paper fit for the pur-
pofe, incompaffed with darknefs, the image will appear pale;
and, if viewed through a third prifm, held to the eye at a proper
diftance, it will appear double, the one red, and the other purple.
In like manner if two powders, the one perfectly red, and the other
blue, red and purple be mixed, any little body, covered pretty
deeply with this mixture, and viewed through a prifm held to the
eve,