"When we are placed at a certain angle on the earth, we look up at the spot where the rainbow is said to be, and the sun shining opposite it produces on the retina the sensation of colours. You never see a rainbow at high noon, yet the rays of the sun are intense enough. But there is no reflection at noon, upon clouds that you can see. There may be a rainbow at that time somewhere in the clouds, but you can't see it.
"The geysers in the National Park out West produce the same phenomenon, but in not such brilliant colourings. Sometimes, a double rainbow appears over Niagara Falls, and on almost any clear day you can see one large rainbow."
The girls listened to the interesting explanation while following the Guide down through the ravine. As they neared the Bluff, the sun began shining again in unclouded brightness, and only the drops of water on leaves and rocks told one of the shower.
Arrived at camp, everything was found to be in good condition, the tents having shed water beautifully; the Guide's selection of site proved wise inasmuch as the rain drained away from all sides of the spot where the tents stood.
Zan ran to her tent to see if Nita was sleeping. But no one was there. She came out again and looked at Miss Miller in astonishment. The Guide expected to hear that Nita had gone to bed to hide her ears from the thunder, and was surprised when Zan told her that Nita was not to be seen.
"She took refuge with Sherwoods' when the first peal of thunder sounded," said Miss Miller.
"I'll run down and let her know we are back. If she wishes to join us, all right, but I won't coax her to," whispered Zan, and the Guide nodded her approval.
But Zan came back alone after a long interval. She expressed concern in her face when Miss Miller asked about Nita.
"Mrs. Sherwood said she saw one of the girls coming down her foot-path with my mother's purple sun-shade. She was surprised and watched her go along the road that leads to the Big Bridge."
"There, now! That is where I saw that purple parasol! I sat on top of Baldy while waiting for you girls and as I looked at the valley view I spied a tiny form walking along the road with a dash of purple over her head. I sat wondering where I had seen a purple sun-shade—it seemed quite recently. But now I remember you carried one from the house when you brought some of the luxuries," said Miss Miller.