Colors in the Water

Red is outside in the inner rainbow and inside in the outer one.

This is based on the same cause for which it appears towards F, rather than towards H, through the MNP prism.

If the eyes is on white linen FGH looking at this crystal, he will see:

• red towards its thicker part MP
• blue towards N

This is because the red-tinted ray that goes to F comes from C, the part of the sun most advanced towards MP.

This means that the thicker center of the raindrops are:

• outside with respect to the colored points that form the inner rainbow.
  • This causes red to appear there outside.
• inside with respect to the colored points that form the outer rainbow.
  • This causes the red to appear there inside.

The only difficulty are the irregularities that occur there.

Examples are when:

• the arc is not exactly round
• the arc’s center is not in the straight line that passes through the eye and the sun.

These can happen if the winds change the shape of the raindrops.

This makes a notable difference in the angle under which the colors should appear.

We have also seen sometimes, so I am told, a rainbow so overturned that its horns were turned upwards, as is represented here in FF.

This is caused by the reflection of the sun’s rays falling on the water of the sea or lake.

As if coming from the part of the sky SS, they fall on the water DAE.

From there, they reflect towards the rain CF. The eye B will see the arc FF, whose center is at point C, so that CB being extended to A, and AS passing through the center of the sun, the angles SAD and BAE are equal, and the angle CBF is about 42 degrees.

This requires there to be:

• no wind at all to disturb the water’s surface towards E
• some cloud, like G, which prevents the sunlight going in a straight line towards the rain

In this way, it does not erase the one that this water E sends there.

• From which it comes that it happens only rarely.

The eye can be in a position relative to the Sun and the rain that the lower part that completes the circle of the rainbow will be seen, without seeing the upper part.

Thus it will be taken for an overturned arc.

It will not be seen towards the sky, but towards the water, or towards the earth.

A third much weaker rainbow has sometimes been seen above the 2 ordinary ones.

• It was as far from the second as the second was from the first.

This needs very round and very transparent hailstones mixed with the rain.

This would make the refraction greater than in water.

This would make the outer rainbow much larger there, and thus appear above the other.

The inner one which by the same reason should have been smaller than the inner one of the rain, it may be that it will not have been noticed, because of the great luster of this one: or that their ends having joined, they will not have been counted both for one.

But for one whose colors will have been arranged differently than usual.

There is an fountain invention to make signs appear in the sky.

The water comes out of the small holes ABC jumps high and spreads in the air in all directions towards R.

The sun is at Z so that ZEM is a straight line. The angle MER is around 42 degrees.

The eye E will see the iris towards R, quite similar to the one that appears in the sky.

There are oils, spirits of wine, and other liquids, in which refraction is significantly greater or smaller than in ordinary water yet just as transparent.

Several fountains could be arranged so that these liquids, one would see by their means a whole large part of the sky full of the colors of the iris:

namely by making the liquids, whose refraction would be the greatest, be the closest to the spectators; and that they do not rise so high that they prevent the view of those that would be behind.

Then because by closing part of the holes ABC one can make disappear such part of the iris RR as one wants, without removing the others.

In the same way, opening and closing the holes of these various fountains at the right time, we can make what appears colored have the figure of a cross, or a column, or some other thing.

But it would take skill and expense to:

• proportion these fountains
• make the liquids jump so high that these shapes could be seen from afar by a whole people, without the artifice being discovered.