This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
Baseball season is officially underway! And what better way to celebrate than by looking at the ball that drives the game?
On supporting science journalism
If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
A few years ago, I talked S into helping me take apart a baseball. I wanted to understand the properties that Johan Santana can hold in his hand and with the flick of his wrist, turn into a lethal strike. Armed with my old lab kit, we proceeded with an unorthodox dissection.
First, the 108 stitches that comprise the seam had to be removed. The seam is hand sewn on every baseball (and MLB teams use approximately 600,000 balls a season combined, which means a lot of labor). Once the red waxed thread was gone, we peeled back the cowhide to reveal a layer of yarn. Cowhide was introduced in 1974 due to a shortage in horsehide. The leather is tested for 17 potential deficiencies in thickness, grain strength, tensile strength and other areas before being sewn onto the ball.
The first layer of the naked baseball (working from the outside-in to the core) is a layer of white poly/cotton finishing woolen yarn. There are four layers of wool and cotton windings that cover the core. After the first layer, the subsequent layers are varying gray and white woolen yarn of assorted grades. Why wool? Wool is naturally resilient and when compressed the material can rapidly return back to the original shape. This property helps baseballs retain their shape even after being hit repeatedly during a game. Though the photos below don't show the ball's diminishing size with each layer removed, it was interesting to see how much wool actually makes up a baseball.
The center of the ball is composed cork encased by a thin layer of red rubber. The rubber was easy enough to understand: it essentially made the ball, well, a ball. Cutting into the rubber revealed the cork center, known as the pill. Apparently, cork was selected as the core material in 1910 as one means of standardizing baseballs. Prior, the core was rubber. The change allowed for "livelier" baseballs, which I assume means that the cork center allowed for greater flexibility in delivery—it let the ball behave differently depending on how the pitcher released it. According to the University of Illinois, the cork center had a tremendous effect on the game:
With the introduction of the cork center baseball in 1926, pitchers soon began to develop freak deliveries- shine ball, spit ball, emery ball, etc. Drastic changes were made in the rules in 1920 to outlaw these pitches. However, recognized "spit ball" pitchers were permitted to continue using their specialty for the remainder of their careers. Most successful of these, and the last to close his Major League career, was Burleigh Grimes, who pitched last for the Yankees in 1934.
To deal with these issues, the core was changed again: it was encased in rubber to become the modern pill below:
As I considered this small piece of cork, it occurred to me that in this seemingly simple baseball was a global history—which is interesting considering that baseball is labeled as an All-American sport. Cork has been in use since at least 3000 BC in fishing tackle in China, Egypt, Babylon, and Persia. And evidence of cork being used for floats, stoppers, women's footwear, and roofing materials have been found in Italy dating the the 4th-century BC. Both cork and rubber come from trees, forests and plantations in Portugal, Spain and Italy for cork, and in Brazil, Ceylon, Borneo, the Malay Peninsula, India, and England. The processes for use and refinement have been cultivated and handed down through the ages—including the idea for a cork center for a ball, which dates back to 1863 when an Englishman patented the cork center for cricket.
So, the next time you're at a baseball game, in between hotdogs and yelling at the umpire, consider what has gone into the tiny white sphere that's traveling at speeds of 98 mph.
See the full dissection on the AiP Facebook page.
A version of this post appeared on the original home of AiP on March 29, 2010.
