Page:America's National Game (1911).djvu/519

 alter its own course, how can such a result occur? To cause the ball to curve would require the constant, attendant action of some controlling power along its entire pathway; but as no such accompanying agency exists there cannot possibly be such a thing as a curve to the right or left of the true line.'

"Professor Lewis Swift, of the Rochester University, thus set forth his ideas of the curved ball problem, correcting at the same time the erroneous report that he had predicted the feat as impossible.

"'In complying with the request to give a philosophical reason for the curvature of a ball by Base Ball experts, I do so the more cheerfully to correct an impression that I am a disbeliever in the performance of such a feat, which statement, unauthorized by me, was first promulgated in your paper. It is true that some time ago, when the subject was first broached to me, I denied that it was possible to do it, but when so many keen-eyed observers asserted that they had seen it repeatedly done, I began to investigate the matter, and soon saw, that instead of being impossible, it was in accordance with the plainest principles of philosophy. I will now as plainly and briefly as I can, consistent with clearness, proceed to give an explanation of what, at first thought, and without having seen it, one would suppose to be contrary to the laws of motion. In the first place, let it be borne in mind that when a ball is thrown with great velocity, and especially against the wind, the air in front is considerably condensed, but if the ball has no rotation, the only effect of the air's resistance is to impede the velocity, but not so when the ball rotates. 1. Suppose a ball to be fired from a rifled cannon—say to the east—the ball emerges with a rapid rotation at right angles to the direction of motion. One face of the ball is continuously in front, the upper, the lower, the north and the south sides of that face, pressing constantly and equally against the air, consequently it has by its rotation no tendency to deviate in any direction. It may be well here to state that the object in giving such a ball a rotation is (as no ball can be made equally dense in every part and perfectly round) to present every part of the forward face on every side of the line of motion, all inequalities, therefore, of density and symmetry are at every instant equally divided on all sides, and the ball will go undeviatingly in the direction desired.

"'2. Suppose a pitcher should throw a ball, say to the east, giving it a rotation whose axis should correspond with the northern and southern horizons. The air in front being more dense than in the rear, of course the friction of the rotating ball will be greatest on the front side, and will cause it to deviate, not to the right nor left, but slightly up or down, depending in which way the ball rotates.

"'3. Suppose the pitcher, at the instant the ball leaves his hand,