Page:The Winning Touchdown.djvu/225

Rh has to do with heat and cold, sudden changes of temperature and the effects produced by each. Very interesting, very. I trust you are all prepared?"

"If we aren't, it's funny," murmured Dutch, for they had recited on it several times in review.

"Speaking of the changes produced by sudden changes of temperature, can you give me a common example?" asked the president, his eyes roving about the room. Dutch seemed so eager to recite, and have it done with, that his agitation could not but be noticed. "You many answer, Mr. Housenslager," finished Dr. Churchill.

"Ice and snow," came the ready reply. Dutch breathed easy again. He thought he was done for the day.

"Very true," continued Dr. Churchill easily, "but that is a little too common. I referred to the Prince Rupert drops. I dare say you all know what they are. Mr. Housenlager, you will kindly explain to the class how they are made, the effect they produce, and what principle they illustrate."

The doctor sat down, and all eyes were once more turned toward Dutch. Nearly every lad in the class could have given some sort of answer, for they had seen the curious glass drops broken by their regular teacher. But, as it happened, Dutch had been absent when that subject came up, and, as he made it a practice never to inquire what