Ball

• 1. Introduction

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  A ball is a round object, usually spherical but sometimes ovoid, and for most of human history the ones people played with had never touched rubber. When the Spanish reached the Americas after the voyages of Columbus, they became the first Europeans to see bouncing rubber balls, employed most notably in the Mesoamerican ballgame. Those balls were solid, not inflated, and the material itself was unknown outside the Americas until that encounter. Everywhere else, balls used in sport before Columbus were made from animal bladders or skins, stuffed with whatever was on hand. The word ball itself first appears in English in 1205, in a chronicle describing men driving balls across open fields. From Egyptian monuments to Roman bathhouses to a modern basketball inflated to a precise pressure, the ball has carried very different materials and rules while staying, at its core, the same simple round thing.

• 2. What The Word Once Meant

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  In 1205, the chronicler behind Layamon's Brut wrote the line "Summe heo driuen balles wide ȝeond þa feldes," or "Some of them drove balls far across the fields," the first known use of ball in English to mean a globular body played with. The word came from Middle English bal, itself from Old Norse böllr, tracing further back to a hypothesised Proto-Germanic root, ballu-z. No Old English cognate of any of these forms is known to exist. In later Middle English spelling, the word balle came to look identical to the French balle, meaning both ball and bale, which led people to wrongly assume the French word was the source. French balle is itself now thought to be of Germanic origin. If the Germanic root ball- was original rather than borrowed, it may be a cognate of the Latin foll-is, meaning a thing blown up or inflated, the same root that later gave the Romans a name for their own air-filled ball. In Ancient Greek, two separate words for ball are attested, palla and sphaira, the second of which survives today as sphere.

• 3. Play In The Ancient World

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  Some form of ball game appears portrayed on Egyptian monuments, among the earliest evidence of the object being used for sport rather than work. In Homer, Nausicaa was playing at ball with her maidens when Odysseus first saw her in the land of the Phaeacians, and elsewhere Halios and Laodamas performed ball play accompanied by dancing before Alcinous and Odysseus. The oldest balls yet discovered in Eurasia were found at Karasahr in China, made of hair-filled leather and dated to roughly 3000 years old. Among the ancient Greeks, ball games were treated as a gentler alternative to more violent athletic exercise, valued for keeping the body supple and graceful, and largely left to boys and girls rather than serious athletes. Few formal rules survive. Julius Pollux catalogued several named games: aporraxis, bouncing a ball off the ground with an open hand; ourania, flinging a ball into the air to be caught by two or more players; and phaininda, a catching game in which feinting tested a player's quickness. Pollux also describes episkyros, played by two lined-up sides, often regarded as an ancestor of football, though how it used anything like a goal remains uncertain. Because a perfectly spherical ball was hard to produce, children often made their own by inflating pig's bladders and heating them in ashes to round them out, while Plato, writing in the fourth century BC, described balls covered in twelve leather pieces. The Romans treated ball games as an accompaniment to bathing, graduated to a bather's age and health, with a dedicated space called a sphaeristerium set aside within the baths. They recognised three sizes: the small pila used in catching games, the paganica stuffed with feathers, and the largest, the air-filled follis, struck from player to player by men wearing a kind of gauntlet. Trigon was played by three people standing in a triangle using the follis, while harpastum involved several players scrambling for the ball at once. Though these games reached the Romans, their names remained Greek.

• 4. The Physics Of Play

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  Many modern balls are pressurised, some at the factory, such as tennis and squash balls, and others by the people using them, such as volleyball, basketball and football. Nearly all pressurised balls leak air gradually, and where a ball is factory pressurised there is usually a rule governing how much pressure it must retain to stay playable. A depressurised ball loses its bounce and is often called dead, and in extreme cases it can go fully flaccid. Because ball pressure follows the ideal gas law, it changes with temperature and generally tracks the surrounding conditions; softer balls struck hard, squash balls especially, heat up through inelastic collision. In outdoor sports, a wet ball plays differently from a dry one, and indoors, hand sweat alone can leave a ball damp enough to change its behaviour. Not every ball relies on internal pressure at all. Some sports, including most hockey variants and lacrosse, use a solid ball with uniform material, while others, such as baseball and cricket, use different layered materials, and a few, including sepaktakraw, pickleball and floorball, use a hollow ball instead. Moisture changes how a ball behaves in play, since wet or damp surfaces alter the friction a player can use to impart spin, a motion governed by the physics of angular momentum. A spinning ball moving through air, which is technically a fluid, experiences the Magnus effect, producing sideways deflection on top of the ordinary curve caused by wind resistance and gravity.

• 5. One Shape, Many Rules

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  A regulation baseball, made with a cork or rubber core wrapped in yarn and covered in horsehide or cowhide, measures 20.84 centimetres in circumference and weighs 84.8 grams, and must withstand 7.99 kilogram-force of pressure without excessive deformation. A basketball, by contrast, is inflatable and measures 75 to 77 centimetres around, weighing 580 to 620 grams, built to bounce between 1.035 and 1.085 metres when dropped from a height of 1.8 metres. Golf uses a solid ball just 1.68 inches across and 1.62 ounces in weight, made from elastomeric material, while table tennis uses an air-filled plastic ball only 4 centimetres wide and weighing 2.7 grams. A rugby union ball is a prolate spheroid rather than a true sphere, measuring 74 to 77 centimetres around its longer circumference and 58 to 62 centimetres around the shorter one, made of leather or a synthetic equivalent. A volleyball measures 65 to 67 centimetres around and weighs 260 to 280 grams, while a sepaktakraw ball, hollow and woven from synthetic fibre, measures just 41 to 43 centimetres around and weighs 170 to 180 grams. A field hockey ball is solid, 22.4 to 23.5 centimetres around and 156 to 163 grams, and a tennis ball is regulated to hold a pressure of 1 psi. Beyond sport, balls made from hard-wearing materials serve engineering uses too, forming the very low friction bearings known as ball bearings, and long before that, black-powder weapons fired stone and metal balls as projectiles. Because a ball is one of the most familiar spherical shapes people encounter, the word has also come to describe spherical or near-spherical things generally, as when an armadillo or a person curls up into a ball, or a hand closes into a fist. From a pig's bladder inflated and heated over ashes by ancient Greek children to a basketball engineered to bounce within a few centimetres of a fixed standard, the round object has kept expanding into new specifications without ever losing its original, simple shape.