"Well, Daddy," asked Mab, after Mr. Blake had sat silent for some time, "have you thought of a way to tell us what makes the shiny stuff in the—in the—in the—Oh! I can't say that big word!" she finished with a sigh.

"The mercury in the thermometer!" laughed Daddy Blake. "You want to know what makes it go down? Well, it's the cold. You see cold makes anything get smaller and shrink, and heat makes things swell up, and get larger. That's why the steam from hot water swells up and makes the engine go, and pull the cars.

"And in hot weather the mercury swells, puffs itself out and creeps up inside the little glass tube. In winter the mercury gets cold, and shrinks down, just as it is doing to-night."

"But will it get cold enough so you can tell us the secret?" Hal wanted to know, mos. . . Read More