"Not even to mamma?" asked Ruthy, who always felt better when she told her mother all about everything.
"No, not to anyone in all the wide world," Ruthy answered. "I won't tell you a single word unless you promise, and you will be awfully sorry if I don't tell you, for this is the most splendid plan I ever made up in all my life. It is just like a book."
Ruthy's curiosity overcame her scruples about knowing something which she could not tell her mother.
"All right, I won't tell a single person," she said, earnestly. "Tell me what it is."
"Promise across your heart," Ruby insisted, for just then the little girls had a fashion of thinking that promising across their hearts made a promise more binding than any other form of words.
"I promise, honest true, black and blue, 'crost my heart," Ruthy said very earnestly, and then the two heads were put close together while Ruby whispered her wonderful secret.
No one could have heard them, not even the birds in their nests up in the tree, if she had spoken aloud, but a secret always seemed so delightfully mysterious when it was whispered, that she rarely told one aloud.
"I am going to be cast away on a desert island," she said, and Ruthy's blue eyes opened to their widest extent.
"Why, how can you, when there is n't any desert island anywhere near here for miles and miles?" she exclaimed.
"Oh, you are so stupid," Ruby exclaimed impatiently. "Of course I mean to pretend I am cast away. I am going to pretend that down by the barn is a desert island, and that little house I have built with boards is my hut, and I am going to sleep out there all by myself to-night, and I have some provisions and everything all ready."