"Oh, bother!" Burt answered, flushing slightly, "I've forgotten. Some
principle of latent heat involved, I believe. Ask Webb. If he could live
long enough he'd coax from Nature all her secrets. He's the worst Paul
Pry into her affairs that I ever knew. So beware, Amy, unless you are
more secretive than Nature, which I cannot believe, since you seem so
natural."

"I'm afraid your knowledge, Burt, resembles latent heat," laughed
Leonard. "Come, see what you can do, Webb."

"Burt is right," said Webb, good-naturedly; "the principle of latent heat
explains it all, and he could refresh his memory in a few moments. The
water does not draw the frost from the plants, but before it can freeze
it must give out one hundred and forty degrees of latent heat. The
flower-room and root-cellar were therefore so much warmer during the
night than if the water had not been there. The plants that were nipped
probably suffered after the ice became so thick as to check in a great
measure the freezing process."

"How can ice stop water from freezing?" Alf asked, in much astonishment.

"By keeping it warm, on the same principle that your bed-clothes kept you
warm last night. Heat passes very slowly through ice-that is, it is a
poor conductor. With the snow it is the winter wrap of nature, which
protects all life beneath it. When our ponds and rivers are once frozen
over, the latent heat in the water beneath can escape through the ice but
very gradually, and every particle of ice that forms gives out into the
water next to it one hundred and forty degrees of heat. Were it not for
these facts our ponds would soon become solid. But to return to the tub
of water in the flower-room. The water, when placed there, was probably