Wiffle ball is a variant of baseball played with a plastic perforated ball. Eight three-quarter-inch, oblong holes cover half the ball’s surface area, while the other hemisphere is uninterrupted. Originally designed to relieve the arm of a young baseball pitcher (the son of its inventor, David N. Mullany), the ball achieves a curving trajectory without requiring the pitcher to impart spin or hurl at top speed. Each ball is packaged with instructions for how to release it in order to achieve various effects—with the perforations up for a straight ball, toward the pitcher’s thumb for a curve, and toward the outer fingers for a slider.
The inventor’s grandsons still run the family enterprise, with a product unchanged since its 1953 launch. Their dad, the pitcher for whom the ball was designed, told The Atlantic in 2002 that the Mullany family believed cutting the holes might create a “weight imbalance” that would cause the ball to curve. To this day, the company insists, “we don’t know exactly why it works—it just does!”
That folksy answer is charming, but a scientific one can foster even greater admiration for this curious ball and the sport that makes use of it.
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Before Wiffle ball, uncertainty over the baseball curveball motivated investigation from both the media and the scientific community. Life magazine commissioned photographic studies of curve balls in 1941, to determine whether the phenomenon was real or an optical illusion. The magazine’s editors concluded it was illusory, enraging pitchers of the era.