“According to that, Joe could throw a ball after the Empire State Express when it was running at that speed and hit the rear platform,” was the incredulous comment of Ben Atkins. “I knew that ball was going mighty fast but I didn’t think it was as swift as that.” “It’s a pity that there isn’t some certain way of finding out,” commented Tom. “It has been found out,” said Joe calmly. “Is that so?” “How was it done?” “Why,” replied Joe, in answer to the volley of questions fired at him, “it wasn’t a hard thing at all. You know the big arms factories have a contrivance that tells them just how fast a bullet goes after it leaves the gun. They have two hoops set in a line say two hundred feet apart. These hoops are covered with a mesh of fine wires that are connected by electricity with a signal room. The bullet as it goes through the first hoop cuts a wire which registers the exact fraction of a second at which it is hit. The bullet strikes another wire as it goes through the second hoop and this also registers. Then all they have to do is to subtract the first time from the second and they have the exact time it has taken for the bullet to go that two hundred feet.” “Seems simple enough when you come to think of it,” remarked Tom. “Then,” went on Joe, “it struck somebody that it would be perfectly easy to rig up a couple of hoops sixty feet apart and let a pitcher hurl a straight ball through both and then measure the different times at which it struck the two hoops. They did it down at some Connecticut plant and got two of the swiftest pitchers in the big leagues to try out their speed. One of them put it through at the rate of one hundred and twelve feet a second and the other at the rate of one hundred and twenty-two feet a second. That’s why I said that that last ball of mine was going at over a hundred feet a second.” “Guess you knew what you were talking about, old boy,” said Tom, as he walked back to take his place again at the receiving end. “But after this, cut down the speed to eighty or thereabouts. That’ll be rich enough for my blood at present.” “All right,” grinned Joe. “We’ll cut out the fast straight ones and work out a few of the curves.” “Just what do you mean by curves?” asked a rather gruff voice. Joe turned and recognized Professor Enoch Crabbe of the Riverside Academy, who had been strolling by, and having caught a glimpse of the unusual number present through the open door, had concluded to add himself to the spectators. He was a man generally respected in the town, but very positive and set in his views and not at all diffident about expressing them. “Good afternoon, Professor,” said Joe. “I didn’t quite understand what you meant by your question. I was just going to curve the ball----” “That’s just it,” interrupted the professor with a superior smile. “You thought you were going to curve the direction of the ball, but you were going to do nothing of the kind. It can’t be done.”