The Shark, in no wise disturbed by the raillery, produced and unfolded a big sheet of paper, bearing a curious diagram and what appeared to be an elaborate calculation.
“The problem may be stated thus,” he began. “Given a weight of fifteen pounds, seven and nine-tenths ounces, what is the force required to propel it for a distance of thirty-five feet?”
“Thirty-five feet? How do you get that?” queried Step.
“The table stood eighteen feet from the window,” the Shark explained. “The table-top, which the stone struck, was two and a half feet from the floor. I estimate that the stone, if it had not struck the table, would have traveled at least five feet farther. Then it was thrown from a point at least twelve feet from the building—if you take the trouble to inspect the ground you will see that the thrower must have been so far from the wall to have secure footing. Now then, eighteen and five and twelve make thirty-five.”
“Go on!” urged Step.
“We have the weight of the object moved, and the distance moved. To aid us in plotting the curve of flight of the object, we have three known points, or, rather, two known points and one which can be closely approximated. We know the height from the floor at which the stone broke the window-pane—seven feet, nine inches. The table-top, as I have said, was thirty inches from the floor. The approximated point is the distance from the ground (or, rather, from the level of the floor projected for the calculation twelve feet beyond the window), at which the stone began its journey. This distance was not less than five feet nor more than six, allowing for a rise in the ground, and assuming that propulsion began about on a level with the thrower’s shoulder. But whether it was five or six——”
“Hold on! Hold on!” cried Step. “You’ve got me going!”
“Huh! Can’t be made clearer, can it?” expostulated the Shark. “But if you’ll look at the diagram——”
Step threw up his hands in burlesqued horror. “No, no! Take it away! I can’t bear the sight of the thing out of school hours!”
“Never mind about the pretty picture, Shark!” chimed in the Trojan.