“It’s all right, Bert. The science class is studying motion, and I want to illustrate to them the principle of the gyroscope. I have that kind of a top here, but I had no common top, and I remembered seeing you spin yours, and that it was a large red one, which can easily be seen when you spin it on the platform in front of the high-school class. You see I want to show the science boys and girls the difference between a gyroscope top and the common top.”
“And you want me to spin a top in school—for a lesson?” asked Bert in surprise.
“That’s it—yes,” answered the principal. “I think you know what a gyroscope top is, don’t you?” Bert did, having been given one for Christmas. Mr. Tarton quickly brought his queer top out and spun it.
A gyroscope top is a heavy, small wheel fitted inside a round ring of metal, and the ring has a sort of top peg on it. When the heavy wheel inside the metal ring is set spinning by means of a string wound about it and pulled off, the wheel goes so fast that it will hold up the metal ring in any position. Thus the gyroscope top will spin upside down, lying on its side and in many other positions.
“But your top will spin in one way only, and that is standing straight up, Bert,” said the principal. “That’s what I want the boys and girls in the high-school class to understand. Of course I could tell them about it, but they will learn much more quickly if they see the two different tops spinning in front of them. So come with me now, if you please, and bring your top.”
Bert could hardly help smiling as he followed the principal to the high-school part of the building. It seemed so queer to be asked, as a favor, to spin a top in class. But the older boys and girls were as much in earnest as was Mr. Tarton. They wanted to learn this rule about spinning bodies, for the earth we live on, you know, spins about like a giant top. So the high-school lads and lassies did not laugh when Mr. Tarton wound up and spun the gyroscope nor when Bert set his red top to spinning. They asked many questions and seemed eager to learn. Bert himself was much interested.
“You are a good top-spinner,” said Mr. Tarton to him when the lesson was over. “You may go back to your class, and you may take the gyroscope top with you and tell Miss Skell I said you could spin it and show the smaller boys and girls how it works.”
So the mystery of why Bert was sent to the principal’s office was soon solved. Going back to his room, in a few words Bert told Miss Skell about it. He also delivered the message about the gyroscope, and soon the boys and girls were much interested in watching Bert spin it on Miss Skell’s desk.
“If she’d let us write a composition about that funny top I believe I could do a good one,” said Nellie Parks to Nan when the class was let out for the noon recess.
“But the prize composition must be about something that happens on our summer vacation,” answered Nan. “Oh, I do hope I win the prize!”