The shower passed over as quickly as it had arisen, so the Band decided to start for Camp. The ground had been very dry and the rain soaked in rapidly, leaving the surface comparatively dry.
"I wonder if Nita was frightened at the shower?" said Zan, as they followed her down the trail.
"I'd rather have had company on that Bluff—but it is her own fault," said Hilda.
"Oh, girls, see the rainbow—isn't it a beauty!" exclaimed Miss Miller at this point.
The girls all stopped and admired the wonderful hues in the bow and Jane asked, "What makes a rainbow, Miss Miller?"
"Look, girls! There's another one—right near the other!" cried Zan, pointing.
"There usually are two, according to the brilliancy with which the sun reflects upon the opposite clouds when they are resolved into rain. Look at those two carefully! See the lower one is brighter than the second one. Also look quickly before it fades and see that the colours are reversed in their order; and in one, red is the highest colour, while violet is strongest in the second."
The girls stood straining their eyes to see things they had not thought of before. Miss Miller waited a moment to give them time to verify her statements, then she said, "Every rainbow has seven arcs presenting the seven colours of the solar spectrum. Sometimes the moon will produce rainbows but they are of very pale colouring. I could tell you all about the degrees and rays that go to elucidate facts about a rainbow, but you would only be in a maze when I was through, so I will tell you the simple fact of causation, then some other time we might go into the subject from a scientific basis.
"A rainbow is produced by the decomposition of the white light of the sun when it passes into the rain-drops, then reflecting from their inside face; or when solar light passes into drops of water under a certain angle.