|
Colours
by Jonathan Edwards
COLOURS we have already
supposed that the Different Refrangibility of Rays Arises from their
Different bulk, we have also supposed that they Are very Elastic bodies,
from these suppositions the Colours of natural bodies may be accounted
for that is why some Particles of matter Reflect a sort or sorts of Rays
and no Other the Different Density of Particles whence Arises a
Different attraction and together with their Different firmness will
account for all some bodies have so little of firmness and so Easily
Give way that they Are able to Resist the stroak of no Rays But the
Least and Weakest, and most Reflexible Rays, all the other Rays that Are
bigger and therefore their force not so Easily Resisted overcome the
Resistance of the Particles that stand in their way such bodies
therefore appear blue as the atmosphere or skies, smoke &c. — again tis
known that the most Refrangible Rays are most easily attracted that is
are most easily stay’d or diverted by attraction, for as has been
already shown Refraction & Reflection from Concave surfaces is by
attraction because therefore that the most Refrangible Rays are most
Diverted by Refraction and Easiest Reflected inward from the surface,
and most Diverted by Passing by the edges of bodies it follows that
attraction has most influence on the most Refrangible Rays.
’Tis also evident that the Particles of bodies that are the most Dense
have the strongest attraction. the Particles of any body therefore may
be so dense and attract so strongly as to hold fast all the Lesser and
more Refrangible Rays so that they shall none of them be Reflected but
Only the Greater Rays, on Whom the attraction of these Particles Can
have Less influence, hereby the body will become Red and as for the
intermediate Colours the Particles of a body may be so Dense as to hold
all the most Refrangible Rays and may yet not be firm Enough to Resist
the stroak of the Least Refrangible hereby the body may become Yellow or
Green or of any other intermediate Colour.
Or a body may be Colourd by the Reflection of a mixture of Rays the body
Particles may be able to Reflect three or four sorts of Rays and have
too strong an attraction to Reflect those Rays that are Less and too
weak a Resistance to Reflect the Bigger Rays, or the Colour of A body
may be Compounded of Reflected Rays of very Distant Degrees of
Refrangibility and not Reflect any of the intermediate Colours by reason
of its being Compounded of very heterogeneous Particles [which] have a
very Different Degree of Density and firmness, or the Particles of a
body may be firm Enough to Reflect all sorts of Rays yet have so little
attraction to hold them that the body will be White, or a body may be
Compounded of Particles having so little Resistance as to Reflect no
Rays, of so Great Density as to hold all or so full of Pores as to Drink
in all, then the body is black
Or the Particles of bodies may have Pores and hollows that may be big
enough to Let in the Least Rays not the Rest so that the Pores of
Particles may have much to Do in the Causing of Colours
The blue of mountains at a Distance is not made by any Rays Reflected
from the mountains but from the Air and vapours that is between us and
them. the mountain occasions the blueness by intercepting all Rays that
would Come from beyond to Disturb the Colour by their mixture it may
therefore seem a Difficulty Why the atmosphere all Round by the horizon
Dont appear very blue seeing tis Evident that the atmosphere Reflects
Chiefly the blue Rays as Appears In the higher Parts of the atmosphere
by the blueness of the skie and near the Earth by the blueness of
mountains, and the Redness or Yellowness of the Rising and setting sun,
it would therefore seem that the atmosphere should appear most blue
where no Rays are Intercepted by mountains because the atmosphere beyond
the mountain Reflects blue Rays as well as on this Side, therefore it
seems that there would be more blue Rays Come to Our Eyes where none
were intercepted by mountains. And Consequently that the most lively
blue would be there. and so it would be, if blue Rays Came to our Eyes
in the same Proportion as they are Reflected but most of those blue Rays
that Are Reflected by those Parts of the Atmosphere that Are at a great
Distance are intercepted by the intermediate Air before they Come to Our
eyes (for the Air by supposition intercepts them Easiest) and only those
few Yellow Rays and Less Reflexible Rays that are Reflected by the Air
Come to our eyes whence it Comes to Pass that the Atmosphere near the
horizon Dont appear blue but of a Whitish Yellow. And sometimes when it
is filled with more Dense exhalations that Can Reflect Less Reflexible
Rays still, it appears a little Reddish.
|
