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A baseball is a ball used in the sport of the same name, baseball. The ball features a rubber or cork center, wrapped in yarn, and covered, in the words of the Official Baseball Rules "with two strips of white horsehide or cowhide, tightly stitched together." It is in circumference, ( in diameter), and masses from .〔(【引用サイトリンク】 access-date = 2014-12-29 )〕 The yarn or string used to wrap the baseball can be up to one mile (1.6 km) in length. Some are wrapped in a plastic-like covering. A significant characteristic of the baseball is the stitching that holds together the covering of the ball. After a ball has been pitched, these raised stitches act like wings on a plane, catching the wind and causing the ball to swerve slightly on its way to the catcher. Whether the ball swerves to the right, to the left, downward, or a combination thereof, and whether it swerves sharply or gradually, depends on which direction, and how fast, the stitches have been made to spin by the pitcher. See, for example, curveball, slider, two-seamed fastball, four-seam fastball, sinker, cutter.〔Baseball Explained, by Phillip Mahony. McFarland Books, 2014. See (www.baseballexplained.com )〕 ==History== In the early, mid-1800s days of baseball, there was a great variety in the size, shape, weight, and manufacturing of baseballs. Early baseballs were made from a rubber core from old, melted shoes, wrapped in yarn and leather. Fish eyes were also used as cores in some places. Pitchers usually made their own balls, which were used throughout the game, softening and coming unraveled as the game went on. One of the more popular earlier ball designs was the "lemon peel ball," named after its distinct four lines of stitching design. Lemon peel balls were darker, smaller, and weighed less than other baseballs, prompting them to travel further and bounce higher, causing very high-scoring games. In the mid-1850s, teams in New York met in attempt to standardize the baseball. They decided to regulate baseballs to weighing between 5.5-6 oz and having a circumference of 8-11 inches. There were still many variations of baseballs since they were completely handmade. Balls with more rubber and a tighter winding went further and faster (known as "live balls"), and balls with less rubber and a looser winding (known as "dead balls") did not travel as far or fast. This is generally true for all baseballs. Teams often used this knowledge to their advantage, as players from the team usually manufactured their own baseballs to use in games. There is no agreement on who invented the commonplace figure-8 stitching on baseballs. Some historians say that it was invented by Ellis Drake, a shoemaker's son, to make the cover stronger and more durable. Others say it was invented by Colonel William A. Cutler and sold to William Harwood in 1858. Harwood built a factory in Natick, Massachusetts, and was the first to popularize and mass-produce baseballs with the figure-8 design. In 1876, the National League was created, and standard rules and regulations were put in place. A.G. Spalding, a well-known baseball pitcher who made his own balls, convinced the NL to adopt his ball as the official baseball for the NL. It remained that way for 100 years. In 1910, the cork-core ball was introduced. They outlasted rubber core baseballs; and for the first few years they were used, balls were hit farther and faster than rubber core balls. It eventually went back to normal. In 1920, a couple of important changes were made to baseballs. They began to be made using machine winders and a higher grade of yarn from Australia. Although there was no evidence that these balls impacted the game, offensive statistics rose throughout the 1920s, and both players and fans believed that the new balls helped batters hit the ball farther.〔(【引用サイトリンク】url=http://www.baseball-reference.com/bullpen/Baseball_(equipment) )〕 In 1925, Milton Reach patented his "cushion cork" center. It was a cork core surrounded by black rubber, then another layer of red rubber. In 1934, The National League and American League came to a compromise and standardized the baseball. They agreed on a cushion cork center; two wrappings of yarn; a special rubber cement coating; two more wrappings of yarn; and, finally, a horsehide cover. Baseballs have gone through only a few small changes since the compromise. During World War II, the US banned the use of rubber for non war-related goods, including for baseballs. So in 1943, instead of using rubber, baseballs were made with rubberlike shells of ''balata''; a substance, obtained from a particular type of tropical tree, that was also used in golf balls. Hitting declined a lot in 1943. The introduction of synthetic rubber in 1944 resulted in baseballs returning to normal. In 1974, baseballs covers were switched from horsehide to cowhide. In 1976, MLB stopped using Spalding for manufacturing their baseballs and started using Rawlings. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Baseball (ball)」の詳細全文を読む スポンサード リンク
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