essional Library, only second to it in beauty, and the Washington
Monument soaring into the air to a height of five hundred and fifty-five
feet, and the superb Lincoln Memorial, and a host of other things
scarcely less wonderful.

"But the pleasantest recollection I have of the trip," he went on, "was
the speech I heard the President make just before I came away. It was
simply magnificent."

"It sure was," replied Bob enthusiastically. "Every word of it was worth
remembering. He certainly knows how to put things."

"I suppose you read it in the newspaper the next day," said Mr. Preston,
glancing at him.

"Better than that," responded Bob, with a smile. "We all heard it over
the radio while he was making it."

"Indeed!" replied the principal. "Then you boys heard it even before I
did."

"What do you mean?" asked Joe, in some bewilderment. "I understood that
you were in the crowd that listened to him."

"So I was," Mr. Preston answered, in evident enjoyment of their
mystification. "I sat right before him while he was speaking, not more
than a hundred feet away, saw the motion of his lips as the words fell
from them and noted the changing expression of his features. And yet I
say again that you boys heard him before I did."

"I don't quite see," said Herb, in great perplexity. "You were only a
hundred feet away and we were hundreds of miles away."

"And if you had been thousands of miles away, what I said would still be
true," affirmed Mr. Preston. "No doubt there were farmers out on the
Western plains who heard him before I did.

"You see it's like this," the schoolmaster went on to explain. "Sound
travels through the air to a distance of a little over a hundred feet in
the tenth part of a second. But in that same tenth of a second that it
took the President's voice to reach me in the open air radio could have
carried it eighteen thousand six hundred miles."

"Whew!" exclaimed Jimmy. "Eighteen thousand six hundred miles! Not feet,
fellows, but miles!"

"That's right," said Bob thoughtfully. "Though I never thought of it in
just that way before. But it's a fact that radio travels at the rate of
one hundred and eighty-six thousand miles a second."

"Equal to about seven and a half times around the earth," observed the
principal, smiling. "In other words, the people who were actually
sitting in the presence of the President were the very last to hear what
he said.

"Put it in still another way. Suppose the